25 August 2016, Volume 38 Issue 4
    

  • Select all
    |
  • Preliminary study of coupled DEM-analytical method in analyses of deeply buried tunnel excavation
    WANG Huaning, XIAO Guo, JIANG Mingjing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 867-874. https://doi.org/10.7522/j.issn.1000-0240.2016.0097
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Distinct element method (DEM) is suitable in simulations of laboratory test and local small-scale problem. As for large scale problems including tunnel excavation, DEM simulation could be complex and time consuming. In order to expand the applicability of DEM in large scale analyses, acoupled DEM-analytical solution methodis proposed. So as to study the feasibility and error of the coupled method, the excavation of a deeply buried circular tunnel is analyzed during the elastic stage. The surrounding rock which nears the tunnel is analyzed by DEM, and the displacement and stresses of far field area are obtained by analytical solutions. Iteration procedure is used to ensure the continuity of stress and displacement along coupled boundary. Tunnels with and without inner-pressure are both analyzed as two cases. Generally, after 15 iterations, the difference between the resulting boundary displacement and the theoretical solution were 1.86% and 3.2% for two cases, respectively.Results of the DEM model comparing with the theoretical solution arefine: the errors of the displacement are related with the angle and the largest one is less than 13.5%; the errors of stress in some points are about 15% and the rest are within around 8.6%. It is shown that the coupled method has considerable accuracy and feasibility in mechanical analysis of tunneling.
  • A disturbed state constitution model of rock under high temperature
    WU Gang, SUN Hong, ZHAI Songtao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 875-879. https://doi.org/10.7522/j.issn.1000-0240.2016.0098
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    It is necessary to carry out the constitutive relation of rock under high temperature because a lot of rock engineering involves the problem of high temperature rock. In this paper, based on the theory of disturbed state concept, a disturbed state constitutive model of high temperature rock is established by defining the temperature dependent disturbance function. The constitutive model is verified by the uniaxial compressive failure test of granite under high temperature. The study shows that the established constitutive model can describe the mechanical response characteristics of high temperature rock.
  • Quantitative analysis on double reduction method
    ZHU Yanpeng, YANG Xiaoyu, YE Shuaihua, MA Xiaorui, LI Jingbang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 880-888. https://doi.org/10.7522/j.issn.1000-0240.2016.0099
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Double reduction method (DRM) adopts reduction strategy which utilizes the different reduction coefficients of strength on the cohesion and internal friction angle and this view is more rational. However, the research on double reduction method still lacks of quantitative analysis or reasonable explanation. In the coordinate system of strength parameters, definition of FOS, path of reduction, and critical state are used to analyze the difference between traditional strength reduction method (SRM) and DRM. There is unity in path of reduction with these two methods; DRM can be regarded as the SRM where it begins at an initial virtual strength point to reduce. The gradual process of slope destruction is the attenuation of strength parameters. In this process, c and tan φ follow direct proportion function. At the same time, in the coordinate system of strength parameters, the concept of strength reserve can be reflected as the gradual process which is initial strength area approaches to critical strength area. Using these concepts can get the expression of the final FOS. Research of strength reduction method should concentrate on strength, and the reduction of strength parameters are just a way to achieve purpose of strength attenuation. Definition of FOS and regression analysis all indicate that critical state is inherent property of slope, given geometric model of slope, the critical state is constant, which is not related to initial strength parameters. The different critical points lead to the different results between DRM and SRM.
  • Theoretical and experimental study of relation between in-situ stress and rock mass modulus
    PEI Qitao, DING Xiuli, HUANG Shuling, LUO Chaowen
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 889-897. https://doi.org/10.7522/j.issn.1000-0240.2016.0100
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Rock mass modulus (elastic modulus and deformation modulus) is one of the basic parameters in rock engineering. It is of great significance to find out the relationship between in-situ stress and rock mass modulus. Combing with the elasto-static thermal stress model as well as the theory of elasticity, the relation of horizontal principal stresses and rock mass property parameters is quantitatively established. Then, the effect of rock mass modulus on the distribution of in-situ stress is discussed. On the basis, an in-situ stress measurement and rock mass modulus test are carried out in Meihuashan tunnel, and the comparison between the measured results and the theoretical results are made. The results are as follows: When the influence of buried depth is less, the relation between horizontal principal stresses and rock mass modulus shows a positive linear correlation in granite. However, when the buried depth varies large and its effect on in-situ stress and rock mass modulus can't be neglected, the relation between horizontal principal stresses and rock mass modulus turns out to be a positive nonlinear correlation. In granite, the relative coefficient between horizontal principal stresses and rock mass deformation modulus exceeds the relative coefficient between horizontal principal stresses and rock mass elastic modulus. Therefore, the results above can provide great reference to determine rock mass mechanical parameters in rock engineering.
  • Parameter inversion analysis of saturated porous media in frequency domain
    MA Qiang, ZHOU Fengxi, LIU Yunshuai
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 898-903. https://doi.org/10.7522/j.issn.1000-0240.2016.0101
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the Biot theory, the governing equations in terms of displacement of solid skeleton are derived, where the solid particles and fluid are assumed to be incompressible. The analytical expressions of the skeleton displacement, the soil pressure and pore fluid pressure are obtained by theoretical derivation, in which for one-dimensional transient response of single-layer fluid-saturated porous media loaded harmonic at its top surface is take into account. According to the principle that the test data of harmonic dynamic model of saturated soil and theoretical solutions should be fitted, the parameter inversion problem of porous media is reduced to optimal problem of non-linear multimode function. The genetic algorithm and simulate annealing are sued to search for the global optimal solution, and by experiments and numerical examples are demonstrate the correctness of the presented solution.
  • Discussion on the coefficient of consolidation of soft soil
    WANG Jili, CHEN Pan, LIU Jinlong, WEI Changfu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 904-908. https://doi.org/10.7522/j.issn.1000-0240.2016.0102
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In analysis of soil consolidation, it is necessary to correctly estimate soil super static pore water pressure dissipation and settlement process, important is to determine the value of reliable consolidation coefficient Cv. In this paper, along the Tianmen-Xiantao Highway soft soil subgrade engineering choice of two test sites to carry out in-situ tests and laboratory tests, and combined with the data of soft soil consolidation tests in the Pearl River estuary. The law of consolidation coefficient of soft soil is studied, and the method of determining the coefficient of consolidation is discussed. Research shows that: (1) consolidation coefficient Cv values obtained by the in situ pore water pressure dissipation tests are an order of magnitude larger than the corresponding values obtained by the indoor high pressure consolidation test time square root method; (2) consolidation coefficient Cv values obtained by the indoor high pressure consolidation test time square root method are greater than the corresponding values obtained by the time logarithm method, the inflection point method, three point method and Scott method; (3) due to the inflection point method, three point method and Scott method determine the consolidation coefficient Cv value has its respective advantages, in practical engineering are worth to try and promote.
  • Seepage analysis method research of steel cylinder structures
    CAO Hong, YANG Yun, PAN Hong, ZHOU Hongxing, LUO Guanyong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 909-914. https://doi.org/10.7522/j.issn.1000-0240.2016.0103
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The steel cylinder structure has been widely used in sea-crossing bridges and port project, but hardly any methods exist for evaluation of seepage analysis of the structure. The seepage of the steel cylinder structure relies on two parts, consisting of gap seepage and joints seepage. For the sake of analyzing increase in the head loss caused by the curve of local stream line in gap seepage of the steel cylinder structure, the calculation can be accessed under plane strain condition by introducing the concept of the extra seepage and theorizing the increase in the head loss to a low-permeability layer. In this assessment for analyzing joints seepage, the joints size was not found to be linked to the equivalent permeability coefficient, and joints gap can be seen as impervious while expanding the joints size of 400 times would just increase the equivalent permeability coefficient of 1.6 times comparing to the original data. It is apparent that the method worked well for seepage analysis of the Hong Kong-Zhuhai-Macau bridge project, because the result of the assessment method, which uses the two-dimension finite element program on horizontal plane for analyzing, has been successfully demonstrated by comparing to 3D numerical calculation.
  • A calculation method of retaining piles with circular beams for round deep foundation excavations
    ZHANG Jiaguo, XIAO Shiguo
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 915-921. https://doi.org/10.7522/j.issn.1000-0240.2016.0104
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In some areas of Southwest China consisting mainly of sandy cobble strata, circular deep foundation excavation engineering has gradually emerged in recent years. The support structures are almost retaining piles with circular beams connecting their tops and waists. But there has been no suitable calculation method for the structures. Based on structural mechanics analysis method, a calculation method of internal force and deformation for the structure is put forward in the paper. That is to say, according to the multi span continuous beam and elastic foundation beam model, internal force and deformation of a retaining pile segment above and below excavation face can be calculated respectively. Meanwhile, based on deformation compatibility relationship between the piles and beams, internal force and deformation of a beam can be analyzed further, and the theoretical calculation formulas are deduced. In order to verify the calculation method, a laboratory model test is conducted. The results show that, experimental distribution of lateral displacement of a pile is similar to theoretical one, which indicates the theoretical calculation method is reasonable. Finally, analysis results of a practical engineering are given in detail.
  • Stability analysis of borehole wall of digged foundation of transmission line during mechanized drilling
    CUI Qiang, HE Xiwei, CAO Danjing, SU Ding, XU Zhen
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 922-928. https://doi.org/10.7522/j.issn.1000-0240.2016.0105
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to investigate the stability of soils around the hole wall in digged foundation, this paper took the soils around the digged foundation by mechanized drilling as the research object, the finite-difference 3-D program FLAD3D was adapted to analyzing the distribution law of soil displacement, plastic zone and the stability of borehole wall during drilling. The calculation results show that the drilling rig weight and excavation unloading had the obvious effect on the soils horizontal displacement around orifice and enlarged base, and the soils plastic zone distribution after excavation also appeared the significant differences in two aspects: one was the plastic zone distribution area and the other was the plastic zone development range. Thus, soils deformation around orifice and enlarged base should be paid attention extensively in site construction process. This study provides theoretical basis for tower foundation designing and construction during transmission line mechanized construction.
  • The study on sensitivity of landslide induced by changes in loess structure
    CHEN Wenwu, LIU Wei, LIN Gaochao, WU Weijiang, SU Xing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 929-936. https://doi.org/10.7522/j.issn.1000-0240.2016.0106
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The loess landslide occurred frequently in the region of loess plateau in recent years. The extreme weather conditions and the heavy rainfall made the loess landslide become more than before in Tianshui, Gansu Province. A mass of loess landslide and loess-mudstone interface landslide triggered in Tianshui after a weekly continuous rainfall in August 2013. The resurrection of the loess landslide is often closely linked with the structure of loess. The undisturbed loess and remolded loess samples were chosen in the scarp of Huanancun landslide to operate consolidated undrained triaxial test by GDS triaxial apparatus. The results show obviously that the strain of undisturbed samples were strain softening, and the strain softening in remolded samples were weakened sharply. The result of strain softening was also undertaken by the stress path. The changes of pore water pressure in undisturbed and remolded samples were different from each other. At the beginning of shearing, the pore water pressure in the undisturbed samples increased slower than in the remolded samples.So the remolded loess was more sensitivity to the landslide than the undisturbed loess.
  • Design and development of a test system for measuring ultrasonic wave of frozen soil
    BING Hui, ZHAO Shuping, DU Yuxia, HUANG Xing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 937-942. https://doi.org/10.7522/j.issn.1000-0240.2016.0107
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The ultrasonic detecting technique is highly efficient, handy and non-destructive, and reflects the physical properties of the tested object, which is widely used in geotechnical engineering testing. A little work has been done particularly on the techniques and methods of obtaining the ultrasonic velocity of frozen soil, and the current testing work is unable to meet the testing accuracy. So based on the mainframe of ultrasonic detecting, its operating temperature is -5℃-+40℃, a test system for measuring ultrasonic wave velocity of frozen soil has been designed and developed sufficiently considering the frozen soil properties that it is sensitive to the temperature, the mass of energy transduce to the test object and the coupling between the testing object and the energy transduces. The system which can used to test the ultrasonic wave of the frozen soil with various sizes includes a constant temperature oven and the support for the energy transduces. The constant temperature oven offer the measurement environment with the temperature range from -30℃ to +30℃,and the support for the energy transduces can be put into the oven during testing. To avoid the influence of the energy transduce mass on the test in vertical measuring, the support offers the horizontal testing platform, and a strain gage have been placed to monitor the coupling extent between the energy transduces and the testing objects to improve the testing accuracy. The testing results of the frozen soil with various temperatures using the system indicate the feasibility of the test system.
  • Research progress on mechanical tests and properties of coarse-grained soil
    WANG Dingjian, TANG Huiming, ZHANG Yahui, LIN Chengyuan, ZHAO Meng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 943-954. https://doi.org/10.7522/j.issn.1000-0240.2016.0108
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Coarse-grained soil, as both geological mass and construction material, is extensively spread in nature. The mechanical properties of coarse-grained soil are of great importance to practical engineering in consequence. In review of related literatures, it was analyzed and summarized on tests and mechanical properties of coarse grained soils as follows: the tests fall into three types including laboratory, in-situ and numerical tests, respectively introduced about the testing principles, apparatus, operations, and applicability; especially, dilatancy, granular breakability and softening behaviors of coarse-grained soil are respectively summarized, from forming mechanism, influences and description methods perspectives. The overview above indicates four insufficiencies of research on coarse-grained soil mechanical properties: existing methods and theories have certain limitations; assumptions on genetic mechanisms of macro properties remain to be verified; it's difficult to deduce macro performances from mesomechanics perspective; multiphase coupling mechanical properties are seldom involved. Finally, the research prospects in mechanical properties of coarse-grained soil were put forward from the views of tests, theories and numerical simulations.
  • Experimental study on meso pore based on soil slice technique and its distribution describing
    TAO Gaoliang, BAI Liang, ZHUANG Xinshan, ZHANG Ran
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 955-962. https://doi.org/10.7522/j.issn.1000-0240.2016.0109
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The physical and mechanical properties of rock and soil porous materials are strongly influenced by their pore distribution characteristics, therefore study on meso pores has extremely important significance. The mixture of curing agent and blue organic dyestuff was used to solidify the eco-material samples, afterward,the typical sections of samples were obtained based on soil slicing technique. By using high resolution camera, the color digital images of sections were gathered, subsequently,the meso pore size distribution data was obtained with IPP technology. The results show that the porosity of aperture interval gives uniform distribution, the pore number distribution of different samples appears approximatively the same curve, which is smoother, the material structure is more stable. In order to describe reasonably the meso pore size distribution, an improved porosity model for describing pore size distribution was put forward, which has wider application range and smaller prediction error in the two-dimensional space compared with the existing porosity model.
  • Experimental research on unfrozen water content of sodium sulphate saline soil
    MA Min, BING Hui, LI Guoyu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 963-969. https://doi.org/10.7522/j.issn.1000-0240.2016.0110
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Unfrozen water content not only influences the physical and mechanical properties of frozen soil, but also is an important evaluation index of water migration. The moisture content of Lanzhou loess which contains different concentrations of sodium sulfate was measured by pulsed nuclear magnetic resonance (NMR). The influence of temperature and salinity on the unfrozen water content was analyzed. We simultaneously test the liquid and plastic limits of the samples containing different concentrations of sodium sulfate, and the freezing points of different water content of liquid and plastic limit. Based on the above data, the unfrozen water content was calculated according to wu=at-b so as to compare with the test value and the fitting parameters of the power function formula are also figured out. Then the temperature: -5℃, -10℃, -15℃ and -20℃ are chosen to analyze the relationship between unfrozen water content and salt content. The result shows that the change of unfrozen water content is not obvious in the mass, but the value becomes a maximum when the salt content is 2%. As a result, the fitting formulas based on different salinity ranges are established at the above temperature.
  • Numerical simulation of filter paper method for confirming equilibrium time
    LI Peng, TAN Xiaohui, XIN Zhiyu, WANG Xue, HU Muzi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 970-976. https://doi.org/10.7522/j.issn.1000-0240.2016.0111
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Filter paper method is an important method for measuring the matrix suction of unsaturated soil. It's very important to control the testing time which is one of the key points to obtain the accurate measurement result. Based on the finite element numerical analysis software SEEP/W, setting up the numerical model of filter paper method to analyze water transmission process. And take into account the influence of the hydraulic parameters, initial gravity moisture content and initial dry density of soil on equilibrium time of filter paper method for unsaturated clay. The results show that the dry filter paper will absorb the soil moisture rapidly at the beginning of the test, subsequently, the suction of soil and filter reached balanced state. The equilibrium time judged by moisture content of filter paper (Tw) is shorter than the equilibrium time judged by suction (Tψ). It's suggest that the actual test time is close to Tψ. Generally, the equilibrium time of filter paper is about 4-16 d. The equilibrium time increase greatly for smaller saturated permeability coefficient of soil. The equilibrium time decrease with the increase of the hydraulic parameters (a, n), saturated permeability coefficient, the initial moisture content and initial dry density. On the contrary, the equilibrium time increase with the increase of saturated volumetric moisture content.
  • Particle size distribution characteristics and determination method of crushed gravel with fine content Pc<25% of non-piping permeation deformation type
    QI Junxiu, ZHAO Xiaoju, LIU Yan, ZHANG Zhongyan, ZHANG Guangyu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 977-981. https://doi.org/10.7522/j.issn.1000-0240.2016.0112
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Fine grain content criterion is a main discriminant method for the seepage deformation type of cohesionless coarse grained soil, however the seepage deformation types of fine grain content (Pc<25%) are the soil flow and transitional crushed gravel, which do not conform to the fine grain content criterion. According to the statistical analysis on seepage deformation testing results with 310 specimens from 46 projects (in which, the number of samples (Pc<25%) is 214), although this kind of soil accounts for 6.1% in the same graded section (Pc<25%), the grain grading curves have such an unique characteristic that the grain content of each particle size is uniform. The values of Cu are larger than 5, and most values of Cc are within 1.0-3.0, so this kind of soil are mostly well-graded. Further analysis shows that the ratios of D15/d85 are less than or equal to 5, therefore the D15/d85≤5 is taken as a discriminant method for this kind of soil.
  • Experimental study on shear strength of cemented soil in the acid and alkali conditions
    CHEN Sili, ZHANG Jingyu, SHI Jianjun, HUANG Jie, MENG Jin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 982-987. https://doi.org/10.7522/j.issn.1000-0240.2016.0113
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The relationship curves between the stress deviation(σ1-σ3) and the axial strain(ε) and the shear strength indexes have been obtained after the consolidation-undrained shear tests were carried out in acid and alkali conditions of cemented soil, its security and durability in complex conditions taken as the research background. The tests show that the shearstrength of cemented soil increases gradually with the rise of confining pressures, cemented contents and pH value. So do the cohesion and internal friction angle of cemented soil increase gradually with the rise of cemented contents and pH value. Meanwhile the shear strength equations of cemented soil in different acid and alkali conditions have been obtained. The study results have guiding significance and instructive reference for the security and durability of cemented soil engineering.
  • Experimental study on strength and deformation indicators of frozen silty sand with sodium sulfate
    XU Xiangtian, HE Yang, HU Kai, HAO Ming
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 988-995. https://doi.org/10.7522/j.issn.1000-0240.2016.0114
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Triaxial compressive tests at a temperature of -2℃ have been carried out in terms of saline frozen silty sand with Na2SO4 of 0.5%, while the confining pressure changes from 0.3 MPa to 17 MPa. The results showed that the strength of saline frozen silty sand first increased and then decreased as with increasing confining pressure. The increasing process of strength was divided into two stages, the decreasing rate was 1.775 for first stage while the confining pressure ranged from 0.3 MPa to 4 MPa and 0.753 for second stage while the confining pressure ranged from 4 MPa to 8 MPa. The maximum strength reached 13.10 MPa when σ3=8 MPa and differed by 9.58 MPa from the minimum strength when σ3=0.3 MPa. Variation of the strength was within 13.10 MPa to 12.19 MPa and showed down trend wholly while the confining pressure was within a range from 8 MPa to 17 MPa. To select the reasonable deformation indexes for engineering calculations, the variation of initial tangential modulus E0, secant modulus E0.5, initial tangential Poisson's ratio μ0 and secant Poisson's ratio μ0.5 with confining pressure have been studied, respectively. The change laws of elastic modulus and Poisson's ratio with confining pressure were both divided into three stages by confining pressure (0.3-4 MPa, 4-10 MP and 10-17 MPa). As a result, initial tangential modulus E0 increased as the confining pressure increased in the first and the second stage and decreased from 1 022.39 MPa to 490.27 MPa as the confining pressure increased in the third stage. As to secant modulus E0.5, it increased along with the increasing of confining pressure in the first and the second stage but fluctuated nearby the corresponding value when σ3=10 MPa in the third stage. Poisson's ratio μ0 and μ0.5 decreased with confining pressure increasing in the first and the second stage and increased with confining pressure increasing in the third stage. The initial deformation capacity was more sensitive and the data has intensive discreteness throughout the process. Therefore, being nearly independent of the confining pressure, μ0.5 was suggested to perform engineering computation.
  • The research of chemical methods in improving dredger fill's settlement consolidation properties
    HOU Xin, MA Wei, LI Guoyu, S. K. Nikolaeva, WANG Qing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 996-1002. https://doi.org/10.7522/j.issn.1000-0240.2016.0115
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The dredger fill of Dayaowan port in Dalian city, China is silty clay with high dispersion and low liquid limit. It is mainly characterized with high hydrophilicity, high moisture content and low drainage rate, and in turn, leading to its low bearing capacity, big deformation under load. It can not be used as a kind of architectural foundation soil for a long time. By means of adding different doses of flocculant Praestol-2515 or Praestol-650 with a concentration 0.1% in the salt water, it was observed visually that soil particle flocculated rapidly, and that the interparticles'cement tended to be more uniformly and strongly. The particals turned into flocculus and its size increased, resulting in separation between free moisture and soil particle, and increasing settlement's speed and shortening drainage consolidation time. Consequently, the dredger fill can get enough bearing capacity to serve as a kind of architectural foundation soil.
  • Study on seismic design method for high-speed railway bridge pile foundations considering soil-pile interaction effect
    ZHANG Yongliang, NING Guixia, CHEN Xingchong, DING Mingbo
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1003-1011. https://doi.org/10.7522/j.issn.1000-0240.2016.0116
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In view of the existing questions in seismic design of the high-speed railway bridge pile foundation under strong earthquakes, seismic performance of pile foundation based on multil-evel fortification goal is proposed and the corresponding evaluation index and rational values gived. On the basis of the capacity spectrum method (CSM) put forward in FEMA440 including three kinds of soil-pile interaction effects, foundation flexible effect is simulated by using the curves of p-y, t-z and q-z, while the nonlinearity from pile members is analyzed by PMM hinge, capacity curve of the pier is obtained by pushover. By introducing a seismic demand spectrum modification algorithm from the FEMA440 considering foundation kinematics and damping interaction effects, the modification of demand spectrum is performed. The solving process of ductility demand on pile foundations and performance point is discussed by applying the performance point locus method. With one pier of 32 m simply-supported box girder bridge in high-speed railway as research subject, the feasibility of the method is verified by the case study.
  • The characteristics of dynamic strain amplitude of frozen clay with stepped axial cyclic loading
    LUO Fei, ZHAO Shuping, ZHU Zhanyuan, ZHOU Xiaowan, MAO Lei, QIAN Jin, YU Rui
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1012-1017. https://doi.org/10.7522/j.issn.1000-0240.2016.0117
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The water form in the clay is affected by temperature, consequently affected dynamic strain amplitude of clay. The MTS-810 dynamic triaxial apparatus is used to make researches on the dynamic strain amplitude variation characteristics of frozen clay at a series of temperature. The results show that the dynamic tri-axial test results will be made variable by the instrumental error, operate miss and so on. And the method of repeated trials can be used to eliminate the variability of the test results. The dynamic strain amplitude increases when the load series increases. When the temperature is higher than the freezing point of water in clay, the change of temperature has less effect on dynamic strain amplitude. Inversely, when the temperature is lower than it, the dynamic strain amplitude changes significantly with the decreasing of temperature. When the temperature is lower than -4℃, the relationship curve of dynamic stress amplitude and dynamic strain almost coincide with the decrease of temperature. Dynamic strain amplitude increases linearly with the increase of dynamic stress amplitude.
  • Numerical simulation on seismic response of inclined concrete gravity retaining wall under strong seismic loading
    GAN Fada, CONG Shengyi, TANG Liang, CAI Degou, LING Xianzhang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1018-1027. https://doi.org/10.7522/j.issn.1000-0240.2016.0118
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Firstly, finite element software based on OpenSees, named as "RW_2DPS", which is independently developed and can conduct the seismic response interaction analysis of retaining wall-soil, is introduced. A strong seismic finite element analysis model of inclined concrete gravity retaining wall-soil interaction is established with the aid of this computing platform. In this model, nonlinear finite element analysis method is adopted. The multi-yield surface elastic-plastic constitutive model is chosen to simulate the dynamic properties of sand. Zero length contact element is used to simulate contact characteristic between retaining wall and soil. The consistency dissipative damping boundary is applied to consider lateral boundary effect along the direction of vibration. And velocity boundary of base is used to consider excitation effect on base boundary. At last, random earthquake motions are input on the model base to conduct the seismic response analysis of retaining wall. What is more, gravity retaining wall seismic earth pressure and horizontal seismic inertial force distribution characteristics along wall height are discussed emphatically. It is shown that the of dynamic earth pressure appeared in a third of the wall height. Retaining wall back acceleration present amplification effect, acceleration peak appear at the wall top. Under the action of different ground motions, factor distribution of horizontal acceleration amplification along wall height is different, but dynamic earth pressure peak distribution along wall height is basically consistent.
  • Research on shrinkage characteristics of red clay with drying and wetting cycles
    ZHU Jianqun, GONG Yan, HU Dawei, LI Xiongwei, SHI Weicheng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1028-1035. https://doi.org/10.7522/j.issn.1000-0240.2016.0119
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Shrinkage of red clay with the drying and wetting cycles has profound effects on its engineering properties. It is important for red clay to analyze the effects of numbers of drying and wetting cycles and initial water content. In this paper, laboratory tests were performed on compacted specimens of red clay, which came from a position near a highway constructed in Guizhou. It was found that within a drying and wetting the hoop shrinkage rate would be stable after 6-8 h, and the axial shrinkage rate had a longer time than the hoop shrinkage. The axial linear shrinkage rates of samples with the increase of initial water content during initial test were decreasing, and the hoop shrinkage rates of sample were increasing. The final axial shrinkage and final hoop shrinkage of sample with initial water content of 28% was similar, but the final hoop shrinkage of sample with 34% was higher than the finial axial shrinkage. Although the initial moisture contents had changed a little, the change of the volume shrinkage ratio was significant. It was showed that the effect of drying and wetting cycles on the aggregate of red clay was clear and important. The optimum water content location of the reshaping red clay was independent of the drying and wetting effects. Then, the drying and wetting effects failed to change the maximum adsorption of clay aggregate to absorbed water. It is shown from specimens of the pore size distribution curves acquired by the mercury intrusion pores method that the cycle time has different effect on pores with different diameter. The diameter and distribution density of small pores lied in intra-aggregate had little change, but that of larger pores lied in inter-aggregate was decreasing with the drying-wetting cycles. The micropore structure is corresponding to the shrinkage characteristics of specimens with drying-wetting cycles.
  • Discrete simulation on horizontal character of composite foundation under immersed tube by DEM
    ZHU Xiaojun, LI Wenshuai, FEI Kang, XU Zhaoyang, KONG Weiyang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1036-1043. https://doi.org/10.7522/j.issn.1000-0240.2016.0120
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By particle flow code simulation, the discrete element model of immersed tube under lateral load is established to study the pile's mechanical properties under horizontal loads. The soil displacement field and the stress variation under horizontal load are analyzed, and the macroeconomic factors such as soil particles force chain, coordination number, porosity and angle. From the simulation results that: the immersed tube moves in the horizontal direction under vertical load, particles cushion is disturbed, while increasing vertical load, the range of soil disturbance under immersed tube diminishes. The effect of soil compaction between pile and the range of soil disturbance reduction is more obvious when increase vertical load on immersed tube. According to the research of the strong chain in the pile top soil development law under the immersed tube horizontal movement, the soil particale force chain is variable, the strength force chain and the poor force chain can convert to each other.
  • Extended finite element method analysis for the transient temperature field with phase change
    HE Min, LI Ning, GAO Huanhuan, LIU Naifei
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1044-1051. https://doi.org/10.7522/j.issn.1000-0240.2016.0121
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Transient heat transfer with phase change is the key to the solving of the multi-field coupling problems in cold regions. The freezing process of frozen soil can be divided into four stages based on the measured freezing curves in Changchun. Analyzing the shortage of the traditional finite element method in solving the phase change problem and the characteristic of frozen soil's freezing process, the extended finite element method (XFEM) was proposed for solving the transient heat transfer problem with phase change for permafrost engineering. The XFEM interpolating function and solving format of temperature field with phase change was derived that taking quadrilateral element as an example. Based on the study of the constructing and solving of the level set function, building of the stiffness matrix and subdividing of the elements, a XFEM program for the transient heat transfer problem with phase change was proposed in this paper which has been verified by classical Stefan problem.
  • The bedding sandstone unloading mechanical properties experimental study in the freeze-thaw cycle conditions
    WANG Lehua, JIANG Zhaorong, LI Jianlin, TANG Kaiyu, JIN Jing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1052-1058. https://doi.org/10.7522/j.issn.1000-0240.2016.0122
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    It studies the triaxial unloading mechanical properties of bedding sandstone under two kinds of moisture contents including free water-saturation and vacuum saturation and different freeze-thaw cycle times from 0 to 120 times). It shows that the strength of the sandstone decreases with the increase of freeze-thaw cycle times, and the degree of degradation of vacuum saturation group is more radical than that of free water-saturation group. Appearance damage occurs mainly in the edge of the rock's end and the vicinity of the bedding plane. The axial strain is produced in the stage of loading and residual deformation; and it has good correlation between the reduce of confining pressure and the growth of deformation in the unloading stage. The strain produced in the unloading stage is reduced with the increase of the freeze-thaw times, and unloading effect under the action of freeze-thaw becomes more sensitive. There are certain rules, but no significant, of the effect of the freeze-thaw times to failure mode, and sample destructions are mainly shear failure, but the tensile failure has a tendency to increase with the increase of freeze-thaw times.
  • Analysis of the influence of bedding modified filler and insulation slope protection on temperature field of roadbed in seasonally frozen soil regions
    LU Yonggang, XIAO Hong, CHEN Minzi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1059-1066. https://doi.org/10.7522/j.issn.1000-0240.2016.0123
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    High speed railway requires a high level of ride comfort, the construction of railway facing the problem of subgrade frost heaving in the seasonally frozen soil regions. The deformation of track caused by subgrade frost heaving has seriously affected the safety and comfort of high-speed railway. In this paper, a method for the prevention and treatment of subgrade frost heaving is presented, which uses the cement stabilized grading crushed stones instead of ordinary graded crushed stones as filler in surface layer of subgrade bed and lays insulation slope protection in roadbed side slope, by comparing with other scholars on the subgrade frost heaving prevention and treatment methods. According to the geologic and climate conditions of the seasonally frozen soil regions along the Harbin-Qiqihar Dedicated Passenger Line, using the finite element numerical simulation method to analyze the influence on temperature field of roadbed after laying cement stabilized grading crushed stones in the surface layer of subgrade and laying insulation slope protection in the subgrade slope. And the reliability of finite element numerical simulation results is verified by comparing with the field measurement results of Harbin-Dalian Dedicated Passenger Line. The numerical results show as follows: Replacement of cement stabilized grading crushed stones in the surface layer of subgrade, while laying 3 m high, 2.5 m wide insulation slope protection in the subgrade slope can effectively alleviate the frost heaving, compared with the ordinary subgrade, the maximum freezing depth at the center of subgrade is reduced by 0.5 m, and the maximum freezing depth at the shoulder of subgrade is reduced by 1.1 m.
  • One dimensional thaw settlement of saturated frozen soil
    MING Feng, LI Dongqing, ZHANG Yu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1067-1073. https://doi.org/10.7522/j.issn.1000-0240.2016.0124
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For the frozen soil, the consolidation process is on the basis of the soil melting. Based on the heat conduction equation, which considering water phase change and the moisture migration equation, a thaw-consolidation theory was presented, which take the void ratio as the variable. The effectiveness of this algorithm is verified by the sample application. The void ratio and pore water pressure and deformation with time change law were analyzed, and compared with the experimental results. It was proved that the simulated data have a good agreement with tested results. The results show that the increasing of water content decreased the movement speed of the thawing front. As a result, the rate of consolidation is decreased. The consolidation process lags behind the thawing process. With the thawing front downstairs, the consolidate happens in a larger area. The thaw consolidation process is a process of dissipation of pore water pressure. the deformation is increased with the dissipation of pore water pressure. The deformation increased with the increasing of consolidation degree, and then tend to a stable value, furthermore, the largest displacement appeared at the top end of the soil column.
  • Characteristics of subgrade's temperature, moisture and frost heave deformation in Haomen, passenger railway line from Lanzhou to Xinjiang
    NIU Fujun, LIN Zhanju, WU Xuyang, SHANG Yunhu, LI Xiaolun, SHAO Zhujie
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1074-1082. https://doi.org/10.7522/j.issn.1000-0240.2016.0125
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The safe operation in high-speed railway in cold regions are effected by feeble frost heave of subgrade' carrier with coarse particle and fine particle. Study the characteristics of temperature, moisture and frost heave deformation in different deep of subgrade, based on the 4 fracture surface where installing thermometers, moisture meter and frost heave instrument in different deep of subgrade in Haomen belong to the second line of Lanzhou-Xinjiang railway. The results show that the more sensitive of temperature the more close to the earth's surface, and there is no minus temperature under surface 3 m.The maximum value of frost-heave is 2.1 cm above 2.7 m layer. The deep of 0-0.5 m during the cold season the lowest temperature varies from -10.3℃ to -15.6℃. During warm and initial freezing period, the water content is relatively higher can be reach to 15%, frost heaving ratio is about 4.86 mm·m-1, so grading macadam under the condition of high moisture content and low temperature can effectively weaken the frost heave. The maximum rate of frost heave (14.34 mm·m-1) occurs between 0.5-1.5 m, which layer carrier is ordinary AB group. The lowest temperature varies from -7.2℃ to -12.4℃ in cold season. During warm and initial freezing period, the water content is between 10% and 15%. Between the deep of 1.5-2.7 m layer the frost heaving ratio is about 1.94 mm·m-1, the lowest temperature varies from -3.2℃ to 0.4℃ in cold season. During warm and initial freezing period, the water content is between 12.5% and 15%. The higher content of fine particle the more higher of the frost heaving ratio. Therefore the content of fine particles should be control under 15%.
  • A moving-pump model for moisture and heat transfer during soil freezing
    ZHOU Jiazuo, WEI Changfu, LI Dongqing, WEI Houzhen
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1083-1089. https://doi.org/10.7522/j.issn.1000-0240.2016.0126
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The pulse function was used to transform the flux boundary condition into the source (or sink) term. An imaginary pump located in the freezing front was sucking water from the frozen zone and storing it in a narrow transition zone near the freezing front. The water diffusion equation was divided effectively into two equations in the whole solving domain to avoid the problem of dealing with the moving interface between frozen and unfrozen zone. A sink term was introduced in one dividing equation to express the discharge of water from the unfrozen zone and a source term was introduced in the other dividing equation to express the gathering of water in the frozen zone. The field equations and relations between variables were inputted into the mathematical module of the simulation software COMSOL Multiphysics to model a freezing test of an unsaturated soil sample in closed system, and the simulated results was compared with the experimental and simulated results performed by predecessors.
  • Study on characteristics of seismic peak ground acceleration at permafrost sites along Qinghai-Tibet Engineering Corridor
    SU Yongqi, MA Wei, WU Zhijian, MA Erman
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1090-1098. https://doi.org/10.7522/j.issn.1000-0240.2016.0127
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the results of the seismic hazard analysis of the Beiluhe site and Chumaerhe site along Qinghai-Tibet engineering corridor, artificial bedrock seismic waves with the exceedance probabilities of 1.97%, 1.00%, 0.21%, 0.10%, 0.04%, 0.02% in 1 year were synthesized to use as input waves. One-dimensional model was established by integrating borehole profiles, wave velocities and the existing research results of frozen soil dynamic parameters. Used an equivalent linearity seismic response analysis method, characteristics of site seismic peak ground acceleration(SSPGA) and its influential factors at permafrost sites along Qinghai-Tibet Engineering Corridor (QTEC) were studied. The results show that, (1) peak values and durations of artificial bedrock seismic waves of the Beiluhe site are significantly different from Chumaerhe site, (2) in permafrost site, SSPGA in summer significantly greater than in winter; because the thawed active layer has amplified SSPGA, (3) after frozen in winter, SSPGA decreases with the increase of the frozen soil wave velocity, maximum decrease amplitude is 6.1%, SSPGA decreases with the decrease of Gd/Gdmax and increase of λ, maximum decrease amplitude is 8.9%. The thawing of the active layer has the effect to enlarge SSPGA, so seismic fortification of the major permafrost project should be attached more importance.
  • The limit state of pipeline based on strain design in cold regions
    LI Guoyu, MA Wei, ZHOU Zhiwei, JIN Huijun, ZHANG Peng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1099-1105. https://doi.org/10.7522/j.issn.1000-0240.2016.0128
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Complex geological environment along the pipeline in cold regions, such as landslides, the frost heave and thawing settlement, probably makes the pipe a large differential deformation leading to its failure. Large differential deformation caused by the stress and strain behavior directly affects the safety of pipeline during operation, and even damages the pipe. Based on the actual stress/strain conditions of oil pipeline in cold regions, we fully considered the frost heave, oil pressure and thermal stress effects on the pipeline, and analyzed its factors and the axial tensile strain distribution with different lengths, thicknesses, oil pressures. According to axial strain design criterion, the limit conditions of the oil pipelines were established. The maximum limit of the frost heave deformation for pipelines was obtained. Results show that the stress-based design criteria is conservative, and the strain-based design can use the deformation of the pipes more efficiently. This article can provide references for the reasonable design, safety evaluation and integrity management of pipeline.
  • Strength behavior of frozen fractured ice-filled rock mass and research status of slope instability during thawing
    XU Shuanhai, LI Ning, YUAN Kekuo, WANG Xiaodong, XU Ganggang, WU Boqiang, ZHU Shibin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1106-1120. https://doi.org/10.7522/j.issn.1000-0240.2016.0129
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The slope instability with thawing effect, is a complicated catastrophe process of moisture-heat-stress coupled in frozen fractured ice-filled rock mass. And it has been an important subject in the area of rock mechanics and engineering practice in cold region, what is how to scientifically evaluate its stability and take effective measures to ensure the construction and operation safety of frozen fractured rock slope. So systematic field investigation and experimental study on open-pit mining slope in Muli, Qinghai province have been done. The characteristics of ice occurrence, the ablation characteristics of ice-filled rock formation and the ice thaw-water dissipation characteristics were analyzed, the strength behavior of frozen fractured ice-filled rock mass and open-pit mining slope instability were concluded and summarized. At last, the physical mechanics properties, thermal mechanical coupling of ice-filled rock and stability assessment of the slope with thawing effect at home and abroad were reviewed comprehensively. The study of strength behavior of frozen fractured ice-filled rock mass and open-pit mining slope instability with thawing effect would be a novel research direction, which is equally important to reveal the mechanism of damage development of fractured rock mass under freezing-thawing.
  • Study on in-situ monitoring of moisture and temperature characteristic for the loess cutting slopes
    ZHANG Kun, ZHANG Qinglong, MAO Yuncheng, LI Li, WANG Ruoxu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1121-1128. https://doi.org/10.7522/j.issn.1000-0240.2016.0130
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the field monitoring data, the moisture and temperature variation of the loess cutting slope soil were analyzed. The results showed that the temperature of the soil under the left slope higher than the right side, the freezing period and frozen depth of the left side slope is less than the right. On the right side of the moisture content change depth is larger than the left, the moisture migration rate in more than 5 cm of the shallow soil slope is basically same. The permeability differences in the slopes below 25 cm, the migration rate of the left slope is lower than the right. The temperature of the left slope shallow soil and the right slope soil of the observation area are lower than 0℃ in the winter. The corresponding moisture content of the right slope for more than 25 cm is zero, while the left slope surface shallow soil and right slope below 25 cm are not zero. The significant degree and influence depth of the cutting slope soil for drying-wetting cycles and the freezing-thawing cycles are different.
  • Study on ground temperature of cast-in-place pile of bridge in permafrost regions
    SHANG Yunhu, YUAN Kun, NIU Fujun, WU Xuyang, LI Jinping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1129-1135. https://doi.org/10.7522/j.issn.1000-0240.2016.0131
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the temperature field observation of permafrost around the cast-in-place pile foundation of Chalaping bridge along the Qinghai-Tibet Highway 214, the thermal effects of cast-in-place pile hydration heat are studied and the variation laws of temperature field during refreezing process are analyzed. Results show that: (1) Hydration heat significantly influences the temperature of CA15 and CA14, while slightly disturbs the CA17 with a distance of 2 m to pile. (2) It took 33 days after pile construction, when the negative temperature can be seen on the pile skin. 119 days after construction, the temperature of all pile skin dropped to negative. It took 134 days after construction to refreeze the soil around the pile and 201 days to decrease the pile temperature to natural temperature.
  • Simulation studies of effect in foundation pit cantilever pile of horizontal frost heaving force under negative temperature
    SUN Chao, SHAO Yanhong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1136-1141. https://doi.org/10.7522/j.issn.1000-0240.2016.0132
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Supporting project of foundation pit cantilever pile in cold area, under the horizontal frost heaving force of soil, the pile may be appear these problems, such as tilt, horizontal crack or cut. Negative temperature is key factor of horizontal frost heaving force, with numerical simulation method, simulated silt clay, clay under certain negative temperature change, the size and distribution of pile horizontal frost heaving force, results show that negative temperature is lower, the greater soil freezing rate, the larger horizontal frost heaving force; In the length of pile, horizontal frost heaving force is roughly fluctuation and large middle parabolic distribution, maximum value appeared in the foundation pit of the part, is 0.5-0.8 times depth of excavation, frost heaving force value is 2-15 times to the initial soil pressure. And fitting out formula of maximum horizontal frost heaving force with temperature or displacement of pile top in respectively. In addition, the horizontal displacements of pile increases with decrease of temperature, horizontal displacement caused by frost heave is 0.88 to 11.38 times of excavation displacement in pile top.
  • Experimental study on the loess strength degradation characteristics under the action of dry-wet and freeze-thaw cycles
    LI Li, ZHANG Kun, ZHANG Qinglong, MAO Yuncheng, LI Guoyu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1142-1149. https://doi.org/10.7522/j.issn.1000-0240.2016.0133
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Laboratory experiments were used to simulate the soil seasonal dry-wet and freeze-thaw alternate changes. Using direct shear test to measurement the change of the shear strength and parameters of undisturbed loess after dry-wet and freeze-thaw cycles, and determine the sample total soluble salts after direct shear test. The results showed that: dry-wet and freeze-thaw cycles has a great influence on physical and mechanical properties of undisturbed loess, is the main factor of the loess slope failure. With the increase of dry-wet cycles, the shear strength of the sample decreases, the cohesive force is gradually reduced, internal friction angle first increases, then gradually stabilized, salt migration phenomenon obviously, the lower part of soil soluble salt content gradually reduce, the upper soluble salt content gradually increases, and the mass loss of the sample increased. With the increase of freeze-thaw cycles, the shear strength of the sample decreases, the cohesive force is gradually increased, then gradually stabilized, but the internal friction angle and salt migration phenomenon not obviously.
  • Localized failure mechanism of ground fracture based on structural damage of loess
    SHE Fangtao, MA Chunyang, ZHANG Jundai
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1150-1156. https://doi.org/10.7522/j.issn.1000-0240.2016.0134
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Stuctural damage and fracture of loess strata is caused by the activity of ground fracture. First, bsaed on structural index and stress ratio structural parameter, we establish mathematical model reflecting the initial structure of loess and evolution under coupling of stress and moisture, and analyse variation of tensile strength and compression-shear strength of loess with structure. Second, we establish M-C structure constitutive model of hyper elasto-plasticity which reflects structure evolution of loess. Third, the constitutive model is compiled by Fish language to accomplish inserting FLAC3D explicit finite-difference software. Finally, Stuctural damage and fracture of loess strata under acting ground fracture is very well simulated by the software, and we research on localized failure mechanism of ground fracture of loess strata. Research shows that the evolutionary process of ground fracture in loess zone divided into four stages: initial shear damage stage, initial tensile damage stage, tensile and shear failure development stage, failure surface through stage. Structural evolution of loess is very predominant in the process of progressive failure. The distribution of stress ratio structural parameter under acting ground fracture is consistent with the plastic zones. The results of the research have great significance both in theory sense and engineering practice to understanding the disasters of ground and underground buildings under acting ground fracture.
  • Study on the cold multi-water subgrade protective structure adaptive model based on Renault pad
    WANG Bengang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1157-1166. https://doi.org/10.7522/j.issn.1000-0240.2016.0135
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In this paper, model test was conducted on Renault pad protective engineering of trunk canal slope under frozen soil environment. The establishment of the scale was 1:4 model, twice frozen thaw test during the test of frost heave Renault pad segment surface structure, internal structure thaw process temperature distribution in real time. The results showed that: Renault pad can increase resistance, reduce energy transfer, and lying under the soil temperature field distribution pad, which can effectively reduce the amount of frost depth and frost, and suppress the occurrence of uneven frost heave; in there under sufficient water supply conditions, the maximum amount of frost occurs in the position at the channel bottom on solid feet, followed by 1/3 channel slope, the design should take full account of the position of frost heave deformation; maximum residual deformation in a solid channel bottom foot position, channel slope occurs thaw settlement, Renault pad structure itself has described self-healing function, adapt to freeze-thaw more significant effect of deformation. The design and construction process to be considered stable solid foot.
  • Numerical simulation on anti-jacking-up performance of helical piles of photovoltaic stents in seasonal frozen region
    WANG Tengfei, LIU Jiankun, LIU Xiaoqiang, SHANG Yalong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1167-1174. https://doi.org/10.7522/j.issn.1000-0240.2016.0136
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on custom module of COMSOL, by introducing moisture-heat-stress sequential coupling model established, the jacking-up process of different helical piles under two-dimensional axisymmetric condition is simulated with using smooth pile for contrast. When the frost depth reaches full length of the pile, small-blade helicaled pile performs well in anti-jacking-up (19.5% of that of smooth pile). The embedded thermal stress module is used to simulate the anti-jacking-up process of helical pile under three-dimensional condition, the result of which is compared with laboratory test. The outcome shows that the jacking-up displacement of helical pile with two small blades is the least when the frost depth reaches half the length of the pile. It indicates: the optimal type is picked through numerical simulation, which can provide a reference to the design of helical pile of photovoltaic stents in field test.
  • Study on the simulation of cyclic wetting-drying conditions for rocks in the process of disintegration in drawdown area in reservoirs
    ZHANG Zhenhua, CHEN Shuang, CUI Qiang, HU Yi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1175-1182. https://doi.org/10.7522/j.issn.1000-0240.2016.0137
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Due to the cyclic fluctuation of reservoir water level, rocks in drawdown area are in the cyclic wetting-drying conditions during the course of reservoir operation. In the light of unreasonable simulation of the conditions at present, this paper made moderately weathered purple mudstone from Triassic Badong group in Three Gorges Reservoir under cyclic wetting-drying conditions, measured the masses of matters disintegrating form the mudstone and tested the microstructures of the mudstone and the changes of chemical compositions in soak solution after cyclic wettings for the mudstone The results show that the masses increases no longer after fifth wetting-drying cycle; with the increase of number of wetting-drying cycles, smectite is in decline, which is most obvious in the first wetting-drying cycle and then stable after fourth wetting-drying cycle; the cation exchange capacity almost does not change after the fifth wetting-drying cycles. According to the test results, the simulation time for wetting and drying is determined for the mudstone in drawdown area, namely the wetting time is 4 days and the drying time is 2 days; the mudstone hardly disintegrates after the fifth wetting-drying cycle. Research results can provide reasonable simulation method for cyclic wetting-drying conditions in drawdown area in order to reveal the disintegration mechanism of rocks in drawdown area.
  • Research on damage mechanics of modified-soil in cold regions subgrade coupling action of freeze-thaw and load
    CUI Honghuan, LIU Jiankun, ZHANG Liqun, LI Zhongyu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2016, 38(4): 1183-1188. https://doi.org/10.7522/j.issn.1000-0240.2016.0138
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In this paper, the modified-soil was taken as a research object, the study about the damage evolution equation in terms of freeze-thaw cycle and strain for the freeze-thaw and loaded soil based on micro mechanical mechanism was done. A series of tests were conducted, and the strength and deformation properties of modified-soil subjected to freezing and thawing were analyzed to investigate the freezing and thawing mechanism. And the evolutionary route of micro-structural damage and materials mechanical properties for the modified soil were discussed. The real damage propagation constitutive relation of the freeze-thaw and loaded for modified soil of subgrade was established by using the damage theory of strain equality.
Copyright © Journal of Glaciology and Geocryology, All Rights Reserved.
Tel: 0931-8260767　
E-mail：edjgg@lzb.ac.cn
Total visitors: 　 Visitors of today: 　 Now online:
Powered by Beijing Magtech Co. Ltd,.