25 April 2002, Volume 24 Issue 2

    

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  Impact of Freezing and Thawing on Energy Exchange Between the System and Environment

  LI Shu-xun, NAN Zhuo-tong, ZHAO Lin

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 109-115. https://doi.org/10.7522/j.issn.1000-0240.2002.0019

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  On the basis of the solution of the Neumann problem, the surface thermal exchange between environment and the systeminvolved and the temperature gradient inthe range of 0<x<ξ are given, where x is variable of a depth and ξ is depth of active layer. Comparedwith the problem without phase change, the freezing or thawing process increasesthe thermal exchange between environment and the system and the temperature gradient in the range of 0<x<ξ. The classic Neumann problem in freezing and unfreezing regions are expressed in Equations (5)～(7). The energy equilibriumexpressions at thefreezing and thawing front and their combining expression are Equations (8) and (9). The solutions of the problem in the freezing and unfreezing regioncan be expressed as Equations (18) and (19). where β is determined by Equation (26). The thermal flow at x=0 is given by Equation (23). When the system phase does not occur, however, the solution of the problem is given by Equation (11). Meanwhile, the thermal flow at x=0 is representedby Equation (14). Hence, the ratio of thermal exchange between the system and environment (γ) can be expressed as Equation (25). For demonstrating theimpact of freezing and thawing process on thermal exchange between the system and environment, parameters β and γ(the ratio of thermal exchange between the system and environment during freezing and thawing with phase change andduring temperature rising and lowering without phase change) are computed. The computation is performed with several ground soil dataduring freezing and thawing. The computationresults show that γ decreases with system temperature rising and environmental temperature loweringwhen temperatures of the system and environment keep constant in the process of soil freezing; And that γ decreases with system temperature lowering and environmental temperature rising when temperatures of the systemand environment keep constantin the process of soil thawing,; And γ increases with moisture content rising in ground soilor with freezing and thawing speed lowering. The characteristicsof energy exchange between the system and environment during ground soil freezing and thawing process maybe influence climate′s formation and change under naturalconditions at a regional orglobalscale
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  Extraction and Analysis of the Methane Trapped in Ice Core by Melting-Refreezing Method

  XU Bai-qing, YAO Tan-dong, Chappellaz J

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 116-120. https://doi.org/10.7522/j.issn.1000-0240.2002.0020

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  Air was extracted from the bubbles trapped in the Dasuopu ice core by melting-refreezing method, of which the methane was measured. A core sample of a certain depth was cut to four pillars vertically. One pillar, 15 cm in length, was separated into three specimens for repeated measurement. The outer surface of each specimen was removed to eliminate any external contamination. Ice specimen, about 80 g in weight, was melted in an evacuated stainless-steel container sealed with tinfoil, and then a piece of bronze was fitted to the base of the container and soaked into a -60 ℃ alcohol bath. The melted specimen was thus slowly refrozen from the bottom and completely expels the dissolved air. The expelled gas was then expanded into an evacuated sample loop and injected into a Gas chromatograph equipped with a flame ionization detector through a six-port valve. Thus methane was extracted and its concentration can be measured. Blank tests were performed by adding 776 nmul.mol^-1 standard gas to artificial bubble-free ice. The contamination caused by melting appears to be proportional to melting time. However, the contamination is less than 15 nmol×mol^-1 when melting time is within 10 min. In the measurement melting time was controlled within approximately 5～7 min. Therefore, the contamination during the testing was estimated to be 15±4 nmol×mol^-1. The scattering of methane concentrations for three or four injections was ±25 nmol×mol^-1. The agreement between two measurements taken in China (LICCRE) and France (LGGE) was examined at two levels. First, a glass flask filled with LGGE standard gas was measured in LICCRE. Second, an ice sample from the Antarctic D47 ice core, which contains gas since the 1700s and is free of any melt feature, was cut lengthways and analyzed several times in both laboratories. As the preindustrial CH₄ trend was already determined from Greenland and Antarctic ice cores in LGGE using the same technique as for the Dasuopu samples. It is confident that the results presented here can be directly compared to the polar records for determining the difference in CH₄ mixing ratio between sub-tropical and polar latitudes.
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  Influence of Solar Radiation on Embankment Surface Thermal Regime of the Qinghai-Xizang Railway

  HU Ze-yong, QIAN Ze-yu, CHENG Guo-dong, WANG Jie-ming

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 121-128. https://doi.org/10.7522/j.issn.1000-0240.2002.0021

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  Under the assumption of no atmospheric influence on solar radiation transfer, the daily solar radiation amount on railway surface was calculated in one year cycle. Generally the discrepancy of daily solar radiation amount on bothroad-slopes was obviously and varied with season and railway direction. By using the dataset of GAME-Tibet IOP 98 in a fair day in Amdo of the Tibetan Plateau on July 16, 1998, the surface absorptionradiation and some radiation parameters on roadbedand road-slopes were presented. The results show that the daily variation of surface absorptionradiation on both road-slopes varied with railway direction. The discrepancy of surface absorptionradiation between both road-slopes appeared a multi-peak structure in one-day cycle. And the values of these peaksincreased while the railway direction changed from eastward to northward. The discrepancy of daily surface absorptionradiation amount between both road-slopes also varied with railway direction, higher on southeastward railway and lower on northeastward railway. So it is better to construct the railway on tundra region as northeastern direction to reduce the unsymmetrical effect of radiation heating on bothroad-slopes. Further more, the relationship between the railway thermal regime and surface absorptionradiation was linked to design a simple parameterization scheme to retrieve the ground surface temperature on roadbed and both road-slopes.The retrieved ground surface temperature basically agreed the observed one on roadbed. Even so, it is necessary to introduce other variables that affected the ground surface temperature, such as cloud amount, precipitation, air temperature and so on, to improve thisparameterization scheme.
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  Assessment Model of Permafrost Thermal Stability under Engineering Activity

  WU Qing-bai, ZHU Yuan-lin, LIU Yong-zhi

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 129-133. https://doi.org/10.7522/j.issn.1000-0240.2002.0022

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  In this paper a model of thermal stability is put forward, which is expressed by ratio Q_t/Q_t, where Q_t is the total heat of thawing sediment from the bottom of seasonal thawing layer to the potential seasonal freezing depth and the heat spent in temperature rising to 0 ℃ of the bottom seasonal freezing layer, and Q_t is the absorbed heat in the warm season. Based on the monitor data of frozen soil along the Qinghai-Tibetan Highway, the thermal stability model is used to analyze the relationships among thermal stability, mean annual ground temperature, permafrost table temperature and seasonal thawing depth. Analysis results show that thermal stability can well reflect the change of frozen soil under natural state and human activity. Thermal stability has a close relationship with mean annual ground temperature, temperature at the bottom of seasonal thawing layer, and seasonal thawing depth. Permafrost thermal stability linearly changes with permafrost table temperature and mean annual ground temperature Thermal stability increases with mean annual ground temperature decreasing. The higher the MAGT is, the smaller the ratio Q_t/Q_t is. Permafrost is easy changing with environmental factors. The relationship between permafrost thermal stability and seasonally thawing depth is an exponential one. When permafrost thermal stability is stronger, the absorbed heat in warm season can only result in slight thawing in the sediments from the bottom of the active layer to the potential seasonally freezing depth, and is unable to raise the temperature at the bottom of the active layer to 0 ℃. With permafrost thermal stability weakening, the absorbed heat in warm season can result in greatly thawing in the sediments from the bottom of the active layer and the potential seasonally freezing depth, and is able to raise the temperature at the bottom of the active layer to 0 ℃. According to the classification of permafrost stability, permafrost table change and thermal regime along the Qinghai-Tibetan Highway, permafrost can be divided into four types: thermal stable permafrost, transitional thermal stable permafrost, thermal unstable permafrost and extreme thermal unstable permafrost. Thermal stability reflects the change of comprehensive factors of frozen soil and sensitively responds to the change of environmental factors under human activities.
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  A Preliminary Study on Integrating GIS and Environmental Modeling

  LI Shuo, ZENG Zhi-yuan, ZHANG Yun-sheng

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 134-141. https://doi.org/10.7522/j.issn.1000-0240.2002.0023

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  There is a general consensus in both GIS and environmental modeling communities that the advanced integration of GIS and environmental modeling should be promoted. In environmental modeling, populations and species, environmental media, such as air, water, soil, and environmental chemicals are the basic units. Since all the basic units do have a spatial distribution, and this distribution does affect the processes and dynamics of their interactions considerably, GIS is good at dealing with the problem of spatial relationship and spatial distribution. The overlap and relationship between GIS and environmental modeling is apparent, and integration of these two fields is an obvious and promising idea. GIS can be used to account for spatial variability, which is an essential condition for the further development from lumped to spatially distributed models. GIS also can be used to prepare and management input data for environmental models, and their final result can again be used in a GIS as a user-friendly computer presentation. At the same time, environmental models can perform function which, in the main, current GIS lack, but which is important for solving environmental problems. Based on "Integration and Systematization of Mathematic Models for Soil and Water Resources Study in a Basin and Its Application", a NSFC Program, this paper analyzed the integrative relationship between GIS and environmental modeling and pointed out the inevitability of integrating these two research fields. According to the development of GIS technology and the improvement of environmental simulation models, the necessity of integrating environmental simulation models with GIS technology is discussed, and the conceptual framework and the different formats of integration are outlined in this paper.
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  Mean Annual Ground Temperature Distribution on the Tibetan Plateau:Permafrost Distribution Mapping and Further Application

  NAN Zhuo-tong, LI Shu-xun, LIU Yong-zhi

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 142-148. https://doi.org/10.7522/j.issn.1000-0240.2002.0024

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  Mean Annual Ground Temperature (MAGT) is the ground temperature at the depth of a profile where the annual temperature range approximates to zero. The MAGT is one of the main indicators for frozen ground zonation. For getting the MAGT distribution features on the Tibetan Plateau, regression analysis is performed upon 76 observed data series, mainly acquired from boreholes along the Qinghai-Tibetan Highway, based on the relationship among MAGT, latitude and elevation. When multiple correlation coefficient for these data series is 0.90, the relationship is significant. Coupled with TOPO30 Digital Elevation Model (DEM) data, the resulted equation is extended to the whole plateau by GIS to obtain the MAGT distribution on the plateau, a simulated map. Taking the MAGT isotherm of 0.5 ℃ as the boundary of permafrost and seasonally frozen ground, the simulated map is compared with the Map of Frozen Ground on Qinghai-Xizang Plateau^[5], which have been digitized and organized in the same precision as the simulation map. It is found that the simulated map can effectively describe the frozen ground distribution features on the plateau, although there still are differences in individual areas, such as those areas in southeast, which might be caused by insufficient data, complex terrain and other factors. Three applications derived from the simulated MAGT map are then developed. One is for frozen ground zonation. The simulated MAGT map is applied respectively to determine the permafrost zonation indices and the indices for cold region engineering purpose. Every zone’s area is also calculated. One is to determine permafrost thickness distribution on the plateau, based on a simplified thickness calculation equation. A simulated permafrost thickness distribution map is produced as a result. The other is for prediction of permafrost change on the plateau in the future 50 a, with numeric simulation prediction method developed by Prof. Li Shuxun. In the prediction a temperature rising of 0.04 ℃·a^-1 is assumed. The prediction shows that no large-scale degradation will take place, whereas at the edge of permafrost regions manifest degradation will occur.
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  Comparison of Strength and Deformation of Artificially Frozen Soil in Two Testing Manners

  MA Wei, CHANG Xiao-xiao

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 149-154. https://doi.org/10.7522/j.issn.1000-0240.2002.0025

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  With the extensive use of artificial ground freezing technology in construction of mines and deepening of sinking shafts, many engineering accidents occur. A study of frozen soil mechanics in deep alluvium was carried out. The mechanical test method for frozen soil in artificial ground freezing engineering should be first consolidated, then frozen under loading, finally tested (consolidated-frozen-tested or K₀DCF manner). It differs from traditional test method of frozen soil mechanics, which is first frozen without load, then consolidated, finally tested (frozen-consolidated-tested or FC manner). Tests show strength of frozen soil changing with test methods. Based on the traditional test method of frozen soil mechanics, a lot of research results have been obtained. In this paper, the difference between traditional test method of frozen soil mechanics and the test method of frozen soil mechanics in deep alluvium is discussed. Again the relation between the K₀DCF manner and the FC manner is studied, so that the research results in FC manner can be shifted directly to the K₀DCF manner. For providing reliable test basis for studying frozen soil mechanics in deep alluvium and serving to engineering, this paper will probe into differences of strength and deformation between the K₀DCF manner and the FC manner through triaxial compressive tests of frozen sandy soil. It is found that the stress-strain curves have the shape of hyperbola for the two testing manners with different deformation process. The yield strength in the FC manner is obviously less than that in the K₀DCF manner. In the FC manner, the failure strain is obviously greater than that in the K₀DCF manner under loading, and is obviously less than that in the K₀DCF manner under unloading. The Mohr’s envelopes all accord with the Mohr-Coulomb’s criterion within the range of confining pressure in tests. Regardless of state of loading or unloading, the shear strength in the K₀DCF manner is greater than that in the FC manner and with normal stress, the difference of shear strength between loading and unloading in the K₀DCF manner is less than that in the FC manner. Yield strength, failure strain and shear strength in the two testing manners can be joined together through equations (5), (6) and (8).
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  Experimental Study and Numerical Simulation of the Reinforcement of Embedded Freezing Pipes on Artificial Frozen Components

  XIA Hui-min, NIU Fu-jun

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 155-159. https://doi.org/10.7522/j.issn.1000-0240.2002.0026

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  Artificial ground freezing (AGF) brings about high stability, low permeability and economy of artificial frozen components of soil in numerous mining, environmental and foundational projects. Now concerned researchers and engineers have never stopped their steps into the study of applying the AGF on deep pits of soft soil. Meanwhile, it is necessary to point out that the reinforcement of freezing pipes embedded in frozen components has not drawn enough attention, although it will surly increase the economic profits of pit-shoring project. In order to study the reinforcement of embedded freezing pipe on the artificial frozen components, the displacements under different loads were observed through three-point -bend experiment of artificial frozen silt beams. The beam samples were divided into three groups. Group 1 was without any reinforcing articles, Group 2 with embedded freezing pipes and Group 3 with steels. The whole experiment was conducted in the circumstance of -7℃. Corresponding FEM (finite element method) computation was completed applying the MARC software. In the experiment, different failure forms of different groups were performed. A comparative analysis on individual mechanical response caused by whether the component reinforced or not was completed. Based on the experiment on beam components, it is manifested that the freezing pipes increases the strength of frozen components by at least 50% and decreased the displacement by 25% in tendency prediction. The reinforcement in itself will greatly increase economic benefits in artificial freezing shoring projects. That is to say, in practical computation on construction design of pit shoring, whether from the point of view of deformation control or of load control, ignorance of reinforcement of freezing-pipe will increase investment in a project. On the other hand, the comparison between the experimental results and the computed ones has shown a very good agreement both in strength and displacement, which proves the reliability of MARC software in the similar computation.
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  Measuring Total Economic Value of Restoring Ejina Banner’s Ecosystem Services ──Application of the Non-Parametric Estimation

  XU Zhong-min, ZHANG Zhi-qiang, SU Zhi-yong, CHENG Guo-dong

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 160-167. https://doi.org/10.7522/j.issn.1000-0240.2002.0028

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  The contingent valuation method (CVM) is a direct interview approach that can provide an acceptable measure to estimate the economic value of preservation of natural resources. The estimates from the CVM may not be perfect now, however, the estimates from any other economic or physical science model are also imperfect. It is urgent to have an assessment of non-market benefits of restoring Ejina Banner’s ecosystem. In this paper, it is taken as a case to analyze the willingness to pay of restoring ecosystem service.Obtaining accurate benefit estimate from the CVM requires describing the resources in detail. In our survey, The reason why Ejina Banner ecosystem deteriorated and the means by which ecosystem services could be restoring are depicted in another paper. There are three elements in the actual valuation portion: (1) portrayal of the resources to be valued, (2) description of the particular mechanism to be used to pay for the resources, and (3) the question format used to elicit the respondent’s money amount of willingness to pay. Concerning over the influence of institutional and culture setting, payment card is adopted in the investigation. A non-parametric model is employed to estimate the welfare of restoring Ejina ecosystem. Result from 700 in-person interviews indicates that a household would pay ￥43.39 per year on the average, ￥47.59 for the households in the main Heihe River basin, and ￥33.30 for the rest. The aggregate benefit to residents in the main basin is ￥18.39×106 annually. Taking into account the market discount rate, the aggregate benefit of restoring Ejina Banner ecosystem is ￥29.4 ×10⁶ for 20 years. This estimate suggests that the general public in the Heihe River basin would be willing to pay to restoring the Ejina Banner ecosystem. Finally, some suggests are put forward on how to apply the CVM in developing country. It is believed that the CVM may be able to apply more efficiently together with benefit-cost analysis.
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  Study on the Strength Characteristics of Frozen Soil in Artificial Freezing Sinking

  WANG Da-yan, MA Wei, CHANG Xiao-xiao, ZHU Yuan-lin

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 168-172. https://doi.org/10.7522/j.issn.1000-0240.2002.0029

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  With the developing of civil engineering in permafrost regions, frozen soil mechanics have been made great progress in solving general problems in foundation engineering. However, the availability of these theories is still inappropriate to solve the problems in the artificial freezing shaft, because the forming process of artificial frozen soils is different from that of natural frozen soils. The natural frozen soil is formed under frigid climate without pressure, while the artificial frozen soil is formed by artificial refrigerating method with higher loading. In order to simulate the actual freezing and loading process of frozen soil in artificial freezing shaft, experiments on loess were carried out under an artificial controlling condition in laboratory. First, a series of standard soil samples were taken into a pressure chamber to conduct the K-0 consolidation test, then let the temperature drop down to a certain degree, and hold it for 20 h, at last, kept the axial pressure constant and unloaded the confining pressure. The following conclusions can be drawn. The subfreezing temperature and soil depth are the main factors which strongly affect the failure strength and the failure strain of the frozen soil in artificial freezing shaft. The failure strength and the failure strain increase monotonically with the increasing initial confining pressure. Their relations can be described by formulas: (σ₁-σ₃)_f=k₁σ₃+c₁ and ε-1f=k₂σ₃+c₂, where k_XX、c₁、k₂ and c₂ are empirical parameters. The relationship between failure strength and temperature is determined by initial confining pressure. The failure strength is not responsible to the subfreezing temperature at the lower initial confining pressure, but it obviously responds to the subfreezing temperature when it becomes higher. Failure strain depends on temperature fluctuation at any confining pressure. The failure strain in the test decreases with temperature decreasing and presents hyperbola-shaped tendency. At different initial confining pressure, the influence of temperature fluctuation on failure strain is less at the temperature below -7 ℃,and the quadratic equation (ε_1f=Aθ²+Bθ+C) can be used to describe the relationship between failure strain and temperatures fluctuation, where θ is temperature in ℃, A, B and C depend upon initial confining pressure.
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  The Characteristics of Summer Sea Ice and Their Relationship with Climate in the Chukchi Sea

  KANG Jian-cheng, SUN Bo, SUN Jun-ying, MENG Guan-lin, GOTO-AZUMA Kumiko, ZHANG Xiaowei

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 173-180. https://doi.org/10.7522/j.issn.1000-0240.2002.0030

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  Sea ice is the main surface feature of the Arctic Ocean. Sea ice greatly influences the climate in the Arctic. Previous researches showed that the climate change in Arctic during the past 40 a was in disaccord with other areas, especially in summer. It could be the sea ice process, which restricts the effect of global warming on the Arctic Ocean. During August 1999, a sea ice investigation was taken in the Chukchi Sea by the Chinese National Arctic Expedition. Investigation items included sea ice characteristics, such as its distribution, surface features, thickness and floe movement, and temperature fields around the interfaces of air/ice/seawater. Thirteen ice cores were extracted from 11 floes in the area of 72°24′～77°18′ N and 153°34′～163°28′ W. Their structures were observed.Three melting processes of ice were observed: surface layer melting, both surface and bottom layers melting and full melting. The observed temperature fields around floes showed that the bottom melting under floes was an important process. As alternate distribution of floes and open water in the summer Arctic Ocean and large surface albedo difference between ice, about 66%～90%, and water, only 5%～10%, the water under ice was colder than the open water by 0.4～2.8℃. Radiation heated seawater in open water areas and then the warmer water flowed into the ice bottom directly when the floes moved to these areas. This caused melting under the bottom of floe. This process effectively counterbalances the warm wave in all of the Arctic Ocean in summer, thus counteracts the global warming effect in the Arctic Ocean. From the observed structures of sea ice cores, it can be seen that sea ice was composed of ice crystals and brine films. During the ablation period, the brine films between ice crystals melted firstly, then the ice crystals were encircled by the brine-water films, finally the sea ice became a mixture of ice and water, with an ice structure of ice skeleton full of meltwater. At the end of the ablation period, the crystals would be separated each other. At that time, the link between ice crystals greatly decreased. This kind of ice floe would collapse rapidly at the end of ablation.
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  Numerical Analysis of the Temperature Field Features in the Frozen Wall with Double Rows of Freezing Pipes

  WANG Ren-he, CAO Rong-bin

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 181-185. https://doi.org/10.7522/j.issn.1000-0240.2002.0031

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  The freeze time、the thickness of the frozen wall and the temperature field behavior of the frozen wall are the major factors in freezing construction. In the past years detailed analysis about the temperature field behavior of the frozen wall with single row of freezing pipes has been done, and now there have been useful and practical rule and calculation formulas for us to refer to. Following the development of the society, it is urgent to make use of freezing method under double or even more rows of freezing pipes in many practical engineering projects for some special reasons. Nevertheless, the analysis about the development and the changing character of the temperature field in the frozen wall with double or even more rows of freezing pipes is scarce. In this paper, the development and changing features of the temperature field in the frozen wall with single and double rows of freezing pipes are analyzed in detail with the ANSYS Finite Element Calculation Software, referring to one engineering project. Water having different thermal conductivity and different specific heat in two different phases is taken into account in the analysis. Again the thermal exchanging coefficient of the freezing pipes is considered varying with changing temperature contrast. The temperature field behavior under such condition is gotten from the analysis. The conclusion about the superiority of the freezing method under double rows of freeze pipes condition is drawn, that freeze time can be shortened largely, and the freeze efficiency can be improved largely, and the average temperature in the effective thickness of the frozen wall descends largely. This conclusion has significant guidance meaning in choosing the project of freezing construction. The simplified calculation method about the average temperature in the effective thickness of the frozen wall under double rows of freeze pipes condition is discussed in this paper,too.
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  A Study of Water Chemistry and Aerosol at the Headwaters of the Ürüqi River in the Tianshan Mountains

  SUN Jun-ying, QIN Da-he, REN Jia-wen, LI Zhong-qin, HOU Shu-gui

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 186-191. https://doi.org/10.7522/j.issn.1000-0240.2002.0032

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  Aerosol, precipitation, snow and runoff samples were collected from the headwaters of the Ürüqi River from May to June 1996. The measurement of major anions and cations (Cl^-, NO₃^-, SO₄^2-, Ca²⁺, Mg²⁺, Na⁺, K⁺, NH₄⁺), and pH has been made for these samples, except that ammonium has not been done for precipitation samples. pH measurements show that snow and precipitation samples are near to neutral while runoff samples are slightly alkaline. It is found that the sum of measured cations is 2 to 8 fold of measured anions in equivalent unit for aerosol, precipitation, snow and runoff samples. The fact that the measured cations in aerosol exceed the measured anions also suggests that the atmosphere is alkaline over the glacier. According to the previous studies over this area, the missing anion is assumed to be bicarbonate. Thus, bicarbonate and calcium are the dominant anion and cation, respectively, for aerosol, precipitation, snow and runoff samples in this area. The total ionic concentration in various waters is in the order: runoff below the Glacier No. 1>runoff at the control point>runoff below the ice free cirque>precipitation>snow. However, the order of the concentration for different ions is not the same for these waters and aerosol, e.g., Ca²⁺ >Mg²⁺ > Na⁺ >K⁺ >NH₄⁺ for snow and runoff samples, Ca²⁺ >Na⁺ >Mg²⁺ >K⁺ for aerosol and precipitation samples, while HCO₃^->SO₄^2-> Cl^- >NO₃^- for aerosol, precipitation, runoff below the Glacier No. 1 and at the control point, HCO₃^->Cl^- >SO₄^2->NO₃^- for snow and below the ice free cirque. Through the comparison of ionic concentration in different waters, the effect of some processes, such as wet deposition, dry deposition, preferential elution etc, on the certain ionic concentration in the waters is revealed. For example, preferential elution results in lower concentration of SO₄^2- and NO₃^- and dry deposition enhances concentration of Mg²⁺, Ca²⁺ and K⁺ in snow.
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  Theory and Practice of Frozen-soil Blasting in Shaft

  ZONG Qi, MA Qin-yong, WANG Cong-ping

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(2): 192-197. https://doi.org/10.7522/j.issn.1000-0240.2002.0033

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  When a vertical shaft is dug through an unstable topsoil layer, the freezing method is used. However, a situation of the whole section frozen often appears if the frozen-soil layer is too thick. Thus, the digging speed will be heavily lower, because of difficult digging, labor cost and low efficiency. Blasting frozen-soil is an effective method in this situation. In this paper, deformation mechanisms and calculating method of the parameters for cut blasting and smooth blasting of a vertical shaft in frozen-soil are analyzed. The properties and the features of frozen-soil are studied theoretically. Then, on the basis of blasting similarity principles, model tests on cut blasting and smooth blasting in frozen-soil are conducted in laboratory. According to the properties and the features of frozen-soil, blasting parameters were optimized. The results were applied to a frozen-soil blasting engineering. It is found that the drilling and blasting method of shallow holes and more cycles on vertical shaft in frozen-soil is perfect. In this case, more reasonable hole depth is 1.2～1.4 m. For parallel circular cutting and circuit smooth blasting, more reasonable cut blasting parameters are 1.0～1.2 m of diameter of arrangement circle of cut holes, 500～700 mm of hole interval, 2.2～2.8 kg·m^-3 of unit consumption of charge. More reasonable smooth blasting parameters are 500～600 mm of hole interval, 500～700 mm of burden, 0.8～1.2 of density coefficient of holes, and 120～160 g·m^-1 of charge in unit length hole. A decoupling charging structure with air space in radial or axial directions is used. Additionally, because frozen-soil has a large plastic deformation, low explosion velocity and high power explosive should be used in order to raise the effective utilization rate of explosion energy and reduce the damage to circuit frozen-wall. The No.2-water-resistant rock power ammonium nitrate explosive is more available with a good anti-frozen property.