关键词: 青藏铁路, 高含冰量冻土, 暖季, 路堑爆破

Abstract: In certain circumstances, construction of cuttings in high-ice-content permafrost region in warm season is un-avoided; hence, risk of construction and difficult extent for technology and organization of construction is increased. This article is aimed at introducing the basic principle, process, technology and measures for blasting of high-ice-content permafrost cutting in warm season, taking a typical construction on Qinghai-Tibet Railway as an example;The basic principle for the construction are as follows: 1) to make construction time table in accordance with the characteristics of temperature differences on plateau during day and night, so as to avoid construction under high temperature; 2) to organize the operation in succession and fast-speed, in order to limit the exposure time of permafrost; 3) to facilitate water drainage on the top of cuttings and construction yard in advance based on the principle of "water drainage system first and main construction second"; 4) to carry out cutting blasting on the basis of "it is better over excavation than under excavation" so as to meet the needs of designed thickness of top-soil replacement; Cutting blasting is to be carried out in two layers, i.e. a layer of protection, 2 m in thickness, shall be kept for lessening the interruption to the permafrost foundation base. 5) to carry out cutting blasting without any damage to ecology environment adjacent to facilities or beyond excavation clearance of the railway;Methods for blasting operation: for main excavation, loosening blasting with multiple rows of differential and deep/shallow holes is to be adopted; For gently slopes with high-ice-content permafrost vertical drilling hole blasting is proposed, with cushioned charging structure at the bottom of blasting holes, in order to raise blasting efficiency, speed up the construction and maintain the permafrost slope in good and stable state, meanwhile, attention shall be paid to blasting parameters and depth of drilling holes. Blasting materiel used are 32 No.2 explosive emulsion for rock blasting, 60RYY-Ⅱ explosive emulsion, plastic primacord non-electric detonator system;Technology of construction: construction technology selected is the fundamental part for cutting blasting with high-ice-content permafrost. Its key technology is featured with a word "fast", so, each operation of construction process shall be planed as a whole and tight scheduled without interruption, so as to catch favorable time for the construction.

Key words: Qinghai-Tibet Railway, hight-ice-content permafrost, warm season, cutting blasting