饱水红砂岩冻融特性试验研究  

Experimental study of freeze-thaw properties of saturated red sandstone

作　　者：单仁亮[1] 张蕾[1] 杨昊[1,2] 张晋勋[2] 郭志明[1] SHAN Renliang ZHANG Lei YANG Hao ZHANG Jinxun GUO Zhiming(School of Mechanics and Civil Engineering,China University of Mining ＆ Technology,Belling 100083,China Beijing Urban Construction Group CoLtd, Postdoctoral workstation, Beijing 100088,China)

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083 [2]北京城建集团有限责任公司博士后工作站,北京100088

出　　处：《中国矿业大学学报》2016年第5期923-929,共7页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(41572270);中央高校基本科研业务费专项基金项目(2010YL09)

摘　　要：以西北地区多孔隙、易风化典型红砂岩为研究对象,研究冻融作用对红砂岩力学特性影响,分别测定1,2,3次冻融后不同围压条件下,常温/负温红砂岩物理力学参数.试验结果表明:1)3次冻融后,红砂岩表面未产生剥落或开裂现象,但孔隙率和损伤变量增大;2)随冻融次数增加,红砂岩强度和黏聚力逐渐减小,摩擦角增大,负温条件下红砂岩强度和黏聚力始终大于常温条件;3)强度影响系数随冻融次数增加而减小,随围压增加而增大,影响系数大于1时,围压对红砂岩强度的增强作用大于冻融对岩石强度的损伤作用;4)冻融后常温红砂岩压缩破坏主破裂面断面粗糙,有颗粒剥落,产生多条裂纹,破碎严重;负温红砂岩压缩破坏主要为单破裂面剪切破坏,无次裂纹产生.依据以上研究成果,建议冻结工程选用低发热的水泥和炸药,减少冻结壁暴露时间.This paper investigated the influence of freeze-thaw action on mechanical properties of typical saturated red sandstone in northwest China, which had relatively larger porosity and was prone to weathering. Triaxial tests were conducted on red sandstone experiencing one, two and three times of the freeze-thaw cycles under ambient/negative temperature at different confining pressures. The results show that no spalling and cracking on the surface of the specimens is observed after three freeze-thaw cycles, but the porosity and damage variables are increased. Strength and cohesion of red sandstone are reduced with the increase of the freezethaw cycles. Higher values of these parameters are found in negative temperature than the ones in ambient temperature. However, friction angle presents a reverse trend with the temperature variations compared to that of strength and cohesion. The influencing coefficient of strength decreases with the cycle increments, and has an opposite trend with the confining pressure. When the influencing coefficient is larger than one, the effect of confining pressure on enhancing the rock strength is more apparent than the degradation induced by the freeze-thaw. Red sandstone under ambient temperature presents splintery fracture, induced particle peeling, secondary cracks and smashed small blocks, whereas a single plane shear fracture without subor- dinate cracks is dominant under negative temperature. This experimental study indicates that cement and explosives with low emissivity should be used in freezing shaft construction to re duce the exposure time of frost wall.

关 键 词：冻融 冻结 力学特性 饱水红砂岩 围压 

分 类 号：TU457[建筑科学—岩土工程]