地下水软化作用下红砂岩变形破坏机理试验研究  

Experimental Study on the Deformation and Failure Mechanism of Red Sandstone under Groundwater Softening

作　　者：张杉 孟陆波[1] 屈小七 李天斌[1] 张煜 ZHANG Shan;MENG Lubo;QU Xiaoqi;LI Tianbin;ZHANG Yu(State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology,Chengdu 610059)

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,成都610059

出　　处：《现代隧道技术》2025年第1期201-211,共11页Modern Tunnelling Technology

基　　金：地质灾害防治与地质环境保护国家重点实验室自主研究课题(SKLGP2022Z003);国家自然科学基金(42130719).

摘　　要：为探究高地应力条件下含水率对红砂岩损伤劣化和变形破坏特征的影响,对4种不同含水率状态下红砂岩进行20MPa高围压下常规三轴试验和三轴蠕变试验。研究结果表明:(1)随着含水率的增加,红砂岩峰值应力、特征应力出现不同程度的降低,扩容应力与峰值应力的比值也降低;含水率高的岩样更早产生新裂隙,也更早发生扩容。(2)岩石含水率为3%时,在加速蠕变阶段,出现随时间增加应变逐渐增大的现象,当应力到达峰值强度后,试件内部的微裂缝在高围压作用下维持“渐进开裂—持续变形”的过程,裂纹缓慢发展最终贯通破坏。(3)基于试验结果,可将地下水对红砂岩渐进开裂—持续变形的软化作用过程划分为3个阶段:阻碍变形阶段(岩石孔隙压密阶段)、促进变形阶段(岩石弹性变形阶段与裂隙稳定发展阶段)、加剧变形阶段(岩石裂隙加速扩展阶段)。To investigate the effects of water content on the damage degradation and deformation failure characteristics of red sandstone under high geostress conditions,conventional triaxial tests and triaxial creep tests were con⁃ducted on red sandstone samples with four different water content states under a high confining pressure of 20 MPa.The results show that:(1)As the water content increases,the peak stress and characteristic stress of red sandstone decrease to varying degrees,and the ratio of swelling stress to peak stress also decreases.Rock samples with higher water content generate new cracks earlier and experience swelling earlier.(2)When the water content is 3%,an ac⁃celerated creep phase appears where strain increases gradually with time.After the stress reaches the peak strength,microcracks inside the specimen maintain a“gradual cracking-sustained deformation”process under high confining pressure,with cracks slowly developing and ultimately leading to failure.(3)Based on the experimental results,the softening effect of groundwater on the gradual cracking and sustained deformation of red sandstone can be divided into three stages:the hindering deformation stage(rock pore compaction stage),the promoting deformation stage(elastic deformation stage and stable crack development stage),and the aggravating deformation stage(rapid crack expansion stage).

关 键 词：红砂岩 地下水软化 含水率 力学特性 持续变形 

分 类 号：U456[建筑科学—桥梁与隧道工程]