热-水-力耦合作用下裂隙砂岩渗流和破坏特性研究  

Seepage and failure characteristics of fractured sandstone under thermal-hydro-mechanical coupling

作　　者：刘新荣[1,2] 张馨元 周小涵 张吉禄 王䶮 LIU Xinrong;ZHANG Xinyuan;ZHOU Xiaohan;ZHANG Jilu;WANG Yan(School of Civil Engineering,Chongqing University,Chongqing 400045,P.R.China;Key Laboratory of New Technology for Construction of Cities in Mountain Area,Chongqing University,Chongqing 400045,P.R.China)

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]重庆大学山地城镇建设与新技术教育部重点实验室,重庆400045

出　　处：《重庆大学学报》2025年第3期66-80,共15页Journal of Chongqing University

基　　金：国家自然科学基金资助项目(52374079);国家自然科学基金青年科学基金项目(52104076)。

摘　　要：研究热-水-力耦合作用下粗糙裂隙岩体渗流和破坏特性对探究水热型高地温隧道施工期温度场分布具有重要意义。通过室内热-水-力耦合三轴加荷试验和多物理场耦合数值模拟,分析不同初始岩温(25、50、75℃)和裂隙粗糙度(JRC)影响下砂岩的破坏模式及渗流传热特征。结果表明,1)在热-水-力耦合作用下,完整和裂隙砂岩的应力-应变曲线变化规律和破坏模式基本相同,应力-应变曲线经历初始压密阶段、弹性变形阶段、裂纹稳定扩展阶段、裂纹迅速扩展阶段以及峰后应力5个阶段,且渗透率-应变曲线变化规律与应力-应变曲线规律相呼应。2)预制裂隙的存在使砂岩的峰值强度降低了约7%,峰后应力阶段随JRC值的增加而减小,岩样由延性破坏转变为脆性破坏,而破裂面角度随JRC值的增加而增加,且粗糙裂隙试样从正弦曲线极值点产生剪切破坏。3)裂隙试样的渗透率在加载初期先降低到最小值,经历2阶段增长后渗透率达到最大值,前增长阶段主要渗流路径为岩石基质及预制裂隙,后增长阶段预制裂隙及衍生的细-宏观裂纹进一步拓宽了渗流通道,后阶段渗透率增速是前阶段的3倍。4)在此温况下,温度升高对渗透率初始值和最小值影响显著,对试样强度特性影响较小。Understanding the seepage and failure characteristics of rough fractured rock masses under thermalhydro-mechanical(THM)coupling is crucial for exploring temperature field distribution in hydrothermal high ground temperature tunnels during construction.This study investigates the failure modes and seepage-heat transfer characteristics of sandstone through laboratory THM triaxial loading tests and multi-physical field coupling numerical simulation,considering various initial rock temperatures(25℃,50℃and 75℃)and fracture roughness coefficients(JRC).The main findings are as follows:1)Under THM coupling,the stress-strain curves and failure modes of intact and fractured sandstones are basically consistent.The stress-strain curves exhibit 5 distinct stages:initial compaction stage,elastic deformation stage,stable crack propagation stage,rapid crack propagation stage,and post-peak stress stage.The variation pattern of permeability strain curves correspond to those of stress-strain curves.2)Prefabricated fractures reduce the sandstone’s peak strength by about 7%.The duration of the post-peak stage decreases with the increase of JRC value,shifting failure behavior from ductile to brittle.The fracture surface angle increases with JRC,and rougher fractures are more prone to shear failure originating from the extreme points of sine curve.3)The permeability of the fractured specimen first decreases to its minimum value during the initial loading stage,and after 2 growth stages,the permeability reaches its maximum value.In the early stage,seepage primarily occurs through the rock matrix and prefabricated fractures,while in the later stage,the expansion of prefabricated and newly developed cracks significantly broadens seepage channels,with permeability growth rates approximately 3 times higher than that of the early stage.4)Temperature elevation significantly affects the initial and minimum permeability values but has a limited effect on the strength characteristics of the sample.

关 键 词：热-水-力耦合 裂隙粗糙度 单裂隙砂岩 渗透率 破坏特征 

分 类 号：TU458[建筑科学—岩土工程]