孔压影响下坝基开挖岩体卸荷力学特性试验研究  

Experimental Study on Unloading Mechanical Properties of Excavated Rock at Dam Foundation under Influence of Pore Pressure

作　　者：杨冲 陈兴周[1] 黄坚 陈莉丽 王旭 江海 YANG Chong;CHEN Xingzhou;HUANG Jian;CHEN Lili;WANG Xu;JIANG Hai(Department of Civil Engineering and Architecture, Xi'an University of Science and Technology, Xi'an 710054,China;PowerChina Northwest Engineering Corporation Limited, Xi'an 710065,China)

机构地区：[1]西安科技大学建筑与土木工程学院,西安710054 [2]中国电建集团西北勘测设计研究院有限公司,西安710065

出　　处：《西北水电》2021年第4期1-6,共6页Northwest Hydropower

基　　金：国家自然科学基金面上项目(51979218);国家自然科学基金联合基金项目(U1965107);陕西省自然科学基金面上项目(2018JM5118).

摘　　要：坝基开挖及库水渗透作用严重影响重力坝的长期安全运行。以某重力坝坝基开挖卸荷岩体为对象,进行开挖卸荷作用及孔压渗透影响下的室内力学试验,开展了确定同组试样所能承受最大围压的预加载分析,得到了孔压渗透影响下不同卸荷速率条件的应力-应变曲线和分级卸荷应力-体积应变曲线。研究结果表明:卸荷阶段,应力-应变曲线斜率随着卸荷速率增加而逐渐升高;卸荷速率越快,试样发生破坏时的围压值越小,峰值强度提高,弹性模量劣化;相同孔压作用下,卸荷速率越快,孔压渗透量越大,试样侧向体积扩容现象越明显;破坏时产生的张拉裂纹越多,脆性破坏特征显著,孔压渗透降低了试样裂隙面上的有效应力,是加速试样发生破坏的主要因素。The excavation of dam foundation and the seepage of reservoir water seriously affect the long-term safe operation of gravity dam.In this paper,the excavated unloading rock mass of a gravity dam foundation is taken as the study object,and the laboratory mechanical tests considering the excavation unloading action and the effect of pore pressure infiltration are carried out.Based on rock mass structural mechanics,preloading analysis is carried out to determine the maximum confining pressure that the same group of samples can withstand.The stress-strain curves of different unloading rates under the influence of pore pressure infiltration and the stress-volume strain curves of graded unloading are obtained.The results show that:The gradient of stress-strain curve increases gradually with the increase of unloading rate in the unloading stage;the higher the unloading rate is,the smaller is the confining pressure upon the failure of the sample,the peak strength increases and the elastic modulus deteriorates;Under the same pore pressure,the higher the unloading rate is,the greater is the pore pressure permeability,and the more obvious is the lateral volume expansion of the sample;More tensile cracks are generated upon the failure of the sample and the brittle failure characteristics are obvious.The pore pressure infiltration reduces the effective stress on the crack surface of the sample,which is the main factor accelerating the failure of the sample.

关 键 词：坝基开挖 库水渗透 开挖卸荷 分级卸荷 

分 类 号：TU452[建筑科学—岩土工程]