深埋隧洞开挖围岩应力演化过程监测及特征研究  

MONITORING AND CHARACTERISTICS STUDY OF STRESS EVOLUTION OF SURROUNDING ROCK DURING DEEP TUNNEL EXCAVATION

作　　者：刘宁[1] 张春生[1] 陈祥荣[1] 侯靖[1] 褚卫江[1] 

机构地区：[1]中国水电工程顾问集团华东勘测设计研究院,浙江杭州310014

出　　处：《岩石力学与工程学报》2011年第9期1729-1737,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51109221);中国博士后基金面上项目(20100471757)

摘　　要：由于TBM掘进不同于钻爆法,其对围岩的损伤程度较轻,不会破坏预埋的空心包体应力计,因此可以在现场预先设计位置埋设空心包体应力计,监测TBM掘进过程中围岩的应力变化。首先利用数值方法计算隧洞开挖后的二次应力分布,分析掌子面效应以及围岩的起裂强度,初步确定围岩的松弛区和损伤区范围,在此基础上确定空心包体应力计的埋设位置和开始监测的时间。然后通过试验洞向TBM掘进隧洞钻孔的方法在松弛区和损伤区分别预埋空心包体应力计,并监测从应力开始变化到最后趋于稳定的整个过程。监测结果证明掌子面效应的存在,应力变化开始于掌子面前大约1倍的开挖洞径,掌子面后0.5倍洞径范围内是应力调整最剧烈的区域,并利用空心包体应力计针对裂纹扩展的敏感性分析围岩损伤区范围,最后根据应力计的监测成果验证此处围岩的起裂强度,监测成果和数值计算结果比较吻合。本文的研究成果可以为现场确定损伤区范围和岩体的起裂强度提供参考,为支护设计和支护时机的选择提供科学依据。The damage caused by TBM excavation is slighter than that by drilling and blasting method.The hollow inclusion stress gauge near the excavation profile cannot be easily damaged.So the hollow inclusion stress gauge can be embedded in designed position of surrounding rock in advance to monitor the stress evolution during TBM driving.Firstly,in order to analyze the tunnel face effect and crack initiation strength of surrounding rock,and confirm the ranges of relaxation zone and damage zone,the stress redistribution after tunnel excavation is calculated by numerical method.Due to the above research results,the embedded position and monitoring start time are both ensured.Secondly,the hollow inclusion stress gauges are installed by drilling from test tunnel to TBM driving tunnel and embedded in relaxation zone and damage zone of the tunnel separately;and the entire process of stress from start changing to be stable is also monitored.The monitoring results affirm the existence of tunnel face effect and show that the stress begins to vary from the one time of tunnel diameter of anterior tunnel face.The region of half of tunnel diameter of posterior tunnel face is the most violent stress redistribution area.The damage zone scope is analyzed through crack propagation sensitivity by hollow inclusion stress gauge.The crack initiation strength of surrounding rock is verified by the monitoring results which well meet the numerical calculation results.The research results can provide references for confirming damage zone scope and crack initiation strength of rock mass.The results can also provide scientific basis for supporting design and selection of supporting time.

关 键 词：岩石力学 深埋隧洞 现场监测 空心包体应力计 应力演化 起裂强度 

分 类 号：TU45[建筑科学—岩土工程]