地下硐室围岩应力状态及相关参数测量结果的分析与评价

在深埋及压力硐室工程中,采用水压致裂法测定围岩三维应力状态,宜首先判定围岩应力的分布状况。在具有应力松弛圈、应力集中区与不受开挖影响的正常应力分布域情况下,只有分别进行计算分析,才能更为真实地揭示出硐壁围岩的三维应力分布特征。对于确定压力硐室围岩自身承载能力的水力劈裂测试成果,只有结合裂隙性状、岩层结构状况等进行全面分析,才能准确评价围岩的抗载强度。由于在高压力作用下,岩体中存在的软弱结构面有可能被张裂或扩展,从而改变岩层的透水性,因此只有按照工程运行状态下围岩实际承受的压力进行高压压水测试,才能得到岩层透水性的可靠资料。

ANALYSIS AND EVALUATION OF MEASUREMENT RESULTS OF IN-SITU STRESS STATE AND RELATED PARAMETERS FOR SURROUNDING ROCKMASS OF UNDERGROUND CAVERN

With the development of engineering construction,the buried depth of underground cavern becomes larger and larger.The surrounding rock mass may deform seriously or suffer from rock burst disaster under the high in-situ geostress actions.In order to assure the stability and safety of underground cavern,the measurements and research on the in-situ stress situation,self bearing capacity of rock mass and the permeability of rock mass under high water head actions are specially focused on.For a deep-buried pressure cavern,if the hydraulic fracturing method is adopted to determine the 3D in-situ stress state,it is advisable to define the stress distribution state in the rock mass.Only to calculate and analyze the stress states of stress relaxation zone,stress concentration zone and undisturbed stress zone can reveal the 3D stress distribution characteristics in rock mass around a cavern.For the hydraulic jacking test results to define the bearing capacity of rock mass around the pressure cavern,only the comprehensive analysis including the analysis of joint features and rock mass structures can precisely define the bearing capacity of surrounding rock mass.As the existed weak discontinuity planes in the rock mass may be cracked or expanded under the actions of high pressure,the permeability performance of rock mass is changed accordingly.Therefore,only the high-pressure water test is conducted in accordance with the actual pressures on the rock mass structures under the opeartion state of project to get the reliable data of the rock mass permeability.