基于Hoek-Brown强度准则的深部断裂构造岩强度估算

Strength Estimation of Deep Fault Tectonite Based on Hoek-Brown Failure Criterion

西藏某引水隧洞穿越F6断裂带长度达300 m,隧洞埋深110~210 m,常规勘察方法难以对深埋于地下百余米的洞身段断裂带岩体力学性质作出准确的判断。因此,首先利用断裂构造岩浅层原位试验成果,反演Hoek-Brown经验公式计算参数;然后由声波纵波速求得岩体完整性指数Kv,根据断裂构造岩浅层与深层的完整性指数Kv变化来推求GSI指标的变化,采用Hoek-Brown经验公式,对深部断裂构造岩的抗剪强度和变形模量进行了估算。深层构造岩的力学参数计算值与浅层原位测试成果比较,黏聚力提高41.7%,摩擦系数提高10.4%,变形模量提高18.6%,反映了随着岩体完整性的增大,力学参数相应增大的规律,可作为初步设计的依据。勘察实践对在我国西部强烈活动构造地区进行的地下工程有借鉴意义。

A diversion tunnel in Tibet has a length of 300 m through the F6 fault zone in the a depth of 110~210 m.It is difficult for conventional survey methods to accurately judge the mechanical properties of the rock mass in the fracture zone of the cave body buried more than 100 mm underground.Firstly,the results of shallow in-situ test of fault tectonic rocks are used to invert the calculating parameters of the Hoek-Brown empirical formula practical method.Secondly,the rock mass integrity index Kv was obtained from the longitudinal wave velocity of sound wave,and the GSI index change was deduced based on the change of the integrity index Kv of the shallow and deep fault tectonite,and the shear strength and deformation modulus of the deep fault tectonite were estimated by the HoekBrown empirical formula.The calculated mechanical parameters of the deep tectonics were compared with the results of in-situ testing of the shallow tectonics.The cohesion,friction coefficient and deformation modulus were increased by41.7%,10.4%and 18.6%respectively,which reflected the law that mechanical parameters increased with the increase of rock mass integrity,and could be used as the basis for preliminary design.The practical method can be used for reference in the underground engineering in the west of China.