基于Q系统与数值模拟的地下岩洞锚喷支护参数研究

Study on Bolt-shotcrete Support Parameters of Underground Rock Cavern Based on Q System and Numerical Simulation

针对山东某地下水封液化石油气库工程,基于洞室截面尺寸和场区结构面发育特征,采用Q系统计算出特定Q值洞室围岩段的初步锚喷参数。基于场区地应力分布特征,采用GSI和Hoek-Brown准则建立起Q值与岩体等效力学参数的联系。基于3DEC离散元,分别从连续和非连续围岩角度对锚喷参数进行校核,并基于超载安全系数法评价支护结构的安全性。结果表明:连续围岩条件下,锚喷支护对围岩位移的控制作用明显,锚杆的最小安全系数为2.75,喷层的安全系数为1.25,表明锚喷参数是安全、合理的;非连续围岩条件下,由于出现局部失稳块体,锚喷支护破坏失效;Q系统不针对局部块体失稳问题,表明结合离散元等数值模拟技术进行综合设计的必要性以及施工期对局部失稳问题进行提前甄别的重要性。

Based on the size of cavern section and the development characteristics of discontinuities, the preliminary boh-shotcrete parameters were obtained for specific Q-value cavern surrounding rock using Q system. A water- sealed liquefied petroleum gas rock cavern in Shandong province was taken as research background. In view of the distribution characteristics of in-situ stress, the relationship between Q value and equivalent mechanical parameters of rock mass were established via GSI and Hoek-Brown failure criterion. Using 3DEC software, the preliminary boh-shotcrete parameters were checked respectively from the aspects of continuous and discontinuous surrounding rocks using 3DEC software, respectively. Moreover, the security safety of support structure was evaluated based on the overloading safety factor law. Results show that： 1 ） when surrounding rock is continuous, the boh-shotcrete support has an obvious effect on the displacement of surrounding rock, and the minimum safety factor of bolt is 2.75,while that of the shotcrete layer is 1.25, which indicate that the boh-shotcrete parameters are safe and rea- sonable; 2） when surrounding rock is discontinuous, the boh-shotcrete support fails due to the local unstability of blocks ; 3 ） since the support object of Q system does not include local unstability block, so it is necessary to adopt discrete element numerical simulation for the support design, and it is important to discriminate local instability problems during construction stage.