基于变形控制的某深埋软岩水工隧洞初期支护参数的选择与验证

Selection and Verification of Initial Support Parameters of a Deep Soft Rock Hydraulic Tunnel Based on Deformation Control

大变形下围岩的稳定控制一直是水利水电、公路、铁路等行业的传统难题,尚未形成一套验证软岩大变形等级下初期支护型式及参数选取的经验方法。依据某深埋水工隧洞工程地质情况,选择典型洞段预测挤压变形风险,利用控制变形估算所需支护力,依据规范和相关工程经验确定支护类型与参数的同时,考虑实际开挖过程利用数值仿真分析验算支护的合理性。结果表明,该隧洞具有极大的大变形风险,采用支护力的方法所确定的支护类型和参数基本合理,可将围岩变形有效控制在规范要求的1.0%~3.0%范围,且锚杆长度及支护应力等均未超过极限强度。

The stability control of surrounding rock under large deformation has always been a traditional problem in water conservancy and hydropower,highway,railway and other industries,and a set of empirical method has not been formed to verify the initial support type and parameter selection under the grade of large deformation of soft rock.According to the engineering geological conditions of a deep-buried hydraulic tunnel,a typical tunnel section is selected to predict the risk of extrusion deformation,the supporting force needed to control the deformation is used to estimate the supporting force,and the supporting types and parameters are determined according to the code and relevant engineering experiences.The rationality of checking support is analyzed by numerical simulation in actual excavation process.The results show that the tunnel has a great risk of deformation,the support types and parameters determined by the supporting force method are basically reasonable,and the surrounding rock deformation can be effectively controlled in the range of 1.0%-3.0%required by the code and the bolt length and support stress do not exceed the limit strength.