铁路刚构斜拉桥主墩大型基础深切灰岩顺层山坡治理技术

Mountain Slope Treatment Measures for Railway Rigid Cable-stayed Bridge Main Pier Large Foundation in Deep Limestone Bedding

以黔张常铁路长湾澧水大桥2号墩大型基础深切灰岩顺层山坡的加固为依托,通过分析灰岩中软弱夹层的形成、层位及边坡稳定性,确定边坡的治理措施。对灰岩节理发育情况和滑面进行地质调查,结合钻孔判定软弱夹层的层位;再结合边坡稳定性检算,分析边坡的稳定性。研究结果:层面充填泥土的浅层灰岩处于临界状态,遇扰动可能滑动;基坑开挖后,按深层层面抗剪强度检算的边坡稳定系数不能满足要求。优化设计与施工组织,采取降低临空面高度、减少施工因素影响、加固边坡等综合治理措施。

Based on the reinforcement of Changwan-Yinshui Bridge No.2 pier large foundation of deep limestone on Qianjiang-Zhangjiajie-Changde Railway,this paper analyzes the formation and location of the weak interlayer in the limestone and the slope stability,and determines slope treatment measures.Geologic investigation on limestone joint development and sliding surface is conducted and borehole results are used to identify the location of weak layer. The research results show that the surface limestone is in a critical state and any disturbance may lead to land sliding; the slope stability index obtained from shear strength analysis after excavation of foundation pit is not satisfactory. Such comprehensive treatment measures are employed as design and construction procedures optimization,lowering free face attitude,disturbance reduction and slope reinforcement.