深挖路堑下伏隧道锚围岩承载特性研究

Study on Bearing Characteristics of Surrounding Rock of Tunnel-type Anchorage under Deep Cutting

针对油溪长江大桥北岸开挖路堑下伏隧道锚的特定工程地质背景,为研究该浅埋隧道锚围岩承载特性,通过围岩地质与力学特性评价、工程经验模型预测、有限差分数值模拟和现场模型试验验证的综合研究方法,对隧道锚围岩的变形承载特性开展了系统研究。研究结果表明:工程经验模型预测的承载力结果最低,为10.2倍设计荷载;模型试验加载获得的极限承载力结果达到18倍设计荷载;数值模拟计算得到的承载力结果为11倍设计荷载,与模型试验加载得到的承载力屈服强度结果一致。3种方法综合说明了该隧道锚围岩承载力满足规范对围岩稳定安全系数的要求,且具有一定的优化空间,研究方法及成果可为类似地质条件下的桥梁隧道锚建设提供借鉴。

According to the specific engineering geological background of tunnel-type anchorage under the excavation cutting on the North Bank of Youxi Yangtze River Bridge, in order to study the bearing characteristics of the shallow burying tunnel-type anchorage surrounding rock, the comprehensive research method is used to study the deformation and bearing characteristics of the tunnel-type anchorage. The method includes the evaluation of geological and mechanical properties of surrounding rock, the prediction of engineering experience model, the numerical simulation of finite difference and the verification of field model test. The results show that the prediction result of engineering experience model is the lowest, which is 10.2 times design load. And the ultimate bearing capacity obtained by model test loading is 18 times design load. Furthermore. The bearing capacity obtained by numerical simulation is 11 times design load, which is consistent with the yield strength of bearing capacity obtained by model test. To sum up the above, the three methods comprehensively show that the bearing capacity of tunnel-type anchorage surrounding rock meets the requirements of the specification for the safety factor of surrounding rock stability and has a certain optimization space. In addition, the research methods and results are all example for tunnel-type anchorage construction of bridge under similar geological conditions.