隧道管棚预支护的力学行为及参数优化

Mechanical Behavior and Parameter Optimization of Pipe Roof Reinforcement Applied in Tunnel

基于Pasternak弹性地基梁理论对管棚预支护体系的力学行为进行分析,并与现场测试数据进行对比验证;同时,对不同管棚长度、钢管直径及搭接长度条件下管棚的加固效果进行了分析。结果表明：Pasternak模型能较好地反映管棚在隧道开挖过程中的真实力学行为;管棚的临界长度约为1.5倍开挖高度,当管棚长度超出临界长度后,其对控制开挖面稳定及地层变位的效果不太明显;当钢管直径超过159 mm时,钢管直径的增加对控制开挖面顶部围岩的变形意义不大,目前工程中采用108~159 mm的钢管直径是适宜的。

Based on the Pasternak elastic foundation beam theory,mechanical behavior of pipe roof reinforcement was analyzed.The solutions computed by the proposed analysis were compared with the results of field monitoring.Then,reinforced effects of pipe roof under different reinforcing pipe diameters,pipe lengths,and overlap lengths were analyzed.Results show that Pasternak model can reflect true mechanical behavior of pipe roof in process of tunnel excavation.The critical length of the pipe roof is about 1.5 times of excavated height,if the pipe roof length is longer than critical length,structural advantage due to an increase in reinforcing pipe diameter is unlikely to be significant.The reinforcing pipe diameter of 108 mm to 159 mm applied to the current design practice is suitable.