隧道围岩松动圈的现场测试与理论分析

Field detection and theoretic analysis of loose circle of rock mass surrounding tunnel

围岩松动圈是制定隧道支护措施和整体稳定性评价的重要参数和依据,如何快速准确地确定松动圈范围已备受关注。以张-石(张家口至石家庄)高速公路上的多条隧道工程为背景,采用声波探测和理论计算相结合的方法,对不同埋深、围岩等级条件下的隧道松动圈进行了研究。基于D-P准则推导了围岩应力松动圈的弹塑性理论和损伤理论计算方法,其计算结果均小于单孔声波法测试结果,但两者变化规律类似。由于考虑了岩体的峰后软化特性,损伤理论分析法计算结果比弹塑性理论更加接近于实测值,运用损伤理论对围岩(特别是低级别围岩)松动圈进行预测是可行的,研究结果对其他类似工程具有借鉴作用。

Because the loose circle is an important basis and parameter for designing the tunnel support and estimating whole stability, how to determine its area accurately and fast has become all issues of concern. By taking the tunnels inner highway from Zhangjiakou to Shijiazhuang as study background, the loose circle of tunnels with different overburden depth and rock mass grade was studied by combination of ultrasonic detection and theory analysis. Based on the criterion of Drucker-Prager, the calculation method of theoretic analysis for the loose circle of surrounding rock mass is founded, whose calculated results is lower than those from ultrasonic detection of single hole but has similar variation rules each other. For considering the strain softening after peak strength, the analysis method based on damage theory more approach to results from the field test than the ones of elastoplasticity. The estimation of loose circle of surrounding rock mass with damage theory, especially for low graded rock mass, is feasible. Besides, the study results have some consult effects on the similar engineering. © 2016, Science Press. All right reserved.