突涌地质隧道TSP法弹性参数判识研究

结合云南4座在建高风险隧道典型突涌实例,对不同不良地质发生突涌的地质情况及突涌段落地震波反射法(TSP)的预报成果进行总结,分析各类突涌发生的工程地质条件和地震波反射法物理参数,归纳隧道突涌地质特征,得出大规模突涌时地震波反射法物理参数中纵波速度V_p、横波波速V_s、纵横波速比V_p/V_s和泊松比σ四项参数的判断标准:(1)富水时,V_p/V_s与σ都呈增长趋势,V_p/V_s变化率增长约5%以上,σ变化率增长约10%以上;(2)富水时,V_p/V_s由1.7→2.0变化,σ由0.25→0.3变化;(3)层状裂隙或构造破碎时,V_p均呈下降趋势;(4)存在裂隙及富水通道时,V_s均呈下降趋势;(5)V_p和V_s同时下降时,围岩破碎及地下水发育程度同步上升;(6)V_p上升、V_s下降时,围岩完整程度变化不大,地下水或裂隙发育程度上升。

Study on TSP Elastic Parameter Identification of Tunnel Gushing Geology

Combined with the four typical surge cases in Yunnan high risk tunnel, the geological conditions of different undesirable geological processes and the prediction results of the seismic wave reflection method(TSP) are summarized. The engineering geological conditions and seismic wave reflection method are analyzed, and the geological characteristics of tunnel gushing are summarized. The four parameters of the physical parameters of the seismic wave reflection method, such as longitudinal wave velocity, shear wave velocity, longitudinal and transverse wave speed ratio and Poisson's ratio, are obtained. The judgment criteria are as the followings:(1)when water is rich, V_p/V_s and Poisson's ratio are both increasing, V_p/V_s growth is about 5%, and Poisson's ratio is increased by more than 10%;(2) when water is rich, V_p/V_s changes from 1.7 to 2, and Poisson's ratio varies from 0.25 to 0.3;(3) in case of stratified fracture or structure break, V_p tends to decrease;(4) when there is a fissure and water rich channel, V_s shows a downward trend;(5) when V_p and V_s decrease at the same time, the fragmentation of the surrounding rock and the degree of groundwater development synchronously increase;(6) when V_p rises and V_s drops, the integrity of the surrounding rock changes little, and the development of groundwater or fissure rises.