碎石土滑坡剪切波速度结构分析

Analysis on shear wave velocity of gravel landslide

滑坡体地质结构特征是进行滑坡防护和治理的基本依据,而剪切波速是工程勘察中地层划分及岩土体物理力学性质的重要评判参数。传统地质结构的获取方法 (机械打钻、探井及探槽、PS测井和随钻地震法等)长期以来存在耗时、耗力和费用高昂的问题,且对坡体有一定程度的损伤。本文综合利用多通道瞬态面波法(MASW)和微动勘察法(MSM)在碎石土滑坡上开展数据观测工作,分别利用频域波数法(F-K)和空间自相关法(SPAC)对采集数据进行处理,快速分析了碎石土滑坡的剪切波速度结构。结果表明基于剪切波速的滑坡分层结构与钻探成果相吻合,推测潜在滑动面位于风化千枚岩层内,平均埋深约为50m,起伏形态清晰。剪切波速度结构综合分析实例取得了较好的效果,适用于深层下覆基岩碎石土滑坡的快速勘察。

The geological structure characteristics are the fundamental basis of landslide protection and management,and the shear wave velocity is an important evaluation parameter for the stratigraphic division and rock-soil mechanical properties in geotechnical engineering investigation. The traditional means to acquire the geological structure（ mechanical drilling,exploratory well or trench,PS logging and seismic while drilling etc.） are waste-timely,labor-consuming,costly and a certain degree of damage on the slopes. This paper attempt to observe digital signals with multichannel analysis of surface wave（ MASW）and microtremor survey method（ MSM） on a gravel landslide. Both the frequency wave number method（ F-K） and the spatial autocorrelation method（ SPAC） are used to process the collected signals for the comprehensive analysis of landslide shear wave velocity respectively. The results show that the landslide hierarchy from the above methods coincides with that from the borehole data,and suggest that the average depth of the potential sliding surface is about 50 meters in the strong weathered phyllite rock,and the undulating shape is clear. The example illustrates that the comprehensive analysis of shear wave velocity can assure both the exploration depth and resolution for landslide structure characteristics efficiently.