土石混合滑坡体微动探测:以衡阳拜殿乡滑坡体为例

Microtremor survey of soil-rock mixture landslides:An example of Baidian township,Hengyang City

土石混合滑坡体地表地形复杂,土、石混杂堆积,结构松散,探测难度大,目前尚缺乏有效的物探手段.本文首次尝试将小台阵二维微动剖面探测技术应用于衡阳市拜殿乡的土石混合滑坡体探测.探测结果揭示,该滑坡体上部为砂质黏性土层,含块石较多;下为全风化花岗岩层,岩性较为均匀,块石含量少,其顶部为该滑坡体潜在的滑动面.滑动面在滑坡体后缘较陡、中部较为平缓,从而后缘的重力失稳、滑动风险更大.滑坡体的滑床(中-强风化花岗岩、微-未风化花岗岩)埋深在10m以下,起伏变化较大,但岩体相对致密、完整,稳定性好,不易滑动.探测结果与钻探资料较为吻合,为评价滑坡体稳定性、设计合理的治理方案提供了地球物理依据.

The soil-rock mixture landslide is a compound with complex surface topography and loose structure,of which the structure is difficult to detect,and there is no effective geophysical method to solve it so far.This paper documents the first application of the two-dimensional miniature-array microtremor profiling method to detecting the soil-rock mixture landslide in Baidian township,Hengyang City.The results reveal that the upper part of the landslide is a sandy clay layer containing lots of rocks and the under part is completely weathered granite with homogeneous lithology and less rocks.The upper interface of the granite layer is the potential sliding surface of this landslide.As the sliding surface is gentle in the middle but relatively steep in the trailing edge of the landslide,the risk of gravity instability and sliding in the trailing edge of landslide is high.With obvious fluctuations,the depth of the sliding bed（strongly-moderately weathered granite,slightly-non weathered granite）is more than 10 mand its composing rock isrelatively compact,complete,with good stability and not easy to slide.The results of this exploration are consistent with drilling data,providing valid basis for evaluating the stability of the landslide and designing a reasonable landslide treatment scheme.