综合物探方法在输电线路桩基岩溶探测中的应用

Application of Integrated Geophysical Method to Karst Detection of Pile Foundation in Transmission Line

某220 kV输电线路桩基施工过程中,塔腿侧壁遇溶洞导致垮孔。为准确判定该溶洞是否沿桩基底部发育,根据现场地质条件,采用高密度电法与五极纵轴测深法进行综合探测。通过剖面对比分析可以确定,侧壁所遇溶洞沿C腿底部发育,溶洞顶部埋深为9.8 m,高4.5 m,宽约2~3 m,且为独立封闭填充型溶洞。最后通过钻孔验证基本查清了桩基底部溶洞发育情况,为C腿底部溶洞处理提供了可靠的依据。

A tower leg collapse occurred because of the existence of karst cave on the side wall during the pile foundation construction of a 220 kV transmission line.To accurately determine whether the cave is developing along the bottom of the pile foundation,this paper carries out the integrated karst detection by adopting the high density electrical resistivity method and five poles electrical sounding on the basis of field geological conditions.The results show that the cave in side wall of C tower leg is developing along the bottom of the pile foundation through the contrastive analysis.The top of the cave is 9.8 m in buried depth.The caue is 4.5 m in height,and about 2~3 m in width.And the cave is an independent,closed and filled karst cave.Finally,the development of karst cave at the bottom of pile foundation is proved by drilling verification,which provides a reliable basis for processing the karst cave at the bottom of leg C.