关键词: 软岩坝基; 坝基处理; 复合地基; 锚筋桩; 灌注桩; 桥街水电站;

Abstract: The upper tertiary stratum is a kind of micro-diagenetic soft rock stratum,as the foundation of gravity dam,there are problems of compressive deformation and anti-sliding stability.Through engineering geological mapping,combined with various exploration methods such as drilling and geophysical exploration,the upper tertiary stratum of Qiaojie Hydropower Station were divided into fine-grained rock group and coarse-grained rock group.According to the borehole wave velocity,in-situ direct shear,in-situ load and laboratory test,the engineering geological characteristics were analyzed in detail.The research showed that the lithology of the upper tertiary stratum was weak,its deformation modulus,shear strength and bearing capacity were low,its anti-sliding and anti-deformation capacity were poor.The physical and mechanical properties of different rock groups were obviously different due to different particle composition,so it was necessary to carry out the dam foundation treatment.We adopted composite foundation treatment scheme of anchor pile and bored pile combined with consolidation grouting,which could effectively solve the problem of dam foundation compression deformation and anti-sliding stability.The successful experience of Qiaojie Hydropower Station project showed that the composite foundation technology could be applied to dam foundation treatment of water conservancy and hydropower projects,which could improve the anti-sliding and anti-deformation capacity of dam foundation.

Key words: soft rock dam foundation; dam foundation treatment; composite foundation; anchor pile; bored pile; Qiaojie Hydropower station