软岩坝基带状延伸微薄透镜体渗透性改良实践

A Practice About the Permeability Improvement of Tiny Band-Extended Lenses in a Dam Foundation with Soft Rock Mass

某水库坝基基础厚层洪积成因的弱渗透性软岩内存在局部微薄冲积相透镜体,通过半合管双套管钻进获取完整岩芯揭示,尽管其厚度仅有3~17cm,却表现出强透水性的成因是砂砾的组成非常松散。灌浆试验进一步证实了微薄透镜体的带状延伸,在0.4MPa压力下渗透率高达100Lu以上,偶有无压无回流的现象,但是总体的可灌性良好。基础灌浆对微薄透镜体的渗透性成功实现了改良。

There existed in a dam foundation tiny lenses of alluvial phase among soft proluvial deposits rock mass with weak permeability. The cores acquired via semi-casing pipe drilling shew that their big permeability corresponding tiny thickness of 3~17 cm was originated from loose sand and gravel formation. A curtain grouting test testified their banded extension. Some test sections gave permeability more than 100 Lu under 0.4 MPa of pressure, and no pressure and no recirculation occasionally appeared. Nevertheless the test shew that these tiny lenticels can be well grouted. The later foundation grouting succeeded in lowing the permeability of these fine thine lenses.