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南沟门水库位于陕北黄土高塬南部的黄土梁峁区,坝基为二迭系砂岩夹泥岩、第四系湿陷性黄土及砂砾石等。左坝肩主要工程地质问题是基岩强风化带的渗透问题,防渗帷幕深入岩面以下30 m;坝基存在表层堆积的砂壤土、黄土、古土壤的湿陷问题和下部砂砾石层、基岩强风化带的渗透问题,对湿陷性土层进行工程处理或清除,对砂砾石层采用结合槽截渗处理,防渗帷幕垂直厚度应大于25 m;右坝肩存在斜坡表面土层的湿陷性问题和沿三级阶地砂砾石层、基岩强风化带的绕坝渗透问题,建议翻碾处理湿陷性土层,用砼墙对砂砾石层进行截渗处理,防渗帷幕应深入岩体表面以下20 m。
Nangoumen Reservoir is located in loess ridges in the southern loess plateau of northern Shaanxi. The dam foundation is Permian sandstone mudstone, Quaternary collapsible loess and gravel. The main engineering geological problems of the left abutment dam are the infiltration of the strong weathered zone of bedrock. The seepage prevention curtain goes deeper than 30m below the rock face. The dam foundation has the problems of collapsibility of sandy loam, loess and paleosol accumulated on the surface and lower sand and gravel layer Rock strong weathered zone infiltration problem, the collapsible soil engineering treatment or removal of sand and gravel layer combined with the tank infiltration treatment, the vertical thickness of impervious curtain should be greater than 25 m; the existence of the right dam abutment surface soil layer Collapsibility problems and infiltration around the gravel layer and strong weathered zone of bedrock, it is proposed to roll over the collapsible soil layer and to cut off the gravel layer with the concrete wall, and the seepage curtain should be Depth below the rock surface 20 m.