青海那棱格勒抽水蓄能电站深厚覆盖层工程地质特性研究OA

To evaluate the engineering geological characteristics of the deep overburden at Nalinggele Pumped Storage Power Station in Qing-hai Province and their influencing effects on engineering construction,this paper systematically studied the material composition,physical and mechanical properties of the overburden and the potential engineering geological problems through drilling,in-situ tests and laboratory tests.The results show that the overburden in the study area is vertically divided into three layers:①gravelly mixed soil(Qal+pl4),②silty sand(Qal+pl4)and③gravelly mixed soil(Qal+pl3),with significant differences in particle gradation and mainly moderate to strong permeability.The overburden has low bearing capacity and poor foundation uniformity under natural conditions,which is prone to cause uneven settlement.Af-ter the impoundment of the reservoir,the silty sand layer(Qal+pl4)is at risk of seismic liquefaction,and the critical hydraulic gradient of each soil layer indicates a high risk of seepage deformation.To use the overburden as the bearing layer of the dam foundation,anti-seepage rein-forcement and anti-liquefaction measures must be taken to ensure engineering safety.The research results can provide theoretical support and practical reference for the construction of similar projects in deep overburden areas of Qinghai Province.