纳子峡混凝土面板堆石坝垫层及主堆石区渗透变形室内试验分析

Indoor Test Analysis of Seepage Deformation of Bedding Layer and Main Rockfill Area for Nazixia Concrete Facing Sand-gravel-fill Dam

根据大通河纳子峡面板砂砾石坝的工程特点和料场情况,对纳子峡水电站下游C1料场B、F区及河床的天然砂砾石土料做了筛分试验,绘制了土料的颗粒级配曲线,得出C1料场B、F区土料满足垫层设计要求,且F区土料更优;同理天然砂砾石亦满足主堆石区料设计要求。根据设计要求的颗粒级配、砂土的相对密度、压实度等,对垫层2A1、砂砾石料区3B1土料做了渗透变形试验,发现土料渗透变形破坏均经历了土样保持原状、细颗粒浮动、形成渗漏通道及土样完全破坏4个阶段,绘制了流速—渗透坡降双对数曲线图,据此求得了垫层2A1、主堆石区3B1土料的临界坡降,再根据现行规范取安全系数2.0,从而求得垫层2A1、主堆石区3B1土料允许渗透坡降分别为0.463、0.163。

According to the characteristics of engineering project and the conditions of the quarry for concrete facing sand-gravel-fill dam of Nazixia in Datonghe River, screen analysis test of section B ＆ F at downstream C1 quarry and sand gravel soil material of river bed is implemented. And the grain gradation curves of soil material are plotted. Then the soil materials of section B ＆ F in C1 quarry satisfy the requirements of the bedding layer but the section F is more perfect. Moreover, the sand gravel meets design requirement of main rockfill area quarry. According to the design requirements of grain gradation, relative density of sand soil, degree of compaction, the seepage deformation tests of 2Albedding layer, 3B1 soil materials of sand gravel quarry are carried out. It finds out that the seepage deformation damage of soil material has divided into four stages： soil sample keeping original state, fine grain floating, seepage path forming, soil sample damaging. At the same time, double logarithmic curve between velocity and seepage gradient is plotted. In view of the a bove, the critical gradient of bedding layer 2A1 and 3B1 soil materials in main rockfill area is obtained. According to the current specification, safety factor is given 2.0. So, the allowable seepage gradient of soil material for 2A1 bedding layer and 3B1 main rockfill area are deduced 0. 463 and 0. 163, respectively.