高密度电法电性结构揭示天山天池堆积坝体厚度及其阻渗稳水功能分析

天山天池北堆积坝体结构受其成因和演化控制，影响其含水和渗流特性。对该坝体稳定至关重要的下伏基岩埋深、坝体结构阻渗水结构特征等需现场探测并给出科学判断。在地质调查基础上采用高密度电法对天池堆积坝体结构进行探测，首次获得深达下伏基岩的堆积坝体纵向和横向电性剖面。结合光释光测年、水化学成分对比、水量平衡计算等手段，分析坝体堆积物形成时代以及坝体水文地质结构特征。结果显示：天池坝堆积体厚度大于100 m并可分为3层，上部浅表层滑坡形成的巨大块石层厚30～40 m且基本不含水，其下松散含水层厚度为30～50 m;下部为较低电阻率弱透水的冰碛物，主要分布在坝体下游和东端；底部为高电阻率不透水的石炭系火山岩。坝体中间部位地下水集中下渗补给了西小天池。同时靠坝体东侧发育排泄通道，呈现多处溢水点，控制了飞龙涧左岸下降泉季节性发育，同河谷冲刷作用一起影响并导致下游左岸冰碛物中发育4处滑坡体。电法剖面揭示出与坝体轴向近平行的2条隐伏断层，其中堆积坝高堤处气象台所在山丘上游一侧发育一条近东西走向并倾向上游的断层F1,构成地下水阻隔带而使天池堆积坝上游潜水水位呈现一定雍高，同坝体下伏基岩和弱透水冰碛物联合组成的...

Dam Structure and Hydrogeological Conditions of Tianchi Lake in Tianshan Mountains: Perspectives from Electrical Resistivity Tomography and Accumulation Deposit Structure

The accumulation dam structure at the northern exit of Tianchi Lake in Tianshan Mountains is controlled by its origin and evolution, which affects its groundwater hosting and seepage characteristics. The bedrock burial depth and water diversion structure are crucial to the dam stability, which remains unresolved for many years. Based on geological survey, we used electrical resistivity tomography, optical luminescence dating and hydrochemical analysis to detect the structure of Tianchi Lake accumulation dam, and to determine the age of material formation and the hydrogeological features of the dam. The results show that the Tianchi accumulates are over 100 meter-thick, and the upper shallow massive boulder layer and lower aquifer is 30-40 meter and 30-50 meter thick, respectively, which was underlain by igneous rock complex. Groundwater in the middle part of the dam infiltrates intensively and replenishes the western Xiaotianchi Lake. There are many overflow points and discharge channels on the left bank of the Feilong Stream in the east, which control the seasonal occurrence of shallow spring there. An EW-striking fault (inclining to the upstream) is present beneath the hill of the meteorological station, which forms an aquitard in the Tianchi Lake and rises the phreatic water level. The major water diversion structure model (composed of fault and stratigraphic structure) in the accumulation body is preliminarily constructed. We calculated that the groundwater discharge of the Tianchi dam is 1200 m³/d, whilst the total water discharge is 52×10⁴-113×10⁴ m³/d (from winter to summer).