大藤峡水库岩溶塌陷预防的安全调度研究

Study on the safe operation of karst collapse prevention in Datengxia reservoir

水库运行容易在库区诱发滑坡、岩溶塌陷等地质灾害。通过水库运行的安全调度,可有效减少库区地质灾害的发生。本文以在建的大藤峡水库武宣防护区为例,分析计算了岩溶塌陷预防的安全调度水位、排蓄水速度;并根据现场调查,查明了研究区岩溶塌陷发育的地质背景和发育现状,建立了岩溶塌陷发育机理模式。为了分析水库运行改变地下水动力条件对岩溶塌陷发育的影响,运用Modflow软件,建立研究区数值模拟模型,通过数值模拟运算,预测了大藤峡水库不同蓄水水位引起的地下水位变化,以及不同排蓄水速度引起的地下水流速变化;探讨了包气带、潜水层和承压水层区域岩溶塌陷发育的可能性。结果表明:研究区岩溶塌陷预防的水库安全水位高程为51~62m,蓄水水位安全上升速度为0~1.0m·d^(-1)和排水水位安全下降速度为0~3.0m·d^(-1)。

Reservoir operation is easily to induce landslide, karst collapse and other geohazards in the reser- voir area. The safe operation of a reservoir can effectively reduce the occurrence of geological disasters. Taking the Datengxia reservoir under construction as an example, this paper presents the prevention to karst collapse through reservoir safe operation. According to the field investigation, the mechanism model of karst collapse development is established, based on the analyses of geological information and developing situation of the karst collapse in the study area. In order to analyze the effect of groundwater dynamic due to reservoir operation on the karst collapse, the Modflow software is used to conduct the numerical simulation. Through the numerical simulation, both of the change of groundwater level caused by the fluctuation of reservoir water level and the change of groundwater velocity induced by the impoundment or drainage of Datengxia reser- voir are predicted. As the results, safety water level of theDatengxia reservoir is 51--62 m to prevent karst collapse in Wuxuan protection region, the safe impoundment speed of water level is 0--1.0 m · d -1 , and the safe drainage speed of water level is 0--3.0 m · d -1.