咸阳市地下水位动态及其与地裂缝发展的对应关系研究

Research on Dynamic Changes of Groundwater Table and Its Effect on Ground Fissures in Xianyang City

为了明确咸阳市城区地裂缝与地下水开采的关系,在对咸阳市地下水开采历史和现状研究的基础上,根据多年的水位观测资料,研究了咸阳市地下水超采区多年的水位动态变化特征,并结合调查访问和资料收集,对比分析了咸阳市城区地下水开采与地裂缝的定性关系。结果表明:在1986-2006年的快速下降阶段,地下水水位下降了11.4 m;而2006年至今的回升阶段,地下水位上升了6.54 m,目前咸阳市地下水水位已经处于回升和相对稳定的阶段。咸阳城区的地裂缝在1991-2006年高发,2006年之后活动减弱,表明咸阳市地裂缝活动在时间上与抽水引起的地下水位变动具有很好的一致性。同时地裂缝发育的空间分布与抽水形成的水位降落漏斗也具有较好的一致性,说明地裂缝并不是沿渭河断裂全线发育,而是主要发育在城区两个主要的抽水沉降漏斗区,尤以漏斗边缘裂缝更为明显。研究结果对掌握咸阳地裂缝的成因机理,预测其今后的发展趋势,开展地裂缝地面沉降灾害的防治工作具有一定的指导意义。

Most ground fissures in Xianyang City develop along the Weihe Fault.Some experts attribute the occurrence of ground fissures to fault activation.To clarify the relationship between ground fissures and groundwater exploitation in the city,the dynamic change of groundwater level in overpumping areas was analyzed.To summarized the historic and current situation of groundwater exploitation,observation data of groundwater level since 1986 were collected,and relationship between groundwater exploitation and ground fissures was investigated.Results show that the period from 1986 to 2006 the ground water level rapidly declined,during which the groundwater level dropped by 11.4 m,and many ground fissures were formed and developed quickly.Whereas from 2006 to the present,the groundwater level started to bounce back slowly,and the ground fissures turned to stay,indicating that the ground fissure activity in Xianyang city co-worked with the changes of groundwater level by over pumping,and the spatial distribution of ground fissures agreed with the groundwater depression cone.On the other hand,ground fissures did not developed along the whole Weihe Fault,but along the edge of two main groundwater depression cones.Thus,the genetic mechanism of ground fissures in Xianyang city was revealed,and their developing trend could be predicted.This study provides a good instructional guidance to the rational exploration of groundwater and prevention and controls of ground subsidence and ground fissures.