抽水引起的含水层水平应变──地裂缝活动新机理

HORIZONTAL STRAIN OF AQUIFER INDUCED BY GROUNDWATER PUMPING──A NEW MECHANISM FOR GROUND FISSURE MOVEMENT

基于Darcy -Gersevanov广义渗流关系式 ,本文首先导出了单井定流量抽水引起的泰斯承压含水层水平运动和应变解析表达式 ,并据此提出了抽水诱发地裂缝活动的含水层水平应变新机理 ,其主要观点为 :受井栅的约束阻挡作用 ,抽水活动将在含水层内部形成近井径向挤压区和远井径向拉张区两个应变区域 ,随着抽水时间的增长 ,近井径向挤压区将逐渐向外扩展 ;当地裂缝及其下伏断层或裂隙位于抽水活动引起的径向拉张应变区域时 ,地裂缝将出现加速活动 ;反之 ,当地裂缝处于抽水活动引起的径向挤压应变区域时 ,地裂缝活动反而受到抑制。上述地裂缝活动机理通过大同机车工厂现场抽水实验得到了初步证实。

From the Darcy-Gersevanov generalized flow relation between aquifer solid and interstitial water,we firstly present analytical expressions of horizontal aquifer movement and strains induced by constant-volume pumping from a single well in the Thies-Thiem confined system,and then propose a new mechanism for ground fissure movement triggered by ground water pumping. The main view points are under constraint by discharging well screen,an inner radial compression zone and an outer radial tension zone would be formed around the discharging well during pumping.With increasing pumping time the inner radial compression zone would extend outward.Hence,when aa ground fissure or its underlying fault is located in the outer radial tension zone, the movement of ground fissure would be accelerated by groundwater pumping. On the contrary, when the ground fissure is located in the inner compression zone, its movement will reduce with pumping. The new mechanism has been tentatively verified by site pumping experiment at a typical ground fissure of Datong city,China.