非稳定承压水降水引起土层沉降分布规律分析

Analytical on distribution law of soil settlement caused by unsteady dewatering confined water

摘要:

承压含水层减压降水实质上是一个卸荷过程，其上覆土层沉降可用基于弹性半无限空间Mindlin位移解的推导公式进行计算。分析表明：无限承压含水层非稳定渗流降水时间对土层沉降影响显著；由承压水减压降水引起的土层分层沉降随距地表距离的增加而增大，最大值位于承压含水层顶板处；影响上覆土层沉降的七个参数中：泊松比和承压含水层渗透系数的变化对土层沉降影响很小；上覆土层厚度、承压含水层厚度越大地表沉降值越小；上覆土层弹性模量较小时对地表沉降影响较大，随着弹性模量的增加，其对地表沉降的影响逐渐减弱；地表沉降随单井出水量、承压水水头降深的增大而增加且近似成线性关系；单井出水量、承压含水层厚度、承压水水头降深、上覆土层弹性模量不仅影响地表沉降值的大小还会影响地地表沉降的空间分布。

Abstract:

Decompression and dewatering in confined aquifer is essentially an unloading process, and calculating overlaying soil settlement of confined aquifer can be used to derive formulas based on the elastic half-space of Mindlin displacement solution. Analysis shows that influence of dewatering time of unsteady seepage in infinite confined aquifer on soil settlement is significant compared to the steady seepage. Soil settlement caused by decompression and dewatering of confined water increases with increase of distance from ground and the maximum value emerge on the roof of confined aquifer. In seven parameters affecting ground settlement, influence of Possion’s ration and confined aquifer’s permeability coefficient on ground settlement is very little. Ground settlement will decrease gradually with increase of overlaying soil’s thickness and confined aquifer’s thickness, The influence of elastic modulus on ground settlement is great when its value is small but influence of that gradually weakened with increase of elastic modulus. Ground settlement increase with increase of out-water volume of single well and water head drawdown, furthermore, the relation ship between them nearly to linear relationship, then, out-water volume of single well, confined aquifer’s thickness, water head drawdown and elastic modulus of overlaying soil not only affect value of ground settlement, but also affect the spatial distribution of ground settlement.