基于随机介质理论的抽水地表变形时空耦合预测模型

Temporal and spatial coupled predicting model of land deformations caused by groundwater exploitation based on stochastic medium theory

抽取地下水引起的地表变形对地面建(构)筑物的正常使用和结构安全构成了严重威胁。深入研究抽水地表变形预测理论对于沉降灾害防治具有重要意义。由于土体模型选择和土工参数测定上的困难,基于比奥固结理论的数值求解方法在计算抽水地表变形上尚未取得理想效果。文章将随机介质理论与一维固结理论结合,建立了新的抽水地表变形时空预测模型。首先,利用一维固结微分方程,建立反映地面沉降时间效应的半经验计算模型;其次,在分析抽水地面沉降空间分布规律的基础上,利用随机介质理论研究抽水地面沉降空间分布特征;再次,综合考虑抽水地面沉降的时间效应和空间分布形态,建立抽水地面沉降的时空耦合预测模型及抽水地表倾斜、水平移动、水平变形、曲率的时空计算模型。利用这些模型计算地表变形共需5个计算参数,介绍了参数求解方法。最后,利用上述时空耦合计算模型预测某地单井抽水引起地表变形的时空规律。研究表明,所建立的抽水地表变形预测模型能准确地反映抽水地表变形的时空规律,能方便、快捷地预测地下水开采引起的地表变形。

Land deformations caused by groundwater exploitation seriously threaten the safety of people＇ s lives and estates, so it is very important to study the calculating method of land deformations. Because of the difficulties of choosing the soil constitutive model and measuring the parameters, the calculation method based on Biot＇s consolidation theory has not been perfect at present. In this paper, adopting the combination of one dimension consolidation differential equation and stochastic medium theory, a new space-time predicting model of land deformations caused by groundwater exploitation is set up. Firstly, based on one dimension consolidation differential equation, the semi-experience model for land subsidence＇ s time effect is put forward. Secondly, based on analyzing the space distribution laws of land subsidence, by the stochastic medium theory the space distribution calculation model of land subsidence is set up. Thirdly, synthetically analyzing the time effect and the space distribution characteristics, a new time-space predicting model of land subsidence caused by groundwater exploitation is presented, and the time-space prediction models of the surface tilting, the surface level movement, the surface level deformation and the surface curvature are set up. Five parameters are needed when the models perform. Then the physical meanings and calculating method of the four parameters is introduced. Lastly, a case of single dewatering well is introduced, and the time-space laws of land deformations are predicted through the new predicting models. The calculating results show that the predicting model can nicely reflect the time and space characteristics of land deformations caused by groundwater exploitation, and expediently, accurately and rapidly predict land deformations.