含水层砂土压缩变形特性及数学描述

Compression deformation characteristics of sand in aquifer and its mathematical description

基于 FlowTracⅡ增量固结试验系统,通过控制孔隙水压力设计模拟符合承压含水层砂土应力状态和满足抽水条件应力路径的压缩试验,得到了砂土应变与时间关系曲线,探讨分析不同抽水模式作用对含水层砂土压缩变形特性的影响。试验结果表明:在抽水作用下,砂土压缩变形具有非线性和时效性特征;在相同前期固结压力下,砂土压缩变形量随着抽水强度的增加而增大,且变形稳定所需时间也越长;在稳压抽水作用下,砂土的应变率与时间在双对数坐标中呈现较明显的线性关系,其斜率受抽水强度和抽水速率的影响。建立了考虑抽水强度和抽水速率影响的砂土压缩变形与时间、应力的归一化经验公式。研究成果揭示了不同抽水模式下含水层砂土的压缩变形特性,为合理评价抽水引起的地面沉降提供试验依据。

Based on the FlowTrac II incremental consolidation system, compression tests by the control of pore pressure were designed to meet the stress state and the stress path of the sand in the confined aquifer. The relationship between strain-time and the sand was obtained. The effects of different water pumping modes on the compression deformation characteristics of the sand in aquifer were discussed. Results showed that the compression deformation of the sand under water pumping was nonlinear and time-dependent. Under the same pre-consolidation pressure, the compression deformation of the sand increased with the increase of water pumping intensity, and the time for the sand to stabilize was longer. Under the stable water pumping modes, the relationship of strain rate-time showed linear in the double logarithmic coordinate and the slop was affected by the water pumping intensity and rate. Considering the water pumping intensity and rate, a normalized empirical formula of compression deformation, time and stress was established. The results revealed the compression deformation characteristics of the sand under different water pumping modes and provided experimental basis for the reasonable evaluation of land subsidence caused by extracting groundwater.