竖井地基热排水固结模型试验

Model test on thermal drainage consolidation of foundation with vertical drain

设计竖井热排水固结模型试验系统,选取宁波地区典型软黏土,在室温和水热循环温度70℃下分别开展排水固结和热排水固结模型试验,分析加热、分级堆载、恒载降温阶段各测点的温度、孔隙水压力及地表沉降变化规律。研究结果表明:热排水固结法可加速地基模型的固结速率,固结度达到90%所需时间较排水固结法所需时间减少;经过温度历史后,地表最终沉降量增加,土的抗剪强度有所提高,增强软基处理效果。在试验基础上,分析热排水固结法作用机理,结合已有先期固结压力随温度变化理论,按e-lgp曲线法建立热排水固结法的沉降计算公式,并对竖井模型地表沉降进行计算,与试验结果吻合较好,初步验证公式的合理性。

Model test system was designed for thermal shaft drainage consolidation, and then tests of thermal drainage consolidation and drainage consolidation were carried out by selecting typical soft clay of Ningbo area at room temperature and the hydrothermal fluid circulation temperature of 70 ℃, respectively. The change law of temperature and pore water pressure of each measuring points and ground surface settlement were analyzed for the heating, step loading and cooling（constant load） stage, and the mechanism of thermal drainage consolidation was preliminary elaborated. The results show that the thermal drainage consolidation method can accelerate the consolidation rate of the ground model,and consolidation time required to achieve 90% reduction compared with the drainage consolidation method significantly.After the temperature history, the final settlement of the surface, shear strength increase, and the soft ground treatment effect is enhanced. On this basis of tests, combined with the existing preconsolidation pressure varies with temperature theory, the formula for calculating the subsidence of thermal drainage consolidation method is developed according to e-lg p curve, and theoretical calculations of the ground surface settlement of the shaft foundation are in good agreement with the experimental results, which initially verifies the reasonableness of settlement calculation formula.