【摘要】 为了研究人工凿井冻结法施工中冻结壁解冻融沉效应的产生而导致井筒壁后附加力的变化,以徐州黏土冻融为研究对象,通过人工冻结土融沉特性试验,分别开展了人工冻土不同含水率、不同单向冻结温度梯度、不同外荷载的冻融特性分析。结果表明:试验系统补水情形下,相同干密度的黏土单向冻结温度梯度为1.4℃/cm时融沉量值为0.98 mm,大于2.0℃/cm融沉量值0.61 mm,增大幅值约60.6%;相同单向冻结温度梯度下,随着外载荷的增大融沉量随之增大,两者增长趋势一致,但幅度不一致。基于对冻土融沉特性受多因素综合影响的认识,采用改进的人工神经网络方法,建立了多样本、多因素影响下的融沉系数关系数据库,误差分析表明,改进的预测算法具有较好的精度。更多还原

【Abstract】 In order to investigate the changes of the additional force in the back of the shaft lining wall, which is caused by the thawing effect of the frozen wall in the construction of the special sinking shaft with freezing method, indoor freeze-thaw cycle tests have been carried out under different moisture contents, unidirectional temperature gradients and external loads, taking Xuzhou clay as the object of study. The results show that: when the test system was under water replenishment, the clay under 1.4 ℃/cm unidirectional freezing gradient has 0.98 mm settlement, which is 60.6% larger than the clay with the same dry density but under 2.0 ℃/cm freezing gradient(with 0.61 mm in settlement). Under the same unidirectional freezing temperature gradient, the thawing settlement increases with the increment of load, of which the increasing trend of is similar while the increasing magnitude is not consistent. Based on the fact that the thawing character of freezing soil is effected by multiple factors, a relational database about thaw settlement coefficient with multi-sample and multi-factor has been built by utilizing the improved artificial neural network. The error analysis certifies that the improved prediction algorithm has greater accuracy.更多还原