盾构地中对接冻结加固模型试验(Ⅱ)——冻结过程中地层的冻胀效应研究  

Model test on freezing reinforcement for shield junction in soft stratum(Part2):Frost heave effect of soft stratum during freezing process

作　　者：石荣剑[1,2] 陈斌[3] 岳丰田[1,2] 张勇[1,2] 陆路 

机构地区：[1]中国矿业大学深部岩土力学与地下工程国家重点试验室,江苏徐州221116 [2]中国矿业大学力学与土木工程学院,江苏徐州221116 [3]宁波工程学院,浙江宁波315211

出　　处：《岩土力学》2017年第9期2639-2646,共8页Rock and Soil Mechanics

基　　金：国家高技术研究发展计划(863)计划(No.2012AA06A401)~~

摘　　要：盾构地中对接冻结加固过程中形成不规则形状的冻结体,产生的冻胀效应会引起上部地层产生不均匀冻胀变形。为了获得冻结过程中冻胀效应对上部地层变形的影响规律,以上海地区软土地层中盾构地中对接冻结工程为原型,按照相似理论,设计进行了盾构对接位置地层冻结加固的模型试验,获得了如下结论:冻结过程中,冻胀引起上部地层的变形量随着冻结壁厚度的增长而线性增大,当冻结壁发展超过测点位置后,相应位置的地层变形不再变化。冻结产生的冻胀力对上部地层有压缩作用,随着地层内测点埋深的增加,地层变形量和地层平均应变都逐渐增大。当冻胀力超过土层的黏聚力后,上部土层的滑动使地层平均应变不再增加,地层不再被压缩,下部地层的变形会直接传递到上部地层。研究结果表明,影响冻结加固体上部地层变形量的主要因素是冻结壁的厚度,次要因素是地层的埋深。In general,uneven frost heave deformation was generated in upper soil strata during the freezing reinforcement process of shield junction,which was caused by the frost heave effect of the irregular frozen wall.Hence,this study was to obtain the influence law of strata deformation caused by the frost heave effect.Based on the similarity theory,a model test was carried out according to the prototype of the freezing reinforcement project of shield junction in Shanghai,and then the deformation data were analyzed.The results show that the upper strata deformation caused by the frost heave increases linearly with increasing the frozen wall thickness in the freezing process.When the development of the freezing wall exceeded the measuring point,the stratum deformation at the corresponding position no longer changed.It is found that the frost heaving force caused by the frost heave extrudes the upper strata in the freezing process,which increases both the strata deformation and its average strain with increasing the depth of measuring points.When the frost heave force exceeds the cohesion of soil,the growth of the average strain terminates due to the slide occurrence in upper soil layers.Moreover,the strata are no longer subjected to compress,and the deformation of the bottom stratum transfers directly to the upper strata.The results indicate that the frozen wall thickness is the primary factor and the formation depth is a secondary factor,which both affect the upper strata deformation.

关 键 词：人工冻结 冻胀效应 盾构对接 地层压缩 模型试验 

分 类 号：TU443[建筑科学—岩土工程]