结合水对软土次固结特性的影响机制研究  

Mechanism of Bound Water Effects on the Secondary Consolidation Property of Soft Soil

作　　者：吴谦 毛雪松[1] 王常明[3] WU Qian;MAO Xue-song;WANG Chang-ming(School of Highway,Chang’an University,Xi’an 710064,Shaanxi,China;School of Geological Engineering and Surveying,Chang’an University,Xi’an 710054,Shaanxi,China;School of Construction Engineering,Jilin University,Changchun 130026,Jilin,China)

机构地区：[1]长安大学公路学院,陕西西安710064 [2]长安大学地质工程与测绘学院,陕西西安710054 [3]吉林大学建设工程学院,吉林长春130026

出　　处：《中国公路学报》2021年第7期215-225,共11页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(5187081822,41572257);陕西省自然科学基础研究计划项目(2021JQ-244);中央高校基本科研业务费专项资金项目(300102219108)。

摘　　要：结合水对软土的工程特性具有重要影响,为研究结合水对软土次固结特性的影响机制,选取天津软土为研究对象,开展了结合水的等温吸附试验及原状土和不同结合水含量下重塑土的固结蠕变试验。从结合水角度对原状土的固结蠕变特性进行了探讨,并就结合水类型及含量对重塑土蠕变特性的影响机制进行了研究。研究结果表明:等温吸附试验中90%相对湿度节点为土中强、弱结合水的界限,98%相对湿度节点为弱结合水和自由水的界限;相应的,土中强结合水吸附量为13.2%,弱结合水吸附量为22.6%;另外,水化中心的改变导致强结合水阶段吸-脱附过程之间存在明显的滞后效应。原状土固结蠕变过程中,当固结压力p>400 kPa后,土体的次固结受弱结合水控制,此时结合水排水比自由水困难许多,这是原状土次固结系数在400 kPa后开始逐渐减小的原因之一;原状土在整个固结蠕变过程中排出了12.1%的自由水和9%的弱结合水,没有强结合水排出。在强结合水范围内重塑土的次固结变形及次固结系数对结合水量的变化并不敏感,进入强、弱结合水共存状态后,结合水量对重塑土次固结的影响逐渐显现出来,次固结变形量及次固结系数随含水量的增加呈现加速增加的趋势,说明弱结合水是软土固结蠕变的主控因素。Bound water intimately affects the mechanical properties of soft soil.This study reveals the mechanism of bound water effects on the secondary consolidation property of soft soil.Tianjin soft soil was selected as the research object,isothermal adsorption tests and consolidation creep tests of undisturbed and remolded samples with different bound water contents were conducted.The consolidation creep property of undisturbed soil was examined in terms of bound water,and the controlling effects and mechanism of bound water type and content on the creep property of remolded soil were studied.Results of the isothermal adsorption test show that relative humidity HR values of 90%and 98%represent the boundaries between strongly bound,weakly bound,and free water in Tianjin soft soil.Correspondingly,the strongly and weakly bound water contents in the soil are 13.2%and 22.6%,respectively.Variation in the hydration site produces a significant lag effect between the adsorption and desorption processes in the strongly bound water sorption stage.When the consolidation pressure p>400 kPa,the secondary consolidation of the undisturbed sample is controlled by weakly bound water.Because the discharge of bound water is much more difficult than that of free water,the secondary consolidation coefficient of undisturbed soil begins to decrease when p>400 kPa.During the consolidation creep process,the displacement of free water and weakly bound water in the undisturbed sample are 12.1%and 9%respectively,and no strongly bound water is discharged.The secondary consolidation coefficient of remolded samples in the range of strongly bound water is not sensitive to an increase in water content.When entering the coexistence state of strongly and weakly bound water,the effect of bound water on the secondary consolidation of the remolded sample can be observed,and the secondary consolidation coefficient increases rapidly with an increase in water content,indicating that the weakly bound water is the dominant factor to affect the creep property of

关 键 词：道路工程 软土 等温吸附法 结合水 固结蠕变 次固结特性 

分 类 号：U416.1[交通运输工程—道路与铁道工程]