干湿−冻融循环作用下水泥改性膨胀土的路用性能与微观机制  

Performance and micromechanism of cement-modified expansive soils under the influence of freeze−thaw and dry−wet cycles

作　　者：王东星[1] 张子伟 王协群[2] 邹维列[1] WANG Dongxing;ZHANG Ziwei;WANG Xiequn;ZOU Weilie(School of Civil Engineering,Wuhan University,Wuhan 430072,China;School of Civil Engineering and Architecture,Wuhan University of Technology,Wuhan 430070,China)

机构地区：[1]武汉大学土木建筑工程学院,湖北武汉430072 [2]武汉理工大学土木工程与建筑学院,湖北武汉430070

出　　处：《中南大学学报（自然科学版）》2022年第1期306-316,共11页Journal of Central South University:Science and Technology

基　　金：国家重点研发计划项目(2019YFC1509800);国家自然科学基金资助项目(52078400,52079098,51879202)。

摘　　要：通过无侧限抗压强度、动回弹模量、核磁共振、扫描电镜等试验,分析在干湿−冻融循环作用下,水泥改性膨胀土的强度特性与微观结构随初始含水率、水泥掺量、干湿循环和冻融循环次数的变化规律。研究结果表明:随着干湿−冻融循环次数和初始含水率增加,水泥改性膨胀土的抗压强度和动回弹模量降低;随着水泥掺量增大,膨胀土的抗压强度和动回弹模量增大,但水泥掺量存在着临界值;随着干湿、冻融循环次数增加,膨胀土中的大孔隙数量大幅增加,使得膨胀土的强度和动回弹模量降低,而掺加水泥能够有效抑制膨胀土中大孔隙的产生。Through unconfined compression strength test,dynamic resilient modulus test,NMR and SEM technologies,the evolvement rules of strength behavior and microstructure of cement-modified expansive soil with initial water content,cement content and number of freeze−thaw and dry−wet cycles were investigated.The results show that the unconfined compressive strength and dynamic resilient modulus of cement-modified expansive soil decrease with the increase of initial water content and number of freeze−thaw and dry−wet cycles.The unconfined compressive strength and dynamic resilient modulus of expansive soil increase with the increase of cement content,which has a critical value.The quantity of large pores in expansive soil caused by freeze−thaw and dry−wet cycles greatly increases with the increase of freeze−thaw and dry−wet cycle number,which will weaken the unconfined compressive strength and dynamic resilient modulus of expansive soil,while the addition of cement can effectively inhibit the formation of large pores within solidified matrix.

关 键 词：膨胀土 水泥改性 干湿−冻融循环 动回弹模量 微观机制 

分 类 号：TU443[建筑科学—岩土工程]