弥勒原状及压实膨胀土的土水特性及体变特性  

Soil water characteristics and deformation characteristics of mile intact expansive soil and compacted expansive soil

作　　者：王一博 陈锋 潘高峰 何宗弈[1,2] 郑亦轩 袁胜洋 WANG Yibo;CHEN Feng;PAN Gaofeng;HE Zongyi;ZHENG Yixuan;YUAN Shengyang(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China;Key Laboratory of High-speed Railway Engineering of Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China;Railway Engineering Research Institute,China Academy of Railway Sciences Co.,Ltd.,Beijing 100081,China;State Key Laboratory of Geohazard Prevention and Geoenvironmental Protection,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]西南交通大学高速铁路线路工程教育部重点工程实验室,四川成都610031 [3]中国铁道科学研究院集团有限公司铁道建筑研究所,北京100081 [4]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059

出　　处：《铁道科学与工程学报》2022年第11期3266-3274,共9页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51878577);四川省科技计划资助项目(2019YFSY0015)。

摘　　要：为研究弥勒膨胀土的土水特性及体变特性,对弥勒原状及压实膨胀土开展一系列土水特性试验及微观测试试验,并从宏微观角度对原状及压实膨胀土的持水特性和变形特性进行对比分析。研究结果表明:在相同初始含水率和干密度下,原状膨胀土相对于压实土具有更好的持水性能。吸力小于20 MPa时,相同含水率下原状土具有更大的吸力值;吸力大于20 MPa后,原状土与压实土的土水特征曲线基本重合,且压实土具有更高的饱和含水率。对试样的体变测量发现,随着含水率的变化,原状土体变相对压实土较小,但在轴向和径向上的应变二者表现出了相似的规律,即在低含水率时候轴向和径向应变相差不大,当达到一定含水率后(原状土25%,压实土20%)轴向上的应变明显占优。最后,基于扫描电镜试验结果发现,在相同放大倍数下(2 000倍),原状土的孔隙结构较为均匀;而压实土在饱和状态下的孔隙均匀度较差,不仅具有小孔隙,还具有明显的粒间大孔隙及裂隙。且与原状土相比,压实土的颗粒堆积方向性更为明显。基于压汞试验结果发现,在饱和状态下原状土和压实土的孔径分布均为双峰形态,但压实土的宏观孔隙所占比例远大于原状土,二者在极干状态下的孔隙分布情况接近,这也是引起原状土与压实土持水特性和变形特征差异的主要原因。To analyze soil water characteristics and volume deformation characteristics of Mile expansive soil,the article carried out soil water characteristics tests and microscopic tests on Mile intact expansive soil and compacted soil, then analyzed and compared the water retention characteristics and deformation characteristics of intact expansive soil and compacted expansive soil from macro and micro perspectives. It is found that Mile intact expansive soil has better retention characteristics than compacted expansive soil in the same water content.When the suction is less than 20 MPa, the intact soil has greater suction in the same water content. When the suction is greater than 20 MPa, the soil water characteristic curves of intact soil and compacted soil are nearly equal, and compacted soil has greater saturation water content. By measuring the volume change of the samples,it is found that the volume change of intact soil is less than compacted soil, but they have the same regular pattern in the axial dimension and the radial dimension change. The axial dimension and the radial dimension change of intact expansive soil and compacted expansive soil are small when the water content is low. When reaching a certain water content(intact expansive soil 25%, compacted expansive soil 20%), axial dimension varies more.Finally, through the SEM results, it is found that in the same multiple(2 000 times), the pore structure of intact soil is more uniform in saturation condition, while compacted soil has small pores and intra particle big pores and cracks, obviously. Compacted soil has more obvious granular accumulation direction than intact soil. Through the MIP results, it is found that the pore size distribution form both of intact and compacted soil in saturation condition are double peak. The macro pore ratio of compacted soil is more than intact soil in saturation condition,and the pore size distribution is close in limit drying condition. This is the main reason for the difference of water retention characteristics and d

关 键 词：土水特性 体变特性 试验研究 膨胀土 微观分析 

分 类 号：TU43[建筑科学—岩土工程]