不同膨胀潜势等级的膨胀土残余强度环剪试验研究  

Torsional ring shear tests on residual strength of expansive soils with different swelling potentials

作　　者：周葆春 王江伟 单丽霞 李颖 郎梦婷 孔令伟[2] ZHOU Baochun;WANG Jiangwei;SHAN Lixia;LI Ying;LANG Mengting;KONG Lingwei(Henan Unsaturated Soil and Special Soil Engineering Technology Research Center,College of Architecture and Civil Engineering,Xinyang Normal University,Xinyang 464000,China;Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China)

机构地区：[1]信阳师范大学河南省非饱和土与特殊土工程技术研究中心/建筑与土木工程学院,河南信阳464000 [2]中国科学院武汉岩土力学研究所,湖北武汉430071

出　　处：《岩土工程学报》2024年第6期1325-1331,共7页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金面上项目(11772290)。

摘　　要：为探讨不同膨胀潜势等级的膨胀土残余强度与其成分特征的相关性,采用经自主改装的环剪仪开展Denver强膨胀土、荆门中、弱膨胀土环剪试验研究,并与排水反复直接剪切试验结果进行系统对比分析,在此基础上,用实测结果探讨残余强度与土成分特征相关关系的适用性。结果表明:(1)环剪试验测得Denver强膨胀土、荆门中、弱膨胀土有效残余强度内摩擦角分别为11.3°,12.3°,23.7°,比排水反复直接剪切试验测得的低1.7°~3.3°,并无应力相关性且具很好精度,更适于在工程中应用。(2)相关经验关系和公式存在高估或者低估膨胀土有效残余强度内摩擦角的情况。(3)残余强度与土成分特征间定性关系非常明确,上述经验关系对一般土性状况下残余强度预测较为准确;但在土成分复杂状况下,定量准确预测较为困难,这也反映出实测的重要性与必要性。The correlation between residual strength and compositional characteristics of expansive soils with different swelling potentials is investigated.The torsional ring shear tests of Denver expansive soil with high swelling potential and Jingmen expansive soils with medium and low swelling potentials are carried out by using the modified torsional ring shear system,and the results are compared with those of the reversal direct shear tests proposed by the Chinese standard for geotechnical testing method(GB/T 50123-2019).The empirical correlations for the drained residual shear strength suggested by Mitchell and Soga(2005),Stark et al.(2013) and Lehmann et al.(2021) are assessed by the measured results.The conclusions are drawn as follows:(1) The residual friction angles of Denver expansive soil with high swelling potential and Jingmen expansive soils with medium and low swelling potentials measured by the torsional ring shear tests are 11.3°,12.3° and 23.7°,1.7°~3.3° lower than those measured by the reversal direct shear tests and have good accuracy,and are not stress-dependent,which means more suitable for application.(2) Mitchell and Soga(2005) and Stark et al.(2013) overestimate the residual friction angles of expansive soils,while Lehmann et al.(2021) underestimate them.(3) Although the qualitative relationship between the residual strength and the compositional characteristics of expansive soils is perfectly clear,the above empirical correlations are capable to predict the residual friction angles of expansive soils with normal compositions(Jingmen expansive soil with low swelling potentials)correctly.However,it is difficult to predict the residual friction angles of expansive soils with complicated compositions(Denver expansive soil with high swelling potential) quantitatively and accurately.In this case,the torsional ring shear tests are necessary.

关 键 词：膨胀土 残余强度 膨胀潜势 环剪试验 反复直接剪切试验 成分特征 

分 类 号：TU411[建筑科学—岩土工程]