离心机中球形贯入仪贯入黏土特性  

Behavior of ball penetration in clay in centrifuge testing

作　　者：周小文[1,2] 程力 周密[1,2] 王齐 ZHOU Xiao-wen;CHENG Li;ZHOU Mi;WANG Qi(State Key Laboratory of Subtropical Building Science.South China University of Technology,Guangzhou,Guangdong 510640,China;South ChinaInstitute of Geotechnical Engineering,South China University of Technology,Guangzhou,Guangdong 510640,China)

机构地区：[1]华南理工大学亚热带建筑科学国家重点实验室,广东广州510640 [2]华南理工大学华南岩土研究中心,广东广州510640

出　　处：《岩土力学》2019年第5期1713-1720,1730,共9页Rock and Soil Mechanics

基　　金：中国电力建设集团华东勘测设计研究院有限公司科技项目(No.SD2013-10);广东省水利科技创新项目(No.2015-17);广州市2017年科学研究专项重点项目(No.201707020047);中央高校基本科研业务费专项资金项目(No.D2171820)~~

摘　　要：目前球形全流贯入被仪广泛应用于岩土离心试验中,以表征软弱黏土土样的抗剪性能。然而,在离心加速度作用下离心机试验中的球贯入仪比现场使用的标准球贯入仪有更大的加载杆与球的面积比a、更大的等效原型直径以及不一样的球-土摩擦系数,从而使得离心机球体会出现不一样的贯入特性,进而导致不一样的土体抗剪承载力校验系数。通过大变形有限元(large deformation finite element,简称LDFE)方法对中国常见离心机球形贯入仪贯入单层黏土进行分析,获得不同几何尺寸和摩擦系数下球形贯入仪的贯入特性。计算结果通过与有关解析解以及其他前人研究结论的对比分析,验证了有限元分析结果的合理性。通过大量参数分析表明,球摩擦系数对空腔的临界深度以及深层破坏深度的影响较小,面积比a对浅层和深层承载力系数以及达到深层破坏深度有显著的影响。根据数值模拟的结果,提出了不同面积比和摩擦系数下的极限间隙深度Hc、浅层和深层临界破坏模式深度Hd、不同摩擦系数和面积比情况下的深层承载力系数和浅层承载力校准系数的计算公式,从而能获得更精确的土体抗剪强度,为离心机中球形贯入仪的应用提供了理论依据。Full-flow ball penetrometers have been used widely in centrifuge testing for characterizing the undrained shear strength of soil sample. However, the soil flow mechanism and bearing capacity factor of ball penetrometers in centrifuge is significantly different from that of in the field tests, which induced by that the ball-soil frictional coefficient and the ratio of larger shaft diameter and cross-area of centrifuge test is different from that of in field tests. Large deformation finite element analyses are carried out to investigate the behaviour of ball penetrating into uniform clay to quantify the bearing capacity. Prior to conduct parametrical study,the plasticity solutions present good agreement with other previously published finite element results and experimental data. The roughness of ball has little effect on the critical depth of the cavity and the critical deep failure depth. The area ratio is shown to have significant influence on the shallow and deep bearing factors, the critical cavity depth, and the critical deep failure depth. Numerous formulas are proposed to quantify those effects to interpret the undrained shear strength profile, and to provide guidance for its application of ball penetrometers in centrifuge testing.

关 键 词：球形贯入仪 离心模型试验 大变形有限元 抗剪强度 土体流动机制 

分 类 号：TU411[建筑科学—岩土工程]