低应力水平下颗粒土的边界面本构模型  

A Bounding Surface Model for Granular Soils Under Low Stress Level

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作  者:李书兆 孙国栋 张安 王栋[2] LI Shu-zhao;SUN Guo-dong;ZHANG An;WANG Dong(Beijing Research Center,CNOOC,Beijing 100028,China;Shandong Engineering Research Center of Marine Exploration and Conservation,Ocean University of China,Qingdao 266100,Shandong,China)

机构地区:[1]中海石油(中国)有限公司北京研究中心,北京100028 [2]中国海洋大学海底建设与保护山东省工程研究中心,山东青岛266100

出  处:《地球科学与环境学报》2025年第1期47-55,共9页Journal of Earth Sciences and Environment

基  金:国家自然科学基金项目(42302304,42025702);山东省自然科学基金项目(ZR2022QD017);中国海洋石油集团有限公司“十四五”重大科技项目(KJZX-2022-12-XNY-0100)。

摘  要:低应力条件下土体的力学行为因颗粒嵌锁效应显著增强,表现出更高的摩擦角和剪胀性,工程设计中忽视这些特性可能导致不准确分析甚至引发地质灾害。在SANISAND-04边界面模型基础上进行扩展,通过引入颗粒间嵌锁强度参数,对模型的屈服面、临界状态面、边界面和剪胀面进行了改进,提出了SANISAND-L模型,并采用两种不同嵌锁强度的颗粒土三轴剪切试验结果对该模型进行了验证。结果表明:改进后的SANISAND-L模型只增加了一个模型参数,不仅能准确反映低应力水平下颗粒土的峰值和临界状态内摩擦角的提升,同时也能在较高应力水平下保持适用性;该模型参数能通过低应力条件下的临界状态强度数据直接拟合获得;对模型进行验证发现其显示出较好的预测能力;在2 kPa有效围压下,该模型对Toyoura砂土峰值内摩擦角的预测相对误差低于2%,显著优于未考虑嵌锁效应的SANISAND-04模型(后者相对误差超过25%)。该模型结构简洁、参数标定方便,可在SANISAND-04模型的代码基础上直接修改实现,有助于更加精准地进行浅基础承载力、海底管道铺设等浅部土层工程问题的有限元模拟。Under low-stress conditions,the mechanical behavior of soils is significantly influenced by enhanced particle interlocking effects,leading to higher friction angles and more pronounced dilatancy.Neglecting these characteristics in engineering design may result in inaccurate analyses and even trigger geological hazards.The SANISAND-04 bounding surface model was extended by introducing a particle interlocking strength parameter,modifying the model's yield surface,critical state surface,bounding surface,and dilatancy surface;SANISAND-L model was built and the model was validated using triaxial shear test results on two types of granular soils with different interlocking strengths.The results show that SANISAND-L model with the addition of only one model parameter,accurately reflects the increased peak and critical state internal friction angles of granular soils under low-stress conditions while maintaining applicability under higher stress levels;this model's parameter can be directly calibrated from critical state strength data under low-stress conditions;this model validated demonstrates good predictive capability;for Toyoura sand,at an effective confining pressure as low as 2 kPa,the model achieves a predicted relative error of less than 2%for the peak internal friction angle,significantly outperforming SANISAND-04 model,which has relative errors exceeding 25%.The model features a simple structure and convenient parameter calibration,and can be directly implemented by modifying the code of SANISAND-04 model.It will facilitate more precise finite element simulations of shallow foundation bearing capacity,seabed pipeline installation,and other shallow soil layer engineering problems.

关 键 词:本构模型 颗粒土 理论建模 低应力水平 边界面 嵌锁强度 临界状态 

分 类 号:TU43[建筑科学—岩土工程]

 

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