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Critical state shear behavior of the soil-structure interface determined by discrete element modeling

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Particuology 2017年第6期15卷 68-77页

作者： Xiaoqiang Gu Yuanwen Chen maosong huang Department of Ceotechnical Engineering Tongii University Shanghai 200092 China Key Laboratory of Ceotechnical and Underground Engineering of the Ministry of Education Shanghai 200092 China

The interface between soil and structure can be referred to as a soil-structure system, and its behavior plays an important role in many geotechnical engineering practices, In this study, results are presented from a series of monotonic direct shear tests performed on a sand-structure interface under constant normal stiffness using the discrete element method （DEM）. Strain localization and dilatancy behavior of the interface is carefully examined at both macroscopic and microscopic scales. The effects of soil initial relative density and normal stress on the interface shear behavior are also investigated, The results show that a shear band progressively develops along the structural surface as shear displacement increases. At large shear displacement a unique relationship between stress ratio and void ratio is reached in the shear band for a certain normal stress, indicating that a critical state exists in the shear band. It is also found that the thickness and void ratio of the shear band at the critical state decreases with increasing normal stress. Comparison of the DEM simulation results with experimental results provides insight into the shear behavior of a sand-structure interface and offers a means for quantitative modeling of such interfaces based on the critical state soil mechanics.

关键词： Discrete element method Interface Direct shear test Shear band Dilatancy Critical state

Centrifuge study on behavior of raft foundation after tunnelling in soft clay

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Underground Space 2024年第4期17卷 161-169页

作者： Jian Yu Jiaming Liu Chun Fai Leung maosong huang Qi Wen Jorgin Tan Department of Geotechnical Engineering Key Laboratory of Geotechnical and Underground Engineering of Ministry of EducationTongji UniversityShanghai 200092China Centre for Offshore Research and Engineering Department of Civil and Environmental EngineeringNational University of Singapore119077Singapore Land Transport Authority 219428Singapore

Ground losses due to tunneling would induce settlement of nearby raft *** study the change in behavior of the raft foundations over time due to tunnel excavation in soft clay,a series of centrifuge model tests were *** results reveal that the raft stiffness has a significant influence on the development of the gap between the raft and the *** width of the gap beneath the flexible foundation would increase over time,leading to a further increase in tensile strain after excavation,whereas the gap for raft foundations with a large stiffness would reduce with time,causing a gradual decrease in tensile *** modification factor(MF)design approach is also evaluated with the test results and demonstrates that the MF design approach would underestimate the tensile strain of the flexible raft and provide a relatively conservative prediction for larger stiffnesses.

关键词： Tunnelling Raft Clay Deflection ratio Centrifuge test

More Polyurethane in Thermal Insulation Materials for Buildings

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China Chemical Reporter 2010年第3期21卷 25-25页

作者： huang maosong

According to experts from the China RealEstate and Housing Research Association,the new floor area added each year in Chinais 50% of the world’s total,and China’sconstruction sector consumes 40% of thecountry’s total energy *** of thermal insulation in so muchnew building construction,walls inparticular,is one of the major problems

关键词： sector insulation today floor hardly steam walls t

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复杂应力状态下岩土体的非共轴塑性流动理论

岩石力学与工程学报 2006年第6期25卷 1259-1264页

作者：钱建固黄茂松中国科学院岩土力学重点实验室湖北武汉430071 同济大学地下建筑与工程系上海200092

由于传统的弹塑性本构模型是基于二维或三维的共轴应力空间和正交流动法则得到的,从而隐含了应力主方向和塑性应变率主方向共轴的局限性,由此引入非共轴塑性流动理论描述岩土体的本构特性。基于三维共轴应力空间定义多维应力状态下的非... 详细信息

由于传统的弹塑性本构模型是基于二维或三维的共轴应力空间和正交流动法则得到的,从而隐含了应力主方向和塑性应变率主方向共轴的局限性,由此引入非共轴塑性流动理论描述岩土体的本构特性。基于三维共轴应力空间定义多维应力状态下的非共轴应变率,进而建立非共轴本构理论框架。理论分析表明,***和***早期定义的非共轴塑性应变率是基于二维共轴应力空间得到的,由于忽略第三应力不变量的影响,在多维应力空间并不能保证其非共轴性。应力探测试验表明,在多维应力空间伴随着主应力的旋转将产生非共轴塑性应变,而在真三维应力状态下没有非共轴塑性应变产生,这与大量试验观察到的岩土体本构现象是一致的。

关键词：岩土力学共轴非共轴多维应力空间应力探测试验

水平循环荷载下砂土中沉井加桩基础累积变形特性

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岩石力学与工程学报 2016年第6期35卷 1265-1272页

作者：张勋黄茂松同济大学地下建筑与工程系上海200092 同济大学岩土及地下工程教育部重点实验室上海200092

采用自主设计的水平循环加载装置进行模型试验,探讨单向、不完全对称及双向对称循环加载路径下沉井加桩复合基础及沉井基础的变形特征与位移预测模型。模型试验表明:在近一万次循环荷载作用下,基础的水平循环累积位移随循环次数的增大... 详细信息

采用自主设计的水平循环加载装置进行模型试验,探讨单向、不完全对称及双向对称循环加载路径下沉井加桩复合基础及沉井基础的变形特征与位移预测模型。模型试验表明:在近一万次循环荷载作用下,基础的水平循环累积位移随循环次数的增大先增大后逐渐趋于稳定,呈两阶段变化特征,并且其大小受循环加载路径的影响较大,同时,与沉井基础相比,沉井加桩复合基础显著提高了基础抵抗水平循环变形的能力。最后,在对模型试验结果回归分析的基础上建立水平循环累积位移预测模型,并且其能较好地对不同循环加载路径下的基础变形进行预测。

关键词：土力学模型试验沉井加桩复合基础沉井基础水平循环加载砂土

基于饱和土总应力强度指标的非饱和土强度理论及其应用

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岩石力学与工程学报 2009年第3期28卷 635-640页

作者：马少坤黄茂松范秋雁广西大学广西南宁530004 同济大学地下建筑与工程系上海200092 同济大学岩土及地下工程教育部重点实验室上海200092

实际工程中求解和测定吸力比较困难,特别在不排水条件下,吸力并非常量,从而难以确定。而饱和度相对容易确定,选择饱和度代替吸力,建立关于饱和度的非饱和土的抗剪强度公式有着重要的实用价值。提出不排水(等含水量)条件下的基于饱和土... 详细信息

实际工程中求解和测定吸力比较困难,特别在不排水条件下,吸力并非常量,从而难以确定。而饱和度相对容易确定,选择饱和度代替吸力,建立关于饱和度的非饱和土的抗剪强度公式有着重要的实用价值。提出不排水(等含水量)条件下的基于饱和土总应力强度指标的抗剪强度公式,克服了以往相关模型只适合于较小范围的缺陷,能够实现从非饱和土状态到饱和状态的平稳过渡,同时更能反映土体的工程特性;结合非饱和土的土水特征曲线试验及常含水量三轴剪切试验成果,确定适用于云南红黏土的相关拟合参数;将所得抗剪强度公式应用于地基承载力分析中,得到地基承载力随饱和度的减少接近线性增加的结论。

关键词：土力学地基极限承载力非饱和土抗剪强度刚性基础

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考虑粗粒土应变软化特性和剪胀性的本构模型

同济大学学报（自然科学版） 2009年第6期37卷 727-732页

作者：孙海忠黄茂松同济大学岩土及地下工程教育部重点实验室上海200092 同济大学地下建筑与工程系上海200092

在传统细粒土本构模型的基础上进行了改进,建立了一个能较好地描述粗粒土应变软化特性和剪胀性的弹塑性本构模型.该模型采用双屈服面形式,克服了单屈服面模型存在的一些不足,可同时反映剪切变形和压缩变形机理.模型在应变软化特性描述方... 详细信息

在传统细粒土本构模型的基础上进行了改进,建立了一个能较好地描述粗粒土应变软化特性和剪胀性的弹塑性本构模型.该模型采用双屈服面形式,克服了单屈服面模型存在的一些不足,可同时反映剪切变形和压缩变形机理.模型在应变软化特性描述方面,提出了一个利用残余状态应力比和峰值应力比的应变软化公式,较为合理地反映了粗粒土的应变软化现象.在剪胀性描述方面,考虑了状态转换应力比与初始有效围压的相关性.数值模拟结果与试验结果较为接近,表明该模型描述粗粒土在低围压和相对中高围压下的应变软化特性和剪胀性方面具有一定的优越性.

关键词：粗粒土剪胀性应变软化本构模型

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隧道开挖条件下被动群桩遮拦效应分析

土木工程学报 2007年第6期40卷 69-74页

作者：黄茂松李早杨超同济大学上海200092

隧道开挖不可避免地会引起周围土体位移,从而导致临近建筑物桩基础产生附加变形和内力,降低桩基承载力,引起上部结构失稳甚至破坏。如何分析隧道开挖对邻近群桩的影响成为岩土工程界所关心的问题,为此作者提出隧道开挖对群桩影响的两阶... 详细信息

隧道开挖不可避免地会引起周围土体位移,从而导致临近建筑物桩基础产生附加变形和内力,降低桩基承载力,引起上部结构失稳甚至破坏。如何分析隧道开挖对邻近群桩的影响成为岩土工程界所关心的问题,为此作者提出隧道开挖对群桩影响的两阶段分析方法:第一阶段采用Loganathan等(1998)提出的解析解计算隧道开挖引起的土体自由位移场;第二阶段基于Winkler地基模型将土体自由位移施加于桩分析桩基的力学反应,同时考虑桩基的遮拦效应分析隧道开挖对群桩的影响。采用三维整体数值分析方法分析隧道开挖对临近群桩的影响,并通过对比验证了简化解析方法的合理性,在此基础上分析隧道开挖条件下被动群桩的遮拦效应,分析表明:(1)群桩遮拦效应随桩间距增大而减小;(2)遮拦效应对前排桩影响小于对后排桩的影响,尤其是轴力;(3)遮拦效应对位移的影响远小于对内力的影响,其中对水平位移的影响很小,可以忽略不计。

关键词：两阶段分析法数值分析被动群桩遮拦效应

Macro-micromechanical approaches for non-coaxiality of coarse grained soils

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Science China(Technological Sciences) 2011年第S1期54卷 147-153页

作者： QIAN JianGu 1,2,huang maosong 1,2 & SUN HaiZhong 1,2 1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China 2 Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai China Department of Geotechnical Engineering Tongji University Shanghai China

For coarse grained soils,their principal stress directions may change when the water level of embankment dam varies *** this loading case,the principal directions of stress and strain rate will become *** an effort to model non-coaxial behavior,a modified three-dimensional non-coaxial model is developed in the context of vertex yield(tangent plasticity) *** Element Method(PFC) incorporating user-defined interparticle contact models is also employed to gain an insight into microscopic mechanism of *** analysis focuses on non-coaxial behaviors under simple shear *** has been shown that the proposed non-coaxial model gives good predictions for non-coaxiality with reference to microscopic observations while the classical coaxial model fails to simulate the non-coaxial *** general,non-coaxiality as a result of the rotation of principal stress,is large at a small shear strain,and inclined to become negligible with increasing shear *** coarse grained soils,their non-coaxiality tends to largely depend on the initial normal pressure,where a larger degree of non-coaxiality can be observed at a higher pressure.

关键词： coarse grained soils non-coaxiality particle flow code simple shear