饱和砂土的三剪弹塑性边界面模型研究(二)--模型验证及应用  

Approaches to the triple-shear elasto-plasticity bounding surface model for saturated sands(2)——verification sand applications

作　　者：胡小荣[1] 董肖龙 汪日堂 Hu Xiaorong;Dong Xiaolong;Wang Ritang(School of Civil Engineering and Archiecture,Nanchang University,330031,Nanchang,China)

机构地区：[1]南昌大学建筑工程学院,南昌330031

出　　处：《应用力学学报》2020年第3期1283-1292,I0026,I0027,共12页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(11362016,10862004)。

摘　　要：为验证所提饱和砂土三剪弹塑性边界面本构模型的适用性,取南昌地铁某车站进出口底板下的纯砂,掺入粒径小于0.075mm的江西红黏土颗粒,配制成含泥量分别为0%、5%、10%且密实度分别为25%、45%、70%的砂土样,通过常规三轴试验和循环动三轴试验确定模型参数,将试验数据与理论计算结果对比后发现两者具有较好的一致性,本构模型能较真实地反映饱和砂土样的变形、体变、孔隙水压力特性。其中,等量代换法和坐标平移法的数值计算结果相差不大,坐标平移法数值计算结果更接近试验结果。结果还表明:在单调荷载作用下,砂土的围压和含泥量越大,剪胀现象越不明显;砂土的密实度越大,剪胀现象越明显。在循环荷载作用下,砂土的围压和密实度越大,达到循环稳定时的轴向应变和孔隙水压力越小;轴向应力幅值、频率、含泥量越大,达到循环稳定时的轴向应变和孔隙水压力越大。另外,还将本构模型应用于砂土样的真三轴数值模拟。结果表明:单调加载时中间主应力影响系数b取值越大,应力峰值也越大;循环加载时侧向主应力σ2和σ3与竖向应变的关系均呈负相关性,侧向最小主应力s3、含泥量、循环应力幅值与孔隙水压力的关系呈正相关性。In order to verify the feasibility and accuracy of the constitutive model and the finite element formula proposed in the first part of the paper"Approaches to the triple-Shear elasto-plasticity bounding surface model for saturated sands(1)—model theory",pure sands were acquired from the floor under the entrance of a subway station in Nanchang and mixed with the Jiangxi red clay particles of sizes less than 0.075 mm to prepare the samples with clay contents of 0%,5%and 10%,and relative compactnesses of 25%,45%and 70%,respectively.The model parameters under monotonic and dynamic loading are determined by conventional tri-axial test sand dynamic tri-axial tests under the cyclic loading.Through comparison,it is found that the experimental data and numerical results are in good agreement.The constitutive model can accurately reflect the characteristics of the axial and bulk deformations and the pore water pressures for the saturated sand samples.Among them,the numerical results with the equivalent substitution method have less differences than with the coordinate translation method,which are closer to the tested results.Calibrations also show that the dilatancy is less obvious with more increases of the confining pressures and the mud contents.On the other hand,the higher compactness also means the more obvious dilatancy under the monotonic loading.Under the cyclic loading,the axial strains and the pore water pressures decrease with the increases of the confining pressure and compactness.Larger axial stresses,frequencies and mud contents reveal the greater axial strains and the pore water pressures when the cyclic stability is achieved.In spite of above,the constitutive model proposed in paper part one is also applied to the true tri-axial numerical simulations for the sand samples.Results under the monotonic loading show that the larger the intermediate principal stress influence coefficient b gives the larger stress peak for the sand samples.Under the cyclic loading,the lateral principal stressesσ2 andσ3 have ne

关 键 词：饱和砂土 常规三轴试验 循环动三轴试验 真三轴数值模拟 

分 类 号：TU432[建筑科学—岩土工程]