填土应力路径下珊瑚砂幂律应力-应变模型的适用性研究  

Applicability of power-law stress-strain model for coral sand under earth fill stress path

作　　者：张季如[1] 郑颜军 彭伟珂 王磊 陈敬鑫 ZHANG Ji-ru;ZHENG Yan-jun;PENG Wei-ke;WANG Lei;CHEN Jing-xin(School of Civil Engineering and Architecture,Wuhan University of Technology,Wuhan,Hubei 430070,China)

机构地区：[1]武汉理工大学土木工程与建筑学院,湖北武汉430070

出　　处：《岩土力学》2023年第5期1309-1318,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.42172295)。

摘　　要：岛礁工程建设常用珊瑚砂吹填地基或作为土工构筑物的填料。珊瑚砂在填筑期的应力路径具有静止土压力系数K_(0)固结和等应力比路径的特点,为了准确预估填筑期的填土变形量,需要建立能够反映填土应力路径影响的变形计算模型。根据广义虎克定律,建立了幂律形式的非线性弹性模型来描述土体的应力-应变关系,提出了变形参数的表达式。对珊瑚砂开展了K_(0)固结试验和等应力比路径下的排水三轴压缩试验,分析了珊瑚砂的应力-应变曲线和颗粒破碎状况,研究了幂律应力-应变模型的适用性,并将模型计算结果与试验曲线进行了对比。结果表明:填土路径下的应力-应变曲线具有幂函数曲线形式,可以用幂律非线性弹性模型来描述。模型的切线模量和切线泊松比均可以表示为轴向有效应力的函数,并通过与主应力比或系数K_(0)相关的参数得到表达。等应力比路径下的切线泊松比和切线模量随着轴向有效应力的增加而增大。在相同的轴向有效应力条件下,主应力比越大,切线模量越大,切线泊松比越小。随着轴向有效应力的增加,K_(0)固结珊瑚砂的静止土压力系数和切线泊松比减小,切线模量增大。在试验应力范围内,填土路径下珊瑚砂的颗粒破碎量都很小,对应力-应变特性的影响不大。幂律模型合理地预测了一定主应力比值范围内等应力比路径下珊瑚砂的应力-应变曲线,并能够考虑应力路径对应力-应变关系的影响。Coral sands are commonly used in hydraulic fill foundations and as subgrade fill in the construction of islands and reefs.The stress paths followed by soil consolidation or filled subgrade are characterized by K_(0) consolidation or constant stress ratio path.It is necessary to develop a computational model that reflects the effect of stress path on deformation in order to accurately estimate soil deformation during the filling process.Based on the generalized Hooke's law,a nonlinear elastic model in the form of a power function is proposed to describe the stress-strain curve of coral sand,and the functional expression is given.A series of K_(0)consolidation tests and drained triaxial compression tests with a constant stress ratio path is conducted on the coral sand to investigate the stress-strain curves and the behavior of particle breakage.The applicability of the power-law stress-strain model for the coral sand under the earth fill stress path is investigated,and the calculated results of the model are compared with the test curves.The results show that the stress-strain curves under both K_(0) consolidation and constant stress ratio paths conform to the form of power-law curves and can be described by a power-law nonlinear elastic model.The tangent modulus and tangent Poisson's ratio of this model can be expressed as a function of axial effective stress and can be determined by parameters related to the principal stress ratio or K_(0)coefficient.Under a constant stress ratio path,the tangent Poisson's ratio and tangent modulus increase with the increase of the axial effective stress.For the same axial effective stress condition,a large principal stress ratio corresponds to a large tangent modulus and a small tangent Poisson's ratio.With the increase of the axial effective stress under the condition of K_(0) consolidation,the coefficient of earth pressure at rest and tangent Poisson's ratio decrease,while the tangent modulus increases.Under the stress paths of K_(0)consolidation and constant stress ratio,the

关 键 词：幂律应力-应变模型 应力路径三轴试验 珊瑚砂 等应力比路径 K0固结 

分 类 号：TU411[建筑科学—岩土工程]