基于南水模型的钙质砂应力-应变关系模拟  

Simulation of carbonate sand with triaxial tests data based on modified model of South water double yield surface

作　　者：谷建晓 杨钧岩 王勇[1] 吕海波[1,2] GU Jian-xiao;YANG Jun-yan;WANG Yong;LÜHai-bo(Guangxi Key Laboratory of Rock and Soil Mechanics and Engineering,Guilin University of Technology,Guilin,Guangxi 541004,China;Architectural Engineering College,Hezhou College,Hezhou,Guangxi 542899,China)

机构地区：[1]桂林理工大学广西岩土力学与工程重点实验室,广西桂林541004 [2]贺州学院建筑工程学院,广西贺州542899

出　　处：《岩土力学》2019年第12期4597-4606,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金（No.51169005,No.41272358）;广西自然科学基金（No.2018JJD160019）~~

摘　　要：钙质砂是一种海洋生物成因的特殊岩土材料,具有颗粒性状不规则、易破碎的特点,表现出与石英砂不同的力学性质。为模拟钙质砂在不同应力水平下的应力-应变关系,首先分析南水模型的不足:即无法描述应力不变情况下应变无限增长的特点和不能描述钙质砂的剪胀性;然后通过在切线模量中引入应力比与峰值应力比的比值,合理考虑了颗粒破碎的影响;提出了切线模量和切线体积比与应力比间的函数关系式,使得改进后的模型能较好地描述应变-体变关系。同时,将孔隙压力系数引入到孔隙压力表达式中,较好地模拟了三轴不排水剪切试验结果。与现有的模型相比,改进后的模型表达式简单易懂,参数获取更为方便。Carbonate sand, a geomaterial with special structural and mechanical properties, is the main material of the South China Sea Island Reef blow-fill project. A series of drained triaxial tests was carried out on carbonate sand that had previously been extensively researched. This paper presents a modified model referred to as the Shen Zhujiang’s elastoplastic model that is capable of predicting the experimental data and simulating the stress-strain behaviour of carbonate sand over a wide range of confining pressures and regions. A functional relationship between the tangent modulus and the ratio of tangential volume to the stress ratio of carbonate sand is proposed. These functional relationships enable the model to describe the characteristic transitions from contractive to dilative shear response of carbonate sands as the stress increases under low confining pressure. Meanwhile, predictions based on the modified models are obtained and compared with the experimental data of the carbonate sand. It is found that the characteristic dilatancy and contraction of carbonate sand, as well as the stress-strain softening curve can be reasonably described compared with the drained triaxial tests data to illustrate the modified model capability for describing the shear behaviour of carbonate sands. For the un-drained triaxial tests, the pore pressure coefficient was introduced into the expression of pore pressure, and the results show that the data is well simulated. Compared with the existing Sun Jizhu’s elastoplastic model, the proposed model expression is easy to understand and the parameters can be obtained easily.

关 键 词：钙质砂 南水模型 切线模量 孔隙压力 应力-应变关系 

分 类 号：TU452[建筑科学—岩土工程]