主动围压作用下混凝土-花岗岩组合体抗压力学特性与强度预测模型研究  

Compressive mechanical properties and strength prediction model of concrete-granite combined body under active confining pressure

作　　者：高欢 翟越[1,2] 汪铁楠 李宇白 王铭 李艳[1,2] GAO Huan;ZHAI Yue;WANG Tie-nan;LI Yu-bai;WANG Ming;LI Yan(School of Geological Engineering and Geomatics,Chang'an University,Xi'an,Shaanxi 710064,China;Key Laboratory of Western China's Mineral Resources and Geological Engineering of Ministry of Education,ChanganUniversity,Xi'an,Shaanxi 710064,China)

机构地区：[1]长安大学地质工程与测绘学院,陕西西安710064 [2]长安大学西部矿产资源与地质工程教育部重点实验室,陕西西安710064

出　　处：《岩土力学》2022年第11期2983-2992,3046,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.41772277,No.41941019);陕西省自然科学基础研究项目(No.2020JQ-373)。

摘　　要：混凝土-花岗岩组合体属于工程中典型的二元材料,在三轴条件下表现出与单体不同的力学响应特性。对混凝土单体(concrete monomer,简称CM)、花岗岩单体(granite monomer,简称GM)、混凝土-花岗岩组合体(concrete-granite combined body,简称CGCB)进行不同围压下的准静态压缩试验,通过扫描电子显微镜(scanning electron microscope,简称SEM)观察CGCB破坏后断口和界面的微观结构,并利用RFPA模拟CGCB的破坏过程,揭示组合体试件的整体裂纹扩展和破坏机制。最后基于Mohr-Coulomb强度准则建立了组合体三轴抗压强度预测模型。结果表明:组合体的单(三)轴抗压强度与材料尺寸效应和界面约束效应有关;随围压增大,组合体破坏状态由单轴的“Y”型劈裂破坏转变为混凝土组分剪切破坏;数值模拟结果表明,不同围压条件下远离界面的混凝土和界面近区的花岗岩依次发生损伤,逐渐形成贯通剪切裂纹,导致花岗岩组分发生劈裂破坏;所构建的强度预测模型能和试验结果、数值模拟很好地对应,表明了模型的准确性。研究结果可为深部地下工程结构的开挖和支护提供科学依据。The concrete-granite combined body is a typical binary material in engineering, with mechanical response properties that differ from monomer under triaxial circumstances. Concrete monomer(CM), granite monomer(GM), and concrete-granite combination body(CGCB) were subjected to quasi-static compression tests under various confining pressures. To reveal the overall crack propagation and failure mechanism of the composite specimens, SEM was used to study the fracture and interface microstructure of CGCB, and RFPA was employed to simulate the failure process of CGCB. Finally, based on the Mohr-Coulomb strength criterion, a prediction model for composite triaxial compressive strength was developed. The results show that the uniaxial(triaxial) compressive strength of CGCB is affected by the material size effect and the interface constraint effect, and the failure condition of the combined body shifts from uniaxial "Y" splitting failure to shear failure of the concrete component when confining pressure is increased. Under various confining pressures, the concrete away from the contact and the granite near the interface are damaged in turn, and shear fractures occur progressively, resulting in the splitting failure of granite components, according to the numerical simulation findings. The strength prediction model can match experimental data and numerical simulations effectively,demonstrating the accuracy of the model. The findings of the study might serve as a scientific foundation for the excavation and support of deep subterranean engineering constructions.

关 键 词：混凝土-岩石组合体 抗压强度模型 数值模拟 围压 破坏特征 

分 类 号：TU443[建筑科学—岩土工程]