| 卸荷条件下花岗岩力学特性分析 |
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| 引用本文： | 金爱兵,刘佳伟,赵怡晴,王本鑫,孙浩,魏余栋.卸荷条件下花岗岩力学特性分析[J].岩土力学,2019,40(Z1):459-467. |
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| 作者姓名： | 金爱兵 刘佳伟 赵怡晴 王本鑫 孙浩 魏余栋 |
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| 作者单位： | 1. 北京科技大学 土木与资源工程学院，北京 100083；2. 北京科技大学 金属矿山高效开采与安全教育部重点实验室，北京 100083 |
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| 基金项目： | 国家自然科学基金项目（No.51674015）；国家重点实验室2017年开放基金课题（No.SHJT-17-42.1）。 |
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| 摘 要： | 岩体工程中的开挖会不可避免地与岩体卸荷相关联。以花岗岩为试验材料，通过室内试验研究线性卸荷条件下花岗岩的破裂特征，其表现为径向快速扩容及塑性特征的增强。在室内试验的基础上，基于PFC(particle flow code)颗粒流程序，采用平节理模型FJM(flat joint model)模拟花岗岩卸荷条件下的力学特性。鉴于实际工程中岩体的开挖大部分为非线性卸荷，文中运用一种新的“应力/时步”卸荷方式，能够方便地完成非线性卸荷的模拟。数值模拟结果表明，在加轴压卸围压的条件下花岗岩试样损伤严重，承载能力急剧下降，无残余强度，随着初始围压的增加，破坏形式由劈裂过渡为剪切破坏，卸荷速度越快，裂纹扩展越慢。研究结果可为岩石卸荷条件下的力学行为分析以及实际工程提供借鉴。
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| 关 键 词： | 花岗岩 卸荷岩体 力学特性 数值模拟 |
| 收稿时间： | 2018-10-15 |
Mechanical characteristics analysis of granite under unloading conditions |
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| JIN Ai-bing,LIU Jia-we,ZHAO Yi-qing,WANG Ben-xin,SUN Hao,WEI Yu-dong.Mechanical characteristics analysis of granite under unloading conditions[J].Rock and Soil Mechanics,2019,40(Z1):459-467. |
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| Authors: | JIN Ai-bing LIU Jia-we ZHAO Yi-qing WANG Ben-xin SUN Hao WEI Yu-dong |
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| Institution: | 1. School of Civil and Resources Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine, University of Science and Technology Beijing, Beijing 100083, China |
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| Abstract: | Excavation in the rock mass engineering is inevitably associated with the rock mass unloading. In this paper, the granite is selected as the test material, the rupture characteristics of the granite under linear unloading conditions are studied experimentally. The rapid dilation in the radial direction and the enhancement of the plasticity are found. Furthermore, the FJM (flat joint model) in the PFC (particle flow code), is applied to simulate the mechanical properties of the granite under unloading conditions. A new “stress/time step” unloading method, which can easily execute the simulation of the nonlinear unloading behavior, is used considering that the excavation of the rock mass in the practical engineering is mostly characterized as the nonlinear unloading behavior. Numerical simulation results show that the granite is seriously damaged when the axial pressure is increased and the confining pressure is unloaded. The load capacity was decreased sharply and no residual strength is found. As the initial confining pressure increases, the failure mode is transformed from the splitting to the shear failure. The faster the unloading speed, the slower the crack propagation is found. The research results can provide the reference for the study of the mechanical behavior and the practical engineering under unloading conditions. |
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| Keywords: | granite unloading rock mass mechanical characteristic numerical simulation |
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