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工程科学与技术:2021,53(4):63-72
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基于DEM-CFD耦合方法的煤系土边坡失稳机理宏细观分析
(1.南昌工程学院 江西省水利土木工程基础设施安全重点实验室,江西 南昌 330099;2.南昌工程学院 土木与建筑工程学院,江西 南昌 330099)
Macro and Micro Analysis on Instability Mechanism of Coal Measure Soil Slope Based on DEM-CFD Coupling Method
(1.Jiangxi Provincial Key Lab. of Hydraulic & Civil Eng. Infrastructure Security, Nanchang Inst. of Technol., Nanchang 330099, China;2.School of Civil and Architectural Eng., Nanchang Inst. of Technol., Nanchang 330099, China)
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投稿时间:2020-08-10    修订日期:2020-11-19
中文摘要: 边坡的宏观力学特性是由组成土体颗粒的细观参数及其运动决定的,基于连续介质模型的有限元方法虽然能够在宏观层面上基本等效地得到边坡土体的应力变形特性,但难以反映边坡体在微细观尺度上的变形失稳机理,存在明显的局限性。将离散元方法(discrete element method,DEM)与计算流体动力学方法(computational fluid dynamic,CFD)进行耦合,建立了煤系土边坡3维DEM-CFD流固耦合细观作用计算模型,对降雨作用下煤系土边坡失稳破坏的细观机理进行分析。结果表明,采用DEM-CFD流固耦合方法模拟的煤系土边坡破坏形式主要是雨水冲刷,边坡滑动面预测为近似的直线段,这与室外模型试验边坡雨水冲刷的范围非常接近,验证了该数值方法的适应性。边坡土体颗粒的力链、配位数以及孔隙率等细观参数,在降雨过程中都会随之发生变化,如坡顶颗粒的孔隙率由初始状态的0.35变化至失稳状态的0.80,这些细观参数的变化与边坡土体的宏观力学表现直接关联。文中通过对颗粒细观参数变化分析,从细观角度解释了雨水作用下煤系土边坡的破坏演变规律。研究成果为该区域煤系土边坡的防护设计与施工提供理论依据,并从微细观角度更好地分析离散介质岩土工程的宏观力学规律提供了一种思路。
Abstract:The macro mechanical properties of slope are determined by the meso parameters of soil particles and their motion. Although the stress and deformation characteristics of slope at the macro level can basically be obtained by the finite element method based on continuum model, it is difficult to reveal the deformation and instability mechanism of slope in the micro scale, and there are obvious limitations. The three-dimensional DEM-CFD model of fluid solid interaction of coal measure soil slope was established by coupling DEM and CFD. The meso mechanism of coal measures soil slope failure under rainfall was analyzed. The results show that the failure mode of coal measure soil slope simulated by DEM-CFD is mainly of rain erosion, and the slope sliding surface is predicted to be of approximate straight-line section, which is very close to the range of rain erosion of slope in outdoor model test. This shows that the numerical method is suitable to analyze the stability of coal measure soil slope. Micro parameters such as force chain, coordination number and porosity of soil particles in slope will change during the rainfall. For example, the porosity of particles on the top of slope changed from 0.35 in initial state to 0.8 in unstable state. The change of these micro parameters is directly related to the macro mechanical performance of the slope soil. In this paper, the law of the failure evolution of the coal measure soil slope under the rainfall was explained through the analysis of the micro parameters change of the particles. The research results of this paper not only provides theoretical basis for the protection design and construction of the coal measure soil slope in this area, but also provides a new way of analyzing the macro mechanical laws in geotechnical engineering from the micro perspective.
文章编号:202000671     中图分类号:TU413.6    文献标志码:
基金项目:国家自然科学基金项目(52068053);江西省教育厅科技项目(GJJ161101);南昌市2017年优势科技创新团队项目(2017CXTD012);江西省交通运输厅科技项目(2020X0013)
作者简介:第一作者:张鸿(1972-),男,教授,博士.研究方向:岩土工程.E-mail:zhanghlion@163.com
引用文本:
张鸿,张榜,丰浩然,吴灿.基于DEM-CFD耦合方法的煤系土边坡失稳机理宏细观分析[J].工程科学与技术,2021,53(4):63-72.
ZHANG Hong,ZHANG Bang,FENG Haoran,WU Can.Macro and Micro Analysis on Instability Mechanism of Coal Measure Soil Slope Based on DEM-CFD Coupling Method[J].Advanced Engineering Sciences,2021,53(4):63-72.