杨婷婷, 杨永森, 邱流潮. 2018: 基于物质点法的土体流动大变形过程数值模拟. 工程地质学报, 26(6): 1463-1472. DOI: 10.13544/j.cnki.jeg.2017-453
    引用本文: 杨婷婷, 杨永森, 邱流潮. 2018: 基于物质点法的土体流动大变形过程数值模拟. 工程地质学报, 26(6): 1463-1472. DOI: 10.13544/j.cnki.jeg.2017-453
    YANG Tingting, YANG Yongsen, QIU Liuchao. 2018: MPM BASED NUMERICAL SIMULATION OF LARGE DEFORMATION PROCESS OF SOIL FLOW. JOURNAL OF ENGINEERING GEOLOGY, 26(6): 1463-1472. DOI: 10.13544/j.cnki.jeg.2017-453
    Citation: YANG Tingting, YANG Yongsen, QIU Liuchao. 2018: MPM BASED NUMERICAL SIMULATION OF LARGE DEFORMATION PROCESS OF SOIL FLOW. JOURNAL OF ENGINEERING GEOLOGY, 26(6): 1463-1472. DOI: 10.13544/j.cnki.jeg.2017-453

    基于物质点法的土体流动大变形过程数值模拟

    MPM BASED NUMERICAL SIMULATION OF LARGE DEFORMATION PROCESS OF SOIL FLOW

    • 摘要: 土体滑坡作为一种自然地质灾害,受自然因素和人类活动的影响在我国时有发生,给周围居民的生命和财产安全带来了很大威胁,日益受到人们的广泛关注。滑坡防治也逐渐成为工程研究的热点之一。土体本质上是一种具有复杂组成结构的颗粒材料堆积体,通过对颗粒流动的模拟可以深入理解自然界中的土体流动现象,如滑坡、泥石流等,进而预测灾害破坏范围及改进相应工程防护措施。但由于土体流动是一个涉及大变形及大位移的复杂流动过程,传统的基于网格的有限元法(FEM)由于网格畸变,并不适合这类问题的研究。本文采用物质点法(MPM)模拟土体流动大变形问题。作为一种源于particle-in-cell(PIC)法的无网格法,兼具欧拉法和拉格朗日法的优点,因而,物质点法在处理大变形问题上具有独特的优势。目前,国内外利用物质点法模拟边坡滑动问题已有不少研究,但对相关参数进行敏感性分析的较少。本文基于物质点法模拟了黏性土体及无黏性土体流动大变形问题,并进行了参数敏感性分析,包括土体材料的内摩擦角、黏聚力、高宽比、底面坡度对土体滑动距离的影响规律。本文计算中采用Drucker-Prager(DP)弹塑性本构模型描述土的非线性特性。研究结果表明:(1)基于物质点法得到的土体的流动形态、滑动距离以及自然休止角等数值模拟结果均与文献中的实验结果基本吻合,验证了物质点法模拟土体大变形力学行为的精度及有效性;(2)随着内摩擦角、黏聚力的增大,滑动距离相应减小;(3)坡度对边坡稳定的影响是显著的,随着底面坡度的增大,滑动距离相应增大;(4)当土柱高宽比较小时,与滑动距离呈线性增长关系。其中,内摩擦角和黏聚力反映了土体的抗剪切性能,因此通过工程措施提高土体的抗剪能力可以降低土体滑坡带来的危害。研究结果为探索土体滑动破坏规律,降低滑动破坏范围提供了可靠的参考。

       

      Abstract: As a natural geologic disaster, soil landslide is affected by natural factors and human activities. It brings a great threat to the safety of the surrounding residents' life and property, attracting more worries from people. Landslide prevention and control are also one of the hot spots in engineering research. Soil is essentially a kind of deposits consists of granular material with complicated composition and structure. By means of numerical simulation of granular material flows, we can well understand the phenomena of soil flows in the nature, such as landslide and debris flows. It is therefore possible to predict the landslide hazard zone and to improve the design of engineering protection measurements. However, the finite element method(FEM) is not suitable for simulating soil flow with large deformation and large displacement due to the finite element method is sensitive to mesh distortion. In this paper, we simulate the soil flows using the material point method(MPM). MPM is a mesh-free method and originating from the particle-in-cell(PIC)method. It combines the Eulerian description and Lagrangian description and has distinct advantages in solving the large deformation and large displacement problem. Currently, there have been many studies on the simulation of slope sliding using MPM, but less attentions has paid to sensitivity analysis on relevant parameters. In this paper, the large deformations of the cohesive soil and the non-cohesive soil slopes due to gravity are numerically investigated with MPM.The influence of the internal friction angle, the cohesive force, the aspect ratio and bottom surface gradient on the landslide run-out are analysed. In this MPM simulation, the elasto-palstic constitutive models based on the Drucker-Prager(DP)yield criterion is used for modeling nonlinear characters of soil flows. The Drucker-Prager yield criterion is a pressure-dependent model for determining whether a material has failed or undergone plastic yielding. The yielding surface of the Drucker-Prager criterion may be considered depending on the internal friction angle of the material and its cohesion. The simulated results show the following featurs. (a) There are well agreements in the flow pattern, the sliding distance and natural angle of repose between the simulated results and the corresponding experimental results, which validates the ability of MPM to modeling soil flows. (b) The sliding distance decreases with the increase of the internal friction angle and cohesive force. (c) The steepness of the soil slope has significant influence on its stability. The sliding distance increases with the increase of the steepness of the soil slope. (d) For a comparatively small aspect ratio, the sliding distance increases linearly with aspect ratio. It is noteworthy that the internal friction angle and cohesive force of soil reflect its shear resistance. Therefore, the damage due to landslide can be reduced by improving the shear resistance of soil through engineering measurements. The results of the simulation provide a reliable reference to explore the law of the soil sliding hazardous behavior and reduce the sliding damage range.

       

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