堆积碎石土离散元细观参数—宏观力学参数相关性研究
发布时间：2018-11-09 12:41
【摘要】：堆积碎石土是土石混合体的一种,由强度较高的碎石和强度较低的土体,经复杂成因形成的土与块石的二重介质混合体。由堆积碎石土组成的坡体和滑坡广泛存在于我国各地(尤其是南方地区),容易引起工程滑坡或坍塌,带来巨大的经济损失和人员伤亡。国内外学者对土石混合体力学特性和变形机制的研究越来越多,早期以室内试验或室外原位试验研究手段为主。随着离散元软件的出现,为土石混合体不连续介质的数值模拟提供了可靠的平台,并且数值模拟试验花费相对较低,精确性又能够得到保证,越来越受到研究学者的青睐。但是,在运用离散元软件进行数值模拟之前必须找到反映材料宏观特性的细观参数。由于细观参数与材料自身的宏观力学参数间存在诸多难以控制因素,并且这些因素之间非线性极为显著,获得两者之间关系极其不容易,则细观参数标定一般采用试凑法获得,并且此过程需耗费大量的时间和精力。为此,本文以昭山地区的堆积碎石土室内试验为基础,运用PFC3D离散元软件生成含有不同形状碎石块的1:1堆积碎石土数值模型,通过标定得到相应地细观参数(相对误差控制在10%以内)。改变细观参数,定量探讨其和宏观力学参数(粘聚力和内摩擦角)之间的关系,得到细观参数与宏观力学参数间的的细-宏观参数关系式,并对其可靠性进行了验证。主要结论如下:(1)粘聚力与接触粘结力、颗粒摩擦系数关系为线性正相关;同时受粘结力比值M=/c c??的影响,当M1时,粘聚力随着M的增加而线性增加;M≥4时,粘聚力基本保持不变;(2)内摩擦角与颗粒摩擦系数呈对数关系,与接触粘结力呈抛物线关系;(3)得到了细观参数-宏观力学参数的联合关系式,通过了可靠性验证。细观参数-宏观力学参数关系式是在含水率为7%的室内试验结果基础上得出的,将关系式运用到含水率为9%、11%和13%的室内试验结果进行标定验证:依据含水率为9%和11%、13%室内试验得到的c、?值,运用细-宏观参数关系式计算得到细观参数,经验证其数值-室内试验结果相对误差在10%以内,说明通过细-宏观力学关系式得到的细观参数符合精度要求,关系式可靠。为后续土石混合体数值试验研究进行细观参数标定工作提供了参考依据。
[Abstract]:The aggregate gravel soil is a kind of mixed soil and rock, which is composed of high strength gravel and low strength soil, and is formed by complex genesis of mixed soil and rock duplex medium. The slope body and landslide composed of accumulated gravel soil are widely found in all parts of our country (especially in southern China), which can easily cause engineering landslide or collapse, and bring huge economic losses and casualties. There are more and more researches on the mechanical properties and deformation mechanism of soil-rock mixture at home and abroad, and the early research methods are indoor test or outdoor in-situ test. With the emergence of discrete element software, it provides a reliable platform for the numerical simulation of soil and rock mixed discontinuous medium, and the cost of numerical simulation experiment is relatively low, and the accuracy can be guaranteed, which is more and more popular among researchers. However, the meso-parameters reflecting the macroscopic properties of materials must be found before the numerical simulation is carried out by using discrete element software. Because there are many uncontrollable factors between the meso-parameters and the macroscopic mechanical parameters of the material itself, and the nonlinearity between these factors is very significant, it is not easy to obtain the relationship between them, so the calibration of the meso-parameters is usually obtained by means of trial and error. And the process takes a lot of time and effort. In this paper, based on the laboratory test of packed gravel soil in Zhaoshan area, the numerical model of 1:1 gravel soil with different shapes is generated by using PFC3D discrete element software. The corresponding mesoscopic parameters are obtained by calibration (the relative error is controlled within 10%). The relationship between meso-parameters and macroscopic mechanical parameters (cohesion and angle of internal friction) is discussed quantitatively. The relationship between meso-parameters and macro-mechanical parameters is obtained, and its reliability is verified. The main conclusions are as follows: (1) the relationship between cohesive force and contact adhesion, particle friction coefficient is linear positive correlation, and the adhesion ratio M / c? When M1, the cohesive force increases linearly with the increase of M, when M 鈮，
本文编号：2320443
[Abstract]:The aggregate gravel soil is a kind of mixed soil and rock, which is composed of high strength gravel and low strength soil, and is formed by complex genesis of mixed soil and rock duplex medium. The slope body and landslide composed of accumulated gravel soil are widely found in all parts of our country (especially in southern China), which can easily cause engineering landslide or collapse, and bring huge economic losses and casualties. There are more and more researches on the mechanical properties and deformation mechanism of soil-rock mixture at home and abroad, and the early research methods are indoor test or outdoor in-situ test. With the emergence of discrete element software, it provides a reliable platform for the numerical simulation of soil and rock mixed discontinuous medium, and the cost of numerical simulation experiment is relatively low, and the accuracy can be guaranteed, which is more and more popular among researchers. However, the meso-parameters reflecting the macroscopic properties of materials must be found before the numerical simulation is carried out by using discrete element software. Because there are many uncontrollable factors between the meso-parameters and the macroscopic mechanical parameters of the material itself, and the nonlinearity between these factors is very significant, it is not easy to obtain the relationship between them, so the calibration of the meso-parameters is usually obtained by means of trial and error. And the process takes a lot of time and effort. In this paper, based on the laboratory test of packed gravel soil in Zhaoshan area, the numerical model of 1:1 gravel soil with different shapes is generated by using PFC3D discrete element software. The corresponding mesoscopic parameters are obtained by calibration (the relative error is controlled within 10%). The relationship between meso-parameters and macroscopic mechanical parameters (cohesion and angle of internal friction) is discussed quantitatively. The relationship between meso-parameters and macro-mechanical parameters is obtained, and its reliability is verified. The main conclusions are as follows: (1) the relationship between cohesive force and contact adhesion, particle friction coefficient is linear positive correlation, and the adhesion ratio M / c? When M1, the cohesive force increases linearly with the increase of M, when M 鈮，
本文编号：2320443
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