考虑块体内耦合作用及锚杆塑性效应的非连续变形分析方法

发布时间：2018-06-07 02:24

本文选题：非连续变形分析 + 地下洞室群　；参考：《山东大学》2014年博士论文

【摘要】：随着大型水利水电工程以及深部资源开发工程的飞速发展,岩石非连续大变形问题的理论与计算成为学术界研究的焦点。块体系统非连续变形分析(DDA)是近三十年来才发展起来的一种新的数值计算方法,它在满足弹性理论基本方程的条件下能够反映出岩体变形的不连续性,既具有离散元法可计算块体大位移的特点,又具有有限元理论基础的严密性,具有广泛的应用前景,是目前岩土工程分析中的研究热点之一。非连续变形分析方法由于发展的较晚,在工程应用方面有诸多的局限性。本文对非连续变形分析方法进行了改进,考虑了位移收敛准则和锚杆的塑性变形。然后建立了非连续变形分析方法与有限元方法的耦合程序,讨论了并行算法。最后结合四川巴底水电站项目对该方法进行了深入研究,主要研究了等效力学参数的确定和动态施工过程等。本文的主要工作概括如下： 1.对非连续变形分析方法进行了改进,加入了位移收敛判断准则。然后采用非连续变形分析方法对双裂隙岩块进行单轴和双轴压缩模拟试验,研究了裂隙角度和侧向应力大小对岩块特性的影响,得到了裂隙岩块在这两种加载试验中的破坏过程和应力—应变曲线,同时也得到了岩块中裂隙的起裂应力和岩块的峰值强度。在双轴压缩模拟试验中绘制了裂隙角度为45。岩块在不同侧向压力下的强度包络线,并根据包络线方程式确定参数的c、φ的取值,同时根据等效连续介质分析方法分析了某地下洞室的稳定性。随后,在程序中加入了锚杆的塑性变形力学模型,并采用改进后的程序模拟了劈裂试验中含裂隙试块的锚固效果,得到锚杆的塑性力学特性可以更好的描述锚杆的受力,更贴近工程实际情况。 2.应用有限元参数化设计语言APDL,开发了非连续变形分析方法程序与有限元程序图形用户界面的接口程序ANSYS2DDARF,可以生成BLAC文件,使前处理更加直观方便。同时,在线性位移模式下,推导了非连续变形分析程序和有限元程序耦合方法的总体平衡方程,并且详细推导了相应的的弹性子矩阵、惯性子矩阵、荷载子矩阵和接触子矩阵等。非连续变形分析方法与有限元方法耦合后,每个块体的自由度由网格节点的数量所确定,更加准确的描述了块体的变形。最后采用耦合分析方法分析了某地下洞室围岩的位移影响因素,得到侧压力系数、围岩破碎面粘聚力、内摩擦角、抗拉强度对围岩的位移影响较大,同时顶拱为支护的关键位置,为工程提供了参考。 3.考虑了非连续变形分析方法基于OpenMP的并行算法。首先提出了刚度矩阵并行组装策略,对非连续变形分析的刚度矩阵进行了并行化处理。然后对非连续变形分析的方程组计算采用改进的SSOR-PCG方法。最后通过算例表明改进后的并行算法可以使程序具有良好的加速比,明显的提高了模型的计算速度。 4.在非连续变形分析方法的实际工程应用中,以四川巴底水电站地下洞室群为研究背景,首先数值模拟中的力学参数考虑了岩体中节理的随机性和岩体力学参数的不确定性,通过现场实测数据和数值模拟的方法进行等效确定。然后研究了动态施工方法,突出了对开挖顺序、分步开挖、分步支护过程进行模拟计算分析,并给出相应的解决方法,使程序可以更加真实的反映实际施工过程。 5.将非连续变形分析方法与有限元方法的耦合问题,动态施工过程,基于OpenMP并行问题,锚杆的塑性变形力学模型和位移收敛准则使用C++语言在VC++平台中编制到计算程序中,使程序同时具备较好的分析块体变形的功能和工程应用的功能。
[Abstract]:With the rapid development of large water conservancy and hydropower projects and deep resource development projects, the theory and calculation of rock discontinuous large deformation have become the focus of academic research. The discontinuous deformation analysis (DDA) of block system is a new numerical method developed in the last thirty years. It is satisfied with the basic equations of elastic theory. Under the conditions, it can reflect the discontinuity of rock mass deformation, not only the discrete element method can calculate the large displacement of the block body, but also has the tightness of the finite element theory basis. It has a wide application prospect. It is one of the hot topics in the analysis of geotechnical engineering. The non continuous deformation analysis method is applied in engineering because of the late development. There are many limitations in the surface. In this paper, the method of discontinuous deformation analysis is improved, the displacement convergence criterion and the plastic deformation of the bolt are considered. Then the coupling program of the discontinuous deformation analysis method and the finite element method is established, and the parallel algorithm is discussed. Finally, the method is deeply studied in combination with the project of Sichuan Ba Di hydropower station. The determination of equivalent mechanical parameters and dynamic construction process are mainly studied. The main works in this paper are summarized as follows:
1. the discontinuous deformation analysis method was improved, and the criterion of displacement convergence was added. Then the discontinuous deformation analysis method was used to simulate the double fracture rock mass by single axis and biaxial compression simulation, and the influence of the fracture angle and the lateral stress size on the rock mass characteristics was studied, and the fractured rock block was obtained in the two loading tests. The fracture stress and the peak strength of the rock mass in the rock mass are also obtained by the failure process and the stress strain curve. In the biaxial compression simulation test, the strength envelope of the fracture angle of 45. rock under different lateral pressures is drawn, and the value of the parameters of C and phi is determined according to the equation of the envelope line, and the equivalent continuum is based on the equivalent continuum. The stability of a certain underground cavern is analyzed by the qualitative analysis method. Then, the mechanical model of the plastic deformation of the bolt is added to the program, and the anchorage effect of the fracture test block is simulated by the improved program. The plastic mechanical properties of the bolt can be obtained to describe the stress of the bolt better and close to the actual situation of the engineering.
2. using the finite element parameterized design language APDL, the interface program ANSYS2DDARF of the discontinuous deformation analysis program and the finite element program graphical user interface is developed. The BLAC file can be generated to make the preprocessing more intuitive and convenient. At the same time, the discontinuous deformation analysis program and the finite element program coupling side are derived under the linear displacement mode. The general equilibrium equation of the method and the corresponding elastic submatrix, inertia submatrix, load submatrix and contact submatrix are derived in detail. After coupling the discontinuous deformation analysis method with the finite element method, the degree of freedom of each block is determined by the number of grid nodes, and the deformation of the block is described more accurately. Finally, the coupling is used. The analysis method analyses the influence factors of the displacement of the surrounding rock of an underground cavern, and obtains the side pressure coefficient, the cohesive force of the broken wall of the surrounding rock, the internal friction angle and the tensile strength of the surrounding rock, and the top arch is the key position of the support, which provides the reference for the project.
3. the parallel algorithm based on OpenMP for discontinuous deformation analysis is considered. First, the parallel assembly strategy of stiffness matrix is proposed, and the stiffness matrix of discontinuous deformation analysis is parallelized. Then the improved SSOR-PCG method is used for the equation group calculation of discontinuous deformation analysis. Finally, the improved parallel calculation is shown by an example. The method can make the program have a good speedup, and obviously increase the computation speed of the model.
4. in the practical engineering application of the discontinuous deformation analysis method, taking the underground cavern group of Sichuan Ba Di hydropower station as the research background, the mechanical parameters in the numerical simulation take into account the randomness of joints in the rock mass and the uncertainty of the mechanical parameters of the rock mass, and then make the equivalent determination by the field measured data and the numerical simulation method. The dynamic construction method is studied, and the simulation calculation and analysis of the sequence of excavation, step excavation and step support are carried out, and the corresponding solutions are given so that the program can be more truly reflected in the actual construction process.
5. the coupling problem of the discontinuous deformation analysis method and the finite element method, the dynamic construction process, based on the OpenMP parallel problem, the plastic deformation mechanics model and the displacement convergence criterion of the anchor, are compiled into the calculation program in the VC++ platform by the C++ language, so that the program has a good function of analyzing the deformation of the block and the work of the engineering application. Yes.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV223

【参考文献】