节理岩体强度特征及宏观力学参数确定方法研究

发布时间：2018-04-22 14:25

本文选题：节理岩体 + 现场试验　；参考：《北京交通大学》2013年博士论文

【摘要】：由于岩体中包含了数量众多、分布形式复杂的结构面,从而使岩体力学性质具有尺度效应和高度的不均匀性、不连续性和各向异性。岩体的力学参数取值一直是岩体工作者关注的热点话题,目前隧道工程界常用的做法是根据现场围岩分级按规范的建议值进行选取,但是由于规范给出的建议值范围较大,可能造成工程不安全或过于保守。基于上述考虑,本论文以岩体强度为主线,采用现场试验和数值计算相结合,取得以下成果：(1)本文在大量现场工作的基础上,提出了一套利用小型试验设备制备裂隙化岩体试样的方法。(2)在分析Barton-Bandias经验公式的适用性基础上,借助二维离散元软件UDEC,提出了一种基于现场实测JRC(10cm长度)和结构面壁面回弹试验的结构面抗剪强度尺寸效应分析方法,并验证了方法的准确性。(3)利用Weierstrass随机分形函数建立了描述结构面起伏高度的三维曲面,通过三维离散元软件3DEC分析了抗剪强度的方向性,得出不同方向的抗剪强度相差10%以上的结论。(4)通过数值试验,系统分析了节理岩体的各向异性特征,得出含单结构面岩体随着围压的增加各向异性特征减弱,但强度差会增大；随着结构面组数的增加岩体的各向异性特征减弱,当含有4条以上节理时,岩体可以看做各向同性体。(5)在考虑尺寸效应的基础上通过数值计算得出了亚级分级条件下围岩的物理力学指标取值范围。(6)通过不同直径岩块试样的室内力学试验,提出了岩块尺寸效应的分析方法；提出了通过野外工程地质调查,概化得到工程地质模型,并选取具有代表性的岩块和结构面,然后分别进行岩块和结构面的室内实验和现场测量,得到岩块及结构面的物理力学参数,建立数值计算模型进行模拟,最终确定节理岩体物理力学指标的总体思路,经工程验证可以满足要求。
[Abstract]:Due to the large number and complex distribution of structural planes in rock mass, the mechanical properties of rock mass have scale effect and high inhomogeneity, discontinuity and anisotropy. The value of mechanical parameters of rock mass has always been a hot topic concerned by rock mass workers. At present, the commonly used method in tunnel engineering is to select the recommended value according to the site surrounding rock classification according to the code, but because of the large range of the suggested value given by the code, The project may be unsafe or too conservative. Based on the above considerations, this paper takes the rock mass strength as the main line, adopts the combination of field test and numerical calculation, and obtains the following results: 1) on the basis of a great deal of field work, A method of preparing fractured rock mass samples by using small test equipment is presented. Based on the analysis of the applicability of Barton-Bandias empirical formula, With the help of two-dimensional discrete element software UDEC, a method for analyzing the size effect of shear strength of structural plane based on the measured JRC(10cm length in situ and the springback test on the wall surface of the structural plane is presented. The accuracy of the method is verified. (3) using Weierstrass random fractal function, a 3D surface is established to describe the height of structure surface fluctuation, and the directivity of shear strength is analyzed by means of 3D discrete element software 3DEC. It is concluded that the shear strength difference of different directions is more than 10%. (4) through numerical experiments, the anisotropic characteristics of jointed rock mass are systematically analyzed. It is concluded that the anisotropic characteristic of rock mass with single structure plane decreases with the increase of confining pressure, but the strength difference increases. With the increase of the number of structural planes, the anisotropic characteristics of rock mass weaken, when there are more than 4 joints, The rock mass can be regarded as isotropic body. On the basis of considering the size effect, the range of the physical and mechanical indexes of surrounding rock under the condition of subgrade classification is obtained by numerical calculation. The range of physical and mechanical indexes of rock mass with different diameters is obtained through the indoor mechanical tests of rock samples with different diameters. An analysis method for the size effect of rock block is put forward, and the engineering geological model is obtained by field engineering geological survey, and the representative rock block and structural plane are selected. Then, the physical and mechanical parameters of rock block and structural plane are obtained by indoor experiments and field measurements, and the numerical calculation model is established to simulate the physical and mechanical parameters of jointed rock mass. Finally, the overall idea of physical and mechanical index of jointed rock mass is determined. It can meet the requirements after engineering verification.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

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