非贯通节理岩体各向异性力学特性试验研究

发布时间：2018-03-06 01:09

本文选题：非贯通　切入点：节理岩体　出处：《三峡大学》2014年硕士论文　论文类型：学位论文

【摘要】：自然界中的岩体在漫长的地质演变过程中，往往被大小、形状、方向各异的结构面纵横切割，而形成具有一定结构特征的不连续岩体，由于结构面的存在，显然不连续岩体的力学特性要比完整岩石复杂很多。本文对非贯通节理岩体试件进行了声波波速测试、单轴压缩试验、常规三轴压缩试验和卸荷试验，研究了非贯通节理岩体的声学特性和加卸载条件下的力学特性，论文具体研究内容如下： 1)对试验所需的试验设备进行设计，，包括对岩石切割机进行满足试验要求的相关升级改造，改造后的切割机可以方便切割不同节理倾角、不同节理连通率的试件。 2)不同连通率、不同角度非贯通节理岩体的纵波波速测试，研究其声波波速随着节理连通率、节理倾角的变化特征以及衰减规律。结果表明随着节理连通率的增大，纵波波速在非贯通节理试件的中的传播速度在各个角度节理倾角下均有明显的减小趋势；在纵波波速衰减率对节理倾角的敏感性（敏感性用μ表示）大小依次为：μ0°μ30°μ45°μ60°μ90°。 3)完整岩石试件以及不同连通率(k=0.25、k=0.5、k=0.75)、不同角度(β=0°、β=30°、β=45°、β=90°、β=60°)非贯通节理岩体单轴压缩试验、不同围压水平(5MPa、10MPa、15MPa、20MPa)下常规三轴压缩试验、卸荷(峰前卸荷)试验；研究不同节理连通率、不同节理倾角非贯通节理岩体试件加卸载条件下的峰值强度、变形参数、强度参数、破坏形式等特征，并与完整试件进行对比分析。结果表明非贯通节理岩体加卸载条件下均表现出各向异性力学特性，且随着节理连通率的增大，这种各向异性特性表现的更为明显。 4)非贯通节理岩石试件在加卸载试验中所表现出来的力学特性、破坏形态、力学参数等具有明显差异，岩体加卸荷状态下具有不同的破坏机理；在卸荷条件下非贯通节理岩体试件均表现出明显的延性破坏特征，并且随着连通率的增大这种特征表现得更加明显。 5)直线型Mohr-Coulomb强度准则、抛物线型Mohr-Coulomb强度准则和Hoek-Brown强度准则均能较好地表述非贯通节理岩体主应力之间的相互关系，相比而言，抛物线型Mohr-Coulomb强度准则和Hoek-Brown强度准则更能准确表述非贯通节理岩石试件加卸载条件下主应力之间的相互关系。 6)根据节理岩体的加卸载试验，对单一非贯通节理岩体的加卸载屈服准则,进行了探讨，将岩体的非贯通节理看做是一种损伤，根据岩体破坏过程的应力-应变曲线变化特征，引入损伤变量，将加卸荷破坏曲线分为线弹性段、理想弹塑性段、非线性应变软化段、线性残余塑性流动段4段，并推导了相应的本构关系。
[Abstract]:In the long process of geological evolution, rock mass in nature is often cut vertically and horizontally by structural planes of different sizes, shapes and directions, and discontinuous rock masses with certain structural characteristics are formed because of the existence of structural planes. It is obvious that the mechanical properties of discontinuous rock mass are much more complicated than that of intact rock mass. In this paper, the acoustic wave velocity, uniaxial compression test, conventional triaxial compression test and unloading test are carried out for non-transfixion rock mass specimens. The acoustical characteristics and mechanical properties of non-through-jointed rock mass under loading and unloading conditions are studied in this paper. The main contents of this paper are as follows:. 1) the test equipment needed for the test is designed, including the upgrading of rock cutting machine to meet the test requirements. The modified cutting machine can easily cut specimens with different joint inclination and different joint connectivity. 2) the longitudinal wave velocities of rock masses with different connectivity and angles are measured, and the variation characteristics of acoustic wave velocities with joint connectivity, joint inclination and attenuation are studied. The results show that with the increase of joint connectivity, The velocities of P-wave wave propagating in non-transfixion joint specimens have an obvious decreasing trend at all angles, and the sensitivity (expressed in 渭) of the attenuation rate of P-wave velocities to the inclination angles of joints is 渭 0 掳渭 30 掳渭 45 掳渭 60 掳渭 90 掳. 3) intact rock specimens and different connectivity ratios of 0.25kU 0.5kL 0.75, different angles (尾 0 掳, 尾 30 掳, 尾 -45 掳, 尾 -90 掳, 尾 -60 掳), uniaxial compression tests of non-penetrating jointed rock masses, conventional triaxial compression tests with different confining pressure levels of 5MPa 10MPa 15MPa / 20MPa, unloading tests (unloading before peak loading), and studies on the connectivity of different joints. The characteristics of peak strength, deformation parameter, strength parameter, failure form and so on under the condition of loading and unloading of non-transfixion jointed rock mass specimens with different joint dip angles, The results show that the anisotropic mechanical properties of rock mass are anisotropic under loading and unloading conditions, and the anisotropy is more obvious with the increase of joint connectivity. 4) there are obvious differences in mechanical properties, failure patterns and mechanical parameters of non-through jointed rock specimens in loading and unloading tests, and there are different failure mechanisms under loading and unloading of rock mass. Under unloading condition, the specimens of non-transfixible jointed rock mass show obvious ductile failure characteristics, and this characteristic is more obvious with the increase of connectivity. 5) the linear Mohr-Coulomb strength criterion, parabolic Mohr-Coulomb strength criterion and Hoek-Brown strength criterion can better describe the relationship between the principal stresses of non-transfixion jointed rock mass. The parabolic Mohr-Coulomb strength criterion and the Hoek-Brown strength criterion can more accurately describe the relationship between the principal stresses under the loading and unloading conditions of rock specimens with non-transfixion joints. 6) according to the loading and unloading test of jointed rock mass, the loading and unloading yield criterion of single non-transfixion jointed rock mass is discussed. The non-transfixion joint of rock mass is regarded as a kind of damage, and according to the characteristic of stress-strain curve of rock mass failure process, By introducing damage variable, the failure curve of loading and unloading is divided into four sections: linear elastic section, ideal elastic-plastic section, nonlinear strain softening section, linear residual plastic flow section, and the corresponding constitutive relation is derived.
【学位授予单位】：三峡大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU45

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