隧洞围岩体力学参数演化规律及工程应用研究
发布时间：2018-11-03 14:47
【摘要】：隧洞开挖过程中,应力重分布造成硐室周围岩体的刚度、强度参数发生变化,影响岩体变形和强度特征,直接关系到围岩体的稳定性。本文综合运用室内试验、理论分析、数值模拟及现场试验等方法,对围岩体力学参数的演化规律,进行了系统的研究,主要包括：(1)基于常规三轴压缩试验(围压：5-40MPa),研究了不同围压条件下砂岩、花岗岩变形、强度、破坏形式等特征。通过分析裂隙初始应力、裂隙贯通应力、峰值应力与围压的关系,得出砂岩、花岗岩特征应力对应的强度参数,研究了岩石压缩破坏前强度参数的变化规律。(2)在Mohr-Coulomb准则框架下,以塑性剪切应变为内变量,通过试验获取了砂岩、花岗岩强度参数的演化规律。Weibull函数和Lognormal函数可以较好地描述强度参数的初值、残值和演化规律。内摩擦角表现出先强化后弱化的特点。在FLAC3D内置应变软化模型中调用强度参数,模拟岩石三轴压缩过程,模拟的应力应变曲线表现出峰前硬化、峰后软化特征,峰值强度、残余强度与试验值平均相对误差分别为4.14%和11.42%。(3)工程开挖时,围岩体刚度会因为卸荷和冲击扰动而劣化。通过在扰动岩体中钻芯取样及试验测定,分析弹性模量值在围岩中的分布状态。基于扰动程度和扰动范围双重因素,提出孔深-弹性模量法,以归一化和积分形式给出围岩扰动系数的计算公式,评价扰动岩体弹性模量的劣化程度。将弹性模量法分析的扰动系数,与传统声波法测定值相比较,验证了弹性模量劣化评价方法的合理性,并对扰动岩体弹性模量进行修正(4)基于围岩体强度演化模型和刚度劣化研究,考虑围压和剪胀角等因素,对圆形隧洞平面问题的弹塑性解析解进行了修正。以集安引水隧洞圆形主洞为例,采用修正后的隧洞弹塑性解析程序,研究了支护力对围岩塑性区范围和变形的作用,得出塑性区半径和支护力呈指数关系。同时发现随着岩体弹性模量劣化程度加剧,塑性区范围近似线性扩大,围岩收敛位移近似指数型增长,弹性模量劣化是洞壁附近围岩变形大的重要原因。将修正前后的弹塑性解析值进行了对比。并将修正前后计算的位移值与实测值相比较,修正计算值与实测值更为接近,验证了围岩体刚度强度演化规律的合理性。(5)另外,基于围岩体刚度强度演化规律,数值模拟了集安引水隧洞城门形支洞掌子面推进过程中围岩位移场、应力场、塑性区和弹性应变能的演化规律。开挖全过程主应力改变、位移释放主要集中在掌子面前后[-D,D](D为隧洞直径)区间。模拟计算的位移值与后期监测数据相对误差8.63%,验证了围岩体力学参数演化规律的准确性。
[Abstract]:During the tunnel excavation, the stress redistribution causes the change of the stiffness and strength parameters of the surrounding rock mass, which affects the deformation and strength characteristics of the rock mass and directly relates to the stability of the surrounding rock mass. In this paper, the evolution law of surrounding rock mechanics parameters is systematically studied by means of indoor test, theoretical analysis, numerical simulation and field test. The main contents are as follows: (1) based on the conventional triaxial compression test (confining pressure: 5-40MPa), the characteristics of sandstone, granite deformation, strength and failure form under different confining pressures are studied. By analyzing the relationship between initial stress, fracture through stress, peak stress and confining pressure, the strength parameters corresponding to the characteristic stress of sandstone and granite are obtained. The variation of strength parameters before compression failure of rock is studied. (2) under the framework of Mohr-Coulomb criterion, the sandstone is obtained by experiments with plastic shear strain as internal variable. Weibull function and Lognormal function can describe the initial value, residual value and evolution law of strength parameter. The angle of internal friction shows the characteristic of strengthening first and then weakening. The strength parameters were transferred into the FLAC3D strain softening model to simulate the triaxial compression process of rock. The stress-strain curves showed pre-peak hardening, post-peak softening and peak strength. The average relative error between residual strength and test value is 4.14% and 11.42% respectively. (3) during excavation, the stiffness of surrounding rock body will be degraded by unloading and impact disturbance. The distribution of elastic modulus in surrounding rock is analyzed by sampling and testing the core in disturbed rock mass. Based on the dual factors of disturbance degree and disturbance range, the method of pore depth and elastic modulus is put forward, and the calculation formula of disturbance coefficient of surrounding rock mass is given in the form of normalization and integral to evaluate the deterioration degree of elastic modulus of disturbed rock mass. Comparing the perturbation coefficient of the elastic modulus method with the traditional acoustic wave method, the rationality of the method for evaluating the degradation of elastic modulus is verified. The elastic modulus of disturbed rock mass is modified. (4) based on the strength evolution model of surrounding rock mass and the study of stiffness deterioration, the elastic-plastic analytical solution of the plane problem of circular tunnel is modified by taking into account the factors of confining pressure and shear-expansion angle. Taking the circular main tunnel of Ji'an diversion tunnel as an example, the effect of supporting force on the range and deformation of surrounding rock plastic zone is studied by using the modified elastic-plastic analytical program, and the exponential relationship between the radius of plastic zone and the supporting force is obtained. At the same time, it is found that with the deterioration of elastic modulus of rock mass increasing, the range of plastic zone approximately expands linearly, the convergent displacement of surrounding rock increases approximately exponentially, and the deterioration of elastic modulus is an important reason for the large deformation of surrounding rock near the wall of the cave. The elastoplastic analytical values before and after the correction are compared. Compared with the measured values, the calculated displacement values are closer to the measured values, which verifies the rationality of the evolution law of the stiffness and strength of the surrounding rock mass. (5) in addition, based on the evolution law of the stiffness and strength of the surrounding rock mass, The evolution of displacement field, stress field, plastic zone and elastic strain energy of surrounding rock during the advance of the face of the gate branch tunnel in Ji'an diversion tunnel are numerically simulated. During the whole process of excavation, the main stress changes, and the displacement release is mainly in the section before and after the face of the palm [-DU D] (D is the diameter of the tunnel). The relative error between the calculated displacement value and the later monitoring data is 8.63, which verifies the accuracy of the evolution law of the surrounding rock physical parameters.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV554
本文编号：2308103
[Abstract]:During the tunnel excavation, the stress redistribution causes the change of the stiffness and strength parameters of the surrounding rock mass, which affects the deformation and strength characteristics of the rock mass and directly relates to the stability of the surrounding rock mass. In this paper, the evolution law of surrounding rock mechanics parameters is systematically studied by means of indoor test, theoretical analysis, numerical simulation and field test. The main contents are as follows: (1) based on the conventional triaxial compression test (confining pressure: 5-40MPa), the characteristics of sandstone, granite deformation, strength and failure form under different confining pressures are studied. By analyzing the relationship between initial stress, fracture through stress, peak stress and confining pressure, the strength parameters corresponding to the characteristic stress of sandstone and granite are obtained. The variation of strength parameters before compression failure of rock is studied. (2) under the framework of Mohr-Coulomb criterion, the sandstone is obtained by experiments with plastic shear strain as internal variable. Weibull function and Lognormal function can describe the initial value, residual value and evolution law of strength parameter. The angle of internal friction shows the characteristic of strengthening first and then weakening. The strength parameters were transferred into the FLAC3D strain softening model to simulate the triaxial compression process of rock. The stress-strain curves showed pre-peak hardening, post-peak softening and peak strength. The average relative error between residual strength and test value is 4.14% and 11.42% respectively. (3) during excavation, the stiffness of surrounding rock body will be degraded by unloading and impact disturbance. The distribution of elastic modulus in surrounding rock is analyzed by sampling and testing the core in disturbed rock mass. Based on the dual factors of disturbance degree and disturbance range, the method of pore depth and elastic modulus is put forward, and the calculation formula of disturbance coefficient of surrounding rock mass is given in the form of normalization and integral to evaluate the deterioration degree of elastic modulus of disturbed rock mass. Comparing the perturbation coefficient of the elastic modulus method with the traditional acoustic wave method, the rationality of the method for evaluating the degradation of elastic modulus is verified. The elastic modulus of disturbed rock mass is modified. (4) based on the strength evolution model of surrounding rock mass and the study of stiffness deterioration, the elastic-plastic analytical solution of the plane problem of circular tunnel is modified by taking into account the factors of confining pressure and shear-expansion angle. Taking the circular main tunnel of Ji'an diversion tunnel as an example, the effect of supporting force on the range and deformation of surrounding rock plastic zone is studied by using the modified elastic-plastic analytical program, and the exponential relationship between the radius of plastic zone and the supporting force is obtained. At the same time, it is found that with the deterioration of elastic modulus of rock mass increasing, the range of plastic zone approximately expands linearly, the convergent displacement of surrounding rock increases approximately exponentially, and the deterioration of elastic modulus is an important reason for the large deformation of surrounding rock near the wall of the cave. The elastoplastic analytical values before and after the correction are compared. Compared with the measured values, the calculated displacement values are closer to the measured values, which verifies the rationality of the evolution law of the stiffness and strength of the surrounding rock mass. (5) in addition, based on the evolution law of the stiffness and strength of the surrounding rock mass, The evolution of displacement field, stress field, plastic zone and elastic strain energy of surrounding rock during the advance of the face of the gate branch tunnel in Ji'an diversion tunnel are numerically simulated. During the whole process of excavation, the main stress changes, and the displacement release is mainly in the section before and after the face of the palm [-DU D] (D is the diameter of the tunnel). The relative error between the calculated displacement value and the later monitoring data is 8.63, which verifies the accuracy of the evolution law of the surrounding rock physical parameters.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV554
【参考文献】
相关期刊论文 前1条
1 邓楚键;郑颖人;王凯;高飞;;有关岩土材料剪胀的讨论[J];岩土工程学报;2009年07期
，本文编号：2308103
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