公路隧道脆性岩体岩爆机理与模拟方法研究

发布时间：2018-06-15 21:54

本文选题：岩爆 + 声发射　；参考：《北京科技大学》2015年博士论文

【摘要】：近几年随着我国公路、铁路等基础设施建设的大力发展,在隧道建设中岩爆灾害时有发生,随着洞室埋深的不断增加,深部岩体的复杂力学形为也越显突出,伴之而来的工程地质问题也越来越多。因此开展公路隧道脆性岩体岩爆机理与模拟方法的研究具有重要的意义。本文以张(家口)石(家庄)高速公路黑石岭隧道为项目背景,进行实地调查、岩石声发射Kaiser效应地应力量测、室内岩石力学试验、室内岩爆模拟试验、声发射能量及时频分析、数值模拟等方法,分析了公路隧道脆性岩体在埋深不足250m时岩爆发生的机制,并建立了二维圆形隧道围岩力学行为的连续-离散耦合分析模型,从宏-细观角度深入开展不同围压条件下圆形隧道围岩变形破坏机理研究,本论文取得的主要研究成果如下： (1)区域工程地质环境调查及影响因素分析。通过对隧道隧址区的地层、构造、水文、地质条件及活动断裂的分布情况进行调查,认为岩爆至少与以下各因素有关：地应力和围岩岩性、岩体结构、地质构造、不连续面性状、工程埋深、岩体工程的规模和形状、工程布置、开挖等因素。 (2)地应力测量及分析。现场采集岩样进行了岩石声发射Kaiser效应地应力试验,测得3个测点的原始地应力值,确定了工程区地应力的量级大小。得到3个测点的最大主应力值均超过20MPa,得出了主应力没有随埋深增加而逐渐增大的变化趋势的结论,并结合工程现场岩体结构及尺寸效应和室内岩爆模拟实验,求得了岩爆的临界深度为202米。 (3)现场采集岩石试样进行室内岩石力学试验,测定岩石物理力学参数。通过利用中国矿业大学(北京)研发的深部岩爆过程模拟试验系统,进行岩爆破坏模式及发生机制分析,获得了坚硬白云岩受力并发生岩爆破坏全过程的应力应变、声发射及破坏特征等属性,并利用傅里叶变换和Gutenberg-Richter关系式对岩样声发射能量及频谱特征进行分析和b值拟合,发现岩样在发生破坏时b值出现且呈降低趋势,在180kHz(175-210kHz)高频段的幅值与应力峰值变化相对应且大部分都满足b值关系式,声发射能量较多的岩样,岩爆发生时破坏也较为严重。 (4)基于颗粒流理论,通过平行黏结模型和光滑节理模型相结合再现矿物颗粒的不规则构造,并重现了脆性岩石的力学特性试验如抗拉、单轴压缩及不同围压下的三轴压缩试验,表明了GBM颗粒流模型能模拟抗压与抗拉强度比大于10的脆性材料破裂,能真实反映脆性岩石变形破坏的全过程。 (5)卸载岩爆PFC数值模拟结果表明,根据应力环境的变化,卸载岩爆试验进程可分为平静期、局部颗粒弹射期、发展期及最终爆发期等4种状态,瞬时岩爆发生时的颗粒黏结破裂机制以张拉型为主、剪切型破裂为辅,宏观表现为端部碎裂、中部弹射剥落特征。模拟试验再现了不同应力状态下的岩样细观破裂过程及机制,为岩爆产生的判别与验证提供了有效手段,为岩爆试验研究提供了一种新的有效途径。 (6)基于有限差分理论及颗粒流理论,建立了二维圆形隧道围岩力学行为的连续-离散耦合分析模型,从宏-细观角度深入开展了不同围压条件下圆形隧道围岩变形破坏机理研究。通过与理论计算、试验结果的对比分析,研究表明在低围压条件下,当水平围压与垂直围压相等,相同径向距离处的围岩变形量近似相等,均指向圆心。随着围压不断增大,破裂总数逐渐增多；在高围压条件下,当侧压系数K大于1,围岩破坏主要集中在隧道顶板、底板,当侧压系数K小于1,围岩破坏主要集中在隧道两帮,破坏形态均呈“毡帽形”,帽口朝向隧道中心。当侧压系数K等于1,围岩破坏表现出明显的分区破裂化现象。本文在研究过程中,取得了以下创新性成果：(1)建立了一种采用声发射波形频段幅值、能量变化判别岩爆的方法,揭示了声发射波形频段幅值、能量变化与岩爆之间的量化关系；(2)建立了一种基于GBM模型研究脆性岩石破坏力学特征及声发射事件识别与定位的方法：(3)建立了隧道围岩力学行为的连续-离散耦合分析方法,从宏-细观角度深入揭示了不同围压条件下圆形隧道围岩变形破坏机理。本文中的研究方法及相关成果可作为一种新的研究手段为复杂地质条件下各类隧道工程问题的科学分析、判别与验证提供有力支撑。
[Abstract]:In recent years, with the development of the highway and railway infrastructure construction in China, the rock burst disaster occurred in the tunnel construction. With the continuous increase of the depth of the cave, the complex mechanics shape of the deep rock mass is also more prominent, and more and more engineering geological problems are accompanied by it. Therefore, the mechanism of rock burst in the brittle rock mass of the highway tunnel is carried out and the mechanism of rock burst is carried out. The study of simulation method is of great significance.
Based on the project background of the heshiling tunnel of the Zhang (Jiazhuang) stone (Jiazhuang) Expressway, this paper carries out a field investigation, the rock acoustic emission Kaiser effect stress measurement, the laboratory rock mechanics test, the indoor rock burst simulation test, the acoustic emission energy time frequency analysis, the numerical simulation and so on, to analyze the rock of the highway tunnel brittle rock when the buried depth is less than 250m. The mechanism of explosion occurred and the continuous discrete coupling analysis model of the mechanical behavior of the two dimensional circular tunnel surrounding rock was established. From the macro meso angle, the deformation and failure mechanism of the surrounding rock under different confining pressure was studied. The main achievements of this paper are as follows:
(1) investigation of regional engineering geological environment and analysis of influencing factors. Through the investigation of the formation, structure, hydrology, geological conditions and distribution of active faults in tunnel and tunnel sites, it is considered that rock burst is at least related to the following factors: geostress and rock lithology, rock structure, geological structure, discontinuities, engineering burial depth, rock engineering Size and shape, engineering layout, excavation and other factors.
(2) geostress measurement and analysis. The in-situ stress test of rock acoustic emission Kaiser effect was carried out on the site. The original in-situ stress values of the 3 points were measured and the magnitude of the stress in the engineering area was determined. The maximum principal stress values of the 3 measured points were more than 20MPa, and the main stress did not gradually increase with the increase of the depth of the buried depth. The critical depth of rockburst is 202 meters, according to the conclusion of the project and combined with the rock mass structure and size effect and the indoor rock burst simulation experiment.
(3) the rock specimens were collected on the site to carry out the laboratory rock mechanics test and determine the rock physical and mechanical parameters. By using the deep rock burst simulation test system developed by the China University of Mining and Technology (Beijing), the rock burst failure mode and the mechanism were analyzed, and the stress and strain of the hard dolomite were obtained and the rock burst was damaged. The characteristic of emission and destruction characteristics, and the analysis of acoustic emission energy and spectrum characteristics of rock samples by Fourier transform and Gutenberg-Richter relation and b value fitting, it is found that the b value appears and decreases when the rock sample is destroyed. The amplitude value of the 180kHz (175-210kHz) high frequency section corresponds to the variation of the peak stress peak and most of which satisfy the B. In the case of rock samples with higher energy of acoustic emission, the failure of rock burst is more serious.
(4) based on the theory of particle flow, the irregular structure of mineral particles is reproduced by the combination of parallel bonding model and smooth joint model, and the mechanical properties of brittle rocks, such as tensile, uniaxial compression and three axial compression tests under different confining pressure, are reproduced, which shows that the GBM particle flow model can simulate the brittleness of compression and tensile strength greater than 10. The rupture of material can reflect the whole process of brittle rock deformation and failure.
(5) the numerical simulation results of unloaded rock burst PFC show that, according to the change of stress environment, the process of unloading rock burst test can be divided into 4 states, such as calm period, local particle ejection period, development period and final outbreak period, and the mechanism of particle bond rupture when instantaneous rock burst occurs is tensioning, shear fracture is supplemented, and macro performance is end fragmentation. The simulation test reproduces the mesoscopic fracture process and mechanism of rock samples under different stress states, which provides an effective means for the identification and verification of rock burst, and provides a new effective way for rock burst test.
(6) based on the finite difference theory and the particle flow theory, a continuous discrete coupling analysis model of the mechanical behavior of the surrounding rock of a two-dimensional circular tunnel is established. From the macro meso angle, the deformation and failure mechanism of the surrounding rock of a circular tunnel under the conditions of different confining pressure is carried out. The comparison analysis of the experimental results and the theoretical calculation shows that the low confining pressure is shown. Under the condition that the horizontal confining pressure is equal to the vertical confining pressure, the surrounding rock deformation at the same radial distance is approximately equal and points to the center. As the confining pressure increases, the total number of fracture increases gradually. Under the condition of high confining pressure, when the lateral pressure coefficient K is greater than 1, the failure of the surrounding rock is mainly concentrated on the tunnel roof, and the bottom plate, when the lateral pressure coefficient is less than 1, the failure of the surrounding rock is main. The two groups are concentrated in the tunnel. The damage forms are all felt "felt cap" and the cap and mouth face the center of the tunnel. When the lateral pressure coefficient K equals 1, the destruction of the surrounding rock shows a distinct division and fracture phenomenon.
In the course of the study, the following innovative achievements have been obtained: (1) a method of using the amplitude of acoustic emission wave band and energy change to distinguish rock burst is established. The amplitude of acoustic emission wave band and the quantitative relation between energy change and rock burst are revealed. (2) a GBM model is established to study the mechanical characteristics of brittle rock failure. The methods for identifying and locating acoustic emission events are: (3) a continuous discrete coupling analysis method is established for the mechanical behavior of tunnel surrounding rock. The deformation and failure mechanism of surrounding rock under the conditions of different confining pressure is deeply revealed from the macro meso angle.
The research methods and related achievements in this paper can be used as a new research means for scientific analysis of various tunnel engineering problems under complex geological conditions, and a strong support for discrimination and verification.
【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】：U451.2

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