深埋隧道围岩脆性破裂的微震监测及岩爆解译与预警研究

发布时间：2019-07-03 15:22

【摘要】：一系列中国西部重大典型工程项目的相继投入和建设(如“川藏铁路”、“川藏高速公路”、“泛亚铁路网”等),促使了我国西部大型工程项目以较快的速度不断发展,并产生了众多的地下工程及隧道工程。并且,由于隧道工程建设面临复杂的地形和地质条件,往往使其具有“深埋长大”的特点。在隧道掘进的卸荷作用下,高地应力围岩内储存的能量急剧释放,致使岩体突然脱离围岩,并伴有声音和弹射等现象,这种现象被称为岩爆。岩爆通常具有突发性、猛烈性和严重的破坏性,会给工程建设带来严重安全隐患。微震监测(Microseismic Monitoring)是一种针对岩体微破裂在空间发育的监测技术。该项技术可用于采集隧道围岩破裂产生的地震波,再利用波形分析获取微震事件的时间、位置以及震源强度等信息。通过对一定区域内微震事件及发育速率的捕获,微震监测可以在地下工程岩爆预警上发挥重要作用。然而,目前应用于深埋隧道围岩的微震监测精度还有待提高,包括了震源位置的定位精度以及受震源位置影响的震源参数的精度。此外,利用微震信息深入理解岩爆的孕育过程和机理是实现对隧道围岩岩爆灾害有效预警的关键,即利用微震信息解译岩爆的发育过程并提高对其预测预警的有效性还需要进行更加深入的研究。基于此,本文从“震源定位技术”、“微震监测分析”和“岩体力学模拟”三种研究角度,即将“地震波动分析”与“岩体力学分析”相结合,以工程实例中的“深埋隧道围岩”为研究对象,开展了岩体脆性破裂及岩爆发育过程的模拟与解译研究。在此基础上,建立隧道掘进的岩爆预警方法,并结合工程实例阐述了此预警方法的实施流程,最终目的为实现对岩爆过程的合理解译与有效预警。通过研究,获得了如下主要成果和认识:(1)针对深埋隧道围岩破裂的微震监测,通过对微震监测系统的布置方案、岩体波速确定和现场滤噪方法的研究,构建了一套适用于交通隧道施工的移动式微震监测系统,实现了对隧道围岩微震活动的动态连续监测。(2)为提高隧道围岩微震事件的定位精度,在传统的震源定位方法中引入地震波类型判识、隧道围岩波速模型和残差计算准则,建立了隧道围岩的震源定位方法。对于隧道围岩的波速模型,考虑穿越隧道挖空段的洞壁面波传播效应,通过获取不同岩体泊松比情况下的面波与体波速度的比值,建立了基于传播路径的波速修正公式。在对已知位置人工爆破事件和未知位置微震事件的定位应用中,隧道围岩的震源定位方法获取了比传统定位方法精度更高的定位结果;在对传感器阵列布置方案影响定位精度的探讨中,双洞三断面交错布置方案获取了最合理的隧道围岩残差空间(最小的残差值和最合理的残差分布)以及精度最高的震源定位结果。(3)通过对典型隧道工程围岩微震震源参数分析和微震事件分类研究,从微震监测角度解译了岩爆的发育过程。米仓山隧道K49+920 K49+840岩爆段微震事件可在Log地震能量 Log地震矩空间中分为六个类型,并对应岩爆过程的能量积累、能量转移和能量释放阶段;锦屏二级水电站引水隧洞和辅助洞岩爆段微震事件可在视应力 Log地震矩空间中分为三个类型。根据矩张量反演及成份分解的结果,米仓山隧道岩爆段出现了大量的张拉破裂事件及相对较少的剪切破裂事件(包含张剪和压剪)。根据矩张量的双力偶分量,判识出围岩内具有两组明显发育趋势的滑移断裂面,并获得其方位及组合关系。(4)为使数值模型能反映实际岩体的脆性破裂机理及伴随产生的微震事件,搭建了联系两者的桥梁,即硬岩的脆性破裂模型。首先,基于粘结颗粒模型引入脆性指标对脆性破裂过程进行评估(储能系数、脆性系数和颗粒冲击动能),提出了反映岩石脆性破裂的微观参数调控原则。模拟岩样的各类力学试验(单轴压缩、三轴加卸载、真三轴加载)结果表明,脆性破裂过程具有特殊的破裂特征和能量演化规律:应力应变曲线呈现较高的变形模量,无明显的屈服阶段,以及迅速的应力跌落;一系列的连锁微破裂在峰后应力阶段的集中发生,使模拟岩样在较小应变时出现破裂的贯通,并产生呈“爆发式”增长的颗粒冲击动能;耗散能在峰后应力阶段急剧增加。其次,引入破裂源评估指标(破裂驱动力和应力降)量化破裂源的动力性质,并实现岩石破裂声发射事件及效应的模拟。最后,提出并组建ACDC-SRM-UJRM方法,实现了工程对象(宏观尺寸)仿真脆性岩体模型的建立,并阐述了其运转过程。(5)为解译和评估岩爆的发育过程及微震事件特征,建立了基于微震特征的岩体脆性破裂模拟方法。反馈于岩体脆性破裂模拟的震源信息可分为三类:震源参数、应力场方位和破裂机理。对紫荆隧道K13+670 K13+770段围岩脆性破裂进行了分析,并采用两种参数方案对比脆性和塑性围岩导致的不同破裂过程、微震事件分布及应力场演化。对米仓山隧道K49+920 K49+860段岩爆的分析表明,在岩爆过程中应力场各分量经历了分化、急增和陡降;体积应变经历了降低、轻微回弹和猛烈回弹。相关指标能较好的解译岩爆的发育过程及微震事件簇的力学效应,为预警岩爆提供了可能。(6)从微震监测分析和基于微震特征的岩体脆性破裂模拟两方面,对岩爆过程进行综合解译和判识,并以此为依据建立了基于岩爆孕育过程的隧道岩爆预警方法。以米仓山隧道左洞微震监测段K50+250 K50+180开展工程实例分析。在K50+230 K50+200段围岩开挖后,微震事件簇中出现了变形驱动型事件,体积应变出现回弹,动能出现抬升;对下一阶段开挖的模拟预测表明,此区域将发生破裂失稳,应对潜在岩爆进行预警。随后在K50+200 K50+180段围岩开挖中,岩爆发生在滞后桩号K50+210,证实了隧道掘进岩爆预警方法的有效性。
[Abstract]:The successive input and construction of a series of major typical engineering projects in western China (such as "Sichuan-Tibet Railway", "Sichuan-Tibet Expressway", "Trans-Asian Railway Network", etc.) have led to the rapid development of large-scale engineering projects in the west of China at a higher speed, and produced numerous underground engineering and tunnel projects. Moreover, because the tunnel construction is faced with complex terrain and geological conditions, it is often the characteristic of the "deep-buried growth". Under the unloading of the tunnel, the energy stored in the high-stress surrounding rock is rapidly released, so that the rock mass is suddenly separated from the surrounding rock and accompanied by the phenomena of sound and ejection, which is known as the rock burst. The rock burst usually has sudden, violent and serious damage, which can cause serious safety hazard to the project construction. Microseismic monitoring is a monitoring technique for microfracture of rock mass in space. The technique can be used to collect the seismic wave generated by the rupture of the surrounding rock of the tunnel, and then use the waveform analysis to obtain the information of the time, the position and the intensity of the source of the microseismic event. The microseismic monitoring can play an important role in the early warning of rockburst in underground engineering through the capture of microseismic event and development rate in a certain area. However, the accuracy of the micro-seismic monitoring applied to the surrounding rock of the deep-buried tunnel is still to be improved, including the positioning accuracy of the location of the source and the accuracy of the source parameter affected by the location of the source. In addition, in-depth understanding of the inoculation process and mechanism of the rock burst by using the micro-seismic information is the key to the effective early warning of the rock burst disaster of the tunnel surrounding rock, that is, the development process of the rock burst is interpreted by using the micro-seismic information and the effectiveness of the prediction and early warning is improved. On the basis of this, from the three research angles of "source location technology", "microseismic monitoring and analysis" and "mechanical simulation of rock mass", the "seismic wave analysis" and the "mechanical analysis of rock mass" are combined, and the "deep-buried tunnel surrounding rock" of the engineering example is the research object, and the simulation and interpretation of the brittle fracture and the rock burst development process of the rock mass are carried out. On this basis, the method of rock burst early warning for tunnel excavation is set up, and the implementation process of the early warning method is described in combination with the engineering examples, and the final purpose is to realize the reasonable interpretation and effective early warning of the rock burst process. Through the research, the following main results and the recognition are obtained: (1) The micro-seismic monitoring of the surrounding rock of the deep-buried tunnel is carried out, the arrangement scheme of the micro-seismic monitoring system, the determination of the wave velocity of the rock mass and the on-site noise filtering method are studied, A set of mobile micro-vibration monitoring system, which is suitable for the construction of traffic tunnel, is constructed, and the dynamic and continuous monitoring of the micro-seismic activity of the surrounding rock of the tunnel is realized. (2) In order to improve the positioning accuracy of the micro-seismic event of the tunnel surrounding rock, the seismic wave type identification, the tunnel surrounding rock wave velocity model and the residual calculation criterion are introduced in the traditional source location method, and the source positioning method of the tunnel surrounding rock is established. For the wave velocity model of the tunnel surrounding rock, the wave velocity correction formula based on the propagation path is established by taking into consideration the wave propagation effect of the hole wall surface wave passing through the hollow section of the tunnel, and by obtaining the ratio of the surface wave and the body wave velocity in the case of the Poisson's ratio of the different rock mass. in the method for positioning a known position manual blasting event and an unknown position micro-earthquake event, the source positioning method of the tunnel surrounding rock obtains a positioning result which is higher than that of the traditional positioning method, The two-hole three-section staggered arrangement scheme obtains the most reasonable residual space of the tunnel surrounding rock (the minimum residual value and the most reasonable residual distribution) and the highest accuracy of the source positioning result. (3) The development process of the rock burst is interpreted from the micro-seismic monitoring angle through the analysis of the micro-seismic source parameter and the micro-seismic event classification of the surrounding rock of the typical tunnel engineering. The microseismic event of the K49 + 920 K49 + 840 rock burst in the Mbin Mountain Tunnel can be divided into six types in the Log seismic energy Log seismic moment space and corresponding to the energy accumulation, energy transfer and energy release phase of the rock burst process; The micro-seismic event of the diversion tunnel and the auxiliary tunnel in Jinping II Hydropower Station can be divided into three types in the visual stress Log seismic moment space. Based on the results of the inversion of the moment tensor and the decomposition of the components, a large number of tension fracture events and relatively few shear fracture events (including shear and compression shear) occurred in the rock burst section of the Miangshan tunnel. According to the two-force couple component of the moment tensor, the slip fracture surface with two obvious development trends in the surrounding rock is identified, and the orientation and the combination relation are obtained. (4) In order to make the numerical model reflect the brittle fracture mechanism of the actual rock mass and the microseismic event, the brittle fracture model of the hard rock is set up. First, the brittle fracture process is evaluated (energy storage coefficient, brittleness coefficient and particle impact kinetic energy) based on the bonding particle model, and the micro-parameter regulation principle that reflects the brittle fracture of the rock is put forward. The results of various mechanical tests (single-axis compression, three-axis loading and unloading, true triaxial loading) of the simulated rock sample show that the brittle fracture process has special fracture characteristics and energy evolution rule: the stress-strain curve exhibits a high deformation modulus, no obvious yield phase, And a series of chain microfracture is concentrated in the post-peak stress stage, so that the simulated rock sample is broken through the small strain, and the particle impact kinetic energy in the "burst" growth is generated; and the dissipation can be rapidly increased at the post-peak stress stage. Secondly, the dynamic property of the fracture source is quantified by introducing the fracture source evaluation index (the fracture driving force and the stress drop), and the simulation of the acoustic emission events and effects of the rock crack is realized. Finally, the method of ACDC-SRM-UJRM is put forward and an ACDC-SRM-UJRM method is put forward, and the establishment of the brittle rock mass model of the engineering object (macro-size) is realized, and the operation process is described. (5) In order to interpret and evaluate the development of rock burst and the characteristics of microseismic events, a method for simulating the brittle fracture of rock mass based on microseismic characteristics is established. The seismic source information fed back to the brittle fracture simulation of the rock mass can be divided into three types: source parameter, stress field orientation and fracture mechanism. The brittle fracture of the surrounding rock of the K13 + 670K13 + 770 section of the Bauhinia tunnel is analyzed, and two parameters are used to compare the fracture process, the microseismic event distribution and the stress field evolution caused by the brittle and plastic surrounding rock. The analysis of the rock burst in the K49 + 920 K49 + 860 section of the Miangshan Tunnel shows that the stress field in the rock burst process has experienced the differentiation, the sharp increase and the steep drop, the volume strain experienced a decrease, a slight rebound and a violent rebound. The related indexes can better interpret the development process of the rock burst and the mechanical effect of the microseismic event cluster, and provide the possibility for the early-warning rock burst. (6) Based on the analysis of microseismic monitoring and the simulation of the brittle fracture of the rock mass based on the microseismic characteristics, the rock burst process is comprehensively interpreted and recognized, and the early warning method of the tunnel rock burst based on the rock burst inoculation process is established. The engineering example analysis is carried out in the left-hole micro-vibration monitoring section K50 + 250K50 + 180 in the Miangshan tunnel. After the surrounding rock of K50 + 230K50 + 200 section is excavated, a deformation driving type event occurs in the microseismic event cluster, the volume strain is spring-back, and the kinetic energy is raised; and the simulation prediction of the next phase excavation indicates that the region will crack and unstable and the potential rock burst shall be pre-warning. Then, in the surrounding rock excavation of the K50 + 200 K50 + 180 section, the rock burst occurred in the lagging pile No. K50 + 210, which confirmed the effectiveness of the method for early warning of the rock burst in the tunnel.
【学位授予单位】：成都理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U456;U451.2

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