【作者】 鲁光银；

【导师】 朱自强；

【作者基本信息】 中南大学 ， 安全信息工程， 2009， 博士

【摘要】 隧道工程作为一项隐蔽工程,当掌子面前方地质情况不明时,极易造成塌方、冒顶、突水突泥等突发性地质灾害,不但影响施工进度,还极易造成设备被埋、人员丧亡等重大安全事故,给国民经济和人民生命财产造成重大损失。超前探测是隧道地质灾害预测与防治的基础,围岩分级是隧道地质灾害稳定性评价与处治方案制定的依据。然而,隧道地质灾害反射波法探测中,由于地震波场异常复杂、且相互重叠,难以有效的识别与分离,无法满足隧道超前探测中高精度和高分辨率的要求;另外,隧道不良地质灾害体的处置中,传统岩体分级方法由于缺乏有效、合理的围岩级别判定体系,无法准确评价隧道围岩稳定性并指导施工,也难以满足隧道地质灾害处治需要。针对这些问题,作者在多项省部级科研课题的联合资助下,在隧道典型地质灾害模型的地震波场正演模拟、多波多分量资料的偏移成像、以及隧道围岩的动态F-AHP分级等方面进行了研究和探索,主要开展了以下工作:(1)在分析一阶速度-应力弹性波方程的任意偶数阶时间-空间精度交错网络差分格式,并探讨其稳定性条件和克服数值频散方法的基础上,针对隧道反射波法超前探测的检波观测系统,作者详细的探讨了隧道地震波场正演模拟的边界条件,系统推导了其边界条件方程及交错网络差分计算格式,并设置了震源函数,为隧道波场正演数值模拟与程序编制打下了基础。(2)采用Visual C++和MATLAB可视化程序设计语言,编制了适用于任意复杂介质模型的隧道波场正演模拟程序,并应用于隧道掘进中断层、软弱夹层、溶洞等几种典型地质灾害模型的正演计算,获取了相应模型不同时刻的波场快照和地震合成记录。正演模拟结果清晰的反映出到初至波、反射波、透射波及多次波等各类地震波的运动学和动力学特征,总结了隧道地震波场的传播规律,加深对隧道波场快照的认识,为隧道反射波探测资料的反演解释提供理论技术基础。(3)在详细分析目前常规隧道波场偏移成像算法中,采用传统标量波波场处理方法,由于隧道波场复杂、难以完全分离导致偏移成像准确度和精度较低,无法满足隧道地质灾害精确预报的基础上,针对隧道反射波超前探测中多波多分量数据的特点,采用矢量波波场处理方法,在隧道复杂条件下实现了全波波动方程的逆时偏移成像,较传统隧道波场偏移成像方法更适应隧道隐伏地质灾害体的超前探测与反演解释。(4)根据隧道工程特点,作者综合利用地质地球物理资料、测井资料、隧道工程资料和地震记录,提出了构建初始速度模型的综合方法,并在导出全波波动方程逆时延拓的交错网络差分计算格式以及求取逆时偏移成像条件的基础上,编制程序实现了隧道波场逆时偏移成像算法,应用于前述几种典型地质灾害模型和隧道工程,获取了更准确和更清晰的偏移成像剖面,取得了较好的地质效果,更有利于隧道反射波超前探测资料的地质解释。(5)在分析传统隧道围岩分级方法难以满足隧道地质灾害处置需要局限性的基础上,作者引入层次分析法(AHP法)动态调整隧道围岩分级的影响因子,提出了采用模糊数学理论来确定影响因子的模糊权重的计算方法,编制程序实现了隧道围岩动态F-AHP分级算法,并应用于隧道工程。工程应用结果表明,较传统RMR分级,隧道围岩动态F-AHP分级,提高了隧道围岩分级的准确度,为隧道地质灾害评价与处置提供更为精确的依据。更多还原

【Abstract】 Tunnel project belongs to the underground covert engineering. When there are unknown geological conditions ahead of construction, such badness geological bodies as faults, underground rivers, soft interlayer, karst, can easily cause to unexpected geological disasters, such as collapse, water gushing, mud dashing, rock burst, etc.. All these unexpected geological disasters not only delay the construction schedule, but also bring about equipment easily buried, staff bereavement, which cause to heavy losses for the national economy, people’s lives and properties. Tunnel detection is foundation of the geological disaster prediction and prevention, and rock mass classification is the basis for stability evaluation and treatment project for the geological disaster. But during tunnel geological hazards detection ahead of construction by reflected wave method, wave field is abundant, overlapped, and very complex, which cause it is difficult to effectively identify and separate. Conventional scalar wave field disposal methods are difficult to satisfy the requirements of high-precision and high-resolution. At the same time, for lack of an effective and rational system to determine the level of rock mass, traditional methods of rock mass classification cannot manifest the small difference of factors and guide the construction. So it is difficult to meet the requirement for the disposal of geological disasters in the tunnel. Aiming to these problems, under jointly funded research projects of the Ministry of Communication and Hunan province, the author studies and discusses the staggered-grid finite-difference simulation of elastic wave in tunnel situation, migration imaging for multi-wave and multi-component data of the reflected wave, and tunnel rock mass classification by dynamic F-AHP method. Then the paper develops the below works:(1)After deriving the first-order coupled elastic equations of 2D particle velocity and stress and any order accurate time and space formulation of staggered-grid finite-difference scheme, and discussing the stability condition of staggered-grid finite-difference method and seismic wave numerical dispersion, the author discusses the free boundary conditions and artificial boundary conditions detailed aiming at the special observation system for detection ahead of tunnel by reflected wave method, and then derives its finite-different format. All these work could set the foundation for the tunnel seismic wave field forward simulation and the according program compiling.(2)Combining with Visual C++ and MATLAB programme design language, the author compiles detection forward procedures for any complex model of tunnel disasters. Then by applied into the forward simulation calculation of typical project geological models in tunnel such as fault, karst whole, and get the wave field snapshot and seismic record of the according models. In these results, it could clearly observe the kinematics and dynamics characteristics of primary wave, reflection wave, transmission wave and multiple wave of reflection. By analysis these forward record and wave field snapshot, it could understand the propagation regulation of seismic wave field more profundity, improve comprehension to tunnel seismic wave field snapshot and provide the technology support to the inversion interpretation.(3)For the tunnel wave field is very complex and it is difficult to identify and separation effectively, in traditional wave field disposal methods, the scalar-wave field disposal methods would affect the low accuracy of disposal, and it could not satify the forecast of geological disaster. Then aiming at characters of multi-wave and multi-component by reflected wave methods detection in tunnel, the author adopts the vector wave field method and implements reverse-time migration based on full wave equation in complex tunnel condition. It could more adapted detection and interpretation for complicated geological structures in tunnel.(4) Considering the characters of tunnel engineering, the author proposes an integrated methods for the initial velocity model construction by making use of geology-geophysics data, well data, tunnel engineering data and seismic records. After deriving the staggered-grid finite-difference scheme for inverse time calculation, the author compiles procedures and realized the reverse-time migration arithmetic for tunnel wave field. Then it is applied into the geological models and tunnel engineering, and gets the more accuracy and clearly inversion imaging effect, which can improve imaging resolution and conducive geological interpretation for reflection wave data in tunnel condition.(5)After analyzing the limitations of traditional methods of rock mass classification, combined with of tunnel geological disasters detection and prevention, the author adjusts impact factors of tunnel rock mass classification dynamically by AHP method, calculates factors weights by fuzzy math theory, and compiles procedures for the rock mass classification by dynamic F-AHP arithmetic. Then it is applied into the tunnel engineering. The results show that the method is closer to the actual situation during tunnel excavation than traditional RMR, which raise the accuracy of rock mass classification and can supply more sufficient basis for the evaluation and disposal of the tunnel geological disaster.更多还原