【作者】 贾蓬；

【导师】 唐春安；

【作者基本信息】 东北大学 ， 工程力学， 2008， 博士

【摘要】 工程岩体往往被各种结构面所切割,使得工程岩体的性质具有明显的不均匀性。大量工程实践表明,在被结构面切割的岩体中开挖洞室后,常常出现洞室大变形、支护破坏,甚至洞室整体破坏失稳。因此,开展结构面影响下隧道围岩破坏机理研究对于采矿和地下结构工程实践都具有十分重要的意义。由于岩体表现出强烈的非均质性、各向异性和非连续性,采用解析的方法显然已经无法满足围岩稳定性分析的需要,而目前针对结构面对隧道稳定性影响的研究多是采用现场监测与相似材料模拟试验相结合或是采用统计的方法,这些方法多数只能给出研究的最终结果,而无法进行破坏过程演化机理的模拟与分析,从而使得许多理论与工程分析停留在“结果分析”上。尽管物理模型试验是工程结构破坏的主要研究手段,但物理模型试验不仅成本高、周期长,而且模型参数难以在有限个物理模型中调整,大大地限制了物理模型试验在隧道稳定性研究中的应用。更大的困难还在于,许多地质和工程诱发的灾害难以在实验室条件下进行物理模型试验研究。尽管国内外学者在围岩稳定性方面已经做了大量的工作,但是由于地下工程的复杂性,对于围岩的破坏机理至今并没有完全认识清楚,尤其是对受结构面影响下隧道围岩的渐进性破坏规律的认识仍然比较模糊。因此,本文抓住岩石为非均匀性材料的认识,采用损伤力学和统计理论的单元本构模型,利用能够反应岩体渐进破坏过程的岩石真实破坏过程分析软件(RFPA)数值模拟分析系统,利用有别于传统加载研究方式的强度折减方法,在现有理论基础上,将不良地质构造、地应力等因素与围岩的变形和损伤演化联系起来,通过在数值模拟中考虑围岩力学性质的逐步退化,建立了卸载作用下围岩变形、损伤与逐渐失稳破坏的分析模型,主要研究内容如下：将强度折减法应用于岩石隧道稳定性分析中,通过在数值模拟中考虑围岩力学性质的逐步弱化,研究了卸载作用下围岩变形、损伤与逐渐失稳破坏的机理和演化规律,对强度折减法在隧道稳定性分析中应用的可靠性作了充分评价,并阐明了它的优势；研究了层状顶板巷道围岩的变形破坏特征以及不同侧压、不同厚跨比条件下层状顶板的破坏机理；研究了位于被不同倾角软弱成层结构面切割的岩体中隧道的变形破坏特征在不同侧压比作用下的破坏失稳模式、隧道周边位移和隧道的安全储备问题,指出Goodman图解法判别层状岩体稳定性仅适用于水平地应力较小的情况。研究了水平地应力对深埋垂直板裂结构岩体中隧道围岩破坏机理的影响,指出了梁板理论应用于板裂结构岩体洞室稳定性评价的局限性。分析了隐含断层的分布位置和倾角对隧道围岩变形破坏机理及安全储备的影响；讨论了断层厚度和地应力对靠近隐含断层的隧道破坏失稳机制的影响并给出了含隐含断层岩体中隧道稳定性判别的方法。研究了被两组交叉节理切割的岩体中隧道围岩的稳定性及围岩破坏机制,研究了交叉节理的产状以及节理贯通程度对隧道破坏机制的影响,并分析了在不同侧压力系数条件下,隧道围岩的破坏机制和安全储备问题。基于联想1800高性能计算机,采用大规模科学数值计算方法,研究了互层状岩体中深埋单孔巷道和平行巷道围岩分区破裂现象的发生机制,揭示了分区破裂发生的条件及其影响因素。更多还原

【Abstract】 Engineering rock masses are cut by many kinds of structural planes which causes the obvious characteristic of heterogeneity. It is indicated by engineering practice that after excavation in the rock massed cut by structural planes, big displacement, local failure and even the failure of whole tunnel structures are often encountered. To study the failure mechanism of tunnel under the influence of structural planes is deemed to be very important to the mining and under ground engineering practice.Due to the heterogeneity, anisotropy and discontinuity of rock masses, the analytical method is insufficient to solve the complex stability problems of tunnel. Nowadays, the common way to analyze the influence of structural planes on tunnel stability is to use the field monitoring method combined with model tests, or to use the statistical method. Although these methods are very useful to get information of tunnel stability, they can only give out the final results instead of the failure process evolvement. Although model test is the main means of study on the engineering structure failure, the high cost, long periods and difficulties of parameters adjusting in the limited models have consumedly restricted its usage in the stability analysis of tunnel. Another big problem is the difficulties on simulating those disasters triggered by geological and engineering reasons in laboratory. Although many domestic and oversea scholars have done a lot of works on the stability of rock masses, the understanding of failure mechanism of rock mass, especially the progress failure of rock mass under the influence of structural planes is still far from being complete.In this paper, a numerical code called RFPA is used to study the failure and displacement mechanism of tunnel under the influence of structural planes, which is based on the understanding of heterogeneity of rock masses. The constitutive model of this code is based on the damage theory and statistical theory, which’can reflect the progress failure of rock mass vividly. Compared with the traditional loading method used in the study of tunnel stability, a new method called Strength Reduction Method (SRM) is used, by which the degradation and deformation process of rock masses caused by excavation can be closely connected with the geological formation and the tectonic stress. Numerical models that can simulate the deformation, damage and progress failure are established by considering the progress degradation of rock mass. The main contents are as follows:The SRM, which can simulate the gradually degradation phenomena of rock masses during and after excavation, is used in the stability analysis of rock tunnel. The deformation, damage and failure mechanism of tunnel under the unloading condition are analyzed and the reliability of SRM in the stability analysis is evaluated.The deformation and failure characteristics of layered roof of tunnel are analyzed and the influence of thickness of layered formation and lateral pressure coefficient on the failure mechanism is also studied. Meanwhile the failure mode and deformation characteristic of tunnel in dip layered rock mass are analyzed and the applicable condition of the geographical method given by Goodman in 1976 is discussed. The failure mechanism of the vertically stratified rock masses is also studied and the limitations of beam-board theory used nowadays are pointed out.The influence of the fault distribution and fault dip on the stability of tunnel is studied. The influence of fault thickness and tectonic stress on the failure mechanism of tunnel is discussed and an elementary method of judging the failure zone is given out.The failure mechanism of tunnel in rock masses cut by two sets of joints is analyzed. The influence of the attitude of bed of joints, the connectivity of joints and the lateral pressure coefficient on the stability and safety factor are also discussed.By using Lenovo Shenteng 1800 parallel computer, the mechanism of zonal disintegration around deep buried single and twin tunnels in layered formations are analyzed. The occurrence condition of zonal disintegration and the factors that affect it are studied.更多还原