【作者】 陈旭光；

【导师】 张强勇；

【作者基本信息】 山东大学 ， 岩土工程， 2011， 博士

【摘要】 近年来,随着国民经济的持续稳定增长,国家对地下洞室开发利用逐渐趋向于深部。在高地应力、高渗透压、高温和开挖扰动等复杂恶劣地质条件下,深部地下工程产生了诸如大变形、强流变等特殊的变形破坏方式。其中,分区破裂是最引人关注的问题。分区破裂是深部巷道围岩在高地应力下的特殊工程地质现象,如果处理不当将会造成大范围的巷道破坏。因此,国内外专家学者对此进行了大量研究,但对分区破裂的形成机制仍没有统一的结论。本文结合国家自然科学基金项目“高地应力深部巷道围岩非线性变形破坏机理及锚固特性的研究”,以淮南矿区丁集煤矿-910m深部巷道为工程背景,通过采用真三维地质力学模型试验和理论分析相结合,并辅以现场监测和数值模拟的手段,全面系统研究了高地应力条件下深部巷道围岩分区破裂形成机制以及分区破裂形成过程中围岩的变形破坏规律。以此为基础,建立了分区破裂形成的条件判据,并研究了深部巷道围岩分区破裂的锚固特性。主要的研究内容和创新点如下：1)通过钻孔电视对淮南丁集矿深部巷道进行围岩破坏观测证实,深部巷道围岩存在分区破裂现象。观测结果初步表明深部巷道围岩分区破裂的破裂形态、破裂区半径、分布特征等与开挖巷道半径密切相关。2)开展了预留洞室轴向压缩破坏的模型试验,发现轴向高压力下洞室围岩出现了多条间隔破坏线。初步表明轴向高压力是导致产生分区破裂的重要因素。3)首次通过相似材料三维地质力学模型试验,再现出高地应力条件下深部巷道开挖导致围岩形成分区破裂现象,并获得巷道围岩位移和径向应变呈现波峰与波谷交替分布的波浪形变化规律。试验得到的分区破裂形态特征及围岩位移分布规律与现场监测基本一致。4)自主研制的高地应力真三维加载模型试验系统可用于同步、独立地向模型施加三轴高地应力。5)研究得到巷道围岩裂纹的扩展轨迹。首先提出了受压裂纹扩展的计算方法,然后通过扩展有限元将其应用于裂纹扩展轨迹的计算,计算结果表明围岩裂纹扩展到一定长度将最终趋向于形成环状断裂。6)通过对深部巷道围岩应力应变场和能量场的研究,揭示了分区破裂的形成机制。即围岩弹塑性区边界存在着切向应力峰值、径向应变不协调性和应变能的聚集,使该区域形成与开挖洞室呈同心圆的环状断裂,从而导致围岩卸荷及应力重分布并使围岩产生新的弹塑性区边界。该过程不断循环、递进,便形成了分区破裂现象。揭示了分区破裂产生后围岩位移与应变呈波峰波谷波浪形分布的原因在于新的塑性区的不断形成,使得新形成的塑性区的应变和位移值出现突变。7)通过研究得到形成分区破裂的地应力特征为轴向地应力第一或第二主应力,各破裂区形成具有时间上的递进性；当地应力不足以达到判据时分区破裂过程停止；分区破裂形态与开挖洞室半径、围岩力学参数等有关,各破裂区半径之间符合等比关系。这基本解释了试验和现场观测到的现象。8)建立了分区破裂的起裂判据。首先提出了极坐标系下的滑移裂纹模型,并将其扩展到一定程度后等效为圆弧形裂纹,通过复变函数计算了其受圆形洞室影响下的应力强度因子,认为当其大于围岩断裂韧度时分区破裂开始形成。9)基于能量平衡原理建立了分区破裂的形成判据：首先通过研究认为围岩开挖卸荷释放的应变能为围岩破坏的能量来源,并计算了围岩的可释放应变能；然后通过极坐标系下滑移裂纹模型计算了环状断裂形成所耗散的能量。当围岩可释放应变能大于塑性区边界环状断裂形成所耗散的能量时,分区破裂将会形成。10)将得到的分区破裂起裂判据程序化,将其嵌入扩展有限元平台,初步经过对高应力下深部巷道的模拟,得到了围岩的分区破裂现象。模拟得到的围岩破坏形态、破裂圈数等均与试验观察到的分区破裂现象大体符合。11)通过深部巷道围岩分区破裂锚固特性的地质力学模型试验发现锚杆对分区破裂有明显抑制作用。发现轴向高地应力作用下深部巷道围岩潜在的分区间隔破裂导致锚杆受力呈现拉压交替的变化现象。12)通过研究锚杆完全屈服时所吸收的能量,建立了基于能量平衡原理的抑制分区破裂形成的判据。初步研究了抑制分区破裂现象而采取的锚杆布置方式。更多还原

【Abstract】 In recent years, with the rapid and stable development of the national economy, the utilization and developing of the underground cavern have been getting to deep embedded area. In the condition of complex geological environment such as high geo-stress, high osmotic pressure, high temperature and excavation induced disturbance, there appears special engineering response character, such as the large deformation, great rheology, etc. Among which the zonal disintegration phenomena is the most attractive problem. Specialists both home and abroad carried on much research on this, but there isn’t a uniform conclusion on the forming mechanism yet.Under the financial support of National Natural Science Foundation of China (Grant No.40772173) and taking the deep tunnel which the embedded depth is 910m in Dingji coal mine of Huainan mine area as the background, the in-situ monitoring method, the true triaxial geomechanical model test, theoretical analysis and numerical simulation method are jointed together to research the forming mechanism and anchorage characteristic under high geostress entirely. Take the theoretical analysis and engineering practice tight coupling, the work in some aspect have been finished and listed below:1) Through the in-situ monitoring, the zonal disintegration phenomena is proved to be existed, and the displacement law of wave crest and trough distributed alternately during the forming procedure which is different the shallow embedded tunnel is got. The results showed that the fracture shape of zonal disintegration are related to the radius of the excavated tunnel.2) through the model test of the axial compression on the cavern obligated, it is found that the axial high geo-stress is the important factor which lead to the zonal disintegration.3) The zonal disintegration phenomenon is first reappeared in laboratory through the geomechanical model test. And the displacement and radical strain changing law of wave crest and trough distributed alternately during the forming procedure which is different the shallow embedded tunnel is got. The fracture shape and displacement distribution law is accord with the in-situ observations.4) The self-developed high geo-stress true 3D loading model test system can be used to apply triaxial high stress synchronization and independently.5)the crack propagation trajectory in surrounding rocks are got based on research. First, the computing method of crack extension under compression is established, and then takes it into the computing of crack extension trajectory through the XFEM. The numerical result shows that the crack will intend to form the circle fracture when the crack propagates to some length.6) Through the research on the stress field and energy field of deep tunnel surrounding rocks, the forming mechanism of zonal disintegration was established, there exists the discontinuity of strain and crest value of tangential stress and energy aggregation in the elasto-plastic zone, which make the crack propagation and forming circle fracture. After the formation of the circle fracture, the surrounding rock mass will unloading, which make new stress redistribution and the new plastic zone’s forming. The process list up will repeat in the new plastic boundary and induce the forming of the zonal disintegration phenomena. The reason of changing laws of alternation of crest and wave displacement and radical strain in surrounding rocks was revealed, which is the constant formation of newly plastic zone make the strain and displacement break in the newly formed plastic zones.7) Through the research, it is found that the geo-stress character of zonal disintegration forming is that the axial geo-stress is the first or second principal stress, and the fractured zones formed one by one. When the geo-stress is not enough to the criterion, the zonal disintegration formation will stop. The fractured shape of zonal disintegration is related to the radius of excavated cavern and mechanical parameters of surrounding rocks, and the radius of all fractured zones are equal ratio, which explains the phenomenon observed in test and in-situ monitoring.8) The initiation criterion of zonal disintegration is established. Fist, the sliding crack model in polar coordinates system is established, and when propagate to some length it is equivalent to the circle crack. The stress intensity factor is computed through the complex variables functions, and the zonal disintegration start to form when it is larger than the fracture toughness.9) The forming criteria of zonal disintegration are established based on the energy balance theory:first, the strain energy released through excavation and unloading is regarded as the energy resources of surrounding rocks damage, and the releasable strain energy was computed. Then, Take it to compare with the energy dissipatation during the formation of the circle fracture, the energy criteria of zonal disintegration is got.10) Make the zonal disintegration initiation criteria programmed and implant it into XFEM platform of Abaqus, the zonal disintegration phenomena is simulated. The fracture shape and fracture zones of zonal disintegration got from simulation are fit with the zonal disintegration phenomenon observed in test.11) Through the geomechanical model test of anchorage character of deep tunnel rock mass, the suppress impact of anchor on the zonal disintegration was found. The compression-tension alternation phenomena in rock bolt is got, which reflects that there exists the trend of forming zonal disintegration in deep rock mass.12) through the research on the energy of the anchorage can absorbed when it is entirely yield, the criteria of suppress the zonal disintegration based on the energy balance theory is got. The rock bolts arrange pattern to suppress the zonal disintegration phenomenon is researched preliminary.更多还原