【作者】 苏华友；

【导师】 张继春；

【作者基本信息】 西南交通大学 ， 岩土工程， 2009， 博士

【摘要】 与钻爆施工法相比,TBM法对围岩产生的扰动较小,能充分保护围岩的自身强度,有效利用围岩的自稳能力,减轻隧洞支护结构的自重,节约工程材料,并能保证隧洞施工的安全、高效、优质和环保。TBM已经广泛应用于水利水电、公路铁路、矿山及国防等行业的地下工程建设之中。但如何确保TBM在有松散性围岩、挤压性围岩、地下水发育、高地应力等复杂地质条件下的深埋长大隧洞中仍然能安全、连续、高效的施工,这是TBM施工中很关键且无法回避的现实问题,也是TBM隧洞围岩稳定性研究的热点与难点问题之一。采用微地震技术对施工中的大型水工隧洞围岩稳定性进行动态监测,试验结果表明,岩体微破裂时序特征与空间分布特性都清楚地显示出在导流洞、交通洞及勘探洞的交界区域因强应力集中而导致的岩体破裂,并发现岩体破裂程度会随着施工结束及时间推移而减小,以此推断出该交界区域岩体内应力被逐渐释放而趋于稳定的状态。与此同时还在导流洞内已有的顶板冒落区附近监测到较强的微地震事件,这些事件的时空分布有助于进一步分析该顶板动态演化的发展趋势。在此基础上,建立了以微地震事件频数与时间关系曲线的二阶导数来推测围岩稳定状态的方法,给出了微地震事件频率与传播距离的理论计算公式,提出了以微地震的空间分布、时间分布、能级变化与尺度效应等指标的综合值来判断围岩稳定的方法,并初步给出了Ⅰ、Ⅱ、Ⅲ、Ⅳ等四个级标准,为探索TBM隧洞地质微地震超前预报新方法的建立指明了方向。根据弹性力学理论及Hoek-Brown强度准则,研究了TBM开挖深埋隧洞围岩的变形特征及其力学效应问题,提出了围岩支护压力折减量（?）的新概念,给出了围岩塑性区半径、洞壁周边位移、最大支护压力等理论计算公式,并将理论计算结果与相关现场实测数据进行了分析对比,证实了理论计算公式的可靠性。在此基础上,讨论了TBM滚刀推力与岩石单轴抗压强度、岩体类型、岩体完整性等因素的关系,得出了以滚刀推力表示的洞壁位移方程,由此建立了TBM开挖与围岩性质的内在联系,对TBM施工有一定的实际指导意义。在具体分析深埋隧洞条件下松散性、挤压性围岩影响双护盾TBM施工的基础上,分别研究了聚氨酯化学灌浆的工艺流程、化学灌浆固结松散性围岩前后的数值计算模型、挤压性地层埋深与双护盾TBM卡机的关系以及挤压性围岩的数值计算模型。提出了化学灌浆固结松散性围岩合理厚度的计算方法,确定了减压支洞与主隧洞之间洞壁厚度的最佳值,从而改变了目前施工中多以经验方式确定灌浆厚度和洞壁厚度的局面,为指导双护盾TBM快速穿过不良地质地段有重要的现实意义。按支护衬砌方式的不同将双护盾TBM隧洞围岩支护分为钢体护盾支护段和管片衬砌段。在钢体护盾支护段,研究了护盾与围岩间摩擦阻力的计算方法,讨论了影响摩擦阻力大小的因素,并根据Hoek-Brown强度准则,计算了围岩在理想的弹性与塑性条件下钢体护盾所承受的围岩压力大小,解释了允许双护盾TBM有一定超挖的重要意义。在管片衬砌段,建立了四边形管片衬砌结构的梁——弹簧计算模型,研究了三种典型围岩条件下四边形管片衬砌结构的内力分布规律;将六边形管片——灌浆砼层——围岩作为三位一体结构系统,建立了相应的数值计算模型,并对一个工程实例进行了数值模拟计算,结果表明该管片的强度富裕程度为31%,说明管片的设计是过于安全,有待作进一步的优化设计。最后,应用损伤力学的基本原理,研究了灌浆砼层在受压条件下微裂纹服从Weibull分布的损伤演化方程,讨论了方程中的两个参数F₀和m的具体含义。建立了以损伤效应为基础的灌浆砼层数值计算模型,发现灌浆砼层最大主应力的理论计算值与实际测试值是相符合的,研究成果对指导灌浆砼层的设计与施工有一定的实际意义。更多还原

【Abstract】 Comparing with drill blasting method, TBM（tunnel boring machine） can have a little additional excavation and lesser disturbing for surrounding rock. TBM can sufficient protect surrounding rock itself strength, adjust and reinforce tunnel itself bearing capacity and stability, reduce the weight of lining structure, thrift the engineering material. There are remarkable characteristics of safe, high quality, efficiency and environmental for the TBM excavating method, so it has been widely used in hydropower projects, road projects, railroad projects, mine and national defense projects. But in deep tunnel around incompact, extrusion, much more groundwater and high ground-stress, how does the TBM construct with safe, continuum and high efficiency. It is one of the key question for TBM construction, and the surrounding rock stability of the tunnels during and after the construction becomes a concern. It is one of the research topics for TBM excavating tunnels.At the first time, in Jin Ping hydropower station left riverbank during the super tunnel construction, the microseismic monitoring is used for the surrounding rock stability estimating, and seismic events were recorded. The microseismic results have shown that rock fractures were developed at the intersection of the water, traffic and exploration tunnels where rock weakening between these tunnels might be developed, but after the super tunnel has be excavated the intersection would become more and more stability. Fracturing was also detected where a significant roof-fall occurred nearby. The microseismic results have provided good information for engineers to understand stress conditions in the rock mass and to assess the stability of the tunnels. Using the second derivative of the relation curve of microseismic frequency as a function of time,we may confer the surrounding rock that is stable or not. The study has also obtained the relationship between microseismicity and seismic transmission distance. At last, using the results colliqated microseismic interspace distributing, time distributing, power grade changing and scale domino offect, the tunnel surrounding rock stability can be set off four grades from stabilization to unstable estate, they are I , II, III and IV, this also is the results of tunnel microseismic prediction.Based on deformation characteristic and mechanical effect of the surrounding rock in deep tunnel by TBM excavating inland, a new concept of lining press discount coefficient for tunnel surrounding rock is presented according to elasticity mechanics principle and Hoek-Brown criterion. It is suggested some of calculating formulae for plastic radius, plastic displacement and the best lining press. The results of academic calculating were in good agreement with the site monitoring results, and it has shown that the academic calculating formulae were credible. At the same time, it is discussed the connection of TBM hob thrust for the uniaxial compressive strength, the style, the inteqrality, the airslake degree of the rock, and the displacement equation with TBM hob thrust is presented. The internal relation is set up about TBM excavating with surrounding rock quality, and it is very important for TBM constructing tunnel.The incompact surrounding rock and extrusion stratum are unfavorable geological conditions for TBM excavating, they might have huge influence to time limit for a project and cost . In order to understand their influence near the tunnel, it is suggested some of study for a craftwork flow, numerical simulation of polyurethane chemical grouting concreting incompact surrounding rock, a connection of deep extrusion stratum with TBM jamming and a mathematic mode of extrusion stratum. It is suggested a calculating formulae for the thickness of polyurethane chemical grouting, and a fine value of the decompress branch hole between the main tunnel. The theory study of the incompact surrounding rock and extrusion stratum infected the double-shield TBM constructing is very important, it has changed the old experiential method for chemical grouting concreting incompact surrounding rock and the analytical results might also channel off the double-shield TBM passing through unfavorable geological sections safely and quickly.According to different lining fashion, there are two kind of lining frames for double-shield TBM excavating tunnel, one is shield lining and the other is segment lining. In shield lining sect, the calculating method and influencing factor of frictional resistance to the shield between surrounding rock are discussed. Based on the Hoek-Brown criterion, the surrounding rock press around TBM shield is calculated in two kind of ideal state of elasticity and plastic, and explaining a little additional excavation of double-shield TBM is very importance. In segment lining sect, the beam-spring model for quadrangled segment is built, and to study internal force and deformation of the segment lining for three typical sections, which include fault fracture belt, squeezing strata and surrounding rock of class III. Following the study the structural stress zones where hexagon segment and pea gravel backfilling grouting and surrounding rock might be regarded as lining system, and the calculating results of a puoject example are shown that the richness intension of hexagon segment is 31%, so the segment is above safe intension, and it may be farther optimized.Based on principle of damage mechanics, the press damage variable of pea gravel backfilling grouting is defined. The damage evolution equations corresponding for subjection Weibull distributing is determined, and to discuss the parameter F₀ and m inside the damage evolution equations. To build the mathematic model of pea gravel backfilling grouting for damage effect, the main stress of pea gravel backfilling grouting was in good agreement with the test results.更多还原