深埋大跨度地下工程稳定性研究

发布时间：2018-06-02 18:12

本文选题：大跨度地下工程 + 脆-延-塑性本构模型　；参考：《北京交通大学》2016年博士论文

【摘要】：随着我国经济飞速发展,大跨度地下工程在水利水电、交通、能源储备、军事等行业中不断得到应用,目前我国最大跨度地下工程已经突破五十米。我国是大跨度地下工程建设的大国,但大跨度地下工程设计还处于经验探索阶段,而对于埋深大、跨度大、复杂工程地质条件下的地下工程的稳定性问题,是现有地下工程设计理论急需解决的难题。因此本论文以超大跨度地下工程围岩稳定性为研究对象,采用室内实验、现场监测、数值模拟等方法,对大跨度地下工程稳定性问题进行了系统研究。具体的研究方法和得到的主要结论如下所述：(1)通过对硬质砂岩的单轴及三轴试验,研究了硬质砂岩所具有弹-脆-塑性变形与破坏特征。室内试验主要进行了单轴压缩、三轴压缩、三轴循环加卸载及真三轴试验。研究了深埋条件下岩质砂岩的应力-应变特性及破坏特征,在低围压条件砂岩在达到峰值强度前的应力-应变关系接近线性,在峰后应力跌落明显,当围压超过临界压力时,峰值后的砂岩表现出较明显的延性特征。(2)建立了能反映硬质砂岩变形破坏特性的脆-延-塑转换本构模型,并根据FLAC3D软件fish语言编程规则,编制了脆-延-塑转换本构内置模型。通过数值模拟验证,利用该模型的计算成果与岩石力学性质较一致,当处于低围岩时,岩样呈现较为显著的脆性特征,随围压增加延性性质得到逐步体现,当围压处于临界围压时,岩样力学性质表现为典型的理想弹塑性状态。(3)建立利用连续介质力学进行围岩损伤区预测的研究方法。利用现场波速测试成果,通过损伤深度反分析的方法,确定了连续介质力学方法计算中的围岩参数；通过Flac3d有限差分计算软件,监测开挖过程中最大主应力随最小主应力降低的变化规律,并根据岩体的峰值强度和残余强度值,判断监测点的岩体强度状态,从而进行损伤区深度分析。(4)应用粒子流数值分析方法,确定损伤区深度随埋深、跨度的变化规律。粒子流数值分析方法可对硬质砂岩的脆-延-塑转换和破裂行为两个方面的特性进行描述,在进行大量的参数拟合的基础上,利用PFC软件对不同埋深、跨度的地下工程的损伤区进行分析,研究发现随着埋深和跨度的逐步加大,损伤区深度逐渐加深。(5)建立了多种因素对损伤区深度影响度的正交实验分析。通过对围岩级别、跨度、水平地应力系数、埋深、地应力与轴线夹角五种影响因素在五种水平下的数理统计分析,认为围岩级别和跨度对损伤区深度具有显著影响,而水平地应力系数、埋深和地应力方位角对结果没有显著影响。(6)建立了围岩稳定和支护结构可靠性的评判方法。建立了基于应力型破坏准则、变形破坏准则和块体失稳准则的大跨度地下工程的稳定性判定方法。从理论分析、数值模拟和经验类比三个途径有效判断大跨度地下工程支护结构的合理性,形成一套综合大跨度洞室支护结构稳定性判定方法。(7)在单轴、三轴岩石力学及流变试验的基础上,基于粒子群(PSO)围岩流变参数优化分析得到流变模型与试验流变曲线相吻合,该方法对于优化流变参数、提高数值模拟的准确性具有较重要意义。根据数值分析,围岩蠕变性质并未改变锚杆和衬砌受力的总体分布特征,锚杆的轴力随时间逐渐增大及安全性降低,衬砌的最大、最小压应力随时间的也呈逐渐放大趋势,但总体处于结构安全范围。
[Abstract]:With the rapid development of China's economy, the long-span underground engineering has been used in water conservancy and hydropower, transportation, energy reserve, military and other industries. At present, the largest span underground project in our country has exceeded fifty meters. China is a big country in the construction of large span underground engineering, but the design of large span underground engineering is still in the stage of experience and exploration. The stability of underground engineering under the condition of large span and complex engineering geology is an urgent problem for the existing underground engineering design theory. Therefore, in this paper, the stability of the surrounding rock of the super large span underground engineering is taken as the research object, and the stability of the large span underground engineering is solved by the methods of indoor experiment, field monitoring and numerical simulation. The main conclusions are as follows: (1) through the uniaxial and three axis tests of hard sandstone, the characteristics of the elastic brittle plastic deformation and failure of hard sandstone have been studied. The laboratory tests mainly carried out the uniaxial compression, the three axis compression, the three axis cyclic loading and unloading and the true three axis test. Stress strain characteristics and failure characteristics of rock sandstone under deep buried conditions, the stress strain relation of sandstone before the peak strength is close to linear in low confining pressure condition, and the stress drops obviously after the peak. When the confining pressure exceeds the critical pressure, the sandstone after the peak value shows obvious ductility characteristics. (2) it can reflect the deformation of hard sandstone. The brittle ductile transition constitutive model of failure characteristics is developed and the embrittlement plastic transformation constitutive model is developed according to the programming rules of the FLAC3D software fish language. Through numerical simulation, it is proved that the results of the model are in good agreement with the mechanical properties of the rock. When the rock is in low surrounding rock, the rock sample has more significant brittle characteristics and increases with the confining pressure. The properties of ductility are gradually embodied. When the confining pressure is in the critical confining pressure, the mechanical properties of rock samples are typical ideal elastoplastic state. (3) a method for predicting the damage zone of surrounding rock by continuous medium mechanics is established. The continuous medium mechanics method is determined by the method of the field wave velocity test and the method of the depth back analysis of the damage depth. The parameters of surrounding rock in the calculation are calculated. Through the Flac3d finite difference calculation software, the variation law of the maximum principal stress with the minimum principal stress is monitored in the excavation process, and the rock mass strength state of the monitoring point is judged according to the peak strength and the residual strength value of the rock mass, and the depth analysis of the damage zone is carried out. (4) the numerical analysis method of particle flow is applied. The characteristics of the two aspects of the brittle ductile transition and fracture behavior of hard sandstone can be described by the method of particle flow numerical analysis. On the basis of a large number of parameters fitting, the damage zone of different buried and span underground works is analyzed by PFC software. With the gradual increase of depth and span, the depth of the damaged area is deepened gradually. (5) the orthogonal experimental analysis of the influence degree of various factors on the depth of the damage zone is established. Through the statistical analysis of the five influence factors of the surrounding rock grade, span, horizontal stress coefficient, buried depth, and the angle between the earth stress and the axis angle, it is considered that the grade of the surrounding rock and the level of the surrounding rock are considered. The span has a significant influence on the depth of the damage zone, while the horizontal stress coefficient, the depth of the buried and the azimuth of the ground stress have no significant influence on the results. (6) the stability of the surrounding rock and the reliability of the supporting structure are established. The stability of the large span underground engineering based on the stress type failure criterion, the deformation failure criterion and the block instability criterion is established. Judging method. From three ways of theoretical analysis, numerical simulation and empirical analogy, the rationality of the support structure of large span underground engineering is judged effectively, and a set of comprehensive determination method for the stability of large span cavern supporting structure is formed. (7) on the basis of the uniaxial and three axis rock mechanics and rheological tests, the optimization of the rheological parameters of the surrounding rock mass (PSO) is based on the optimization of the rheological parameters of the surrounding rock. The rheological model is consistent with the experimental rheology curve. This method is of great significance for optimizing the rheological parameters and improving the accuracy of the numerical simulation. According to the numerical analysis, the creep property of the surrounding rock does not change the overall distribution characteristics of the stress of the bolt and lining, and the axial force of the bolt increases with time and the safety is reduced, and the most important of the lining is the lining. The maximum and minimum compressive stress increases gradually with time, but it is generally in the structural safety range.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU94;TU45

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