非圆形地下洞室围岩收敛曲线近似构建方法研究

发布时间：2018-06-06 05:07

本文选题：非圆形洞室 + 等代圆　；参考：《湖南大学》2015年硕士论文

【摘要】：随着人口不断增加、国家经济和国防建设的快速发展,地下空间的开发利用逐步展开,人们在地层中开挖各种形状和尺寸的地下洞室、隧道和巷道等,而地下洞室开挖后其周边围岩的弹塑性应力和位移分布对于后期围岩支护结构的设计、施工以及洞室围岩稳定性分析有着重要影响。因此,用来表征地下洞室开挖后围岩应力和位移关系的弹塑性围岩收敛曲线(Ground Response Curve简称GRC)的研究成为地下洞室围岩稳定性分析的重要环节。限于当前弹塑性力学发展水平,目前仅圆形洞室具有完整的围岩收敛曲线解析形式,非圆形洞室需要通过复杂的数值方法拟合。为提高非圆形洞室计算效率,拓展解析法的适用范围,有利于收敛-约束法在非圆形地下洞室支护设计中的应用,本文基于等代圆理论探讨了非圆形洞室近似解析围岩收敛曲线(GRC)的构建方法。首先,分别推演了不考虑塑性扩容的Karstner弹塑性围岩收敛曲线和Duncan-Fama弹塑性围岩收敛曲线的建立过程,并对现有的等代圆理论作了详细的归纳分析。其次,以直墙拱形洞室为例,采用数值方法求得非圆形洞室开挖后在不同支护阻力作用下洞周围岩的弹塑性应力和位移并绘制相应的围岩收敛曲线,与在相同的初始条件下基于各种等代圆方法建立的近似围岩收敛曲线(GRC)解析解做对比分析,揭示各等代圆方法的适用性。然后,按照研究直墙拱形洞室的方法,分别分析矩形和曲墙拱形洞室在求解近似围岩收敛曲线时最适用的等代圆方法,并分析跨高比、围岩级别及洞室埋深等因素对等代圆方法选用的影响。最后,引用工程实例对前文得出的结论进行分析验证,并开展非圆形洞室的模型试验研究,监测矩形洞室开挖后洞周围岩应力和位移,绘制相应围岩收敛曲线,与用本文方法求解得到的矩形洞室近似围岩收敛曲线(GRC)做对比分析,进一步验证了本文方法的有效性和实用性。
[Abstract]:With the increasing population, the rapid development of national economy and national defense, the development and utilization of underground space, people excavate underground caverns, tunnels and roadways of various shapes and sizes in the stratum. The elastic-plastic stress and displacement distribution of surrounding rock around underground cavern after excavation has important influence on the design, construction and stability analysis of surrounding rock. Therefore, the study of the elastoplastic surrounding rock convergence curve ground Response Curve, which is used to characterize the stress and displacement of surrounding rock after excavation, has become an important link in the stability analysis of underground cavern surrounding rock. Limited to the development level of elastoplastic mechanics at present only the circular cavern has a complete analytical form of surrounding rock convergence curve and the non-circular cavern needs to be fitted by complex numerical method. In order to improve the calculation efficiency of the non-circular cavern and expand the scope of application of the analytic method, it is beneficial to the application of the convergency-constraint method in the support design of the non-circular underground cavern. In this paper, based on the theory of equivalent circle, the construction method of approximate analytic wall rock convergence curve (GRCC) of non-circular cavern is discussed. Firstly, the convergence curve of Karstner elastoplastic surrounding rock and the convergent curve of Duncan-Fama elastoplastic surrounding rock without plastic expansion are derived, and the existing equivalent circle theory is summarized and analyzed in detail. Secondly, taking the arched cavern of straight wall as an example, the elastoplastic stress and displacement of surrounding rock around the cavern after excavation of non-circular cavern after excavation are obtained by numerical method, and the corresponding convergence curves of surrounding rock are drawn. The results are compared with the analytical solution of the approximate wall rock convergence curve (GRCC) based on various equivalent circular methods under the same initial conditions, and the applicability of each method is revealed. Then, according to the method of studying the arched cavern of straight wall, the most suitable equivalent circle method for solving the approximate wall rock convergence curve and the ratio of span to height are analyzed, respectively, for rectangular and curved wall arched caverns. Influence of factors such as surrounding rock level and buried depth of cavern on the selection of equivalent circle method. Finally, an engineering example is cited to analyze and verify the above conclusions, and the model test of the non-circular cavern is carried out to monitor the stress and displacement of the surrounding rock around the tunnel after the excavation of the rectangular cavern, and draw the corresponding surrounding rock convergence curve. Compared with the approximate wall rock convergence curve of rectangular cavern obtained by the method in this paper, the validity and practicability of this method are further verified.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU457

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