地下结构承载围岩自稳能力量化方法及支护优化研究

发布时间：2018-04-26 20:00

本文选题：围岩自稳能力 + 强度折减法　；参考：《湖南大学》2015年硕士论文

【摘要】：现代地下结构支护原理认为围岩既是产生山岩压力的来源,更是承载的主体,人工支护起辅助承载作用。但据此发展而来的行业规范仅给出各级围岩支护的定性描述,其具体支护类型及参数则依赖决策人员的工程经验类比确定,造成了材料的不必要浪费。因此,为使支护设计向定量化方向发展,本文以围岩自稳能力为研究对象,开展了如下几方面的研究:首先,论述强度折减数值分析方法在岩土工程稳定性计算中的应用,并对有限差分软件FLAC的工作原理及其优缺点做简要介绍,继而借助增量弹性理论和既定流动法则对剪破坏和拉破坏情况下的M-C塑性应力修正值做差分形式推导。然后,引入运动平衡的概念将围岩自稳状态划分为稳定平衡状态和非稳定平衡状态两种,同时提出以塑性区和关键点位移变化特征为据,分段拟合围岩弹塑性变形和塑性流动阶段曲线方程,联立求解以锁定围岩临界破坏特征点的方法。之后,依托大量规范辨识出围岩强度恰能承受住所有破坏力作用的极限状态,并运用FLAC3D和强度折减思想求此状态下围岩稳定系数k0,以k0作为恒稳判别的定量标准,然后通过大量数值模拟辨识出II~IV级围岩保持长久稳定的条件,初步量化了其围岩自承载结构在维持硐室稳定中所起作用。再有,先对满足隧洞工程建筑内限要求的等面积四大断面形式做稳定性计算,对k0进行修正;再采用不同泊松比和弹性模量对某隧洞围岩进行强度弱化模拟,发现泊松比和弹模对稳定系数影响极小,进而克服了传统塑性区判据和位移判据因此二者测量不准而判定不一的缺陷;紧接着开展室内相似模型试验,所得结果与数值模拟结果相互印证,从而验证恒稳系数k0的正确性。其次,分析不同支护类型的力学特性和作用机理,并结合勘察资料和公路隧道设计规范,运用本文方法给出广西蒙沙隧道(1)标段III级围岩的支护优化方案。最后,针对现有锚杆延伸率低、不能适应巷道围岩大变形需要的问题,发明设计了一种新型增阻让压构件,并开展了相关工作。
[Abstract]:The principle of modern underground structure support holds that the surrounding rock is not only the source of mountain rock pressure, but also the main body of bearing capacity, and artificial support plays an auxiliary role in carrying capacity. But the industry standard developed according to this only gives the qualitative description of surrounding rock support at all levels, and its concrete support types and parameters depend on the engineering experience analogy of the decision makers, resulting in unnecessary waste of materials. Therefore, in order to make the support design develop to the quantitative direction, this paper takes the self-stability ability of surrounding rock as the research object, carries out the following research: first, discusses the application of the strength reduction numerical analysis method in the geotechnical engineering stability calculation. The working principle, advantages and disadvantages of finite difference software FLAC are briefly introduced, and then the modified values of M-C plastic stress under shear failure and tensile failure are derived by means of incremental elasticity theory and established flow rule. Then, the concept of motion equilibrium is introduced to divide the self-stability state of surrounding rock into two kinds: stable equilibrium state and non-stable equilibrium state. At the same time, the characteristics of displacement change in plastic zone and key point are proposed as the basis. The phase curve equation of elastoplastic deformation and plastic flow of surrounding rock is fitted in sections, and the method of locking the critical failure characteristic point of surrounding rock is solved simultaneously. After that, based on a large number of codes, the strength of surrounding rock can be identified as the limit state of the destructive effect of residence, and the stability coefficient of surrounding rock under this condition is obtained by using FLAC3D and strength reduction thought, and K0 is taken as the quantitative criterion for the determination of constant stability. Then, the conditions for the II~IV class rock to maintain long-term stability are identified by a large number of numerical simulations, and the role of the surrounding rock self-bearing structure in maintaining the stability of the chamber is preliminarily quantified. Secondly, the stability of four sections with equal area to meet the requirements of the inner limit of tunnel construction is calculated, and k0 is modified, and then the strength of surrounding rock of a tunnel is simulated by using different Poisson's ratio and elastic modulus. It is found that Poisson's ratio and modulus of elasticity have minimal influence on the stability coefficient, which overcomes the defects of traditional plastic zone criterion and displacement criterion. The results obtained are consistent with those of the numerical simulation, which verifies the correctness of the constant stability coefficient k _ 0. Secondly, the mechanical characteristics and action mechanism of different supporting types are analyzed. Combined with the survey data and the design code of highway tunnel, the support optimization scheme of III grade surrounding rock in the section of Mengsha tunnel in Guangxi is given by using the method of this paper. Finally, in order to solve the problem of low elongation of existing bolt, which can not adapt to the need of large deformation of surrounding rock of roadway, a new type of resistance and pressure increasing component is designed and related work is carried out.
【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】：TU45

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