大跨度扁平隧道围岩松动圈影响因素及理论计算研究

发布时间：2018-02-02 03:55

本文关键词： Hoek-Brown准则围岩松动圈二次正交组合试验可拓理论扰动参数D　出处：《湖南科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：隧道开挖后，，初次喷层和二衬衬砌的厚度视围岩而定，实际施工中往往具有保守性。如何更为精准的确定支护衬砌厚度，可明显节约资源，减少施工时间，加快施工进度。松动圈理论认为可由围岩松动圈的厚度值确定隧道支护参数。近些年，学者们所得到松动圈厚度值均为经验或近似公式，研究过程所考虑的因素为隧道的地应力、埋深和岩体强度等，而没有考虑围岩卸荷扰动后岩体的节理风化情况、节理间距、以及爆破损伤等情况。围岩松动圈厚度值可根据Hoek-Brown强度准则推导，但Hoek-Brown强度准则中对地质强度指标GSI和扰动参数D的选取没有明确参考资料，工程实际中选取模糊。本文结合理论分析、现场测试等多种手段，讨论了施工扰动对岩体的影响以及在实际工程中应如何考虑，提出了基于可拓理论的扰动参数D的取值方法，并将改进后扰动参数应用于松动圈理论计算。本文主要研究内容如下： (1)基于二次正交试验法对围岩松动圈的影响因素进行了分析。围岩松动圈的形成实质是松动圈内围岩产生碎胀变形，碎胀变形是围岩卸荷扰动产生的松动与破坏，其影响因素包括地下水、地应力、以及其它地质力学指标如霍克布朗参数等。本文采用二次正交组合试验的4因素5水平试验方案，并结合地质雷达，按照组合设计表进行了17次野外试验。经过计算分析得出影响因素的显著性由高至低分别为：霍克布朗参数S、霍克布朗参数M、霍克布朗参数S和霍克布朗参数M的交互作用、隧道埋深。 (2)为了更真实地反映岩体的扰动程度，既考虑工程岩体中围岩级别和爆破因素对松动圈的扰动影响，也结合《工程岩体分级标准》中的岩体完整性指标Kv和超声波探测技术来确定扰动参数D。根据围岩的实际扰动特点，基于可拓学理论，建立了Hoek-Brown准则扰动参数D的物元模型，并引入熵权法分析了扰动指标的权重。 (3) Hoek-Brown准则对于扰动参数D的参考取值具有模糊性和离散性，基于可拓原理，在物元模型的理论基础上，综合考虑爆破损伤、卸荷情况、结构面发育程度和围岩级别四个扰动程度影响因子，确定了扰动参数D的取值参考范围，为考虑岩体扰动程度的参考提供有效依据。 (4)运用改进的岩体扰动参数D，结合隧道围岩的其他参数，计算得到隧道围岩的松动圈理论厚度值，并应用声波测试对隧道的松动圈厚度值进行了测试，并与理论值进行了对比。结果表明：以物元模型为基础所改进的扰动参数D所计算得到的松动圈理论值与实测值基本一致，验证了理论解的可靠性。
[Abstract]:After the tunnel excavation, the thickness of the first jetting layer and the second liner lining depends on the surrounding rock, and it is often conservative in the actual construction. How to determine the thickness of the supporting lining more accurately, can obviously save resources and reduce the construction time. In recent years, the loosening circle thickness obtained by scholars are all empirical or approximate formulas. The factors taken into account in the study are the ground stress, buried depth and rock mass strength of the tunnel, but the joint weathering, joint spacing and blasting damage of the rock mass after unloading and disturbance of surrounding rock are not taken into account. The thickness of loosening zone of surrounding rock can be deduced according to Hoek-Brown strength criterion. However, there is no clear reference for the selection of geological intensity index GSI and disturbance parameter D in Hoek-Brown strength criterion, and the selection is fuzzy in engineering practice. In this paper, the influence of construction disturbance on rock mass and how to consider it in practical engineering are discussed, and the method of determining disturbance parameter D based on extension theory is put forward. The improved disturbance parameters are applied to the calculation of loosening circle theory. The main contents of this paper are as follows: 1) based on the quadratic orthogonal test, the influencing factors of the loosening zone of surrounding rock are analyzed. The essence of the formation of the loosening circle of surrounding rock is that the surrounding rock in the loosening zone produces dilatation and deformation. Dilatation deformation is the loosening and destruction of surrounding rock caused by unloading disturbance, and its influencing factors include groundwater and in-situ stress. And other geomechanical indexes, such as HawkBrown parameter, etc. In this paper, we adopt four factors and five levels test scheme of quadratic orthogonal combination test, and combine with ground penetrating radar. According to the combined design table, 17 field tests were carried out. The results showed that the significance of the influencing factors from high to low were: HawkBrown parameter Sand HawkBrownian parameter M. The interaction between the HawkBrownian parameter S and the HawkBrownian parameter M is the depth of the tunnel. 2) in order to reflect the disturbance degree of rock mass more truthfully, the influence of rock mass level and blasting factors on the disturbance of loosening zone is considered. The disturbance parameter D is determined by using the integrality index Kv of engineering rock mass classification standard and ultrasonic detection technology. According to the actual disturbance characteristics of surrounding rock mass, the extension theory is used. The matter-element model of disturbance parameter D of Hoek-Brown criterion is established, and the weight of disturbance index is analyzed by entropy weight method. The Hoek-Brown criterion is fuzzy and discrete to the reference value of disturbance parameter D. Based on the extension principle and the theory of matter-element model, blasting damage is considered synthetically. The unloading condition, the development degree of structure plane and the disturbance degree of surrounding rock are four influencing factors, and the reference range of disturbance parameter D is determined, which provides an effective basis for considering the disturbance degree of rock mass. 4) using the improved rock disturbance parameter Dand other parameters of tunnel surrounding rock, the theoretical thickness of loosening circle of tunnel surrounding rock is calculated, and the thickness of loosening circle of tunnel is tested by acoustic wave test. The results show that the theoretical values calculated by the improved disturbance parameter D based on the matter-element model are in good agreement with the measured values, and the reliability of the theoretical solution is verified.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451.2

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