浅埋偏压大跨度隧道风险评估与围岩稳定性研究
发布时间：2018-09-09 16:54
【摘要】：浅埋隧道的围岩松散破碎，节理裂隙发育，使得围岩容易发生失稳破坏，开挖过程中常出现冒顶、塌方、突水等不良灾害；隧道偏压效应使得衬砌结构受力失衡，引起初期支护和二次衬砌的开裂，降低隧道结构的承载能力并破坏防排水系统，导致在运营过程中可能出现渗水等不良病害；而隧道开挖宽度的增大更加剧了围岩与衬砌结构的不稳定性。因此浅埋偏压大跨度隧道的围岩稳定分析与施工风险评估成为亟需解决的问题。 以广深沿江高速宴岗隧道为工程背景，对不同净距的浅埋偏压隧道进行了数值模拟；采用模糊层次分析法与基于可拓理论的评估物元模型，对浅埋偏压大跨度隧道进行了风险评估；并采用地质统计学中的克里格法对大跨度隧道的围岩稳定性进行了可靠度分析。本文主要取得了如下成果： （1）研究了浅埋偏压大跨度隧道的力学特征与破坏模式，并通过FLAC3D软件，分析了不同因素对隧道稳定性的影响。结果表明:由于偏压效应，隧道埋深大处的塑性区明显多于其他区域。当隧道偏压率分别为1.09、1.13和1.22时，埋深大处的右边墙或右拱腰的塑性区随着偏压率增大而增加，，偏压值为1.22时，塑性区范围达到最大。 （2）利用模糊层次分析法，对浅埋偏压大跨度隧道进行了风险评估研究。在此基础上，进一步确定了浅埋偏压大跨度隧道8个风险因素集：偏压率、地质情况、含水状况、浅埋大小、岩体完整性系数、岩层产状、层面与层间裂隙以及围岩级别。基于可拓学的基本物元原理，构建了浅埋偏压大跨度隧道风险的八指标可拓风险评估物元模型，通过对定性指标的定量化以及归一化预处理，使得评估指标具有可比性。 （3）利用克里格算法中不同的变异函数对随机变量特征进行表达，结合二次正交组合法，对隧道衬砌结构的可靠度分析方法进行了研究。在计算过程中，为克服计算过程中隧道力学参数的难以确定性，提出了基于超前地质预报的参数获取方法。最后通过采用克里格法与传统蒙特卡洛方法的对比，证明了本文方法的合理性。
[Abstract]:The surrounding rock of shallow buried tunnel is loosely broken, joints and cracks are developed, the surrounding rock is prone to instability and destruction, and some bad disasters, such as roof fall, collapse, water inrush and so on, often occur in the excavation process, and the tunnel bias effect makes the lining structure unbalance in force. It causes the cracking of initial support and secondary lining, reduces the bearing capacity of tunnel structure and destroys the waterproof and drainage system, which may lead to some bad diseases such as water seepage in the operation process. The instability of surrounding rock and lining structure is aggravated by the increase of tunnel excavation width. Therefore, the analysis of surrounding rock stability and construction risk assessment of long span tunnel with shallow-buried bias pressure becomes an urgent problem to be solved. Taking the Yangang tunnel along the Yangtze River as the engineering background, numerical simulation of shallow buried bias tunnel with different net distances is carried out, and the matter element model based on fuzzy analytic hierarchy process and extension theory is used to evaluate the tunnel. The risk assessment of long-span tunnel with shallow buried bias voltage is carried out, and the reliability of surrounding rock stability of long-span tunnel is analyzed by using the Kriging method in geostatistics. The main achievements of this paper are as follows: (1) the mechanical characteristics and failure mode of long span tunnel with shallow bias voltage are studied, and the influence of different factors on tunnel stability is analyzed by FLAC3D software. The results show that the plastic zone in the deep tunnel is more than that in other regions because of the bias effect. When the bias ratio of tunnel is 1.09 ~ 1.13 and 1.22 respectively, the plastic zone of the right wall or right arched waist increases with the increase of bias rate. When the bias voltage is 1.22, the range of plastic zone reaches the maximum. (2) Fuzzy Analytic hierarchy process (AHP) is used. The risk assessment of long span tunnel with shallow bias voltage is studied. On this basis, eight risk factor sets are further determined: bias rate, geological condition, water state, shallow buried size, rock mass integrity coefficient, rock formation, plane and interlayer fracture and surrounding rock level. Based on the matter-element principle of extenics, a matter-element model of eight indexes extension risk assessment for long span tunnel with shallow bias voltage is constructed. The qualitative index is quantified and normalized pretreatment is used. The evaluation indexes are comparable. (3) the reliability analysis method of tunnel lining structure is studied by using different variation functions of Kriging algorithm to express the characteristics of random variables and combining the quadratic orthogonal combination method. In order to overcome the uncertainty of tunnel mechanical parameters in the course of calculation, a parameter acquisition method based on advanced geological prediction is proposed. Finally, the rationality of this method is proved by comparing the Kriging method with the traditional Monte Carlo method.
【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;U455
本文编号：2233009
[Abstract]:The surrounding rock of shallow buried tunnel is loosely broken, joints and cracks are developed, the surrounding rock is prone to instability and destruction, and some bad disasters, such as roof fall, collapse, water inrush and so on, often occur in the excavation process, and the tunnel bias effect makes the lining structure unbalance in force. It causes the cracking of initial support and secondary lining, reduces the bearing capacity of tunnel structure and destroys the waterproof and drainage system, which may lead to some bad diseases such as water seepage in the operation process. The instability of surrounding rock and lining structure is aggravated by the increase of tunnel excavation width. Therefore, the analysis of surrounding rock stability and construction risk assessment of long span tunnel with shallow-buried bias pressure becomes an urgent problem to be solved. Taking the Yangang tunnel along the Yangtze River as the engineering background, numerical simulation of shallow buried bias tunnel with different net distances is carried out, and the matter element model based on fuzzy analytic hierarchy process and extension theory is used to evaluate the tunnel. The risk assessment of long-span tunnel with shallow buried bias voltage is carried out, and the reliability of surrounding rock stability of long-span tunnel is analyzed by using the Kriging method in geostatistics. The main achievements of this paper are as follows: (1) the mechanical characteristics and failure mode of long span tunnel with shallow bias voltage are studied, and the influence of different factors on tunnel stability is analyzed by FLAC3D software. The results show that the plastic zone in the deep tunnel is more than that in other regions because of the bias effect. When the bias ratio of tunnel is 1.09 ~ 1.13 and 1.22 respectively, the plastic zone of the right wall or right arched waist increases with the increase of bias rate. When the bias voltage is 1.22, the range of plastic zone reaches the maximum. (2) Fuzzy Analytic hierarchy process (AHP) is used. The risk assessment of long span tunnel with shallow bias voltage is studied. On this basis, eight risk factor sets are further determined: bias rate, geological condition, water state, shallow buried size, rock mass integrity coefficient, rock formation, plane and interlayer fracture and surrounding rock level. Based on the matter-element principle of extenics, a matter-element model of eight indexes extension risk assessment for long span tunnel with shallow bias voltage is constructed. The qualitative index is quantified and normalized pretreatment is used. The evaluation indexes are comparable. (3) the reliability analysis method of tunnel lining structure is studied by using different variation functions of Kriging algorithm to express the characteristics of random variables and combining the quadratic orthogonal combination method. In order to overcome the uncertainty of tunnel mechanical parameters in the course of calculation, a parameter acquisition method based on advanced geological prediction is proposed. Finally, the rationality of this method is proved by comparing the Kriging method with the traditional Monte Carlo method.
【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;U455
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