衬砌背后空洞对隧道围岩压力分布规律的影响研究

发布时间：2018-06-27 00:12

本文选题：衬砌背后空洞 + 围岩压力分布　；参考：《北京交通大学》2014年硕士论文

【摘要】：摘要：随着隧道运营数量的不断增加,运营时间的不断增长,已有大量的隧道出现了不同程度的病害现象,如衬砌变形、裂损、道床损坏、结构渗漏水等,严重威胁着隧道内的行车安全。造成隧道出现病害的原因有很多,其中,衬砌背后存在空洞是主要原因之一。衬砌背后存在空洞改变了衬砌与围岩的相互作用关系,恶化了衬砌的受力状态,造成了衬砌病害的产生。准确的确定衬砌的受力状态对隧道病害的预防及治理具有重要的意义。为明确空洞存在下衬砌的受力状态,本文采用数值模拟的方法对衬砌背后存在空洞时围岩压力分布规律、诸如隧道埋深、围岩级别等因素对围岩压力分布的影响规律及空洞存在时衬砌安全系数计算的模型等进行了研究,得出以下主要研究结论： (1)衬砌背后存在空洞,改变了荷载的传递路径,改变了围岩压力的分布规律,在空洞两侧形成了围岩压力增大区和围岩压力减小区。 (2)定义了压应力平均增大系数及压应力增大范围两个参数来表征围岩压力增大区的特征,得出压应力平均增大系数随围岩级别、隧道埋深及衬砌厚度的增加,而呈逐渐减小的趋势,随开挖范围及释放系数的增加而呈逐渐增大的趋势；压应力增大范围随空洞范围、围岩级别、隧道埋深及衬砌厚度的增大而呈逐渐增大的趋势,随释放系数的增大呈逐渐减小的趋势。 (3)对于空洞组合而言,当空洞范围较小,空洞相距较远时,空洞群之间叠加效应较小,围岩压力分布及衬砌变形规律与单空洞相同；当空洞范围较大或相距较近时,两空洞间存在叠加区域,会改变叠加区域内的围岩压力分布,降低叠加区域内衬砌的安全系数。 (4)基于以上所得规律,提出了考虑空洞两侧围岩压力增大区影响的荷载-结构模型中的荷载加载模式,并通过算例对比分析了考虑与不考虑围岩压力增大区两种情况下衬砌的安全性,计算结果表明考虑围岩压力增大区的影响时,衬砌安全系数普遍降低,最危险位置由空洞中心向空洞两侧转移。
[Abstract]:Absrtact: with the increase of tunnel operation quantity and operation time, a large number of tunnel diseases have appeared in different degrees, such as lining deformation, crack, road bed damage, structural leakage and so on. It is a serious threat to the traffic safety in the tunnel. There are many causes of tunnel disease, among which, the hole behind the lining is one of the main reasons. The existence of cavity behind the lining changes the interaction between the lining and the surrounding rock, worsens the stress state of the lining, and causes the lining disease. It is of great significance to accurately determine the stress state of lining for the prevention and treatment of tunnel diseases. In order to make clear the stress state of lining under the existence of cavities, this paper uses numerical simulation method to analyze the pressure distribution law of surrounding rock when the cavity exists behind the lining, such as the depth of tunnel burying. The influence of surrounding rock grade and other factors on the pressure distribution of surrounding rock and the model for calculating the safety factor of lining are studied. The main conclusions are as follows: (1) there are voids behind the lining. The load transfer path is changed, and the distribution of surrounding rock pressure is changed. Surrounding rock pressure increasing zone and surrounding rock pressure decreasing zone are formed on both sides of the cavity. (2) two parameters are defined to characterize the characteristics of the surrounding rock pressure increasing area, namely, the average increase coefficient of the compressive stress and the range of the compressive stress increase. The results show that the average increase coefficient of compressive stress increases gradually with the increase of surrounding rock level, the depth of tunnel and the thickness of lining, and increases with the increase of excavation scope and release coefficient, and the range of compressive stress increases with the cavity range. The surrounding rock level, the depth of tunnel and the thickness of lining increase gradually, and decrease with the increase of release coefficient. (3) for cavity combination, when the cavity range is small and the cavity is far away, The distribution of surrounding rock pressure and the deformation of lining are the same as that of single cavities, and when the voids are large or close to each other, there is a superposition area between the two voids, which will change the pressure distribution of surrounding rock in the superimposed area. (4) based on the above law, the load-loading mode in the load-structure model considering the influence of surrounding rock pressure on both sides of the cavity is proposed. The safety of lining is analyzed with and without considering the increase of surrounding rock pressure. The calculation results show that the safety factor of lining decreases when considering the influence of surrounding rock pressure increasing zone. The most dangerous position shifts from the center of the cavity to the side of the cavity.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451.2

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