降雨入渗条件下膨胀土隧道力学响应分析

发布时间：2018-03-19 08:47

本文选题：膨胀土　切入点：隧道　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：膨胀土具有明显的胀缩性、裂隙性、超固结性等特殊力学特性,无论在隧道施工中或建成后都给工程带来许多难题。目前,我国对膨胀土隧道的研究主要集中于开挖过程的支护结构分析,针对隧道运营期间的隧道结构的研究十分有限。然而,隧道建成后,长期的降雨入渗和胀缩过程的不断循环将严重威胁到膨胀土隧道的安全性及使用寿命。对此,本文依托南京平山浅埋膨胀土隧道项目,对膨胀土隧道运营期间降雨作用下的隧道结构力学响应与安全性进行探究,主要研究工作包括:(1)系统论述了膨胀土力学特性,通过室内试验,测定了土体的自由膨胀率以及无荷载膨胀率,根据现有的膨胀等级判断准则,确定了平山隧道膨胀土体的胀缩级别,得出了不同含水率对应的土体强度。同时,根据试验数据,拟合出了黏聚力、摩擦角与土体含水率之间的关系式。(2)根据温度场与湿度场微分方程的相似性,运用有限差分软件FLAC3D模拟了浅埋隧道降雨入渗过程,首先研究了非膨胀土增湿软化效应对衬砌内力及拱顶附加沉降的影响。之后探究了浅埋膨胀土隧道增湿过程中不同膨胀率、围岩变形模量和埋深下衬砌内力分布与衬砌安全系数的变化规律。最后,分析了干湿循环作用对膨胀土围岩安全储备系数、衬砌内力分布、衬砌安全系数及拱顶附加沉降的影响。研究结果表明:增湿软化效应、土体膨胀率与干湿循环作用对膨胀土浅埋隧道的衬砌内力与拱顶附加沉降的影响十分显著,在最不利情况下,膨胀率增加使得衬砌安全系数减小了34.5%,故在膨胀土隧道支护设计应充分考虑这三种影响因素,选取更为保守的安全系数。
[Abstract]:Expansive soil has many special mechanical properties, such as dilatancy and shrinkage, fissures, overconsolidation and so on. It brings many problems to the project, whether in the tunnel construction or after the completion of the tunnel. At present, The research on expansive soil tunnel in our country is mainly focused on the analysis of supporting structure during excavation, but the research on tunnel structure during tunnel operation is very limited. However, after the tunnel is completed, The continuous circulation of long-term rainfall infiltration and dilatation will seriously threaten the safety and service life of expansive soil tunnel. For this reason, this paper relies on the project of shallow buried expansive soil tunnel in Pingshan, Nanjing. This paper probes into the mechanical response and safety of the tunnel structure under the action of rainfall during the operation of the expansive soil tunnel. The main research work includes: 1) the mechanical properties of the expansive soil are systematically discussed, and the mechanical properties of the expansive soil are discussed through laboratory tests. The free expansion rate and load free expansion rate of soil are measured. According to the existing criterion of expansion grade, the expansion and shrinkage level of expansive soil in Pingshan Tunnel is determined, and the soil strength corresponding to different moisture content is obtained. At the same time, according to the test data, The relationship between cohesion, friction angle and soil moisture content is fitted. According to the similarity of differential equation between temperature field and humidity field, the rainfall infiltration process of shallow tunnel is simulated by using finite difference software FLAC3D. The influence of humidification and softening effect of non-expansive soil on lining internal force and additional settlement of arch roof is studied firstly, and then the different expansion ratio of shallow expansive soil tunnel during humidification process is discussed. The variation law of deformation modulus of surrounding rock and internal force distribution of lining under buried depth and lining safety coefficient are analyzed. Finally, the effect of dry and wet circulation on the safety reserve coefficient and lining internal force distribution of expansive soil surrounding rock is analyzed. Effects of lining safety factor and additional settlement on arch roof. The results show that the effect of humidification softening, soil swelling ratio and dry and wet circulation on the lining internal force of shallow buried tunnel with expansive soil and the additional settlement of arch roof are very significant. In the most disadvantageous case, the expansion rate increases the lining safety factor to reduce 34.5. therefore, in the expansive soil tunnel support design, we should fully consider these three factors, and select a more conservative safety factor.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U451

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