柴汶河大桥下伏采空区桥梁地基沉降变形规律研究及稳定性评价

发布时间：2018-01-12 16:41

本文关键词：柴汶河大桥下伏采空区桥梁地基沉降变形规律研究及稳定性评价　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：采空区在我国分部较广。随着社会现代化进程的加快,公路、铁路、桥梁、隧道等基础设施的建设日新月异,有的不得不在采空区上进行。新泰市向阳路柴汶河大桥为6-20m钢筋混凝土简支梁,位于新泰市东都镇东临。桥址区主要位于华源煤矿(原张庄煤矿)开采范围内。该处采空区开采年代久远,在开采过程中多次重复采动、多层开采,并且受汶南F1断层影响,使得采空区分布规律及特点更加复杂,严重影响桥梁安全。论文针对采空区桥梁地基进行研究,进行了如下研究工作。(1)对影响桥梁地基沉降的因素进行研究,并找出主要因素。(2)研究采空区的分布规律,包括空间分布形态、顶板管理方式、围岩结构类型及其物理力学性质等特征。(3)确定进行桥梁地基沉降分析的工况条件。利用UDEC离散元程序,分析研究在4种不同工况条件下桥梁地基的沉降变形规律。(4)研究在不同工况条件下桥基的稳定性,并对注浆治理效果进行模拟研究。通过开采条件判别法和概率积分法分别对研究区域作定性、定量评价,研究区域作为建筑场地属于不稳定场地,作为桥梁地基属于不稳定地基,两种评价方法结果一致。根据UDEC模拟计算结果,在采空区及岩溶未注浆工况下,建筑场地存在较大的剩余下沉量、剩余倾斜值和剩余水平变形值,为不稳定场地(地基)。在采空区及岩溶顶板处存在较为明显的边界滑动和屈服现象,有较大的剪切位移,应力场在采空区及岩溶顶板产生应力集中,顶板两端的最小主应力为拉应力,在采空区及岩溶附近区域沉降突然增大,使得沉降变形在垂向上不连续。在采空区及岩溶均注浆工况下,建筑场地剩余下沉量、剩余倾斜值和剩余水平变形值明显减小,为稳定场地(地基)。岩体中不存在较为明显的边界滑动和屈服现象,剪切位移几乎为零,应力集中现象消失,无拉应力出现。该类工况下岩体沉降变形过程实际为固结压密过程,变形曲线符合固结压密特征。通过对比分析注浆前和注浆后不同工况下的模拟计算结果,表明采用注浆方法能大幅度降低桥基的沉降变形,使得原本不稳定的桥基变为稳定,且工程效果比较理想。通过研究可以看出,影响桥梁地基稳定性的主要因素为采空区及岩溶的存在以及施加的桥梁荷载,而注浆方法对于控制桥梁基础的沉降变形效果明显,使桥基沉降变形在容许范围之内。
[Abstract]:With the rapid development of social modernization, the construction of highway, railway, bridge, tunnel and other infrastructure is changing with each passing day. Some have to be carried out in the goaf. The Chai Wenhe Bridge in Xiangyang Road Xintai City is a 6-20m reinforced concrete simply supported beam. Located in the east of Dongdu Town, Xintai City. The bridge site area is mainly located in the mining area of Huayuan Coal Mine (former Zhangzhuang Coal Mine). Under the influence of F1 fault of Wennan, the distribution law and characteristics of goaf are more complex, which seriously affect the safety of bridge. This paper studies the foundation of bridge in goaf. The research work is as follows: 1) study the factors that affect the settlement of bridge foundation, and find out the main factors. 2) study the distribution law of goaf, including spatial distribution form, roof management mode. The structural type of surrounding rock and its physical and mechanical properties are used to determine the working conditions of bridge foundation settlement analysis. UDEC discrete element program is used. The stability of bridge foundation under different working conditions is studied by analyzing and studying the settlement and deformation law of bridge foundation under four different working conditions. Through mining condition discrimination method and probability integration method, the study area is evaluated qualitatively and quantitatively, and the research area as a construction site belongs to unstable site. As the bridge foundation belongs to unstable foundation, the results of the two evaluation methods are consistent. According to the results of UDEC simulation, under the conditions of goaf and karst ungrouting, there is a large residual subsidence in the construction site. The residual tilting value and the residual horizontal deformation value are unstable sites (ground). There are obvious boundary sliding and yielding phenomena in goaf and karst roof, and large shear displacement. The stress field produces stress concentration in goaf and karst roof, the minimum principal stress at both ends of roof is tensile stress, and the settlement increases suddenly in goaf and near karst area. The settlement deformation is discontinuous in vertical direction. Under the conditions of goaf and karst grouting, the residual subsidence, residual tilt value and residual horizontal deformation value of the construction site are obviously reduced. In order to stabilize the site, there is no obvious boundary slip and yield phenomenon in the rock mass, the shear displacement is almost zero, and the stress concentration disappears. The deformation curve accords with the characteristics of consolidation and compaction. The simulation results before and after grouting are compared and analyzed. The results show that the grouting method can greatly reduce the settlement deformation of the bridge foundation, make the original unstable bridge foundation become stable, and the engineering effect is satisfactory. The main factors affecting the stability of bridge foundation are the existence of goaf and karst and the applied bridge load, while the grouting method has obvious effect on controlling the settlement and deformation of bridge foundation. The settlement deformation of the bridge foundation is within the allowable range.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U443.1

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