冻土地区路桥过渡段不均匀沉降的产生机理及冻害防治技术研究

发布时间：2019-06-18 17:11

【摘要】：路桥过渡段的差异沉降是铁路、公路工程中普遍存在的问题,尤其是通车后在动力作用下的沉降表现更为明显。多年冻土地区路桥过渡段的问题,除了存在纵向差异沉降以外,还有与下伏冻土的力学性质有关的特有工程问题。由调查分析数据可知,青藏铁路路桥过渡段沉降病害非常普遍,且沉降差大;目前主要采用在桥台后的沉降差异空间中填埋道渣找平的方法。这种方法虽然短时间内有效,但未能从机理上控制路基的下沉,而且会产生新的病害。由于病害机理不同,融区的相应经验和技术也很难有效应用于冻土区,而目前对于冻土地区路桥过渡段的研究很少。基于此,本文以研究冻土地区路桥过渡段差异沉降的产生机理和治理措施为目的。在室内模型试验中,通过埋设热源的方法模拟地下水的影响;通过设置不同刚度的路桥间搭板、不同性质的路基填料观测其治理效果;同时利用ANSYS软件建立数值计算模型,分析热棒对差异沉降的治理效果。可得出以下结论:(1)全球气候变暖、地下暗河的动态变化会影响冻土的力学性质,不同路基的结构和材料可对辐射、对流、传导起到调控作用,三者均能影响到路桥过渡段的沉降趋势。(2)在室内模拟试验中,通过设置热源模拟地下水效应,可知,在地下水作用下,桥台和路基的沉降量都有明显的增大,并且桥台的沉降量比路基明显偏大,即钢管桩对地下水更为敏感。(3)室内模拟试验中,设置路桥间搭板之后,在一定程度上可减小差异沉降,并且随着路桥间搭板刚度的增大,差异沉降的减小量亦越大;但基底一旦发生沉陷,修补极为困难。采用不同性质的过渡段路基填料,其刚度越大,差异沉降越小,但填料的刚度并不是越大越好;而对于已投入运营的线路,可以通过注水泥浆的方法来改善路基填料性能。但是,以上两种方法对多年冻土的热工程病害没有明显的改善。(4)通过ANSYS软件,计算分析热棒对冻土区路桥过渡段差异沉降的治理效果,可知,在路基埋设热棒后,可以有效减小路基的沉降量。而热棒对冻土区路桥过渡段沉降差的治理效果很微弱。综合以上,要想从根本上治理差异沉降病害,须提出综合治理方案。
[Abstract]:The differential settlement of road and bridge transition section is a railway, which is a common problem in highway engineering, especially the settlement under dynamic action after opening to traffic. In addition to the longitudinal differential settlement, there are some special engineering problems related to the mechanical properties of underlying frozen soils in the transitional section of roads and bridges in permafrost areas. From the investigation and analysis data, it can be seen that the settlement disease of the transitional section of Qinghai-Tibet Railway is very common, and the settlement difference is large. At present, the method of leveling the landfill slag in the space of settlement difference behind the bridge platform is mainly adopted. Although this method is effective for a short time, it can not control the subsidence of subgrade from the mechanism, and will produce new diseases. Because of the different disease mechanism, the corresponding experience and technology of the melting area are difficult to be effectively applied to the frozen soil area, but there is little research on the road and bridge transition section in the frozen soil area at present. Based on this, the purpose of this paper is to study the mechanism and treatment measures of differential settlement in the transition section of roads and bridges in permafrost areas. In the laboratory model test, the influence of groundwater is simulated by embedding heat source; the treatment effect is observed by setting up different stiffness of road and bridge slabs and different properties of subgrade filling; at the same time, the numerical calculation model is established by using ANSYS software to analyze the treatment effect of heat bar on differential settlement. The following conclusions can be drawn: (1) the dynamic change of underground dark river will affect the mechanical properties of frozen soil, the structure and materials of different roadbed can regulate radiation, convective flow and conduction, and all of them can affect the settlement trend of road and bridge transition section. (2) in laboratory simulation test, by setting heat source to simulate groundwater effect, it can be seen that under the action of groundwater, The settlement of bridge platform and subgrade is obviously increased, and the settlement of bridge platform is obviously larger than that of subgrade, that is to say, steel pipe pile is more sensitive to groundwater. (3) in laboratory simulation test, the differential settlement can be reduced to a certain extent after setting up the slab between roads and bridges, and with the increase of stiffness between roads and bridges, the reduction of differential settlement is greater; However, once the basement has sunk, it is extremely difficult to repair it. When different properties of subgrade filling are used, the greater the stiffness of subgrade filling is, the smaller the differential settlement is, but the greater the stiffness of filling is, the better the stiffness is. For the lines that have been put into operation, the performance of subgrade filling can be improved by injecting water mud. However, the above two methods have no obvious improvement on the thermal engineering diseases of permafrost. (4) through ANSYS software, the treatment effect of hot rod on the differential settlement of road and bridge transition section in frozen soil area is calculated and analyzed, it can be seen that the settlement of subgrade can be effectively reduced after the hot rod is embedded in the subgrade. However, the effect of hot rod on settlement difference of road and bridge transition section in frozen soil area is very weak. In order to fundamentally control the differential settlement diseases, a comprehensive control scheme must be put forward.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.1

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