【作者】 杨颋；

【导师】 程谦恭；

【作者基本信息】 西南交通大学 ， 地质工程， 2013， 硕士

【摘要】 目前国内高速铁路设计对于大型采空区都进行了绕避,针对无法绕避的小采空区和采空巷道都采取了相应的工程措施,高速铁路采空区桥基桩台基础的应用在国内研究的较少,本文基于合福铁路上饶官山底特大桥59号墩台(DK499+584.180)和62号墩台(DK499+682.28),通过有限差分软件FLAC3D进行数值建模,研究分析了两个墩台在上部荷载作用下的沉降变形规律,荷载传递规律等。主要研究内容和成果如下：(1)对采空区桥基变形、稳定性、治理技术以及数值模拟方法的国内外研究现状进行了比较详细的叙述。(2)对两个墩台进行数值模拟分析后表明,在穿过采空区的桥墩下方应用桩基础加固可以减小桩间土承担的荷载,并显著减小地层和基础的沉降量,同时对采空区的沉降起到了抑制作用,证明这样的处理方法对采空区桥基有很好的加固效果。(3)对两个墩台的沉降变形进行研究分析,沉降随着荷载的增大而增大,不同深度的地层中,越是浅层土,沉降量越大；桩间土和桩顶的沉降量有细微差别,但可以忽略不计,桩土相对位移随着荷载增大而增大,但趋势也渐渐平缓。(4)对两个墩台的荷载传递机理进行研究分析,随着上部荷载的不断增大,桩身轴力从桩顶到桩底呈减小趋势,桩顶轴力最大,它的变化趋势随荷载的增大而增大；穿过采空区的桩,在该段由于没有与地层接触,轴力保持不变；桩身侧摩阻力随上部荷载的增大,先增大,然后再减小,穿过采空区的桩,在该段数值为零；桩土应力比以及桩荷载分担比随荷载增大而增大,桩开始承担更多的荷载。更多还原

【Abstract】 Mineral resources are rich and are widely distributed in China. Because of the historical reasons, most of the gobs for mining are abandoned without effective governance. There is a large area of ground subsidence and fissures in the stage of development of the mined-out area, although some mined-out areas have not been clearly changed, they still have a serious threat to the construction and the people’s lives and property. And the mined-out area is one of the potential geological disasters by human activities.In this dissertation, based on the number59pier section of DK499+584.180and the number62pier section of DK499+682.28in GuanShanDi bridge of HeFu railway, the numerical modeling is built by finite difference software FLAC3D, this dissertation studies the regularity of the settlement deformation and the load transfer of the two piers under the influence of the upper load. The main contents and results are as follows:(1) The research status of the numerical simulation method at home and abroad about the deformation of the bridge foundation, the stability and the governance of technology of the goaf is summarized systematically.(2) Analyze the numerical simulation, which shows that the pile foundation under the pier which is through the mined-out area is reinforced to reduce the sharing load in the soil among piles and reduce dramatically the settlement between the stratum and the foundation. Meanwhile, it is inhibiting the settlement of the mined-out area. All above prove this handling method has good reinforcement effect on the bridge foundation in the mined-out area.(3) A numerical simulation has been conducted to study the law of settlement, and the results suggested that sedimentation increases as the load increases. The more shallow location, the greater amount of settlement for soil layers at different depth. There are some differences in the soil among piles and the top of the pile for the pile settlement however it is negligible. The relative displacement of the pile-soil increases as the load increases and the trend has gradually getting gentle.(4) Analyze the load transfer mechanism of two piers, which suggests that the pile axial force reduces from the top of the pile to the bottom of the pile as the load increases, the axial force which is at the top of the pile is maximum and increases with the increment of the load: The axial force remains unchangeable while the pile passes through the gob, because there is no contact with the formation in this section; The pile skin friction increases first and then reduces as the load increases, the figure is zero in this section while the pile passes through the gob. The increase of the pile-soil stress ratio and the pile load sharing ratio shows that the piles begin to take on more loads.更多还原