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多年以来,我国在黄土地层中修建的铁路隧道,在衬砌结构设计上,沿用松散体理论分析方法,将黄土按照松散介质进行计算,设计的衬砌偏厚,刚度较大。而对土体的形变压力,尤其是侧向压力估计不足,断面形式不能适应黄土地层的力学特性,致使一些隧道的混凝土村砌出现开裂等病害。在黄土隧道施工中,多采用一般土质隧道惯用的上下导坑,分部开挖,木排架支撑,现浇混凝土衬砌顶替,先拱后墙的施工方法,这要消耗大量的建筑材料(特别是木材)。由于对土体反复扰动,因而招致很大的松散压力。施工中的坍塌、片帮时有发生,并增加了衬砌的负荷。
For many years, the railway tunnel constructed in the loess stratum of our country has adopted the loose body theory analysis method to calculate the lining structure, and the loess is calculated according to the loose medium. The designed lining is thicker and thicker. However, the deformation pressure of the soil, especially the lateral pressure, is not enough, and the cross-sectional form can not meet the mechanical properties of the loess stratum. As a result, cracks and other diseases occur in the concrete of some tunnels. In the construction of loess tunnels, it usually adopts the usual upper and lower pilot tunnels of general soil tunnels, excavation of sections, support of wooden racks, replacement of cast-in-place concrete linings and construction of back-arch walls first, which consumes a large amount of building materials Is wood). Due to repeated disturbance to the soil, it incurred a lot of loose pressure. The collapse of the construction, the film to help occur from time to time, and increased lining load.