桩板结构在强发育岩溶无砟轨道中的应用研究

Application Study of the Structure of RC Pile-plank in Strong Development of Karst and Ballastless Track Railway

研究目的:强烈发育的岩溶地区修建无砟轨道时,有条件设桥地段多以桥梁通过,对没有改桥条件的车站咽喉区高填方路基的设计方案一直以来就是一道难题,因为路基填筑会增加岩溶顶板的附加荷载,进一步恶化岩溶稳定性,进而加速岩溶塌陷的发生。本文旨在研究一种既能控制路基填筑对岩溶的影响、减小岩溶塌陷对路基安全稳定的影响,又能控制岩溶覆盖土层的压缩沉降的设计方案。研究结论:(1)埋入式托梁桩板结构利用其承载板将上部荷载通过混凝土托梁传递到下部桩体,进而把荷载扩散到桩底下卧硬层或岩石层,既可解决岩溶地基处理问题,又可避免填土对岩溶顶板的附加荷载;(2)托梁式桩板结构具有良好的整体性和稳定性;(3)托梁式桩板结构的受力计算从多桩超静定结构转化为静定结构,可简化计算;(4)托梁式桩板结构可用于基底软硬不均差异沉降控制困难的路基设计,并具有较好的技术和经济优越性,可以在类似的山区铁路工程中推广应用。

Research purposes： When build ballastless track railway in the karst region with strong development, the district which is conditional to set bridge selects bridges, but for the station throat area without the condition of bridge, the high fill subgrade design is a difficult problem, because filling the embankment will increase the additional load of karst roof, accelerate the occurrence of karst collapse. How to take measures to control the influence of the subgrade filling on karst, reduce the impact of karst collapse on safety and stability of subgrade, and control the compression settlement of covered soil on karst is the key to solve the problem. Research conclusions： The embedded type RC pile - plank with joist is the use of the upper bearing plank, the load will transmit to the pile, the pile will transfer load to the stable bedrock, both can solve the problem of karst ground treatment, and avoid the additional load of the filling against karst roof. The type RC pile - plank with joist has good integrity and stability. Its stress calculation changes from multiple pile of statically indeterminate structure to statically determinate structure, simplifies the calculation. It can be used for basal uneven hardness and difficult control of differential settlement of subgrade design, and has a good technical and economic superiority, can be applied in similar mountain railway engineering.