水塘地区高速铁路浸水路基结构优化设计研究

Optimization Design of Soaking Subgrade of High-speed Railway in Pond Area

研究目的:高速铁路路基在水塘等长年浸水地段的长期稳定性受水流影响较为显著。目前关于浸水路基的研究主要集中于填料浸水后路基结构在各种工况下的稳定性分析,并未对既有高速铁路浸水路基的病害提出优化设计方法。通过对比线路标高和水塘设计水位的相对大小,将水塘地区路基划分为低水头和高水头两种工况,针对低水头浸水路基的常见边坡病害需对路基边坡防护进行设计优化,针对高水头水塘地区进行结构优化设计研究。研究结论:(1)边坡干砌片石下砂砾石反滤层和填料颗粒流失、坡脚溜坍是既有浸水路基的常见病害,采用砂砾石和无纺土工布包裹丝状渗排水网垫的双层反滤结构,坡脚设置防冲刷挡墙或浸水挡墙,能够提高渗流作用下路基边坡的长期稳定性;(2)鉴于传统浸水路基构造不适用于设计水位高于线路标高的现状,提出了由挡水坝、基床结构、基床以下路堤、防水层、封闭层等组成的"路堑式浸水路基"防渗抗浮设计方法;(3)在高速铁路水塘路基设计中应用"路堑式浸水路堤结构",相关结构抗渗技术以及边坡防护优化技术指导了水塘路基设计,具有一定的借鉴与指导作用。

Research purposes:The long-term stability of high-speed railway subgrade is significantly affected by water flow in long-term soaking section.At present,the research on soaking subgrade mainly focuses on the stability analysis of subgrade structure under various working conditions after the filling immersed in water,the optimal design method is not put forward.The subgrade in pond area is divided into two working conditions,high water head and low water head,by comparing the elevation of subgrade and design water level of the pond.It is necessary to optimize the design of subgrade slope protection in view of the common slope diseases of low water head soaking subgrade and study on structural optimization design for high water head soaking subgrade.Research conclusions:(1)Fine particle loss of sand gravel filter and subgrade filling under dry rubble revetment of slope and slope toe sliding both are the common disease of existing soaking subgrade.Applying the double-deck filter structure which is composed of sandy gravel and silk drainage network covered nonwoven Geotextile,or setting retaining wall on the toe of slope,the long-term stability of slope under seepage effect can be improved.(2)Since the traditional soaking subgrade structure cannot suit the situation that the design water level of the pond is higher than the elevation of subgrade,the anti-seepage and anti-floating design method of"cutting type soaking subgrade"is put forward,which is constituted by retaining dam,subgrade bed,earth structure,waterproof layer,sealing layer.(3)The application of"cutting type soaking subgrade",anti-seepage technology and slope protection optimization technology in design of high-speed railway reservoir subgrade has certain reference and guidance role.