斜向水泥土桩加固路基设计计算方法探讨

Discussion on Design and Calculating Method for Reinforcing Subgrde with Oblique Cement Soil Pile

研究目的:斜向水泥土桩是运行条件下既有铁路路基加固非常有效的方法之一,但其设计计算方法却一直是个空白,工程技术人员多凭借经验对水泥土桩间距、桩长和桩体强度进行设计。本文从斜向水泥土桩加固机理出发,建立斜向水泥土桩法的设计计算模型,结合分层总和沉降计算方法,提出确定斜向水泥土桩纵向间距及竖向排距的计算方法。研究结论:(1)该方法把两根对称的斜向水泥土桩简化为等效薄板;(2)薄板上、下部力和弯矩由平衡关系计算得到;(3)桩间距由桩体抗拉强度确定;(4)排距由路基加固后沉降减小量与未加固时总沉降之比(即减沉差比)确定,并把某一排减沉差比不大于5%作为控制标准;(5)该方法概念明确、计算简单,易于工程技术人员掌握,在既有路基加固工程中具有广阔的应用前景。

Research purposes： The oblique cement soil pile is one of effective ways to reinforce the subgrade of the existing railway being open to service. However, there is no specification on its design and calculating methods, the pile spacing, pile length and pile strength are usually designed with experience. In this paper, starting from the reinforcement mechanism of the oblique cement soil pile, the design and calculating model is built for the oblique cement soil pile, and combined with the layerwise summation method, a new method for determining the vertical spacing and vertical row distance of the oblique cement soil pile is presented. Research conclusions ： （ 1 ） With this method, two symmetrical oblique cement soil piles are simplified as two equivalent sheets. （2） The top and bottom forces of the sheet and the bending moment are obtained by calculation of the balance relationship. （3） The pile spacing is determined by the tensile strength of pile body. （4） The Row spacing is determined by the ratio of settlement reduction after the subgrade reinforced to the total settlement without reinforcement （the ratio of reducing subsidence difference ） , and the reducing subsidence ratio of no bigger than 5% of a row is regarded as the control standard. （5） The method is clear in concept, simple in calculation and easy to be mastered by engineering and technical personnels and has a wide applicable prospect in reinforcing the subgrade.