双向增强复合地基桩土应力比计算方法研究

Study on Calculation Method of Pile-soil Stress Ratio of Bidirectional Reinforced Composite Foundation

研究目的:桩土应力比是反映双向增强复合地基工作特性的重要指标。由于路堤荷载下双向增强复合地基承载变形机理复杂,本文以双桩范围内的路堤与双向复合地基为研究对象,考虑路堤土拱效应、加筋层网兜效应、应力扩散效应等多重效应的共同作用,建立路堤-水平加筋垫层-竖向桩体-桩间土协调变形的二维理论分析模型,探究各影响因素对桩土应力比的影响规律。研究结论:(1)桩土应力比随填土重度、桩间距的增加而减小,随填料内摩擦角的增大呈先增加后减小趋势,随路堤填筑高度、格栅层数、填料黏聚力的增加而增大;(2)桩土应力比对各参数的敏感性由高到低排序为:桩间距、路堤填筑高度、路堤填土重度、路堤填料黏聚力、格栅层数及路堤填料内摩擦角;(3)本研究成果可为类似工程的桩土应力比计算提供理论依据及工程借鉴。

Research purposes:Pile-soil stress ratio is an important index to reflect the working characteristics of bidirectional reinforced composite foundation.Due to the complexity of the bearing deformation mechanism of bidirectional reinforced composite foundation under embankment load,this paper takes the embankment and bidirectional composite foundation in the range of double piles as the research object.Considering the combined effects of multiple effects such as embankment soil arching effect,reinforced layer mesh effect and stress diffusion effect,a two-dimensional theoretical analysis model of embankment-horizontal reinforced cushion-vertical pile-soil coordinated deformation is established to explore the influence of various influencing factors on pile-soil stress ratio.Research conclusions:(1)The pile-soil stress ratio decreases with the increase of filling weight and pile spacing.With the increase of the internal friction angle of the filler,it increases first and then decreases.It increases with the increase of embankment filling height,the number of grid layers and the cohesion of filler.(2)The sensitivity of pile-soil stress ratio to each parameter from high to low is:pile spacing,embankment filling height,embankment filling weight,embankment filling cohesion,grid layer number and embankment filling internal friction angle.(3)The research results can provide theoretical basis and engineering reference for the calculation of pile-soil stress ratio of similar projects.