桩网结构路基承载特性的现场试验研究  

Research on bearing behavior of pile-net structure subgrade based on field test

作　　者：张良[1] 罗强[1] 陈亚美[1] 裴富营[1] 

机构地区：[1]西南交通大学土木工程学院,成都610031

出　　处：《岩土力学》2010年第12期3793-3800,共8页Rock and Soil Mechanics

基　　金：西南交通大学青年教师科研起步项目资助(No.2009Q074)

摘　　要：为了考察路堤荷载作用下桩网结构路基桩土间的荷载分担与传递、垫层筋带拉力的组成与分布,选择某新建铁路桩网结构路基试验工点进行了现场试验,测试了地基变形、路堤基底压力、孔隙水压力、桩身轴力和格栅拉力等数据。测试数据表明:①地基沉降以压密下沉为主,路基结构稳定,软土较厚一侧地基变形较大;②当桩、土间沉降差与桩间净距的比值为5.93%时,土拱效应完全发挥,之后增加的路堤荷载完全由桩承担;③桩间土竖向附加应力在加固区内沿深度呈K型分布;④筋带拉力沿路基横向呈M型分布,软土较厚一侧拉力较大;⑤筋带拉力由路堤荷载作用下的桩间筋带张力与路堤横向滑移引起的筋带拉力两部分组成,设计筋带时二者均需考虑。Field tests were conducted at a pile-net structure subgrade working point of a certain new railway to investigate the load sharing and transfer between piles and soil in pile-net structure subgrade, also the composition and distribution of tensile force in cushion. In which the deformation of foundation, the pressure at the bottom of embankment, the pore water pressure, the axial force of pile shaft, and the tensile force in grid were tested. We can get the results as follows. Firstly, compaction subsiding is major component of foundation settlement, indicating the subgrade is stable. The thicker the soft soil, the larger the foundation deformation. Secondly, the soil arch exerts fully when the ratio of settlement difference between pile and pile-inter soil to piles net distance is 5.93%. The subgrade load raised later will undertaken by piles completely. Thirdly, the distribution of vertical additional stress along with the depth of reinforced area shapes like a ＂K＂. Fourthly the distribution of tensile force in bar strip shapes like a ＂M＂, and the thicker the soft soil ,the larger the tensile force. Fifthly, the tensile force consists of two parts,. One is caused by subgrade loads, and the other is embankment＇s lateral sliding. The two parts must be considered when designing the bar strip.

关 键 词：桩网结构路基 现场试验 荷载分担与传递 筋带拉力 土拱 

分 类 号：TU472[建筑科学—结构工程]