基于单桩载荷试验的铁路路基桩筏基础沉降计算  

Settlement Calculation of Pile Raft Foundation of Railway Subgrade Based on Single Pile Load Test

作　　者：陈洪运 宋绪国 郭帅杰 Chen Hongyun;Song Xuguo;Guo Shuaijie(China Railway Design Corporation,Tianjin 300251,China;Engineering Laboratory of Rail Traffic Survey and Design,China Railway Design Corporation,Tianjin 300251,China)

机构地区：[1]中国铁路设计集团有限公司,天津300251 [2]中国铁路设计集团有限公司轨道交通勘察设计工程实验室,天津300251

出　　处：《铁道勘察》2019年第6期30-35,共6页Railway Investigation and Surveying

基　　金：中国铁路设计集团有限公司科技开发课题(721613)

摘　　要：为有效利用单桩载荷试验数据预测群桩沉降,构建了铁路路基桩筏基础沉降计算模型,将铁路路基桩筏基础简化为多跨连续简支弹性地基梁模型,求解桩土荷载分担。通过单桩载荷试验获得单桩刚度,通过载荷板试验获得土单元刚度,考虑桩、土相互作用的影响,基于Muki理论与弹性叠加原理,获得群桩中的桩、土刚度,并给出了铁路路基群桩叠加范围的确定方法,进而可求得路基断面不同位置处的桩顶位移。选取京津城际2处桩筏路基为工程实例,实例一中实测路基断面中间沉降比坡脚沉降大11 mm,计算结果与实测结果一致,计算的总沉降量比实测值大10%(6 mm);实例二中检算得到的路基平均沉降为4 mm,本方法的计算结果约为5 mm,并给出了各桩的差异沉降。通过对比发现,计算结果与实测值和检算值吻合较好(偏安全),验证了研究成果的适用性。可在不增加工程量的情况下,充分利用单桩载荷试验数据,对铁路路基的沉降预估作补充分析,提高路基工程沉降变形的可控性与安全性。In order to effectively use the single pile load test data to predict group pile settlement,a settlement calculation model for pile raft foundation of railway subgrade is constructed.The pile raft foundation of the railway subgrade is simplified into a multi-span continuous simply supported elastic foundation beam model to solve the pile-soil load sharing ratio.The stiffness of single pile is obtained by single pile load test,and the stiffness of soil is obtained by loading plate test.Considering the influence of pile-soil interaction,based on Muki theory and elastic superposition principle,the stiffness of pile and soil in group pile is obtained.The method for determining the stacking range of group piles of the railway subgrade is given.Finally,the displacement of the top of the pile at different positions of the subgrade section is obtained.The two pile raft foundations of railway subgrade of the Beijing-Tianjin intercity are selected as engineering examples.Example 1:The center settlement is 11 mm larger than the slope foot settlement by measurement,in accordance with calculated results.The calculated settlement is 10%(6 mm)larger than the measured settlement.Example 2:the average settlement obtained by Borg Company is 4mm,the calculation result is about 5 mm,and the calculation result gives the differential settlement of each pile.The comparison shows,the calculation results are in good agreement with the measured values and the calculated values are safer.The applicability of the research results is verified.The research results can make full use of the single pile load test data without additional engineering quantity,make additional analysis of the settlement prediction of the railway subgrade,and improve the controllability and safety of the settlement deformation of the railway subgrade.

关 键 词：铁路路基 沉降 Muki理论 桩筏基础 单桩载荷试验 相互作用系数 

分 类 号：TU973.2[建筑科学—结构工程]