摘要
研究目的:受埋深、基础相邻作用的影响,洞桩法车站条形基础区别于一般地表浅埋基础,承载特性有所差异,中条基承载力相对薄弱但相较边条基承受更大荷载,成为条形基础形式应用的限制因素。本文汇总既有洞桩法车站资料,确定条形基础最不利承载状态,采用数值模拟的方式,探究洞桩法条形基础承载特性并制定合理地基处理方式。研究结论:(1)主体开挖完毕、底板尚未封闭时是洞桩法条形基础的最不利承载状态;(2)考虑基础相邻作用时荷载沉降曲线同原曲线出现“交错”现象,表现为低荷载阶段较原曲线沉降增大,而在高荷载阶段较原曲线沉降减小,整体使得p-s曲线前半段更平稳,延后了临塑、临界荷载点;(3)考虑埋深时,洞桩法中条基较地表条基承载力提升约30%,由于既有车站高度及中条基位置影响,基础埋深继续增大对地基承载力提升较小;(4)微型钢管桩注浆加固处理效果远优于同工况下仅采用微型钢管桩或仅注浆加固处理,且桩长不应小于2m,加固角度不应大于45°,在低荷载阶段,微型钢管桩发挥更好的加固效果,而在高荷载阶段,注浆发挥更好的加固效果;(5)本研究成果可为黄土地区暗挖工法地下工程设计与施工提供参考和借鉴。
Research purposes:The bearing characteristics of strip foundations in pile-beam-arch(PBA)method stations differ from conventional shallow surface foundations due to the influence of burial depth and adjacent foundation interactions.The central strip foundation exhibits relatively weaker bearing capacity yet bears greater loads compared to side strip foundations,becoming a limiting factor in the application of strip foundation types.This paper compiles existing data on PBA method stations to identify the most critical bearing state of strip foundations and employs numerical simulation to investigate their bearing behavior,subsequently proposing optimal ground improvement methods.Research conclusions:(1)The most unfavorable bearing state occurs after main structure excavation but before base slab closure.(2)Considering adjacent foundation effects,the load-settlement curve exhibits a"crossover"phenomenon—increased settlement at low loads but reduced settlement at high loads compared to isolated foundations,resulting in a flatter initial curve segment and delayed proportional/ultimate limit states.(3)At increased burial depths,PBA central strip foundations show approximately 30% higher bearing capacity than surface foundations,though further depth increases yield diminishing returns due to existing station height and central foundation positioning.(4)Grouted micro steel pipe piles achieve significantly better reinforcement than either pure micropiles or grouting alone,with optimal performance when pile length exceeds 2 m and installation angles are≤45°.Micropiles dominate reinforcement at low loads while grouting effects prevail at high loads.(5)The research findings can provide references for the design and construction of underground projects with the mined method in loess areas.
作者
范新明
邵莹
FAN Xinming;SHAO Ying(Xi'an Rail Transit Group Co.Ltd,Xi’an,Shaanxi 710008,China;China Railway First Survey and Design Institute)
出处
《铁道工程学报》
北大核心
2025年第8期87-93,共7页
Journal of Railway Engineering Society
基金
西安市轨道交通集团有限公司科研项目(D8-YJ-082021027)。
关键词
地铁车站
洞桩法
条形基础
承载特性
地基处理
subway station
pile-beam-arch(PBA)method
strip foundation
bearing behavior
ground improvement
作者简介
范新明,1971年出生,男,高级工程师;通讯作者:邵莹,1982年出生,男,正高级工程师。
