摘要
为研究复合地层隧道施工引起的地表变形运动,以北京市典型复合地层特征为基础开展三维模型试验研究。依据相似理论,设计相似比为1∶50的模型试验装置。采用重晶石、砂壤土、熟石灰等材料配制力学特性差异显著的相似土体,模拟复合地层分层结构。设计不同测点位置,考虑土体密实度的影响,对不同工况下开挖起始端(监测面1)与末尾端(监测面2)的地表测点数值进行分析。填筑材料时,以原始试验设定锤击数15为参考,通过控制锤击次数调控土体密实度,分析不同密实度下各测点的位移变化情况。试验表明:(1)密实地层条件下,因颗粒紧密排列,盾构外壳与周围土体的摩擦导致土体发生剪切膨胀,导致地表隆起,且密实度越大,隆起程度越高;(2)松散地层条件下,因颗粒间空隙较大,土体并未发生剪切膨胀,因此地表未出现隆起,只有沉降。研究结果可为隧道施工地表隆沉预测相关理论的完善提供一定理论借鉴和实际参考。
The study investigates the ground movement caused by tunnel construction in composite strata.Based on the typical composite strata in Beijing,a three-dimensional model experiment was conducted.The experiment was designed according to the similarity theory,with a similarity ratio of 1∶50.Materials such as baryte,sandy loam,and quicklime were used to prepare similarity soils with significant differences in mechanics,simulating the stratified structure of composite strata.Different monitoring point locations were designed,and the soil compactness were considered.The monitoring points at the excavation start(monitoring surface 1)and end(monitoring surface 2)were analyzed under different working conditions.During the filling,the original test set the number of hammer strikes at 15 as a reference.By controlling the number of hammer strikes,the soil compactness was adjusted,and the displacement changes at various monitoring points under different compactness levels were analyzed.The experiment results showed that:(1)Under compacted conditions,due to the closely packed particles,friction between the shield casing and the surrounding soil caused shear dilation,leading to heave.The heave increased with higher soil compaction;(2)Under loose conditions,due to larger particle gaps,no shear dilation occurred,thus heave was not observed The above findings provided theoretical insights and practical reference value for the improvement of ground movement prediction in tunnel construction.
作者
廖鹏
黄琦
李国潜
郑佳哲
侯艳娟
LIAO Peng;HUANG Qi;LI Guoqian;ZHENG Jiazhe;HOU Yanjuan(Key Laboratory of Urban Underground Engineering,Beijing Jiaotong University,Beijing 100044,China;School of Mechanics and Civil Engineering,China University of Mining and Technology,Beijing 100083,China)
出处
《铁道勘察》
2025年第4期147-153,共7页
Railway Investigation and Surveying
基金
国家自然科学基金项目(52278387)。
关键词
地铁
隧道
剪切膨胀
模型试验
复合地层
地表隆沉
metro
tunnel
shear dilation
model test
composite stratum
ground heave and settlement
