摘要
沈阳地铁某车站采用STS(Steel Tube Slab)管幕结构结合洞桩法进行修建,它是国内首次用来修建超浅埋暗挖车站,国内研究较少,工程经验不足,给现场施工带来一系列技术难题。本文旨在获取指导现场施工的关键性参数,采用FLAC^(3D)建立三维有限差分模型,对STS管幕结构支护下的车站施工过程进行研究,分析导洞不同的开挖顺序、台阶长度、开挖步距等因素对地表沉降和开挖面稳定性的影响。研究表明:先开挖下导洞,相比于其他方案引起地表沉降和地层损失率均较小,分别为4.05mm和0.0179%,并满足现场施工条件;不同台阶长度对开挖面前方土体纵向位移影响不大,但采用台阶法可以有效地控制开挖面纵向位移;台阶开挖长度每增加D/3,开挖面纵向地表沉降增加0.4mm^0.5mm,距开挖面前方约1.5D洞径内为扰动较大区域;导洞开挖步距在1m^4m内每增加1m,对开挖面纵向位移影响甚微,但地表沉降约增加2.8%~6.07%。
A new type of Steel Tube Slab combined with PBA method is designed to construct the subway station in Shenyang, which is firstly used to construct the ultra-shallow subsurface subway station. Up to now, little research is performed in this field which may cause a series of technological difficulties in construction. The FLAC^(3D) software is used to study the process of construction under the supporting structure STS, effects of parameters such as different excavation sequence, step lengths and excavation step distances for ground settlement and stability of excavation face are operated and analyzed. Study shows that excavating the lower pilot tunnel firstly have smaller ground settlement and loss ratio compared with other plans, that is, 4.04 mm and 0.0179%, respectively, which can meet the site construction conditions. Different length of steps have less effect on the longitudinal displacement of the soil in front of the excavation face, while it can effectively control the longitudinal displacement of the excavation face. The ground settlement will increase by 0.4 mm to 0.5 mm for each D/3 increment of step length, and about 1.5 times of the diameter of the tunnel in the front of the excavation face is a large disturbance area. The excavation step increases every 1 m to 4 m per 1 m, which has less effect on the longitudinal displacement of the excavation face, while the ground settlement increases about 4% of the total settlement.
出处
《应用力学学报》
CSCD
北大核心
2017年第4期756-762,共7页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金项目(51578116)
关键词
管幕工法
洞桩法
地铁车站
地表沉降
稳定性
数值模拟
Steel Tube Slab
PBA
subway station
ground settlement
stability
numerical simulation
