摘要
新建隧道近距离穿越既有地铁隧道时,不但会诱发地表沉降,并且对既有地铁隧道也将产生不利影响。针对盾构近距离下穿既有隧道施工,构建二维颗粒流数值模型,研究新建盾构隧道近距离下穿既有隧道开挖面破坏形态、支护力与开挖位移关系、纵向地表变形及既有隧道周围土压力分布模式。研究表明:盾构开挖面支护压力随着开挖面位移的增加呈现先增加后减小的趋势,由于既有隧道的存在,开挖面逐渐远离既有隧道时,盾构开挖面支护压力较开挖面逐渐接近既有隧道时大。最大地表纵向沉降值出现在距离既有隧道中心2D范围内,随着盾构推进,新建隧道管片上方土压力表现为平缓增加的趋势,当远离既有隧道时,隧道上方水平土压力整体逐渐增加,盾构开挖面前方区域沿深度方向的土压力呈显著的非线性分布。研究成果可为今后此类施工提供理论依据和指导。
When several subway lines intersect,the excavation disturbance of the new shielded excavated tunnel in the crossing section is very complicated.When the existing tunnels are close to the new tunnel excavation,not only will the ground settlement be induced,but also will an adverse effect be made on the existing tunnels.For the construction form of the new shielded tunnel excavation under crossing the existing tunnel in active service,a 2 Ddiscrete element numerical model was established to study the failure surface of the shielded tunnel excavation passing through the existing tunnel nearby.In addition,the longitudinal ground deformation caused by the excavation and the distribution pattern of the soil pressure around the tunnel has also been analyzed.The results show that with the increase of the displacement of the excavation face,the support pressure of the shielded excavation increases first and then decreases.Due to the presence of the existing tunnel,the excavation face is gradually away from the existing tunnel,the pressure of the shielded excavation face is larger than that of the excavation approaching the existing tunnel.Further,the maximum ground surface settlement value is in the range of 2D from the center of the existing tunnel.With the advance of the shielded excavation,the earth pressure on the segment of the new tunnel appears to be a trend of gradual increase.When the tunnel is away from the existing tunnel,the lateral earth pressure on the top of the tunnel increases gradually,and the earth pressure along the depth direction in the front of the shielded excavation surface is significantly nonlinear.
作者
龙飞
LONG Fei(China Railway Shanghai Design Institute Group Co.Ltd.,Shanghai 200070)
出处
《土工基础》
2020年第5期587-592,共6页
Soil Engineering and Foundation
关键词
盾构隧道
近距离施工
开挖面稳定
颗粒流模拟
土压力分布模式
Shielded Tunnel Excavation
Adjacent Construction
Excavation Face Stability
Particle Flow Code Simulation
Earth Pressure Distribution Model
