地铁隧道爆破开挖引起地表位移沉降的数值模拟

Numerical simulation of ground subsidence due to tunnel blasting excavation

以珠江三角洲城际快速轨道交通广州至佛山段工程隧道为依托工程,针对地表受到隧道开挖及爆破的影响引起的沉降问题,运用有限差分软件FLAC3D建立隧道开挖的数值模型,模拟隧道在爆破荷载作用下引起的地表沉降并分析其沉降规律。研究结果表明:在隧道单线洞壁施加爆破荷载后,隧道掌子面和一定范围内的开挖区地表位移沉降对隧道爆破开挖的响应较大,其地表沉降最大值为21.48 mm;在单线隧道爆破开挖引起地表沉降稳定后,进行第2条线隧道爆破开挖时,随着隧道已开挖区至隧道掌子面的距离增大,隧道地表最大位移沉降位置由两线隧道中心向两线隧道地表转变,沉降幅度与到隧道掌子面的距离有关;距隧道开挖掌子面越近,沉降量越大,最大沉降为32.99 mm。

Based on the project of intercity rapid track section of Guangzhou to Foshan in Pearl river delta, the FLAC3 Dsoftware was used to build the model of tunnel excavation. Surface subsidence caused by tunnel blasting excavation was computed, and the regulation of the surface subsidence was analyzed. The results show that the tunnel blasting excavation has impact on the surface subsidence from a certain range of excavation area to excavated face after applying the blast load on the tunnel wall. When the second tunnel is excavated, the maximal displacement displacement position of tunnel surface moves from the center line of the two tunnels to the tunnel; after the surface subsidence of the first excavates tunnel reaches stable, the magnitude of displacement is related to the distance between the excavated zone and the excavated face. The shorter the distance, the larger the displacement of the surface.