含空洞砂卵石地层盾构隧道引起地面沉降研究

STUDY ON THE SURFACE SUBSIDENCE CAUSED BY SHIELD TUNNEL IN SAND PEBBLE STRATUM CONTAINING CAVITY

砂卵石地层普遍存在地下空洞,在该区域进行盾构隧道施工容易扰动砂卵石地层,若含有空洞则可能会引发空洞塌陷破坏,造成较大的地面沉降。基于离散元软件Yade,建立含空洞砂卵石地层单线盾构隧道施工模型,研究单空洞位置、单空洞直径、多空洞的组合形式对地面沉降的影响,得到空洞对盾构隧道施工引起的地面沉降的影响规律。研究结果表明,含空洞地层中,当空洞位于隧道正上方引起的地面沉降最大,而空洞位于隧道正侧方引起的地面沉降最小;无论空洞处于哪种位置,空洞直径越大,引起的地面沉降越大;空洞位于隧道正上方或者正侧方时,地面沉降值与空洞直径呈现近似二次函数关系,空洞在隧道斜上方时,在某些区间内地面沉降值与空洞直径呈现线性关系;空洞数量越多,引起的地面沉降越大。两空洞工况下,空洞分别位于隧道正上方与斜上方时引起的地面沉降最大。三空洞工况下,空洞分别位于正上方、正侧方、正侧方时引起的地面沉降最大。

Under sand pebble stratum,cavities are subjected to disturbance from construction of shield tunnels,resulting in large surface subsidence at this area.The model of the construction of a single line shield tunnel with cavities in sand pebble stratum is established through discrete element method by Yade software,in which the single cavity's location,diameter,and combination with other cavities on surface subsidence are investigated,and the rule of surface subsidence affected by cavities during shield tunnel construction is obtained.The results show that the surface subsidence caused by the hollow being directly above the tunnel is the largest,while the surface subsidence caused by the cavity being located directly on the side of the tunnel is the smallest.Regardless of the position of the cavity,the larger the diameter of the cavity,the greater the ground settlement causes,and the surface subsidence and cavity dimension have an almost quadratic connection when the cavity is located above and on the side of the tunnel.In some sections,the surface subsidence and cavity diameter have a linear relationship when the cavity is slanted above the tunnel.The amount of surface subsidence induced increases with the quantity of cavities.For the working condition with two cavities,the surface subsidence is greatest when one cavity is directly above the tunnel and the other is obliquely above the tunnel.The largest surface subsidence under the three-cavity condition occurs when the cavities are located directly above,on the right side,and on the right side.