人工冻土融沉对地层位移场影响的三维有限元分析

A numerical simulation study on ground displacement field of thaw-settlement in artificial freezing soil

为揭示人工冻土解冻对地层位移场影响的规律,以某地铁区间隧道盾构出洞水平冻结工程为例,对由人工冻土融沉引起的地层位移进行了三维有限元分析。计算结果表明:地表沉降可分为缓慢沉降、快速沉降、平稳沉降和固结沉降4个阶段;在隧道中轴线上方,随着与出洞口距离的增大,地表沉降先增大后减小;地面沉降在横断面上的分布呈近似正态分布曲线,随着与中轴线水平距离的增加,地表沉降逐渐减小,存在明显的曲线反弯点;地面水平位移随距隧道中轴线距离的增加,先增大后减小,最大水平位移对应于地面沉降分布曲线反弯点对应的位置;隧道上方由融沉引起的土体沉降随深度的增加而增加,距离冻结区域越远,土体沉降越小。

To reveal the ground settlement regularities of thawing of artificial freezing soil,based on a horizontal freezing engineering project of shield tunneling for construction of a subway,the ground displacement induced by thaw-settlement in artificial freezing soil was studied with 3D numerical simulation analysis.The results showed that settlement of ground surface can be divided into 4 stages： slow settlement,rapid subsidence,stationary settlement and consolidation settlement.Above the tunnel axis,with the increase of distance from the sealed door,ground surface settlement was increased first and then decreased.Land subsidence in the cross section was similar to normal distribution curve.With the increase of horizontal distance from the axis,land subsidence was decreased and there is an obvious inflection point of the curve.With the increase of distance from the tunnel axis,the hori-zontal distance of land increased first and then decreased.The maximum horizontal displacement corresponds to the position of inflection point.The ground settlement above the tunnel caused by the thaw-settlement increased with the increase of depth.The ground settlement was smaller when the distance was farther away from the freez-ing zone.