砂土地区浅埋非对称近接平行隧道施工地层位移分析

Analysis of Ground Settlement of Parallel Shallow Buried Unsymmetrical Close-spaced Tunnels in Sand Layers

基于隧道开挖引起地表沉降经典Peck公式,考虑砂土地区浅埋非对称近接平行隧道不同开挖步序,研究隧道周围土体横向水平位移及工后地表沉降规律。根据沉降叠加原理,建立考虑隧道内径均匀收敛非对称近接平行隧道修正Peck公式,并进行影响因素讨论。结果表明:土体横向水平位移集中在横通道转正洞及大直径断面拱脚处;隧道施工后地表沉降主要发生在小断面区域;地表横向沉降模拟值与计算值二者吻合较好,随着隧道圆心距L的增大,土体横向沉降量逐渐减小并由正态分布转变为马鞍形;隧道埋深H越大,沉降越大;非对称隧道施工时先开挖小断面隧道优于先开挖大断面隧道。

Ground settlement and horizontal displacement were analyzed based on FEM software of different excavation sequences. The modified peck equation was established considering even shrinkage of inner diameter based on superposition principle and different factors. The results showed that displacement was mainly distributed in small cross-section of two tunnels,horizontal displacement was mainly at arch bottom between horizontal passage and main tunnel. The simulation results of ground settlement and calculation results fit well,the displacement became smaller and transformed from normal distribution to saddle-shape with the enlargement of L,the larger settlement,the deeper bury depth H. Tunnel with smaller cross-section should be constructed earlier than large cross-section tunnel.