北京黏性土地层大直径土压平衡盾构施工地层变形规律研究

Ground deformation characteristic due to large diameter slurry shield construction in clay in Beijing

以北京地铁14号线单洞大直径和双洞小直径土压平衡盾构工程为背景,结合现场监测数据,针对黏性土地层中盾构施工引起的地表变形过程和分布规律进行分析,得到以下规律:盾构隧道施工地表纵向变形呈现隆起、快速沉降、缓慢沉降和稳定四个阶段;单线大盾构隧道施工地表变形呈单峰状,可采用Peck公式进行描述,拟合得到K值平均为0.193,Vl值平均为0.114%;双洞小直径盾构隧道施工,地表变形呈单峰状或双峰状,最大沉降均位于先开挖隧道正上方,其变形可用双Peck公式进行描述,拟合得到的K值平均为0.347,Vl值平均为1.022%。研究结果可为类似工程提供借鉴及参考。

On in-situ monitoring has been performed to analyze the ground deformation characteristics due to the construction of onetube large diameter and two-tube small diameter EPB shield in Beijing Subway Line 14 in the clay ground. The results can be described as follows:ground surface deformation of shield tunnel construction composed of four stages:uplift,rapid settlement,slow settlement and stabilization; surface deformation of one-Tube large diameter tunnel construction shows a single Peck curve shape with an average K value of 0.193,and the Vl values for an average of 0.114%; Surface deformation of two-tube small diameter tunnels construction shows as single Peck curve shape or bimodal asymmetric shape. The construction of the second tunnel has changed the shape of surface settlement. Surface deformation can be described by double Peck formula and the K value and the Vl value are fitted as 0.347 and 1.022% in average. The results can be provided as a reference for the similar projects.