PBA法非对称不均匀变形引起地表沉降规律研究

Study on the Law of Surface Subsidence Caused by Asy mmetric and Uneven Deformation of PBA Method

通过北京地铁某地铁车站的工程实践,研究了洞桩法(8导洞)工程从群洞开挖到扣拱期间的施工步序、工序转换和空间变形发展规律,综合分析了几何轴对称的车站结构断面在施工时差条件下导致的空间不均匀变形发展规律,对比工程数值模拟、实测数据,研究了工法执行差异是引起“地层结构”一体结构的空间不均匀空间变形的主要原因。经过对变形曲线的综合分析得知,形成的洞桩法结构周边的地层空间不均匀变形与空间临空、时空延续效应的叠加效果相关。最后针对性地制订工程对策并在工程中得以验证。本文的经验可以为类似工程的设计和施工提供有益的参考。

In this paper,through the study of the process transformation and settlement law of PBA method(8 pilot tunnel engineering)during the excavation of group tunnels to the arch buckle,the study comprehensively analyzes the spatial non-uniform deformation development law of the geometric axisymmetric station structure under the condition of construction time difference,and compares with the engineering numerical simulation and measured data.It is pointed out that the difference of construction method execution is the main reason for the uneven spatial deformation of“PBA tunnel and stratum”integrated structure.Through the comprehensive analysis of the deformation curve,it is found that the spatial uneven deformation of the surrounding strata is related to the superposition effect of spatial free space and space-time continuation effect.Finally,the project countermeasures are formulated and verified in the project.The experience of this paper can provide a useful reference for the design and construction of similar projects.