基于当层法的新建隧道下穿既有隧道引起的变形预测模型研究

Study of Equivalent Layered Method Based Prediction Model for Deformations Caused by Construction of New Tunnels Undercrossing Existing Tunnels

对于新建隧道下穿既有隧道引起地层和既有结构的变形,常规的预测方法往往忽略了既有隧道刚度的影响,导致计算结果与实测结果有较大误差。文章基于当层法将既有隧道近似等效为一种岩土地层,考虑既有隧道刚度的影响,结合Peck公式建立一种新的新建隧道下穿既有隧道变形预测理论模型,推导出考虑既有刚度影响下的Peck公式解,并通过工程实例分析,验证了此方法的有效性。

As for the deformations of the strata and the existing structures caused by construction of new metro tun⁃nels undercrossing existing tunnels,calculation results by conventional prediction methods often have large errors compared to measured data because the complex influences of the existing structures are always neglected.Accord⁃ing to the equivalent layered method,an existing tunnel can be considered as an equivalent rock stratum instead.Based on the Peck formula,a theoretical model considering the stiffness of existing tunnels is established to predict the deformations caused by construction of a new tunnel undercrossing an existing tunnel,and a Peck formula solu⁃tion considering existing stiffness is derived.The validity of the proposed prediction method is verified by analysis of application cases.