不同开挖工法对大断面下穿古长城隧道的影响

The Influence of Different Excavation Methods on the Large-Section Tunnel under the Ancient Great Wall

大断面隧道施工会对上部建筑所处地层的形态造成一定程度影响。为满足文物局要求,确保施工安全,要尽可能控制隧道开挖对古长城的沉降影响。本文以某公路隧道下穿古长城项目为背景,对软弱围岩地质条件下常用的3种隧道开挖工法:CD法、CRD法和三台阶法,用有限元软件FLAC3D进行数值模拟,通过对比3种开挖工法监测点的沉降值与应力值,分析不同开挖工法对上部古长城结构沉降的影响。经整理分析结果,在确保长城结构安全的基础上,提出以CRD法作为综合效益最高的施工方案。

The construction of large cross-section tunnel will affect the formation of the upper building to a certain extent.In order to meet the requirements of the Cultural Relics Bureau and ensure construction safety,it is necessary to control the impact of tunnel excavation on the settlement of the ancient Great Wall as much as possible.In this paper,based on the project of a highway tunnel passing through the ancient Great Wall as the background,the three commonly-used tunnel excavation methods under soft surrounding rock geological conditions,i.e.CD method,CRD method and three-step method are used for numerical simulation with finite element software FLAC3D.The settlement value and stress value of the three kinds of excavation methods are compared to analyze the influence of different excavation methods on the settlement of the upper ancient Great Wall structure.In the final analysis,on the basis of ensuring the structural safety of the Great Wall,the CRD method was proposed as the construction plan with the highest comprehensive benefit.