隧道围岩变形影响因素分析

新七道梁隧道地质条件复杂,本文对复杂条件下长大隧道影响围岩变形的施工因素进行分析。采用有限元法模拟施工中围岩的力学特征,表明隧道施工对围岩变形影响显著。同时,在隧道内布设大量收敛值量测断面,并长期监测,对隧道围岩收敛测量数据进行曲线分析。结果显示隧道开挖后围岩的变形具有时间相关性和空间相关性。变形包括三个阶段,即急剧变形阶段、缓慢增长阶段、基本稳定阶段。同时分析开挖方法、支护结构、邻近施工、施工工序等施工因素对围岩变形的影响。结果认为施工中开挖初期对围岩变形影响最大,而设置仰拱可减小隧道围岩变形,因此应选择对围岩扰动小的开挖方法,并及时进行后序施工。将围岩变形施工因素分析动态反馈于施工中,取得满意结果。

Analysis on Construction Factors of Surrounding Rock Deformation in Tunneling Works

The Xinqidaoliang Tunnel is under complicated geological conditions.Construction factors on deformation of the surrounding rock of the a long and large tunnel under complex conditions are analyzed.Mechanical characteristics of the surrounding rock during construction are simulated by a mathematical model.Results show that the influence is obvious.At the same time,a large amount of convergence measurement cross-sections are distributed on the job site and long-term monitoring and measurement are executed.Convergence data of the surrounding rock are analyzed by curves.It is pointed out that deformation of the surrounding rock has the characters of time pertinence and space pertinence.Deformation of the surrounding rock develops by three stages,i.e.,the rapidly-deforming stage,slowly-deforming stage and fundamentally-stable stage. Effects of the tunneling methods,support structure,adjacent construction and construction sequence on deformation of the surrouding rock are also analyzed.It is pointed out that excavation and initial supports affect deformation most significantly,whereas inverts can reduce the deformation.So it is essential to choose the tunneling methods producing little disturbance to the surrounding rock and to implement post-construction procedures in time.The analysis of rock deformation factors should be fed back to construction operation dynamically,thus producing satisfactory results in practice.