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.