Deformation Prediction While Quickly Driving In Softrock Tunnel And Optimum Study Of Bracing Plan

Thesis is based on diaphragm gallery driving project of SICHUAN YELE hydroelectric station. It gives clear definition and classification of soft rock, and a comprehensive study has been made on the mechanism of soft rock failure. It makes decision on stability state of countryrock according to in-situ surveying datum, and grey prediction model is formed using the deformation curve of country rock.This model can predict latter displacement of country rock.Deeper analysis is also been counducted on countermeasure and mechanism of softrock tunnel,and gradation analysis method is applied to select the optimum bracing plan. Main contents and characters of the paper are as follows:(1) It systemly explains definition and classification of soft rock.lt gives analysis on geologic and engineering characters of soft rock,and deeper disscussion on failure causes of soft rock tunnel.It also shows the mechanism of deformation and failure.(2) It applies in-situ monitoring technique to access deformation of braced country rock and evaluation of its stability.Mathematical statistics and grey prediction model are applied to the latter deformation prediction.(3) It studies the bracing method and its mechanism of present soft rock tunnel project.The bracing plan and countermeasure are derived from deformation mechenism and engineering practice.Gradation analysis method is used to decide the optimum bracing plan.This paper is based on practical project and its achievement has been applied to engineering practice,resulting remarkable ecnomic and social effects.It also provides similar projects with valuable experience about bracing plan and research method of safe bracing.