암반 응력조건에 따른 원형수직구 굴착시의 응력경로 및 응력모드 분석

Abstract

In-situ stresses change continuously as the depth of the shaft increases. Various in-situ stress conditions are classified using In-situ principal stress mode defined by the ratio of horizontal to vertical stress and the ratio of horizontal stresses. And the characteristics of in-situ principal stress ratio relating to stress condition are analysed. Secondary principal stress mode is used to classify the principal stresses states acting on the shaft wall after excavation according to the magnitude and direction of the principal stresses. And stress-path and stress-mode analyses are performed by using analytic solution and 3-dimensional numerical method for a circular-shaped shaft excavation with various in-situ stress conditions. With analysis of stress-path, correlation between In-situ principal stress mode and Secondary principal stress mode is estimated. Also, the effects of rock mass condition and support state on the stress-path and stress-mode during the shaft excavation are analysed.