Abstract
The stress state and principal stress axis changes of the stress-field tensor are analyzed during the advancement of a tunnel face on the basis of a given case study of the Jinping II Hydropower Station in China. First, the prevailing pole diagram in geology is used to illustrate the rotation of the stress axes as the tunnel face advances. The results show that the orientation adjustments of principal stresses in different positions near the tunnel boundary share common characteristics. The major and minor principal stress axes ahead of the tunnel face will rotate to intersect with the excavation surface at an angle, with the intermediate principal stress axis being almost parallel to the excavation surface. Furthermore, the stress triaxiality that is commonly used to indicate the deformation and damage of metal materials is introduced to describe the stress state change of the excavation-induced stress. The stress triaxiality is found to represent the stress state change due to the variation in both the magnitude and orientation of the stress-field tensor. According to the physical meaning and the change law of the stress triaxiality, stress disturbance during tunnel excavation can be divided into four stages, and the stress disturbance zone is divided into a strong disturbance zone and a weak disturbance zone. The disturbance characteristics of different stages and the distribution patterns of various zones are analyzed, which may be useful for practical application in the design and construction of rock tunnels.
Highlights
Research ArticleNumerical Modeling of Stress Disturbance Characteristics during Tunnel Excavation
It is widely known that tunnel excavation can lead to stress changes and possible damage ahead of a tunnel face
Many researchers have carried out studies on stress disturbance during tunnel excavation by means of various methods such as theoretical analysis and field tests. e main representative studies are the Underground Research Laboratory (URL) of Atomic Energy of Canada Limited (AECL) (1989–1996), which carried out a large number of field tests and monitoring work for Lac du Bonnet granite [7, 8]; the Swedish Nuclear Fuel and Waste Management Company (SKB), which conducted a variety of tests and analysis work based on the Hard Rock Laboratory on the island Aspoof southeast Sweden [9]
Summary
Numerical Modeling of Stress Disturbance Characteristics during Tunnel Excavation. E stress state and principal stress axis changes of the stress-field tensor are analyzed during the advancement of a tunnel face on the basis of a given case study of the Jinping II Hydropower Station in China. The prevailing pole diagram in geology is used to illustrate the rotation of the stress axes as the tunnel face advances. E results show that the orientation adjustments of principal stresses in different positions near the tunnel boundary share common characteristics. According to the physical meaning and the change law of the stress triaxiality, stress disturbance during tunnel excavation can be divided into four stages, and the stress disturbance zone is divided into a strong disturbance zone and a weak disturbance zone. According to the physical meaning and the change law of the stress triaxiality, stress disturbance during tunnel excavation can be divided into four stages, and the stress disturbance zone is divided into a strong disturbance zone and a weak disturbance zone. e disturbance characteristics of different stages and the distribution patterns of various zones are analyzed, which may be useful for practical application in the design and construction of rock tunnels
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