Abstract
The paper discusses the strong asymmetric deformation and failure of the rock surfaces which have taken place in the 40–75 MPa marble during the excavation for the underground powerhouse and transformer chamber of the **** I Hydropower Station, southwest China. The deformation and damage of the rock mass closely relate to the magnitude of the geo-stresses, boundary conditions of the underground caverns, rock properties and the method and sequence of excavation. Ground stress test results show that the maximum principal stress reaches 35.7 MPa in the slope, and the average σ1 intersects with the axis of underground powerhouse at an angle of 28°. Strong displacements had taken place at the sidewalls of the caverns and significant instantaneous uplift deformation of the floor occurred, particularly when the first layer was excavated.
Résumé
L’article discute de la forte dissymétrie de déformation et de rupture des surfaces rocheuses qui ont eu lieu dans le massif de marbre, présentant une résistance de 40 à 75 MPa, pendant l’excavation réalisée pour l’usine souterraine et la salle des transformateurs de la station hydroélectrique de **** I, dans le sud-ouest de la Chine. Les déformations et dommages qui ont affecté la masse rocheuse sont étroitement en rapport avec l’intensité des contraintes in situ, les conditions aux limites relatives aux excavations souterraines, les propriétés des roches, la méthode et la séquence d’excavation. Des mesures de contraintes in situ montrent que la contrainte principale maximale atteint 35,7 MPa dans la pente, sa direction recoupant l’axe de l’usine souterraine suivant un angle de 28°. Des déplacements importants des parements de l’excavation souterraine ont eu lieu ainsi que des déformations instantanées de soulèvement du radier, particulièrement lorsque le premier niveau a été excavé.
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The authors are grateful for the financial support from Chinese Academy of Sciences under grant of KZCX2-YW-109-2.
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Wu, F., Hu, X., Gong, M. et al. Unloading deformation during layered excavation for the underground powerhouse of **** I Hydropower Station, southwest China. Bull Eng Geol Environ 69, 343–351 (2010). https://doi.org/10.1007/s10064-010-0308-9
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DOI: https://doi.org/10.1007/s10064-010-0308-9