Spatial-Temporal Feature of Stress Field Evolution for Hard and Brittle Rock Excavation under High Stress Zone
The assistant tunnel of Jinping Second Stage Hydropower Station, which is covered by over 2 000 m-thick rock mass and has maximum principle stress over 60MPa, is used as an example to investigate laws, characteristic, ranges and velocity of stress redistribution with time along direction of parallel and perpendicular tunnel axes and balance time of stress field using numerical analysis method, based on Kelvin-Voigt-CWFS model which is a viscoelastoplastic combination model and is adaptable for describing time-dependant characteristics of hard and brittle rock mass. The result shows that the stress is firstly up and then down gradually at the two side walls and decreases quickly at vault, their principal vectors rotate gradually during the stress redistribution and 90％ adjustment of stress is finished at early several days after excavation. At equilibrium state, the stress is firstly up and then down to stability at the two side walls and up gradually to original stress state at vault with increase of distance from free face at the direction of perpendicular tunnel axes; the stress is firstly assembled, then falls down suddenly close to zero and finally increases to some value as observed profile is firstly close to and then far away from the tunnel face. The laws above mentioned are different from the laws obtained from middle and low stress environment. Knowing these laws, characteristic and mechanism of stress retribution is benefit for design, construction and supporting of tunnel and prevention and cure of disaster.
B.R.Chen X.T.Feng S.L.Huang
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and SoilMechani State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechan
国际会议
香港
英文
1-6
2009-05-19（万方平台首次上网日期，不代表论文的发表时间）