RESULTS OF ROCK STRESS MEASUREMENTS AND ENGINEERING APPLICATION OF A RAILWAY TUNNEL IN NORTHWESTERN YUNNAN

Rock stress state in situ is determined by the hydrofracturing method for rock stress measurement in a railway tunnel in northwestern Yunnan.According to the distribution features of the rock stress,combined with the mechanical parameters of the tunnel wall rocks,the stress filed in the tunnel area is simulated by using the three-dimensional finite elements.According to the in-situ stress measurements and three-dimensional finite element calculation,the basic features and distribution of the rock stress in engineering area are given,and the possibility of occurrence of geological hazards such as rock bursts during excavation of the tunnel is analyzed.Furthermore,the scientific basis for the lining design of the tunnel,choice of the tunnel's cross-section and determination of the axial direction of the tunnel is provided.