Due to the existence of high geostress and high geotemperature

the rockburst disaster is highly possible during the excavation of the newly-built Sangzhuling tunnel in the lasa-Nyingchi project. According to the unloading-temperature drop coupling action

the numerical model was conducted to simulate the stress release process during the tunnel excavation at different temperatures. At the same time

the secondary stress field was measured on site. The influence of high geotemperature on the circumferential stress was comparatively analyzed. Finally

the effect of high geotemperature on rockburst occurrence was discussed by considering different criteria. The results show that the indices of stress release rate and large temperature drop are used to reflect the excavation unloading-temperature drop coupling function

which can reasonably describ

e stress characteristics and rockburst occurrence law under high-geostress and high geotemperature in the excavation process. When the temperature drop exceeds 55 ℃ and the stress release coefficient is greater than 40%

σ

θ

and σ

1

linearly increase with the increase of stress release coefficient. The σ

θ

and σ

1

achieve maximum values when the stress release rate reaches 100%. It is found that the stress at the arch foot increases fastest

following at the vault. With the increase of the stress release coefficient

the rockburst occurs earlier due to the high geotemperature

and the grade of rock burst also increases.