Development of a new type of foam concrete and its application on stability analysis of large-span soft rock tunnel

WANG Hui(王辉), CHEN Wei-zhong(陈卫忠), TAN Xian-jun(谭贤君), TIAN Hong-ming(田洪铭), CAO Jun-jie(曹俊杰)

(State Key Laboratory of Geomechanics and Geotechnical Engineering (Institute of Rock and Soil Mechanics,
Chinese Academy of Sciences), Wuhan 430071, China)

Abstract:The long-term stability of large-span soft rock tunnel is influenced greatly by the creep effect of surrounding rock. The development of a new type of foam concrete which has the property of high compressibility and low ductility was introduced. And it was made as filling material of reserved deformation layer between the first lining and the second lining used in large-span soft rock tunnel. The effect of the new type of foam concrete was simulated as filling material of reserved deformation layer using numerical simulation. Through the comparison with the common large-span soft rock tunnel, the vault settlement and surrounding convergence are reduced by about 61% and 45%, respectively, after creep of 100 a. And in the second lining, the plastic zone reduces apparently and the maximum equivalent plastic strain decreases relatively. So, it can be found that the application of the new type of foam concrete as the filling material of reserved deformation layer can relieve the excessive force in second lining induced by rock creep, reduce its deformation and improve the stability of tunnel.

Key words:foam concrete; large-span soft rock tunnel; stability analysis; numerical simulation