Experimental Test of Support Effect of Different Tunnel Support Systems
(1 Sichuan Provincial Transport Department Highway Planning, Survey, Design And Research Institute, Chengdu 610041; 2 MOE Key Laboratory of Transportation Tunnel Engineering, Southwest Jiaotong University, Chengdu 610031)
Abstract：
In order to study the support effects of different tunnel support systems, a 1∶30 model test is conducted to study the bearing capacities of different support systems based on a two-lane highway tunnel in surrounding rock of grade Ⅳ by using an external load with crown displacement of 20 mm (equal to 60 cm for the real tunnel) for the ultimate bearing capacity of the surrounding rock-support system. Test results show that: 1) the ultimate bearing capacity is much higher than that of an unlined tunnel for the conditions of surrounding rock + system anchor bolt +shotcrete, surrounding rock + shotcrete, or surrounding rock + system bolt, and the percentages of the bearing capacity increases are 56.8%, 48.3% and 47.8%, respectively, regarding the above three support system; 2) the support effect of system bolts + shotcrete is the best, followed by shotcrete and system bolts, with little difference between the support effects of system bolts and shotcrete; and 3) the combined support of system bolts and shotcrete has not reached the effect of 1+1=2 or ＞2, and it can be optimized.
2018, Vol. 55 