ELASTIC SUBGRADE MODE OF DEEP EXCAVATION IN GRAVEL AREA BASED ON CENTRIFUGE TESTING AND NUMERICAL SIMULATION

The engineering characteristic of round gravel soil is very special. We usually use elastic subgrade reaction method to design excavation engineering. However, the elastic subgrade calculation mode of excavation engineering in round gravel soil is not clear. This paper uses the setting in Guangxi University Station deep excavation of Nanning rail transit line 1. It carries out a centrifuge test to simulate the deep excavation engineering in gravel area, and also makes a Plaxis numerical simulating for comparation. We obtain the deformation of retaining wall and distribution of lateral earth pressure separately. Based on the data, also according to the principle of elastic subgrade reaction method, we futher analyze and examine the elastic subgrade calculation mode in active and passive areas of the deep excavation retaining wall. The results show that the magnitude of soil pressure in active area is related to the wall deformation. The necessary wall deformation value S/h to reach active soil pressure is about 0.1%. And the soil pressure distribution shape in active area is triangle on the top and rectangle on the bottom, which coincide the mode in elastic subgrade reaction method. And the subgrade horizontal coefficient 'K' in passive area increases approximately linearly with the depth. The elastic subgrade mode in passive area is similar to the 'm' method.