|
Abstract The tunnel working face easily collapses when tunneling is conducted in the composited sandy soil, thus it is important to maintain the proper support pressure for the working face stability. According to the frictional characteristics of sandy soil，the upper bound analysis is applied to analyze the working face stability by using the improved 3D kenimatically admissible mechanisms, and the formula of the minimum support pressure for the working face stability is obtained. As the crossed soil is defined，the influence of the tunnel diameter，the depth ratio，the ground surface surcharge，the cohesion and the friction angle of the cover layers and the relative thickness ratio of cover layers on the support pressure is studied. This study presents an accurate estimation of support pressure for the tunnel working face stability in the composited sandy soils as well as an important theoretical reference to the similar practice projects.
|
|
Received: 24 October 2012
|
|
|
|
2013, Vol. 32 
