STUDY ON THE FAILURE MECHANISM OF THE VERTICAL OR STEEP CUTTING FACE AND ON THE ECONOMICAL EARTH RETAINING METHOD

Abstract

The new vertical earth cutting method (the N-VEC method) has been studied on the basis of the conception that the perfect sustaining of the failure zone caused by the excavation assures the stability of the whole cutting surface. The main supporting member in the N-VEC method are shotcrete with welded steel mesh and rockbolts.Unlike the conventional design thought no sliding surface is postulated in the design of this new method and the stress condition in the ground obtained by the numerical calculation is mainly considered to evaluate the stability of the cutting ground.FEM analysis is the main way of design to estimate the ground stress condition and the Mohr-Coulomb's failure hypothesis is adopted as the failure criterion. The new construction method was practically applied to the vertical cutting work 18.4m in height in the district where the ground consisted of the Inagi sand stratum, very soft sand.This paper deals with the basic concept of this new method, the way of numerical computer analysis and the practical construction works.