Kunio Saitoh

A DESIGN METHOD FOR SLURRY TRENCH WALL STABILITY IN SANDY GROUND BASED ON THE ELASTO-PLASTIC FEM

Abstract Deep-trench excavation supported by slurry has become a widely used technique for the construction of diaphragm walls. It has been proved by numbers of field tests, scale model tests and numerical analyses that the supporting effect of the slurry in the trench will provide sufficient stability for the deep-trench excavations. However, there is still neither a generally accepted theory of the failure mechanisms of the slurry trench, nor a widely used design method. This paper gives suggestions for the practical design on the stability of the slurry trench based on the elasto-plastic finite-element method (FEM) analysis, which consists of two parts. The first part is concerned with the evaluation of slurry trench stability in terms of safety factor. The safety factor was calculated using the shear strength reduction technique in the FEM and verified by comparison with centrifuge tests. The second part suggests a method for choosing the preliminary slurry parameters, i.e. the height of slurry filling and slurry density, based on the active earth pressure FEM.

Computation of Ground Vibration Around Pier by Using Axisymmetric Finite Element Method

We conducted on a study on a method of calculating ground vibration around a girder-type viaduct. This work focuses on the motion of the pier caused by the passing trains. Vibration acceleration in the pier at time of train passage was measured. Measurements revealed that vibration consisted chiefly of vertical translational behavior and rotational behavior around the horizontal axis. Analysis of ground vibration by axisymmetric finite element method considering these motions as excitation force characteristics was carried out. It was confirmed that the calculation results reproduce the ground vibration in the frequency range below 40 Hz.