6          Reducing Lateral Pressure on Structures

6.1         Introduction

Lateral pressure on structures can appear in a number of ways such as lateral earth pressure from normal backfilling, pressure due to soil expansion, earthquake loading, rock falls impact loading, pressure due to explosions.

Expanded Polystyrene, EPS, geofoam has been used in reducing lateral earth pressure when it is utilized as backfill next to a retaining wall or a bridge abutment or girder. As was mentioned before in chapter two, field measurements show reduction in the lateral pressure in a number of applications. Different shapes of foam were used next to the retaining structures varying between thin strips up to blocks of foam. Previous research work differed about the reason of reducing the pressure. Opinions varied on the effect of the lightweight itself in reducing the vertical stresses hence reducing the horizontal stresses; and between mobilizing the active state of pressure by utilizing the stiffness of foam. The geofoam backfill shown in photos 6-1 and 6-2 is utilized to reduce settlement. It will be shown later in this chapter that lateral pressure will be reduced only to a limiting value in such cases. This chapter studies three ways to reduce stresses due to lateral pressure on structures. Both laboratory work and field records are shown. Numerical analysis was also used in this study.

Photo 6‑1 Reducing Settlement Utilizing Geofoam

Photo 6‑2 Geofoam Flushed to a Bridge Girder