英文翻译(原文)

GRA VITY RETAINING−WALL

1. INTRODUCTION

Retaining walls are structures used to provide stability for earth or other material where conditions disallow the mass to assume its natural slope, and are commonly used to hold back or support soilbanks,coal or ore piles, and water.

Retaining walls are classified, based on the method of achieving stability, into six principal types (Fig.1). The gravity-wall depends upon its weight, as the name implies, for stability. The cantilever wall is a reinforced-concrete wall that utilizes cantilever action to retain the mass behind the wall from assuming a natural slope. Stability of this wall is partially achieved from the weight of soil on the heel portion of the base slab. A counterfort retaining wall is similar to a cantilever retaining wall, except that it is used where the cantilever is long or for very high pressures behind wall and has counterforts, which tie the wall and base together, built at intervals along the wall to reduce the bending moments and sheers. As indicated in Fig.1c, the counterfort is behind the wall and subjected to tensile forces. A buttressed retaining wall is similar to a counterfort wall, except that the bracing is in front of the wall and is in compression instead of tension. Two other types of walls not considered further are crib walls, which are built-up members of pieces of precast concrete, metal, or timber and are supported by anchor pieces embedded in the soil for stability, and semigravity walls, which are walls intermediate between a true gravity and a cantilever wall.

(a)(b)(e)

(f)

Approah slab

Figure.1 Types of retaining walls: (a) Gravity walls of stone masonry, brick, or plain

concrete. Weight provides overturning and sliding stability; (b)

cantilever wall; (c) counterfort, or buttressed wall. If backfill covers counterforts, the wall is termed a counterfort; (d) crib wall; (e) semigravity wall (small amount of steel reinforcement is used); (f) bridge abutment.

Bridge abutments (Fig.1f) are often retaining walls with wing wall extensions to retain the approach fill and provide protection against erosion. They differ in two major respects from the usual retaining wall in:

1. They carry end reaction from the bridge span.

2. They are restrained at the top so that an active earth pressure is unlikely to develop. Foundation walls of buildings including residential construction are retaining walls whose function is to contain the earth out of basements.

Retaining walls must be of adequate proportions to resist overturning for (or excessive tilting) and sliding as well as being structurally adequate.

Terms used in retaining-wall design are shown in Fig.2. Note that the “toe ” is both the front base projection and the forward edge ; similarly for the “heel ”.

Figure.2 Principal terms used with retaining walls.