Retaining wall - design of reinforced concrete structure

RETAINING WALL IS A MAJOUR STRUCTURE USED ON RIVER SIDES. PLUS THERE ARE MANY TYPE OF WALLS AS DESCRIBED IN THE SLIDE.

1. RETAINING WALL DESIGN OF REINFORCED CONCRETE STRUCTURE

2. -: CREATED BY:- KAVIN RAVAL 141080106026 -: SUBMITED TO:- PROF. VIVEK LOLARIYA CIVIL DEPARTMENT ACET

3. CONTENT INTRODUCTION STABILITY CONDITIONS COMPONENTS OF WALL

4. INTRODUCTION CHAPTER - 1

5. RETAINING WALL Retaining wall is a structure to retain soil, rock or other materials in a vertical condition. Hence they provide a lateral support to vertical slopes of soil that would otherwise collapse into a more natural shape.

6. Types of retaining wall Gravity wall Made of plain concrete or brick masonry The stability of the wall is maintained by its own weight made up to a height of 3 m.

7. Types of retaining wall Cantilever Retaining wall It consists of a vertical wall called stem, heel slab and toe slab. All elements of behave like cantilever beam of slab. Hence it is called cantilever retaining wall. The stability is maintained by the weight of the retaining wall and the earth on the heel slab of the retaining wall. Suitable upto 6 m. It may be T-shaped or L-shaped

8. Types of retaining wall Cantilever Retaining wall

9. Types of retaining wall Counterfort retaining wall In this wall heel slab and stem are connected by counterfort. Because of provision of counterforts, the vertical stem and heel slab acts as a continuous slab. The counterfort acts as a tension member to support the stem and reduces bending moment. The stability is maintained by the self weight of wall and by the weight of earth on the base slab. Suitable and economical for height more than 6 to 8 m.

10. Types of retaining wall Counterfort retaining wall

11. Types of retaining wall Bridge abutment Similar as cantilever wall, but top of stem is braced by the deck slab of bridge. The stem can be design as fixed at base and simply supported. (Propped cantilever)

12. Types of retaining wall Box culvert It acts as closed rigid frame. It consist of either single or multiple cells. It resists lateral pressure of earth and vehicle load.

13. Types of retaining wall Sheet pile wall Used to build continuous walls for waterfront structures and for temporary construction wall heights > 6 m if used with anchors. Can be made of steel, plastics, wood, pre-cast concrete.

14. Types of retaining wall Gabbion wall Gabbions are multi-celled, welded wire or rectangular wire mesh boxes, which are then rockfilled .

15. STABILITY CONDITIONS CHAPTER - 2

16. Stability Requirement of retaining wall Stability against overturning ( Cl.20.1, P: 33 ) It means factor of safety against overturning should be more than or equal to 1.55

17. Stability Requirement of retaining wall 2. Stability against sliding (Cl.20.2, P: 33 ) It means factor of safety against sliding should be more than or equal to 1.55

18. Stability Requirement of retaining wall 3. Stability against maximum pressure at the base ( stability against settlement) If the maximum pressure at base less than safe bearing capacity of soil, the wall is stable against settlement . Max. Pressure SBC of soil

19. Stability Requirement of retaining wall 4. No tension at base If the minimum pressure at base is greater than or equal to zero than, the wall is not under tension. Min. Pressure,

20. COMPONENTS OF WALL CHAPTER - 3

21. COMPONENTS OF RETAINING WALL BACKFILL HEEL SHEAR KEY TOE STEM FRONT

22. STEM Vertical stem in cantilever retaining wall resists earth pressure from backfill side and bends like a cantilever. The thickness of cantilever slab is larger at the base of stem and it decreases gradually upwards due to reduction of soil pressure with decrease in depth.

23. BASE SLAB The base slab form the foundation of the retaining wall. It consists of a heel slab and the toe slab. The heel slab acts as a horizontal cantilever under the combined action of the weight of the retaining earth from the top and the soil pressure acting from the soffit. The toe slab also acts as a cantilever under the action of the soil pressure acting upward. The stability of the wall is maintained by the weight of the earth fill and on the heel slab together with the self-weight of the structural elements of the retaining wall. Cantilever type retaining walls are suitable upto 5m depth of backfill.

24. SHEAR KEY The main purpose of installation of shear keys is to increase the extra passive resistance developed by the height of shear keys . However, active pressure developed by shear keys also increases simultaneously. The success of shear keys lies in the fact that the increase of passive pressure exceeds the increase in active pressure, resulting in a net improvement of sliding resistance. On the other hand, friction between the wall base and the foundation soils is normally about a fraction of the angle of internal resistance (i.e. about 0.8p ) where p is the angle of internal friction of foundation soil . When a shear key is installed at the base of the retaining wall, the failure surface is changed from the wall base/soil horizontal plane to a plane within foundation soil . Therefore, the friction angle mobilized in this case is p instead of 0.8p in the previous case and the sliding resistance can be enhanced.

25. BACKFILL Second, a retaining wall must have properly compacted backfill. Backfill refers to the dirt behind the wall. In order to provide proper drainage, at least 12 inches of granular backfill (gravel or a similar aggregate) should be installed directly behind the wall. Compacted native soil can be used to backfill the rest of the space behind the wall. If you intend to do landscaping behind the wall, a 6+ inch layer of native soil should also be placed over the gravel fill.

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