Categories, Design And Modes Of Failure Of Retaining Walls

Retaining wall is described as a fairly hard wall. It is constructed to give support to the soil mass horizontally to hold the soil at various levels on the two sides.

The following topics are covered in this construction article :-

• Types

• Design

• Modes of Failure

Types of retaining wall:

Usually the retaining walls are categorized as follow :-

Gravity Retaining Wall: Here weight is the key factors for these walls to maintain durability. In general, the walls are developed with plain concrete or masonry. For the structures having long height, these walls may be quite expensive.

Semi-gravity Retaining Wall: The section size regarding a gravity retaining wall is decreased with the placement of the fewer amount of adjacent to the back face. Such walls can be termed as semi-gravity walls.

Cantilever Retaining Wall: The Cantilever retaining walls are mainly developed with reinforced cement concrete. The wall comprises of a lean stem together with a base slab cast monolithically. For the construction that contains a height of 6 to 8 m, this type of wall is cost-effective.

Counterfort Retaining Wall: In Counterfort Retaining walls, there are lean vertical slabs alias counterforts which are positioned over the vertical steam recurrently. The counterforts join the vertical stem by the base slab. Hence, the vertical stem and the base slab extend amid counterforts. Here the counterforts are used to reduce the shear force and bending moments in the vertical stem and the base slab. The structures which contain a height over 6 to 8 m, the counterfort retaining walls are economical.

Guidelines for designing retaining walls: Before developing the realistic design, the soil parameters which can impact the earth pressure and the bearing capacity of the soil, must be analyzed properly. The soil parameters contain the unit weight of the soil, the angle of shearing resistance, the cohesion intercept and the angle of wall friction. The soil parameters are liable for detecting the lateral earth pressures and the bearing capacity of the soil. As soon as the earth pressures are detected, the retaining walls should be verified completely to find out the strength toward sliding, overturning, bearing capacity failure & tension.

Other modes of failure of retaining walls

Besides, three types of failures like sliding, overturning and bearing failure, the following two modes are also liable for collapsing of a retaining wall in case the soil below is feeble.

Shallow Shear Failure: This type of failure takes place along a cylindrical passing with the heel of the retaining wall owing to the extreme shear stresses along the cylindrical surface inside the soil mass. Usually the cause for safety alongside horizontal sliding is reduced contrary to the shallow shear failure. Due to this, if the factor of safety alongside sliding exceeds by 1.5, shallow shear failure will not occur.

Deep shear failure: It happens along a cylindrical surface, if there exists a feeble layer of soil below the wall a depth regarding 1.5 times the height of the wall. The trial and error processes are applied to ascertain the critical failure surface.

Ref : www.civileblog.com

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Published By

Rajib Dey

www.constructioncost.co

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Soil Reinforcement And It’s Application

This construction article is based on a B.Tech thesis for Civil Engineers. The article focuses on Soil Reinforcement Method and its application mainly the study of the behavior of centrally loaded strip foundation on multi layered geo-grid reinforced sand bed.

Soil Reinforcement refers to a robust and reliable method for improving the quality and strength of soil.

The hardened soil or mechanically arranged earth is a solid soil fill, reinforced with the study of pliable components like geogrids, geotextiles, metal bars and strips. It is currently developed in big development industry for building the structures like holding dividers, banks over delicate soil, steep inclines and so on.

The reinforced soil belongs to the soil in which its engineering behavior is enhanced by delivering the metallic, synthetic or geogrids.

The provision of geogrid reinforcement renders anisotropic mechanical properties, improve stiffness, tensile strengths as well as bearing capacity to the foundation soil.

Read More.

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Published By

Rajib Dey

www.constructioncost.co

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How to create a prestressed concrete unit on a prestressing concrete plant

Go through the following construction video that shows how to develop a prestressed concrete unit (Double T) on a prestressing concrete plant.

Double T is a multipurpose prestressing unit usually applied in parking structures but also be utilized in various buildings together with office buildings, industrial buildings etc. The Double Ts contain the potentiality of supporting span extending to 60ft as well as upto 120ft.

Step 1:
The initial step is to set up the necessary forms (here double T) as soon as the cleaning is completed. Under this construction video, a bed is arranged for 5 double T units having length 60ft long. Self stressing form is ideal for prestressing which can deal with prestressing compression force as well as the eccentricity of the strands.

Step 2:
The crew members can arrange strands in the form and transit them through prestressing plate. Strands are placed constantly over 5 units and later on segregated with the space provided by the dividers.

Step 3:
Strands already set in 2nd step are then tensioned to about 2 to 5 kips on the basis of gauge pressure reading. Here a mark is given on strands once the preload is applied. The strands are then tensioned and noted through gauge pressure on hydraulic pump. Quality control Technician then verifies elongation of strands against theoretical elongation. It necessitates that force on gauge and elongation measured should be equal with 5% tolerance limit. If it fails then strand should have been detensioned and then tensioned again.

For more information visit this link.

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Published By

Rajib Dey

www.constructioncost.co

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Usefulness of Construction Geometry for Roof Framing

Michael Nauth presents an informative construction video on construction geometry with Pythagoras' Theorem and Similar Triangles and Trigonometry. The geometries can simplify the estimation of roof framing.

Construction Geometries are used to draw shapes, angles or lines precisely.

The construction phase will be completed successfully with proper knowledge of fundamental geometry. Points, lines, measurements and angles are frequently utilized to lay out the building by following the architect drawings.

These elementary geometry elements are utilized by the grading subcontractor to outline the land and assure accurate drainage from property.

The concert, framing and roofing subcontractor applies strings and plums to create the blueprint. The roofers apply pitch and angles to assure drainage of rainwater.

The structural engineers utilize geometry in their design with the intension of estimating the spacing of the columns and beams for detecting exact strength of the building.

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Published By

Rajib Dey

www.constructioncost.co

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How to compute the design moment strength of a singly reinforced concrete beam

This construction video is made on Reinforced Concrete Design and it narrates the method for creating the estimate of the design moment strength concerning a singly reinforced concrete beam following the ACI Code.

The video highlights the following :-

The video highlights the following :-

i) How to draw the strain and stress profile at ultimate

ii) Force equilibrium to estimate neutral axis depth

iii) Examine assumptions (i.e. verifying steel yield) and decide phi

iv) Compute nominal moment and design moment

Go through this supportive article to learn more

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Published By

Rajib Dey

www.constructioncost.co

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Precast Concrete Advantages

In Precast concrete, a concrete member is casted and cured in a recyclable mold or "form" under a controlled environment and transmitted to the construction jobsite and elevated into place. On the other hand, the standard concrete is poured into site-specific forms and cured on site.

Precast concrete provides the following benefits :-

1. The precast concrete is developed with advanced quality concrete with greater technical control on the production of concrete in factory.

2. The material of precast concrete contains essential properties of thermal inertia (facilitating a more persistent temperature both in cold and hot regions) and acoustic insulation

3. The thermal mass indigenous to precast concrete makes itself energy efficient and minimizes the heating and cooling peaks and loads

4. Pre-stressing can be done smoothly to diminish the size and number of the structural members.

5. It is not mandatory to have joints in the precast construction.

6. Precast concrete structures are totally reusable and reduce the whole life cycle impact on the environment

7. Precast Concrete is completely safe to withstand impacts, blasts and natural disasters like earthquakes, tornadoes and floods.

8. Precast Concrete is developed with natural raw materials likw stones, gravels, sand, cement and these materials are accessible to almost everywhere and in a bulk quantity

9. The moulds used for generating the precast units are made of steel containing perfect dimension in all directions. These moulds are long-lasting and can be utilized repeatedly.

10. If necessary, the precast structures can be easily separated and can be used aptly anywhere.

11. Get rid of carrying and accumulating different types of concrete components for cast in situ work while selecting precast members.

12. Various precast units can save huge time for completing a construction quickly.

13. While setting up precast structures, the amount of scaffolding and formwork is significantly minimized.

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Published By

Rajib Dey

www.constructioncost.co

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How To Design Column With Excel

This excellent construction video will be very useful for Civil Engineers to learn the step-by-step processes for designing various types of axially loaded RCC column. By applying this construction sheet the reinforced concrete designers can simplify the designing the reinforced concrete columns like (braced, unbraced, slender, short, pinned, fixed etc).

The designers can estimate the necessary column reinforcement. Verify column for compression, bending and bi-axial bending. The Spreadsheet can also examine column slenderness and applies supplementary moments. It contains column cross-section diagram for recognizing efficiently.

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Published By

Rajib Dey

www.constructioncost.co

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