- Shoring is a temporary structure to support temporarily an unsafe structure.
- Shoring is provided to a structure under following circumstances.
- When a structure has become or is likely to become unsafe due to,
- Differential settlement
- Bad workmanship
- Negligence of maintenance
- When an adjacent structure is to be dismantled.
- More skill, care and factor of safety is required while providing shoring. Supports may be given externally or internally or both
Types of Shoring:
There are three types of shoring:
- Raking or inclined shoring
- Flying or horizontal shoring
- Dead or vertical shoring.
1.Raking shoring or inclined:
- A raking shore consists of the following components:
- Wall plate
- Cleats
- Rakers or inclined member
- Needles
- Sole plate.
- Bracing
- Raking shores consist of inclined timber member called as raker. One end of which rests against a defects wall through wall plate and other end rests against sole plate which is embedded in ground at an inclination, to distribute load uniformly.
- The wall plate, about 20 to 25 cm wide and 5 to 7.5 cm thick is placed vertically along the face of the wall and is secured by means of needles of 10 cm x 7.5 cm sections.
- These needles penetrate the wall by about 10 cm. Wall plate is provided to distribute the load. Rakers are inter connected by braces and are tied at bottom by hoop iron.
2.Flying Shores or horizontal shores:
- Horizontal shores called as flying shores are the ideal shores to resist horizontal component of destabilising force.
- Such shores are used to give horizontal support to two adjacent, parallel party walls which have become unsafe due to removal or collapse of the intermediate building.
- The following points should be kept in mind while erecting the horizontal shores:
- Firstly, Centre line of horizontal shore and centre line of wall should meet at floor level.
- Wedges are driven in between straining piece and strut.
- Angle of the inclination of the strut should be between 45° to 60°.
- Single shores should be used only up to 9 m distance between two walls.
- Lastly, Flying shores are inserted when the old building is being removed and should be kept in position till the new unit is constructed.
3.Vertical shores or dead shores:
- This type of shoring is provided when :
- It is required to strengthen or replace existing unsafe foundation.
- To rebuild the defective lower part of the wall.
- To make larger doors, windows or openings in the existing walls.
- Dead shores consists of vertical members known as dead shores supporting horizontal members known as needles.
- The following steps are taken while providing the shoring:
- Firstly, Doors, windows and other openings floors and other parts of structure, which likely to be effected by removal of defective wall or demolition of wall, are properly strutted or supported.
- Secondly, The section of needles and dead shores should be adequate to transfer the load, which can estimated with fair degree of accuracy.
- Thirdly, the needles should be suitably braced.
- Fourthly, the projected ends of beams are supported by heavy vertical strut called dead shore.
- Fifthly, Dead shores are supported on sole plates. Folding wedges should be inserted between the two.
- The floors should be suitably supported from inside.
- Once again, whether all struts provided in all openings are properly fixed or not is checked and then defective portion is gradually removed.
- Lastly, the sequence of removal should be:
- Needles are removed.
- Struts from opening.
- Floor strutting inside.
- Raking shores if any.
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