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3 years ago CementConcrete
What is Shoring?
Shoring is lateral support for an unsafe structure that is constructed for temporary support. These support a wall laterally. Shoring are used under the following conditions:
- When a wall shows signs of bulging out due tobad workmanship.
- When we have to repair a crack on the wall dueto unequal settlement of foundation.
- When an adjacent structure is to be dismantled.
- When openings are to be made or enlarged in thewall.
Types of Shoring
Shores may be of the following types:
1. Raking Shores
In this method, inclined members, called rakers are used to give lateral support to the wall as shown in Fig.1.
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A raking shore consists of the following components:
- Rakers or inclined members,
- Wall plate,
- Bracing, and
- Sole plate.
The wall plate (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.
These needles (10 cm x 7.5 cm)penetrate the wall by about 10 to 15 cm. In order that the needles do not getsheared off due to the thrust of the raker, the needles are further strengthenedby means of cleats which are nailed directly to the wall plate.
Rakers about against the needles in such a way that the centerline of the raker and the wall meet at the floor level. Thus, there will be one raker corresponding to each floor. These rakers are inter-connected by struts, to prevent their buckling.
An inclined sole plate is embedded into theground on which the feet of rakers are connected. The feet of rakers arefurther stiffened near the sole plate by means of hoop iron. The wall platedistribute the pressure to the wall uniformly.
The following points are keep inmind when using Raking shores:
- Rakers should be inclined to the ground by 45° to 75°, but 45° is more effective. The Top of raker should not be inclined steeper than 75°.
- For tall buildings, the length of raker can be reduced by introducing rider raker.
- Rakers should be properly braced at intervals.
- The size of the rakers should be decided on the basis of anticipated thrust from the wall.
- The centre line of a raker and the wall are maintained at the same level of floor.
- If longer length of the wall needs support, shoring may be spaced at 3 to 4.5 m spacing, depending upon the requirements.
- The sole plate should be properly embedded into the ground, at an inclination and should be of proper sectiod. The sole plate should be sufficient widen so that it can easily support all the rakers, and a cleat provided along the outer edge.
- Wedges should not be used on sole plates since they are likely to give was under vibrations which are likely to occur.
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2.Flying or Horizontal Shores
Flying shores are a support system which provides horizontal support to two parallel party walls when removal or collapse of the intermediate building takes place.
All types of shoring system of supporting the unsafe structure in which the shores do not reach the ground are the flying shores. If the walls are quite near to each other (distance up to 9 m), single flying shore (Fig.2)
It consists of well plates, needles cleats, struts, horizontal shore straining pieces and folding wedges. When the distance between the walls is more, a compound or double flying shore (Fig.3) may be provided.
In this system operations of the building inthe ground are not obstructed.
The following points should be kept in mind while connecting the flying shores:
- The center lines of flying shore and struts and those of the walls should meet at floor levels of the two buildings. If the floor level are different, the horizontal shore should be placed either mid-way between the levels of the two floor of equal strength, or it should be placed at the level of weaker floor.
- The struts should preferably be inclined at 45°. In no case should this inclination exceed 60°.
- Single shores should be used only up to 9 m distance between walls. For greater distance, double shores should be provided. In that case, both the horizontal shores should be symmetrically placed with respect to the floor levels.
- The flying shores should be spaced at 3 to 4.5 m centers, along the two walls; and horizontal braces should be introduced between adjacent shores.
- In this system, various members of the shoring are determined by using large factor of safety because it is uncommon to assess the actual loads.
- When there is a structural gap between two building due to removal of old building then, flying shore are inserted and removed after construction of new structure.
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3.Dead or Vertical Shores
Dead shore is a shoring system inwhich a dead shore in the form of vertical member support horizontal needleswhich transfer the load of the wall, roofs and floors etc.
The needles transfer the load ofthe wall etc., to the dead shores.
This type of shoring is use for the following purposes:
- To rebuild the defective lower part of the wall.
- To rebuild or deepen the existing foundation.
- To make large opening in the existing wall atlower level for underpinning and such type of work.
First of all holes are made in the wall at calculated height. Then needles made of thick wood or steel sections are inserted into the holes and are supported on vertical posts or dead shores on both sides. This type of shoring system is keep away from the wall for easy to do repair work. Dead shores are supported and anchor on plates and folding wedges.
The following points are to be considered for vertical shore:
- The section of needle and dead shores should be perfect to transfer the load, which can estimate with a fair degree of accuracy.
- The needles are spaced at 1 to 2 meters. A minimum of three needles should be used for and opening.
- The needles should be suitably braced.
- Sometimes opening is made in an external wall, that case the length of the outer shores is longer than inner ones.
- The dead shores are stable and rest on sole plates. Folding wedges should be inserted between the two. It is preferable to use one single sole plate between dead shores in a raw.
- The floors should be suitably supported from inside.
- In case the external wall is week then dead shore is not provided, in that case raking shores are provided.
- After 7 days of completion of the work shoring is removed making sure that new work has gained sufficient strength. The new work should have proper strutting.
- The sequence of removal should be (i) needles, (ii) strutting from opening, (iii) floor strutting inside, and (iv)raking shore if any at the interval of 2 days.
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What is shoring for concrete? ›
Shoring in the context of formwork relates to the temporary propping to support both temporary construction loads including loads of wet concrete during the construction phase.What is shoring and its types? ›
Shoring is the practice of building a temporary structure to support an unsafe structure on construction and excavation sites. Professionals use shoring to fix unstable walls, demolish structures, change existing walls, construct new walls and repair cracked or broken walls or foundations.What is the basic types of shoring? ›
There are two basic types of shoring, timber and aluminum hydraulic.How do you shore a concrete slab? ›
Mud jacking can lift a settled concrete slab by pumping a grout through the concrete and pushing it up from below. The process is sometimes called “slab jacking” or “pressure grouting”. 1 to 1 5/8th inch diameter holes are drilled through the sunken concrete block/slab at strategic locations to maximize lift.What is the most common type of shoring? ›
One of the most common shoring techniques used today is called H or I-Beam shoring. Another name for this process is soldier pile wall shoring. With this method, prefabricated steel H or I sections are driven or slid and vibrated into holes in the ground.What is shoring in Masonry? ›
Shoring is the process of temporarily supporting a building, vessel, structure, or trench with shores (props) when in danger of collapse or during repairs or alterations.What is shoring used for? ›
shoring, form of prop or support, usually temporary, that is used during the repair or original construction of buildings and in excavations.What is the purpose of shoring in construction? ›
Shoring becomes crucial in retaining the earth, ground water and adjacent structure, thus ensuring efficient excavation and construction. It requires two important component of shoring system: Earth retention system (piles or wall) Support system (internal/ external bracing like rakers, structs and tiebacks)What is shoring used for excavation? ›
Shoring is the provision of a support system for trench faces used to prevent movement of soil, underground utilities, roadways, and foundations. Shoring or shielding is used when the location or depth of the cut makes sloping back to the maximum allowable slope impractical.What is shoring during excavation? ›
Shoring is a system that supports the sides or walls. Shoring requires installing aluminum, steel, or wood panels that are supported by screws or hydraulic jacks. Some systems can be installed without the workers entering the trench. This option provides additional safety for those workers.
What depth do you need shoring? ›
Trenches 5 feet (1.5 meters) deep or greater require a protective system unless the excavation is made entirely in stable rock. If less than 5 feet deep, a competent person may determine that a protective system is not required.How do you support a sinking concrete slab? ›
You have three options: coat the sunken section with a sand-and-cement mixture to make the surface higher, raise the sunken section using a process called mudjacking, or raise the sunken section using expanding polyurethane foam.What do you put under a concrete slab? ›
Most concrete contractors want a mix of coarse and fine aggregate to create a compactable base that is going to be safe for settlement and drainage. Crusher run (a mix of crushed stone and stone dust) and #57 coarse aggregate are two of the best base materials for concrete slabs.What is the difference between formwork and shoring? ›
"formwork" means a system of forms connected together; "shoring" means the structural supports and bracing used to support all or part of a form. (2) An employer shall ensure that formwork and shoring are designed by an engineer and are erected in accordance with design drawings prepared by the engineer.Why is it called shoring? ›
Simply put, shoring is a supporting structure that's used during the construction or repair of buildings and other structures to prevent collapse. The term shoring comes from the word shore, meaning a timber or metal prop.How deep can excavation be without shoring? ›
How deep can a trench be without shoring? The Construction (Working Places) Regulations 1966 specified that any excavation exceeding a depth of 1.2m is the point where a shoring system should be in place.Is shoring better than trenching? ›
Shoring is the most economical and safest method of protecting trench workers. Cave-ins are the biggest hazard faced by the trench workers. An unstable trench can collapse and kill or injure the workers at any time. So it is essential to have a suitable protective system in place.At what depth is shoring required? ›
Trenches 5 feet (1.5 meters) deep or greater require a protective system unless the excavation is made entirely in stable rock. If less than 5 feet deep, a competent person may determine that a protective system is not required.Where is shoring required? ›
Shoring is Used to Enlarge Walls
Knit walls that need enlargement need to be supported; installing shoring is an ideal way to do that. It makes it easier for openings to be made or enlarged on the wall.
shoring, form of prop or support, usually temporary, that is used during the repair or original construction of buildings and in excavations. Temporary support may be required, for example, to relieve the load on a masonry wall while it is repaired or reinforced.
Is shoring done before excavation? ›
Wherever possible, install the shoring equipment as the excavation proceeds. If there is any delay between digging and shoring, no one should enter the unprotected trench. Trench Boxes are commonly used in open areas that are away from utilities, roadways, and foundations.How should shoring be installed? ›
All shoring should be installed from the top down and removed from the bottom up. Hydraulic shoring should be checked at least once per shift for leaking hoses and/or cylinders, broken connections, cracked nipples, bent bases, and any other damaged or defective parts.Where is shoring used in construction? ›
Shoring is the installation of vertical bending members and/or horizontal tie backs for the purposes of securing a wall face to allow for excavation to the desired depth.What is shoring in excavation? ›
Shoring is the provision of using a support system for trench faces which prevents movement of soil, underground utilities, roadways, and foundations. Each method has its own particular advantages and disadvantages, however hydraulic tends to be preferred because it is the safer option.