safetycultureinfo

There  are two type of benching ,simple and multiple.The type of soil determines the horizontal to vertical ratio of the benched side.As a generlal rule the bottom  vertical heightr.. of the trench must not exceed  4 feet for the first trench.Subsequent benches may be up to a maximum of 5 feet vertical in type.A soil and 4 feet in type  b soil to a total trench depth of 20 feet .All subsequent benches must be below the maximum allowable slope for that soil type .For type B soil the trench excavation is permitted in cohesive siol.                                                                          ...

In order to carryout the excavation work safety and to minimise the risk .the following factors shall be concidered before the excavation starts. Size and purpose of excavation. Nature of the ground including the proximityof made up ground. Stability of adjuscent structures.Position of underground obstructions such as pipes ,electric cables and other utilities. Position of structures of archieological and historical interest. wether and moisture conditions high water table. Sourse of soil vibration (high way traffic,mechinery etc.) Adjucent road and fott path. Method of excavation.

Slopping is method of excavation in which the sides of  an excavation are laid back to safe angle to prevent cave ins. Trench boxes are generally used in open  areas but they also may be used in combination with slopping and benching.The boxes should extend atleast 18 inches above the surrounding area, if there is slopping towards excavation.This can be accomplished by providing a benched are adjusted to the box.Earth excavation to a depth of 2 feet below the shield is permitted.

Shielding with a trench box can protect the workers in a trench from cave in.Trench box are different from shoring. Instead  of shoring up or otherwise supporting the trench face ,They are intended primarily to shield workers from cave in and similar incidents.The excavated area beet ween the out side of the trench box and  the face of the trench should be as small as possible.The space between    trench box and the excavation side are back filled to prevent  lateral movement of the box.Shields may not be subjected to load exceeding those which the system was designed to withstand.

Shoring is the provision of support system for trench faces used to prevent movement of soil.,under ground utilities,road ways and foundations.Shoring is used when the location or depth of the cut makes,slopping back to the maximum allowable slope-impractical. Shoring system consist of posts, wale  , straits and sheeting.  Three basic type of shoring's are :  Timber.  Hydrolic.  Pneumatic.

Different protective systems are used in excavation to prevent any accident like cave in using different systems for excavation can be called as a method of excavation.They are ; shielding ,sloping ,shoring ,benching.the determination of angle of slopes ,benches or the choice and design of other protective systems shall be based on the evaluation of pertinent factors such as : type of soil,depth of excavation, possible variations in water content of the materiel while the excavation is open.Anticipated changes in materiel from the exposure to air,sun or water.Loading imposed by structures,equipment,overlying material or stored material ,vibration  from the equipment ,blasting, traffic-or other sources.

Just look forward; What are you see now, Where is the beginning ,Let start our safety from there.