Ø Basement construction method
The build of basement is tough for it must be passed below ground in opposing condition such as existence of ground water, muddiness or restricted working space. Also, works are needed to be done among layers of props, struts, walings and shores, which cannot be detached until the permanent works is finished and capable of carrying the final loads. For each circumstance of the basement build, the method of soil support, sub-soil condition, structure of the basement among the layout condition of the entire building must be taken into thought before designing the method of works.
Method of constructing the basement
One of the most operative approaches to construct a basement is by the use of diaphragm wall or sheet pile wall (cut-off) which functions as a retaining structure through excavation and as the sides of the basement walls. Once has the central soil removed throughout excavation, the cut- off wall must be properly braced for works.
Ø Dewatering system
Ground water is water which is detained in soil, either in a non-saturated, saturated or over- saturated form. Water in soil frequently performances as a lubricant, which rise the tendency of soil to slip or slide. Besides, it sources certain complications and danger in case of excavations to be done.
Keeping out of ground water
Ground water can be held out either permanently such as for long period of time waterproofing for a basement, or temporarily such as to ease work during excavation.
The following requirements can supply certain degree of water-tightness to the basement throughout the construction:
1. Sheet piling
2. Diaphragm walls
3. Suitable grouting to the sub-soil
Also, ground water can be furthermore control by the use of the following arrangement:
1. Sump pumping
2. Well point systems
3. Shallow or deep-bored wells
4. Horizontal ground water control
5. electro-osmosis method
Ø waterproofing system
Waterproofing the basement
A water-tighted basement wall is a vital element to a watertight basement. Though, due to the basement walls are frequently built under complex phases to match with the excavation arrangements and this may rise the risk of leaking, therefore, cautious structure joining design is vital to make sure the basement structure is seamlessly water- proved.
The most widely used process to water-proof a basement is to deliver a cavity to the wall of the basement (by constructing a skin wall to the sides).
Grouting Grouting is frequently used to stop the flow of water in sub-soil with high absorptivity, such as in fissured and linked rock strata. Row/s of holes are bored on the soil and, frequently cement grout, are added under high pressure. The cement grout will enter into the spaces of the sub-soil and form rather a waterproof curtain sheer separating the ground water.