Ground water flow into excavations constructed by sheet pile walls should be minimized in order to save the cost of the provision of pumping systems or well points to lower the water table inside the excavation. In case a layer of impermeable material like clay is located slightly below the excavation, it may be desirable to drive the sheet piles further into this layer and the cost of further driving may be less than the cost of the provision of continuous pumping in the excavation. On the other hand, if there is no impermeable layer beneath the excavation, engineers may consider driving the sheet piles further so as to increase the flow path of groundwater into the excavation and this helps to reduce the amount of water flow into the excavation. Similarly, a cost benefit analysis has to be carried out to compare the extra cost of driving further the sheet piles with the reduced pumping costs.
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Showing posts with label Design of foundations for building. Show all posts
Showing posts with label Design of foundations for building. Show all posts
Design of foundations for building
Depth of Foundation :
Minimum depth of foundation is given by: H=P/W(1-Sinᶲ/1+Sinᶲ)
Ranking formula applicable to loose soils.
Where H= Depth of foundation in m Below ground level.
P= Safe permissible pressure on base in kg/sq.m
W= Weight of soil in kg/cu.m
ᶲ = Angle of response of soil material.
for tall structure such as chimneys and towers 3/4th of safe load om the soil should be taken and the depth h increased by 1/3 .
foundations are generally taken down to about 90 to 120 Cm for main walls 45 to 60 Cm for partition walls and 30 cm for boundary walls in ordinary soil 2 to 3 story building weight . But foundation must be taken down to a firm soil and below weathering effects . when part of a footing is in weaker soil , that part should be take down deeper and separated , or measures adopted for equal distribution of pressures according to the bearing capacity if the respective soils.
Minimum depth of foundation is given by: H=P/W(1-Sinᶲ/1+Sinᶲ)
Ranking formula applicable to loose soils.
Where H= Depth of foundation in m Below ground level.
P= Safe permissible pressure on base in kg/sq.m
W= Weight of soil in kg/cu.m
ᶲ = Angle of response of soil material.
for tall structure such as chimneys and towers 3/4th of safe load om the soil should be taken and the depth h increased by 1/3 .
foundations are generally taken down to about 90 to 120 Cm for main walls 45 to 60 Cm for partition walls and 30 cm for boundary walls in ordinary soil 2 to 3 story building weight . But foundation must be taken down to a firm soil and below weathering effects . when part of a footing is in weaker soil , that part should be take down deeper and separated , or measures adopted for equal distribution of pressures according to the bearing capacity if the respective soils.
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