What are ideal conditions for use of an end bearing pile?
What are ideal conditions for use of an end bearing pile?
The firm strata under weak soil layer should be reachable otherwise friction pile is recommended. When a building has considerably heavy concentrated loads. Large fluctuations in sub-soil water level. Canal or deep drainage lines exist near the foundations.
How does load is transmitted by pile in end bearing piles?
End bearing piles Load is transmitted to the soil through friction or cohesion. But sometimes, the soil surrounding the pile may adhere to the surface of the pile and causes “Negative Skin Friction” on the pile. Negative skin friction is caused by the drainage of the ground water and consolidation of the soil.
What are end bearing piles?
End-bearing piles develop most of their load-bearing capacity at the toe of the pile, bearing on a hard layer of rock or very dense soil and gravel. The pile transmits the load through soft, compressible strata directly onto firm strata. This type of pile therefore acts in the same way as a column.
What are end bearing piles and friction piles?
Friction piles are in contrast to end-bearing piles which develop most of their load-bearing capacity at the toe of the pile, bearing on a hard layer of rock or very dense soil and gravel.
How do you calculate the end bearing of a pile?
Step 2: compute the ultimate end bearing capacity (acting as individual piles). Ultimate end bearing capacity in clay = Nc × C × pile tip area (Nc = 9). Ultimate end bearing capacity in soft clay = 9 × 120 × π × diameter2/4 = 848.2 lbs/per pile. Total ultimate bearing capacity per pile = 76,920 + 848.2 = 77,768 lbs.
How do end bearing piles work?
End Bearing Piles In this type of pile, the bottom end of the pile rests on a strong layer of soil or rock. The loads from the superstructure are directly transferred to the hard soil through bearing action of the pile bottom tip. As a result, the pile acts as a column.
Are friction piles more effective than end bearing piles?
Friction piles are useful when the strong strata are very deep and it is becoming economically unfeasible to have end-bearing piles. In such cases, friction piles can effectively perform the function by resisting the acting load through the skin friction.
What is the effective length of pile?
The values of effective pile lengths are 69.70, 85.12, 74.32, and 71.65 m, respectively.
How do you calculate the structural capacity of a pile?
Structural Capacity Based on CP4 In CP4, structural capacity (working stress) of nominally reinforced bored piles is calculated using 0.25fcu (ultimate cube strength) but limited to a maximum of 1,088 psi (7.5 MPa).
How deep do piles need to be?
Piles were typically concrete, installed to a depth of 300 mm or more. Houses could be supported fully on piles, or have internal bearer support only provided by piles.
Why are friction piles used?
Friction pile is a kind of pile foundation. This type of pile utilizes the frictional resistance force between the pile surface and adjacent soil to transfer the superstructure load. For a stable foundation condition, the friction force must be adequate to support the superstructure. …
Where does the capacity of end bearing piles come from?
Pile capacity comes from skin friction and end bearing. Most engineers prefer to construct end-bearing piles, extended to the bedrock. This is the safest type of pile, since in most cases the bedrock is solid. The integrity of the bedrock should be confirmed through rock coring.
Why do you put a shoe on an end bearing pile?
Many of the formations that are suitable for end bearing are overlain by weathered zones, vary in elevation across the top of the stratum, or may have overlying inclusions such as cobbles or boulders and require a “driving shoe” be added to the tip to aid in preventing damage and penetrating through obstacles.
Can a timber pile be driven through hard ground?
Timber piles cannot be driven through hard ground. Steel “H” piles are essentially end-bearing piles. Due to a limited perimeter area, “H” piles cannot generate much frictional resistance. Corrosion is a major problem for steel “H” piles. The corrosion is controlled by adding copper into steel.
What kind of rock is an H pile used for?
H piles are normally used for end bearing in dense sand, hard clay, clay shale, or a hard rock formation.