Week 7 Challenge

1 :- Piles are the structural component which comes under the deep foundation, The function of the pile is to transmit a load of a structure to competent sub-surface strata by the resistance develop from bearing at the toe or skin friction along the surface of both. piles also carry uplift pressure and lateral load.

No of piles that are required in deep foundation is calculated by using the below formula,

Number of piles = Safe bearing capacity of soil/pile capacity.

Where,

Safe bearing cpacity (SBC) which is carrying maximum pressure that soil can carry safely without risk of shear failure. and it is calculated after geotechnical investigation.

Lateral load capacity of a single pile depends on the soil reaction developed and the structural capacity of the shaft under bending. pile capacity depend also on soil property. and other factor like type of soil present in that loacation. ( All the important consideration for finding pile capacity is refering from IS 2911 code ).

Following are the loads which is acting on the structure.

1. Dead load
2. SIDL
3. Vehicular Live Load.
4. Breaking Force.
5. Live Load surcharge.
6. Earth pressure (In abutment)
7. Water Current Load.
8. Wind Load.
9. Temperature Load.
10. Earth quake load.

And all the load combination done using ULS and SLS method referring from IRC 6.

ULS combination.

SLS Rare & Combination.

Following are the factor which impact the number of piles and its depth.

1. Safe bearing capacity of soil and and pile capacity.
2. Property of soil in that location.
3. Spacing in piles and diameter of piles.
4. Settlement occurs in pile group.
5. Load from superstructure
6. Material availabe on site

For the abutment overturing factor is there due to earth pressure load for that no of piles is required more as compare to pier.

Aim :- How to fix the diameter of well in the deep foundation in a river bridge in Delhi, listing all the loads acting on it and making all the combinations as per IRC 6.

What are the different factors that can impact the diameter of well and its depth.

how it is different in wall type abutment , fixed and free pier.

Answer :- Well foundation is a type of deep foundation which is generally provided below the water level for bridges. many factor which decide the diameter of well foundation in river bridges i.e. Property of soil, mean velocity of water flowing in the river, base pressure, uplift pressure etc. many limiting value is given in the code such as minimum dimension of dredge-hole shall not be less than 3 M. and external diameter of singular circular not exceeds 12 M.

Following are the loads which is acting on the structure.

1. Dead load
2. SIDL
3. Vehicular Live Load.
4. Breaking Force.
5. Live Load surcharge.
6. Earth pressure (In abutment)
7. Water Current Load.
8. Wind Load.
9. Temperature Load.
10. Earth quake load.

And all the load combination done using ULS and SLS method referring from IRC 6.

ULS combination.

SLS Rare & Combination.

Following are the factor which impacting the diameter of well and its depth.

• Property of soil.
• Sinking process.
• While sinking whole well inside the ground it may be tilt, that measures we may be take.
• Depth of water
• Scouring zone

Aim :- What is free standing length in a pile system and how to determine this.

Also list all the applicable code clauses from IRC and IS codes.

Answer :- The lenght of piles which is coming under scour depth and liquification zone is known as free standing length in pile system. piles under scouring and liquification is important criteria consider for designing the pile foundation.For free standing lenght we have to worry by taking different criteria like providing Liner in that lenght.

Codes which is use to design and contruction process of pile are IRC 78, IS 2911

Imp clauses we is use in Code are.

In IRC 78: Clause no 703 (discharge and depth of scouring for foundation desing.) is use to find free standing lenght in pile system.

Clause no 706 for loads, forces, stability and stress in foundation design.

Clause no 708 for detail about well foundation.

Clause no 709 for detail about Pile foundation.

IS 2911 code is all about pile foundation design and construction.

Aim :- What will be the impact of free-standing length on the full length of the pile.

Roughly determine no. of piles on abutment of height 5 m and width of 12 m.

Vertical capacity – 250 tonnes

Horizontal capacity-35 tonnes

Answer :- If the free standing lenght is increase then the height of piles aslo increase. we have to provide height of pile including free standing length.pile surface may expose to open surface due to which economy cost of pile also increase and environment impact also happen in pile. For that we have to maintain the structure regularly.

Given data :-

• Height of abutment = 5 M
• Wight of abutment = 12 M
• Vertical capacity = 250 tonnes
• Horizonatal capacity = 35 tones

To Calculate No of pile required in foundation.

Assuming total load from the structure is 2500 T

So,

= Total laod from structure / Veritical capacity.

= 2500 / 250

= 10 Nos of pile required.

Total piles requird in foundation is 10 Nos

Aim :- List out failures in deep foundations and their remedies as per the codal provisions.

What all construction parameters need to be taken care of before planning a deep foundation.

Answer :-

Following are failure in deep foundation and there remedies.

• Unequal settlement of the sub-soil
• Horizontal movement of the soil adjoining the structure.
• Tilt and tolerance failure.
• Lateral pressure tending to over- turn the structure
• lateral escape of the soil below the foundation
• Rcc failure.
• Buckling of piles.
• Breaking of piles.
• Tension failure of concrete pile for lack of reinforcemen.
• Disintegration of concrete due to poor quality of concrete or reactive aggregate.

Remedies to prevent failure of pile foundation:

• Early repair such as encasement or replacement
• Removal of partial load
• Underpinning

Construction parameter use in deep foundation.

• Protective works i.e. cofferdam, sheet pilling to be done around the foundation.
• Site clearence adn boring shall be done as per indian standerd.
• Lowering the steel cages after clearing.
• Casting the piles by pouring wet concrete.
• Bottom plug sink & top plugging in case of well.