Frequently Asked Questions

A pile foundation is a deep foundation that uses thin pillars under the ground for stability. It is typically long and made up of steel or concrete. It provides support for transferring weight to deeper layers of soil. Pile foundations are also used for high-rise buildings where the entire weight is concentrated in one precise area.

Pile foundation helps transfer the structure’s weight to stronger soil layers. and is a type of deep foundation. Large construction projects like bridges and buildings use pile foundations

• Pile foundations help transfer the building loads to a more stable soil found below several layers. It provides stability in sites that have weak upper layers of soil.
• Pile foundations are resistant to weathering, decay, and corrosion. Therefore, they are highly durable.
• It requires less space when compared to other foundation types, due to slender and long foundation elements.
• It can be customized based on the project requirements and can be constructed in different sizes and materials.
• They are effectively used in areas where deep installations are required, especially wetlands. Pile foundations help in preventing uplift in structures.
• It minimizes vibrations and also prevents soil erosion around the foundation.
• Pile foundations are cost-effective and can be quickly installed. It helps speed up the construction process.
• It has less environmental impact compared to other foundations

Here are some of the following situations, where using pile foundation system can be beneficial:

• When the groundwater table is high foundation pilings are the best solution
• Heavy and un-uniform loads from the superstructure are imposed
• Other types of foundations are costlier or not feasible
• When the soil at shallow depth is compressible
• When there is the possibility of scouring, due to its location near the river bed or seashore, etc.
• When there is a canal or deep drainage system near the structure
• When soil excavation is not possible up to the desired depth due to poor soil conditions
• When it becomes impossible to keep the foundation trenches dry by pumping or by any other measure due to heavy inflow of seepage

Whenever one of the above conditions occurs (where pile foundations are suitable for), the foundation engineer has to choose a foundation for the structure among different types of pile foundations.

Types based on function:

1. Sheet Pile
2. Load bearing Pile
3. End-bearing Pile
4. Friction Pile
5. Soil Compactor Piles

Types based on material and Construction Method:

1. Timber Pile
2. Concrete Pile
3. Steel Pile
4. Composite Pile

The limit of foundation piles depends on various factors including the soil conditions, load requirements, and design specifications. Typically, the number of piles required is determined based on:

• Load-Bearing Capacity: The size and number of piles must support the structural loads of the building.
• Soil Properties: Soil strength and load-bearing capacity influence the type and number of piles.
• Design and Code Requirements: Engineering standards and local building codes specify pile design and spacing.

An RCC pile foundation is a type of deep foundation where piles are made from Reinforced Cement Concrete (RCC). These piles are used to transfer the load of a structure to deeper, more stable soil layers or rock. RCC piles are reinforced with steel bars to enhance their strength and load-bearing capacity.

They are typically used in situations where surface soil conditions are inadequate for supporting structures, such as in areas with weak or compressible soil.

The minimum depth of a pile foundation generally starts at 5 to 10 meters (approximately 16 to 33 feet), but this can vary based on factors such as soil conditions, load requirements, and local building codes.

The actual depth is determined by a geotechnical engineer, who assesses the soil profile and structural loads to ensure the pile foundation reaches a stable layer capable of supporting the building’s load effectively.

There are several types of pile foundation available to use for a particular project. Few factors influence the selection of a particular type of pile foundation. These factors are noted below:

• Type and loads from the superstructure
• Properties of soil
• The depth of the soil layer capable of supporting the piles
• Variations in length of pile required
• Availability of materials
• Durability required
• Available equipment for pile driving
• Budget
• The depth of water level and intensity of underground water flow
• Types of surrounding structures

Pile foundation is one of the most popular choices for heavy loaded structures and in cases where poor soil conditions are found at a shallow depth. But pile foundations may fail due to different reasons.

One must take proper precautions before designing pile foundations so that the possibility of such failure reduces. Causes of failure of pile foundation are given below:

• Load implied on the pile is greater than designed load
• Defecting workmanship
• Dislocation of reinforcement of pile
• End bearing pile resting on soft strata
• Faulty soil investigation
• Selecting the wrong type of pile
• Under-reinforcement of the pile
• A decay of piles. (like attack of insects, corrosion etc.)
• Deformation of piles due to lateral loads
• Incorrect assessment of pile capacity
• Not considering lateral forces for designing of piles.

Shallow foundation and deep foundation have several differences. Sources of main differences between deep and shallow footings are definition, depth of foundation, cost, feasibility mechanism of load transfer, advantages, disadvantages, types, etc.

The table gives the main differences between shallow and deep foundations:

• Talk to your neighbors: Talk to your neighbors about the success and failure stories of borewell drilling in your locality.
• Depth of Water Source Availability: A geologist can help you to estimate the depth of the water source. However, we recommend that you talk to your neighbors to know the depth at which they receive the water. By doing that, you have the second source of information that relates to the depth of the water source and it must match with the input of your geologist.
• Rock availability: As mentioned above, the information gathered from both the localities and geologists will provide information about the presence of hard rock at the expected depth of the water source. This will also affect your budget and expenses.
• Approval for borewell: Before digging a well, you must first obtain a permit from the relevant authority. You need an approval letter from the local council and also a NOC (No Objection Certificate) from the nearest neighbor. The digging process must be carried out on the date and time approved by the local government.
• Borewell vendors: Always choose vendors that operate near the area. You can also consult the contractor to see if there is a reliable vendor. Before making a final decision, compare costs and quotes with at least 2-3 vendors. You can also instruct your vendor to use hydraulic equipment for faster execution.

• Government-approved Borewell contractors: Always look for government-approved.
• Borewell drilling contractors: These contractors have years of drilling experience and have handled many customers during borewell drilling.
• Groundwater survey service: Borewell digging begins with finding the right source of groundwater. Only professional geologists can conduct geophysical / groundwater surveys and find the correct drilling points, giving a continuous supply of groundwater.
• Experienced borewell contractors – The drilling contractor must have local geological experience and knowledge. Officials/supervisors should work with contractors to inspect existing wells in the area, as it provides important information on typical flow rates and water quality, permeating aquifers, borewell design, and construction trends, previous success rate perforation.
• Use of the latest equipment: Look for borewell drilling rigs with the latest advancements in drilling technology. The high-performance sensor equipment can easily find the underground water source, and has high accuracy in the excavation of the borewell, and can drill new borewells in bad weather.

Borewells are also classified according to their performance:

• High-performance wells (HCB): Wells with 10″ or 12″ casing and> 80 m depth, with a design rate between 20,000 and 45,000 GPH.
• Medium-sized production well (MCB): 8-inch case hole> 80 m deep, with a design capacity of 10,000 GPH to 20,000 GPH.
• Small Volume Borehole (LCB): A casing hole with a diameter of 6 inches and a depth of 30 to 50 meters, with a rated value of 1,500 to 5,000 g/hr.

Borewell contractors charge per feet based on the following factors:

• Borehole drilling cost
• Cost of the casing pipe cost
• Pipe installation
• Flushing and cleaning cost (after the drilling work)
• Transportation cost to bring borewell machine rigs to the borewell site

If the house is built on an ordinary foundation, it is usually recommended to build a well near the house. The shock waves generated during drilling are distributed on the ground and rocks. However, if you plan to drill a borewell near a large building that can withstand heavy loads, it is best to check the stability of the foundation.