What is a Bored Pile? The Ultimate Guide for Homeowners and Contractors

What is a Bored Pile? How does it differ from Driven Piles?

A Bored Pile is a cast-in-place reinforced concrete pile constructed by drilling a hole in the ground to a specified depth, installing a steel reinforcement cage, and pouring concrete into the hole. It differs from a driven pile, which is precast at a factory and hammered into the ground using a pile driver.

The most significant difference is **vibration**. Bored piles produce minimal vibration and noise, making them highly preferred in urban areas, densely populated neighborhoods, or when extending houses near existing structures to prevent structural cracking.

Types of Bored Piles

Bored piles can be categorized by working methods and soil conditions into two main systems:

• 1. Dry Process Bored Pile: Drilled using a tripod rig without water or chemicals to support the hole walls. It is suitable for cohesive clay that resists collapse. Typically used for pile diameters of 35 - 60 cm, with depths not exceeding the first sand layer (approx. 20-30 meters).
• 2. Wet Process Bored Pile: Uses large machinery for deep drilling and introduces a polymer or bentonite slurry into the hole to support the soil walls and prevent collapse. Suitable for high-rise buildings, condominiums, or bridges requiring large piles and deep drilling through sand layers.

5 Benefits of Bored Piles in Modern Construction

• 1. Vibration-Free: Friendly to neighbors, preventing house cracking and building settlement caused by pile driving.
• 2. Works in Tight Spaces: The tripod rig for dry process is compact and can operate well in narrow alleys or areas with limited headroom. Check clearance requirements with our tool.
• 3. Adjustable Depth: If hard stratum is encountered earlier than planned, drilling can stop and concrete can be poured, ensuring precise load-bearing capacity. Check soil depth guides here.
• 4. No Soil Heaving: Driven piles displace soil upwards, but bored piles remove soil, keeping surrounding ground levels unchanged.
• 5. High Load Capacity: A 60 cm bored pile can safely support 70-80 tons, sufficient for commercial buildings and factories. Calculate pile capacity here.

Standard Dry Process Bored Pile Installation Steps

Bored piling requires expertise and strict standards to prevent pile failure or soil collapse. The steps are:

• 1. Layout and Centering: Marking the drilling points according to the plan.
• 2. Temporary Casing Installation: Driving a 12-15 meter steel casing to prevent soft soil from collapsing into the hole.
• 3. Drilling: Using a bucket auger to remove soil until reaching hard clay or sand layers.
• 4. Rebar Cage Insertion: Lowering the pre-tied rebar cage into the hole with concrete spacers (covering) to maintain concrete cover distance.
• 5. Concrete Pouring: Pouring concrete through a tremie pipe to the bottom of the hole to prevent segregation.
• 6. Casing Extraction: Withdrawing the casing simultaneously with concrete pouring and trimming the pile head to the desired level.

Pile Integrity Testing (Seismic Integrity Test)

Since bored piles are cast underground, visual inspection of the concrete integrity is impossible. Therefore, a Seismic Integrity Test according to ASTM D5882 is essential.

The method involves striking the pile head with a handheld hammer and measuring the reflected wave with a sensor. A uniform graph indicates an intact pile without necking, bulging, or soil inclusions. Tawanchai Khemjoh Co., Ltd. provides Seismic Testing services by expert engineers for 100% confidence.

Conclusion: Are Bored Piles Worth It?

Although bored piles are generally more expensive than driven piles, considering the safety benefits, avoidance of neighbor disputes, and tight-space capabilities, bored piles are a highly worthwhile investment that prevents long-term headaches.

If you are looking for a standard-compliant dry process bored pile contractor with over 20 years of experience, contact Tawanchai Khemjoh Co., Ltd. today. We offer free consultation and estimates!