Boring Square Holes for Square Piles: A Step-by-Step Guide 

 Step 1 – Casing Burial:   

The casing is initially buried through open excavation. A rectangular trench is excavated to a certain depth, after which a steel casing of square cross-section, matching the pile's diameter, is placed into the trench by an excavator. The position of the casing is carefully checked to ensure that the four corners are aligned correctly and the top is level. The casing is then backfilled with plain soil, compacted to secure its position and prevent any movement during construction. A safety fence is also installed around the casing for protection.

 Step 2 – Center Drilling:   

A conventional rotary drilling machine with a circular drill bit is used to drill and extract soil from the center of the square pile hole to a certain depth. To maintain the stability of the hole wall, it’s recommended to drill in stages, such as 10m at a time, rather than drilling directly to the design elevation. Excavators promptly transport the drilling slag to designated areas to keep the hole clear.

 Step 3 – Four Corners Trimming:   

The rotary drilling rig's control system is adjusted to ensure the drill rod remains vertical. A specialized drill bit with corner and edge cutters is then used to trim the four corners and edges of the square pile from top to bottom, guided by the steel casing. The trimming speed must be controlled to ensure consistent verticality and diameter.

 Step 4 – Hole Cleaning:   

A side drill bit is used to scrape any loose soil at the bottom of the hole, moving it toward the center of the pile. Then, a rotary drilling slag drill bit is employed to remove this soil, ensuring that the hole is thoroughly cleaned and the bottom is flat.

The process is repeated until the hole reaches the designed depth.

 Prefabricated Square Pile Installation Methods: 

1.  Hammering Method:   

Also known as pile driving, this method utilizes the impact energy from a falling pile hammer to overcome the soil resistance and drive the pile into the ground. This method is widely used for reinforced concrete precast piles and offers rapid construction with a high degree of mechanization. However, it can lead to soil squeezing, noise, and vibration, which are undesirable in certain environments. Equipment used includes pile hammers (drop hammers, air hammers, diesel hammers) and pile frames (rolling, track, or crawler frames), which guide and lift the pile for accurate placement.

2.  Vibration Method:   

In this method, the vibrating force from a vibrating pile sinker attached to the pile head reduces the friction between the pile and the surrounding soil, allowing the pile to sink under its own weight. The vibrating pile driver consists of an electric motor, a spring support, an eccentric vibrating block, and a pile cap. This method is particularly effective for soft soils or water-bearing sand layers. However, it can be challenging in gravel layers and may require water flushing for better results.

3.  Static Pressure Method:   

For soft soil foundations, this method uses a static pile driver or hydraulic press to drive the prefabricated piles into the ground without vibrations. This method is quieter and minimizes environmental disruption, making it ideal for sensitive areas. The process is carried out in sections, with each segment being driven in until the next section is connected.

 Differences Between Square and Round Piles: 

1.  Shape and Geometry: 

   -  Square Piles:  These piles have a square cross-section with flat sides.

   -  Round Piles:  These piles have a circular cross-section with a smooth, continuous curve.

2.  Load Distribution: 

   -  Square Piles:  Square piles offer better lateral contact with the soil, though their corners can lead to stress concentration, especially with eccentric or lateral loads.

   -  Round Piles:  Round piles distribute loads more evenly in all directions, making them more efficient for vertical load-bearing applications.

3.  Skin Friction: 

   -  Square Piles:  Square piles tend to have more skin friction due to the flat surfaces, but the friction is less uniform than in round piles because of the corners.

   -  Round Piles:  Round piles provide more uniform contact with the soil, making them more efficient for load transfer in softer soils.

4.  Construction and Installation: 

   -  Square Piles:  Square piles are easier to form, especially in confined spaces, and align more simply during installation.

   -  Round Piles:  Round piles require more precision during the forming process but provide smoother, more predictable installation.

5.  Soil Penetration: 

   -  Square Piles:  Square piles may encounter more resistance in dense soils due to their sharp edges, although they are more efficient at resisting lateral forces during installation.

   -  Round Piles:  Round piles typically penetrate more easily into dense soils but may not "bite" into hard layers as effectively as square piles.

6.  Bending and Lateral Loads: 

   -  Square Piles:  Square piles are better at resisting lateral loads and bending moments due to their sharp corners, making them suitable for structures subjected to lateral forces.

   -  Round Piles:  Round piles are less efficient at resisting lateral forces, but their smooth shape enhances their vertical load-bearing capacity.

7.  Cost and Construction Time: 

   -  Square Piles:  Square piles may be quicker and less expensive to cast because they require less precise forming. However, the cost difference is minimal unless a large number of piles are involved.

   -  Round Piles:  Round piles take more time to form but may be more cost-effective in specific conditions where smoother penetration is required.

8.  Aesthetic and Practical Considerations: 

   -  Square Piles:  Square piles may be preferred for aesthetic reasons or where they align with other structural elements of similar shape.

   -  Round Piles:  Round piles are typically less noticeable, making them ideal for projects where the piles are hidden or where large quantities of uniform piles are needed.

9.  Applications: 

   -  Square Piles:  Often used in applications involving lateral loads, bending, or shear forces, such as in bridges, retaining walls, or high-rise foundations.

   -  Round Piles:  More commonly used in vertical load applications like marine structures, tall buildings, and offshore foundations, or when high soil bearing capacity is required.

---

This version retains the original content, rewording it slightly to maintain a similar structure and word count while ensuring the technical details are preserved.