01.Under Reamed Piles:

The Solution for Expansive Soils

Under Reamed (UR) Piles are a specialized type of bored, cast-in-situ concrete pile designed primarily to provide a robust and reliable foundation in challenging ground conditions, particularly in areas with expansive soils like black cotton soil.

How They Work

The core feature of an Under Reamed Pile is its enlarged base bulb (or multiple bulbs) created at the bottom of the bore. This bulb is formed using a special tool called a reamer before the concrete is poured.

The pile functions in two critical ways:

• 1. Anchorage: The enlarged bulb acts as an anchor below the zone of seasonal moisture variation (the active zone). When expansive soil swells due to moisture, it grips the vertical shaft but cannot lift the pile because the bulb is locked into the non-expansive, deeper stratum.
• 2. Bearing Capacity: The bulb significantly increases the bearing area, distributing the structure's load over a much larger surface, thereby enhancing the overall load-carrying capacity of the foundation.

Key Advantages

• • Counteracts Swell and Shrink: The most significant advantage is their ability to resist the forces of uplift and heaving caused by the volume changes in expansive and cohesive soils, protecting the structure from differential settlement.
• • Increased Load Capacity: They offer higher compression and tension (uplift) capacity compared to a plain straight-shaft pile of the same diameter and depth.
• • Cost-Effective: Often a more economical foundation choice than deep straight-shaft piles or rafts when dealing with moderate to high expansive soil risks.

Under Reamed Piles are the geotechnical engineer's choice for providing stability and long-term durability in unpredictable sub-surface environments.

02.Bored Piles (Cast-in-situ Piles):

Flexible and Strong Foundations

Bored piles, also known as cast-in-situ piles, are deep foundation elements created by excavating a circular hole in the ground and then filling it with reinforced concrete. They are one of the most versatile and widely used deep foundation systems globally, capable of supporting extremely heavy loads.

The Installation Process

The process typically involves:

• 1. Drilling: A drilling rig (like a rotary rig) excavates the soil to the specified depth and diameter.
• 2. Stabilization: To prevent the collapse of the bore walls in unstable soil, temporary steel casings or stabilizing slurries (such as bentonite) are used.
• 3. Reinforcement: A pre-fabricated steel reinforcement cage is lowered into the hole.
• 4. Concreting: Concrete is placed using a tremie pipe from the bottom up, ensuring a dense, continuous, and void-free pile shaft as the casing or slurry is withdrawn.

Key Advantages

Bored piles offer significant benefits, making them suitable for complex urban projects:

• • High Load Capacity: They can be constructed to very large diameters and depths, offering superior vertical load-bearing capacity for tall buildings and heavy infrastructure.
• • Minimal Vibration: Since soil is removed rather than displaced (unlike driven piles), the installation causes minimal noise and ground vibration. This makes them ideal for use near existing structures, heritage buildings, or sensitive urban environments.
• • Adaptability: The length and diameter of the pile can be easily adjusted to suit changing ground conditions encountered during drilling, ensuring the pile tip is founded on the optimal bearing stratum.

Bored piles provide a secure, adaptable, and low-disturbance solution for ensuring the stability of critical structures.

03.Tractor Mounted Rig:

Power and Portability for Piling

The Tractor Mounted Rig (TMR) is a highly efficient and versatile piece of equipment designed for geotechnical drilling and deep foundation work.1 By integrating the drilling mast and power unit onto a modified agricultural tractor chassis, the TMR achieves an exceptional balance of power, mobility, and ease of operation.

Versatility in the Field

The TMR is specifically engineered for projects that demand frequent relocation and high adaptability:

• • Rapid Mobilization: Its inherent wheeled design allows the rig to be driven directly onto and around the job site without requiring specialized transportation trailers, significantly reducing mobilization time and cost.
• • Accessibility: It excels in medium to small-scale projects, rural locations, and sites where access might be tight or challenging for larger, dedicated piling rigs.
• • Flexibility: While commonly used for smaller Under Reamed Piles and Bored Piles, the rig's capabilities can be adapted for soil investigation, shallow drilling, and specialized tasks.

Key Operational Benefits

• • Cost-Effective: The relative simplicity and dual-purpose nature of the tractor base make the TMR a more economical solution for many smaller foundation projects compared to heavy dedicated rigs.
• • High Maneuverability: The tractor steering system provides superior maneuverability in congested or irregularly shaped construction sites.
• • Efficiency: Despite its size, modern TMRs are equipped with powerful hydraulic systems, ensuring effective drilling torque and pull-down force for efficient penetration through various soil strata.

The Tractor Mounted Rig is the ideal solution when your project requires a quick, agile, and powerful piling unit that can handle rapid deployment and challenging site logistics.

04.Touch Rig (Manual/Tripod Rig):

Precision in Confined Spaces

The Touch Rig, often referred to as a Manual Rig or Tripod Rig, represents a specialized approach to deep foundation drilling. Unlike large, automated machinery, the Touch Rig is a lightweight, non-self-propelled apparatus that utilizes a system of sheaves, wire ropes, and winches to perform the drilling and concreting operations. It is the essential tool for geotechnical work in the most challenging and sensitive environments.

Ideal for Restricted Access

The primary advantage of the Touch Rig lies in its minimal footprint and low-impact operation:

• • Confined Spaces: It can be disassembled, carried through narrow doorways, and quickly reassembled inside existing structures, basements, or congested urban sites where vehicular access is impossible.
• • Low Headroom: With adjustable mast heights, it is perfectly suited for drilling under existing canopies, power lines, or inside factory floors with limited overhead clearance.
• • Sensitive Environments: Because the drilling process is often slower and more controlled than mechanical methods, it generates minimal noise and virtually no ground vibration, making it the preferred choice next to heritage structures or occupied residential buildings.

Precision and Control

The manual operation allows the operator to have a direct 'feel' (hence the name 'Touch Rig') for the subsurface material. This tactile feedback is crucial for accurately identifying soft pockets, rock layers, and water tables, ensuring the pile is founded precisely on the correct bearing stratum.

When accessibility and environmental sensitivity are paramount, the Touch Rig provides a controlled, precise, and reliable foundation solution.

05.Driven Piles:

High-Capacity, Prefabricated Foundations

Driven piles are a deep foundation system where prefabricated pile elements are inserted into the ground using specialized impact or vibratory hammers.1 Unlike bored piles, driven piles are non-displacement piles, meaning they physically displace the soil as they are installed, leading to significant densification of the surrounding ground.

Installation and Types

The pile elements, which can be made of precast concrete, steel (H-piles or pipe piles), or timber, are hoisted and positioned vertically under the leads of a piling rig.2 The hammer then delivers repeated blows or high-frequency vibrations until the pile reaches the required depth or achieves a specific load-bearing resistance, often measured by the 'set' (the penetration distance per hammer blow).

This method is highly favored due to its inherent qualities:

• • Quality Control: Since the piles are manufactured off-site, their quality, material strength, and dimensions are strictly controlled before they arrive at the construction site.
• • High Load Capacity: The displacement of soil during driving increases the density and confining stress in the adjacent soil. This action significantly enhances the skin friction (side resistance) and end bearing, resulting in very high load-carrying capacity.

Advantages on Site

• • Speed of Installation: Once the rig is set up, the installation rate is very fast, making them ideal for large-scale infrastructure projects like marine jetties, bridges, and industrial plants.
• • Immediate Use: Driven piles can carry the structural load immediately upon installation, as no curing time for concrete is required.
• • In-situ Load Test: The driving criteria itself acts as a full-scale load test, offering immediate verification of the pile's capacity.

Driven piles offer a proven, powerful, and rapid solution for deep foundation requirements in various soil and environmental conditions.

06.Load Tests:

Verifying Foundation Strength

Load Tests are a critical component of geotechnical quality assurance, used to verify the actual load-carrying capacity and settlement performance of installed deep foundations, such as Bored, Driven, or Under Reamed Piles. These tests are essential to ensure the foundation meets the structural design requirements and provides the required factor of safety.

Types and Procedure

The most common types of load tests include:

• • Static Vertical Load Test: This is the most accurate method. A known, incremental load is applied to the pile head using a hydraulic jack, reacting against a heavy mass (like a reaction frame or anchor piles). Measurements of settlement are taken at each load increment. This continues until the pile fails or reaches a predefined safety load limit.
• • Dynamic Load Test (PDA): A rapid, high-strain test where a drop hammer delivers an impact load to the pile head. Sensors measure strain and acceleration, allowing engineers to calculate the pile's capacity using wave equation analysis.

Importance for Construction

Load testing provides crucial data that ensures the integrity and reliability of the entire structure:

• • Confirmation of Design: It confirms whether the installed pile can safely support the intended design load with acceptable settlement levels, especially important in variable or unexpected soil conditions.
• • Cost Optimization: If tests show the capacity is greater than initially calculated, it can sometimes allow for a reduction in the number or size of future piles, leading to significant project savings.
• • Compliance: Performing and documenting load tests is often a mandatory requirement by local building codes and engineering standards before construction can proceed.

By performing rigorous Load Tests, Astep Geotecs provides clients with absolute confidence in the stability and long-term performance of their foundation investment.