Full-Length Pipe Construction Method: Comprehensive Pipe Construction Equipment Overview

In pile foundation engineering, the application of full-length pipe construction has expanded rapidly to meet the stringent demands of pile formation. Central to this approach is the selection of high-quality pipe casings, with LIMTA-manufactured casings being the preferred choice for their superior quality. Beyond the casings, what other equipment constitutes a full-length pipe construction setup? This article aims to introduce and share insights into the essential machinery involved.

1. Pipe Casing Driver

1.1 Overview

The pipe casing driver, or simply the driver, is a versatile tool designed to drive casings into the ground. It consists of a swivel joint and a driving auger (referred to as the auger). Some manufacturers integrate the swivel joint with the power head, simplifying the design while maintaining the same operating principle. The driver relies on the torque and thrust provided by the rotary drilling rig to sink the casing, with the swivel joint connecting to the power head above and the auger to the casing below. It allows concurrent drilling and soil excavation without interference, enhancing efficiency in short pile and small diameter applications. However, its effectiveness may be limited in deep or large diameter piles due to torque and thrust constraints, and verticality is generally average.

1.2 Specific Workflow

• Assemble the swivel joint and auger by aligning key slots and bolting them securely; connect the two with a pin.
• Hoist the first section of casing using a crane and align the auger with it using a loader or excavator.
• Align the casing center with the pile marker, retract the mast, adjust for verticality, and start sinking the first casing segment.
• Continue adding and aligning subsequent casing sections, sinking each as necessary.

2. Pipe Thruster

2.1 Overview

A pipe thruster is an auxiliary device used in unstable ground conditions to assist in casing insertion and extraction during旋挖钻机 operations. Available in two hydraulic drive modes—either connected directly to the drill rig's hydraulic system or powered by a separate hydraulic station—the thruster provides significantly greater torque and thrust compared to a drill rig, facilitating deeper and larger diameter casings than a pipe casing driver. The SCG150 model developed by SANY, for instance, delivers ten times the torque and thrust of a standard drill rig, outperforming foreign brands with its higher torque, pressure, and speed. However, it operates at a limited angle (25°), sinks casings slowly, and lacks a built-in vertical alignment mechanism, necessitating external aids for accurate placement.

2.2 Specific Workflow

• Lay steel plates or compact the loose surface to prevent ground collapse during casing extraction.
• Deploy the first casing section using a pipe casing driver (if available) or directly with the pipe thruster, ensuring the casing is correctly positioned and pressed down using its weight or a lifting cylinder.

3. Vibratory Hammer

3.1 Overview

Vibratory hammers are recognized as the most mature and efficient method for full-length pipe installation. They work in tandem with crawler cranes and can accommodate casings of various diameters, making them ideal for challenging soil conditions such as deep soft clay, sandy soil, and fine gravel layers. Despite their high efficiency, they face limitations in coarse gravel and heavily filled areas and lack precision for certain types of pile installations.

3.2 Specific Workflow

• Lower the first casing section with the vibratory hammer, connecting it to the casing shoe, and sink until 40-60cm above ground level.
• Repeat the process for additional casing sections, ensuring proper alignment and connection.

4. Pipe Extractor

4.1 Overview

Pipe extractors are primarily used in conjunction with pipe casing drivers when extraction capacity is insufficient. They operate similarly to pipe thrusters, clamping the casing and extracting it using lifting cylinders. Models like the L15 from Langfang Exploration Technology Institute are more affordable alternatives, capable of extracting casings up to 1.5 meters in diameter.

4.2 Specific Workflow

• Stabilize the ground, position the extractor, secure the first casing, and begin extraction, ideally during concrete pouring to reduce resistance.

5. Full Rotary Drill Rig

5.1 Overview

Full rotary drill rigs, prevalent in Japan, Taiwan, and Hong Kong, are adaptable to a wide range of geologies and engineering needs. They facilitate drilling, casing insertion, and extraction in complex ground conditions, including rock and karst formations. These rigs, however, are bulky, expensive, and produced predominantly by Japanese manufacturers.

5.2 Specific Workflow

• Align the full rotary rig and the drilling rig, sink the first casing using a pipe casing driver, and proceed with drilling and casing installation.

6. Dual-Power Head Multi-Function Drill Rig

6.1 Overview

Produced by LIMTA, this rig is designed for simultaneous drilling and casing insertion, suitable for challenging terrain like gravel and hard rock layers. It offers multi-functional operation with minimal environmental impact, addressing the challenges of large diameter and high-efficiency drilling in rocky conditions.

6.2 Specific Workflow

• Utilize specially fabricated casings, typically 6m in length, welding joints as needed, and follow similar procedures for casing installation as with a standard drill rig.

Each of these pieces of equipment plays a crucial role in the comprehensive full-length pipe construction methodology, offering tailored solutions for various project requirements and ground conditions.