Pipe Jacking – Manshield

Overview

Pipe Jacking is a trenchless technology used to install prefabricated pipes beneath the ground with minimal surface disruption. This method employs a tunnel boring machine (TBM) and hydraulic jacks to advance the pipe sections through the earth.

Key Applications

Pipe Jacking is an effective alternative to open-cut excavation, commonly used for:

• Crossing beneath roads, railways and rivers
• Navigating under canals, buildings and airfields
• Projects where avoiding traffic disruption is critical

Process

1. Shaft Construction

• Drive shaft (launch pit) and reception shaft are constructed at the pipeline’s start and end points.
• Shaft size varies based on excavation requirements.

2. Shield Launch and Pipe Installation

• A shield is launched from the drive shaft, creating a bore as it advances.
• Pipes are jacked into place directly behind the shield using hydraulic jacks.
• A thrust wall and thrust ring distribute jacking forces evenly.

3. Pipe Alignment

• Guide rails and steerable shields ensure correct alignment.
• Short pipelines use traditional surveying equipment for alignment checks.

4. Completion

• Upon finishing, the shield is removed from the reception pit, and the pipeline installation is finalized.

Ground Treatment Techniques

To minimize ground settlement risks during pipe jacking, the following techniques may be applied:

• Jet Grouting: Strengthens and stabilizes ground conditions.
• Silica/Cement Grouting: Reduces ground permeability and settlement.
• Dewatering: Controls groundwater levels during excavation.
• Ground Freezing: Temporarily solidifies the soil for stability.