Project Case Study: AT-4000L Raise Boring Machine Completes a 3.5 m × 213.5 m Ventilation Shaft in Guinea

Project Location
Kindia Tunnel Project, Guinea, West Africa
Project Contractor: China Railway 18th Bureau Group
Project Type: Tunnel Ventilation Auxiliary Shaft Construction

Equipment Model
AT-4000L Raise Boring Machine
Developed by Hunan Yier Mining Technology

Technical Parameters

Shaft Diameter: 3.5 m

Shaft Depth: 213.5 m

Shaft Type:  1# Ventilation Auxiliary Shaft

Drilling Operations: Pilot-Hole Drilling and Reaming

Rock Conditions: Challenging geological conditions;

Project Challenges

Remote project location with difficult equipment transportation and mobilization

Challenging underground construction and site conditions

Strict shaft alignment and drilling deviation control requirements

Demanding pilot-hole drilling and reaming operations

Limited access to spare parts and maintenance resources in a remote location

Solution and Results

Stable Equipment Positioning: A reinforced shaft collar construction and slope protection plan was jointly developed by the contractor, design institute, and Yier Mining team. The shaft collar thickness was increased from 2 m to 6 m, with the structure fully filled with concrete to provide a stable foundation.

Precision Pilot-Hole Drilling: The AT-4000L's automatic anti-stalling and deep-hole deviation control systems helped maintain stable drilling parameters and control pilot-hole deviation.​​​​​​​

Controlled Reaming Operations: Yier Mining's on-site service engineer monitored drilling parameters and rock discharge conditions to support smooth and controlled reaming.​​​​​​​

Successful Shaft Breakthrough: The machine successfully completed the 3.5 m-diameter, 213.5 m-deep ventilation auxiliary shaft, meeting the project's design requirements for construction quality.​​​​​​​

Localized After-Sales Support: Yier Mining established a spare parts inventory in Guinea and provided coordinated on-site and online technical support to help reduce potential equipment downtime.

Customer Feedback
The project team recognized the on-site technical support provided by Yier Mining's after-sales engineer. Representatives from the China Railway Guinea project team visited the site to witness the successful shaft breakthrough.​​​​​​​

Key Takeaway
The Kindia Tunnel Project demonstrates the AT-4000L Raise Boring Machine's capability to complete large-diameter, deep ventilation shaft construction under challenging international project conditions, supported by professional engineering assistance and localized after-sales service.