Micro-tunneling A Comprehensive Guide and Case Studies from Encardio Rite’s Global Experience

Micro-tunneling is a non-disruptive tunneling technique used primarily for the installation of pipelines beneath highways, railroads, rivers, and other sensitive areas without the need for open trench methods. This trenchless technology is designed to provide precise line and grade in various soil conditions, including those with high groundwater pressures. The method involves the use of a remotely controlled Micro-tunnel Boring Machine (MTBM) coupled with a pipe jacking technique to directly install product pipes.


How Micro-tunneling Works?

The micro-tunneling process begins with a launch shaft at the tunnel's designated starting point. The MTBM is then lowered into the shaft and launched through the ground. It is controlled remotely from the surface, where operators monitor its progress and adjust its path as necessary. As the machine excavates the tunnel, pipes are pushed behind it from the jacking station in the launch shaft. Upon reaching the reception shaft, the MTBM is removed, completing the pipeline installation.

Key Advantages of Micro-tunneling

  • Precision: Capable of achieving tight tolerances online and grade.
  • Safety: Operator safety is enhanced since there is no need for workers to be in the tunnel.
  • Environmental Impact: Reduces surface disruption and minimizes environmental impact.
  • Versatility: Effective in various ground conditions and beneath obstacles where traditional open-cut methods are not feasible.

Read more: Tunneling Methods and Encardio Rite’s Contributions to Global Projects


Encardio Rite’s Experience in Micro-tunneling

Encardio Rite, with its robust monitoring solutions and vast experience in geotechnical, geodetic, and structural health monitoring, has been instrumental in several micro tunneling projects across the globe. Below are some highlighted case studies that showcase Encardio Rite’s capabilities and achievements in this domain.


Case Study 1: Strategic Tunnel Enhancement Programme (STEP), UAE

The Strategic Tunnel Enhancement Programme (STEP) in the United Arab Emirates is an ambitious micro-tunneling project designed to significantly upgrade the wastewater management infrastructure. This initiative involved building a deep gravity tunnel, one of the longest gravity-driven sewage tunnels in the world.  


The main tunnel spans over 40 kilometers with a diameter of approximately 5 to 6 meters, lying at depths ranging from 60 to 100 meters. The project was implemented using Slurry Tunnel Boring Machines (TBMs) due to the tunnel's depth, size, and the challenging geological conditions, which included a variety of rock formations. 

Encardio Rite provided instrumentation and monitoring solutions to ensure structural integrity and precision in excavation processes. This included the installation of inclinometers to monitor lateral movements, piezometers to assess groundwater levels, and strain gauges to measure the stress on the TBM and other critical structures. The project also utilized advanced vibration monitoring systems to ensure that the tunneling did not adversely affect the surrounding structures. 

One of the significant challenges was managing the groundwater inflow due to the high-pressure conditions at great depths. The piezometric data was crucial in adjusting the TBM operations to maintain safe and effective tunneling conditions. Also, the vibration sensors played a key role in monitoring the impact of the TBM, allowing for real-time adjustments to minimize disruption. 


Case Study 2: Muharraq STP (Sewer Treatment Plant) Project, Bahrain

The Muharraq Sewage Treatment Plant Project in Bahrain entailed development of a sewage treatment facility along with a conveyance system that includes deep gravity sewers and a network of micro tunnels. This project is aimed at enhancing the capacity and efficiency of wastewater treatment in the region. 


The project includes several kilometers of micro-tunnels, with diameters typically around 1 to 1.2 meters, constructed to facilitate the efficient transfer of wastewater to the new treatment plant. These tunnels were constructed using Earth Pressure Balance Machines (EPBMs) to handle the alluvial soil conditions prevalent in the area. 

Encardio Rite used optical prism targets for precise alignment and deformation monitoring during the EPBM operations. We supplied crack meters for existing structures along the tunnel path to monitor and mitigate any potential damage from tunneling activities. 

The primary challenge in the Muharraq project was tunneling through densely populated urban areas. With our instrumentation's help, all ground movement was recorded and addressed promptly, preventing infrastructure damage and maintaining public safety throughout the project. 


Case Study 3: Inner Doha Re-Sewerage Implementation Strategy (IDRIS), Qatar

The Inner Doha Re-sewerage Implementation Strategy (IDRIS) is a major initiative by the Qatar Public Works Authority to upgrade the sanitation infrastructure in southern Doha. This project includes the development of a deep tunnel sewer network and advanced sewage treatment facilities. 


IDRIS features a main trunk sewer of 45 km with diameters between 3 and 4.5 meters, constructed at depths from 20 to 55 meters. The project employs Tunnel Boring Machines (TBMs) due to the depth and scale of the tunnels. 

Encardio Rite's role included comprehensive monitoring during the TBM drive, such as the deployment of strain gauges on the TBM thrust frame and inclinometers around the shafts to monitor subsurface lateral movements. Their geotechnical instruments played a pivotal role in real-time data acquisition, crucial for the project’s dynamic environment. 

Doha's complex subterranean landscape includes varying rock types and groundwater levels, posed significant challenges. Our monitoring tools like standpipe piezometers and seismic monitoring systems were instrumental in adapting the construction methodology to real-time geological feedback, ensuring the safety and effectiveness of the tunneling work.


Read more: Cut-and-Cover Tunneling: Methodology and Case Studies from Encardio Rite’s Global Projects


Micro-tunneling, with its numerous advantages, continues to be a preferred method for underground construction, particularly in sensitive or densely populated areas. Encardio Rite’s global footprint in micro tunneling projects underscores its expertise and the trust that industry leaders place in its technologies and services. By utilizing state-of-the-art equipment and expert knowledge, Encardio Rite contributes significantly to the safety, efficiency, and success of tunneling projects around the world.

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