Slurry Type Pipe Jacking:
where it all started for us
In modern cities and other living areas, there are lifelines such as sewerage, water, gas, electricity, and telecommunications, many of which are buried underground as culverts. There are three methods for burying these culverts.
① Open Cut Method excavates from the ground, lays pipes to the bottom of the hole, and backfill the ground.
② Shield Method assembles segments behind a shield machine as it excavates the ground to form a pipeline.
③ Pipe Jacking Method thrusts a MTBM through jacking pipes and jacking pipes are installed into the ground to form a pipeline.
In the pipe jacking method, shafts are set up at both ends of the planned line, and a hydraulic jack is used to press a MTBM through jacking pipes into the ground from a shaft equipped with thrust jacking equipment.
As for the history of the pipe jacking method, it is documented that the method was implemented at the end of the 19th century in the United States.
In the early days, pipe jacking was a special method for laying gas, water, and communication cables across tracks, waterways, and roads. It gradually became to be used for laying pipes in the direction of road crossings and was also widely used in sewerage projects.
The slurry type pipe jacking method was developed then with the technology of the shield tunneling method to improve safety. In addition, a wide variety of small-diameter pipe jacking methods have been developed to meet the demands of society.
The slurry type pipe jacking method has improved for longer jacking distances, sharp curves, etc. In addition, the development and automation of microtunneling equipment have been made to ensure the reliable construction of these projects, contributing greatly to the maintenance of sewers and other lifelines.
Main Methods of Laying Pipelines
The method of laying pipelines underground is classified into the following:
① Open-Cut Method:
- excavates a trench from the road to the depth where the pipeline is to be laid.
- lays the pipe, and backfills the upper part of the trench with high-quality soil or improved soil to restore the road.
② Trenchless Method:
- a MTBM is inserted from a shaft.
- the ground is excavated only in the area where the pipeline is to be laid.
- the pipe is pressed into the ground while removing the excavated soil to construct the pipeline.
Two Types of Trenchless Methods
There are two types of trenchless methods:
① Shield tunneling method: the segment is formed as the tunneling machine (shield machine) excavates the ground.
② Pipe jacking method: thrusts a MTBM from the shaft through jacking pipes to excavate the ground and the jacking pipes are laid to form a pipeline.
Advantages of the Pipe Jacking Method:
① Less influence on the traffic as the excavation area is limited.
② Less amount of excavated soil and waste soil due to the limited excavation area.
③ Economical benefit over open-cut method when earth cover is deep.
④ Better option than the open-cut method in an urban area, etc.
⑤ It is possible to install pipelines crossing a road or river.
Classification of Pipe Jacking Method:
① Large-and Medium-Diameter Pipe Jacking Method: for pipe ID 800mm to 3000mm
② Small-Diameter Pipe Jacking Method: for pipe ID 700mm or smaller.
③ Super Large-Diameter Pipe Jacking Method: for pipe ID 3000mm or larger.
Outline of the Unclemole Method
In the Unclemole method, the cutter chamber is filled with slurry, and the pressure of the mud counteracts the earth pressure and groundwater level acting on the cutterface to prevent the collapse of the ground. The jacking pipe is pressed into the ground by the thrust jack installed in the drive shaft while excavating with the cutter head to construct the pipeline.
The excavated soil is mixed with slurry and transported as drainage water, and the drainage water is separated into sediment and slurry by a slurry treatment plant outside the shaft.
Unclemole Pipe Jacking System
As shown in the figure below, the Unclemole method consists of shafts, counterpressure walls, thrust jacks, thrust rings, struts, jacking pipes, and Unclemole MTBM.
Unlemole is applicable to the following types of pipes:
Applicable pipe diameter (ID): 200mm to 3500mm
- concrete pipes
- ductile iron pipes
- steel pipes
- polyvinyl chloride pipes
Applicable Soil Types
Applicable soil types for the Unclemole method are as follows:
① Cohesive soil (volcanic ashy clay, organic soil, clayey soil, silt)
② Sandy soil (sandy soil, sand)
③ Gravelly soil (gravelly soil, gravel)
④ Coarse stones (coarse stone-mixed sand, coarse stone-mixed gravel)
⑤ Boulders (boulder-studded sand, boulder-studded gravel)
⑥ Bedrock (soft rock, medium-soft rock, hard rock)
Advantages of Unclemole Method
① Excavation and soil removal are simultaneously processed in the circulation of slurry. Safety is ensured as no one needs to go inside jacking pipes.
② The eccentric crushing mechanism is applicable to a wide range of soil types.
③ High accuracy is easily ensured with Reflective Steering Guidance (RSG).
④ Compatible with a wide range of pipe types
⑤ Stability of the cutterface is ensured even in the ground with high water pressure or drastic changes in groundwater pressure.
⑥ Suitable for long-distance pipe jacking as it can transport slurry over long distances.
⑦ Less amount of industrial waste is generated as excavated soil is separated into soil and slurry by the primary processor and the separated soil is reused as general residual soil and the slurry as circulating slurry.
⑧ Even longer distance pipe jacking is possible with a lubricant mix soil system (LMS).
⑨ Curve construction is possible.
⑩ The construction period can be shortened as the excavation speed is fast, making it economical.
※RSG（Reflective Steering Guidance）
RSG (Reflective Steering Guidance) is a system that indicates the deviation between the posture position of the head of Unclemole and the jacking planning line by projecting the laser reflected from the mirror at the front of Unclemole onto the directional control screen. In the case shown in the figure, the posture position of Unclemole is downward, so it is necessary to turn the head of Unclemole upward. By aligning the laser spot with the center of the directional control screen, it is easy for an operator who is new to Unclemole to ensure high accuracy.
Unclemole for Different Pipe Types
① Concrete Pipes, Ductile Iron Pipes, Reinforced Plastic Composite Pipes, etc.
The following machines are for you when jacking concrete pipes, ductile iron pipes, reinforced plastic composite pipes, etc.:
② Polyvinyl Chloride (PVC) Pipes
Unclemole V (TCV) is an ideal machine when jacking rigid polyvinyl chloride (PVC) pipes with low axial strength.
③ Steel Pipes
Steel pipes are used as casing pipes to lay the main pipe. It is also used for the piperoofing method, to construct a protective roof or wall to minimize settlement of the ground during excavation, and to construct underground spaces.
Shuttlemole is a method where a MTBM is retracted through jacked pipes and retrieved from a drive shaft. You do not need an arrival shaft with this method.
Contact us to see which machine is suited best for your project.
A Half-Century of Experience and Still Counting
In 50 years since its development, more than 2,500 units of Unclemole MTBMs have been sold, contributing to the construction of various infrastructures around the world.
We have evolved our technology to meet the needs of users with our machines that are capable of pipe jacking with long-distance, curves, and various soil types while ensuring stable excavation speed and accuracy through years of experience and technological development. We have contributed to the development of the world with our accurate, fast, and safe technology. In the future, this technology will be used for next-generation communication networks to be installed underground in developed countries, replacement of aging sewer pipes, and construction of initial infrastructure such as sewerage systems in emerging countries.
We will continue to evolve day by day so that we can safely and quickly make valuable contributions to the development of the world.
Contact us for any questions or requests.