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Expert Answers to Ten Questions on Trenchless Technology: Do You Know Them All?
Expert Answers to Ten Questions on Trenchless Technology: Do You Know Them All?
Expert Answers to Ten Questions on Trenchless Technology: Do You Know Them All?
2025-09-18
1. What is Trenchless Technology? Why is it Needed?
Answer:
(1) It refers to the pipeline laying, replacement, and repair work carried out without excavation, passing through rivers, lakes, important transportation trunk lines, and important buildings.
(2) Social reasons: It can solve the interference of traditional excavation construction on residents' normal life, as well as the damage and adverse effects on traffic, the environment, and the foundations of surrounding buildings.
(3) Economic reasons: It has good economic and social benefits. Under the same comparable conditions, the cost of trenchless pipeline laying, replacement, and repair is lower than that of excavation construction. The larger the pipe diameter and the greater the burial depth, the more obvious this cost advantage becomes.
(4) Technical reasons: In situations where traditional construction methods cannot be applied or excavation construction is not allowed, trenchless technology can be used to lay pipelines by crossing underneath, and the pipelines can be designed to pass through the optimal location with the minimum engineering volume. It can control the laying direction and burial depth of underground pipelines with high precision and bypass undiscovered underground obstacles. Drain all the oil-water mixture from the oil pan. Rinse with clean water until no dirt flows out, then use kerosene or light diesel to rinse the oil pan. Add a sufficient amount of cleaning oil (diesel) until it fills up to the oil filler port (or until the cleaning oil overflows, as some machines have their exhaust pipes in the middle of the engine). Insert compressed air as far as possible into the lower part of the cleaning oil for boiling-type flushing, which can mix the silt deposited on components with the cleaning oil. Stop and drain the oil when the valve rocker assembly is visually clean (checked through the oil filler port).all the oil-water mixture from the oil pan. Rinse with clean water until no dirt flows out, then use kerosene or light diesel to rinse the oil pan. Add a sufficient amount of cleaning oil (diesel) until it fills up to the oil filler port (or until the cleaning oil overflows, as some machines have their exhaust pipes in the middle of the engine). Insert compressed air as far as possible into the lower part of the cleaning oil for boiling-type flushing, which can mix the silt deposited on components with the cleaning oil. Stop and drain the oil when the valve rocker assembly is visually clean (checked through the oil filler port). 
2. What Technologies are Included in Trenchless Technology?
Answer:
(1) Engineering geological condition investigation technology
(2) Underground pipeline detection technology
(3) Pipeline internal inspection technology
(4) Horizontal directional drilling technology
(5) Pipe jacking/micro-tunneling technology
(6) Impact mole and pipe ramming construction technology
(7) In-situ pipeline repair and replacement technology2. Use the starter to drive the hydraulic pump to idle until the hydraulic oil discharged by the pump contains no bubbles.
3. What are the Pipe Materials for Underground Pipelines? What are the Main Pipe Materials for Drainage Pipes, Gas Pipes, and Thermal Pipes?
Answer: The main pipe materials include steel pipes, cast iron pipes, plastic pipes, reinforced concrete pipes, and concrete pipes.
（1）Drainage pipes: Precast concrete pipes, reinforced concrete pipes, cast iron pipes, asbestos-cement pipes, clay pipes, and ceramic pipes.
（2）Gas pipes: Mostly steel pipes, followed by spigot-and-socket cast iron pipes and polyvinyl chloride (PVC) plastic pipes.
（2）Gas pipes: Mostly steel pipes, followed by spigot-and-socket cast iron pipes and polyvinyl chloride (PVC) plastic pipes.
（3）Thermal pipes: Seamless steel pipes and steel plate coiled-welded pipes. Plastic pipes and cast iron pipes are also used secondarily.Clean the rotary reducer with cleaning oil, and add lubricating oil after it passes inspection.
4. Are You Familiar with the Following Pipe Materials: PE, PP, PVC, GRP, HDPE?
Answer:
• PE: Polyethylene
• PP: Polypropylene
• PVC: Polyvinyl Chloride
• GRP: Glass Fiber Reinforced Plastic Resin
5. Is Trenchless Technology Universal? When is Excavation Feasible?
Answer: Trenchless construction is suitable when its cost is lower than that of excavation construction, which occurs in the following situations:
(1) Burial depth greater than 3 meters;
(2) Under busy roads;
(3) Near existing underground pipelines;
(4) In unstable strata;
(5) Below the groundwater level;
(6) In environmentally sensitive areas;
(7) In industrial, commercial areas, or residential areas.
6. Briefly Describe the Principle of Guided Drilling?
Answer:
(1) Guided drilling is completed through the cooperation of a guide bit, a drilling rig, and a guiding instrument.
(2) If the drill string is fed and rotated simultaneously, the inclined surface loses directionality, enabling straight drilling.
(3) If the drill string is only fed without rotation, the reaction force acting on the inclined surface changes the direction of the drill bit, realizing directional drilling (deflection drilling).
7. What Environmental Problems Can Horizontal Directional Drilling Be Used to Address?
Answer:
Groundwater extraction, soil gasification separation, recovery of free products, biological remediation, soil washing and chemical stabilization, as well as soil monitoring and sampling.
8. Common Technical Difficulties and Countermeasures in Horizontal Directional Drilling? (Hole Collapse, Drilling Fluid Loss, Pipe Sticking)
Answer:
a. Hole Collapse: It refers to the phenomenon where rocks or soil blocks on the hole wall fall into the hole to varying degrees due to certain reasons.
Prevention measures:
1. Adjust and maintain appropriate drilling fluid density and rheological properties;
2. Avoid excessive speed when starting the pump and tripping the drill string;
3. Improve drilling speed and shorten the construction period.
b. Drilling Fluid Loss
Prevention measures:
1. Reduce pressure surges to avoid fracturing and fluid loss;
2. Use low-density drilling fluid;
3. Maintain a low drilling fluid return velocity;
4. Prepare sufficient drilling fluid.
c. Pipe Sticking: Ineffective handling of drilling fluid loss and hole collapse can lead to pipe sticking, including adhesive sticking, sand settling sticking, hole collapse sticking, mud cake sticking, and hole shrinkage sticking.
Prevention measures: Maintain good, uniform, and stable drilling fluid performance, control the solid content of the drilling fluid, and add lubricating substances or lubricants.9. How to Successfully Cross Hard Rock Formations?
Answer:
For drilling and reaming, hard rock has the following characteristics:
For drilling and reaming, hard rock has the following characteristics:
(1) Due to the hardness and high friction of rock, the energy consumption required for rock breaking during drilling is high, the drilling speed is slow, the drill bit wears seriously, and it is prone to overheating and bit burning.
(2) The wellbore formed by drilling in hard rock is relatively stable. Except for encountering large formation fracture zones, it is generally not prone to collapse like that in soil layers, mudstone shale, and gravel layers.
(3) Since hard rock drilling mostly uses grinding to break rocks, the drill cuttings are small in size, making it easier to suspend and discharge the cuttings.
The design of drilling fluid for hard rock formations should focus on enhancing lubricity and cooling performance, and reducing the solid content to improve drilling speed; while the requirements for the cutting suspension and wellbore stabilization capabilities of the drilling fluid are usually not high.
In terms of reducing pipeline laying resistance, during trenchless pipeline laying in many formations, high resistance in pipe jacking and pipe pulling is often encountered, leading to difficulties in pipeline laying and sometimes even abandonment halfway. One of the key technologies to solve this problem is to use drilling fluid with good lubricating performance, which can significantly reduce the friction coefficient of the hole wall soil and rock.
10. What are the Methods for Pipeline Internal Inspection? What Types of Damages Can Each Detect?
Answer:
International methods: TV inspection, fiber optic endoscopy, sonar inspection, dye testing, smoke testing, leak detection and plugging rings.
Domestic methods: Mud measuring bucket inspection, standard ox inspection, ground subsidence judgment, downhole light transmission inspection, sludge composition judgment, and diver inspection.
Sonar method: It uses reflected high-frequency sound waves to locate discontinuities in the medium.
1. It can inspect the parts covered by water or sludge;
2. It can provide data on pipeline dimensions (pipeline end face size and shape)
Rollins
Sales Manager
Jiangsu Goodeng Heavy Machinery Technology Co.,Ltd
Tel: +8618091738445 Whatsapp:8618091738445
Email: songhaomin@goodeng.com.cn
Website: www.goodeng.com.cn