1.Project Overview
The main pipeline of the Shangqiu Central Heating Project uses Φ1220*14mm steel pipes with a Φ1370*17mm HDPE protection sleeve.
In order to reduce the impact on road traffic during the construction process, trenchless directional drilling was used for crossing construction in some sections of the road. The geology of the crossing area is dominated by silt and silty clay. The crossing distance of this section of the project is 400 meters, and the crossing obstacles are rivers and highways.
2.Model selection
According to the pipeline specifications, stratum conditions, construction distance and other factors, the use of about 300 tons of horizontal directional drilling rigs can meet the construction requirements. The construction party selected XCMG XZ3000 horizontal directional drilling rig for construction after investigation.
3.Drilling tool configuration
| 钻杆 | 安全扭矩 | 曲率半径 | 重量 | |
| 140*9600 mm | 120 kN·m | 110 m | 425 kg | |
| 导向钻具名称 | 规格 | |||
| 斜板式导向钻头 | 140 | |||
| 扩孔器名称 | 规格 | |||
| 挤扩式扩孔器 | Φ600mm~Φ1800mm | |||
4.Construction technology
Integral suspension is adopted when the pipeline is pulled back
Guidance: within 15 meters of construction depth, wireless guidance instruments can be used. The construction stratum is dominated by silt and silty clay, which are easy to drill into holes, and use inclined plate guide bit for drilling.
Reaming: In the reaming stage, a squeeze-expanding reamer is used to ream in stages. The reaming span of each stage can be appropriately expanded to 200mm, and the final hole diameter is 1800mm.
Back drag: Use the suspension method to prevent friction between the pipeline and the ground, and enter the borehole at a reasonable angle to reduce the drag resistance.
Pipeline tow successfully
5.Case summary
The guiding construction should be carried out in strict accordance with the allowable bending radius of the pipeline to ensure that the bending state of the pipeline in the hole is close to that of the drilled hole, thereby reducing the drag resistance.
Minimize the entry and exit angle of large-diameter pipeline construction, especially the excavation angle. If the excavation angle is too large, in order to ensure that the pipeline enters the hole at a reasonable angle, the lifting height of the pipeline or the excavation depth of the guide trench will be increased.
When the pipeline is pulled back, a large amount of mud will be discharged from the hole, and mud collection work needs to be done to prevent pollution of the surrounding environment.
Prepare construction accident handling plans so that emergency rescue and rescue can be carried out quickly after the accident. The earlier the rescue is carried out, the greater the possibility of success.
