MPP power pipe trenchless pipe drawing construction scheme: pipeline avoidance and jacking

MPP power pipe trenchless tubing construction is widely used in urban power pipeline laying due to its advantages of low surface interference and high construction efficiency. Among them, pipeline avoidance and jacking construction are the core links to ensure the safety and quality of the project, and it is necessary to realize the safe crossing of underground pipelines through scientific planning and precise operation.

Pipeline avoidance: pre-survey and path optimization

Pipeline avoidance The premise is to fully grasp the underground environment. Before construction, the joint survey unit needs to adopt the combination technology of "geophysical exploration + drilling": through geological radar, pipeline detector and other equipment to locate the direction, depth and material of existing underground pipelines (such as water supply pipes, gas pipes, communication optical cables), and combine drilling to obtain accurate geological data to form a three-dimensional distribution map of underground pipelines. Path planning should follow the principle of "safety distance priority", and maintain a horizontal clear distance of not less than 1.5 times the diameter of the existing pipeline, and a vertical clear distance of not less than 0.5 meters; in case of dense pipeline areas, the "upper span" or "lower penetration" scheme can be used - when the existing pipeline is buried in a shallow depth, the upward lift trajectory (slope 15) is designed, otherwise it sinks and detours to ensure that the clear distance at the intersection is up to standard. For important pipelines that cannot be avoided, protective casings (such as CPVC pipes) or artificial digging piles are used to isolate them to avoid construction disturbances.

Jacking Construction: Guidance Control and Dynamic Adjustment

The jacking process needs to be aimed at "precise guidance and stable advancement". In the selection of equipment, a horizontal directional drilling rig is selected according to the pipe diameter (commonly used φ 200-φ 630mm) and geological conditions (clay, sand, rock), and a guiding instrument (precision 20mm/30m) is used to monitor the drill bit trajectory in real time. Before construction, a guiding reference line needs to be laid on the ground, the design trajectory parameters (slope, radius of curvature) are input, and the position data is transmitted to the console through the probe built into the guiding drill bit. When the deviation exceeds 50mm, the drilling angle is adjusted in time.

Mud wall protection is a key auxiliary measure for jacking construction. For sandy and pebble formations, bentonite mud (viscosity 30-50s) is used to form a wall protection film to reduce the risk of hole wall collapse; clay formations can appropriately reduce mud viscosity and reduce resistance. During the jacking process, the drag force (80% of the pipe yield strength) needs to be controlled, and the graded jacking mode is adopted: the initial stage (first 50m) is low-speed propulsion (1-2m/min), and the speed is gradually increased after the trajectory is stable to avoid cracking of the pipe due to uneven force.

Dynamic Monitoring and Emergency Support

In order to cope with the uncertainty in the construction, a dual monitoring system of "ground + underground" needs to be established: the ground is equipped with settlement observation points (spacing 5-10m) to monitor the surface settlement (warning value 30mm); the underground is equipped with distributed optical fiber sensors to monitor the displacement and stress changes of existing pipelines in real time. If it is found that the pipeline deviation exceeds 10mm or the settlement is too fast, immediately start the emergency plan: stop jacking, adjust the mud ratio, and use grouting reinforcement (cement-water glass double liquid slurry) to stabilize the formation if necessary.

In addition, the whole construction process needs to do a good job of safety protection: set up warning areas to isolate the construction site, equip underground pipeline emergency repair equipment (such as pluggers, spare pipes), and establish a linkage mechanism with pipeline ownership units to ensure rapid response to emergencies. Through the above measures, the safe avoidance and precise jacking of pipelines in the construction of trenchless tubing of MPP power pipes can be effectively realized, providing reliable technical support for urban power infrastructure buildings.