Research And Development Of The Completed Trenchless Pipeline's Three-dimensional Trajectory Detection System

Trenchless technology in China developed rapidly in recent years, it's widely used in pipeline constructions such as power line,communication line,gas line,water supply pipe and oil line because of its advantages of high efficiency, low pollution, little impact on traffic and low damage on formation etc. It is gradually replacing the traditional trench construction method of underground pipelines.In the actual project, due to the factors of construction conditions and skills, the completed trenchless pipeline's trajectory is often different with the design path of the pipeline's pilot hole. However, it's very important to accurately grasp the exact position of completed underground pipes because of two reasons:first, the exact position of completed underground pipes is the basis for final acceptance, from which we can determine the quality of the projects; second, the exact position of completed underground pipes provide the basis for the new underground pipes' path design, it can avoid the lines intersect. For the above reasons, we must test the completed underground pipes' trajectory, and it's very important to study the measuring techniques of the completed trenchless underground pipe.This paper summarized four commonly used calculation models of completed trenchless pipe's trajectory, and concluded that the minimum curvature method has the highest accuracy when it's used in the curved sections through the experimental analysis, but the minimum curvature method is not suitable for straight line sections, so this article proposed the combination trenchless pipe trajectory calculation model which was combined with the minimum curvature method and the full-width and full-distance method. This paper also summarized advantages and disadvantages of various measuring techniques of the completed trenchless underground pipe, and developed a completed trenchless pipe's trajectory measuring system which was based on the electronic compass, however, this system was very vulnerable to be affected by other magnetic field, so This paper proposed another measuring system which was based on an electronic compass and a fiber optic gyroscope,and established the theory based on the new measuring system.This article completed the new measuring system's development through the mechanical design, sensor selection, communication transmission design and the soft ware design. The soft was developed with LabVIEW based on Virtual Instruments (â…¥), it has the following features: real-time data acquisition, real-time display and the flow-up detailed data processing. The measuring system was composed by the traction rope, the tube probe, the meter, the data cable, the cable interface box, the software and the computer. When the measuring system is at work, the tube probe will be pulling by the traction rope then the tube probe will walk uniform in the pipe, the meter is fixed in the nozzle of pipe, the dada cable following the tube probes will drive the rotary encoder. At the same time the PC will make the posture sensor (electronic compass and FOG) in tube probe and the meter test the pitch angle, roll angle, the Z axis angular velocity of the tube probes vector's relative coordinate system and rotary encoder's. The data will be sent to the computer by the data cable, the computer will process the data, and get the attitude angle and the adjacent test points'distance, and then we can get the tube probe's walking path, which also is the pipe's trajectory.The measuring system has many features such as high accuracy, low cost, stable hardware and, friendly software and easy operation. The measuring system was test in the simulation pipe and the actual pipe in the field to get the system's accuracy and usefulness, in the simulation test, the trajectory data measured by the system was compared with the Total Station's measuring data and then obtained he maximum error in each axis. The paper argued that the error in the measuring system was composed by the mechanical structure error, the sensor error and the calculation model error.It's very important to study the measuring techniques of the completed trenchless underground pipe. It's the very important way to get the location data of the underground pipeline, form the database of the underground pipeline, and also is the very important way to evaluate the pipe project's quality. The trenchless pipeline trajectory measuring system R&D by this paper will have higher accuracy and practicality through further improvement, and it will have good market prospects.