The guiding accuracy of the guided mud-water balance pipe jacking machine is the core element to ensure that underground pipelines are laid accurately according to the designed trajectory. Its influencing factors run through multiple levels such as the performance of the equipment itself, the construction process, and the external environmental conditions. These factors are intertwined, and a slight deviation may cause the pipeline to deviate from the predetermined route. Therefore, it is necessary to analyze its mechanism of action from a systematic perspective.
The hardware configuration and performance of the guided mud-water balance pipe jacking machine are the basic conditions that affect the guiding accuracy. The guiding system is the "eye" of the pipe jacking machine, and the accuracy of its core sensor directly determines the accuracy of the measurement. For example, the gyroscope and inclinometer are used to monitor the posture of the pipe jacking machine in real time. If the sensor itself has zero drift or insufficient resolution, it will cause deviations in the measurement data, and then cause the guiding system to issue erroneous instructions. In addition, the hardware performance of the pipe jacking machine's cutterhead drive system and the synchronization of the jacking cylinder are also crucial. Insufficient stability of the cutterhead rotation may cause the pipe jacking machine to vibrate and interfere with the sensor signal; uneven thrust of the jacking cylinder will cause the pipe jacking machine to deviate laterally. Even if the guiding system detects the deviation, the defects in hardware performance will limit the timeliness and accuracy of the correction.
The software algorithm and control strategy of the guidance system play a key role in improving accuracy. Advanced guidance systems rely on complex mathematical models and control algorithms to convert the data collected by sensors into correction instructions. If the algorithm design is unreasonable, it may not be able to respond to small posture changes in time, resulting in the accumulation and expansion of deviations. For example, the traditional PID control algorithm has a slow response speed when dealing with sudden disturbances. After introducing adaptive control or fuzzy control algorithms, the system can dynamically adjust the control parameters according to real-time working conditions to improve the sensitivity and accuracy of correction. At the same time, the software system's data processing and filtering capabilities will also affect the guidance accuracy. If the environmental noise or abnormal data cannot be effectively filtered, it will mislead the correction decision and eventually cause the pipeline to deviate from the design trajectory.
The standardization of the construction process and the operation level are important guarantees for guidance accuracy. If the starting positioning link of the pipe jacking machine is not strictly calibrated, there will be deviations at the starting point of the pipeline laying, and the difficulty of subsequent correction will be greatly increased. In addition, the operating parameters such as mud pressure control and cutterhead speed adjustment during the jacking process are closely related to the guidance accuracy. Too high or too low mud pressure will change the stress state of the soil around the pipe jacking machine, causing the pipe jacking machine to float or sink; too fast a cutter head speed may cause the pipe jacking machine to rotate and deviate. The operator's experience and technical level are also critical. Lack of judgment on equipment characteristics and formation changes may lead to failure to take timely measures when slight deviations occur, or improper correction operations may cause greater deviations.
The complexity of formation conditions poses a direct challenge to guidance accuracy. The mechanical properties of different geological structures vary significantly. For example, the bearing capacity of soft soil formations is weak, and the pipe jacking machine is prone to settlement or lateral displacement; while the unevenness of hard rock formations may cause uneven force on the cutter head, causing the pipe jacking machine to deviate to one side. In addition, the flow state of groundwater will also affect the stability of the pipe jacking machine. Hydraulic scouring in water-rich formations may change the stress distribution of the soil around the pipe jacking machine, causing it to deviate from the designed trajectory. Abnormal geological bodies such as boulders and cavities in the strata are even more difficult to guide and control. When the pipe jacking machine encounters such obstacles, the cutting force of the cutterhead changes suddenly, which can easily cause the attitude to lose control. Even if the guidance system detects the deviation in time, the complex formation conditions will increase the difficulty and risk of deviation correction.
The maintenance and calibration of the guided mud-water balance pipe jacking machine are related to the long-term stability of the guidance accuracy. After a long period of construction, the sensor may experience performance degradation due to vibration, mud erosion and other reasons. If it is not calibrated regularly, the measurement error will gradually accumulate. For example, if the launch device of the laser guidance system is offset, the target point positioning will be inaccurate; and the wear of the hydraulic system seal inside the pipe jacking machine may cause inconsistent thrust of the jacking cylinder, affecting the attitude control. In addition, the wear of key components of the equipment will also reduce the guidance accuracy. For example, if the gap of the articulated device of the pipe jacking machine is too large, the deviation correction action will lag and the slight deviation of the pipeline cannot be effectively controlled.
External interference factors in the construction environment cannot be ignored. The densely distributed pipelines, building pile foundations and other facilities in the urban underground space will cause electromagnetic interference or physical obstruction to the guidance system of the pipe jacking machine. For example, the electromagnetic field generated by high-voltage cables may interfere with the transmission of sensor signals, resulting in data distortion; and when crossing existing pipelines at close range, the soil compression of the pipe jacking machine is uneven, which is easy to cause posture changes. In addition, the vibration of heavy vehicles on the ground and the disturbance caused by surrounding construction activities will also be transmitted to the pipe jacking machine through the soil, affecting its stability and increasing the difficulty of guidance control.
The rationality of the engineering design scheme affects the guidance accuracy from the source. If the parameters such as the curvature radius and burial depth of the pipeline design trajectory do not match the equipment performance, the construction difficulty will be increased. For example, a too small curve radius exceeds the correction capability of the pipe jacking machine. Even if the guidance system can monitor the deviation, it cannot achieve accurate correction; and an unreasonable burial depth design may place the pipe jacking machine in an unstable stratum, increasing the risk of deviation. In addition, insufficient investigation of geological conditions in the design stage and failure to accurately predict potential complex strata will also affect the guidance accuracy due to insufficient response measures during construction.
The guiding accuracy of the guided mud-water balance pipe jacking machine is the result of the coupling of multiple factors. From the hardware performance and software algorithm of the equipment, to the construction process and personnel operation, to the formation conditions and external environment, each link requires refined management and coordinated optimization. Only by fully controlling these key factors can we ensure the high accuracy and reliability of pipeline laying in pipe jacking construction and realize the efficient and safe construction of underground space projects.
