The mud-water balance pipe jacking machine's slurry circulation system is its core functional module. Its efficient operation relies on the precise coordination of multiple aspects, including slurry proportioning, pressure control, equipment coordination, and dynamic adjustment. This system uses slurry as a medium to form a stable mud film to protect the excavation face during jacking, balancing the water and soil pressure at the excavation face, and simultaneously achieving efficient transport of excavated soil, providing crucial support for the continuous and safe tunneling of the pipe jacking machine.
Slurry proportioning is fundamental to the efficient operation of the slurry circulation system. Depending on geological conditions, the viscosity, density, and additive composition of the slurry need to be adjusted accordingly. For example, in sandy or soft soil strata, the slurry viscosity needs to be increased to enhance the excavation-carrying capacity and prevent soil sedimentation and blockage of the pipe; in hard rock strata, the slurry density needs to be reduced to minimize wear on the cutterhead. Through laboratory tests and field debugging, the optimal proportioning parameters are determined to ensure that the slurry can both form a dense mud film to stabilize the excavation face and efficiently carry away the excavated soil, avoiding system downtime or reduced tunneling efficiency due to insufficient slurry performance.
Precise control of slurry pressure is crucial for maintaining excavation face stability. The system regulates the slurry chamber pressure through the flow difference between the inlet and outlet pumps, dynamically balancing it with groundwater pressure and soil load. Excessive pressure can cause ground heave; insufficient pressure can lead to excavation face collapse. Guided mud-water balance pipe jacking machines are typically equipped with pressure sensors and automatic control systems to monitor and adjust slurry pressure in real time, ensuring it fluctuates within a safe range. For example, when traversing water-rich strata, the system increases slurry pressure to counteract groundwater seepage and prevent mud film rupture; when approaching buildings or underground pipelines, it fine-tunes pressure to control ground settlement and ensure construction safety.
Equipment coordination is key to the efficient operation of the slurry circulation system. The inlet pump delivers the prepared slurry to the slurry chamber at the front of the pipe jacking machine, while the outlet pump pumps the slurry mixed with soil and debris to the surface treatment equipment. The flow rates of the two pumps must be strictly matched; typically, the outlet pump flow rate is slightly higher than the inlet pump flow rate to maintain stable slurry chamber pressure. Meanwhile, mud treatment equipment (such as vibrating screens and hydrocyclones) must efficiently separate soil and debris from the mud to ensure the recycled mud meets performance standards. If equipment coordination is poor, such as insufficient flow from the mud discharge pump, it can lead to a sudden increase in pressure in the mud-water chamber, triggering a shutdown protection mechanism. Conversely, if the treatment equipment is inefficient, the soil and debris content in the mud will be too high, affecting the debris-carrying effect and accelerating equipment wear.
Dynamic adjustment capability is essential for handling complex geological conditions. Guided mud-water balance pipe jacking machines may traverse various strata during tunneling, requiring the mud-water circulation system to adjust parameters in real time according to geological changes. For example, when entering a sand layer from soft soil, the system needs to increase mud viscosity and reduce tunneling speed to prevent rapid sand sedimentation and pipe blockage; when entering a rock layer from a sand layer, it needs to switch to high-density mud and optimize the cutterhead speed to meet the cutting requirements of hard rock. Furthermore, the system must possess self-diagnostic and emergency handling capabilities, such as automatically initiating a reverse flushing program or adjusting the tunneling direction when a blockage is detected in the mud discharge pipe, to avoid prolonged downtime.
Slurry recycling and reuse are crucial for improving the system's economic efficiency. Clean slurry separated from surface treatment equipment can be recycled back into the slurry intake system, reducing the consumption of fresh slurry. Optimizing the slurry recycling process, such as using high-efficiency hydrocyclones to improve separation accuracy, can reduce slurry treatment costs and waste slurry emissions. Some projects also use chemical agents to improve slurry performance, extend its service life, and further reduce construction costs.
The integrated application of a guidance system provides directional assurance for the slurry circulation system. Laser guidance systems or gyroscopes monitor the pipe jacking machine's attitude in real time, feeding back positional deviation data to the correction cylinders to ensure the machine tunnels along the designed axis. If the jacking direction deviates, the system prioritizes adjusting the slurry pressure distribution, using the asymmetrical support of the slurry on the excavation face for micro-correction; if the deviation is large, the correction cylinders are activated for forced adjustment. This dual-guarantee mechanism of "slurry guidance + mechanical correction" significantly improves jacking accuracy and reduces the risk of repeated tunneling or pipeline damage due to directional deviations.
The guided mud-water balance pipe jacking machine's mud-water circulation system achieves a unified balance between excavation face stability, efficient soil and debris transport, and precise control of the jacking direction through optimized mud ratio, precise pressure control, efficient equipment coordination, dynamic parameter adjustment, mud recycling, and integrated guiding system. Its efficient operation not only improves construction efficiency and safety but also reduces the impact on the surrounding environment, providing reliable technical support for urban underground space development.
