How is alignment, camber and elevation controlled in a remote-controlled pipe jacking?

Q: How is alignment, camber and elevation controlled in a remote-controlled pipe jacking?

The geometric control of the microtunnel is carried out by means of laser or gyroscopic navigation systems that allow real-time monitoring of the position of the TBM with respect to the theoretical axis. The alignment is corrected by means of shield orientation cylinders, while the curvature is maintained respecting the minimum admissible radius for the tube-joint assembly. The elevation or slope is controlled by inclination sensors and the laser impact point on the target, adjusting the thrust, the chamber pressure and the cutting torque. All parameters are recorded in a final as-built that certifies tolerances and QA/QC.

The control of the alignmentthe curvature and the coordinate is one of the critical elements in pipe ramming by means of microtunnel, It determines the final accuracy of the layout, hydraulic functionality and compliance with geometric tolerances. The remote-controlled tunnel boring machine (MTBM) incorporates advanced navigation systems that allow its position to be monitored in real time and any deviations to be corrected during progress.

1. Alignment control (plant)

The tunnel boring machine is guided by a system of laser navigation o gyroscope which compares the actual position with the theoretical tunnel axis. Based on this reading, the operator corrects the trajectory using lateral cylinders installed on the shield. This ensures that the feed follows the intended direction, even in heterogeneous terrain or in the presence of interferences.

For projects with demanding layouts, see the example of the microtunnel with complex alignment in El Arenao, where continuous millimeter corrections were used to maintain the intended geometry.

2. Curvature control

Bending radii are limited by the tube-joint system, the type of lubrication and the capabilities of the pushing equipment. In curved microtunnels, a minimum allowable radius which avoids overstressing of joints and pusher stations. The MTBM adjusts the orientation progressively to describe the curve safely while maintaining an even load distribution.

3. Dimension control (elevation or slope)

The slope is controlled by the guidance system itself, inclination sensors and the reading of the laser impact point on the target. This control is essential in gravity sewers, where minor variations can significantly affect hydraulic performance.

The operator adjusts chamber pressure, cutting torque and thrust to maintain elevation, avoiding local collapse or shield bounce due to sudden changes in terrain.

4. Continuous and as-built monitoring

During driving, deviations in plan, elevation, thrust per ring, pressures and advance parameters are recorded. All this information is integrated into a as-built The final certificate certifies the tolerances achieved and is delivered to the customer as part of the QA/QC checks.

An introduction to the complete method can be found in the publication what is pipe jacking and how is it applied in subway projects?.