Trench boxes are generally the first choice for the rapid shoring of trench runs up to a maximum of four meters wide by six meters deep in non-urban environments where ground conditions are reasonable. Generally, folks stack trench boxes in multiples to continuously support a length of the trench. Manhole box is used for rapid construction of manhole chambers and interceptors. They can be used for shoring single chambers or in conjunction with trench boxes. Boxes are available in a wide variety of sizes and weights. They comprise a base box typically around 2.5 meters high and up to 2 top extension boxes for deeper excavations. A 360-degree excavator is required to handle all boxes except backhoe types particularly as large pulling forces can be required to extract boxes in the cohesive ground.
Stack Trench Boxes | Always Read User’s Guide
The units of trench boxes are usually delivered to site broken down in component form, it is essential for the supervisor to familiar with the equipment by first thoroughly reading the user guide supplied with the higher documentation.
- The first stage in the assembly is to identify all components paying particular attention to the lifting and handling points on the box panels. Lifting points are denoted by red paint(typically), handling points which are only used for assembling the trench boxes are generally yellow. The panels most only are lifted at these designated points.
The following sequence shows how to stack trench boxes:
- Stack trench boxes commence by placing the first panel on a telescopic spreader to the required length by slipping the inner pipe within the outer pipe and securing them using a pin and r-clip.
- Lower the struts into the panel pockets and secure using pins and r-clips.
- Lower the second panel onto the struts using a foreleg chain, carefully align the panel pockets with the screw’s end, lock into position with pins and r-clips.
- Once you have secured the four leg chain, lift the assembled box into a vertical position by using the foreleg chain. Stacking of trench boxes normally commences by excavating to a maximum one meter below ground level.
- Lower the boxes into the excavation using the foreleg chain. Carefully dig and push each panel down using the excavator bucket. Advance the box downwards in no more than 300m increments excavating ahead of the panel cutting edges as required.
Easy Assembly Required
- Take care to avoid damage to the panel once the base unit is of sufficient depth, the top unit can be added to connect the units together using the four connection points. Pins are inserted from the outside and r-clips are fitted from the inside. Always ensure a safe secure means of access is provided prior to entry normal via a suitably buttered slope.
- Dig and push the assembled box to the required depth. On reaching the final depth, secure the box by back-filling against the panels and if required utter back the open ends of the excavation and save panels or trend sheets can be used to secure the ends.