The Project
Groundforce Shorco have provided a unique ground support solution to Barhale Construction for a flood alleviation scheme in Gloucester. The Midland Road scheme forms part of Severn Trent’s
AMP4 sewerage infrastructure programme and involves installing approximately 200m of twin 2.8m diameter, high density polyethylene pipes in an 8m wide x 6.5m deep trench. The pipeline forms temporary underground storage for storm water run-off. During storms water passes into the storage tank via a series of manifold chambers before being channelled back into the existing sewer network as the storm flows subside.
The Problem
Ground conditions in the Midland road area are relatively poor and quite variable due to differing depths of made ground. Below 2.5m stiff clay and mudstone would make installing sheet piles very difficult.
High clearance between and under any cross strutting was a key requirement for the excavation support. The trench, approximately 8m in width, ran to up to 6.5m deep in places.
This project was undertaken in an environmentally sensitive area bordering both a residential area and busy main road.
The Equipment
The Rolling Strut Slide Rail system is exclusively available from Groundforce Shorco. The system offers a unique ground support solution in deep and wide trenches and in difficult ground conditions, allowing much simpler installation techniques and greater accessibility for installing pipework.
The Rolling Strut Slide Rail, unlike traditional slide rail systems, incorporates moveable struts than can be pushed down/ pulled up by an excavator bucket in order to create large clear access areas for installing large pipes. This unique design of strut enables much wider and deeper excavations to be safely supported as opposed to what can be accommodated by conventional trench boxes.
The Solution
In looking for suitable equipment to use for the temporary works on this project, Barhale Construction considered the use of interlocking sheet piles and support frames. This option would have involved the use of heavy piling equipment, causing greater levels of noise and vibration. Due to these factors and the greater potential cost involved, this was rejected.
The Rolling Strut Slide Rail system provided the optimum solution due to the large size of the excavation, ground conditions and quieter methods of installation. The system was installed using a 36 tonne excavator.
This equipment was the ideal solution for the project as it also caters for underground services crossing the trench, via a specially adapted piling panel.
Technical Support
In conjunction with specialist German manufacturer SBH and main contractor Barhale Construction, Groundforce Shorco’s Technical Department produced detailed design calculations and drawings showing the construction sequence.
Due to the loadings produced by size and depth of excavation, poor ground conditions and the need to provide a large under strut clearance a huge single 1.2m deep “mega” strut was used in conjunction with 7.5m long support posts
Our Technical Team liaised with all parties concerned in order to achieve a safe and cost effective solution. Through use of the Rolling Strut Slide Rail System the main contractor was able to reduce the project length by six weeks.