GEO and Soletanche Polska started the planning and logistics phase prior to the site deployment. During this time of planning the slurry Batching Plant volumes and sketch were presented and approved to be implemented on site.
PolyMud® slurry was used as an alternative to bentonite. All the diaphragm wall scope of work was concluded with the soil stabilization being assured by Polymud® as the base. Combined Polymer slurry and GFiber® application was made on slurry supply to the trench as means of control fluid losses in the more porous soil layers.
Challenges
Client had no experience using polymer fluids and wished to develop its usual work without worries: creating an adequate batching plant and efficient production cycles. The short deadline to deliver the job also led to a demanding production target. All of this, while attaining an optimum soil stabilization to achieve very smooth walls, for future exposure.
The d-wall panels were not very deep but the soil profile included porous soil layers, with potential for fluid loss. These losses could make difficult the slurry level maintenance and lead to collapse. It would also increase polymer consumption.
Solution
PolyMud® slurry was used as an alternative to bentonite. All the diaphragm wall scope of work was concluded with the soil stabilization being assured with Polymer slurry combined with GFiber® supplied to the trench as means of fluid loss control in the more porous soil layers.
Effective soil stabilization was achieved at all times. No substantial drop on slurry level occurred as the use of GFiber maintained the losses to a minimum. This, combined with the zero time needed to preform panel desanding/cleaning, potentiated the swiftness in the operations and led to a real increase in production – the average production was of 140m2/day without auxiliary crane.
All the operations were closely supervised by GEO’s Engineer deployed to site, developing a hassle-free operation, assisting client in every stage of the process.
Key Figures
Scope:
16 panels (12 of 500mm and 4 of 600mm width) with average depth of 10 meters were completed. The total scope of D-wall was close to 1300m2.
Achievements:
Median concrete overbreak of 6.7%.
Average production of 140m2/day with only one cable grab rig. Excavation progress rate and panel completion timing as per the expectations.
Geology:
The site soil profile starts with a shallow first layer of backfilled material (made soil), from 0 to 1.5m; then a fine slightly clayey/silty Sand, from 1.5 to 3.0m; followed by a stiff clayey Sand, from 3 to 15m, where the base of the panel was set.
