Geotechnical - Page 2
Soils modification and stabilisation — The potential for the conversion of very low strength soils to engineering fill by the controlled blending of lime / cement / pfa or granular wastes is often the key to the economic success of brownfield developments. Laboratory trials at feasibility stage are; however, only the first step as the materials are rarely consistent in nature and yet must be converted to a controlled fill material with predictable long term geotechnical characteristics.
Soils are modified in situ using Wirtgen rotavators and ex situ using a batch process pugmill.
Band drains — Vertical plastic micro core drains which are inserted into the soft laminated soils such as peat or clays to provide a pathway for the rapid dispersion of pore-water pressure resulting from an imposed surcharge. This results in an accelerated consolidation of compressible soils. The rigs available have a maximum penetration of 22m and outputs of up to 800 lin.m per hour.
Plastic Piling — Employed as either a river bank protection system or a deep cut-off system for groundwater or leachate. Using a specially designed steel sleeve, the piles are driven to depths of up to 6m through most ground conditions.
Reinforced Earth — Using a combination of granular soils, geogrids, geotextiles and weldmesh, walls can be constructed with long-term stability guarantees for slopes between 45 and 90 degrees. The appearance of the wall can be enhanced by a variety of finishes including retained vegetation, criblock concrete panels or traditional dry stone walling.
Landfill Systems — The construction of landfill cells and leachate treatment systems employs the foundation clay mineral liners followed by the extensive use of geotextiles, geofabrics and polyethylene liners. Blackwell has extensive experience in the controlled deposition and compaction of the mineral liners to achieve the strict permeability criterion. The subsequent LD, MD or HDPE liners are then placed by specialist subcontractors under Blackwell’s CQA regime.
Embankment Reconstruction — The repair of shallow or deep seated embankment failures invariably require completion with little allowable disruption to the adjacent track or road and therefore provide limited access for any traditional disposal or import operation. Various technologies are employed to convert the failed material into reusable engineering fill. This includes lime and or cement modification of the basic soils with reinforcement of the mass provided by geogrids, soil nailing and lime piling.
|
