CAST-IN-PLACE REINFORCED CONCRETE “DIAPHRAGM WALL”
ABSTRACT: Diaphragm Walls are cast-in-situ walls used as retaining walls for perimeter walls of deep, multi-level basements and underground parking facilities, subways, subway stations, underpasses and shaft walls. bridge abutments, dams’ foundations, cofferdams, walls for underground water reservoirs, canal training walls, underground drainage and sewage covered canals, walls, seawalls, dry docks, pollution control. . FS diaphragm walls can also be used in rock excavation for dam foundations “T”-Shaped diaphragm walls are used for deep-water wharves.
DIAPHRAGM WALLS (DW) is a technology carried by Foundation Specialists, Inc.
Diaphragm Walls are a type of “Top-Down” Construction used to put in place, construct Impervious Permanent Retaining Walls ahead of proceeding with the general excavation of the area. DW are Ideally suited for Slope Protection of Large Deep Excavation in built-up areas, Deep Building Basements, Buildings’ Shear-Walls Foundations, Industrial Plants’ Pits, Mass Transit Subway Stations, Rolling Mills Pits, River Training Walls, City Canals Walls, Storm Drainage Walls, Wharfs, Water Pumping Stations , Sewage Treatment Plants, Sea Walls, and in any instance where a permanent reliable, indefinitely impervious retaining structure is needed. Cast in Place DW and Plastic Cut-of Walls are used also as the Impervious “core” of Earth Dams and cofferdams Diaphragm Walls , as above, are a Top-Down Construction Technology, and particularly suited for “difficult” soil formations and very deep excavations, in presence or absence of water table and both in cohesive and non-cohesive soil formations. Execution of DW is preceded by the construction of R-C Guide Walls. Excavation of DW is done in segments or single “panels” with horizontal length generally varying from 2.0 meters to 3.5 meters , depending on the parameters of the soil being excavated, Standard Thickness of the DW varies from 600 mm to 1500mm and DW depth can reach 100 meters. Foundation Specialists, Inc. [FS] also executes “T” shaped DW used for wharfs construction in deep water .
Diaphragm Walls built to retain deep excavation will be generally Anchored by Post-Tensioned Ground Anchors either temporary or permanent, or in case of building basements the support can be by temporary props to be removed once the basement permanent structure (slabs & beams) will have been built against the DW .
DW installation produces zero disturbance of the surroundings, including avoidance of water table lowering, and/or zero settlement of neighboring structures.
As stated here-above Diaphragm Walls are executed using a segmental installation technique, [generating Reinforced Concrete DW Panels of predetermined dimensions] purposely and specifically designed for each soil formation and particular site requirements, in order to avoid any disturbance and subsidence to the surrounding areas.
In cohesionless soil formations under the water-table, the segmental excavation is generally carried out using bentonite suspension as the drilling fluid, in order to balance the action of the water-table and to maintain the excavation perfectly stable until each single “ Panel ” is cast with concrete.
Once all the segments or “ Panels “ are cast, they are connected at the top by a reinforced concrete continuous beam [ Coping Beam or Top Beam ], after which, removal of soil on the excavation side can proceed, protected by the Diaphragm Wall.
The Diaphragm Wall, depending upon depth of excavation and upon design loads to be applied on the “ earth side “ can be designed to act as a cantilever or as an anchored retaining structure, in this last case, soil or rock anchors shall be drilled, installed and generally post tensioned, at one or more levels (as per design), when excavation reaches the required elevation. In order to assure the water-tightness of Diaphragm Walls, and to provide construction Keys between DW Panels. The DW construction can be made using Primary and Secondary Panels, where Primary panels are cast with Removable Form Joints. Diaphragm Wall is sometime called Slurry Wall.
Another type of Diaphragm Wall carried by Foundation Specialists is a Technology called Cut-Off Wall or Self-Hardening Plastic Cut-off Wall .
The Cut-Off Wall is a continuous and impermeable wall, generally made using a mix of Cement-Bentonite, designed to remain indefinitely, both sufficiently plastic in order to follow soil movement and deformation without cracking and totally impervious.
Cut-Off Walls are employed whenever there is a requirement for isolating a source of pollution from the surrounding water table, e.g. around Sanitary Landfills, Mine Tailing, or other sources of polluting leachates.
Diaphragm wall are also constructed by Foundation Specialists, Inc using Contiguous Piles, Secant Piles, or Tangent Piles, provided with a Top Beam, and, depending on the height and nature of the retained soil formation, and the purpose of the retaining structure, the Pile-Wall can be self-standing or anchored , impervious or pervious.
We list down here some of the Diaphragm Projects Designed and Executed by Foundation Specialists, Inc. since 1978 :
● Kalayaan Hydroelectric Pumped Storage Plant Project , Laguna, Lower Canal Training Walls; Dock wharf., Iligan City
● NSC (National Steel Corporation) Five Stands Tandem Cold Mill Perimeter DW and King Piles to support the Gantry Cranes and Plant's Roof Constructed in parallel with the Pit's excavation
● NSC Hot Strip Mill Iligan City
● NSC Two Stands Temper Mill, Iligan City
● Marginal Wharf, Iligan City
● DW for the anchoring of Marginal Wharf, Iligan City
● Eduarosa Condominium, Roxas Blvd, Paranaque City (3+1 Basement Levels)
● Bayview Towers, Roxas Blvd Paranaque City (3+1 Basement Levels)
● Asiaworld Plaza Hotel & Resort, Reclamation MM, 5 Level Basements
● Chateau De Baie, Roxas Blvs Pasay City 3+1 Basement Levels
● Stanford Bldg Roxas Blvd 3+1 Basement Levels
● China Steel Towers, Binondo, Manila one entire City Block Multi-Storey Basement
● Perla Mansion Palanca St Makati City, 7 Underground Levels
● Prince Plaza II 5+1 Basement Levels, Corner De La Rosa and Legaspi St. Makati City
● BSA Mansion, 5.1 Basement Levels, Legaspi Village Makati City
● Tiffany Makati City, Legaspi Village 5+1 Levels Basement
● Care Bldg. Salcedo Village, Makati City 5 Basements
● Salcedo 1, Salcedo Village, Makati City 3 levels Basement
● Lever 1 Bldg. , 5-1 Basement Levels Makati City
● Texas Instruments, Baguio City, as Anchored Retaining Wall
● CitiLand 10 Bldg Multi Storey Basement Makati City
● CitiCorp Mansion Baguio City, as Anchored Retaining Wall
● Le Metropole Multi-Storey Basement, along Buendia Avenue, Makati City
● Trafalgar Bldg. , Multistorey Basement, Salcedo Village Makati City
● Toyota Press Pit Plant Santa City, Laguna For TAISE
● New Bulletin Bldg. , Intramuros as Protection of Historical ancient Buildings, for TAISEI
● National Museum, Luneta, Manila as walls of the 4,000 m3 underground water cistern
● National Museum Luneta Manila as retaining wall protecting the substructure of the old Historical Finance BLDG