The most popular use of a diaphragm wall is for the construction of multilevel basements and for top –down building construction method. The trenching process of this diaphragm wall system is aided by bentonite fluid support. During the excavation process bentonite is introduced and recycled during the construction process. Bentonite is used during the excavation process to facilitate the removal of the cuttings when using the trench cutter, until reaching desired depth. This is later replaced by placing concrete in the trench via the tremie method. Bentonite is returned to holding tanks on site to undergo treatment and reuse.
The diaphragm wall system is a fantastic solution compared to any other conventional retaining wall systems because of increased water tightness by minimizing vertical joints. The use of the diaphragm wall system is to alleviate issues in constructing underground tunnels along heavy public presence, deep basements without endangering the stability of the foundations of the nearby buildings. Diaphragm wall system can be applied to water storage, sewage disposal shafts, security vaults, pits, and wharves, containment of contaminated area and control of toxic effluents travelling underground.
Diaphragm wall ancillary structure comprises of de-sanding equipment, silos, holding tanks, transfer pumps, mixer tanks and compressors.
- Ideal for top down construction projects.
- Can be installed in virtually all soil conditions including high strength rock.
- Reduced noise and vibration compared with other shoring techniques such as sheet piling.
- Very accurate method of construction with high tolerance levels.
- Removes the requirement for dewatering the site.
- Can be used in the immediate vicinity of existing buildings.
- Can be designed to carry structural loads thereby reducing the foundation costs.
Scope of Works
Scope of Works
Diaphragm Wall Construction for the proposed residential development at 330 Church Street, Parramatta, NSW. The proposed development will comprise two residential towers over a common podium level and four levels of basement carparking over the main rectangular portion of the site with the footprint of the basement extending to the eastern, western and southern boundaries, and set back between about 9m and 12m from the northern site boundary. The site is located within near level terrain on the south bank of the Parramatta River. Bulk excavations to a maximum depth of about 12m below existing surface levels to be carried out following the completion of the Diaphragm wall.
The work was carried out for Karimbla Construction Services Pty Ltd (Meriton Group)
Scope of Works
Design and construction of the diaphragm wall system with two rows of temporary rock anchors through the wall, which include:
Diaphragm wall: 49 panels x 640mm wide x 2800mm-7000mm length x 12m–13m depth
Temporary anchors: 2 rows x 243 rock anchors x approx. 14m-23m length
- Design works for the diaphragm wall.
- Removal of 40 existing old reinforced concrete piles from the location of the diaphragm wall.
- Design and construct Guide Wall.
- Supply and installation of all concrete, reinforcing steel, anchor blockouts and couplers.
- Supply and installation of Inclinometer system.
- Design, install and test all anchors.
- Installation of standpipe piezometers and monitoring of groundwater levels.
- Monitoring the performance of the southern boundary shoring using the inclinometers and survey monitoring points.
- De stress the temporary anchors.
Concrete used: 50MPa for DW panels (volume 2,650m3)
25MPa for Guide Wall (volume 370m3)
Reinforcement: 200 ton