What is a Hydrofraise used for?
A Hydrofraise trench cutter is used to construct deep concrete walls that go down to bedrock through hard and difficult ground.
What is Hydrofraise?
A hydrofraise is a reverse circulation excavation tool which consists of a heavy steel frame with two drive gears attached to its bottom end, which rotate in opposite direction round horizontal axes. Cutter wheels area mounted onto the drive gears.
What is foundation diaphragm wall?
Diaphragm walls are underground structural elements commonly used as retention systems and permanent foundation walls. They can also be used as groundwater barriers.
What is the function of the diaphragm wall?
Diaphragm walls have a static and/or sealing function and can serve as cut-off walls for dams or excavation pits, as foundations or as enclosures of structures. They are executed as concrete or steel-reinforced concrete walls, built from ground level.
What is a bentonite wall?
Bentonite is a naturally-occurring material created by the alteration of volcanic ash in marine environments. Bentonite’s thixotropic properties mean it forms a highly water-resistant gel which, when mixed with additives, can create a permanent barrier to water flow.
What crack width limit would you use to design a diaphragm wall?
Through the theory of diaphragm wall design analysed, the allowable width of structure crack wlim = 0.2 mm is confirmed to be the most important factor which caused the negative design. According to the national codes, the ratio of Ms and Mu should be between 0.73 and 0.89.
What is bentonite slurry?
Bentonite slurry is a combination of sodium bentonite and slurry. Bentonite is implemented for self-hardening mixtures which are then resorted to build cut off walls, grouting mortars, and grouting.
Why is bentonite used in diaphragm walls?
Bentonite slurry is one of the most common excavation fluid used in constructing diaphragm wall. Bentonite slurry shores the trench to stabilize the excavation and forms a filter cake on the slurry trench walls that reduces the slurry wall’s final soil permeability and to reduce ground water flow.
How do you build a diaphragm wall?
Diaphragm walls are one of the most important technologies of special foundation engineering. A diaphragm wall is constructed using a trench excavated in ground and supported by a mud fluids (typically bentonite or polimer mud) until the mud is replaced by concrete, after the steel cage installation.
Which of the following is the diaphragm wall?
TYPES OF DIAPHRAGM WALL Depending on the use of construction materials there are the following types of diaphragm walls: a) Rigid type 1) Reinforced cement concrete. b) Flexible type 1) Plastic concrete, 2) Cement bentonite slurry trench, and 3) Earth backfilled slurry trench.
How slurry works as a wall describe it?
The dense but liquid slurry prevents the trench from collapsing by providing outward pressure, which balances the inward hydraulic forces and also retards water flow into the trench. The guide walls are constructed on the ground surface to outline the desired slurry trench and guide the excavation machinery.
What kind of construction is a diaphragm wall?
Diaphragm wall is a reinforced concrete structure constructed in-situ panel by panel. The wall is usually designed to reach very great depth, sometimes up to 50m, mechanical excavating method is thus employed. Typical sequence of work includes: Construct the guide wall. Excavation to form the diaphragm wall trench.
Which is the best drill for diaphragm walls?
Most recently we have introduced the Cit’Easy. A special Hydrofraise machine, the Hydrofraise XS2, was developed for urban diaphragm walls, which as a rule have moderate thicknesses and depths. Requiring less space and consuming less energy than the conventional Hydrofraise, the XS2 nevertheless offers equivalent or superior drilling efficiency.
How big does a diaphragm retaining wall need to be?
A diaphragm wall is normally constructed in panels ranging in length from 2.8m to 7.0m using purpose built hydraulically or rope operated grabs mounted on a base crane. The grab is used to excavate the panel which is filled with bentonite or polymer to support the open panel as it advances.
How is the Hydrofraise used to cut the ground?
The Hydrofraise uses two counter rotating drums at the base of a frame suspended from a crane to cut the ground. The spoil is removed via a pump which pumps the spoil back to a de-sanding unit.
