Hydraulic and earth engineering – Earth treatment or control – Chemical
Patent
1995-11-08
1998-01-13
Taylor, Dennis L.
Hydraulic and earth engineering
Earth treatment or control
Chemical
405232, 405266, 37348, E02D 518
Patent
active
057071829
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process and a device for exactly holding the vertical excavation direction of a diaphragm wall using a hydraulic diaphragm wall grab cooperating with an excavator and having an outer guide body and an inner body receiving the grab appliance.
Diaphragm walls and sealing walls have become an important component in foundation engineering. Normally, a diaphragm wall is constructed in single segments. In principle their depth is not definite, however, in case of greater depths there is the risk that diaphragm wall elements "run off" which, due to the deviation from the desired vertical position, results in gaps between the segments in the lower region of the wall, impairing the stability of the wall to be built. The construction of diaphragm walls having a depth of more than 40 m requires special experience and measures during excavation, for example, extensive measurements at the open slots. These are excavated without lining and, in case of inhomogeneous soil, tend to deviate from the predetermined vertical direction for this reason.
Usual widths of diaphragm walls amount to 600-800 mm, however, widths of 400-1,500 mm can also be found in construction work, depending on the depth and purpose of the diaphragm wall, In case a diaphragm wall segment deviates from the predetermined vertical direction it is necessary to cut the walls again using. profile chisels, in order to obtain a perfect vertical position of the wall. This process is time-consuming and increases construction expenses; for this reason the site supervision strives to hold the diaphragm wall excavation in the predetermined direction as exactly as possible.
It is known from the prior art to provide diaphragm wall grabs with so-called control plates mounted at the base frame. Such an arrangement is described, e.g., in the Special Print 66 of the Salzgitter gitter Excavators"!, Special appliances for drilling and building activities, by Dr.-Ing. Hans Bartholmai, illustrated on page 6, picture 15.
This equipment is suited to stabilize the vertical position during excavation of a diaphragm wall, however, it is unsuited to compensate an already existing deviation from the predetermined working direction.
It is the object of the present invention to provide a process and a device for exactly holding the vertical excavating direction of a diaphragm wall by means of a diaphragm wall grab, allowing primarily to immediately recognize any deviation from the predetermined excavating direction and to indicate same to the control panel of the diaphragm wall grab operator and secondarily to compensate said deviation by a modification of the direction of the grab.
In a process according to the introductory part of claim 1 this problem is solved according to the present invention by the fact that the vertical position of the inner body and/or guide body is continuously controlled by means of an inclination detector whose signals are transferred to a control unit and that, in case the bodies deviate from the predetermined vertical direction, this deviation is compensated by swivelling the inner body inversely to the deviation, relative to the guide body.
With this process the vertical excavating direction of a diaphragm wall can for the first time be held automatically exact by using a hydraulic diaphragm wall grab. This allows an efficient advance during the excavation of a diaphragm wall by avoiding both the expensive and time-consuming intermittent measuring of the excavated diaphragm wall part and subsequent work; additionally continuously advancing excavation can be carried out at a considerable cost reduction.
According to an embodiment of the present invention it is provided that any possible angular deviation from the vertical position is combined with a depth measuring device related to the diaphragm wall grab, a coordination of deviation and diaphragm wall depth is calculated and that this is indicated to the control panel of the diaphragm wall grab operator.
A device for exactly holding the vertical excavating direction
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patent: 3283230 (1966-11-01), Davies et al.
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patent: 5311683 (1994-05-01), Camilleri
Bartholmai, Special Print 66 of Salzgitter Maschinen AG, "Attachments for Excavators", pp. 1-7.
Stahlund Apparatebau Hans Leffer GmbH
Taylor Dennis L.
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