GB1314933A - Methods and apparatus for excavating trenches and casting diaphragm walls - Google Patents

Abstract

1314933 Bucket ladder excavators; barrier walls in permeable strata P MORNER 5 Oct 1970 10464/71 Divided out of 1310393 Headings E1F and E1H A trench 1 for the subsequent construction therein of a wall is excavated by a bucket chain excavator 2 that is advanced along the line of the trench by the hydrostatic pressure differential on a sealing structure 3 which supports the excavator and, behind the excavator, slidingly and sealingly engages with the walls and the foot of the trench to define in the trench two spaces in which liquid is maintained in the rear space at a higher level than in the front space. The liquid may be a thixotropic liquid and the pressure differential may be created and maintained when the excavator and sealing structure are entered into the earth at the beginning of a trench by pumping or by bailing by the buckets of the variable width excavator when the excavator is started up. Preferably the sealing structure is a steerable, open front and ended box of less width than the width of the trench and is provided on its sides with flexible sealing means for forming seals between the box and the trench sides. The rear face of the box may be such as to form a concrete joint-defining shuttering in the casting of a concrete wall in the trench and may be provided with openings enabling fluid to be introduced to the interface between the box and the cast concrete to facilitate freeing of the box from the concrete as the concrete sets. In an alternative embodiment of the box the shuttering device of Specification 1310393 may be secured to the rear face of the box.