Shaft excavation method
AssigneeTrigon Geoducts Limited
InventorNeil Reid
Life of this patent
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Abstract
A method for sinking a shaft having a wide diameter e.g. 4 meters. A concrete diaphragm wall is formed with five radially inwardly extending sections (12), in each of which a guide hole (13) is formed. Five outer boreholes are drilled to depth using the guide holes and a central borehole (14) is also drilled to depth. The ground within the wall is excavated to rock level. Vertical cuts are made between adjacent outer boreholes (14) and between the central borehole (14) and the outer boreholes (15) using a wire (19) saw cutter. Cross cuts are then made to form separated segments (33) of rock which are removed sequentially. This is repeated progressively downwards to the required depth.
Claims15
A method for excavating a bore through rock which comprises:
- drilling an inner borehole, drilling a series of outer boreholes surrounding said inner borehole;
- cutting the rock material between first and second adjacent outer boreholes to form an outer cut;
- cutting the rock material between said inner borehole and each of said first and second outer boreholes to form two radial cuts;
- said outer cut and two radial cuts thereby defining a first rock segment;
- cutting a cross cut through the first rock segment to join said outer and radial cuts, thereby freeing the first rock segment;
- removing the first rock segment;
- forming further similar outer cuts, radial cuts and cross cuts to free further rock segments;
- removing the further rock segments;
- and repeating the cutting and removal procedures progressively along said bore until the required extent has been attained.
Dependencies are inferred from the claim text.