Hydraulic and earth engineering – Fluid control – treatment – or containment – Fluid storage in earthen cavity
Patent
1984-07-24
1986-02-25
Taylor, Dennis L.
Hydraulic and earth engineering
Fluid control, treatment, or containment
Fluid storage in earthen cavity
405 53, B65G 500, E21D 1302
Patent
active
045727074
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method in the excavation of caverns in rock, and in particular to the excavation of substantially vertical cylindrical caverns, in which fluids, such as oil products, dry goods, or articles of equipment can be suitably stored.
The object of the present invention is to provide a method by means of which the area adjacent a rock cavern can be drained in a simple and rational manner, thereby to minimise the risk of water leaking into said cavern.
A further objct of the invention is to provide a method by means of which a conical roof space can be blasted in said rock cavern in a simple and rational fashion, such as to enable the rock cavern to be lined thereafter with a waterproof coating.
2. Background Art
Present day rock caverns intended for the storage of oil products have the form of long, horizontal hemispherical cavities, in which the base of the cavity measures 500.times.25 m or more, and the height measures 30 m. Oil stored in such cavities will unavoidably rest on a bed of water, and it has been found that microorganisms thrive and multiply in the intersurface between the oil and water and destroy the oil/oil products to such an extent as to render the same completely useless. When storing refined products in this manner, it has been found necessary to re-refine said products, in order to guarantee their usefulness.
The use of substantially cylindrical, vertical rock caverns has been proposed as a solution to this problem. A description of this proposal is found, inter alia, in SE-B-7901278-7, and in subsequent articles by K. I. Sagefors et al, WP-System, Stockholm, Sweden. In accordance with the aforesaid proposal, when excavating the rock cavern a conical roof cupola is formed from a top heading in the cavity, by first drilling holes outwardly and downwardly along the cylindrical surface of the intended cupola; placing an explosive charge in each of the drill holes and exploding the charges; cutting out one or more transport tunnels which open into the wall of the ultimate vertical, cylindrical cavern; and excavating the rock from said transport tunnels, by drilling vertical blasting holes and blasting the surrounding rock, the rock debris falling to the bottom of the cavern and being removed therefrom. The bottom of the cavern has a downwardly tapering conical form, and merges with an exit tunnel, through which pipes can be drawn and the stored products removed.
In SE-B-7901278-7 it is proposed that a series of holes is arranged in a curtain-like fashion around the whole of the storage plant, or around selected areas thereof, and that the holes are filled with water, to prevent a lowering of the ground-water level, and to prevent the stored product from spreading to the surroundings through cracks, fissures and the like; in other words it is ensured that the storage plant is shielded by water-pressure.
As beforementioned, previous methods for excavating substantially cylindrical rock caverns have entailed drifting a top heading from which subsequent drilling is effected. These methods call for a large number of blasting holes to be drilled, which results in the placing of a heavy and excessive explosive charge, and therewith places the roof structure of the cavern under an unnecessarily high strain. Drifting of the top heading also disturbs and unsettles the rock located above the cavern, with the subsequent risk of impairing the stability and strength of the overlying rock formations.
The discovery that microorganisms thrive and multiply in the interface between the stored product and the water present has led to a demand for the minimum possible amount of water to be present in said cavern. In response to this demand, it has been proposed that the walls of the rock cavern be covered with a waterproof material, said wall coverings consisting of a multi-layer coating which comprises respective layers of gunite, or shotcrete, reinforced gunite, or shotcrete, epoxy resin, glass-fibre fabric, and finally a further layer of epoxy resi
REFERENCES:
patent: 2896417 (1959-07-01), Meade
patent: 2928248 (1960-03-01), Hubbell
patent: 3068654 (1962-12-01), Warren
patent: 4045963 (1977-09-01), Hansson et al.
patent: 4233789 (1980-11-01), Dinardo
patent: 4363563 (1982-12-01), Hallenius et al.
patent: 4474506 (1984-10-01), Sagefors
Boliden Aktiebolag
Taylor Dennis L.
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