CS258547B1 - The support feet ee have increased efficiency against tearing of the reinforcement - Google Patents

Abstract

Support feet to prevent the pit reinforcement from being torn off, especially during excavation and deepening of pits, are formed by non-continuous segments located around the perimeter of the pit and connected to the reinforcement or forming part of it.

Description

The invention relates to an abutment foot with increased effectiveness against peeling of the pit reinforcement, in particular during excavation and deepening of pits.

The hitherto known design of the pit support feet consisted in the fact that, according to static considerations, the feet were situated as a continuous wreath around the perimeter of the pit. The distance of the supporting feet was determined by the difference between the friction of the reinforcement and the rock mass and the weight of the reinforcement. For example, if the friction between the rock and the reinforcement has been lost as a result of rock rocking, the reinforcement hung in the pit practically in the pit and only held the tensile strength of the reinforcement material until the space for building the support foot was reached. At a statically justified greater distance between the feet, part of the pit reinforcement could also be torn off. Currently, the only protection against this phenomenon is to reduce the spacing of the support feet below the statically necessary limit. This entails increased excavation costs and technological difficulties in establishing feet in poorly stable rocks.

The abovementioned drawbacks are remedied by support feet with improved anti-rupture efficiency according to the invention, which consists in that they consist of continuous segments located around the perimeter of the pit and connected to or forming part of the reinforcement.

The support feet extend vertically in adjacent reinforcing rings, but may also be dispensed with omitting one or more reinforcing rings. The exact placement of the support feet in the reinforcement ring and in the vertical direction and their dimensions are determined for given mining-goelogical conditions by excavation technology and reinforcement by calculation.

The spaced support feet provide increased effectiveness of each reinforced ring or group of reinforcement rings against the shear of the pit reinforcement and the rock mass, thereby detaching the pit reinforcement especially during excavation. The invention enables to apply technologies in which the nature of the rock and working conditions cause a significant reduction or loss of friction between the reinforcement and the rock mass, in which it is reinforced with the excavation process at the bottom of the pit. It is particularly suitable for monolithic concrete and reinforced concrete reinforcements, and is also suitable for tybic, block, panel and block-panel reinforcements.

The invention makes it possible to apply conventional excavation technologies, without the need for special procedures, under conditions characterized by low friction between the pit reinforcement and the rock mass (e.g. formed by clay-like rocky rocks) and under conditions where for the sake of stability it is difficult to implement.

The accompanying drawings show an exemplary embodiment of the support feet according to the invention, wherein in FIG. 1 a plan view and FIG. 2 show a reinforcement consisting of a series of reinforcement rings provided with support feet according to the invention. Figures 3 to 7 show in longitudinal section the reinforcement of the pit and the individual phases of the execution of the monolithic concrete reinforcement with the segments of the supporting feet. Figure 3 shows an embodiment of the boreholes for receiving the charges in the grip and for breaking the support foot, Fig. 4 the situation after blasting, Fig. 5 the beginning of the reinforcement, Fig. 6 the final reinforcement and Fig. 7

The non-continuous segments 2 of the support feet are part of the rings 3, 5 or are firmly connected thereto. In the exemplary embodiment, it is contemplated to use four non-continuous support foot segments 2 in each second reinforcement ring, with the non-continuous segments 2 not being superimposed. However, the number of segments 2 is always greater than or equal to 1 the spacing of the reinforcement rings 3,5 ^{in the} range from 1 to 20 times the height of the reinforcement ring and the height of the segments 2 ranges from 0.2 to 20 times the height of the reinforcement ring.

When reinforcing the monolithic concrete reinforcement using blasting work, the boreholes for receiving the charges are drilled in the grip 2 of FIG. 3. The distance -j is maintained between the end of the pit reinforcement and the cleaned bottom of the pit. Drill bores are drilled from the bottom of the pit along with the holes in the bottom of the pit.

According to FIG. 5, the rock is partially removed from the fin and monolithic concrete reinforcement can be carried out. Simultaneously with the reinforcement of the pit, reinforcement of the broken-out areas of the support feet according to Fig. 6 is carried out.

Claims (3)

Supporting feet with increased effectiveness against peeling of pit reinforcement, characterized in that they consist of continuous segments (2) located around the perimeter of the pit and connected to or forming part of the pit (1). Support feet according to claim 1, characterized in that the number of segments (2) in the reinforcement ring is greater than or equal to 1 and the distance of the reinforcement rings (3, 5) with one or more segments ranges from 1 to 20 times the height of the reinforcement ring. Support feet according to Claims 1 and 2, characterized in that their height is in the range from 0.2 to 20 times the height of the reinforcement ring.