RU2225479C1 - Restoration method for quarry faces, which were disrupted during exploitation thereof - Google Patents

Abstract

FIELD: mining industry and building industry equipment. SUBSTANCE: method involves graining disrupted area; placing shuttering frame in quarry face toe depression; fixing shuttering frame into face toe depression by anchors; layer-by-layer filling shuttering frame space with concrete composition up to leveling with upper quarry face banquette; advance loading shuttering frame through layer thickness with crushed rock from lower banquette and then from upper banquette; waterproofing upper and lower banquettes after concrete setting-up; removing load. EFFECT: increased width and bearing strength of banquettes of disrupted high steep quarry face areas. 6 cl, 1 ex

Description

The invention relates to the construction and mining and can be used to restore the ledges of the quarry during its operation.

In the event of collapse of the ledge section, which is the capital congress and located in the limiting contour of the current quarry, re-registration of the side section is ineffective. In this regard, there is a need to restore the damaged sections of the transport berms for the period of operation of the quarry. A variety of designs of retaining concrete walls are known, including those used in industrial and hydraulic structures, as well as protective structures and methods for their calculation, described in the works of N.K. Snitko, E.L. Galustyan. The walls in question can be divided into two types:

- Thin walls with great penetration into the ground;

- massive walls with a shallow laying in the ground.

Massive and thin walls are mainly located on the slope itself, usually they support the soil, and do not restore the damaged part of the slope of the ledge (Static and dynamic soil pressure and calculation of retaining walls. State Publishing House of Literature on Construction, Architecture and Building Materials. Leningrad, 1963, Moscow , 109-110 pages, 129-132 pages, Gosstroyizdat, 1963). With this arrangement, the wall will narrow the width of the berm, which will interfere with the operation of technological transport and increase the load on the underlying ledge. Given that the escarpment of the ledge is complicated by rocks that are broken by irregular misaligned cracks, the use of thin walls without additional reinforcing measures to prevent intensive destruction of the escarpment becomes impossible. In addition, the negative effect of external factors on the ledge - the load from transport and hydraulic support from the side of the massif, will also affect the thin wall itself, since it is usually small in width compared to the length, so its curvature (bulging) cannot be neglected. Violation of the strength and integrity of the wall itself will affect the stability and strength of the ledge itself.

Based on the foregoing, we can say that this design is ineffective for restoring the bearing capacity of disturbed sections of high ledges.

The closest in technical essence and the achieved result is a method of attaching soil slopes, including installing the formwork frame in the recess at the base of the ledge, securing it with anchors and pouring concrete mortar into the formwork space (German application No. 2618459, E 02 D 17/20, Method for strengthening soil slopes / priority of Japan on 05/14/1975, declared by Germany on 04/27/1974, publ. 11/25/1976). For fastening, a shuttering frame is used, consisting of two flexible side walls located in parallel, and reinforcement is installed between the side walls, which is connected to the side walls in the form of a simple finished block. Concrete with a low water-cement ratio is laid on the sides of the walls, so that they are completely embedded in the concrete. The result is a flexible design that strengthens the soil slope and prevents collapses.

The disadvantage of this method is the low bearing capacity of the structure due to the impossibility of laying a flexible mesh structure along a large fault. This design, located directly on the ledge of the slope at a height of up to 30 m, will accept the main loads arising from the hardening of concrete on itself, since it cannot rely on the slope, which as a result will require a significant increase in strength and will not prevent without additional measures further destruction of the formed fault. As a consequence of this, a significant increase in metal consumption and a higher cost of construction will be required. In addition, when applying concrete to a flexible mesh structure located on a slope of a ledge with a height of up to 30 m and a large angle of slope, it is difficult to keep the concrete from flowing out.

The aim of the invention is to increase the bearing capacity and the restoration of the width of the berms of disturbed areas of high steeply ledges.

This goal is achieved by the fact that in the method of restoring the broken ledges during the operation of the quarry, including installing the formwork frame in the recess at the base of the ledge, fixing it with anchors and pouring concrete mortar into the formwork space, before installing the formwork frame, drain the damaged part of the ledge, pouring the concrete solution lead in layers, until leveling with the upper berm of the ledge with the leading load of the formwork to the height of the layer, and after the concrete mortar hardens, roizolyatsiyu upper and lower berms ledge and removal prigruza.

And crushed stone is loaded first from the lower berm of the ledge, then from the upper berm of the ledge.

Drainage of the disturbed area allows eliminating the ingress of flood water along the internal cracks of the ledge and, as a result, the occurrence of dangerous hydrostatic pressure between the wall and the rock, which can lead to impaired stability, bearing capacity and, when collapsed, to reduce the size of the berms.

Layer-by-layer pouring of concrete mortar allows for laying mode with intervals of hardening (for setting concrete strength), which increases the bearing capacity of the disturbed section of the ledge and the ledge as a whole.

The leading load of the formwork frame allows you to balance the load from the concrete mortar, closes the voids between the formwork and the slope to prevent leakage of the slope. Concreting is carried out before alignment with the upper berm of the ledge, which leads to the restoration of its width and ensuring the operating conditions of the technological transport.

Waterproofing the upper and lower berms of the ledge allows eliminating the ingress of flood water from the berms and the occurrence of dangerous hydrostatic pressure between the wall and the rock, as well as reducing the strength properties of the rocks at the base of the ledge. Because in the fault zone there are vertical cracks, then even after the restoration of the ledge section, there remains the danger of flooding in them, which leads to water cut of the rocks and the manifestation of hydrostatic pressure on the concrete wall. To eliminate the negative manifestations, waterproof the upper, and after harvesting the cargo and lower berm.

Due to the high height of the ledge, the gravel is loaded first with the lower berma of the ledge, and then with the upper by bulldozer transshipment.

The structural components of the formwork frame were calculated based on the conditions of the stability of the slope in the fault zone under the action of a load from transport, the resistance of the base to bulging, the stability and strength of the wall, taking into account hydrostatic pressure forces at a water cut level of 10 m, as well as the strength of the formwork elements during concreting. The thickness of the cargo layer was also calculated.

As a result of the implementation of the method, a fixed ledge design with a restored bearing capacity and width is obtained.

Figure 1 presents a vertical section of the slope of the ledge in the limiting position, which shows the current state of the fault;

figure 2 is a top view of figure 1 is a section of the same ledge with a crack;

figure 3 shows a section of a reinforced ledge;

figure 4 presents the installation diagram of the formwork frame on the slope of the ledge.

Concrete implementation example

Reinforcement work is carried out on the ledge of 1 quarry. Currently, the ledge is in the ultimate position, at an angle of 75 degrees, 30 m high, the width of the fault is up to 10 m, the depth of the fault is 5 m.

One of the main reasons that affected the escalation of the escarpment of the ledge is crack 2, which contributed to the formation of a large fault 3 (Fig. 2, 1) of great height.

The slope is composed of rocks that are broken by irregular misaligned cracks. In the summer, the fracture zone is characterized by increased water cut and poor ability of the rocks to collapse.

Re-registration of the damaged section of the side of the quarry is not considered in view of the location of the ledge in the extreme position.

The restoration of the ledge is due to the complete concreting of the damaged part. For this, the following parameters were calculated: the angle of inclination of the base of the wall is 15-25 degrees, the allowable height of the hydraulic support is 10 m.

Before starting recovery, preparatory work is carried out.

The berms are cleaned and the escarpment of the ledge is mechanized using a backhoe, frontal loader, and a bulldozer-ripper. After a mechanized frill, the individual remaining overhangs, “visors” are manually removed by a team of mountain slope drifters.

An excavator along the entire length of the disturbed section of the upper berm conduct a recess of 1 m for subsequent waterproofing.

An excavator is excavated at the bottom edge of the pit with a depth of 1 m, a fault width of 10 m, with a slope of 15-25 degrees in the direction of the slope.

Symmetrically to fault 3 at the base of the ledge, recesses are prepared with a section of 30 × 30 cm, a depth of 0.5 m at a distance between the centers of the recesses of 5 m

To drain water from the escarpment of the ledge, in the lower part of fault 3, a fan is installed horizontally, with a slight slope towards the excavation part of the quarry, pipes 4 5-6 m long and 80-100 mm in diameter. The open ends of the pipes go to the escarpment of the ledge (figure 3), they are closed with wooden corks.

Upon completion of the preparatory work, the formwork frame is installed (Fig. 4).

The formwork frame includes the following elements:

5 - guide formwork (channel number 22);

6 - rods;

7 - anchor;

8 - timber (pine timber with a section of 200 × 200 × 500 mm).

Guide formwork 5 is installed in the preparatory recesses with an emphasis on the slope at the same angle of 75 degrees, they exceed the height of the ledge (the lower part of the channel base is installed in the prepared recesses). In the upper part and along the entire height of the guide formwork 5 are connected with each other using rods 6.

The installed formwork frame from the formwork guides and rods is fixed on the upper berth using anchors 7. After the formwork frame is installed, the beam 8 is placed in the frame to a height of 1 m and filled with concrete mortar for the formwork space (to this height).

The estimated proportion of the concrete mortar components by volume is 3.8: 1: 7.3: 10.5, respectively cement: water: sand: aggregate.

To prevent bulging of the formwork, it is loaded from the outside with a clamshell loader with crushed stone with a particle size of 20-70 mm. After lifting the formwork to a height of more than 15 m, the gravel is loaded with a forklift from the upper berm. The work is carried out in layers of 1 m in height and incubated for at least 24 hours for setting concrete mortar. Concrete is poured before alignment with the upper berm of the ledge.

After hardening of the concrete solution (approximately 26 days), the upper berm is waterproofed. To do this, put clay in the recess and roll it with motor vehicles. After the final hardening of the concrete mortar, the load is removed and similarly to the waterproofing work on the upper berm, they are carried out on the lower berm. At the end of all work, drill plugs from pipes 4 to drain water.

Claims (2)

1. A method of restoring broken benches during the operation of the quarry, including installing the formwork frame in the recess at the base of the step, securing it with anchors and pouring concrete into the formwork space, characterized in that before installing the formwork frame, the damaged area is drained, concrete mortar is poured in layers , before alignment with the upper berm of the ledge, with the formwork advancing to the height of the layer, and after the concrete mortar hardens, waterproof the upper and lower her berm ledge and removal of the load. 2. The method according to claim 1, characterized in that the gravel is loaded first from the lower berm of the ledge, and then from the upper berm of the ledge.

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