RU2558085C1 - Method of driving of vertical mine shafts in flooded unstable rocks - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method includes the formation of ice wall around a shaft outline. Execution of drilling-and-blasting works by drilling the breaking and main blastholes with their subsequent loading by explosive charges and blast firing. Monitoring of stresses in freezing columns in the zones of contact of two rocks with differing physico-mechanical properties. At achievement of maximum allowable values of tension in freezing columns in zones of contact of two rocks with differing physico-mechanical properties in a face between the last row of breaking blastholes and the shaft outline trunk contour two rows of compensation non-charged blastholes are drilled which form pre-outline and outline row of blastholes and located chequerwise with reference to each other. These rows are located at the pre-set distances from the main blastholes and the shaft contour. The centre of each compensation blasthole of the pre-outline row is located between the neighbouring blastholes and at the same distance from them.

EFFECT: decrease of power losses during drilling-and-blasting works inside a shaft contour that allows to increase the speed of its driving.

3 cl, 2 dwg

Description

The invention relates to the mining industry, and in particular to a method of sinking vertical shaft shafts in flooded unstable rocks.

There is a method of sinking vertical shaft shafts in flooded unstable rocks, including freezing rocks at the location of the trunk, creating a waterproofing grouting curtain around the ice-rock fence with subsequent destruction of rocks, their excavation, securing the shaft shaft and cementing the fixed space [1].

The disadvantage of this technical solution is the destruction of freezing columns in the contact zone of rocks with different velocities of the passage of elastic waves that occur when blasting hole charges.

A known method of sinking vertical shaft shafts in flooded unstable rocks, including the formation of an ice-rock fence around the trunk, drilling and blasting, determining the position of the face during the explosion of explosive charges (EX) with the maximum allowable force of elastic waves on freezing columns relative to the contact boundaries of two rocks with various physical and mechanical properties, after which the destruction of rocks is carried out in a mode that provides the magnitude of stresses in the freeze waving columns created by elastic waves equal to or less than the maximum allowable value [2].

This invention prevents the destruction of freezing columns. When carrying out drilling and blasting operations with rock strength above the fifth category according to the Protodyakonov scale, the magnitude of the effect of elastic waves on freezing columns is reduced by changing (decreasing) the mass of explosives at the same time exploded to the maximum permissible value, which reduces the efficiency of the rock destruction process inside the trunk contour. This method is taken by me as a prototype.

The objective of the invention is to increase the rate of penetration of the barrel by reducing the energy loss of the blast wave inside the contour of the barrel while ensuring the safety of freezing columns.

This is achieved by the fact that in the method, which includes the formation of an ice-rock fence around the contour of the trunk, drilling and blasting by drilling cut and drill holes with their subsequent loading with explosive charges and blasting charges, controlling stresses in freezing columns in the contact zones of two rocks with different physical and mechanical properties, as well as mechanized loading of broken rock, mounting a mine shaft with grouting of the fixed space, when reaching the maximum permissible stress values in the deputy in the working columns in the face are drilled at a predetermined distance from the last row of boreholes, compensation uncharged boreholes forming a pre-contour row, the center of each compensation bore of this row is located between adjacent boreholes and at the same distance from them, as well as the contour row of uncharged compensation boreholes, located relative to the pre-contour row of compensation holes in a checkerboard pattern and at a given distance from the barrel wall. The distance between the last row of bore holes and the contour row of compensation holes is determined from the expression:

where d _P is the diameter of the explosive cartridge in jack bore holes .;

k _ZAZH - coefficient taking into account the clamping of rocks, for frozen sandstones is taken in the range from 0.8-0.85, in frozen clay rocks - in the range from 0.65-0.75;

k _G.U - coefficient of geological conditions, taking into account the presence of layers of rocks with different acoustic stiffness, in the absence of contacts is equal to 1; upon contact of sandstone and clay - 0.7; upon contact of sandstones and suspensions - 0.8; upon contact of sandstone and marls - 0.6;

k _SP - rock structure coefficient, ranging from 0.856-1.12, depending on density and fracture.

In addition, when driving a shaft in rocks with different strengths, the energy of shock waves is controlled by changing the diameters of the compensation holes to a value at which the stresses in the freezing columns created by the shock waves are equal to or less than the maximum allowable value.

In FIG. 1 shows an arrangement of drill holes, compensation holes and an ice-rock fence.

In FIG. 2 shows the assembly A of FIG. one.

The method of driving vertical shaft shafts in flooded unstable rocks is as follows.

In the rock mass 1, freeze wells 3 are drilled around the contour 2 of the project shaft, into which freezing columns are placed, followed by connecting them through brine pipes to the freezing station (not shown). After that, active freezing of rocks is carried out, forming an ice-rock fence 4 around the trunk contour by a predetermined amount. Drilling and blasting operations include drilling of 5 hole and 6 drill holes in concentric circles with corresponding radii from the center of the barrel, followed by their charging with explosive charges and explosive charges in accordance with the known scheme. When a shaft is drilled in rocks with different physical and mechanical properties in the contact zone of two rocks with different physical and mechanical properties, the blast hole explodes, the reflected waves are superimposed on the main elastic wave from the contacting surface of two rock layers. When the phases of the main elastic wave and the reflected waves coincide, the amplitude of the shock waves increases significantly, which can cause deformation and destruction of freezing columns, and therefore, destruction of the ice-rock fence. The reflection coefficient of elastic waves from the boundary of two frozen rocks is determined by the speed of propagation of elastic waves in these rocks - C ₁ , C ₂ and the density of each of them - ρ ₁ , ρ ₂ according to the well-known formula:

Since this coefficient can be significant for frozen rocks, for example, for frozen sands and clays the maximum value is 0.37, a significant part of the energy will be reflected and added to the energy of the direct wave, which causes deformation and destruction of the columns.

The practice of building vertical shaft shafts has shown that the destruction of freezing columns often occurs in the contact zone of two rocks with different physical and mechanical properties. In this regard, in the process of drilling a well, one of the known methods is specified - seismic exploration or georadiolocation, the contact boundary of two rocks with different physical and mechanical properties relative to geological exploration data. The choice of a method for determining the position of the boundary depends on the depth of the boundary between two rocks and the given measurement accuracy. The distance from the bottom of the shaft to the boundary between two rocks with different physical and mechanical properties is calculated by the well-known formula:

where C is the propagation velocity of elastic waves in the overlying rock layer;

T ₃ is the signal transit time from the emitter to the contact boundary of two rocks with different physical and mechanical properties and vice versa.

Measurements of column deformations are carried out using strain gauges installed in freeze wells and a measuring unit located on the surface, followed by calculation of stresses in freezing columns. The smaller the distance between the sensors, the higher the measurement accuracy. As the face approaches the boundary between the two rocks, the deformation of the columns increases. The maximum permissible value of deformations in freezing columns depends on the material and the manufacturing quality of pipes for freezing columns. The zone of the bottom position with the maximum allowable force of elastic waves during the explosion of blast-hole explosive charges on freezing columns relative to the contact boundaries of two rocks with different physical and mechanical properties is determined by comparing the measured value of deformations (stresses) in freezing columns and the maximum allowable force of elastic waves acting on freezing columns. Upon reaching the maximum permissible value of deformations (stresses) in the freezing columns, drilling uncharged holes are drilled along a concentric circle relative to the center of the barrel at a given distance from the last row of drill holes, forming a pre-contour row of holes 7. This distance is determined from the expression:

a = 27d _П k _ЗЖ k _G.U. k _{joint venture}

where d _P is the diameter of the explosive cartridge in jack holes;

k _ZAZH - coefficient taking into account the clamping of rocks, for frozen sandstones is taken in the range from 0.8-0.85, in frozen clay rocks - in the range from 0.65-0.75;

k _G.U - coefficient of geological conditions, taking into account the presence of layers of rocks with different acoustic stiffness, in the absence of contacts is equal to 1; upon contact of sandstone and clay - 0.7; upon contact of sandstones and suspensions - 0.8; upon contact of the gerbil and marl - 0.6;

k _SP - rock structure coefficient, ranging from 0.856-1.12, depending on density and fracture.

The center of each compensation bore of the contour row 7 is located between adjacent bore holes and at the same distance from them, and the compensation bore holes of the contour row 8 are staggered relative to the contour row of the compensation bore holes. The distance from the contouring series of compensation holes to the barrel wall is 200 mm for rocks with a strength up to the fourth category on the Protodyakonov scale, and for stronger rocks - 350 mm. In this case, all the bore-holes are cylindrical in shape. Regulation of the energy of shock waves acting on the freezing columns is possible by changing the diameters of the compensation holes from 55 to 60 mm. The presence of compensating uncharged boreholes of the contour and contour series allows one to reduce the amplitude of the blast wave and its velocity outside the borehole contour, since during the explosion of borehole explosive charges, stress concentration occurs on the cylindrical walls of the compensation boreholes, which causes cracks in the rocks between the boreholes with their subsequent destruction in edge area of the trunk. Thus, energy losses inside the trunk contour during drilling and blasting operations are reduced, which ensures a high rate of penetration of the barrel. The location of the pre-contour and contour rows of uncharged holes in a checkerboard pattern relative to each other can also significantly reduce the number of pins on the trunk contour. Reducing the amplitude of the blast wave to the maximum permissible value and its speed outside the contour of the barrel helps prevent the destruction of freezing columns.

The formation of ice-rock fencing around the contour of the trunk, transportation of broken rock to the surface, fastening and grouting of the annulus is carried out according to known technologies using known explosives and technical means.

The method of sinking vertical shaft shafts in rocks is implemented in relation to the conditions of the Sarobinsky deposit during the construction of a cage trunk with a diameter of 8.0 m and a depth of 670 m. The developed layer is represented by deposits of chalk, sand, marl and clay, which are flooded to a depth of 165.4 m. Zone bedding of rocks at a depth of 140 ÷ 150 m is a zone with a high hydrostatic pressure of groundwater up to 5 MPa. To create an ice-rock fence 2.7 m thick and 168 m deep, 34 freezing wells are drilled along a concentric circle with a diameter of 9.6 m. Freezing columns with an external diameter of 144 mm are placed in these wells. Freezing is provided for low temperature (brine temperature -35 ° C) for 180 days. The total cooling capacity of the freezing station is 26.5 MJ. After creating an ice-rock fence of a given thickness, they begin to penetrate the barrel with a blasting method. Drilling and blasting operations are carried out in accordance with the BVR passport, which is calculated, for example, according to the method of N. Pokrovsky. Drilling of cut-in, jack-off and compensation boreholes by a drilling rig, for example, of the BUKS-1M type, is provided. The hole-cut holes are drilled to a depth of 2.2 m, and the jack-off and compensation holes are drilled to a depth of 2 m, with the diameters of the hole-cut and jack-off holes being 42 mm, and the compensation holes - 52 mm. The mass of simultaneously exploded charges is 40 kg, explosive - ammonite 6 LH for rocks with a strength of f = 2 ÷ 3 and rocky ammonite No. 1 for rocks with a strength of f = 3 ÷ 5, the compensation holes are left uncharged. Blasting holes are blasted simultaneously, and blasting holes are produced with a delay of 400 ms. The advancement of the face for the entry is 1.5 m. After blasting, the broken rock is transported to the surface with the help of a grab loader and the barrel is fastened using cast-iron tubing lining, consisting of shaft tubing 1.5 m high with an inclined filling hole of the Shakhtspetsstroy design. To prevent deformation and destruction of freezing columns in the contact zone of two rocks with different physicomechanical properties from the action of elastic waves that arise during the explosion of explosive charges, the contact boundary of sands and clays, as well as sands and marls, is refined using geological exploration data. According to the data obtained, the boundary between sand and clay is in the depth interval 112.6-112.8 m, and sand and marl - 140.8-141 m. Based on practical data, the zones of possible column destruction are in the range from 0.5-2 , 0 m from the boundary of the contact of rocks [3]. For frozen sands and clay, the propagation velocities of elastic waves are C ₁ = 5300 m / s and C ₂ = 3200 m / s, and the density ρ ₁ = 2600 kg / m ³ , ρ ₂ = 2000 kg / m ^3, respectively, for frozen marls C ₃ = 3270 m / s, ρ ₃ = 2200 kg / m ³ . In this case, the reflection coefficient from the boundary of frozen sand and clay, as well as sand and marls, in accordance with the above formula (2) will be k ₁ = 0.37 and k ₂ = 0.36, respectively. With such values of the coefficients k ₁ and k _{2, a} significant part of the energy will be reflected and added to the energy of the direct wave, which can cause the destruction of the columns. In this regard, it is necessary to determine the position of the face at which deformations (stresses) in the freezing columns reach the maximum permissible value. The stresses in the columns are estimated using strain gauges located in freezing wells 3 within 2.5 m above and below the contact boundary of two media and a measuring unit, for example, UTI1. The step of installing strain gauges in the well is selected from the condition that the measurement accuracy should be 5-10 times higher than one step of advancing the face, equal to 1.5 m. In this case, the step is chosen equal to 25 cm. Pipes for freezing columns are made of carbon steel with heat treatment, withstanding pressure up to 20 MPa. The maximum allowable voltage value in freezing columns is a value close to 14 MPa. According to the measurement results, it was found that when the bottom is approached at a distance of 2.5 m from the layer contact boundary to 1 m, the voltage in the freezing columns increases to the maximum permissible value of 14 MPa. After that, to reduce the voltage in the freezing columns, a pre-contour row of compensating uncharged holes is drilled at a distance “a” from the last row of drill holes calculated by expression (1) and equal to a = 27 · 0.036 · 0.82 · 0.8 · 0, 96 = 600 mm. At the same time, the radius of the circle on which the centers of the bore holes of the last row are located is 2.8 m, and the distance between adjacent bore holes is 800 mm. Each compensation hole of the pre-contour row is located between two adjacent bore holes and at the same distance from them. They also drill a contour series of compensation uncharged holes at a distance of 200 mm from the contour of the barrel, since the rock strength is below the fourth category on the Protodyakonov scale. This row is staggered relative to the pre-contour row of compensation holes. With rock strength above the fourth category, the energy of shock waves is controlled by the Protodyakonov scale by changing the diameters of the compensation holes from 55 mm to 60 mm, at which the stresses in the freezing columns created by the shock waves are equal to or less than the maximum permissible value.

Thus, the proposed method of sinking of vertical shaft shafts in flooded unstable rocks allows to ensure a speed of sinking of the trunk of at least 87 m / month. by reducing the energy loss of the blast wave inside the contour of the barrel while preserving the freezing columns.

Information sources

1. RF patent No. 2095574, class. E21D 1/12 of 10/02/1990 “A method for constructing mine shafts in flooded unstable rocks”.

2. RF patent No. 2398967, IPC E21D 1/00, E21D 1/12 dated 07/23/2009 "Method for sinking vertical shaft shafts in flooded unstable rocks" (prototype).

3. Trupak N.G. "Freezing rocks during the construction of vertical shaft shafts", M., Nedra, 1983, p. 126.

Claims (3)

1. A method of sinking vertical shaft shafts in flooded unstable rocks, including the formation of an ice-rock fence around the contour of the trunk, drilling and blasting by drilling cut and drill holes with their subsequent charging with BB charges and blasting charges, monitoring stresses in freezing columns in the contact zones of two rocks with various physical and mechanical properties, as well as mechanized loading of broken rock, mounting a mine shaft with cementing of a fixed space, I distinguish This is because when reaching the maximum permissible stress values in the freezing columns in the contact zone of two rocks with different physical and mechanical properties in the face, compensated uncharged holes are drilled at a predetermined distance from the last row of drill holes, forming a pre-contour row, with the center of each compensation hole of this a row is located between adjacent bore holes and at the same distance from them, and also - a contour row of uncharged compensation holes located relative to the ancestor a line of compensation holes in a checkerboard pattern and at a given distance from the trunk contour. 2. The method according to p. 1. characterized in that the distance between the last row of drill holes and the contour row of compensation holes is determined from the expression:
a = 27d _П k _ЗЖ k _G.У k _СП ,
where d _P is the diameter of the cartridge BB in the bore holes;
k _ZAZH - coefficient taking into account the clamping of rocks, for frozen sandstones is taken in the range from 0.8-0.85, in frozen clay rocks - in the range from 0.65-0.75;
k _G.U - coefficient of geological conditions, taking into account the presence of layers of rocks with different acoustic stiffness, in the absence of contacts is equal to 1; upon contact of sandstone and clay - 0.7; upon contact of sandstones and suspensions - 0.8; upon contact of sandstone and marls - 0.6;
k _SP - rock structure coefficient, ranging from 0.856-1.12, depending on density and fracture. 3. The method according to p. 1, characterized in that when the shaft is drilled in rocks with different strengths, the energy of the shock waves is controlled by changing the diameters of the compensation holes to the value at which the stresses in the freezing columns created by the shock waves are equal to or less than the maximum permissible value .

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