Determination of the dimensions of the cross-section of the working in the light. Calculation of the cross-section of the working in the clear Area of ​​the cross-section in the drive

1. Selecting the shape and calculating the dimensions of the cross-section of the mine

When carrying out workings, two types of mining operations are distinguished: main and auxiliary.

The main mining operations are those that are carried out in the face of the working and relate directly to the sinking and support of the working.

Auxiliary operations are called operations that provide normal conditions for performing basic tunneling operations.

The cross-sectional area of ​​the mine working depends on the purpose and dimensions of the equipment located in it. Distinguish between the cross-sectional areas of horizontal workings in the clear, in the rough and after driving. The clear area is determined by the dimensions of the working before the support minus the areas occupied by the ballast layer and the ladder in the section of the working. The rough area is the projected area to be drilled. When determining this area, the areas occupied by the support, the ballast layer, the ladder and the tightening (with frame supports installed in a run-up) are added to the area in the light. The actual area that is obtained as a result of the development, usually 3-5% or more exceeds the design area.

The cross-sectional dimensions (width and height) of haulage workings depend on the overall dimensions of haulage cars and electric locomotives, on the rail tracks, the way workers move around the workings and the amount of air supplied for ventilation.

If there are railways in the working area for the movement of people, a track (passage) with a width of at least 700mm is provided, which must be maintained at a height of 1800mm from the level of the ladder (ballast layer).

Based on specific conditions: f = 16; stability - medium; service life of the mine - 16 years, choose the vaulted form of the mine, sprayed with concrete

1. Calculate the cross-section of the working height.

a. Height of the structure of the rail track h 0, mm

h 0 = h b + h w + h p + h p, mm;

Where: h 0 - the height of the upper structure of the working path, is selected with the norms stipulating the EPB, mm;

h b - the height of the ballast layer, mm;

h p - height of the lining under the rail, mm;

h p is the height of the rail track, mm;

h 0 = 100 + 420 + 20 + 135 = 375 (mm).

2. Height of the rolling stock h, mm

3. Height of the straight-walled section of the mine.

h 1 = 1800 (mm).

4. Clearance height.

h 2 = h 1 + h b + 1 / 3h w, mm;

h 2 = 1800 + 135 + 20 + 1/3 * 120 = 1995 (mm).

Where: h 1 - the height of the straight-walled section of the mine, mm;

h b - the height of the ballast layer, selected with the norms providing for the EPB, mm;

h w - the height of the sleeper bar, mm;

5. Working height in blacker.

h 3 = h 0 + h 1, mm;

h 3 = 375 + 1800 = 2175 (mm).

6. Height of the vaulted ceiling in the clear.

h h = 1/3 * B, mm;

h h = 1/3 * 2250 = 750 (mm).

7. Height of the vaulted ceiling in black.

h 5 = h h + T cr. , mm;

h 5 = 750 + 50 = 800 (mm).

8. The width of the working in the clear is calculated.

B = n + A + m, mm;

B = 200 + 1350 + 700 = 2250 (mm).

Where: B - working width in the clear, mm;

n is the gap between the support and the rolling stock, mm;

A is the width of the rolling stock, mm;

m - free passage for people, mm;

9. Working width in black.

B 1 = B + 2 * T cr. , mm;

B 1 = 2250 + 100 = 2350 (mm).

10. Cross-sectional area in the clear.

S St. = B * (h 2 + 0.26 * B)

S St. = 2250 * (2745 + 0.26 * 2250) = 7.4 m 2

11. Cross-sectional area in blacker.

S black = B 1 * (h 3 + 0.26 * B 1)

S black = 2350 * (2960 + 0.26 * 2350) = 8.3 m 2

12. The speed of the air flow.

V = Q air / S c in, m / s;

V = 18 / 7.4 = 2.4 m / s;

Where: V is the speed of the ventilation jet along the development, regulated by safety rules, m / s;

Q air - the amount of air passing through the mine, m 3 / s;

S c in - the cross-sectional area of ​​the working in the clear, m 2;

Since V = 2.4 m / s, then 0.25? V? 8.0 meets the requirements of the EPB, therefore, this section is calculated correctly.

13. Cross-section in penetration.

S pr = 1.03 * S black, m

S pr = 1.03 * 8.3 = 8.7 (m)

Depending on the physical and technical properties of the rocks, the service life of the mine, the possible impact of the cleaning work, the cross-sectional shape, materials and type of support are selected ...

Selection and justification of technology, mechanization and organization of the human walk

For this production we get special. profile SPV-17. We choose specials. profile by economic factor. For specials The SVP-17 profile has the following characteristics: = 18774, which corresponds to the interval = 18700 - 20700. W (1) = 50.3 P (1) = 21.73 Table 2 ...

The choice of the method of protection and type of support for mine workings

Figure 2.1 shows the location of the workings relative to the rocks enclosing the coal seam. From the point of view of protection of production, it is undoubtedly beneficial to use roadheader to carry out this development ...

Hydraulic calculation of the unit of hydraulic structures

Determination of the cross-sectional dimensions is reduced to determining the width along the bottom and the depth of filling according to the given parameters (flow rate Q, slope i, roughness n and slope m) ...

Double-track crosscut

When developing a development project, the issue of choosing the shape and size of the cross-section is the most important. For horizontal exploration workings, rectangular-vaulted and trapezoidal sectional shapes are set as standard ...

Organization and conduct of mining exploration work

Since the task does not specify the selection of a technological sample, we will bring Sm to the nearest standard in accordance with GOST: 1) based on the fact that the depth of the pit is 30 m ...

Underground mining

We determine the cross-section of the main vertical shaft using the formulas and refine it according to Table 4.2: SB = 23.4 + 3.6 AG, (5) where AG is the annual production capacity of the mine, million tons. SB = 23.4 + 3.6 1 , 4 = 28.44 m2 ...

Carrying out mine workings violates the stable stress state rocks... Zones of increased and decreased stresses are formed around the working contour. To prevent the rocks from collapsing, the workings are fastened ...

Mining exploration

4.1 Calculation of the cross-sectional area of ​​a trapezoidal excavation Determination of the dimensions of the excavation in the clear. Width of one-track working at the level of the rolling stock edge: B = m + A + n1, m Where: m = 0 ...

Since the Bremsberg mine has a service life of 14 years, it is recommended to carry out the development of an arched section, fasten it with an arched frame support and reinforced concrete tightening ...

Technological design for horizontal underground mine workings

The shape of the cross-section of the working is selected taking into account the structure and the material of the support, which in turn are determined by the stability of the rocks in the sides and roof of the working ...

Tunnel development technology in hard rocks

1. The amount of air that must pass through the mine during its operation is determined: (1) where is the coefficient taking into account the uneven delivery of air, is coal mining at the sites ...

For open exploration workings, substantiate the method of driving, the equipment used and, in accordance with the angle of repose of rocks, select and justify the shape and dimensions of the cross-section, taking into account the design depth of the working.

For underground mining and exploration workings, substantiate the method of driving and the corresponding mining equipment, select and justify the shape and dimensions of the cross-section of the working in the open.

Depending on the physical and mechanical properties of rocks, as well as on the basis of the dimensions of the transport and technological equipment(electric locomotives, trolleys, loading machines), taking into account the dimensions of the clearances provided for by the safety rules (PB) during geological exploration, the dimensions of the cross-section of mine workings in the light are determined. The dimensions of the workings in the sinking are determined taking into account the thickness of the lining and ties, as well as the height of the track device (ballast, sleepers, rails).

Mine workings can be carried out with or without support. Wood, concrete, reinforced concrete, metal and other materials are used as fasteners. Sectional shape can be: rectangular, trapezoidal, arched, round, elliptical.

Horizontal and inclined exploration workings have, as a rule, a short service life, therefore the main type of support is wood, the section shape is trapezoidal. When driving without fastening, the shape of the section is rectangular-vaulted.

For a trapezoidal section of a mine working with rail transport ( rice. 1) it is recommended to calculate the cross-sectional area of ​​the mine in the following sequence.

The dimensions (width and height) of the used electric locomotive or trolley (for manual hauling) determine the width of a single-track working in the clear at the level of the edge of the rolling stock:

B = m + A + n`

and the width of the double-track working:

B = m + 2A + p + n`

m- the size of the gap at the edge of the rolling stock, mm(taken equal to 200 - 250 mm);

p- the gap between the compositions, mm (200mm);

n`- the size of the passage for people at the edge of the rolling stock, mm:

n` = n + * ctg ;

n- the size of the passage at a height of 1800 mm from the level of the ballast layer, equal to at least 700 mm;

h - the height of the electric locomotive (trolley) from the rail head, mm;

h a- the height of the track superstructure from the ballast layer to the rail head, equal to 160 mm;

83 0 - the angle of inclination of the racks, adopted by GOST 22940-85 for exploration workings.

Working height from the rail head to the top in the case of using contact electric locomotives (up to the settlement of the support):

h 1 = h kn. + 200 + 100,

h kn.- suspension height of the contact wire (at least 1800 mm);

200mm- the gap between the contact wire and the support;

100mm- the value of the possible settlement of the support under the influence of rock pressure.

With other types of transport, the height h 1 determined by the graphical construction, taking into account the gap C between the transport equipment and the ventilation pipeline: when transporting battery electric locomotives 250 mm, with manual haulage - 200 mm.

When transporting a battery electric locomotive:

h 1 = h + d t + 250 + 100,

where h - electric locomotive height, mm;

d t- diameter of the ventilation pipeline, mm.

Height h 1 v general case should not be less than the height of the loader with the bucket raised (for PPN-1s, this height is 2250 mm) minus the height of the ballast layer, i.e. h 1 2250 mm.

Opening width across the ballast layer:

l 2 = B + 2 (h + h a) * ctg ;

Opening width across the roof:

l 1 = B - 2 (h 1 - h) * ctg ;

Working height from the ballast layer to the support after settlement:

h 2 = h 1 + h a;

Cross-sectional area of ​​openings after settlement:

S sv = 0.5 (l 1 + l 2) * h 2;

Rough working width along the roof (when fastening in a staggered manner with tightening the sides):

l 3 = l 1 + 2d,

where d - support post diameter (not less than 160 mm).

Working width on the soil in the rough when fastening in staggered directions with tightening the sides:

l 4 = B + ,

where h v= 320mm- height from the working soil to the rail head:

h c = h a + h b,

where h b - ballast height.

Working height from soil to support (before settlement):

h 3 `= h 3 + 100,

where ... h 3- the height of the excavation from the soil to the upper stand (after settlement).

Rough working height before settlement in the presence of tightening:

h 4 `= h 3` + d + 50,

where d- diameter of the fastening timber, mm;

50mm- tightening thickness.

Working height after settlement:

h 4 = h 4 `- 100

Cross-sectional area of ​​the working in the rough before settlement:

S 4 = 0.5 (l 3 + l 4) * h 4 `

Vertical draft equal to 100 mm, allowed only with wooden lining.

In the workings, the laying of wooden sleepers and the laying of the track from rails are used P24 for trolleys up to 2 m 3... When carrying out exploratory workings, trolleys are used VO-0.8; VG-0.7 and VG-1,2 with a capacity of 0.8, respectively; 0.7; 1,2 m... When manually rolling with trolleys VO-0.8 and VG-0.7, as well as AK-2u electric locomotives use rails P18... The sleepers are laid in a ballast layer with a thickness of 160 mm by immersing them in 2/3 of its thickness.

With a rectangular-vaulted shape, the height of the working in the clear is made up of the height of the wall from the level of the ballast layer and from the height of the vault ( rice. 2).

Rough working height H is defined as the clear height plus the thickness of the lining in the vault with monolithic concrete lining or plus 50 mm with sprayed concrete, anchor (rod) and combined support. The height of the wall from the level of the rail head to the heel of the arch h 1 during transportation by battery electric locomotives, it is determined depending on the height of the electric locomotive. The height of the workings during transportation by contact electric locomotives must satisfy the conditions under which the minimum clearances are provided between the electric locomotive (trolley) and the support, as well as between the pantograph and the support.

The height of the vertical wall from the tapa level to the heel of the arch h 2 = 1800mm... The height of the vault h 0 are taken depending on the coefficient of rock hardness on the scale of M.M. Protodyakonov.

For monolithic concrete lining with a strength coefficient f =3:9, h 0 = B / 3.

For sprayed concrete and roof bolting and in unsupported workings f 12 ,h 0 = B / 3, and at f 12, h 0 = B / 4.

The curve of a three-center (box) vault is formed by three arcs: axial - R and two side ones - r... The radii of the vault depending on its height:

Arch height h 0 B / 3 B / 4
Axial arc radius R 0,692 0,905
Side arc radius r 0,262 0,173

Working width design B 1 with concrete lining, it consists of the width of the working in the clear and doubled the thickness of the lining, and in the case of sprayed concrete, anchor and combined lining, it consists of the width of the working in the clear plus 100 mm.

Single-track clear width:

B = m + A + n

Open double-track working width:

B = m + 2A + p + n,

where n = 700mm; p = 200mm.

Height of the vertical wall of the mine working from the rail head:

h 1 = h 2 - h a = 1800 - 160 = 1640mm.

Rough working width with sprayed concrete and roof bolting:

B 1 = B +2 = B + 100,

where = 50mm- the thickness of the lining, taken in the calculation.

Cross-sectional area of ​​the working in the clear at the height of the vault h 0 = B / 3:

S St. = B (h 2 + 0.26B),

at h 0 = B / 4: S sv = B (h 2 + 0.175B),

where h 2 = 1800mm - the height of the vertical wall from the level of the ladder (ballast layer).

Height of the wall from the working soil:

h 3 = h 2 + h b = h 1 + h B.

Light output parameter at h 0 = B / 3:

P B = 2h 2 + 2.33B,

at h 0 = B / 4: .P B = 2h 2 + 2219B

The cross-sectional area of ​​the working out in the rough with sprayed concrete, anchor, combined support with h 0 = B / 3:

S h. = B 1 (h 3 + 0.26B 1),

at h 0 = B / 4: S h = B 1 (h 3 + 0.175B 1).

After determining the cross-sectional area, we take GOST 22940-85 the nearest standard section and write down its dimensions for further calculations. According to this standard, only the cross-sectional area of ​​the working in the clear is determined, and the cross-sectional area is roughly set depending on the adopted section shape, type and thickness of the support according to the above formulas.

In the table 1 shows the typical cross-sections and basic equipment adopted for calculating the cross-section in the clear, as well as the dimensions of the basic vehicles.

Pits by depth are conventionally divided into shallow (up to 5 m), medium (5 - 10) and deep (up to 40 m). The depth of the pits depends on the stage of exploration and geological conditions. Depending on the physical and mechanical properties of the rocks, the method of penetration and the structure of the support, the pits are round and rectangular. With increasing pit depth, the clear cross-sectional area increases. Pits up to 10 m usually have one compartment, and with a depth of up to 20 m can be with two branches. Typical sections (GOST 41-02-206-81), it is planned to drill pits with a clear cross-sectional area from 0.8 to 4 m 3 and geometric dimensions (Table 2).

The cross-sectional shape of a horizontal mine workings depends mainly on the type of rock lining used to protect the workings from destruction under the pressure of the surrounding rocks and to maintain the required cross-sectional area for the entire period of exploration work. When carrying out workings, they are given a trapezoidal or rectangular sectional shape. The trapezoidal shape is used with timber lining and the presence of slight pressure from the surrounding rocks. The rectangular-vaulted form is used for monolithic concrete, sprayed concrete, anchor and combined (anchor with sprayed concrete) lining and in workings that do not have lining (for strong stable rocks).
There are cross-sectional areas in the clear, in the rough and in the penetration. The cross-sectional area in the clear is determined by the dimensions of the excavation to the support, minus the areas occupied by the ballast layer of the rail track and the ladder of the footpath. Rough sectional area is the projected area (in penetration). The actual cross-sectional area of ​​the excavation in the sinking is slightly larger than the cross-sectional area in the rough. When driving, it is necessary to observe that the cross-sectional area of ​​the mine workings corresponds to the existing "Standards for the excess of the sections of mining workings in the sinking in comparison with the sections in the rough during the performance of geological exploration". Depending on the hardness of the rocks, an increase in the sectional area in the rough by a factor of 1.04-1.12 is allowed. A large value of the coefficient corresponds to a cross-sectional area of ​​4 m2 in hard rocks.
The size of the cross-section in the clear depends on the purpose of the mine and is determined by the dimensions of the rolling stock and the number of rail tracks, the width of the conveyor, scraper or handling machine, taking into account the necessary clearances between these machines and the support, which are regulated by safety rules. The gap between the rolling stock and the support in long sections of the mine working with rail transport is not less than 200 mm with monolithic concrete, anchor and sprayed concrete support and not less than 250 mm with other types of support - flexible metal and wood. If the rolling of the trolleys along the development is carried out manually, then with all types of support this gap is 200 mm.

For horizontal exploration workings, two forms of cross-sections are established: trapezoidal (T), rectangular-vaulted with a box vault (PS).

Distinguish between the cross-sectional areas of horizontal workings in the clear, in the sinking and in the rough. The clear area (5 SV) is the area enclosed between the lining of the working and its soil, minus the cross-sectional area, which is occupied by the ballast layer poured on the soil of the working.

The area in the sinking (5 P |)) - the area of ​​production, which it is obtained in the process of carrying out before the erection of the support, the laying of the rail track and the device of the ballast layer, the laying of engineering communications (cables, air, water pipelines, etc.). Rough area (5 8H) - the area of ​​production, which is obtained in the calculation (projected area).

Since 5 VCh = 5 SV + 5 cr, then the calculation of the sectional area of ​​the working begins with the calculation in the light, where 5 cr is the section of the working occupied by the support; Кп „- the coefficient of the section busting (the coefficient of the excess section - CIS).

The dimensions of the cross-sectional area of ​​horizontal workings in the clear are determined based on the conditions for the placement of transport equipment and other devices, taking into account the necessary clearances, regulated by the Safety Rules.

In this case, it is necessary to consider the following possible cases of excavation and section calculation:

1. Development is carried out with fastening and the loading machine works in a fixed working. In this case, the calculation is carried out according to the largest dimensions of the rolling stock or loading machine.

2. Development is carried out with fastening, but the support lags behind the face by more than 3 m. In this case, the loader works in the unsecured part of the working.

When calculating the dimensions of the cross-sectional area for the largest dimensions of the rolling stock, it is necessary to make a verification calculation (Fig. 11):

t + B + n "> 2nd + 2*2+ T+ In with.+ NS; H p + th 3> Az +<* + and-

The decryption of the data is given below.

3. Development is carried out without fastening. Then size it up! cross sections calculated
are carried by the largest dimensions of tunneling equipment or mobile
composition.



The main dimensions of underground vehicles are standardized with the goal of typing the sections of workings, the structure of the support and tunneling equipment.

For trapezoidal workings, standard sections have been developed with the use of continuous lining, staggered lining, with only the roof tightening and with the roof and sides tightening.

Typical cross-sections of rectangular-vaulted workings are provided without support, with anchor, sprayed concrete and combined support

Rock pressure

Creation of safe conditions for the functioning of underground structures is one of the main tasks of ensuring the stability of mine workings. The technogenic impact of mining on the geological environment leads to its new state. (The geological environment here is understood as the real physical (geological) space within the earth's crust, which is characterized by a certain set of geological conditions - a set of certain properties and processes).

Quantitatively and qualitatively new force fields appear around the geological-geological object as a part of the geological environment, which appear at the boundary between a mine working and a rock mass, i.e. within the insignificant limits of the rock mass surrounding the mine.

The forces that arise in the massif surrounding the mine are called rock pressure. Rock pressure around the workings is associated with the redistribution of stresses during their conduction. It manifests itself as;

1) elastic or viscoelastic displacement of rocks without destruction;

2) collapse (local or regular) in weak, fractured and

fine-bedded rocks;

3) destruction and displacement of rocks (in particular, collapse) under the influence of ultimate stresses in the rock mass along the entire perimeter of the working section or in its individual sections;

4) extrusion of rocks into the working due to plastic flow, in particular from the side of the soil (swelling of rocks).

The following types of rock pressure are distinguished:

1. Vertical - acts vertically on the support, filling mass and is a consequence of the pressure of the mass of the overlying rocks.

1. Lateral - is a part of the vertical pressure and depends on the thickness of the rocks overlying the working or the developed layer, the engineering-geological characteristics of the rocks.

3. Dynamic - occurs at high speeds of application of loads: explosion, rock bump, sudden collapse of roof rocks, etc.

4. Primary - the pressure of rocks at the time of excavation.

5. Steady-state - the pressure of rocks after the excavation after some time and not changing for a long period of its functioning.

6. Unsteady - pressure that changes over time due to mining, rock creep and stress relaxation.

7. Static - the pressure of rocks, in which inertial forces are absent or very small.

The increasing complexity of the conditions in which the (underground construction) of mine workings is carried out (large depths of development, permafrost, high seismicity, neotectonic phenomena, the acceleration and increase in the volume of technogenic impact, etc.), and the level of development of science made it possible to create modern, more close to real methods for calculating rock pressure.

A new scientific direction arose - the mechanics of underground structures. This is a spider about the principles and methods of calculating underground structures for strength, rigidity and stability under static (rock pressure, groundwater pressure, temperature changes, etc.) and dynamic (blasting, earthquakes) effects. She develops methods for calculating support structures.

The mechanics of underground structures arose as a result of the development of rock mechanics - a science that studies the properties and patterns of change in the stress-strain state of rocks in the vicinity of a mine, as well as patterns of interaction of rocks with the support of mine workings to create expedient methods of rock pressure control. The mechanics of underground structures operates with mechanical models of the interaction of the support with the rock mass, taking into account the geological state of the rocks surrounding the mine, and the calculation schemes of the support.

The analysis of mechanical models and design schemes is carried out using the methods of the theory of elasticity, plasticity and creep, the theory of fracture, hydrodynamics, structural mechanics, strength of materials, theoretical mechanics.

The dimensions of the cross-section of horizontal mine workings in the clear depend on its purpose and are determined based on the dimensions of the rolling stock and the equipment located in the mine, ensuring the passage of the required amount of air, the gaps between the protruding parts of the rolling stock and the support provided for by the Safety Rules and the method of movement of people.

In our case, we design a horizontal vaulted excavation with roof bolting.

Rectangular-vaulted sections are used when driving workings without support or with the construction of lightweight support structures. The height of the vault in sections from 2 to 6.8 m 2 is?. working width.

The clear cross-sectional area is the area along the inner contour of the support installed in the working

Calculation of the section of the mine

Slitting width

b = b c + 2c = 0.95 + 2 0.3 = 1.55m

where b c - scraper width, m;

c is the gap between the scraper and the side of the mine, m.

In a mine of the type under consideration, people are allowed to walk only when the scraper installation is inoperative. Thus, the clearance height is assumed to be minimal, i.e. 1.8 m.

Arch height

Side cutting height (up to the heel of the arch):

1.8 - minimum production height according to PB

According to the calculated cross-sectional area in the light, the nearest larger of the standard cross-sections from table is taken. 2 (Tutorial "Conducting horizontal exploration workings and chambers" Authors V.I.

A typical cross-section of the production of substations is accepted - 2.7

The main dimensions of the cross-section of the working in the clear:

Working width, mm - b = 1550 mm

Working height to the heel of the arch, mm - h b = 1320 mm

Working height, mm - h = 1850 mm

The radius of the axial arc of the arch, mm - R = 1070 mm

The radius of the side arc of the arch, mm - r = 410 mm

Cross-sectional area of ​​openings, m 2 - S sv = 2.7 m 2.

For workings with roof bolting:

where is the height of the working on the side, taking into account the exit of the anchors along the roof into the working by the value d = 0.05 m.

Calculation of the strong dimensions of the lining, drawing up the fastening passport

Due to the small section of the mine, short service life, mining and geological conditions and the available materials, we use metal expansion bolting AR-1

All calculations of the strength of anchorage in the borehole of the roof bolting were made according to the formulas from the reference book "Theory and practice of using roof bolting" Author A.P. Shirokov. Moscow "Nedra" 1981

c - angle of friction of rocks, 30 degrees

D - spacer sleeve diameter, 32cm

h - height of the spacer sleeve, 30cm

y s is the ultimate compressive strength of the rock

b - half the angle of a symmetrical wedge, 2 degrees

p 1 - the angle of friction of steel on steel, 0.2 deg

The required length of the anchor L and in the roof and the height of the possible fallout of the working rocks is found from the expressions:

L a = b + L 2 + L 3 = 0.04 + 0.35 + 0.05 = 0.44m;

where L 2 - the value of the depth of the anchors beyond the contour of a possible rock fall (taken equal to 0.35 m); L 3 - the length of the anchor protruding beyond the mine contour, L k = 0.05 m; and n = half-span of working in tunneling, m; h is the height of the excavation in the sinking, m.

Coefficient characterizing the stability of the sides of the mine;

Coefficient characterizing the slope of the creep prism in the sides of the working (taken according to Table 12.1. Theory and practice of using bolting. Author A.P. Shirokov. Moscow "Nedra" 1981);

c b - angle of internal friction (resistance) of rocks in the sides of the mine; К к - coefficient taking into account the decrease in the strength of rocks in the roof of the mine (taken according to Table 13.1);

f to - the coefficient of rock hardness in the roof of the workings;

K comp is the coefficient of concentration of compressive stresses on the mine contour, the value of which is taken from table. 12.2;

d - the average specific gravity of rock strata overlying the mine to the surface, MN / m 3; Н - working depth from the surface, m;

K b - coefficient taking into account the decrease in the strength of rocks in the sides of the working, the value of which is taken according to Table 12.1;

f b - coefficient of rock hardness according to M.M. Protodyakonov in the sides of the mine.

We accept the length of the anchor in the roof L k = 0.5 m.

Due to the fact that w0, anchoring of the sides of the excavation is not performed.

Roof area supported by one anchor

where F to - the area of ​​the roof, supported by one anchor, m 2;

P k - the strength of the anchor in the hole drilled in the roof;

The safety factor, taking into account the uneven distribution of the load on the anchor and the possibility of surcharging from the side of the overlying layers, is taken equal to 4.5;

b - the angle of inclination of the working, degree 0 0

Distance between anchor in a row:

where L n is the step of installing the anchors along the width of the working, m;

L y - the distance between the rows of anchors, m, taken as 1.4 m

Number of anchors in a row

where L b = 1.33b = 1.331.55 = 2.06m - part of the working perimeter, which is subject to anchoring along the roof, m. Where b - the width of the working in the rough.

Accepts 2 anchors in a row.

Drawing up a fastening passport.

Clear cut width:

B = B + 2m = 950 + 3002 = 1550mm.

Cutting arch height

h about = b / 3 = 1550/3 = 520mm.

Rough cut height

h 2 = h + h o + t = 1320 + 520 + 50 = 1890mm.

Rough cut wall height

h 3 = h + t = 1320 + 50 = 1370mm.

Radius of the axial arc of the cutting arch

R = 0.692b = 0.6921550 × 1070mm.

Radius of the lateral arc of the cutting arch

r = 0.692b = 0.6921550? 410mm.

Clear cross-sectional area:

S sv = b (h + 0.26b) = 1.55 (1.32 + 0.261.55)? 2.7m 2

Cross-sectional perimeter of the cut in the light:

P = 2h + 1.33b = 21.32 + 1.331.55 = 4.7m.

Cross-sectional area of ​​the cut in the rough:

S high-frequency = b (h 3 + 0.26b) = 1.55 (1.37 + 0.261.55) = 2.75m 2.

Rough cut cross-sectional perimeter:

P = 2h + 1.33b = 21.37 + 1.331.55 = 4.8m

Distance between anchors in a row: b 1 = 1200mm.

Distance between rows of anchors: L = 1.4 m

Depth of holes for anchors: l = 500mm.

Diameter of holes for anchors: = 43mm.

The maximum lag of anchor support from the bottom of the face is taken to be 3 m.

Scheme for calculating the dimensions of the cross-section when using scraper equipment in the development of a rectangular-vaulted section shape.

 

It might be helpful to read: