SU1580014A1 - Method of guarding mine working - Google Patents

Abstract

The invention relates to the construction of underground structures and is intended for tunneling. The goal is to ensure the sustainability of the arch of the excavation (B) with a vertical axis of symmetry built in rocks with a lateral spread factor of less than 1/3. Before each approach in front, B 1 forms a zone of increased compressive stresses. For this, in the face on the vertical axis of symmetry B 1 along its longitudinal axis, a leading slit 4 is arranged by the amount of maximum fit. The lower end of the slit 4 is placed under the contour of the arch B 1 by the width of this end, and the height is determined for a specific geological situation from a mathematical expression. Then the slit 4 is sealed and the solution 6 expanding during hardening is placed in it. Due to the expansion of the solution 6 during hardening, a pressure is applied by a certain amount on the host rocks and forms a zone of pre-compressed rocks. Its size along the vertical axis of symmetry B 1 forms not less than the maximum height of the assumed tensile stress zone 2 arising in the arch during passage B 1. Lining is built in unstable rocks, and reinforcement is inserted into slot 4 before placing solution 6. After penetrating B 1, solution 6 with lining is monolithic. 1 hp f-ly, 3 ill. solution 6 with lining monolithic. 1 hp f-ly, 3

Description

The invention relates to the construction of underground structures, in particular (to methods of tunneling under the conditions of prevailing vertical pressure with the use of advanced fastening.

The aim of the invention is to ensure the stability of the arch of the excavation with the vertical axis of symmetry cooler in rocks with a lateral expansion factor less than 1/3.

FIG. 1 shows the production, longitudinal section; in fig. 2 - the same, cross section; in fig. 3 graphs of stress distribution in the roof of the mine.

When driving development 1 round or vaulted shape in the rocks with a coefficient of lateral expansion

Mf (1 + AK1) - (1-A) () cos20, (1)

where 6 and 6 „are respectively radial and tangential normal stresses, MP a-,

gibi-cylindrical coordinates (E is counted horizontally from the OX axis, OU is directed vertically, and the origin of coordinates is located in the center of the working); R is the radius of development, m. Tangential stresses

A zone of tensile stress 2 is formed in its roof, the level of which can be determined by the known dependencies:

(f + A (1 -) +

 one

+ O - L) (1 - 4 + 3p-) Jcos20i

g R

 6 (1 - L) cos26

- (1 + L) -VC1 + A) a - 12cos2 5d -L1 n (1 - L) gsoc2e

The indicated zone 2 has a maximum height of 1 tmix g - R at b 90 °, i.e. on the vertical axis of production symmetry 1. With this in mind, determine the maximum height of the proposed zone 2 tensile stresses:

6 (1 - D)

1 + A + Vl + 26A -23A4

fl, (4)

where B is the width of production for round

development (2R). The maximum width b of the front 01 01 of the lagging zone 2 of tensile stress 6 Q for the selected coordinate system:

 -Sov where value

l 11 + l

Q - 2agssozG TU

V0

 ЈН

R

(1 - L) (1 -)

25

„R

+.

(2)

The boundary of the danger zone 2 tensile stresses

(3)

Thus, the maximum dimensions of the proposed zone 2 of tensile normal stresses with their maximum values are: along the vertical Q of the potassium along the axis OY, and horizontally along the line Y of R.

After determining the size and location of the proposed 2 tensile normal stresses, it is necessary to carry out measures aimed at compensating these zones 2 before carrying out generation 1, and, consequently, penetrating the latter in more favorable conditions.

Q conditions The most rational is the preliminary directional redistribution of stresses in front of the bottom 3 in the roof of the mine 1, for which in an intact massif they form an area of increased compressive stresses, the absolute value of which is; comparable to the tensile stresses that will arise after the excavation of the mine 1. The zone is increased5

The compressive stresses in the array in front of them are formed by force acting on it through a pre-made cavity 4 with a pressure of a certain value. .

High pressure is advisable to create not by injection of solutions, which requires appropriate equipment and compliance with PB, but due to spontaneous expansion of the material placed in the advance cavity 4. In studying the patterns of stress state around cavities C of various configurations, it has been established that rational from the point of view of the technology of constructing a cavity, around which sufficient compressive stresses are formed when a pressure is created inside it, there is a gap 4.

At the same time, it is necessary that the height of the leading slit 4 should not be less than the height of the proposed zone 2 of tensile stresses that occur during the passage of generation 1. Since the tensile stresses reach their maximum values in the central part of the arch, the slit 4 must be located along vertical axis of symmetry generation 1 - axis OY.

The distribution of normal stresses around a linear slit located along the axis OY is given by:

(R

- 1) e (/ +

one)

(P +2 cos28 +1)

; (7)

() (1 + 2p + p4 + 4.p2cos29T 40 (P + 2p “cos2e +1) 1

W

where P is the pressure generated at the

finds cracks, MPa;.,

x +

Uh2 h-12/4.

1/2

(9)

1 - slot length, m

When going from the central part of the slit 4 to its ends, the level of compressive stresses decreases, but this decrease is slower than the decrease in absolute values of tensile stresses 2 in the same direction.

Thus, with the right choice of the location of the gap 4 and its

the dimensions of the tensile stresses in the direction of OY are compensated to the necessary degree if the value of pressure in slit 4 is selected as follows:

Р 6р - уН (ЗЛ - 1).

(YU)

At the ends of the slit 4, tensile stresses arise, therefore it is necessary to slit 4 along the vertical symmetry of the axis OY of the excavation so that its ends extend beyond the boundaries of the zone of tensile stresses 2 by the width of the end of the slit 4. Then the height of the slit C is determined

at 2

6 (1 -A)

1 + A + VI + 26 - 23A1

, (ii;

) 0 fj 20

-25 d 30

35

)

40

.

55

Thus, before each inlet in front of the bottom 3 of the excavation 1, a zone of increased compressive stresses is formed. To do this, in the bottom 3 on the vertical axis of symmetry of generation 1 along its longitudinal axis, a leading slit 4 is arranged. To create a leading slit 4, for example, such well-known methods as drilling in a series of secant wells, drilling fracturing or eroding the gaps between them, as well as cutting through the bar. The leading slit 4 is arranged for a maximum fit 5. In this case, the lower end of the leading slit 4 is placed under the contour of the arch of future production 1 by the width of its lower end (or borehole diameter, if it is created by drilling) and the height is determined for a specific mining and geological situation from the expression

(eleven). I

For convenience of work, it is advisable to build a niche (not shown) for placing equipment for arranging the slit 4 therein. The latter is sealed — in this case, in unstable rocks, a jumper (not shown) is erected for this purpose. After the slit 4 is arranged and sealed, for example, a solution 6, which expands during hardening, for example, expanding or self-hardening cement, is placed in it. Discharge pressure and composition of solution 6 select j

so that the pressure developed by them during hardening corresponds to the value of expression (10). Then, due to expansion of the solution 6, during hardening, they produce a force on the host rocks and form a zone of precompressed rocks, whose transverse size along the vertical axis of symmetry of the excavation forms not less than the maximum height of the intended zone 2 of tensile stresses that occur in the arch during penetration of the excavation 1 .

Under certain geological conditions, the ril impact does not exceed atmospheric pressure, i.e. solution 6, expanding to a finite size, should only fill the gap l and not exert pressure on its walls.

In unstable rocks, where, despite the redistribution of stresses, it is necessary to erect a permanent support in the leading gap 4, they make a stiffener. To this end, before injection of the expanding mortar 6, an armature (not shown) is inserted into it, and as the excavation mines after the erection, lining is connected with the latter into a single whole.

Solution 6, expanding in an enclosed space, significantly increases its strength as compared to freely expanding. In addition, I will act on the armature, it produces its prior stress.

After solidification of solution 6, directional redistribution of stresses in the vault and compensation of tensile stresses of zone 2 in front of slab 3, work is continued on penetration of output 1. The device in the pre-slot slit k) filled with hardening solution 6 in conjunction with HEP equalized redistribution of zheniye serves as the element of advancing fastening.

,

Claims (2)

1. A method of guarding mine workings, including a device for the advance cavity ahead of the bottom, placing in it an expanding solution during hardening, exerting a force effect on the host rocks during expansion and forming 5 Q stresses in them, the sealing of cavities, the excavation of excavation, characterized in that, in order to ensure the stability of the arch of the excavation with a vertical axis of symmetry constructed in rocks with a lateral dimension of less than 1/3, determine the dimensions of the supposed tensile stress zone, arising in the roof of the mine when it penetrates, and in the zone of higher stresses additionally form a zone of compressed rocks, the size of which along the vertical axis of symmetry of the mine takes no less than the height of the intended stretch zone boiling voltages with anticipatory cavity arrange a slit, which is performed on the vertical axis of symmetry generation, and have its lower end under the roof contour by the amount of the width of this end, and the height h is determined from the expression AT 6P-L)  P1-M A1 , 25 Q 35 40 50 55 where h is the height of the slit, m; B - width of production, m; And - lateral thrust coefficient; d. - the width of the lower end of the slit, m, while the force on the host rocks in order to compensate them for the proposed zone of tensile stresses is produced by pressure, which is determined from the expression Р 6р - - at N (3 A - D, where P is the pressure created by the expanding solution hardening, MPa; 6p ultimate strength rocks for stretching, MPa; Y is the volume weight of the host rocks, Mn / m H - the depth of the laying of production, m. 2. A method according to claim 1, characterized in that the lining is erected in unstable rocks, and the reinforcement is inserted into the leading slit before placing the solution expanding during the hardening of the solution; J v- vV HHH # J U jTT yy. .-r -frr - .T7: rtr g QN. .V- .. -l / Vv v -v --- Kv -: -:.;. .-. : - / ... “... V: .t.: -.:; -: - - ..Vr j -t c. ...- -. / L: ..- V. FIG. 1 3 tf 5 3C.fi