SU1027399A1 - Method of freezing rock - Google Patents

Abstract

THE METHOD FOR FREEZING BREEDS, including drilling freezing wells around the wellbore, installing B the wells of the freezing columns and supplying the coolant to the columns, differs in Perffro, which means, in order to improve the quality of freezing by preventing times. freezing columns, drilling wells from the depth of inelastic deformations of the rocks is carried out with a deviation from the vertical to the outside, and the radius of the circumference of the location of the wells in depth is chosen depending on the external load on the ice fence and the long-term strength of the frozen rocks in accordance with the ratio 1 / + 0- C gdegs. - radius of the location of the freezing wells, m; radius of the barrel in penetration, m; PH is the magnitude of the horizontal pressure on the ice fence MPa; 7 limit of long-term strength of frozen rocks, MPa.

Description

The invention relates to the construction of mines using the method of artificial freezing of rocks and can be used mainly in the construction of vertical shafts to great depths (over 300 m).

There is a method of freezing rocks, including drilling, freezing drilling, their wells and supplying coolant 1 to them.

The disadvantage of the known method is that, due to the small distance from the freezing wells to the trunk contour, a penetration of 0, 0 m is deformed, when the trunks penetrate, together with the surrounding rocks, into the trunk. As a result, the column tubes are broken at the threaded connections. The brine from the columns (calcium chloride solution) defrosts the fence around the blade, and water with sand fills the barrel.

There is also known a method of freezing rocks at great depths, including drilling freezing wells around the wellbore, installing wells in column pipes and supplying coolant to columns 2.

The disadvantage of this method is the appearance of a massive rupture of the columns of the inner row.

The purpose of the invention is to increase the quality of freezing by preventing the freezing columns from breaking.

The goal is achieved by the fact that, according to the method of freezing rocks, including drilling freezing wells around the wellbore, installing freezing columns in wells and supplying coolant to the columns, drilling wells from the depth of inelastic deformations of the rocks deviates from the vertical outwards the location of the wells in depth is chosen depending on the external load on the ice fence and the long-term strength of the frozen rocks in accordance with the ratio

l i + 06} f

 . -.Hb.,

where is the radius of the location of the freezing wells, m; radius of the barrel in penetration, m; p is the magnitude of the horizontal pressure on the ice fence, MPa;

d - Limit of long-term strength of frozen rocks, MPa. FIG. Figure 1 shows the change in the gradient L of the PH of the horizontal pressure on the ice panel fence in the loose stratum of rocks from the depth of the layer of chalk, marl, and clay; in fig. 2 is a diagram of the location of the freezing wells behind the zone.

overvoltage with deviation of wells in depth to the outer side; in fig. 3 is the dependence of the stress concentration factor Kg (K, j, where d is the greatest normal stress in the rock mass around the wellbore, MPa; P is the horizontal pressure at a predetermined depth in the untouched rock mass in the rock mass beyond the contour of the shaft in the penetration from the generalized radius R / RB); where R is the current o radius deep into the array from the contour of the trunk, RB is the radius of the trunk in the penetration.

The method is carried out as follows.

Freezing wells 1 are drilled beyond zone 2 of increased stresses and intense deformations of the ice fence 3. Moreover, as the depth increases (horizontal pressure on the ice fence), the freezing wells move away from the center of the trunk and underestimate position 4 in the plan. using known means (not shown), wells install freezing columns consisting of freezing and supply pipes (not shown) to which coolant is supplied (aqueous solution

5 calcium chloride) from the brine network of the freezing station.

The graph (Fig. 3) obtained from experimental data makes it possible to estimate the radius Rj of the zone of increased stresses for different radii Rj in the borehole penetration. With

0 R, 7-R, the stresses in the array are aligned and correspond to the value of the initial load P "on the fence, as. Therefore, if columns 1 are located in zone 5, then the voltage in the columns when the barrel penetrates will be minimal (the same as before the start of penetration). In this case, the removal of columns 1 beyond zone 2 prevents column breaks during the penetration and attachment of the trunk. It should be noted that under the action

As the rock pressure increases over the depth Pn, the radius R of the influence of the increased stresses increases. Therefore, the radius of the circle Rg of the location of the wells increases in depth and the bottom of the well at the final freezing depth takes

5 position 4.

In the proposed method, the ratio of the horizontal load P to the ice fence and the long-term strength of 6. frozen rocks of the fence can be taken as the determining criteria for estimating the radius R of the location of the wells 1. At the same time, the radius of the well location circle is selected in accordance with the ratio

1 + oh, used | 1,

about/

Kyb

where RC is the radius of the location of the freezing wells, m; radius of the barrel in penetration, m; the magnitude of the horizontal pressure on the ice wall fence, MPa; 6- limit of long-term strength of frozen rocks, MPa. The physical essence of the formula (1) is that the freezing wells are located at such a distance from the contour 6 of the wellbore that the stresses arising in the ice fence 3 at the locations of the boreholes 1 do not exceed the long-term strength of the frozen breeds of the fence. In this case, the freezing columns 1 do not fall into the zone of intense deformations 2 and ensure their safe operation during the penetration and fastening of the trunk. The results obtained according to formula (1) are in good agreement with the experimental data, i.e. the well location radius R falls into zone 5, which is located behind the elevated stress zone with radius Rj. In this connection, formula (1) can be used to select the safe radius of location of freezing wells around barrels constructed at great depths (more than 300 m). Dependence (1) is obtained from the following assumptions. Provided that the main normal stresses arising in the ice-breeding enclosure 1; 1 (LPO) do not exceed the ultimate strength of frozen rocks, the necessary thickness of the LPO is determined by the known dependence "VS" According to numerous field and experimental works, it is established that the period of formation of LPO fencing thickness in the inner direction, 6E, where E is the bearing thickness of LPO. 0.6 is the coefficient taking into account the dynamics of LPO growth in the internal direction, which indicates that due to the smaller heat influx (cooling of rocks in the trunk section), the increase in the enclosure of the internal zone is greater than in the external direction from the freezing columns 1. By the end of the freezing process, the thickness of the fence in the inner direction from the columns E5 is 0.6E, and in the outer direction - Ej, 0.4E. After substituting the expression for formula (2) for the fence thickness E, obtained from relationship (3), we obtain D v 0.6 -Mb; Dividing by term into R the left and right parts of expression (4) after simple transformations, we get .. t Expression (5) differs from expression (1) only by the signs between the left and right parts, i.e., in formula (1) t mark (greater or equal), meaning that the ratio of the radius of the circle of the location of the freezing wells to the radius of the barrel in the penetration must be at least a dimensionless quantity, standing on the right side of expression (1). In this case, the condition expresses the limitation of the radius of the column location on the side of deformation zone 2. Thus, the ratio (H) in dimensionless form reflects the new condition Limiting the radius of the column around the trunk depending on the criterion for evaluating the strength and deformability of the growth of LPO in the process of freezing rocks. An example of a specific implementation of the proposed method is considered in comparison with the method of freezing rocks to a depth of 620 m, which is currently used for driving the shafts of the Yakovlevsky mine KMA. For the conditions of the Zkovlevskoye field KM.4, the gradient of horizontal pressure on the ice barrier reaches a maximum value at a depth of 300 m. In this connection, starting from this depth, creep deformations develop most intensively in the ice fence. According to field observations, column breaks are mainly confined to contacts of unstable clays and rocks that are hardy in frozen state (sand, sandstone, limestone, etc.): Therefore, it is most appropriate to select wells for an unstable clay . The table shows the recommended values of the radii of the circumference of the location of the freezing wells, starting from a depth of 310 m, for the conditions of penetration of shafts at the Yakovlevskoye KMA deposit .. V

310

3.5 471 5.9 it96 6.1

9.1 9.7 9.8

As follows from the table, when the radius of the wellbore in the penetration of 5.15 m (at the site of installation of the flexibility nodes), the radius of the circumference of the wells in the depth interval of more than 300-496 m varies from 9.1 to 9.8 m, and the distance from the trunk contour to the columns will be 3.95–4.65 m in this case, as experience has shown in driving the shafts to great depths, the freezing columns do not fall into zone 2 of increased stresses and rock deformations, but are in zone 5 and work in safe conditions

The proposed method will prevent the breaks of the freezing pipe columns and accidents with flooding trunks. Besides.

the removal of columns from the contour of the trunk in the penetration will allow not to freeze the bottom of the trunk, which will increase the average penetration rates for the conditions of the Yakovlevskoye field by more than 2.4 times.

As the experience of drilling shafts 2 5 and 3 of the Yakovlev mine showed, the internal row of freezing columns practically did not work in the depth interval of 390-620 m. Due to this, the implementation of the proposed method: when building other shafts of the Yakovlev mine, it will also allow each barrel to reduce the total number of freezing wells, and consequently, to reduce the time and cost of drilling wells and installing columns.

Claims (1)

METHOD FOR FREEZING BREEDS, including drilling freezing wells around the trunk, installing freezing columns in wells and supplying coolant to the columns, characterized in that, in order to improve the quality of freezing by preventing breaks in the freezing columns, drilling wells from the depth of inelastic deformation of the rocks carried out with a deviation from the vertical to the outside, and the radius of the circumference of the location of the wells in depth is chosen depending on the external load on the ice fence and long awns frozen rocks in accordance with the relationship + 0,6gde Vs.- radius location circumferentially freeze wells, m; shaft radius in penetration, m; P _n · * the value of horizontal pressure on the ice fence MPa; 8 _? - ultimate strength of frozen rocks, MPa.