CN116220554A - Combined drilling method for filling steep multi-seam goaf - Google Patents

Abstract

The invention relates to the technical field of drilling treatment of a steep goaf, in particular to a combined drilling method for filling a steep multi-seam goaf, which comprises the following steps: s1: selecting proper drilling equipment according to the filling treatment requirements of the steeply inclined multi-seam goaf; s2: before drilling construction, preparing a drilling flushing fluid leakage emergency plan; s3: constructing a grouting curtain at the boundary through directional drilling along the coal seam inclination; s4: the earth surface is vertically drilled, and shallow goaf treatment is realized through the drilling grouting step; s5: directional drilling along the normal direction of the coal seam and finishing the treatment of the deep goaf through the drilling grouting step; s6: and (5) detecting and reinforcing the grouting treatment effect by nearly horizontally drilling along the trend of the coal seam. The combined drilling and pore-forming process can ensure safe and efficient pore-forming of grouting and drilling, and fully ensure grouting effect; especially for the steep multi-seam goaf, a plurality of gateway roadways with complex connection exist in the mine, and the combined drilling process is adopted, so that grouting filling quality is remarkably improved.

Description

Combined drilling method for filling steep multi-seam goaf

Technical Field

The invention relates to the technical field of drilling treatment of a steep goaf, in particular to a drilling construction method capable of realizing rapid, safe and efficient drilling of a steep broken coal seam goaf, and especially relates to a combined drilling method for filling of a steep multi-coal seam goaf.

Background

The coal seam with the inclination angle below 8 degrees is a nearly horizontal coal seam, the coal seam with the inclination angle between 8 degrees and 25 degrees is a gentle inclined coal seam, the coal seam with the inclination angle between 25 degrees and 45 degrees is an inclined coal seam, and the inclination angle above 45 degrees is a steep inclined coal seam. The technology of goaf drilling exploitation aiming at coal beds such as a near horizontal coal bed, a gently inclined coal bed and the like in the prior art is relatively mature, and a certain number of prior art schemes exist.

There are also some presently disclosed techniques for drilling in steeply dipping formations, such as: patent application CN201010152658.6 discloses a technique for drilling directional inclined holes in a steep earth formation. However, the method is mainly used for improving the process of directional inclined hole drilling aiming at the core drilling construction environment of the common steep formation, and is not used for breaking the special formation environment of the steep coal seam goaf which is used for mining coal and forms the goaf.

In the prior art, the filling and drilling technology for the special environment of the broken stratum of the steep coal seam goaf forming the goaf after coal mining still has relative defects, and the main reasons are that the special environment of the broken stratum of the steep coal seam goaf has the problems of large construction hidden trouble, complex geological environment, high construction difficulty and the like.

As is known, the goaf of the steep coal seam is usually a close-range multi-coal seam goaf at present. When the steep short-distance coal seam group is mined, when the lower-layer coal is mined, the water guide fracture is usually developed to the upper-layer coal, so that the goaf of the upper-layer coal seam and the goaf of the lower-layer coal are communicated during the mining, and the mining of the upper-layer coal is influenced; when the upper coal is mined firstly, unlike a near-horizontal coal bed, a bottom plate fracture zone of a goaf of the steeply inclined coal bed is likely to develop to the lower layer, so that the mining of the lower coal is affected.

The mining cracks of the steep coal measure stratum develop, the subsidence deformation of the earth surface is obvious, and the groove-shaped collapse is often generated; particularly in the outcrop area of the coal seam, the phenomenon of caving and collapsing usually occurs, and the mining of the steep close-range coal seam group is easy to form a large-range surface water area. The damage to the surface building structure is large, the grouting and subsidence reducing requirements of the coal mining subsidence area are also high, and the drilling layout form and the drilling construction process are obviously limited by a large-scale water accumulation area.

In addition, in the prior art, the traditional drilling method (namely, the traditional vertical drilling process) of the steep coal seam goaf is mainly adopted, whether national standard specification or engineering construction practice is adopted, the traditional vertical drilling process applied to the steep coal seam goaf is basically consistent with that of the near-horizontal coal seam goaf, and whether the arrangement mode of vertical grouting drilling is adopted, and the drilling structure and drilling process parameters are not obviously changed; the two-hole drilling structure adopts square grid or triangle uniformly distributed holes.

The construction process has the advantages of large engineering quantity, complex hole forming construction process of penetrating multiple layers of goafs, difficult control of drilling tracks, long hole forming period and low efficiency; and the single-hole grouting filling radiation area is small, the grouting efficiency is low, the conventional vertical drilling track is uncontrollable, the hole forming difficulty of penetrating through the stratum of the multi-coal seam goaf is high, and the holes cannot be distributed due to the fact that the large-range ponding on the ground surface is limited.

In addition, with the above vertical drilling process, grouting holes are uniformly arranged in a square lattice shape or a triangle shape, and the drilling process and method have the following problems:

(1) When the steep coal seam is mined, the included angle formed by the gravity action direction of the rock and the bedding plane direction of the rock is reduced due to the large inclination angle of the coal seam, so that the acting force of gravity along the bedding direction is greatly increased. This results in a range of characteristics that differ from those of mining a slow-sloping coal seam, such as the form of movement of the surrounding rock, roof fall, and deformation characteristics of the roadway. Especially, the special development form of the water-guiding fracture zone of the overburden stratum and the difference of the distribution characteristics of the residual gaps of the goaf lack of pertinence in the conventional drilling process and the drilling layout form, the grouting filling efficiency is low, and the possibility of hidden danger of grouting quality is high.

(2) The specificity of occurrence of steeply dipping coal seams is generally subject to strong geological fluctuations. The geological structure is complex and the occurrence of instability is unstable. Conventional vertical drilling is difficult in pore forming, drilling track control is difficult, and pore forming efficiency is low.

(3) The mining cracks of the steep coal measure stratum develop, the subsidence deformation of the earth surface is obvious, and the groove-shaped collapse is often generated; particularly in the outcrop area of the coal seam, the phenomenon of caving and collapsing usually occurs, and the mining of the steep close-range coal seam group is easy to form a large-range surface water area. The damage to the surface building structure is large, the grouting and subsidence reducing requirements of the coal mining subsidence area are also high, and the drilling layout form and the drilling construction process are obviously limited by a large-scale water accumulation area. Conventional vertical drilling processes cannot meet grouting treatment requirements of a steep coal seam goaf.

(4) At present, the mined goaf of the steep coal seam is mostly a close-range multi-coal seam goaf. Aiming at the goaf of the steep close coal seam group, the conventional vertical drilling process has difficult hole forming, low drilling speed, easy occurrence of drilling accidents and low grouting efficiency.

(5) The steeply inclined coal seam has the characteristics of mine exploitation, mining mode, roof management mode, mining area roadway arrangement and stope stoping technology, and the obvious difference between the working face of the goaf and the roadway arrangement mode enables the grouting drilling arrangement mode to be different. Conventional vertical drilling edges are arranged at certain intervals in a trend manner, so that grouting blind areas are easy to occur, and grouting quality hidden danger is generated. And conventional vertical drilling is difficult to accurately drill a mining area roadway due to limited drilling track precision, and grouting quality weak areas can be generated.

Therefore, the invention provides a method for realizing rapid, safe and efficient drilling construction for the steeply inclined multi-seam goaf, which can effectively solve various dilemmas and defects faced by the traditional vertical drilling grouting filling and better solve the problems in the prior art.

Disclosure of Invention

The invention aims to solve one of the technical problems, and adopts the following technical scheme: a combined drilling method for steeply dipping multiple seam goaf filling, comprising the steps of:

s1: selecting proper drilling equipment according to the requirements of the burial depth, the lithology of the overburden rock, the drilling type and the drilling structure of the goaf;

s2: before drilling construction, preparing a drilling flushing fluid leakage emergency plan;

s3: during construction, constructing a grouting curtain at the boundary of a treatment area through directional drilling along the trend of the coal seam (process a);

firstly, constructing curtain drilling along coal seam inclination at the treatment boundary of the goaf of the steeply inclined coal seam, penetrating through a plurality of horizontal goafs during construction when the goafs at different levels are conducted, and constructing at the treatment range boundary of the coal mining subsidence area by adopting a progressive sectional pore-forming technology during drilling.

Along the directional drilling of coal seam trend, the drilling adopts the progressive segmentation pore-forming technology, and a drilling runs through a plurality of horizontal goafs simultaneously, and the curtain construction efficiency is high.

S4: after the boundary construction grouting curtain is completed, constructing a ground surface vertical drilling (process b) and realizing shallow steep multi-seam goaf treatment in the treatment area through the drilling grouting step;

the vertical drilling (process b) of the ground surface is simple in drilling structure, few in ineffective grouting sections, high in hole forming efficiency and low in cost, and can well finish effective grouting of the goaf with shallow burial depth and outcrop area in the inner steeply inclined multi-coal seam goaf.

S5: while the earth surface vertical drilling (process b) is carried out, the construction is carried out along the coal seam normal directional drilling (process c) and the deep goaf treatment is finished through the drilling grouting step;

the drilling structure is multi-branch inclined directional drilling, and deep goaf treatment is completed along the coal seam normal directional drilling (process c) aiming at the goaf of the lower layer with large burial depth or the goaf without vertical drilling construction conditions caused by surface water accumulation. The problems of high difficulty in vertical drilling from the ground surface construction, penetration of a multi-layer goaf, formation crushing, high drilling accident rate and difficult hole forming in the traditional process are solved; and normal directional drilling is adopted in the specific area, the directional drilling is utilized to enter the goaf from a more complete stratum outside the working surface, so that the hole forming efficiency is improved, multi-branch directional drilling is utilized, the grouting efficiency of directional filling drilling is improved, and invalid grouting hole sections are reduced.

The earth surface vertical drilling (process b) and the directional drilling (process c) along the coal seam normal direction are synchronously constructed, so that simultaneous grouting of different mining horizontal goafs up and down can be realized, the treatment period is greatly shortened, and the treatment efficiency is improved.

S6: after the treatment of the surface vertical drilling (process b) and the directional drilling (process c) along the normal direction of the coal seam is finished, the grouting treatment effect is detected and reinforced by the construction of the near horizontal drilling (process d) along the trend of the coal seam.

Because the technical difficulty of long-distance near-horizontal drilling along goaf broken stratum is high, the near-horizontal drilling along coal seam trend (process d) is started after the grouting of the surface vertical drilling (process b) and the directional drilling along coal seam normal (process c) is completed.

The drilling structure in the near horizontal drilling along the coal seam trend (process d) is long-distance near horizontal drilling, and when the goaf working surface trend width is large, horizontal branch drilling is arranged along the main hole in a retreating mode.

The difference with the multi-branch directional drilling of the near-horizontal coal seam is that (namely, the effect is that): the branch drilling holes of the directional drilling holes along the trend of the steeply inclined coal seam are intensively distributed on one side of the main hole, the space positions are distributed in a staggered way up and down, and in order to improve the grouting effect, the side drilling points of the branch drilling holes gradually move upwards; and branch drilling side drilling points of the multi-branch directional drilling of the near-horizontal coal seam are distributed along two sides of the main hole in a staggered way, branch drilling tracks are distributed on two sides of the main hole, and the side drilling points can be in a forward type or a backward type.

The near horizontal drilling (process d) along the coal seam trend is constructed, the near horizontal section of the drilling is longer, the horizontal drilling is mainly performed in the goaf broken formation, the hole forming difficulty is high, the vertical drilling of the process b and the normal directional drilling of the process c are needed to perform pre-grouting, the formation is filled and reinforced to a certain extent, then the construction is performed, the process d mainly drills Duan Dou in the goaf, the grouting filling efficiency is high, and the grouting quality weak areas existing after grouting by adopting the processes a, b and c can be supplemented and detected, so that the grouting quality detection drilling is also used, each horizontal directional drilling along the goaf trend controls one line, the line forms a surface, compared with the point type detection efficiency of the vertical drilling, the non-blind area of grouting filling is fully ensured.

In any of the above schemes, preferably, the drilling grouting step is as follows:

drilling construction is carried out along the design track of the current stratum, when the total leakage of the circulating liquid occurs, top leakage drilling is carried out for 10-20m, drill rod pressurized water is utilized to flush the drill hole for 30min, and a drilling tool is lifted;

installing an orifice grouting device, starting to perform pressure grouting on the cement fly ash composite slurry, and recording grouting flow and pressure change conditions during grouting; stopping grouting after the grouting pressure reaches the design standard;

After standing for 12-24 hours, the orifice grouting device is disassembled, a drilling tool is put into the orifice grouting device to start flushing the drilling hole, and the drilling tool is lifted out after residual slurry in the drilling hole is flushed;

installing an orifice grouting device, and performing pressure grouting to cement slurry so as to strengthen grouting on the wall of a drilling hole; when the grouting pressure reaches the final hole standard, the grouting of the section is finished, and the grouting is performed for 48-72 hours;

after the waiting for the solidification is finished, drilling a drilling tool, detecting the strength of cement paste, continuously drilling along a design track after the strength reaches the design requirement, and drilling 10-20m in a top leakage way according to the complete condition of the hole wall until the hole is formed;

after the hole is formed by drilling, installing a hole opening grouting device, injecting cement fly ash composite slurry under pressure, ending grouting when the grouting flow and grouting pressure reach the design final hole standard, and adjusting grouting parameters when the drilling grouting amount exceeds 1.5 times of the design grouting amount and still does not reach the design final hole standard, and after grouting is completed, unloading the hole opening device and sealing the hole to the hole opening.

In any of the above schemes, preferably, in the construction of directional drilling (process a) along the coal seam, when the boundary coal seam of the treatment area has a plurality of working face goafs at different levels, a progressive sectional hole forming method is adopted until the boundary goafs of the treatment area are entered;

In the near horizontal drilling holes (process d) along the coal seam trend, when the width of the working surface trend is larger, and only one drilling hole is arranged along the coal seam trend and cannot fully cover the same working surface mining space, the directional drilling main holes are arranged on the upper part of the working surface, after grouting of the main holes is completed, branch drilling holes are arranged below the main holes, and each branch drilling hole sequentially advances from top to bottom to drill into a hole.

In addition, considering that the trend width of the working face of the domestic steep coal seam is generally smaller, 1-2 branch drilling holes are arranged on the same working face.

In any of the above schemes, preferably, when the same coal seam has a plurality of working face goafs at different mining levels, the working face goafs enter the coal seam along the normal direction, drilling and grouting are started from the goafs at the lower part, and after the working face goafs are completed, the working face goafs are constructed upwards step by step.

In any of the above schemes, preferably, when the goaf of the steeply inclined coal seam in a certain mining area needs to be partially filled, constructing an isolation curtain by adopting low-fluidity slurry at the boundary of a grouting filling area, constructing a grouting boundary curtain, and avoiding the slurry from diffusing to the goaf outside the filling area; the boundaries are the upper and lower boundaries of the current treatment area along the vertical direction and the boundaries of the two sides along the trend.

In any of the above schemes, preferably, the drilling method for constructing a curtain includes the following steps:

according to the estimated value of the grouting slurry diffusion range, reasonably setting the distance between the curtain drilling hole and the boundary of the designed filling area, wherein the curtain drilling track is not too close to the filling boundary;

curtain drilling is carried out, aggregate is injected, and the drilling aperture is more than or equal to 110mm;

the directional drilling track of the designed grouting layer section is preferably in a linear type along the trend or trend of the coal seam, the included angle of the broken line type is not preferably smaller than 120 degrees, and the curvature radius of the curve type drilling track is not preferably smaller than 50m; so as to avoid abnormal end of grouting caused by blocking of drilling holes by aggregate slurry;

in order to ensure the drilling track precision, the layer contact angle is not suitable to be less than 30 degrees;

when the boundary of the area is filled, the grouting slurry is changed into high-concentration thick slurry, a certain proportion of fine aggregate is doped, the particle size of the aggregate in the near-horizontal drilling hole is less than or equal to 3mm, and the doping proportion is 15-50%, so that the fluidity of the slurry is obviously reduced;

if necessary, adding an accelerator accounting for 2 percent of the weight of the cement, and reducing the setting time of the slurry;

in the curtain grouting process, grouting is performed in a low-pressure and current-limiting mode, grouting pressure and grouting unit flow are strictly controlled, and intermittent grouting is performed when single grouting amount is large.

Unlike near horizontal coal seams, the caving and breaking zones of steeply dipping coal seams typically develop into a fourth line, even when the coal seam outcrop area causes drainage, collapse, and in such cases, there is a significant technical difficulty in designing the construction of the upper boundary curtain of the filling area. And because the dip angle of the coal seam is extremely large, conventional grouting slurry continuously flows downwards by means of dead weight, and is difficult to stay at the bottom of a designed filling area to be piled up to a certain height, so that the construction difficulty of a boundary curtain at the bottom is also high. In order to ensure that the boundary curtain wall is successfully constructed, the boundary curtain drilling method is adopted.

In any of the above schemes, it is preferable to drill holes in a descending type section when holes Duan Ju with holes collapse, stuck or seriously lost flushing fluid cannot be drilled normally in the drilling process and holes are difficult to be formed once, so as to ensure safe hole forming;

after the single section is formed, grouting is started by washing the hole with water, grouting is ended, the grouting is performed for 36-72h, and then the next section drilling construction is started.

In any of the above schemes, it is preferable to increase the grouting pressure to 3-4MPa in the grouting ending stage, and the concentration of the selected slurry is not too thick, so as to improve the reinforcing effect of the grouting slurry on the broken hole wall, effectively prevent hole collapse accidents and ensure the reinforcing effect of the drilling segmented hole wall stratum.

In any of the above schemes, preferably, when the drilling is grouting in sections, in the end stage of grouting in each section, the cement-based composite slurry is adjusted to be pure cement slurry added with accelerator, so that the slurry setting speed is increased, the interval waiting setting time of the next section drilling of the drilling is reduced, and the drilling hole forming efficiency is improved.

In any of the above schemes, preferably, when the soft broken stratum or the horizontal section is drilled, a flexible drilling tool combination is adopted, four low drilling parameters are selected, the drilling mode of short tripping and small displacement gradually reaching normal displacement is adopted, and the technology of well track refinement control is combined, so that the soft coal seam clear water drilling is realized, and the instability and collapse of the well wall are prevented; preventing the horizontal well wall of the soft coal seam/stratum from collapsing.

Compared with the prior art, the invention has the following beneficial effects:

1. the combined drilling and pore-forming process can ensure safe and efficient pore-forming of grouting and drilling and fully ensure grouting effect; particularly for a steep multi-seam goaf, a plurality of gateway roadways with complex connection generally exist in a mine, and a combined drilling process is adopted to effectively eliminate grouting blind areas caused by various roadways and remarkably improve grouting filling quality.

2. Because of the intrinsic difference between the occurrence states of the goaf of the steeply-inclined broken coal seam and the occurrence states of the goaf of the nearly-horizontal coal seam, the method is used for drilling grouting of the goaf of the steeply-inclined coal seam (belonging to the mined broken stratum), the difficulty in carrying out drilling construction on the broken stratum is high, and the process of directional drilling for goaf governance in the prior art is not applicable to the goaf treatment of the steeply-inclined broken coal seam and cannot realize safe and efficient grouting filling; for grouting in the steep multi-seam goaf, the main grouting target interval of the drilling is positioned in the water guide fracture zone of the top plate of the goaf to the goaf, the drilling process has the defects of crossing the broken stratum, seriously leaking drilling flushing fluid and the like, the drilling needs to penetrate the extremely broken stratum in a long distance in the steep seam, and the drilling construction can be rapidly, safely and efficiently carried out through the process.

3. In the method, the drilling interval is increased at the middle lower part of the goaf, the drilling interval is properly reduced at the middle upper part of the goaf, or multi-branch directional drilling holes are arranged along the seam in the seam, so that the drilling accidents of crushing the stratum at the top and bottom plates of the steeply inclined seam can be effectively reduced, and besides the falling and moving of the roof strata, the probability of rolling, slipping and other problems of the bottom plate strata can be effectively reduced under certain conditions.

4. According to the method, when the stratum outside the working face of the coal bed is required to enter the goaf, multiple rows of drilling holes are arranged along the trend of the coal bed, drilling tracks are designed to be vertical to the coal-line stratum to drill, the drilling tracks can be measured while drilling by utilizing directional drilling, and can be adjusted at any time, so that the drilling holes enter the water guide fracture zone along the normal direction of the coal-line stratum, the drilling deflection probability is remarkably reduced, the drilling deviation correcting times are reduced, and the drilling holes are guaranteed to be quickly drilled according to the designed tracks. The problem that the inclination angle of the stratum in the goaf of the steeply inclined broken coal seam is very large, the traditional drilling arrangement mode is utilized, the drilling track always forms a certain included angle with the stratum, the included angle passing through different strata changes, the drilling track is difficult to control, track deflection is easy to occur when the drilling passes through different stratum interfaces, and particularly when the difference of the hardness of the upper layer and the lower layer is obvious, the drilling track is guaranteed to be relatively large along the design track construction difficulty is solved.

5. The directional grouting drilling holes are arranged along the coal seam, the directional drilling track is controlled with high precision, and the deviation is dynamically corrected in the drilling process, so that the hidden danger of grouting quality caused by the deviation of the drilling holes can be avoided, and the problem that the projection area of the steep coal seam goaf along the horizontal direction is smaller due to the specificity of occurrence of the steep coal seam goaf can be solved. The treatment area is a long and narrow shape area with small projection distance along the trend and large projection length along the trend, grouting holes are arranged in the long and narrow shape treatment area, the distance between the holes along the trend is small, the control precision of the conventional vertical drilling track is low, and the deflection of the holes can cause the problems that two drilling target points are close to or even coincide, and the grouting filling effect is affected.

6. The multi-step and multi-drilling method is adopted in the process method to realize comprehensive drilling effect, multi-branch directional drilling holes are arranged along the trend and the trend of the coal seam, so that full coverage grouting filling of the goaf can be ensured, the grouting efficiency is high, and grouting blind areas are effectively avoided. And conventional vertical drilling edges are arranged at certain intervals in a trend, so that grouting blind areas are easy to occur, and grouting quality hidden danger is generated. And conventional vertical drilling is difficult to accurately drill a mining area roadway due to limited drilling track precision, and grouting weak areas can be generated.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or features are generally identified by like reference numerals throughout the drawings. In the drawings, the elements or components are not necessarily drawn to scale.

FIG. 1 is a cross-sectional view of a conventional steeply dipping coal seam.

FIG. 2 is a schematic view of a conventional steeply inclined goaf.

Fig. 3 is a schematic diagram of a layout of a borehole in a plane of the process b and the process d in a downward viewing angle.

Fig. 4 is a schematic diagram of a layout of a borehole in a plane of the process a, the process b, the process c, and the process d in a downward viewing angle.

Fig. 5 is a schematic layout diagram of the front view of the process b and the process d according to the present invention.

Fig. 6 is a schematic layout distribution diagram of each process drilling in the cross-section state of fig. 1.

Wherein F in fig. 1 represents the ground.

Detailed Description

Embodiments of the technical scheme of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present invention, and thus are merely examples, and are not intended to limit the scope of the present invention. The specific structure of the invention is shown in figures 1-6.

The steep coal seam goaf is different from the traditional near-horizontal coal seam goaf in three points:

(1) The occurrence states of the steep coal seam goaf and the near-horizontal coal seam goaf are different, the main difference is that the inclination angles of the coal seam are different, the steep coal seam is mostly an unstable complex coal seam, and engineering geological conditions are complex.

In general, steeply dipping coal seams experience strong geological formation movements. The geological structure is complex and the occurrence of instability is unstable.

The goaf of the near-horizontal coal seam in the same mining area is generally in the same elevation range, and the plane projection area is large. The working face of the steeply inclined coal seam is generally arranged along a certain elevation in a certain mining area, and isolation coal pillars are reserved between different elevations, so that the working face of the steeply inclined coal seam is generally shorter in trend, longer in trend and long in plane projection in an elongated strip shape.

Because the inclination angle of the coal bed is larger, the development form of the three zones of the overlying strata of the coal bed is obviously different from that of a near-horizontal coal bed, the bottom plate of the goaf of the steeply inclined coal bed is generally seriously damaged, grouting treatment is needed, and the development ranges of the water guide fracture zones of the overlying strata of the coal bed and the goaf are different.

(2) The steeply inclined coal seam has large inclination angle, the working face of the steeply inclined coal seam has poor general labor conditions, and the coal seam is small in thickness. One panel typically has a height of 80-200 a m a double wing panel running length of 400-600 a m a. The mining area is also generally divided into sections along the inclination, but the section inclination length is generally smaller, and is only 15-20m smaller and 50-60 m larger depending on the coal mining method selected. The width of the coal pillar between the sections is typically 3-5 m. This also results in a smaller projected extent of the goaf along the inclined plane, and if the grouting borehole spacing is still in accordance with the near horizontal seam goaf, the actual distance of the two grouting boreholes in the goaf is large, with a higher grouting quality risk. ( Examples: for a steep coal seam goaf with a burial depth of 500 and an inclination of 75 degrees, the grouting drilling holes are offset by more than 30 meters along the goaf bottom plate every time the drilling holes are deviated by 1 degree. According to the specification, the grouting hole spacing is 10-30m. It can be seen that the borehole offset has been greater than the borehole spacing. )

(3) The steep coal seam is due to geological structure factor, usually has the multilayer goaf, and has the link up between each layer of goaf more, and is more broken and broken hole section is longer in the stratum than nearly horizontal coal seam goaf, and drilling pore-forming difficulty.

The void distribution of the near-horizontal coal seam goaf generally accords with the O-shaped ring theory, the middle area is small, and the peripheral area close to the coal pillar is large. The steep coal seam goaf is small in the void ratio of the lower part of the bottom plate, large in the void ratio of the upper part of the bottom plate, and usually contains large holes, so that the phenomenon of drill falling is easy to cause.

Because the surface deformation of the steeply inclined coal seam is strong, the technical requirement on directional drilling is higher, and the method comprises the steps of controlling the track accuracy of drilling, reducing the distance between branch drilling holes, improving the cement content of grouting slurry in the outcrop area of the coal seam, and the like.

The subsidence deformation rule of the ground surface is inconsistent, the maximum subsidence deformation position of the near-horizontal coal seam goaf is usually in the middle of the goaf, and the ground surface subsidence of the fully mined goaf is in a basin shape. For a steep coal seam goaf, the position of the ground surface subsidence deformation most distance is not in the middle of the goaf, but is located in the range of the position of the middle upper part of the working surface, which is deviated to the outcrop position of the coal seam.

The pressure of the overburden layer acting on the roof of the coal seam changes along with the increase of the inclination angle of the coal seam, the roof of the steeply inclined coal seam goaf bears the vertical component force exerted by the overburden layer and is smaller than the gentle inclination, the component force acting along the inclination is larger, the development forms of the water guide fracture zones caused by mining are different due to different stress states of the roof strata, the forms of the water guide fracture zones of the nearly horizontal coal seam are generally saddle-shaped or arched, the upper arch angle and the lower arch angle of the roof stratum damage area of the steeply inclined coal seam goaf show the characteristics of being large and small up and down, the funnel shape of roof damage gradually becomes smaller along with the increase of the angle, and the lower arch angle gradually becomes sharp.

In addition, the main treatment target area of the coal mining subsidence area is the goaf water guiding fracture zone, and the development forms of the goaf water guiding fracture zone of the steeply inclined coal seam are different, so that the traditional process cannot be effectively applied to the effective treatment of the goaf of the steeply inclined coal seam.

For this purpose, the embodiment designs a combined drilling method for filling a steep multi-seam goaf, which comprises the following steps:

s1: selecting proper drilling equipment according to the requirements of the burial depth, the lithology of the overburden rock, the drilling type and the drilling structure of the goaf;

s2: before drilling construction, preparing a drilling flushing fluid leakage emergency plan;

s3: during construction, constructing a grouting curtain at the boundary of a treatment area through directional drilling along the trend of the coal seam (process a);

firstly, constructing curtain drilling along coal seam inclination at the treatment boundary of the goaf of the steeply inclined coal seam, penetrating through a plurality of horizontal goafs during construction when the upper goaf and the lower goaf are conducted, and constructing at the treatment range boundary of the coal mining subsidence area by adopting an advancing type segmented pore-forming technology during drilling.

Along the directional drilling of coal seam trend, the drilling adopts the progressive segmentation pore-forming technology, and a drilling runs through a plurality of horizontal goafs simultaneously, and the curtain construction efficiency is high.

S4: after the boundary construction grouting curtain is completed, constructing a ground surface vertical drilling (process b) and realizing shallow steep multi-seam goaf treatment in the treatment area through the drilling grouting step;

the vertical drilling (process b) of the ground surface is simple in drilling structure, few in ineffective grouting sections, high in hole forming efficiency and low in cost, and can well finish effective grouting of the goaf with shallow burial depth and outcrop area in the inner steeply inclined multi-coal seam goaf.

The vertical drilling adopts a three-hole structure (wherein, three-hole structure parameters are that the drilling diameter (casing diameter) is 311.1mm/273, 244.5mm/177.8 and 152mm/110, or one-hole is 311.1mm/244.5, two-hole is 215.9/168.3mm and three-hole is 149.2/114.3 mm), and the vertical drilling is convenient to process when the drilling jam and the burying accident occur in the broken stratum.

After the pouring of the orifice sleeve is completed, a pressure test is carried out after the casting is completed for 48 hours, the test pressure is generally 3.5-4.5MPa, the pressure test time is not less than half an hour, the pressure loss is not more than 0.5MPa, and the next grouting can be carried out after the test result is qualified. The step can ensure the subsequent sectional grouting effect and avoid grouting slurry flowing into the surface soil layer from between the sleeve and the hole wall or from the ground surface. When a large-area ponding area is met, multi-branch inclined directional drilling holes are required to be distributed outside the ponding area, so that the problem that vertical drilling cannot be directly adopted is solved.

S5: while the earth surface vertical drilling (process b) is carried out, the construction is carried out along the coal seam normal directional drilling (process c) and the deep goaf treatment is finished through the drilling grouting step;

the drilling structure is multi-branch inclined directional drilling, and deep goaf treatment is completed along the coal seam normal directional drilling (process c) aiming at a lower layer coal seam goaf with large burial depth or an earth surface water area without drilling construction conditions. The problems of high difficulty in vertical drilling from the ground surface construction, penetration of a multi-layer goaf, formation crushing, high drilling accident rate and difficult hole forming in the traditional process are solved; and normal directional drilling is adopted in the specific area, the directional drilling is utilized to enter the goaf from a more complete stratum outside the working surface of the mining area, so that the hole forming efficiency is improved, multi-branch directional drilling is utilized, the grouting efficiency of directional filling drilling is improved, and invalid grouting hole sections are reduced.

When the upper three belts and the lower three belts vertically penetrate through the goaf in construction in the direction perpendicular to the coal seam, the upper three belts and the lower three belts of the top plate and the bottom plate of the steeply inclined coal seam are ensured to be effectively filled with grouting, and the grouting treatment quality is improved;

the wall protection sleeve is arranged in a bedrock section which is just below the orifice sleeve, the wall protection sleeve is preferably an equal-aperture expansion sleeve, the sleeve is expanded to the aperture size after being arranged in a preset layer section, and the blocking of a complex layer section can be realized under the condition that the drilling order is not increased, so that the problems of hole collapse during drilling and subsequent repeated hole sweeping during grouting are avoided in a particularly crushed stratum; the wall protection sleeve should pass the broken stratum, pour the solid pipe of grout between wall protection sleeve and the pore wall.

The wall-protecting sleeve is not suitable to penetrate into the goaf grouting layer section, and the end of the sleeve is connected with the flower pipe when entering into the goaf water-guiding fracture zone.

The vertical drilling (process b) and the directional drilling (process c) along the normal direction of the coal seam are synchronously constructed, so that simultaneous grouting of different horizontal goafs can be realized, the treatment period is greatly shortened, and the treatment efficiency is improved.

S6: after the treatment of the surface vertical drilling (process b) and the directional drilling (process c) along the normal direction of the coal seam is finished, the grouting treatment effect is detected and reinforced by the construction of the near horizontal drilling (process d) along the trend of the coal seam.

When the directional drilling holes are arranged along the trend of the coal seam, each branch hole is arranged on the same coal seam, and construction is carried out from one side to the other side;

the boreholes tend to reduce the borehole plane spacing, ensuring that the borehole is no more than 30m from the target point spacing across the goaf.

The inclination angle of the coal seam is larger than 45 degrees along the inclination of the coal seam, and the calculation shows that the plane distance of the vertical grouting drilling target point is not larger than 21m. When vertical coal seam directional drilling or bedding directional drilling is adopted, the distance between two adjacent branch drilling target points is not more than 30m.

During construction, the drill holes tend to penetrate through the goafs of the working surfaces at different mining levels along the same mining coal seam at one time, and downward grouting is performed along the mining coal seam, so that grouting efficiency of the drill holes is improved.

In the process a, when a curtain is required to be built at the bottom boundary of a treatment area, near-horizontal drilling holes along the trend can be distributed in a goaf at the bottom boundary, the curtain is built along the trend treatment boundary, and a curtain boundary is formed, namely, the bottom boundary of the treatment area is formed by adopting low-fluidity grouting slurry;

the curtain formed by adopting the grouting slurry with low fluidity can effectively prevent the overflow loss of the slurry, and avoid excessive waste of the slurry while greatly improving the grouting efficiency.

For the steeply inclined multi-seam goaf, the projection is smaller in the horizontal direction; however, for a borehole with a large burial depth, such as 500m burial depth, 1 ° offset, 8.7m offset horizontally, if 8.7m offset horizontally, it is likely to deviate from the steeply inclined goaf, especially the partial goaf of the isolated working face, thereby wasting the borehole and delaying the construction period, as defined herein: the vertical grouting drilling deflection distance is not greater than the thickness of the coal seam.

In addition, the directional drilling main holes sequentially penetrate through the plurality of coal seam goafs with different mining levels in the vertical direction in the steeply inclined multi-coal seam goaf, the inclined bedding branch holes are respectively arranged along the plurality of coal seam inclined directions with different mining levels, and one multi-branch directional hole group can synchronously take into account grouting filling of the plurality of coal seam goafs with different mining levels so as to further improve grouting filling efficiency and construction efficiency.

Because the technical difficulty of long-distance near-horizontal drilling along goaf broken stratum is high, the near-horizontal drilling along coal seam trend (process d) is started after the grouting of the surface vertical drilling (process b) and the directional drilling along coal seam normal (process c) is completed.

The drilling structure in the near horizontal drilling along the coal seam trend (process d) is long-distance near horizontal drilling, and when the goaf working surface trend width is large, horizontal branch drilling is arranged along the main hole in a retreating mode.

The difference with the multi-branch directional drilling of the near-horizontal coal seam is that (namely, the effect is that): the space positions of the branch drilling holes of the directional drilling holes along the trend of the steeply inclined coal seam are distributed in a vertically staggered way, and the side drilling points of the branch drilling holes gradually move upwards to improve the grouting effect; and branch drilling side drilling points of the multi-branch directional drilling of the near-horizontal coal seam are distributed along two sides of the main hole in a staggered way, branch drilling tracks are distributed on two sides of the main hole, and the side drilling points can be in a forward type or a backward type.

The near horizontal drilling (process d) along the coal seam trend is constructed, the near horizontal section of the drilling is longer, the horizontal drilling is mainly performed in the broken stratum of the goaf, the hole forming difficulty is high, the stratum needs to be pre-grouted through the vertical drilling of the process b and the normal directional drilling of the process c, the stratum is constructed after being filled and reinforced to a certain extent, the process d mainly drills Duan Dou in the goaf, the grouting filling efficiency is high, the grouting quality weak areas existing after grouting by adopting the processes a, b and c can be supplemented and grouted, therefore, the near horizontal section of the drilling is also used as grouting quality detection drilling, each horizontal directional drilling along the goaf is used for controlling one line, the line forms a surface, compared with the point type detection efficiency of the vertical drilling, the point type detection efficiency of the line is high, and the grouting filling non-blind area is fully ensured.

When directional drilling is arranged along the trend of the coal seam, the branch holes are not at the same height, and the branch holes are preferably constructed in sequence from top to bottom, so that after grouting of the upper branch holes is finished, stratum of the adjacent branch holes below is reinforced, the hole forming efficiency of the subsequent branch holes is gradually improved, the distance between the subsequent branch holes can be adjusted in real time according to the grouting quantity of the previous branch holes, drilling construction cost is reduced, and the treatment period is shortened. When grouting drilling holes are arranged along a coal seam, multi-branch inclined directional drilling holes are arranged so as to improve the construction efficiency of drilling grouting.

In addition, grouting is carried out in a large range in a goaf at a certain mining level of the steeply inclined coal seam, so that the drilling grouting efficiency is improved; the grouting filling construction of the working face goaf on the same mining level can be completed by adopting fewer drilling holes; the goaf adopts a progressive sectional drilling process, and the drilling and grouting processes are crossed in construction.

In any of the above schemes, preferably, the drilling grouting step is as follows:

drilling construction is carried out along the design track of the current stratum, when the total leakage of the circulating liquid occurs, top leakage drilling is carried out for 10-20m, drill rod pressurized water is utilized to flush the drill hole for 30min, and a drilling tool is lifted;

Installing an orifice grouting device, starting to perform pressure grouting on the cement fly ash composite slurry, and recording grouting flow and pressure change conditions during grouting; stopping grouting after the grouting pressure reaches the design standard;

after standing for 12-24 hours, the orifice grouting device is disassembled, a drilling tool is put into the orifice grouting device to start flushing the drilling hole, and the drilling tool is lifted out after residual slurry in the drilling hole is flushed;

installing an orifice grouting device, and performing pressure grouting to cement slurry so as to strengthen grouting on the wall of a drilling hole; when the grouting pressure reaches the final hole standard, the grouting of the section is finished, and the grouting is performed for 48-72 hours;

after the waiting for the solidification is finished, drilling a drilling tool, detecting the strength of cement paste, continuously drilling along a design track after the strength reaches the design requirement, and drilling 10-20m in a top leakage way according to the complete condition of the hole wall until the hole is formed;

after the hole is formed by drilling, installing a hole opening grouting device, injecting cement fly ash composite slurry under pressure, ending grouting when the grouting flow and grouting pressure reach the design final hole standard, and adjusting grouting parameters when the drilling grouting amount exceeds 1.5 times of the design grouting amount and still does not reach the design final hole standard, and after grouting is completed, unloading the hole opening device and sealing the hole to the hole opening.

In any of the above schemes, preferably, in the construction of directional drilling (process a) along the coal seam, when the boundary coal seam of the treatment area has a plurality of working face goafs at different levels, a progressive sectional hole forming method is adopted until the boundary goafs of the treatment area are entered;

in the near horizontal drilling holes (process d) along the coal seam trend, when the width of the working surface trend is larger, and only one drilling hole is arranged along the coal seam trend and cannot fully cover the same working surface mining space, the directional drilling main holes are arranged on the upper part of the working surface, after grouting of the main holes is completed, branch drilling holes are arranged below the main holes, and each branch drilling hole sequentially advances from top to bottom to drill into a hole.

In addition, considering that the trend width of the working face of the domestic steep coal seam is generally smaller, 1-2 branch drilling holes are arranged on the same working face.

In any of the above schemes, preferably, when the same coal seam has a plurality of working face goafs at different mining levels, a main hole is firstly constructed on the lowest working face, and after grouting of the main hole is completed, 1-2 branch holes are respectively distributed in each working face goaf from bottom to top in sequence; each branch hole sequentially and backwardly drills holes from bottom to top along the track of the main hole.

In any of the above schemes, preferably, when the goaf of the steeply inclined coal seam in a certain mining area needs to be partially filled, a low-fluidity slurry is adopted to construct an isolation curtain at the boundary of the grouting filling area, and a grouting boundary curtain is constructed to avoid the diffusion of the slurry to the goaf outside the filling area.

In any of the above schemes, preferably, the drilling method for constructing a curtain includes the following steps:

according to the estimated value of the grouting slurry diffusion range, reasonably setting the distance between the curtain drilling hole and the boundary of the designed filling area, wherein the curtain drilling track is not too close to the filling boundary;

curtain drilling is carried out, aggregate is injected, and the drilling aperture is more than or equal to 110mm;

designing a drilling track of a grouting layer section to be approximately horizontal or inclined downwards along a coal seam, wherein the inclination angle is less than or equal to 30 degrees, so as to avoid abnormal grouting ending caused by blocking of drilling by aggregate slurry;

when the boundary of the treatment area is filled, grouting slurry is changed into thick slurry, a certain proportion of fine aggregate is doped, the particle size of the aggregate in the near-horizontal drilling hole is less than or equal to 3mm, and the doping proportion is 15-50%, so that the fluidity of the slurry is obviously reduced;

if necessary, adding an accelerator accounting for 2 percent of the weight of the cement, and reducing the setting time of the slurry;

in the curtain grouting process, grouting is performed in a low-pressure and current-limiting mode, grouting pressure and grouting unit flow are strictly controlled, and intermittent grouting is performed when single grouting amount is large.

Unlike near horizontal coal seams, the caving and breaking zones of steeply dipping coal seams typically develop into the fourth line, even when the coal seam outcrop area causes drainage, collapse, and in this case, there is a significant technical difficulty in designing the construction of the boundary curtains of the filling area. And because the dip angle of the coal seam is extremely large, conventional grouting slurry continuously flows downwards by means of dead weight, and is difficult to stay at the bottom of a designed filling area to be piled up to a certain height, so that the construction difficulty of a boundary curtain at the bottom is also high. In order to ensure that the boundary curtain wall is successfully constructed, the boundary curtain drilling method is adopted.

In any of the above schemes, it is preferable to drill holes in a descending type section when holes Duan Ju with holes collapse, stuck or seriously lost flushing fluid cannot be drilled normally in the drilling process and holes are difficult to be formed once, so as to ensure safe hole forming;

after the single section is formed, grouting is started by washing the hole with water, grouting is ended, the grouting is performed for 36-72h, and then the next section drilling construction is started.

The specific sectional length is comprehensively determined according to the stratum breaking degree, the drilling equipment capacity and the grouting process; the common sectional length is about 10-50m, and when the stratum is seriously crushed, the one-time sectional drilling length is properly shortened.

The process steps of sectional pore-forming grouting are as follows: sectional drilling, cleaning drilling, grouting, waiting for solidification, sectional drilling, hole cleaning, grouting again, and finally goaf grouting until the designed hole depth is reached.

In any of the above schemes, it is preferable to increase the grouting pressure to 3-4MPa in the grouting ending stage, and the concentration of the selected slurry is not too thick, so as to improve the reinforcing effect of the grouting slurry on the broken hole wall, effectively prevent hole collapse accidents and ensure the reinforcing effect of the drilling segmented hole wall stratum.

In any of the above schemes, preferably, when the drilling is grouting in sections, in the end stage of grouting in each section, the cement-based composite slurry is adjusted to be pure cement slurry added with accelerator, so that the slurry setting speed is increased, the interval waiting setting time of the next section drilling of the drilling is reduced, and the drilling hole forming efficiency is improved.

In any of the above schemes, preferably, when the soft broken stratum or the horizontal section is drilled, a flexible drilling tool combination is adopted, four low drilling parameters are selected, the drilling mode of short tripping and small displacement gradually reaching normal displacement is adopted, and the technology of well track refinement control is combined, so that the soft coal seam clear water drilling is realized, and the instability and collapse of the well wall are prevented; preventing the horizontal well wall of the soft coal seam/stratum from collapsing.

The drilling flushing fluid is prepared to prevent collapse and leakage, so that normal drilling is ensured, and drilling efficiency is improved.

The multiple processes adopted in the invention are independent from the drilling angle, and can be applicable to different processes in different areas and different drilling construction stages aiming at the steep multi-seam goaf. Filling grouting in a goaf, namely arranging curtain drilling holes at the boundary of a defined treatment area, wherein the curtain grouting prevents excessive slurry loss; directional drilling along the coal seam trend is used as curtain grouting drilling; after curtain grouting is completed, filling grouting is started to the inside of the treatment area; in the treatment area, firstly, shallow vertical drilling is constructed, then normal directional drilling is constructed, and deep goaf grouting is performed in a targeted mode. And finally, when the injectability of the drilling holes is obviously reduced, the construction is performed along the trend directional drilling holes, and the grouting quality is detected, leakage is detected and the defects are repaired through a pressurized water experiment and grouting.

The combined drilling and pore-forming process can ensure safe and efficient pore-forming of grouting and drilling and fully ensure grouting effect; particularly for a steep multi-seam goaf, a plurality of gateway roadways with complex connection generally exist in a mine, and a combined drilling process is adopted to effectively eliminate grouting blind areas caused by various roadways and remarkably improve grouting filling quality.

Because of the intrinsic difference between the occurrence states of the steeply-inclined broken multi-seam goaf and the near-horizontal seam goaf, the method is used for drilling grouting of the steeply-inclined seam goaf (belonging to the mined broken stratum), the difficulty of carrying out drilling construction on the stratum is high, and the process of directional drilling for goaf governance in the prior art is not applicable to the treatment of the steeply-inclined broken seam goaf and cannot realize safe and efficient grouting filling; for grouting in the steep multi-seam goaf, the main grouting target interval of the drilling is positioned in the water guide fracture zone of the top plate of the goaf to the goaf, the drilling process has the unfavorable conditions of crossing the broken stratum, seriously leaking drilling flushing fluid and the like, the steep seam needs to penetrate the extremely broken stratum for a long distance, and the drilling construction can be realized rapidly, safely and efficiently through the process method.

In the method, the drilling interval is increased at the middle lower part of the goaf, the drilling interval is properly reduced at the middle upper part of the goaf, or multi-branch directional drilling holes are arranged along the seam layer, so that the drilling accidents of crushing the stratum on the top and bottom plates of the steeply inclined seam can be effectively reduced, and besides the falling and moving of the roof stratum, the probability of rolling, slipping and other problems of the bottom plate stratum can be effectively reduced under certain conditions; when the coal seam is required to enter the goaf from the stratum outside the mining working face, multiple rows of drilling holes are arranged along the normal direction of the coal seam, the drilling hole track is designed to be perpendicular to the coal seam stratum for drilling, the drilling hole track can be adjusted at any time by utilizing directional drilling measurement while drilling, so that the drilling holes can enter the water guide fracture zone along the normal direction of the coal seam stratum, the drilling hole deflection probability is obviously reduced, the drilling hole deviation correcting times are reduced, and the drilling holes can be rapidly formed according to the designed track. The problem that the inclination angle of the stratum in the goaf of the steeply inclined broken coal seam is very large, the traditional drilling arrangement mode is utilized, the drilling track always forms a certain included angle with the stratum, the included angle passing through different strata changes, the drilling track is difficult to control, track deflection easily occurs when the drilling passes through different stratum interfaces, and particularly when the difference of the hardness of the upper layer and the lower layer is obvious, the drilling track is guaranteed to be relatively large along the design track construction difficulty is solved. The directional grouting drilling holes are arranged along the coal seam, the directional drilling holes are controlled with high precision, and the deviation is dynamically corrected in the drilling process, so that the hidden danger of grouting quality caused by the deviation of the drilling holes can be avoided, and the problem that the projection area of the steep coal seam goaf along the horizontal direction is smaller due to the specificity of occurrence of the steep coal seam goaf can be solved. The treatment area is a long and narrow shape area with small projection distance along the trend and large projection length along the trend, grouting holes are arranged in the long and narrow shape treatment area, the distance between the holes along the trend is small, the control precision of the conventional vertical drilling track is low, and the deflection of the holes can cause the problems that two drilling target points are close to or even coincide, and the grouting filling effect is affected.

The multi-step and multi-drilling method is adopted in the process method to realize comprehensive drilling effect, multi-branch directional drilling holes are respectively arranged along the trend, the trend and the normal direction of the coal seam, so that full coverage grouting filling of a goaf can be ensured, the grouting efficiency is high, and grouting blind areas are effectively avoided. And conventional vertical drilling edges are arranged at certain intervals in a trend, so that grouting blind areas are easy to occur, and grouting quality hidden danger is generated. And conventional vertical drilling is difficult to accurately drill a mining area roadway due to limited drilling track precision, and grouting weak areas can be generated.

The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions; any alternative modifications or variations to the embodiments of the present invention will fall within the scope of the present invention for those skilled in the art.

The present invention is not described in detail in the present application, and is well known to those skilled in the art.

Claims (8)

1. A combined drilling method for filling a steep multi-seam goaf is characterized by comprising the following steps of: the method comprises the following steps:

s1: selecting proper drilling equipment according to the requirements of the burial depth, the lithology of the overburden rock, the drilling type and the drilling structure of the goaf;

s2: before drilling construction, preparing a drilling flushing fluid leakage emergency plan;

s3: during construction, constructing a grouting curtain at the boundary of a treatment area by directional drilling along the trend of the coal seam;

s4: after the boundary construction grouting curtain is completed, constructing the ground surface to vertically drill holes and realizing shallow steep multi-coal-seam goaf treatment in the treatment area through the drilling grouting step;

s5: while the earth surface vertical drilling is carried out, the construction is carried out along the directional drilling of the coal seam normal direction, and the deep goaf treatment is completed through the drilling grouting step;

s6: and after the surface vertical drilling and directional drilling treatment along the normal direction of the coal bed are completed, the grouting treatment effect is detected and reinforced by the construction along the coal bed trend near horizontal drilling.

2. A combined drilling method for steeply dipping multiple seam goaf filling as claimed in claim 1 wherein: in the directional drilling construction along the coal seam trend, when the boundary coal seam of the treatment area has a plurality of working face goafs at different levels, a forward type sectional hole forming method is adopted until the boundary goafs of the treatment area are entered;

When the width of the trend of the working face is larger and only one drilling hole is arranged along the trend of the coal seam, and the drilling hole cannot fully cover the same working face mining space, the directional drilling main hole is arranged on the upper portion of the working face, after grouting of the main hole is completed, branch drilling holes are arranged below the main hole, and each branch drilling hole sequentially advances from top to bottom to drill into a hole.

3. A combined drilling method for steeply dipping multiple seam goaf filling as claimed in claim 2 wherein: when the same coal seam has a plurality of working face goafs at different levels, the working face goafs enter the deep goafs along the normal direction of the coal seam, drilling and grouting are started from the goafs at the lower part, and after the working face goafs are completed, the working face goafs are constructed upwards step by step.

4. A combined drilling method for steeply dipping multiple seam goaf filling as claimed in claim 3 wherein: when a goaf of a steep coal seam in a certain mining area needs to be partially filled, constructing a separation curtain by adopting low-fluidity slurry at the boundary of a grouting filling area, constructing a grouting boundary curtain, and avoiding the diffusion of the slurry to the goaf outside a treatment area; the boundaries refer to the upper and lower boundaries in the vertical direction of the current treatment area.

5. A combined drilling method for steeply dipping multiple seam goaf filling as claimed in claim 4 wherein: the drilling method for constructing the curtain comprises the following steps:

According to the estimated value of the grouting slurry diffusion range, reasonably setting the distance between the curtain drilling hole and the boundary of the designed filling area, wherein the curtain drilling track is not too close to the filling boundary;

curtain drilling is carried out, aggregate is injected, and the drilling aperture is more than or equal to 110mm;

the directional drilling track of the designed grouting layer section is preferably in a linear type along the trend or trend of the coal seam, the included angle of the broken line type is not preferably smaller than 120 degrees, and the curvature radius of the curve type drilling track is not preferably smaller than 50m; so as to avoid abnormal end of grouting caused by blocking of drilling holes by aggregate slurry;

in order to ensure the drilling track precision, the layer contact angle is not suitable to be less than 30 degrees;

when the boundary of the area is filled, the grouting slurry is changed into high-concentration thick slurry, a certain proportion of fine aggregate is doped, the particle size of the aggregate in the near-horizontal drilling hole is less than or equal to 3mm, and the doping proportion is 15-50%, so that the fluidity of the slurry is obviously reduced;

if necessary, adding an accelerator accounting for 2 percent of the weight of the cement, and reducing the setting time of the slurry;

in the curtain grouting process, grouting is performed in a low-pressure and current-limiting mode, grouting pressure and grouting unit flow are strictly controlled, and intermittent grouting is performed when single grouting amount is large.

6. A combined drilling method for steeply dipping multiple seam goaf filling as claimed in claim 5 wherein: when a hole Duan Ju with hole collapse, drilling sticking or severe leakage of flushing fluid cannot be drilled normally in the drilling process and hole forming is difficult to realize once, downward sectional drilling is adopted to ensure safe hole forming;

After the single section is formed, grouting is started by washing the hole with water, grouting is ended, the grouting is performed for 36-72h, and then the next section drilling construction is started.

7. A combined drilling method for steeply dipping multiple seam goaf filling as claimed in claim 6 wherein: and in the grouting ending stage, the grouting pressure is increased to 3-4MPa, the concentration of the selected slurry is not too thick, and the mass concentration is controlled below 70%, so that the reinforcing effect of the grouting slurry on broken hole walls is improved, hole collapse accidents are effectively prevented, and the reinforcing effect of the hole wall stratum of the drill hole section is ensured.

8. A combined drilling method for steeply dipping multiple seam goaf filling as claimed in claim 7 wherein: when the drilling is grouting in sections, in the end stage of grouting in each section, cement-based composite slurry is adjusted to be pure cement slurry added with accelerator, so that the slurry coagulation speed is increased, the interval waiting time of next section drilling of the drilling is shortened, and the drilling hole forming efficiency is improved.

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