CN113389549B - Method for relieving stope mine pressure based on key layer reconstruction principle - Google Patents

Method for relieving stope mine pressure based on key layer reconstruction principle Download PDF

Info

Publication number
CN113389549B
CN113389549B CN202110830519.2A CN202110830519A CN113389549B CN 113389549 B CN113389549 B CN 113389549B CN 202110830519 A CN202110830519 A CN 202110830519A CN 113389549 B CN113389549 B CN 113389549B
Authority
CN
China
Prior art keywords
grouting
key layer
thickness
rock stratum
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202110830519.2A
Other languages
Chinese (zh)
Other versions
CN113389549A (en
Inventor
张广超
陶广哲
李友
左昊
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shandong University of Science and Technology
Original Assignee
Shandong University of Science and Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shandong University of Science and Technology filed Critical Shandong University of Science and Technology
Priority to CN202110830519.2A priority Critical patent/CN113389549B/en
Publication of CN113389549A publication Critical patent/CN113389549A/en
Priority to PCT/CN2022/101150 priority patent/WO2023000920A1/en
Application granted granted Critical
Publication of CN113389549B publication Critical patent/CN113389549B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21C—MINING OR QUARRYING
    • E21C41/00—Methods of underground or surface mining; Layouts therefor
    • E21C41/16—Methods of underground mining; Layouts therefor
    • E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04—Lining with building materials
    • E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations

Landscapes

  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Data Mining & Analysis (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Mathematical Physics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Structural Engineering (AREA)
  • Architecture (AREA)
  • Mathematical Analysis (AREA)
  • General Engineering & Computer Science (AREA)
  • Software Systems (AREA)
  • Civil Engineering (AREA)
  • Databases & Information Systems (AREA)
  • Pure & Applied Mathematics (AREA)
  • Mathematical Optimization (AREA)
  • Computational Mathematics (AREA)
  • Algebra (AREA)
  • Remote Sensing (AREA)
  • Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)

Abstract

The invention discloses a method for retarding stope mine pressure based on a key layer reconstruction principle. Firstly, determining the geometric dimension of a reconstructed key layer through theoretical calculation, wherein the geometric dimension comprises four parameters of inclined length, strike length, thickness and distance from a mining coal layer, and the thickness and lithology difference of the coal layer are fully considered; the quantitative cross-feed relation between the strength and the thickness of the key layer is established, a determination method for the strength and the thickness of the key layer is provided from the perspective of ensuring that the key layer does not slip and lose stability, and the quantitative design of the key layer reconstruction scheme is realized. Secondly, determining a key layer reconstruction site scheme, providing a cross stepping bottom inverse grouting scheme, designing parameters such as drilling hole arrangement, drilling hole diameter changing, grouting materials, grouting time and the like, and having reasonable design and strong operability; and finally, determining a key layer reconstruction construction process comprising grouting time, working procedures, labor organization and the like.

Description

Method for relieving stope mine pressure based on key layer reconstruction principle
Technical Field
The invention relates to the field of mine pressure and rock stratum control, in particular to a method for retarding stope mine pressure based on a key stratum reconstruction principle.
Background
Coal mining by well is the activity of coal mining and transportation in a stratum with a certain depth below the surface of the earth, and a layered rock stratum of dozens of meters or even nearly kilometers is covered on a coal seam. The lithology, thickness, strength, chemical composition, etc. of the layered rock stratum all show great differences. According to mining subject mine pressure and rock stratum control theory, rock stratum distribution characteristics and breaking rules thereof are important reasons influencing coal mining safety, and the following two conditions exist:
(1) when one to a plurality of hard rock layers with large thickness and high strength exist in the rock layer at the upper part of the coal seam, the hard rock layers are broken regularly along with the continuous mining of the coal seam, and a stable beam type or arch type balance structure is formed above the coal seam, so that the overlying strata pressure is prevented from being completely acted on a stope support, the support is important for preventing the stope support from pressing a frame and preventing the end face coal rock mass from leaking, and the rock layer which plays an active role in controlling the stope surrounding rock is called a key layer. Further, the instability form of the key layer is divided into sliding instability and rotation deformation instability according to the thickness and strength difference of the key layer, wherein the sliding instability is not beneficial to surrounding rock control of the stope.
(2) When the coal seam does not have a hard rock stratum which can be used as a key layer, if part of the coal seam in the northwest ningdong mining area of China is only covered by a sand soil layer of 50-150 m or the coal seam in mining areas such as the northwest great wilderness area and the north Anhui is covered by a weak rock stratum and a scouring deposit layer of hundreds of meters, the sand soil layer, the weak rock stratum or the scouring deposit layer have the characteristics of low strength and poor integrity and cannot play a role of the key layer. Under the geological conditions, in the process of coal seam mining, the weight of the upper rock stratum is completely or mostly applied to the stope support, so that the pressure of the stope support is increased and even is pressed, and the coal rock mass on the end face falls in a large range and other strong mine pressure phenomena directly influence the safety production and the economic benefit of a mine. For surrounding rock control under the stratum conditions, measures such as increasing the working resistance of a hydraulic support, improving the activity of a strut, grouting surrounding rock in a stope and the like are mainly adopted.
In terms of the existing research results, the instability form (slipping or rotation) of the key layer depends on the inherent conditions of the stratum such as the thickness, strength and geometric relationship of the key layer, and for the mine pressure influence on the stope caused by different instability forms of the key layer, measures such as increasing the support resistance, adjusting the hydraulic pressure state, reinforcing the surrounding rock at the end face and the like are mainly adopted in the stope at present. Considering the occurrence process of the instability motion of the key layer → the mine pressure appearing in the stope → the control measure adopted in the stope, it is known that the instability motion of the key layer is the root cause of the disaster accident, and the existing stope control measure is adopted after the mine pressure appearing caused by the motion of the key layer, and belongs to a hysteresis and passive measure. At present, reports of influencing the breaking and instability form of the key layer and improving the mine pressure of a stope by reconstructing the strength and the size of the key layer do not exist, and the reports belong to an advanced and active control measure.
Disclosure of Invention
The invention provides a method for relieving mine pressure of a stope by reconstructing a key layer, aiming at solving the problem of frequent mining pressure accidents of the stope under the condition of no key layer stratum and aiming at the stratum condition that the key layer cannot be formed on the upper part of a coal seam. Firstly, determining the geometric dimension of a reconstructed key layer through theoretical calculation, wherein the geometric dimension comprises four parameters of inclined length, strike length, thickness and distance from a mining coal bed; secondly, determining a key layer reconstruction site scheme, including a drilling arrangement scheme and parameters, grouting materials, grouting pressure and the like; and finally, determining a key layer reconstruction construction process comprising grouting time, working procedures, labor organization and the like.
A method for retarding stope mine pressure based on a key layer reconstruction principle comprises the following steps:
first step of on-site investigation and laboratory experiment
The lithology of the coal seam roof and the overlying strata, the thickness M of the coal seam, the thickness sigma h of the weak strata, the size of a working face, the fracture angle beta of the strata, the rotation angle theta of the strata, the fracture length a of a reconstructed key layer, the grouting loss coefficient lambda, the slurry filling rate epsilon, the slurry maturing rate M and the grouting amount c per hour are investigated on site; laboratory determination of compressive strength sigma of coal seam roof rock stratumcCoefficient of crushing expansion kiDensity rho, porosity eta, and influence coefficient delta of diameter change of a grouting pipeline;
second step, determining the spatial position and thickness of the reconstructed key layer
Step 2.1) determining the spatial position of a reconstructed key layer
Step 2.1.1) determining the height H of the reconstructed key layer from the mining coal seam
Based on the principle that the coal mining space can be filled due to the fact that the rock mass collapses and is subjected to crushing and expansion deformation after the coal seam is mined, determining the height H of the reconstructed key layer distance mining coal seam, wherein the expression is as follows:
Figure BDA0003175369320000021
in the formula, H is the height between the reconstructed key layer and the coal bed; delta is an influence coefficient, and the stability of a reconstructed key layer can be ensured when the delta is more than or equal to 90 percent; m is the thickness of the mined coal bed; k is a radical ofpThe composite crushing expansion coefficient of the caving rock mass is expressed as follows:
Figure BDA0003175369320000022
in the formula, k1、k2………kiThe crushing expansion coefficient of the 1 st and 2 … … i-th rock layers above the coal bed;
step 2.1.2) determining the dimensions of the reconstructed critical layer
Considering the mining influence range after coal seam mining, determining the trend length l and the trend length w of the reconstructed key layer, wherein the expression is as follows:
Figure BDA0003175369320000031
w＝w'+20 (4)
wherein l' is the working face inclination length; w' is the working face trend length; h is the height between the reconstructed key layer and the coal seam; beta is the fracture angle of the rock stratum;
step 2.2) determining the thickness of the reconstructed critical layer
According to the forming conditions of the key layer, simultaneously avoiding the key layer from slipping and destabilizing, and determining the thickness of the reconstructed key layer, wherein the expression is as follows:
Figure BDA0003175369320000032
in the formula, h is the thickness of a reconstructed key layer; h is1Is the thickness of the loading layer; sigmacIn order to reproduce the compressive strength of the key layer; i is the critical block fracture degree; theta is a rock stratum rotation angle; rho is the density of the reconstructed key layer; g is the acceleration of gravity, wherein the expression of i is:
Figure BDA0003175369320000033
in the formula, h is the thickness of the reconstruction key layer; a is the breaking length of the reconstructed key layer; thickness h of the loading layer1The expression is:
h1＝∑h-∑hm-∑hl (7)
in the formula, sigma h is the total thickness of the weak rock stratum; sigma hmThe height of the collapse zone of the weak rock stratum; sigma hlIs soft and weakA formation fracture zone height;
third step key layer reconstruction grouting reinforcement design scheme
Step 3.1) arranging grouting pipelines
Step 3.1.1) adopts a cross stepping bottom inverse grouting scheme to carry out pipeline arrangement: the staggered arrangement grouting work stations in the working face air return roadway and the transportation roadway are arranged, the staggered distance is 4-6 m, the interval between the grouting work stations in the same roadway is 8-11 m, and two adjacent grouting work stations in the two roadways are a group.
And 3.1.2) additionally arranging an inclined drilling hole from the roadway to the top plate, wherein the included angle phi between the inclined drilling hole and the top plate is 40-60 degrees, the vertical height of the drilling hole is (H + H), and the length of the pipeline is (H + H)/sin phi.
Step 3.1.3) dividing a grouting pipeline into two parts for better grouting reinforcement effect, wherein a casing is arranged in a slant drilling hole of a weak rock stratum section to prevent slurry from diffusing to an irrelevant rock stratum section, and the diameter of the drilling hole is 80-100 mm;
and 3.1.4) grouting and reinforcing the inclined drilling hole of the rock stratum section to be 50-70 mm in diameter, arranging a horizontal pipeline along the working face by using a directional drill, wherein the length is l/4, and the horizontal and vertical distance d is more than or equal to 3m and less than or equal to 5 m.
Step 3.2) determining grouting material and grouting amount
Selecting different grouting materials and proportions according to the fracture rate of the reconstructed key stratum rock stratum, and according to the thickness of the key stratum calculated in the step 2.2), considering the fracture degree of the rock stratum and the slurry filling rate, calculating the grouting quantity Q according to the following formula:
Figure BDA0003175369320000041
in the formula, lambda is a grouting loss coefficient; v is the grouting volume; eta is the fracture rate; epsilon is the slurry filling rate; m is the calculus rate of the serous fluid; wherein the grouting volume V expression is as follows:
V＝lwh (9)
wherein l is the reconstructed key layer inclination length; w is the strike length of the key layer; h reproducing the thickness of the key layer;
the calculation formula of the grouting time T is as follows:
Figure BDA0003175369320000042
in the formula, Q is the total grouting amount; c is the grouting amount per hour; n is the horizontal number of grouting; delta is the influence coefficient of the diameter change of the grouting pipeline;
step 3.3) construction process
And 3.3.1) the grouting work of the reconstructed key layer is finished in advance of two periods of pressure steps on the working face.
And 3.3.2) the first group of grouting holes are positioned right above the coal seam mining initial position, and in the implementation process, a hydraulic drilling machine is adopted to drill the grouting holes in the weak rock stratum section upwards from the two roadways, and sleeve arrangement is carried out.
Step 3.3.3) continuously extending the inclined grouting holes to a first horizontal position A1, arranging horizontal pipelines along the working face by using directional drilling, and grouting into the A1 horizontal drilling holes by using a high-pressure pump, wherein the grouting time T is determined by a formula (10);
and 3.3.4) standing for 5-7 hours after the horizontal grouting of the first group A1 is finished, continuously extending the inclined drilling holes to the second horizontal position A2, grouting according to an A1 horizontal grouting program, wherein the grouting time is T, standing for 5-7 hours, and completing all drilling hole grouting operations of the whole working surface according to the steps.
Has the beneficial effects that:
(1) unlike available passive and lagging control measures, such as increasing support resistance, raising support pillar activity, grouting around rock, etc. in stope, the present patent proposes the principle and method of re-creating key layer in the upper part of coal seam to slow down the pressure in stope.
(2) The invention provides a method for calculating the spatial position (spacing, inclination length and strike length) of a reconstructed key layer by fully considering the difference of the thickness and lithology of a coal bed; the quantitative cross-feed relation between the strength and the thickness of the key layer is established, a determination method for the strength and the thickness of the key layer is provided from the perspective of ensuring that the key layer does not slip and lose stability, and the quantitative design of the key layer reconstruction scheme is realized.
(3) The cross stepping bottom reverse grouting scheme is provided, parameters such as drilling hole arrangement, drilling hole diameter changing, grouting materials and grouting time are designed, and the scheme is reasonable in design and high in operability.
Drawings
FIG. 1a is a front view of the location of a reconstruction critical layer.
FIG. 1b is a left side view (FIG. 1a A-A section) of the location of a reconstruction critical layer.
FIG. 1c is a top view of the reconstruction critical layer location (FIG. 1a B-B section).
FIG. 2 shows the relationship between the thickness of the reconstructed critical layer and the strength.
Fig. 3a is a perspective view of a cross-step bottom-up reverse grouting scheme.
Fig. 3b is a perspective view of a single set of grouting lines.
Figure 3c is a projection of a single grout line (note: figure 3a projection of a single grout line along the dip of the coal seam).
Figure 3d is a projection of a single grout line (note: figure 3a single grout line projection along the strike of the coal seam).
Fig. 4 is a bar graph of rock at the working face of a mine 1101.
FIG. 5 is a table of different formation thicknesses versus compressive strength.
FIG. 6 is a graph of the thickness of different formations versus compressive strength.
FIG. 7a is a perspective view of a cross-step bottom-reverse grouting scheme of example 1.
FIG. 7b is a perspective view of a single set of grouting pipes according to embodiment 1.
FIG. 7c is a top projection view of the grouting pipe of example 1.
FIG. 7d is a perspective view of a single grouting pipe inclined along the coal seam according to example 1.
FIG. 7e is a projection view of a single grouting line along the strike direction of the coal seam in example 1.
In the figure, 1-coal seam; 2-reconstruction of the key layer; 3-weak rock formation; 4-return air tunnel; 5-a transportation roadway; 6-drilling a casing pipe; 7-horizontal grouting pipeline; l-reconstructed key layer propensity length; l' -face inclined length; w-the strike length of the reconstructed key layer; w' -working face strike length; h-height of the reconstructed key layer from the coal seam; h-reproducing the thickness of the key layer; beta-formation fracture angle; phi-the angle between the inclined bore and the top plate.
Detailed Description
A method for retarding stope mine pressure based on a key layer reconstruction principle comprises the following steps:
first step of on-site investigation and laboratory experiment
The lithology of the coal seam roof and the overlying strata, the thickness M of the coal seam, the thickness sigma h of the weak strata, the size of a working face, the fracture angle beta of the strata, the rotation angle theta of the strata, the fracture length a of a reconstructed key layer, the grouting loss coefficient lambda, the slurry filling rate epsilon, the slurry maturing rate M and the grouting amount c per hour are investigated on site; laboratory determination of compressive strength sigma of coal seam roof rock stratumcCoefficient of crushing expansion kiDensity rho, porosity eta, and influence coefficient delta of diameter change of a grouting pipeline;
secondly, determining the spatial position and thickness of the reconstructed key layer (as shown in figure 1)
Step 2.1) determining the spatial position of a reconstructed key layer
Based on the principle that the coal mining space can be filled due to the fact that the rock mass collapses and is subjected to crushing and expansion deformation after the coal seam is mined, determining the height H of the reconstructed key layer distance mining coal seam, wherein the expression is as follows:
Figure BDA0003175369320000061
in the formula, H is the height between the reconstructed key layer and the coal bed; delta is an influence coefficient, and the stability of a reconstructed key layer can be ensured when the delta is more than or equal to 90 percent; m is the thickness of the mined coal bed; k is a radical ofpThe expression of the composite crushing expansion coefficient of the caving rock mass is as follows:
Figure BDA0003175369320000062
in the formula, k1、k2………kiThe crushing and expansion coefficients of the 1 st and 2 … … i th rock layers above the coal bed are obtained;
considering the mining influence range after coal seam mining, determining the trend length l and the trend length w of the reconstructed key layer, wherein the expression is as follows:
Figure BDA0003175369320000063
w＝w'+20 (4)
wherein l' is the working face inclination length; w' is the working face trend length; h is the height between the reconstructed key layer and the coal seam; beta is the fracture angle of the rock stratum;
step 2.2) determining the thickness of the reconstructed critical layer
According to the forming condition of the key layer, simultaneously avoiding the key layer from slipping and destabilizing, determining the thickness of the reconstructed key layer, and expressing the following formula:
Figure BDA0003175369320000071
in the formula, h is the thickness of a reconstructed key layer; h is1Is the thickness of the loading layer; sigmacIn order to reproduce the compressive strength of the key layer; i is the critical block fracture degree; theta is a rock stratum rotation angle; rho is the density of the reconstructed key layer; g is the acceleration of gravity, wherein the expression of i is:
Figure BDA0003175369320000072
in the formula, h is the thickness of the reconstruction key layer; a is the breaking length of the reconstructed key layer; thickness h of the loading layer1The expression of (a) is:
h1＝∑h-∑hm-∑hl (7)
in the formula, sigma h is the total thickness of the weak rock stratum; sigma hmThe height of the collapse zone of the weak rock stratum; sigma hlIs the height of the weak formation fracture zone, wherein ∑ hm、∑hlThe determination formula is shown in table 1:
TABLE 1 determination formula for heights of collapse zone and fissure zone of weak rock stratum
Figure BDA0003175369320000073
Substituting the relevant parameters into the formula (5) to obtain the quantitative relation between the strength and the thickness of the reconstructed key layer, and drawing a relation curve between the strength and the thickness (as shown in figure 2). It should be noted that the relationship between the reconstructed critical layer thickness and the intensity determined by the formula (5) is a critical relationship, which is shown as C (h) in the figurec，σcc) For example, when the thickness of the reconstruction key layer is determined to be hcWhen the intensity is larger than or equal to σccThe requirement of forming a key layer and not causing slipping and instability can be met.
On the basis of FIG. 2, the basic condition σ is formed according to the critical layerc≥σc1And h is more than or equal to h1The optional range of the reconstruction key layer is determined, as shown by the shaded area, i.e. corresponding to the intensity and thickness combination in the AB curve and the area above it in the figure.
Third step key layer reconstruction grouting reinforcement design scheme
Step 3.1) arranging grouting pipes (as shown in figures 3a, 3b, 3c and 3 d)
Step 3.1.1) adopts a cross stepping bottom inverse grouting scheme to carry out pipeline arrangement: the staggered arrangement slip casting workstation in working face return air tunnel and haulage way promptly, the dislocation distance is 4 ~ 6m, separates for 8 ~ 11m between the slip casting workstation in same tunnel, and two adjacent slip casting workstations are a set of in two tunnels.
And 3.1.2) additionally arranging an inclined drilling hole from the roadway to the top plate, wherein the included angle phi between the inclined drilling hole and the top plate is 40-60 degrees, the vertical height of the drilling hole is (H + H), and the length of the pipeline is (H + H)/sin phi.
Step 3.1.3) dividing a grouting pipeline into two parts for better grouting reinforcement effect, wherein a casing is arranged in a slant drilling hole of a weak rock stratum section to prevent slurry from diffusing to an irrelevant rock stratum section, and the diameter of the drilling hole is 80-100 mm;
and 3.1.4) grouting and reinforcing the inclined drilling hole of the rock stratum section to be 50-70 mm in diameter, arranging a horizontal pipeline along the working face by using a directional drill, wherein the length is l/4, and the horizontal and vertical distance d is more than or equal to 3m and less than or equal to 5 m.
Step 3.2) determination of grouting material and grouting amount
Selecting different grouting materials and proportions according to the fracture rate of the reconstructed key stratum rock stratum, wherein the selection of the grouting materials is shown in the following table:
table 2 slip casting material selection table
Figure BDA0003175369320000081
According to the thickness of the key layer calculated in the step 2.2), considering the fracture degree of the rock stratum and the filling rate of the slurry, the calculation formula of the grouting quantity Q is as follows:
Figure BDA0003175369320000082
in the formula, lambda is a grouting loss coefficient; v is the grouting volume; eta is the fracture rate; epsilon is the slurry filling rate; m is the serous calculus rate; wherein the grouting volume V expression is as follows:
V＝lwh (9)
wherein l is the reconstructed key layer inclination length; w is the strike length of the key layer; h, reconstructing the thickness of the key layer;
the calculation formula of the grouting time T is as follows:
Figure BDA0003175369320000091
in the formula, Q is the total grouting amount; c is the grouting amount per hour; n is the horizontal number of grouting; and delta is the influence coefficient of the change of the diameter of the grouting pipeline, and is determined according to the length of the inclined drilling hole and the arrangement of the rock stratum in the cross-stepping bottom inverse grouting scheme.
Step 3.3) construction process
And 3.3.1) the grouting work of the reconstructed key layer is finished in advance of two periods of pressure steps on the working face.
And 3.3.2) the first group of grouting holes are positioned right above the coal seam mining initial position, and in the implementation process, a hydraulic drilling machine is adopted to drill grouting holes in the weak rock stratum section upwards from the two roadways, and sleeve arrangement is carried out.
Step 3.3.3) continuously extending the inclined grouting holes to a first horizontal position A1, arranging horizontal pipelines along the working face by using directional drilling, grouting into the A1 horizontal drilling holes by using a high-pressure pump, and determining grouting time T by using a formula (10);
and 3.3.4) standing for 5-7 hours after the horizontal grouting of the first group A1 is finished, continuously extending and obliquely drilling holes to a second horizontal position A2, grouting according to an A1 horizontal grouting program, wherein the grouting time is T, standing for 5-7 hours, and completing all drilling grouting operations of the whole working face according to the steps.
Example 1
First step of on-site investigation and laboratory experiment
As shown in fig. 4, a 3# coal seam is mainly mined on a working face of a certain mine 1101 in the western region by on-site investigation, the average thickness is 4m, an overburden rock layer is a weak rock layer with the thickness of 35m, the size of the working face is 150m × 100m, and a rock layer fracture angle β is 10 degrees; taking a rock stratum rotation angle theta of 20 degrees; the breaking length a of the key layer is reconstructed, and 14m is taken; taking 1.1 as a grouting loss coefficient lambda; taking the slurry filling rate epsilon to be 0.75; taking the setting rate m of the slurry to be 0.85; grouting amount c per hour, taking 1500m3H; and taking 1.2-1.5 as the influence coefficient delta of the diameter of the grouting pipeline.
The crushing expansion coefficient k of the weak rock stratum above the coal bed is measured in a laboratory1、k21.5 and 1.6 respectively; the density rho of the weak rock stratum is 2500g/m3(ii) a The porosity eta is 70%; compressive strength sigma of overburdencIs 30 MPa.
Second step reconstruction key layer space position and thickness determination
Step 2.1) reconstruction of spatial position of key layer
Step 2.1.1) determination of height H of reconstructed key layer from mining coal seam
Substituting the data of the first step into the formulas (1) and (2) to calculate the height H of the reconstructed key layer from the mining coal seam:
Figure BDA0003175369320000101
Figure BDA0003175369320000102
step 2.1.2) determining the dimensions of the reconstructed critical layer
And (3) substituting the data of the first step into formulas (3) and (4) to calculate the trend length l and the trend length w of the reconstructed key layer:
Figure BDA0003175369320000103
w＝w'+20＝150+20＝170m
step 2.2) determining the thickness of the reconstructed critical layer
Substituting the first step data into equations (6) and (7) to calculate the thickness h of the loading layer1：
Figure BDA0003175369320000104
Figure BDA0003175369320000105
h1＝∑h-∑hm-∑hl＝35-5.5-18.9＝10.6m
According to the formation condition of the key layer, meanwhile, the key layer is prevented from slipping and destabilizing, different rock stratum thickness and strength comparison tables are drawn, based on the key layer theory, when the rock stratum thickness is more than or equal to 7.5m and the strength is more than or equal to 30MPa, the rock stratum thickness and strength comparison tables can be used as the key layer, according to the different rock stratum thickness and compressive strength comparison tables (shown in figure 5) and the different rock stratum thickness and compressive strength comparison curves (shown in figure 6), a proper group of reconstructed key layer thicknesses and strengths are selected through a scheme comparison method and are substituted into a formula (5) to obtain:
Figure BDA0003175369320000106
by a scheme comparison method, the thickness of a reconstruction key layer is finally selected to be 8m and the strength is 35MPa in consideration of technical and economic benefits.
Third step key layer reconstruction scheme
Step 3.1) grouting pipeline arrangement
Step 3.1.1) adopts a cross stepping bottom inverse grouting scheme to carry out pipeline arrangement: namely, grouting workstations are arranged in a staggered mode in a working face air return roadway and a transport roadway, the staggered distance is 5m, the interval between the grouting workstations in the same roadway is 10m, and two adjacent grouting workstations in the two roadways form a group.
And 3.1.2) additionally arranging an inclined drilling hole to the top plate from the roadway, wherein the included angle phi between the inclined drilling hole and the top plate is 45 degrees, the vertical height of the drilling hole is 20.6m, and the length of the pipeline is 29.13 m.
And 3.1.3) dividing the grouting pipeline into two parts for better grouting reinforcement effect, wherein a sleeve is arranged in the inclined drill hole of the weak rock stratum section to prevent the slurry from diffusing to the irrelevant rock stratum section, and the diameter of the drill hole is 90 mm.
And 3.1.4) grouting and reinforcing the inclined drill hole of the rock stratum section to be 60mm in diameter, arranging a horizontal pipeline along the working face by using a directional drill, wherein the length of the horizontal pipeline is 25m, and the horizontal and vertical distance is 4 m.
Step 3.2) determination of grouting material and grouting amount
According to the results of field investigation, the porosity of the 1101 working face reconstructed key layer is 40%, the 1101 working face reconstructed key layer belongs to a low-porosity rock stratum, and the grouting material is selected to be ordinary cement-water glass double-slurry according to the grouting material table
And (3) substituting the first step data into the formulas (8), (9) and (10) according to the thickness and the strength of the key layer calculated in the step 2.2) to obtain:
V＝lwh＝145×170×4＝98600m3
Figure BDA0003175369320000111
Figure BDA0003175369320000112
step 3.3) construction process
And 3.3.1) the grouting work of the reconstructed key layer is finished in advance of two periods of pressure steps on the working face.
And 3.3.2) the first group of grouting holes are positioned right above the coal seam mining initial position, and in the implementation process, a hydraulic drilling machine is adopted to drill grouting holes in the weak rock stratum section upwards from the two roadways, and sleeve arrangement is carried out.
Step 3.3.3) continuously extending the inclined grouting holes to a first horizontal position A1, arranging horizontal pipelines along the working face by using a directional drill, and grouting into the A1 horizontal drill holes by using a high-pressure pump, wherein the grouting time is 10.6 hours;
and 3.3.4) standing for 5-7 hours after the horizontal grouting of the first group A1 is finished, continuously extending the inclined drilled holes to the second horizontal position A2, grouting according to an A1 horizontal grouting program, wherein the grouting time is 10.6 hours, standing for 5-7 hours, and completing all drilling grouting operations of the whole working face according to the steps.

Claims (6)

1. A method for retarding stope mine pressure based on a key layer reconstruction principle is characterized by comprising the following steps:
first step of on-site investigation and laboratory experiment
The method comprises the following steps of carrying out on-site investigation on the lithology of a coal seam roof and an overlying rock stratum thereof, the thickness M of the coal seam, the total thickness sigma h of a soft rock stratum, the size of a working face, a rock stratum fracture angle beta, a rock stratum rotation angle theta, a reconstructed key layer fracture length a, a grouting loss coefficient lambda, a slurry filling rate epsilon, a slurry setting rate M and a grouting amount c per hour; laboratory determination of compressive strength sigma of coal seam roof rock stratumcCoefficient of crushing expansion kiThe density rho and the porosity eta of the reconstructed key layer and the diameter change influence coefficient delta of the grouting pipeline;
second step, determining the spatial position and thickness of the reconstructed key layer
Step 2.1) determining the spatial position of a reconstructed key layer
Step 2.1.1) determining the height H of the reconstructed key layer from the mining coal seam
Based on the principle that the coal mining space can be filled due to the fact that the rock mass collapses and is subjected to crushing and expansion deformation after the coal seam is mined, determining the height H of the reconstructed key layer distance mining coal seam, wherein the expression is as follows:
Figure FDA0003669137180000011
in the formula, H is the height of the reconstructed key layer from the mined coal bed; delta is an influence coefficient, and generally, the stability of a reconstructed key layer can be ensured when the delta is more than or equal to 90 percent; m is the thickness of the mined coal bed; k is a radical ofpThe composite crushing expansion coefficient of the caving rock mass is expressed as follows:
Figure FDA0003669137180000012
in the formula, k1、k2………kiThe crushing and expansion coefficients of the 1 st and 2 … … i th rock layers above the coal bed are obtained;
step 2.1.2) determining the dimensions of the reconstructed critical layer
Considering the mining influence range after coal seam mining, determining the trend length l and the trend length w of the reconstructed key layer, wherein the expression is as follows:
Figure FDA0003669137180000013
w＝w'+20 (4)
wherein l' is the working face inclination length; w' is the working face trend length; h is the height of the reconstructed key layer from the mining coal seam; beta is the fracture angle of the rock stratum;
step 2.2) determining the thickness of the reconstructed critical layer
According to the forming condition of the key layer, simultaneously avoiding the key layer from slipping and destabilizing, determining the thickness of the reconstructed key layer, and expressing the following formula:
Figure FDA0003669137180000021
in the formula, h is the thickness of a reconstructed key layer; h is1Is the thickness of the loading layer; sigmacIn order to reproduce the compressive strength of the key layer; i is the critical block fracture degree; theta is a rock stratum rotation angle; rho is the density of the reconstructed key layer; g is the acceleration of gravity, wherein the expression of i is:
Figure FDA0003669137180000022
in the formula, h is the thickness of a reconstructed key layer; a is the breaking length of the reconstructed key layer; thickness h of the loading layer1The expression of (a) is:
h1＝∑h-∑hm-∑hl (7)
in the formula, sigma h is the total thickness of the weak rock stratum; sigma hmThe height of the collapse zone of the weak rock stratum; sigma hlThe height of a weak rock stratum fracture zone is obtained;
third step key layer reconstruction grouting reinforcement design scheme
Step 3.1) arranging grouting pipelines
Arranging pipelines by adopting a cross stepping bottom-inverse grouting scheme, additionally arranging inclined drill holes towards a top plate in a working face return air roadway and a transportation roadway, and dividing the inclined drill holes into a plurality of horizontal layers from bottom to top in the thickness range of a reconstructed key layer; arranging horizontal bores inclined along the working face around the inclined bores within a single horizontal layer;
step 3.2) determining grouting material and grouting amount
Selecting different grouting materials and proportions according to the fracture rate of the stratum of the reconstructed key layer, and according to the thickness of the reconstructed key layer calculated in the step 2.2), considering the fracture degree of the stratum and the slurry filling rate, calculating the total grouting quantity Q according to the following formula:
Figure FDA0003669137180000023
in the formula, lambda is a grouting loss coefficient; v is the grouting volume; eta is porosity; epsilon is the slurry filling rate; m is the calculus rate of the serous fluid; wherein the grouting volume V expression is as follows:
V＝lwh (9)
wherein l is the reconstructed key layer inclination length; w is the strike length of the key layer; h, reconstructing the thickness of the key layer;
the calculation formula of the grouting time T is as follows:
Figure FDA0003669137180000031
in the formula, T is grouting time; q is total grouting amount; c is the grouting amount per hour; n is the horizontal number of grouting; delta is the influence coefficient of the change of the diameter of the grouting pipeline, and is determined according to the length of the inclined drill hole and the arrangement of the rock stratum in the cross stepping bottom inverse grouting scheme;
step 3.3) construction process
The grouting work of the key layer reconstruction is finished in advance of two periodic pressure steps of the working face, the first group of grouting holes are located right above the coal seam mining initial position, in the implementation process, a hydraulic drilling machine is adopted to drill inclined grouting holes upwards from two roadways, after the inclined grouting holes reach a first horizontal position A1, a high-pressure pump is used for grouting in the A1 horizontal drilling holes, and the grouting time T is determined by a formula (10);
and after the horizontal grouting at the first horizontal position A1 is finished, standing for a period of time, continuing to extend the inclined drilling hole to a second horizontal position A2, and grouting according to a grouting program at the first horizontal position A1 to finish all drilling hole grouting operations of the whole working surface.
2. The method for relieving stope mine pressure based on key layer reconstruction principle as claimed in claim 1, wherein in step 2.2), the weak rock stratum caving zone height ∑ hmFormula and weak rock stratum fissure zone height ∑ hlThe formula is respectively determined by the lithology of the overlying strata and the uniaxial compressive strength/MPa:
when the overlying strata lithology is a hard rock stratum and the uniaxial compressive strength is 40-80MPa,
Figure FDA0003669137180000032
Figure FDA0003669137180000033
when the lithology of the overlying strata is a medium hard rock stratum and the uniaxial compressive strength is 20-40MPa,
Figure FDA0003669137180000034
Figure FDA0003669137180000035
when the lithology of the overlying strata is a weak rock stratum and the uniaxial compressive strength is 10-20MPa,
Figure FDA0003669137180000036
Figure FDA0003669137180000037
when the lithology of the overlying strata is an extremely soft rock stratum and the uniaxial compressive strength is less than 10MPa,
Figure FDA0003669137180000038
Figure FDA0003669137180000039
3. the method for relieving mine pressure of stope based on the key layer reconstruction principle of claim 1, wherein in the step 3.1), the sizes of the sections of the return air roadway and the transportation roadway are 3m in height and 4m in width.
4. The method for reducing stope mine pressure based on the key layer reconstruction principle according to claim 1, wherein in step 3.2), the included angle between an inclined drilling hole and a top plate is 40-60 degrees, the vertical height of the drilling hole is (H + H), the distance between adjacent grouting work stations in two roadways is 5m, the distance between the grouting work stations in the same roadway is 10m, the diameter of the inclined drilling hole in a weak rock stratum section is 80-100 mm, the diameter of the inclined drilling hole in a grouting reinforced rock stratum section is 50-70 mm, the vertical distance between adjacent horizontal layers is d, and d is more than or equal to 3m and less than or equal to 5 m; the length of a horizontal drilling hole is determined to be l/4 according to the size of a working face, and the diameter of the drilling hole is 50-70 mm.
5. The method for relieving stope mine pressure based on the key layer reconstruction principle of claim 1, wherein in the step 3.3), the selection and proportion of grouting materials are determined by fracture rate type and porosity;
under the conditions of high crack rate and porosity of 80-100%, the grouting material is formed by mixing A, B groups of materials, wherein the component A comprises sulfate cement, and the component B comprises lime and gypsum in a ratio of 0.6: 1;
under the condition of medium porosity of 50-80%, the grouting material is prepared by mixing A, B materials, wherein A component is sulfate cement, B component is lime and gypsum, and the proportion is 1.3: 1;
under the conditions of low crack rate and 35-50% of porosity, the grouting material is common cement-water glass double-slurry;
under the conditions of extremely low crack rate and porosity of less than 35%, the grouting material is ordinary sulfate cement with a water-cement ratio of 3.2: 1-2.8: 1.
6. The method for relieving mine pressure of a stope based on the key layer reconstruction principle according to claim 1, wherein in the step 3.3), the first horizontal position A1 is kept standing for 5-7 hours after horizontal grouting.
CN202110830519.2A 2021-07-22 2021-07-22 Method for relieving stope mine pressure based on key layer reconstruction principle Active CN113389549B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN202110830519.2A CN113389549B (en) 2021-07-22 2021-07-22 Method for relieving stope mine pressure based on key layer reconstruction principle
PCT/CN2022/101150 WO2023000920A1 (en) 2021-07-22 2022-06-24 Method for relieving stope mine pressure based on key layer reconstruction principle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110830519.2A CN113389549B (en) 2021-07-22 2021-07-22 Method for relieving stope mine pressure based on key layer reconstruction principle

Publications (2)

Publication Number Publication Date
CN113389549A CN113389549A (en) 2021-09-14
CN113389549B true CN113389549B (en) 2022-07-08

Family

ID=77626774

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110830519.2A Active CN113389549B (en) 2021-07-22 2021-07-22 Method for relieving stope mine pressure based on key layer reconstruction principle

Country Status (2)

Country Link
CN (1) CN113389549B (en)
WO (1) WO2023000920A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113389549B (en) * 2021-07-22 2022-07-08 山东科技大学 Method for relieving stope mine pressure based on key layer reconstruction principle
CN116167223B (en) * 2023-02-08 2024-02-13 中煤科工开采研究院有限公司 Method for determining artificial liberation layer
CN116380188B (en) * 2023-05-19 2023-11-03 山东科技大学 Effective water storage amount measuring method for goaf underground reservoir
CN117195526B (en) * 2023-08-31 2024-03-15 山东能源集团有限公司 Method and system for identifying roof targeting blasting stratum layer of working face of underground coal mine
CN117436291A (en) * 2023-12-21 2024-01-23 山东科技大学 Stope three-zone identification method based on overburden kinematics theory

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1129369A2 (en) * 1983-06-08 1984-12-15 Институт горного дела Севера Якутского филиала СО АН СССР Method of preparing geological disturbance zone to intersection by stoping drift
CN106869934B (en) * 2017-04-06 2018-08-31 安徽理工大学 A kind of slip casting recovery method suitable for inclined seam
CN107989613A (en) * 2017-11-14 2018-05-04 太原理工大学 A kind of overlying strata separation layer subregion isolates grouting filling working seam complete extraction method
CN112096380B (en) * 2020-01-17 2022-05-17 中国矿业大学(北京) High-strength mining rock stratum migration grouting control and grouting amount calculation method
AU2020100227A4 (en) * 2020-02-16 2020-03-26 Xi'an University Of Science And Technology Method for determining coal wall rib spalling of large mining-height fully-mechanized mining face of shallow coal seam
CN111810196B (en) * 2020-07-15 2022-02-11 中勘资源勘探科技股份有限公司 Method for reinforcing broken top plate through ground grouting
CN112377221B (en) * 2020-10-30 2022-09-23 中煤科工集团西安研究院有限公司 Method for inhibiting development of water guide crack belt by grouting before mining and building key layer of structure
CN113389549B (en) * 2021-07-22 2022-07-08 山东科技大学 Method for relieving stope mine pressure based on key layer reconstruction principle

Also Published As

Publication number Publication date
CN113389549A (en) 2021-09-14
WO2023000920A1 (en) 2023-01-26

Similar Documents

Publication Publication Date Title
CN113389549B (en) Method for relieving stope mine pressure based on key layer reconstruction principle
Li et al. Study on deformation failure mechanism and support technology of deep soft rock roadway
CN107526873B (en) Shallow tunnel surrounding rock collapse mode identification and supporting structure calculation method
CN103902780B (en) Solid filling coal mining earth's surface Deformation prediction method
CN106150546B (en) A kind of method that the filling of goaf part is carried out according to earth's surface subsidence
CN108194132B (en) A kind of pier formula multi-arch type Mined-out Area control method
WO2023000837A1 (en) Deep stope overburden rock type evaluation standard, and thickening reformation design method for thin bedrock
CN112377221B (en) Method for inhibiting development of water guide crack belt by grouting before mining and building key layer of structure
CN106150545B (en) A kind of method that the filling of goaf part is carried out according to roof caving feature
CN111734482A (en) Method for reducing damage by utilizing gangue cementation and bag grouting combined support
CN110617067A (en) Low-risk construction method for full-section boundary advanced pipe shed of extremely-soft surrounding rock tunnel
CN109854297A (en) A kind of coalfield mined-out Areas grouting method based on directional drilling technique
Zhang et al. Study on the large deformation characteristics and disaster mechanism of a thin-layer soft-rock tunnel
Zheng et al. Deformation mechanism and support technology of deep and high-stress soft rock roadway
AU2020202743A1 (en) Strip support method by using filler and residual coal pillar in irregular goaf
Shi et al. Research on key technologies of floor heave control in soft rock roadway
CN107448204A (en) Closely wear construction method of deep foundation ditch down in sandy gravel accumulation horizon shallow burial hidden digging tunnel
CN110284924B (en) Fully mechanized caving face gob-side entry retaining multi-layer filling body bearing structure and supporting method
Wu et al. Research on failure characteristics and zoning control technology of thick-soft surrounding rock for deep gob-side entry retaining
Tian et al. Study on the deformation failure mechanism and coupling support technology of soft rock roadways in strong wind oxidation zones
Huang et al. Performance research of materials and engineering application of overburden strata separation-zone grouting technology
BELL The history and techniques of coal mining and the associated effects and influence on construction
Zhang et al. Research on the deformation and control technology of surrounding rock in entry retaining along the gob side
Liu et al. Numerical studies on surrounding rock deformation controlled by pressure relief groove in deep roadway
Yao et al. Instability mechanism and surrounding rock control technology of roadway subjected to mining dynamic loading with short distance: A case study of the Gubei Coal Mine in China

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant