A method for distinguishing the types of water inrush from roof of coal mining working face

Abstract

The present invention belongs to the technical field of mine water hazard prevention and control, and specifically relates to a method for distinguishing the type of water inrush from the roof of a coal mining working face, comprising the following steps: S1: establishing an engineering geological disaster-pregnant environment model for water inrush from the roof of the overburden rock, and determining the main controlling layers of water-accumulating strata, water-conducting channels and strong mine pressure; S2: water accumulation assessment of the strata; S3: water-conducting channels and power sources assessment; S4: distinguishing the type of water inrush from the roof. The present invention fully considers the evolution mechanism of traditional water-conducting fissure water inrush and strata water inrush and the differences between the two, and establishes a calculation formula for the opening of the strata where water can accumulate in the overburden rock and a method for distinguishing rock stratum fracture based on the elastic-plastic theory, which can accurately predict whether water inrush will occur on the working face, accurately distinguish the type of water inrush from the roof, and identify whether the water inrush is accompanied by strong mine pressure and other events, thereby improving the safety production level of coal mines and reducing the risks and losses caused by water hazards.

Description

Technical Field

[0001] The invention belongs to the technical field of mine water hazard prevention and control, and particularly relates to a method for distinguishing the type of water inrush from the roof of a coal mining working face. Background Art

[0002] The coal mining face is the core area of ​​coal mining and is directly related to the extraction and transportation of resources. Due to the complex geological environment of coal mines, especially the deformation and movement of the roof rock strata, it has a vital impact on the safety and efficiency of the mining process. During the mining process, roof water inrush is one of the common and dangerous forms of water hazards. This type of water hazard will not only cause flooding of the working face and tunnels, but may also cause strong mine pressure and even cause chain disasters such as support collapse.

[0003] The traditional view is that roof water inrush is mainly caused by mining activities that cause water-conducting fissures to expand into the overlying aquifer, forming water inrush from water-conducting fissures. This type of water inrush is usually related to cracks or faults in the geological structure. Water quickly enters the mining face through these channels. The degree of harm caused by water inrush from water-conducting fissures depends on the size of the cracks and the amount of water.

[0004] As shallow coal seam resources are gradually exhausted, coal mining has shifted to deep and thick coal seams, especially in the Jurassic coal seam areas of the Ordos Basin. The complex engineering geological conditions in these areas have led to new types of water hazards: abscission water inrush;

[0005] Delamination water inrush is caused by the delamination and water accumulation of the rock layer above the roof aquifer. The mining disturbance causes the accumulated water in these delamination layers to instantly flow into the working face. Delamination water inrush is significantly instantaneous and sudden, and its instantaneous water inrush may exceed 1000m 3 / h. This severe water disaster can quickly submerge multiple mine working faces, causing production suspension and even casualties. Compared with traditional water-conducting fissure water inrush, the disaster-causing mechanism of stratum water inrush is more complicated, and there are significant differences in the treatment methods.

[0006] At present, there is a lack of an effective method to accurately identify the type of water inrush from the roof of a coal mining face, especially in the following aspects:

[0007] 1. Whether water inrush from the roof will occur: It is impossible to accurately predict whether water inrush from the working face will occur.

[0008] 2. Type of water inrush: It is impossible to determine whether the water inrush is a stratum water inrush or a traditional water-conducting fissure water inrush.

[0009] 3. Identification of accompanying events: It is unclear whether other dynamic disaster hazards such as strong mine pressure will occur during the water inrush.

[0010] This leads to a great blindness in the water hazard control methods of the working face. How to accurately identify the type of roof water inrush and take targeted and effective control measures is a major issue to ensure safe production in coal mines. Summary of the invention

[0011] The purpose of the present invention is to provide a method for distinguishing the type of water inrush from the roof of a coal mine mining face, which fully considers the evolution mechanism of traditional water-conducting fissure water inrush and stratum water inrush and the differences between the two, and establishes a calculation formula for the stratum aperture of overburden that can accumulate water and a method for distinguishing rock stratum fracture based on the elastic-plastic theory. It can accurately predict whether water inrush will occur on the working face, accurately distinguish the type of water inrush from the roof, and identify whether the water inrush is accompanied by events such as strong mine pressure, thereby improving the safety production level of coal mines and reducing the risks and losses caused by water disasters.

[0012] The technical solution adopted by the present invention is as follows:

[0013] A method for distinguishing the type of water inrush from the roof of a coal mining working face comprises the following steps:

[0014] S1: Establish an engineering geological disaster-prone environment model for water inrush from overburden roof caused by mining, and determine the main controlling layers of water accumulation, water-conducting channels and strong mine pressure;

[0015] S2: Assessment of water accumulation in the abscission zone;

[0016] S3: Assessment of water channels and power sources;

[0017] S4: Identification of roof water inrush types.

[0018] Furthermore, the S1 comprises the following steps:

[0019] S101: Construct “engineering geological model of mining-induced overburden”;

[0020] S102: Obtaining engineering geological conditions of overburden rock;

[0021] S103: Determine the main controlling strata for water accumulation, water-conducting channels and strong mineral pressure.

[0022] Furthermore, the S101 includes the following steps:

[0023] Collect geological data of the mining area and working face and construct a "mining overburden engineering geological model";

[0024] The geological data collected include exploration drilling data and hydrogeological information.

[0025] Furthermore, the engineering geological conditions of the overburden obtained in S102 include basic physical and mechanical parameters of the rock, the thickness of the rock layer, the relative distance between the rock layer and the coal seam, and the length and width of the working face.

[0026] Further, the S103 includes the following steps:

[0027] Determine the distance from the basic roof and floor of the coal mining face to the roof of the coal seam. Starting from the coal seam, determine from bottom to top whether the following relationship is met:

[0028] h i ≤M-(K p -1)∑h i-1 (1)

[0029] If it is satisfied, the rock layer belongs to the direct roof, and the next layer is judged, until a rock layer satisfies:

[0030] h i+1 >M-(K p -1)∑h i (2)

[0031] In the formula, h i is the thickness of the i-th rock layer; M is the mining height; K p is the average expansion coefficient of rock formations in collapse zones and fracture zones, which is 1.1-1.15; Σh i-1 is the cumulative thickness of the i-1 layers of rock above the coal seam roof;

[0032] The rock layer and the area above it are regarded as the basic top, that is, the distance between the basic top and bottom interface and the coal seam roof is

[0033] The basic roof below the roof aquifer is uniformly regarded as the main controlling layer of the potential water-accumulating stratum; the muddy aquiclude above the traditional water-conducting fracture zone and below the roof aquifer is regarded as the main controlling layer of the water-conducting channel; the hard rock layers such as igneous rocks above the aquifer or water-accumulating stratum are regarded as the main controlling layers of strong mineral pressure.

[0034] Further, the S2 comprises the following steps:

[0035] According to the ground settlement model, the actual separation space formed after the basic top deformation of the mining working face is calculated based on the following formula;

[0036]

[0037] Where, [w] is the actual separation space of the overburden caused by mining; K p The average expansion coefficient of rock formations in collapse zones and fracture zones is 1.1-1.15; It is the distance between the top interface of the main controlling stratum where water can accumulate and the roof of the coal seam; M is the mining height.

[0038] The main controlling layer of the potential water-accumulating stratum is regarded as an elastic fixed beam subjected to uniformly distributed load, and the bending moment of the fixed beam is:

[0039]

[0040] Where, q is the uniformly distributed load on the main controlling layer of the water-accumulating stratum; l is the span of the main controlling layer of the water-accumulating stratum, which is the strike length of the working face; x is the coordinate; M(x) is the bending moment;

[0041] According to the law of elastic-plastic mechanics, the curvatures of the plastic section and the elastic section of the main controlling stratum of the water-accumulating stratum under bending deformation are respectively expressed as follows:

[0042]

[0043] In the formula, and are the second-order derivatives of the plastic and elastic deflections of the main controlling stratum bending of the water-accumulating stratum, respectively; s is the plastic stress intensity of the main controlling layer of the water-accumulating stratum; b is the cross-sectional width of the main controlling layer of the water-accumulating stratum; h is the thickness of the main controlling layer of the water-accumulating stratum; E is the elastic modulus of the main controlling layer of the water-accumulating stratum;

[0044] By solving the calculus, we can get the deflection of the plastic section and elastic section of the main controlling layer of the water-accumulating stratum under bending deformation:

[0045]

[0046] In the formula, w 1 (x) and w 2 (x) are the deflections of the plastic section and the elastic section respectively; C 1 , C 2 , D 1 , D 2 is the unknown constant to be solved;

[0047] From the boundary conditions and continuity conditions: The unknowns are found as follows:

[0048] C 1 =0

[0049]

[0050] The total deflection of the main controlling layer of the water-accumulating stratum under bending deformation is the sum of the plastic section and the elastic section. The maximum deflection is taken at x = l / 2, that is, the maximum opening of the stratum when the main controlling layer of the water-accumulating stratum is about to enter plastic deformation:

[0051]

[0052] When the water-accumulating stratum opening reaches the disaster-causing opening w 0When the above value is reached, a disaster-causing delamination layer will be formed. Therefore, by comparing the actual delamination opening of the overburden with the disaster-causing opening and the main controlling layer of the water-accumulating delamination layer, the maximum deflection value w before plastic deformation can be obtained. max To determine the development of the water-accumulating abscission layer:

[0053] If the mining overburden satisfies w 0 <[w] <w max , indicating that the deflection value before the plastic failure of the main controlling layer of the water-accumulating abscission layer has reached the disaster-causing opening, which can form a continuous closed and large-scale abscission layer space, providing "time" and "space" conditions for the abscission layer to be filled with water and store groundwater;

[0054] If the mining overburden satisfies [w] <w 0 , or w max <w 0 , indicating that the actual deflection value of the main controlling layer of the water-accumulating abscission layer is less than the disaster-causing opening, or the deflection of the main controlling layer of the water-accumulating abscission layer after plastic damage still cannot reach the scale of the disaster-causing opening, so a large-scale abscission space cannot be formed, and the "spatial" conditions cannot be provided for the abscission layer to be filled with water and store groundwater, so no abscission water hazard will be formed;

[0055] If the mining overburden satisfies [w]>w max This indicates that during the actual mining period, the main controlling stratum of the water-accumulating abscission layer directly enters plastic failure, and cannot form a continuously closed abscission layer space that can accumulate water. It cannot provide the "time" conditions for the abscission layer to be filled with water and store groundwater, so no abscission water damage will occur.

[0056] Furthermore, S3 comprises the following steps:

[0057] S301: Determine the elastic-plastic limit load of the water channel and the main controlling layer of strong mine pressure;

[0058] The bending moment on the section in the elastic-plastic zone is:

[0059]

[0060] Where ξ is the height of the elastic core of any section of the beam; ρ is the radius of curvature;

[0061] make

[0062] The boundary equation of the plastic zone of the clamped beam is obtained as follows:

[0063]

[0064] If x = 0 or l, ξ = h / 2, we can get the load when the beam begins to yield, which is the elastic limit load of the beam.

[0065] If x = 0 or l, ξ = 0, we can get the load when the beam enters the plastic state, that is, the plastic limit load.

[0066] S302: Determine the actual load of the water channel and the main controlling layer of strong mine pressure;

[0067] According to the mining overburden structure model, the main control layer of the water channel is subject to the combined effects of water pressure, deadweight and the supporting force of the underlying rock strata, so its actual load is:

[0068] q d =P w +γh-R (13)

[0069] Where P w is the water pressure of the aquifer; γ is the gravity of the main controlling rock layer of the water channel; h is the thickness of the main controlling rock layer of the water channel; R is the supporting force of the underlying rock layer, R = λγh, λ is the supporting coefficient of the underlying rock layer to the main controlling rock layer of the water channel, which can be taken as 0.7~0.9. Therefore, the actual load of the main controlling layer of the water channel is:

[0070] q d =P w +(1-λ)γh (14)

[0071] The strong mine pressure main control layer is mainly subjected to its own weight and the overlying rock layer load. Assuming that the strong mine pressure main control layer and the overlying rock layer are rock layer i, rock layer i+1, rock layer i+2, ..., rock layer n in sequence; according to the combined rock beam theory, the total load on the strong mine pressure main control layer is:

[0072]

[0073] In the formula, E i and h i are the elastic modulus and thickness of the i-th rock layer respectively.

[0074] S303: Identification of the water channel of the mining face and the main control layer of strong mine pressure;

[0075] when and This indicates that the main control layer of the water channel is completely plastically destroyed, forming a water channel and causing roof water inrush, but the main control layer of the strong mine pressure is not broken and there is no strong mine pressure dynamic event;

[0076] when and This indicates that the main control layer of the water channel is completely plastically destroyed, forming a water channel, roof water inrush, and the main control layer of strong mine pressure is plastically destroyed, and the water inrush is accompanied by a strong mine pressure dynamic event;

[0077] when and This indicates that the main control layer of the water channel and the main control layer of the strong mine pressure are not broken, so the water channel cannot be formed, no roof water inrush occurs, and there is no strong mine pressure dynamic event;

[0078] when and This indicates that the main controlling layer of the water-conducting channel has not been broken, but if the main controlling layer of the strong mine pressure is broken, a water-conducting channel will still be formed, and no sudden roof water gushing will occur accompanied by strong mine pressure dynamic events.

[0079] Further, the types of roof water inrush in S4 include gradual strong mine pressure-separation water inrush, separation water inrush, sudden strong mine pressure-separation water inrush, separation water accumulation without water inrush, gradual strong mine pressure-water-conducting fissure water inrush, water-conducting fissure water inrush, sudden strong mine pressure-water-conducting fissure water inrush, no strong mine pressure-no water inrush;

[0080] The criterion for the gradual strong mine pressure-separation water inrush is:

[0081] w 0 <[w] <w max , and

[0082] The criterion for the delamination water inrush is:

[0083] w 0 <[w] <w max , and

[0084] The criterion for the sudden strong mine pressure-separation water inrush is:

[0085] w 0 <[w] <w max , and

[0086] The criterion for the absence of water in the separation layer is:

[0087] w 0 <[w] <w max , and

[0088] The gradual strong mine pressure-water-conducting fissure water inrush is:

[0089] [w]>w max or [w] <w0, and

[0090] The criterion for water inrush from water-conducting fissures is:

[0091] [w]>w maxor [w] <w 0 , and

[0092] The criterion for sudden strong mine pressure-water-conducting fissure water inrush is:

[0093] [w]>w max or [w] <w 0 , and

[0094] The criterion for no strong mine pressure and no water inrush is:

[0095] [w] <w 0 , and

[0096] The technical effects achieved by the present invention are:

[0097] The method for distinguishing the types of water inrush from the roof of a coal mining working face of the present invention fully considers the evolution mechanism of traditional water-conducting fissure water inrush and delamination water inrush and the differences between the two, establishes a calculation formula for the delamination opening of the overburden rock that can accumulate water and a method for distinguishing rock stratum fracture based on the elastic-plastic theory, and for the first time divides roof water hazards into eight types: including gradual strong mine pressure-delamination water inrush, delamination water inrush, sudden strong mine pressure-delamination water inrush, delamination water accumulation but no water inrush, gradual strong mine pressure-water-conducting fissure water inrush, water-conducting fissure water inrush, sudden strong mine pressure-delamination water inrush, delamination water accumulation but no water inrush, gradual strong mine pressure-water-conducting fissure water inrush, water-conducting fissure water inrush, sudden strong mine pressure-water-conducting fissure water inrush The eight types of discrimination methods, including modified strong mine pressure-water inrush from water-conducting fissures and no strong mine pressure-no water inrush, are proposed. They can accurately predict whether water inrush will occur at the working face, accurately discriminate the types of water inrush from the roof, especially distinguish between stratum water inrush and water inrush from water-conducting fissures, and identify whether water inrush is accompanied by strong mine pressure and other events. This will provide a scientific basis for water hazard management at the coal mining working face, thereby formulating targeted prevention and response measures, improving the safety production level of coal mines, and reducing the risks and losses caused by water hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Figure 1 It is a schematic diagram of the main controlling stratum structure of the overburden rock capable of accumulating water, the water-conducting channel and the strong ore pressure in the present invention;

[0099] Figure 2 It is a schematic structural diagram of a clamped beam model of the present invention;

[0100] Figure 3 The present invention is a flow chart of a method for distinguishing the type of water inrush from the roof of a coal mine mining working face. DETAILED DESCRIPTION

[0101] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific embodiments of the present invention, and does not strictly limit the scope of protection of the specific claims of the present invention.

[0102] Embodiment 1:

[0103] like Figure 1-3 As shown, a method for distinguishing the type of water inrush from the roof of a coal mining working face comprises the following steps:

[0104] S1: Establish an engineering geological disaster-prone environment model for water inrush from the overburden roof caused by mining, and determine the main controlling strata for water accumulation, water conduction channels and strong mine pressure.

[0105] Specifically, S1 includes the following steps:

[0106] S101: Construct “engineering geological model of mining-induced overburden”;

[0107] Specifically, the S101 includes the following steps:

[0108] First, collect geological data of the mining area and working face, which is the basis for establishing the engineering geological model of mining overburden. The geological data that needs to be collected include exploration drilling data, hydrogeological information, etc., focusing on obtaining detailed information about coal seams, lithology and aquifers; by analyzing the data of geological data, construct a simplified "engineering geological model of mining overburden". This model should clearly describe the mining characteristics of the coal seam, such as the thickness and burial depth of the coal seam and the width of the mining area or working face, and mark the spatial position of the water-accumulating strata and near-field roof rock layers, that is, their distance relative to the coal seam. In order to construct this model, it is necessary to integrate the hydrogeological data of the mining area or working face and the comprehensive stratigraphic columnar diagram and stratigraphic profile diagram to clarify the stratigraphic system, thickness, lithology, structure and burial depth of each rock layer, so as to identify the coal seam and the main aquifer and impermeable layer.

[0109] S102: Obtaining engineering geological conditions of overburden rock;

[0110] After completing the construction of the preliminary "engineering geological model of mining overburden", the specific engineering geological conditions of the overburden of the working face are further obtained through various methods such as field investigation, coring, and indoor testing. These engineering geological conditions include the basic physical and mechanical parameters of the rock, the thickness of the rock layer, the relative distance to the coal seam, and the length and width of the working face. These refined parameters are the key to judging and analyzing roof water inrush.

[0111] S103: Determine the main controlling strata for water accumulation, water-conducting channels and strong ore pressure;

[0112] After obtaining detailed geological conditions of the overburden, the next step is to determine the main controlling strata for water accumulation and the main controlling strata for strong ore pressure. This step needs to be combined with the established mining overburden engineering geological model to find out the main controlling strata that control the formation and development of water accumulation and the main controlling strata for the manifestation of strong ore pressure ( Figure 1 ).

[0113] Specifically, the S103 includes the following steps:

[0114] First, determine the distance from the basic roof and bottom plate of the coal mining face to the roof of the coal seam. Starting from the coal seam, determine from bottom to top whether the following relationship is met:

[0115] h i ≤M-(K p -1)∑h i-1 (16)

[0116] If it is satisfied, the rock layer belongs to the direct roof, and the next layer is determined until a rock layer satisfies:

[0117] h i+1 >M-(K p -1)∑h i (17)

[0118] In the formula, h i is the thickness of the i-th rock layer; M is the mining height; K p is the average expansion coefficient of rock formations in collapse zones and fracture zones, which is 1.1-1.15; ∑h i-1 It is the cumulative thickness of the i-1 rock layers above the coal seam roof.

[0119] The rock layer and the area above it are regarded as the basic top, that is, the distance between the basic top and bottom interface and the coal seam roof is

[0120] Since the water-accumulated strata of the Jurassic coalfield in my country are basically formed at the junction of the sandstone aquifer and its lower mudstone aquifer, the basic roof below the roof aquifer is regarded as the main controlling layer of the potential water-accumulated strata; the muddy aquifer above the traditional water-conducting fracture zone and below the roof aquifer is regarded as the main controlling layer of the water-conducting channel; the hard rock layers such as igneous rocks above the aquifer or water-accumulated strata are regarded as the main controlling layers of strong mine pressure ( Figure 1 ).

[0121] S2: Assessment of water accumulation in the abscission zone;

[0122] Specifically, S2 includes the following steps:

[0123] According to the stratum settlement model, the actual separation space formed after the basic top deformation of the mining working face is calculated based on the following formula.

[0124]

[0125] Where, [w] is the actual separation space of the overburden caused by mining; K p The average expansion coefficient of rock formations in collapse zones and fracture zones is 1.1-1.15; It is the distance between the top interface of the main controlling stratum where water can accumulate and the roof of the coal seam; M is the mining height.

[0126] The main controlling layer of the potential water-accumulating stratum is regarded as an elastic fixed beam under uniform load ( Figure 2 ), the bending moment of the fixed beam is:

[0127]

[0128] Where q is the uniformly distributed load on the main controlling layer of the water-accumulating stratum; l is the span of the main controlling layer of the water-accumulating stratum, which is the strike length of the working face; x is the coordinate; and M(x) is the bending moment.

[0129] According to the law of elastic-plastic mechanics, the curvatures of the plastic section and the elastic section of the main controlling stratum of the water-accumulating stratum under bending deformation are respectively related as follows:

[0130]

[0131] In the formula, and are the second-order derivatives (curvature) of the deflection of the plastic and elastic segments under the bending of the main controlling stratum of the water-accumulating stratum; σ s is the plastic stress intensity of the main controlling layer of the water-accumulating stratum; b is the cross-sectional width of the main controlling layer of the water-accumulating stratum, which can be taken as the working face width; h is the thickness of the main controlling layer of the water-accumulating stratum; E is the elastic modulus of the main controlling layer of the water-accumulating stratum.

[0132] By solving the calculus, we can get the deflection of the plastic section and elastic section of the main controlling layer of the water-accumulating stratum under bending deformation:

[0133]

[0134] In the formula, w 1 (x) and w 2 (x) are the deflections of the plastic section and the elastic section respectively; C 1 , C 2 , D 1 , D 2 is the unknown constant to be solved.

[0135] From the boundary conditions and continuity conditions: The unknowns are found as follows:

[0136] C 1 =0

[0137]

[0138] The total deflection of the main controlling layer of the water-accumulating stratum under bending deformation is the sum of the plastic section and the elastic section. The maximum deflection is taken at x = l / 2, that is, the maximum opening of the stratum when the main controlling layer of the water-accumulating stratum is about to enter plastic deformation:

[0139]

[0140] According to engineering experience, when the water accumulation stratum opening reaches more than 1m (disaster-causing opening w 0 ) will form a disaster-causing delamination layer. Therefore, by comparing the actual delamination opening of the overburden with the disaster-causing opening and the maximum deflection value w before the main controlling layer of the water-accumulating delamination layer enters plastic deformation max To determine the development of the water-accumulating abscission layer:

[0141] If the mining overburden satisfies w 0 <[w] <w max , indicating that the deflection value before the plastic failure of the main controlling layer of the water-accumulating abscission layer has reached the disaster-causing opening, which can form a continuously closed and large-scale abscission layer space, providing "time" and "space" conditions for the abscission layer to be filled with water and store groundwater.

[0142] If the mining overburden satisfies [w] <w 0 , or w max <w 0 , indicating that the actual deflection value of the main controlling layer of the water-accumulating abscission layer is less than the disaster-causing opening, or the deflection of the main controlling layer of the water-accumulating abscission layer after plastic damage still cannot reach the scale of the disaster-causing opening, so a large-scale abscission space cannot be formed, and the "spatial" conditions cannot be provided for the abscission layer to be filled with water and store groundwater. Therefore, abscission water damage will not occur.

[0143] If the mining overburden satisfies [w]>w max This indicates that during the actual mining period, the main controlling layer of the water-accumulating abscission layer directly entered plastic failure, and could not form a continuously closed water-accumulating abscission layer space, and could not provide the "time" conditions for the abscission layer to be filled with water and store groundwater. Therefore, no abscission water damage will occur.

[0144] S3: Assessment of water channels and power sources;

[0145] Specifically, S3 includes the following steps:

[0146] S301: Determine the elastic-plastic limit load of the water channel and the main controlling layer of strong mine pressure;

[0147] The bending moment on the section in the elastic-plastic zone is:

[0148]

[0149] Where ξ is the height of the elastic core of any cross section of the beam; ρ is the radius of curvature, and the other symbols are the same as before.

[0150] make

[0151] The boundary equation of the plastic zone of the clamped beam is obtained as follows:

[0152]

[0153] If x = 0 or l, ξ = h / 2, we can get the load when the beam begins to yield, which is the elastic limit load of the beam.

[0154] If x = 0 or l, ξ = 0, we can get the load when the beam enters the plastic state, that is, the plastic limit load.

[0155] S302: Determine the actual load of the water channel and the main controlling layer of strong mine pressure;

[0156] According to the mining overburden structure model, the main control layer of the water channel is subject to the combined effects of water pressure, deadweight and the supporting force of the underlying rock strata, so its actual load is:

[0157] q d =P w +γh-R (28)

[0158] Where P w is the water pressure of the aquifer; γ is the gravity of the main rock formation controlling the water channel; h is the thickness of the main rock formation controlling the water channel; R is the supporting force of the underlying rock formation, R = λγh, λ is the supporting coefficient of the underlying rock formation to the main rock formation controlling the water channel, which can be taken as 0.7~0.9.

[0159] Therefore, the actual load of the main control layer of the water channel is:

[0160] q d =P w +(1-λ)γh (29)

[0161] The main control layer of strong mine pressure is mainly subjected to its own weight and the load of the overlying rock layer. Assuming that the main control layer of strong mine pressure and the overlying rock layer are rock layer i, rock layer i+1, rock layer i+2, ..., rock layer n in sequence; according to the combined rock beam theory, the total load q on the main control layer of strong mine pressure is q for:

[0162]

[0163] In the formula, E i and h i are the elastic modulus and thickness of the i-th rock layer respectively.

[0164] S303: Identification of the water channel of the mining face and the main control layer of strong mine pressure;

[0165] when and This indicates that the main controlling layer of the water-conducting channel has been completely plastically destroyed, forming a water-conducting channel and causing water gushing from the roof, but the main controlling layer of the strong mine pressure has not been broken and there has been no strong mine pressure dynamic event.

[0166] when and This indicates that the main controlling layer of the water-conducting channel is completely plastically destroyed, forming a water-conducting channel, causing roof water gushing, and the main controlling layer of strong mine pressure is plastically destroyed, accompanied by strong mine pressure dynamic events during the water gushing.

[0167] when and This indicates that the main control layer of the water diversion channel and the main control layer of the strong mine pressure are not broken, so the water diversion channel cannot be formed, no water gushing from the roof occurs, and there is no strong mine pressure dynamic event.

[0168] when and This indicates that the main controlling layer of the water-conducting channel has not been broken, but if the main controlling layer of the strong mine pressure is broken, a water-conducting channel will still be formed, and no sudden roof water gushing will occur accompanied by strong mine pressure dynamic events.

[0169] S4: Identification of roof water inrush types;

[0170] According to the current relationship between mine roof water hazards and strong mine pressure chain disasters in my country, eight types of roof water inrush modes are divided, namely gradual strong mine pressure-separation water inrush, separation water inrush, sudden strong mine pressure-separation water inrush, separation water accumulation but no water inrush, gradual strong mine pressure-water-conducting fissure water inrush, water-conducting fissure water inrush, sudden strong mine pressure-water-conducting fissure water inrush, no strong mine pressure-no water inrush. The methods for distinguishing different types of water inrush are as follows:

[0171] Gradual strong mine pressure-ablation water inrush: This indicates that the deflection value before the plastic failure of the main controlling layer of the water-accumulating abscission layer has reached the disaster-causing opening, which can form a continuously closed and large-scale abscission space, providing the "time" and "space" conditions for the abscission layer to be filled with water and store groundwater. Subsequently, the main controlling layer of the water-conducting channel is completely plastically destroyed, forming a water-conducting channel, roof water inrush occurs, and the main controlling layer of the strong mine pressure is plastically destroyed, and the abscission water inrush is accompanied by a strong mine pressure dynamic event. The judgment criteria are as follows:

[0172] w 0 <[w] <w max , and

[0173] Water inrush from abscission: This indicates that the deflection value before the plastic failure of the main controlling layer of the water-accumulating abscission has reached the disaster-causing opening, which can form a continuously closed and large-scale abscission space, providing the "time" and "space" conditions for filling the abscission with water and storing groundwater. Subsequently, the main controlling layer of the water-conducting channel completely plastically destroyed, forming a water-conducting channel, and water inrush from the roof occurred, but the main controlling layer of the strong mine pressure did not undergo plastic failure, and there was no strong mine pressure dynamic event during the abscission water inrush. The judgment criteria are as follows:

[0174] w 0 <[w] <w max , and

[0175] Sudden strong mine pressure-absorptive water inrush: This indicates that the deflection value before the plastic failure of the main controlling layer of the water-accumulating absorptive layer has reached the disaster-causing opening, which can form a continuously closed and large-scale absorptive space, providing the "time" and "space" conditions for filling the absorptive layer with water and storing groundwater. The main controlling layer of the water-conducting channel did not undergo plastic failure, but the main controlling layer of the strong mine pressure did undergo plastic failure, forming a water-conducting channel instantly, and the absorptive water inrush was accompanied by a strong mine pressure dynamic event. The judgment criteria are as follows:

[0176] w 0 <[w] <w max , and

[0177] There is water accumulation in the abscission layer but no water gushing: This means that the deflection value before the plastic failure of the main controlling layer of the abscission layer that can accumulate water has reached the disaster-causing opening, which can form a continuous closed and large-scale abscission space, providing "time" and "space" conditions for the abscission layer to be filled with water and store groundwater. However, the main controlling layer of the water diversion channel and the main controlling layer of the strong mine pressure are not broken, so the water diversion channel cannot be formed, no roof water gushing occurs, and there is no strong mine pressure dynamic event. The judgment criteria are as follows:

[0178] w 0 <[w] <w max , and

[0179] Gradual strong mine pressure-water-conducting fissure water inrush: This indicates that the actual deflection value of the main controlling layer of the water-accumulating stratum is less than the disaster-causing opening, or the deflection of the main controlling layer of the water-accumulating stratum after plastic damage still cannot reach the scale of the disaster-causing opening, so a large-scale stratum space cannot be formed, and the "spatial" conditions cannot be provided for the stratum to be filled with water and store groundwater. However, the main controlling layer of the water-conducting channel is completely plastically destroyed, forming a water-conducting channel, roof water inrush occurs, and the main controlling layer of the strong mine pressure is plastically destroyed, and the water inrush is accompanied by a strong mine pressure dynamic event. The judgment criteria are as follows:

[0180] [w]>w max or [w] <w0 , and

[0181] Water gushing from water-conducting fissures: This indicates that the actual deflection value of the main controlling layer of the water-accumulating stratum is less than the disaster-causing opening, or the deflection of the main controlling layer of the water-accumulating stratum after plastic damage still cannot reach the scale of the disaster-causing opening, so a large-scale stratum space cannot be formed, and the "spatial" conditions cannot be provided for the stratum to be filled with water and store groundwater. Subsequently, the main controlling layer of the water-conducting channel completely plastically destroyed, forming a water-conducting channel, and roof water gushing occurred, but the main controlling layer of the strong mine pressure did not undergo plastic damage, and there was no strong mine pressure dynamic event during the water inrush. The judgment criteria are as follows:

[0182] [w]>w max or [w] <w 0 , and

[0183] Sudden strong mine pressure-water-conducting fissure water inrush: This indicates that the actual deflection value of the main controlling layer of the water-accumulating stratum is less than the disaster-causing opening, or the deflection of the main controlling layer of the water-accumulating stratum after plastic damage still cannot reach the scale of the disaster-causing opening, so a large-scale stratum space cannot be formed, and the "spatial" conditions for filling the stratum with water and storing groundwater cannot be provided. The main controlling layer of the water-conducting channel did not undergo plastic damage, but the main controlling layer of the strong mine pressure did undergo plastic damage, forming a water-conducting channel instantly, and the water inrush was accompanied by a strong mine pressure dynamic event. The judgment criteria are as follows:

[0184] [w]>w max or [w] <w 0 , and

[0185] No strong mine pressure - no water gushing: This means that the actual deflection value of the main controlling layer of the water-accumulating abscission layer is less than the disaster-causing opening, so a large-scale abscission space cannot be formed, and the "spatial" conditions cannot be provided for the abscission layer to be filled with water and store groundwater. Therefore, no abscission water hazard will be formed. In addition, the main controlling layer of the water diversion channel and the main controlling layer of strong mine pressure are not broken, so the water diversion channel cannot be formed, no roof water gushing occurs, and there is no strong mine pressure dynamic event. The judgment criteria are as follows:

[0186] [w] <w 0 , and

[0187] The characteristics of different types of water inrush are shown in Table 1. On the basis of clarifying the types and characteristics of water inrush at the working face, targeted measures are taken to prevent and control it. Figure 3 shown.

[0188] Table 1 Characteristics of different types of water inrush

[0189]

[0190] Embodiment 2:

[0191] This embodiment, in conjunction with the accompanying drawings, describes in detail a method for distinguishing the type of water inrush from the roof of a coal mining face. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0192] Taking Cuimu Coal Mine in Yonglong Mining Area of ​​Ordos Basin as an example, the above method for distinguishing the types of roof water inrush in coal mining working faces was applied to the 22303 working face of Cuimu Coal Mine.

[0193] S1: Establish an engineering geological disaster-prone environment model for water inrush from overburden roof caused by mining, and determine the main controlling layers of water accumulation, water-conducting channels and strong mine pressure;

[0194] This embodiment takes the 22303 working face of Cuimu Coal Mine as an example, obtains comprehensive stratigraphic conditions by taking stratigraphic data, and divides the comprehensive stratigraphic rock group, as shown in Table 2. According to the engineering hydrogeological conditions of Cuimu Coal Mine, the coarse sandstone at the bottom of the Cretaceous Luohe Formation aquifer can be regarded as the main controlling layer of strong mine pressure, the mudstone layer of the Jurassic Anding Formation is the main controlling layer of the water channel, and the fine sandstone and sandy mudstone above the direct top are the main controlling layers of the water-accumulating strata. The working face width is 185m, the strike length is 1100m, and the average mining height is 12m.

[0195] Table 2 Strata conditions of 22303 working face in Cuimu Coal Mine

[0196]

[0197] S2: Assessment of water accumulation in the abscission zone;

[0198] Substituting the parameters in Table 3 into formula (9), we can obtain that the deflection of the main controlling layer of the water-accumulating stratum after plastic failure is 5.74 m, and the actual deflection value of the main controlling layer of the water-accumulating stratum is 3.45 m. 0 <[w] <w max , indicating that the deflection value before the plastic failure of the main controlling layer of the water-accumulating abscission layer has reached the disaster-causing opening, which can form a continuously closed and large-scale abscission layer space, providing "time" and "space" conditions for the abscission layer to be filled with water and store groundwater.

[0199] Table 3 Calculation parameters for the fracture criterion of the upper rock layer and the lower aquiclude

[0200]

[0201]

[0202] S3: Assessment of water channels and power sources;

[0203] Substituting the parameters in Table 2 into equations (14) and (15), we obtain and This indicates that the main controlling layer of the water-conducting channel is completely plastically destroyed, forming a water-conducting channel, causing roof water gushing, and the main controlling layer of strong mine pressure is plastically destroyed, accompanied by strong mine pressure dynamic events during the water gushing.

[0204] S4: Identification of roof water inrush types;

[0205] In summary, the 22303 working face of Cuimu Coal Mine meets the following requirements:

[0206] w 0 <[w] <w max , and

[0207] This indicates that the deflection value before the plastic failure of the main controlling layer of the water-accumulating abscission layer has reached the disaster-causing opening, which can form a continuously closed and large-scale abscission space, providing the "time" and "space" conditions for the abscission layer to be filled with water and store groundwater. Subsequently, the main controlling layer of the water-conducting channel completely plastically destroyed, forming a water-conducting channel, roof water inrush, and the main controlling layer of strong mine pressure plastically destroyed, and the abscission water inrush was accompanied by a strong mine pressure dynamic event. Therefore, it can be determined that the working face is a gradual strong mine pressure-abscission water inrush.

[0208] In summary, this technical solution fully considers the evolution mechanism of traditional water-conducting fissure water inrush and delamination water inrush and the differences between the two. Based on the elastic-plastic theory, the calculation formula for the delamination aperture of the overburden rock that can accumulate water and the method for distinguishing rock stratum fracture are established. For the first time, roof water hazards are divided into eight types: including gradual strong mine pressure-delamination water inrush, delamination water inrush, sudden strong mine pressure-delamination water inrush, delamination water accumulation but no water inrush, gradual strong mine pressure-water-conducting fissure water inrush, water-conducting fissure water inrush, sudden strong mine pressure-water-conducting The eight types of identification methods, including fissure water inrush and no strong mine pressure - no water inrush, can accurately predict whether water inrush will occur at the working face, accurately identify the type of roof water inrush, especially distinguish between stratum water inrush and water-conducting fissure water inrush, and identify whether the water inrush is accompanied by strong mine pressure and other events. This will provide a scientific basis for water hazard management at the coal mining working face, thereby formulating targeted prevention and response measures, improving the safety production level of coal mines, and reducing the risks and losses caused by water hazards.

[0209] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art unless otherwise specified and limited.

Claims

1. A method for distinguishing the type of water inrush from the roof of a coal mining working face, characterized in that: The following steps are involved: S1: Establish an engineering geological disaster-prone environment model for water inrush from overburden roof caused by mining, and determine the main controlling layers of water accumulation, water-conducting channels and strong mine pressure; S2: Delamination water accumulation assessment: Calculate the actual delamination opening formed after the basic top deformation of the mining working face; The main controlling layer of the potential water-accumulating stratum is regarded as an elastic fixed beam under uniform load, and the maximum deflection value of the main controlling layer of the water-accumulating stratum is calculated when it is about to enter plastic deformation; the development of water accumulation in the stratum is evaluated by comparing the actual stratum opening and disaster-causing opening of the overburden with the maximum deflection value of the main controlling layer of the water-accumulating stratum before entering plastic deformation; S3: Assessment of water channel and power source: Based on elastic-plastic mechanics, determine the elastic-plastic limit load of the water channel and the main control layer of strong mine pressure, as well as the actual load on the water channel and the main control layer of strong mine pressure; by comparing the elastic-plastic limit load with the actual load, assess the formation of the water channel and power source of the mining face; S4: Identification of roof water inrush types: By comprehensively comparing the actual stratum opening of the overburden with the disaster-causing opening, the maximum deflection value of the main controlling layer of the water-accumulating stratum before plastic deformation, and by comparing the elastoplastic limit loads of the water-conducting channel and the main controlling layer of strong mine pressure with the actual loads borne by the water-conducting channel and the main controlling layer of strong mine pressure, the type of roof water inrush can be identified.

2. A method for distinguishing the type of water inrush from the roof of a coal mining working face according to claim 1, characterized in that: The S1 comprises the following steps: S101: Construct "engineering geological model of mining-induced overburden" to identify coal seams and major aquifers and impermeable layers; S102: Obtaining engineering geological conditions of overburden rock; S103: The basic roof below the roof aquifer is regarded as the main controlling layer of the potential water-accumulating stratum; the muddy aquiclude above the traditional water-conducting fracture zone and below the roof aquifer is regarded as the main controlling layer of the water-conducting channel; the igneous rock above the aquifer or water-conducting stratum is regarded as the main controlling layer of the strong ore pressure, and the main controlling layers of the water-conducting stratum, water-conducting channel and strong ore pressure are determined; The S101 includes the following steps: Collect geological data of the mining area and working face and construct a "mining overburden engineering geological model"; The geological data collected include exploration drilling data, hydrogeological information; The engineering geological conditions of the overburden obtained in S102 include basic physical and mechanical parameters of the rock, the thickness of the rock layer, the relative distance between the rock layer and the coal seam, and the length and width of the working face; The S103 comprises the following steps: Determine the distance from the basic roof and floor of the coal mining face to the roof of the coal seam. Starting from the coal seam, determine from bottom to top whether the following relationship is met: h i ≤M-(K p -1)∑h i-1 (1) If it satisfies, the rock layer belongs to the direct roof, and the next layer is judged, until a rock layer satisfies: h i+1 >M-(K p -1)∑h i (2) In the formula, h i is the thickness of the i-th rock layer; M is the mining height; K p is the average expansion coefficient of rock formations in collapse zones and fracture zones, which is 1.1-1.15; ∑h i-1 is the cumulative thickness of the i-1 layers of rock above the coal seam roof; The rock layer and the area above it are regarded as the basic top, that is, the distance between the basic top and bottom interface and the coal seam roof is The basic roof below the roof aquifer is regarded as the main controlling layer of the potential water-accumulating stratum; the muddy aquiclude above the traditional water-conducting fracture zone and below the roof aquifer is regarded as the main controlling layer of the water-conducting channel; the igneous rock above the aquifer or water-accumulating stratum is regarded as the main controlling layer of the strong mineral pressure.

3. A method for distinguishing the type of water inrush from the roof of a coal mining working face according to claim 2, characterized in that: The S2 comprises the following steps: According to the ground settlement model, the actual separation space formed after the basic top deformation of the mining working face is calculated based on the following formula; Where, [w] is the actual separation space of the overburden caused by mining; K p The average expansion coefficient of rock formations in collapse zones and fracture zones is 1.1-1.15; is the distance between the top interface of the main controlling stratum that can accumulate water and the coal seam roof; M is the mining height; The main controlling layer of the potential water-accumulating stratum is regarded as an elastic fixed beam subjected to uniformly distributed load, and the bending moment of the fixed beam is: Where, q is the uniformly distributed load on the main controlling layer of the water-accumulating stratum; l is the span of the main controlling layer of the water-accumulating stratum, which is the strike length of the working face; x is the coordinate; M(x) is the bending moment; According to the law of elastic-plastic mechanics, the curvatures of the plastic section and the elastic section of the main controlling stratum of the water-accumulating stratum under bending deformation are respectively related as follows: In the formula, and are the second-order derivatives of the plastic and elastic deflections of the main controlling stratum bending of the water-accumulating stratum, respectively; s is the plastic stress intensity of the main controlling layer of the water-accumulating stratum; b is the cross-sectional width of the main controlling layer of the water-accumulating stratum; h is the thickness of the main controlling layer of the water-accumulating stratum; E is the elastic modulus of the main controlling layer of the water-accumulating stratum; By solving the calculus, we can get the deflection of the plastic section and elastic section of the main controlling layer of the water-accumulating stratum under bending deformation: Where w1(x) and w2(x) are the deflections of the plastic section and the elastic section respectively; C1, C2, D1, D2 are unknown constants to be solved; From the boundary conditions and continuity conditions: The unknowns are found as follows: C1＝0 The total deflection of the main controlling layer of the water-accumulating stratum under bending deformation is the sum of the plastic section and the elastic section. The maximum deflection is taken at x = l / 2, that is, the maximum opening of the stratum when the main controlling layer of the water-accumulating stratum is about to enter plastic deformation: When the water-accumulating stratum opening reaches above the disaster-causing opening w0, a disaster-causing stratum will be formed. Therefore, by comparing the actual stratum opening of the overburden with the disaster-causing opening and the maximum deflection value w before the main controlling layer of the water-accumulating stratum enters plastic deformation, the max To determine the development of the water-accumulating abscission layer: If the mining overburden satisfies w0<[w] <w max , indicating that the deflection value before the plastic failure of the main controlling layer of the water-accumulating abscission layer has reached the disaster-causing opening, which can form a continuous closed and large-scale abscission layer space, providing "time" and "space" conditions for the abscission layer to be filled with water and store groundwater; If the mined-overlying strata satisfy [w] < w0, or there is w max < w0, it indicates that the actual deflection value of the main control layer of the water-accumulating separated strata is less than the disaster-causing opening degree, or the deflection after the plastic failure of the main control layer of the water-accumulating separated strata still cannot reach the scale of the disaster-causing opening degree. Therefore, a large-scale separated strata space cannot be formed, and the "space" condition for filling the separated strata with water and storing groundwater cannot be provided. Therefore, separated strata water disasters will not occur; If the mining overburden satisfies [w]>w max This indicates that during the actual mining period, the main controlling stratum of the water-accumulating abscission layer directly enters plastic failure, and cannot form a continuously closed abscission layer space that can accumulate water. It cannot provide the "time" conditions for the abscission layer to be filled with water and store groundwater, so no abscission water damage will occur.

4. A method for distinguishing the type of water inrush from the roof of a coal mining working face according to claim 3, characterized in that: The S3 comprises the following steps: S301: Determine the elastic-plastic limit load of the water channel and the main controlling layer of strong mine pressure; The bending moment on the section in the elastic-plastic zone is: Where ξ is the height of the elastic core of any section of the beam; ρ is the radius of curvature; make The boundary equation of the plastic zone of the clamped beam is obtained as follows: Let x = 0 or l, ξ = h / 2, and we can get the load when the beam begins to yield, that is, the elastic limit load of the beam. Let x = 0 or l, ξ = 0, and we can get the load when the beam enters the plastic state, that is, the plastic limit load S302: Determine the actual load of the water channel and the main controlling layer of strong mine pressure; According to the mining overburden structure model, the main control layer of the water channel is subject to the combined effects of water pressure, deadweight and the supporting force of the underlying rock strata, so its actual load is: q d =P w +γh-R (13) Where P w is the water pressure of the aquifer; γ is the weight of the main controlling rock layer of the water channel; h is the thickness of the main controlling layer of the water-accumulating stratum; R is the supporting force of the underlying rock layer, R = λγh, λ is the supporting coefficient of the underlying rock layer to the main controlling rock layer of the water channel, which is 0.7-0.9; therefore, the actual load of the main controlling layer of the water channel is: q d =P w +(1-λ)γh (14) The strong mine pressure main control layer is mainly subjected to its own weight and the overlying rock layer load. Assuming that the strong mine pressure main control layer and the overlying rock layer are rock layer i, rock layer i+1, rock layer i+2, ..., rock layer n in sequence; according to the combined rock beam theory, the total load on the strong mine pressure main control layer is: In the formula, Λ i and h i are the elastic modulus and thickness of the i-th rock layer respectively; S303: Identification of the water channel of the mining face and the main control layer of strong mine pressure; when and This indicates that the main control layer of the water channel is completely plastically destroyed, forming a water channel and causing roof water inrush, but the main control layer of the strong mine pressure is not broken and there is no strong mine pressure dynamic event; when and This indicates that the main control layer of the water channel is completely plastically destroyed, forming a water channel, roof water inrush, and the main control layer of strong mine pressure is plastically destroyed, and the water inrush is accompanied by a strong mine pressure dynamic event; when and This indicates that the main control layer of the water channel and the main control layer of the strong mine pressure are not broken, so the water channel cannot be formed, no roof water inrush occurs, and there is no strong mine pressure dynamic event; when and This indicates that the main controlling layer of the water-conducting channel has not been broken, but if the main controlling layer of the strong mine pressure is broken, a water-conducting channel will still be formed, and no sudden roof water gushing will occur accompanied by strong mine pressure dynamic events.

5. A method for distinguishing the type of water inrush from the roof of a coal mining working face according to claim 4, characterized in that: The types of roof water inrush in S4 include gradual strong mine pressure-detachment water inrush, detachment water inrush, sudden strong mine pressure-detachment water inrush, detachment water accumulation but no water inrush, gradual strong mine pressure-water-conducting fissure water inrush, water-conducting fissure water inrush, sudden strong mine pressure-water-conducting fissure water inrush, and no strong mine pressure-no water inrush.

6. A method for distinguishing the type of water inrush from the roof of a coal mining working face according to claim 5, characterized in that: The criterion for the gradual strong mine pressure-separation water inrush is: w0<[w] <w max , and The criterion for the delamination water inrush is: w0<[w] <w max , and The criterion for the sudden strong mine pressure-separation water inrush is: w0<[w] <w max , and The criterion for the absence of water in the separation layer is: w0<[w] <w max , and The gradual strong mine pressure-water-conducting fissure water inrush is: [w]>w max or [w] <w0, and The criterion for water inrush from water-conducting fissures is: [w]>w max or [w] <w0, and The criterion for sudden strong mine pressure-water-conducting fissure water inrush is: [w]>w max or [w] <w0, and The criterion for no strong mine pressure and no water inrush is: [w] <w0, and Wherein, w0 represents the water-causing opening of the abscission layer; [w] represents the deflection value of the main controlling layer of the abscission layer before plastic failure; max It indicates the maximum deflection value of the main controlling layer of the water-accumulating stratum before it enters plastic deformation.

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