Rock hydraulics-based high-level separation layer water monitoring and drainage control method

Abstract

The invention discloses a rock hydraulics-based high-position separation water monitoring and drainage control method, which comprises the following steps of: determining a separation water development position according to an early-stage exploration result; a monitoring drill hole and a drainage drill hole which are communicated with the separation water are constructed on the ground surface above the development position of the separation water; a water pressure sensor is arranged at the bottom in the monitoring drill hole; a water suction pump is arranged in the drainage drill hole; a plurality of micro-seismic sensors are arranged in a roof rock stratum of the working face at set intervals, and the development height of the water flowing fractured zone is determined according to micro-seismic signals collected by the micro-seismic sensors; determining the thickness of a separation layer water-resisting layer according to the development height of the water flowing fractured zone; determining an abscission water warning water head according to the thickness of the abscission water water-resisting layer; determining a warning water level according to the separation water warning water head and the separation water bottom plate elevation obtained through early-stage exploration, and setting the determined separation water warning water level as an early warning water level; the water level data in the monitoring drill hole are collected in real time, the real-time water level is obtained, when the real-time water head exceeds the early warning water level, the water suction pump is started to pump separation water, and separation water level control is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of prevention and control of water in the separated aquifer in the roof of coal mines, and particularly relates to a method for controlling the drainage of high-level separated water based on rock mass hydraulics. Background Technique

[0002] During the mining process of Jurassic coal seams in the western region, since the coal seam thickness is generally 7 - 10 m, top coal caving mining is usually adopted. The caving zone of the coal seam is large, and the development height of the water-conducting fissure zone is large. Due to the existence of separated water in the coal seam in the interbedded layers of sandstone, mudstone, and shale, and the large rigidity difference between the sandstone aquifer and the sand-mudstone aquifer, uneven settlement occurs in the rock strata above the water-conducting fissure zone, forming high-level separated water. The existence of high-level separated water poses a serious threat to the safe production of mines. With the increase of mining depth and intensity, water inrush and water bursting accidents caused by high-level separated water occur frequently, bringing huge economic losses and casualties to coal mining enterprises. At present, the prevention and control of separated water mainly rely on active drainage. The problems faced by this operation are as follows: The development position of high-level separated water is relatively high, the distance from the coal seam being mined is more than 150 m, and the roof of the coal seam is Jurassic strata with a short diagenetic time, weak rock mechanical properties, easy to collapse holes, and great difficulty in constructing water discharge holes underground. Large drainage volume will waste underground water resources and affect the groundwater environment. Existing monitoring of separated water has problems such as too many monitoring parameters, poor control effect, lack of theoretical basis for early warning, and difficulty in determining the early warning water level, and urgent improvement is needed. Summary of the Invention

[0003] The purpose of the invention is to provide a method for monitoring and controlling the drainage of high-level separated water based on rock mass hydraulics, analyze the situation of the high-level separated aquifer according to the data collected during the monitoring process, and issue warnings for possible abnormal accidents, so as to improve construction safety and efficiency.

[0004] To solve the above problems, the invention adopts the following technical solutions:

[0005] A method for monitoring and controlling the drainage of high-level separated water based on rock mass hydraulics, comprising the following steps:

[0006] Step 1: Determine the roof rock stratum structure, rock mechanical properties, and key stratum theory of the coal mining face according to the preliminary exploration results, and determine the development position of the separated water;

[0007] Step 2: Construct monitoring boreholes and drainage boreholes on the ground above the determined development position of the separated water to communicate with the separated water;

[0008] Step 3: Place a water pressure sensor at the bottom inside the monitoring borehole; install a water pump inside the drainage borehole;

[0009] Step 4: Arrange multiple microseismic sensors at intervals in the roof rock formations of the upper gate roadway and the lower gate roadway of the coal face respectively; determine the development height of the water-conducting fissure zone according to the microseismic signals collected by the microseismic sensors.

[0010] Step 5: Determine the thickness of the separated seam water aquiclude according to the development height of the water-conducting fissure zone.

[0011] Step 6: Determine the warning water head of the separated seam water according to the thickness of the separated seam water aquiclude; determine the warning water level according to the warning water head of the separated seam water and the floor elevation of the separated seam water obtained from the previous exploration, and set the determined warning water level of the separated seam water as the warning water level for early warning.

[0012] Step 7: Collect the water level data in the monitoring borehole in real time through the water pressure sensor to obtain the real-time water level. When the real-time water head exceeds the warning water level, start the water pump to pump out the separated seam water to realize the control of the separated seam water level.

[0013] The present invention also has the following technical features:

[0014] Specifically, the said Step 1 specifically includes the following sub-steps:

[0015] Step 1.1: Determine the key strata according to the roof rock formation structure, rock mechanical properties and key strata theory of the coal face based on the previous exploration results.

[0016] Step 1.2: Establish a geological model of the coal seam to be mined and complete the simulation of the mining process to obtain the simulation results of the strata displacement and stress change during the mining process.

[0017] Step 1.3: Determine the development position of the separated seam water according to the obtained simulation results of the strata displacement and stress change.

[0018] Furthermore, the said monitoring borehole is arranged at the center of the square of the coal face during mining, and the distance between the end hole position and the floor of the separated seam water is 1 - 1.5 m.

[0019] Furthermore, the interval set in Step 4 is 100 m.

[0020] Furthermore, in the said Step 5, the thickness of the separated seam water aquiclude is determined by the following formula:

[0021] h = h1 - h2

[0022] In the formula:

[0023] h is the thickness of the separated seam water aquiclude, with the unit of m;

[0024] h1 is the distance between the separated seam water and the top surface of the coal seam, with the unit of m;

[0025] h2 is the development height of the water-conducting fissure zone, with the unit of m.

[0026] Furthermore, the warning water head of the separated seam water is determined by the following formula in step 6:

[0027]

[0028] In the formula:

[0029] H is the warning water head of the separated seam water, with the unit of MPa;

[0030] h is the thickness of the water - resistant layer of the separated seam water, with the unit of m;

[0031] σ T is the tensile strength of the water - resistant layer, with the unit of MPa;

[0032] γ w is the specific gravity of water, with the unit of kg / m 3 ;

[0033] L is the inclined length of the working face, with the unit of m;

[0034] K is the safety factor.

[0035] Furthermore, the warning water level is determined according to the warning water head of the separated seam water and the floor elevation of the separated seam water obtained from the previous exploration in step 6, which is realized by the following formula:

[0036] H 水位 = H + H0

[0037] Wherein,

[0038] H 水位 is the warning water level, with the unit of m;

[0039] H is the warning water head of the separated seam water, with the unit of m;

[0040] H0 is the floor elevation of the separated seam water, with the unit of m.

[0041] Compared with the prior art, the present invention has the following technical effects:

[0042] (1) The present invention uses the microseismic monitoring and separated seam water level methods to obtain information on the upper separated seam water from different angles, effectively improving the monitoring accuracy; by using the method of the present invention, the formation, migration and water pressure change of the separated seam water can be detected in time, providing reliable data support for subsequent control and warning.

[0043] (2) The method of the present invention accurately divides the development height of the roof water-conducting fissure zone through the quantitative calculation of the roof failure range by the microseismic event energy density. Through threshold warning, it can issue warning signals in time before the occurrence of separated seam water disasters, thus winning precious time for personnel evacuation and disaster prevention and control. It improves the mine's ability to respond to water disasters and minimizes casualties and property losses to the greatest extent.

[0044] (3) The method of the present invention can control the separated seam water pressure in real time. When it is monitored that the separated seam water level reaches the warning water level, the water pump is automatically started to drain water, reduce the water level, prevent the outburst of separated seam water, and achieve the integration of monitoring, warning and control.

[0045] (4) The present invention can effectively reduce the drainage volume of separated seam water in the mine, protect underground water resources and the environment, and improve the economic benefits of the mine. Description of the Drawings

[0046] Figure 1 It is a schematic diagram of the force on the floor water-resisting layer of separated seam water;

[0047] Figure 2 It is the layout diagram of the water level monitoring borehole and the drainage borehole in Embodiment 1, and the arrow in the figure indicates the working face trend;

[0048] Figure 3 It is the cross-sectional view of the monitoring borehole.

[0049] The reference numerals in the drawings denote:

[0050] 1 - monitoring borehole, 2 - drainage borehole, 3 - water pump, 4 - separated seam water, 5 - water pressure sensor.

[0051] The present invention will be further described in detail below with reference to the drawings and specific embodiments. Specific Embodiments

[0052] To make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described below with reference to the drawings.

[0053] The following specific embodiments of the present invention are given. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solution of the present application fall within the protection scope of the present invention.

[0054] The terms "upper", "lower", "front", "rear", "top", "bottom", etc. used in the present invention to indicate the orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "Inner" and "outer" refer to the inside and outside of the corresponding component contour, and the above terms should not be construed as limiting the present invention.

[0055] Unless otherwise specified, the components used in the present invention, such as water pressure sensors, microseismic sensors, and water pumps, are commercially available.

[0056] The following explains the technical terms involved in this application:

[0057] Water-conducting fissure zone: The fissure area that can conduct water formed by the rupture of overlying strata due to mining activities. Its height is crucial for water control in mines.

[0058] High-level separated water: It refers to the separated water formed by the uneven settlement of strata above the water-conducting fissure zone of the coal seam roof.

[0059] Embodiment 1

[0060] Following the above technical solution, this embodiment provides a method for monitoring and drainage control of high-level separated water based on rock mass hydraulics, including the following steps:

[0061] Step 1: Determine the roof rock stratum structure, rock mechanical properties, and key stratum theory of the coal mining face according to the preliminary exploration results, and determine the development location of separated water;

[0062] Specifically, Step 1 includes the following sub-steps:

[0063] Step 1.1: Determine the roof rock stratum structure, rock mechanical properties, and key stratum theory of the coal mining face according to the preliminary exploration results, and determine the key stratum;

[0064] Among them, the roof rock stratum structure and rock mechanical properties can be determined based on the data obtained from the preliminary exploration. The key stratum theory is an existing theory, and the key stratum can be determined based on this theory.

[0065] Step 1.2: Use the existing modeling method to construct a geological model of the coal seam to be mined, input the rock stratum mechanical parameters and mining parameters determined according to the preliminary exploration into the constructed geological model, and then use the geological model to complete the simulation of the mining process to obtain the simulated results of rock stratum displacement and stress change during the mining process;

[0066] In this embodiment, the FLAC3D software is used to construct a geological model of the coal seam to be mined, and after inputting the parameters, the displacement and stress distribution of the rock stratum during the mining of the coal seam are simulated.

[0067] Step 1.3: Determine the development location of separated water according to the obtained simulated results of rock stratum displacement and stress change.

[0068] Step 2: Construct monitoring borehole 1 and drainage borehole 2 for communicating with separated water on the ground above the determined development location of separated water. The layout positions of monitoring borehole 1 and drainage borehole 2 are as shown in Figure 2 and Figure 3As shown, the development of separated seam water can be judged by injecting water into the borehole and recording the water injection pressure and water injection volume. If a sudden increase in the water injection volume and a sudden drop in the water injection pressure are monitored during water injection within a certain depth range, it indicates that there is a separated seam space at this position. When it is determined through monitoring borehole 1 that there is accumulated separated seam water, drainage can be carried out through drainage borehole 2.

[0069] Step 3: Install a water pressure sensor 5 at the bottom of monitoring borehole 1, and install a water pump 3 in drainage borehole 2.

[0070] Among them, the water pressure sensor 5 is used to monitor the water level change for a long time. If a sudden abnormal increase in the water level is monitored, it indicates that there is accumulated separated seam water, and the water pump 3 installed in drainage borehole 2 can be used for drainage.

[0071] Preferably, monitoring borehole 1 is arranged at the center of the square when the working face is mined, and the distance between the bottom hole position of monitoring borehole 1 and the floor of the separated seam water is 1 - 1.5 m.

[0072] According to the test experience of the development height of the water-conducting fissure zone, when the working face is mined in a square, due to the control effect of the key stratum, the stress concentration and expansion of the overlying strata are intensified, and the movement and deformation of the overlying strata are intensified, resulting in the expansion and connection of mining-induced fissures in a larger range, forming a relatively continuous water-conducting fissure network, making the development height of the water-conducting fissure zone reach the maximum value, and the bending deformation of the upper part reach the maximum value. At this time, the separated seam space in the overlying strata is the largest, the recharge channel of the overlying aquifer is unobstructed, and the separated seam water pressure basically reaches the maximum value. At this time, the separated seam water develops most fully. Therefore, the monitoring borehole 1 is arranged at the center position of the square when the working face is mined in a square, that is, the center position of the square.

[0073] Step 4: Arrange multiple microseismic sensors at intervals in the roof rock strata of the upper gate roadway and the lower gate roadway of the mining working face respectively; determine the development height of the water-conducting fissure zone according to the microseismic signals collected by the microseismic sensors.

[0074] Preferably, the setting interval of the microseismic sensors is 100 m, and this setting interval can ensure the balance between the monitoring coverage and accuracy.

[0075] The change process of the caving zone rock strata is "fissure generation - expansion - rock stratum fracture - fragmentation and caving". The microseismic events are dense and concentrated in layers, with obvious layered characteristics. The low-position rock strata in the caving zone are strongly damaged, and the concentration of microseismic events is high. The caving occurs layer by layer from bottom to top, and the concentration of microseismic events in the high-position rock strata is lower. The microseismic sensors capture the microseismic signals generated by the rock mass rupture in real time, and then according to the collected microseismic signals, the existing density clustering algorithm is used to determine the rupture position, strength and time of the rock mass during the formation and migration of the separated seam water, and then the development height of the water-conducting fissure zone can be determined.

[0076] Step 5. Determine the thickness of the water-resisting layer for separated seam water according to the development height of the water-conducting fissure zone;

[0077] Specifically, the thickness of the water-resisting layer for separated seam water is determined by the following formula:

[0078] h = h1 - h2

[0079] In the formula:

[0080] h is the thickness of the water-resisting layer for separated seam water, with the unit of m;

[0081] h1 is the distance between the separated seam water and the top surface of the coal seam, with the unit of m;

[0082] h2 is the development height of the water-conducting fissure zone, with the unit of m.

[0083] Step 6. Determine the warning water head for separated seam water according to the thickness of the water-resisting layer for separated seam water; determine the warning water level according to the warning water head for separated seam water and the floor elevation of the separated seam water obtained from the previous exploration, and set the determined warning water level for separated seam water as the warning water level;

[0084] As Figure 1 shown, when the water pressure of the separated seam water acts on the water-resisting layer, the water-resisting layer will bend, and tensile stress will be generated inside the water-resisting layer. When the tensile stress in the water-resisting layer is greater than the tensile strength σ T of the water-resisting layer, the water-resisting layer for separated seam water will be damaged and water inrush will occur.

[0085] Preferably, the warning water head for separated seam water is determined by the following formula:

[0086]

[0087] In the formula:

[0088] H is the warning water head for separated seam water, with the unit of MPa;

[0089] h is the thickness of the water-resisting layer for separated seam water, with the unit of m;

[0090] σ T is the tensile strength of the water-resisting layer, with the unit of MPa; it is measured through rock mechanics experiments after sampling the water-resisting layer.

[0091] γ w is the specific gravity of water, with the unit of kg / m 3 ;

[0092] L is the inclined length of the working face, with the unit of m;

[0093] K is the safety factor, and its value is 1.2. For safety, the safety factor is added, and K is an empirical value obtained based on the statistical results of water inrush cases.

[0094] It can be seen from the above formula that the ultimate water head of the separated water is directly proportional to the tensile strength of the ultimate water-resisting layer, directly proportional to the square of the thickness of the water-resisting layer, and inversely proportional to the square of the inclined length of the working face. This is very important for judging the safety of the separated water.

[0095] Preferably, the warning water level is determined according to the warning water head of the separated water and the floor elevation of the separated water obtained from the previous exploration, and is realized through the following formula:

[0096] H 水位 = H + H0

[0097] Wherein,

[0098] H 水位 is the warning water level, with the unit of m;

[0099] H is the warning water head of the separated water, with the unit of m;

[0100] H0 is the floor elevation of the separated water, with the unit of m.

[0101] Step 7: The water level data in the monitoring borehole 1 is collected in real time through the water pressure sensor 5 to obtain the real-time water level. When the real-time water head exceeds the warning water level, the water pump 3 is started to pump the separated water to realize the control of the separated water level.

[0102] The method of the present invention dynamically correlates the microseismic signal with the water level data. The microseismic signal captures the dynamics of the water-conducting fissures, and the water pressure sensor monitors the water level in real time. By using microseismic monitoring and separated water level monitoring, information on the high-level separated water is obtained from different angles, effectively improving the monitoring accuracy; by using the method of the present invention, the formation, migration and water pressure change of the separated water can be found in time, providing reliable data support for subsequent control and warning.

[0103] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A monitoring and drainage control method for high-level separated water based on rock mass hydraulics, characterized in that, It includes the following steps: Step 1: Determine the roof rock stratum structure, rock mechanical properties and key stratum theory of the coal mining face according to the preliminary exploration results, and determine the location where separated seam water develops; Step 2: Construct monitoring boreholes and drainage boreholes on the ground above the determined location where separated seam water develops to communicate with the separated seam water; Step 3: Place a water pressure sensor at the bottom inside the monitoring borehole; install a water pump inside the drainage borehole; Step 4: Arrange multiple microseismic sensors at intervals in the roof rock strata of the upper gate roadway and the lower gate roadway of the coal mining face respectively; determine the development height of the water-conducting fissure zone according to the microseismic signals collected by the microseismic sensors; Step 5: Determine the thickness of the separated seam water aquitard according to the development height of the water-conducting fissure zone; Step 6: Determine the warning water head of the separated seam water according to the thickness of the separated seam water aquitard; determine the warning water level according to the warning water head of the separated seam water and the separated seam water floor elevation obtained from the preliminary exploration, and set the determined separated seam water warning water level as the early warning water level; Step 7: Real-time collect the water level data in the monitoring borehole through the water pressure sensor to obtain the real-time water level. When the real-time water head exceeds the early warning water level, start the water pump to pump out the separated seam water to realize the control of the separated seam water level.

2. The high-level separated seam water monitoring and drainage control method based on rock mass hydraulics according to claim 1, characterized in that, The specific steps of Step 1 include the following sub-steps: Step 1.1: Determine the roof rock stratum structure, rock mechanical properties and key stratum theory of the coal mining face according to the preliminary exploration results, and determine the key stratum; Step 1.2: Establish a geological model of the coal seam to be mined and complete the simulation of the mining process to obtain the simulation results of the rock stratum displacement and stress change during the mining process; Step 1.3: Determine the location where separated seam water develops according to the obtained simulation results of the rock stratum displacement and stress change.

3. The high-level separated seam water monitoring and drainage control method based on rock mass hydraulics according to claim 1, characterized in that The monitoring boreholes are arranged at the center of the square of the coal face during mining, and the distance between the end hole position and the separated seam water floor is 1 - 1.5 m.

4. The high-level separated water monitoring and drainage control method based on rock mass hydrodynamics according to claim 1, characterized in that, The interval set in Step 4 is 100 m.

5. The high-level separated seam water monitoring and drainage control method based on rock mass hydraulics according to claim 1, characterized in that, In Step 5, the thickness of the separated seam water aquitard is determined by the following formula: h = h1 - h2 In the formula: h is the thickness of the separated seam water aquitard, with the unit of m; h1 is the distance between the separated seam water and the top surface of the coal seam, with the unit of m; h2 is the development height of the water-conducting fissure zone, with the unit of m.

6. The high-level separated water monitoring and drainage control method based on rock mass hydraulics according to claim 1, characterized in that The warning water head of the separated seam water in Step 6 is determined by the following formula: In the formula: H is the warning water head of the separated seam water, with the unit of MPa; h is the thickness of the separated seam water aquitard, with the unit of m; σ T is the tensile strength of the aquitard, with the unit of MPa; γ w is the specific gravity of water, with the unit of kg / m 3 ; L is the inclined length of the working face, with the unit of m; K is the safety factor.

7. The high-level separated seam water monitoring and drainage control method based on rock mass hydraulics according to claim 1, characterized in that, The determination of the warning water level according to the warning water head of the separated seam water and the separated seam water floor elevation obtained from the preliminary exploration in Step 6 is realized by the following formula: H 水位 = H + H0 Where, H 水位 is the warning water level in m; H is the warning water head of the separated seam water, with the unit of m; H0 is the separated seam water floor elevation, with the unit of m.

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