Experimental device for detecting response characteristics of high-dip-angle coal seam through intermediate gradient method

Abstract

The utility model discloses an experimental device for detecting response characteristics of a high dip angle coal seam by an intermediate gradient method, which comprises a digital bridge, an opening box, a universal meter, a lead, electrode bars and a simulated stratum, the opening box is provided with a bayonet, the electrode bars comprise a power supply electrode A, a power supply electrode B, a measuring electrode M and a measuring electrode N, and the simulated stratum comprises loam a, sandy soil b, a wood plate c and clayey soil d; the experimental method of the utility model comprises the following steps: generating an underground artificial current field through a digital bridge, measuring current values and voltage values of measuring points of a measuring line by using an intermediate gradient method, obtaining an apparent resistivity value according to a formula, then drawing, and exploring the influence of different factors on an apparent resistivity curve of the device; the device is simple, cheap, safe and efficient, and is convenient for students to operate, understand, apply and popularize; according to the utility model, electrode spacing, earth surface soil thickness and coal seam inclination angle can be measured, coal seam thickness can be used for exploration of response characteristics of a high inclination angle coal seam detected by a middle gradient method, and the operability is strong.

Description

Technical Field

[0001] The utility model relates to the field of teaching experiments in geophysical exploration, in particular to an experimental device for detecting response characteristics of high-inclination coal seams using an intermediate gradient method. Background Art

[0002] Electrical prospecting, a method that uses differences in apparent resistivity to distinguish lithology and structures, is the most widely used method in geophysical exploration. Based on the exploration method and data acquisition method, it can be divided into electrical profiling and electrical sounding.

[0003] The key to electrical exploration lies in the measurement and calculation of formation apparent resistivity. The calculation formula is: Where, ρ s is the apparent resistivity of the formation, measured in Ω·m; k is the resistivity coefficient, measured in m; ΔU is the potential difference between points M and N, measured in V; and I is the current between points M and N, measured in A. The potential difference and current between measuring points M and N can be measured using a multifunctional electrical analyzer, while k is a coefficient related to the distance between the four electrodes A, B, M, and N.

[0004] The intermediate gradient method is a commonly used and important method in resistivity profiling. During the measurement, the power supply electrodes A and B are far apart and fixed, while the measuring electrodes M and N are moved point by point along the measuring line within the 1 / 3 section between AB. The apparent resistivity value ρ of each measuring point (the midpoint of MN) is calculated. s , thereby obtaining the variation in apparent resistivity within this range, and understanding the distribution of geological bodies at a certain depth and within a certain range along the survey line. Due to the principle of gradient measurement and the high vertical resolution, this method can more clearly reflect the location and morphology of high-resistance vertical veins.

[0005] Deep in the interior of China, Xinjiang has undergone profound geological evolution, resulting in a complex geological structure and rich mineral resources. In particular, the complex, steep-angle geology of the Xinjiang Basin has created coal seams with dips greater than 30° (coal seams with dips between 35° and 55° are generally considered steep-angle reservoirs). In steep-angle coal seams, forces acting along the bedding plane of the coal or rock formation increase, complicating surrounding rock stress and rock migration, impacting mining safety and coal extraction. Therefore, the application of the intermediate gradient method to explore high-angle coal seams is essential.

[0006] In geophysical electrical prospecting teaching, students lack access to specialized equipment used by production units. Furthermore, actual exploration is affected by uncontrolled factors such as terrain slope, surface soil cover, and complex surrounding rock. This makes it difficult for students to understand the principles of the intermediate gradient method for detecting high-angle coal seams, calculate apparent resistivity, and explore influencing factors. Therefore, it is urgent to develop an experimental device for detecting the response characteristics of high-angle coal seams using the intermediate gradient method. This device can help students understand the principles, accurately calculate apparent resistivity, and explore influencing factors, thereby guiding teaching. Utility Model Content

[0007] The purpose of the utility model is to enable students to understand the actual process of detecting high-angle coal seams using the intermediate gradient method in a simple, safe and efficient way, so as to promote teaching.

[0008] The technical solution of the utility model is: an experimental device for detecting the response characteristics of high-angle coal seams using an intermediate gradient method, which is composed of a digital bridge, an open box, a multimeter, a wire, an electrode rod, and a simulated stratum. The open box is provided with a bayonet, the electrode rod includes a power supply electrode A, a power supply electrode B, a measuring electrode M, and a measuring electrode N, and the simulated stratum includes loam a, sandy soil b, a wooden board c, and clay soil d.

[0009] The open box is assembled and spliced ​​by bayonet joints, and the loam a, sandy soil b, wooden board c, and clay soil d filled inside it form a simulated stratum; the power supply electrode A and the power supply electrode B are connected to the positive and negative poles of the digital bridge through wires; the measuring electrode M and the measuring electrode N are connected to the positive and negative poles of the multimeter through wires.

[0010] Preferably, the digital bridge model is TH6213, which is a DC safety power supply and can manually set the current and voltage values ​​to provide a stable artificial current field.

[0011] Preferably, the open box is made of acrylic material, is transparent as a whole, has a length, width and height of 0.5m each, is provided with a bayonet on the inside to assemble and fix the box, and is marked on the outside with scales from bottom to top and from left to right to read the simulated formation thickness and the relative position of the electrode rods.

[0012] Preferably, the multimeter model is UT18BMAX, the current range accuracy is ±(range 1.2%+3mA), and the voltage range accuracy is ±(range 0.4%+3mV), ensuring that the error of apparent resistivity is within a reasonable range.

[0013] Preferably, the electrode rods include a power supply electrode A, a power supply electrode B, a measuring electrode M, and a measuring electrode N, all of which are made of graphite and have excellent electrical conductivity to ensure the implementation of the experiment.

[0014] Preferably, the simulated strata includes loam a, sandy soil b, wooden board c, and clay d; loam a simulates surface soil, sandy soil b and clay d simulate surrounding rock, and wooden board c simulates coal seam; there are 4 pieces with a length of 0.5m, a width of 0.35m, and thicknesses of 1cm, 2.5cm, 5cm, and 10cm respectively.

[0015] Preferably, during the implementation process, the electrode spacing MN, loam a thickness, wooden board c inclination, and wooden board c thickness can be measured to explore the response characteristics of different factors to the intermediate gradient method for detecting high-angle coal seams.

[0016] The beneficial effects of the present invention are:

[0017] (1) The device of the utility model is simple, cheap, safe and efficient, which makes it easier for students to understand the process of detecting high-angle coal seams using the intermediate gradient method and is also helpful for its implementation and promotion.

[0018] (2) The implementation of this utility model: hands-on operation, personal calculation of apparent resistivity and drawing, stimulates learning interest and has strong teaching practice value; at the same time, it can carry out research on the response characteristics of measuring electrode spacing, surface soil thickness, coal seam inclination, and coal seam thickness to the intermediate gradient method for detecting high-inclination coal seams, guide students to think deeply, and cultivate scientific research thinking.

[0019] (3) The experimental method of the present invention is as follows: an underground artificial current field is generated by a digital bridge, the current value and voltage value of the measuring point of the measuring line are measured using the intermediate gradient method, the apparent resistivity value is obtained according to the formula, and then a graph is drawn to explore the influence of different factors on the apparent resistivity curve of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a top view of the device of the present utility model.

[0021] Figure 2 This is a front view of the open box of the present utility model.

[0022] Figure 3 This is a measurement point record table for an embodiment of the present utility model.

[0023] Figure 1: 1-digital bridge; 2-open box; 3-multimeter; 4-wire; 5-bayonet; 6-electrode rod: power supply electrode A, power supply electrode B, measuring electrode M, measuring electrode N; 7-simulated stratum: loam a, sandy soil b, wooden board c, clay soil d. DETAILED DESCRIPTION

[0024] The following is a further description of the embodiments of the present invention in conjunction with the accompanying drawings, but is not intended to limit the present invention.

[0025] Before describing the specific embodiments of the present invention, in order to make the solution of the present invention clearer and more complete, the devices appearing in the present invention are first described:

[0026] Digital bridge: Model TH6213, a DC safety power supply, and the current and voltage values ​​can be manually set to provide a stable artificial current field.

[0027] Open box: Made of acrylic, transparent as a whole, 0.5m in length, width and height, with a bayonet on the inside to assemble and fix the box, and a scale marked from bottom to top and from left to right on the outside to read the simulated stratum thickness and the relative position of the electrode rods.

[0028] Multimeter: Model UT18BMAX, current range accuracy is ±(range 1.2%+3mA), voltage range accuracy is ±(range 0.4%+3mV), ensuring that the error of apparent resistivity is within a reasonable range.

[0029] Electrode rods: including power supply electrode A, power supply electrode B, measuring electrode M, and measuring electrode N, all made of graphite with excellent conductivity to ensure the implementation of the experiment.

[0030] Simulated strata: including loam a, sandy soil b, wooden board c, and clay soil d; loam a simulates surface soil, sandy soil b and clay soil d simulate surrounding rock, and wooden board c simulates coal seam; there are four pieces with a length of 0.5m, a width of 0.35m, and thicknesses of 1cm, 2.5cm, 5cm, and 10cm respectively; the resistivity under normal conditions is: wooden board c>sandy soil b>loam a>clay soil d.

[0031] As shown in the figure, this utility model patent provides an experimental device for detecting the response characteristics of high-angle coal seams using the intermediate gradient method. It consists of a digital bridge, an open box, a multimeter, a wire, an electrode rod, and a simulated stratum. The open box is provided with a bayonet. The electrode rod includes a power supply electrode A, a power supply electrode B, a measuring electrode M, and a measuring electrode N. The simulated stratum includes loam a, sandy soil b, wooden board c, and clay soil d.

[0032] The open box is assembled and spliced ​​by bayonet joints, and the loam a, sandy soil b, wooden board c, and clay soil d filled inside it form a simulated stratum; the power supply electrode A and the power supply electrode B are connected to the positive and negative poles of the digital bridge through wires; the measuring electrode M and the measuring electrode N are connected to the positive and negative poles of the multimeter through wires.

[0033] Steps:

[0034] (1) Align the bayonet joints of the acrylic plate with each other on the laboratory table and assemble the open box.

[0035] (2) Constructing a simulated stratum: Place a 2.5 cm thick wooden board c upright, and fill the two separated areas with sandy soil b and clay soil d; when the sandy soil b and clay soil d reach the same level as the top of the wooden board, squeeze them tightly with a geological hammer or other tools; then fill the loam a to 45 cm from the opening box (i.e., the initial simulated coal seam has an inclination of 90° and a thickness of 2.5 cm, and the initial simulated surface soil is 10 cm thick).

[0036] (3) Laying out electrodes: Insert the power supply electrode A, measuring electrode M, measuring electrode N, and power supply electrode B vertically and at equal depths in a straight line from left to right on the loam a. The horizontal positions are: 4 cm, 18 cm, 20 cm, and 46 cm respectively (i.e., the measuring line range is 18 cm-32 cm, the power supply electrode distance AB is 42 cm, and the initial measuring electrode spacing MN is 2 cm).

[0037] (4) Use wires to connect the electrode rods to the digital bridge and multimeter.

[0038] (5) Measure and record data: Turn on the digital bridge, output DC power at both ends of the power supply electrode A and the power supply electrode B to establish an artificial current field; turn on the multimeter, switch the gear to the current gear, measure the current at the midpoint between the measuring electrode M and the measuring electrode N, and record the data; switch the gear to the voltage gear, measure the voltage at the midpoint between the measuring electrode M and the measuring electrode N, and record the data.

[0039] (6) Measure each point on the measuring line: Maintain a 2 cm distance between the measuring electrodes MN, move the measuring electrodes M and N horizontally to the right, record the data of each measuring point, and stop measuring before the position of the measuring electrode N exceeds 32 cm.

[0040] (7) Calculate the apparent resistivity based on the data and formula, and draw a curve showing the change of apparent resistivity with the coordinate position.

[0041] (8) The first group: Adjust the measuring electrode spacing MN to 1 cm, 3 cm, and 4 cm, repeat the process (1)-(6), record the data, draw the curve, and explore the response characteristics of the measuring electrode spacing to the intermediate gradient method for detecting high-angle coal seams.

[0042] (9) Group 2: Adjust the thickness of loam a to 12 cm, 8 cm, and 6 cm, restore the electrode spacing to 2 cm, repeat the process (1)-(6), record the data, draw the curve, and explore the response characteristics of surface soil thickness to the detection of high-angle coal seams using the intermediate gradient method.

[0043] (10) The third group: adjust the inclination angle of the wooden board c to 75°, 60°, 45°, and 30°, restore the loam a to 10 cm, repeat the process (1)-(6), record the data, draw the curve, and explore the response characteristics of the coal seam inclination to the detection of high-inclination coal seams using the intermediate gradient method.

[0044] (11) Group 4: Replace the thickness of the wooden board c with 1cm, 5cm, and 10cm, keep the inclination angle at 90°, repeat the process (1)-(6), record the data, draw the curve, and explore the response characteristics of the coal seam thickness to the detection of high-inclination coal seams using the intermediate gradient method.

[0045] The experimental method of the utility model is as follows: an underground artificial current field is generated by a digital bridge, the current value and voltage value of the measuring point of the measuring line are measured using the intermediate gradient method, the apparent resistivity value is obtained according to the formula, and then a graph is drawn to explore the influence of different factors on the apparent resistivity curve of the device.

[0046] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An experimental device for detecting the response characteristics of high-angle coal seams using the intermediate gradient method, characterized by: The device is composed of a digital bridge (1), an open box (2), a multimeter (3), a wire (4), an electrode rod (6), and a simulated stratum (7); the open box (2) is provided with a bayonet (5); the electrode rod includes a power supply electrode A, a power supply electrode B, a measuring electrode M, and a measuring electrode N; and the simulated stratum (7) includes loam a, sandy soil b, a wooden board c, and clay soil d. The open box (2) is assembled and spliced ​​through a bayonet (5), and loam a, sandy soil b, wooden board c, and clay soil d filled inside form a simulated stratum (7); the power supply electrode A and the power supply electrode B are connected to the positive and negative poles of the digital bridge (1) through a wire (4); and the measuring electrode M and the measuring electrode N are connected to the positive and negative poles of the multimeter (3) through a wire (4).

2. The experimental device for detecting the response characteristics of high-angle coal seams using the intermediate gradient method according to claim 1 is characterized by: The digital bridge (1) is a TH6213 model, which is a DC safety power supply and can manually set the current and voltage values.

3. The experimental device for detecting the response characteristics of high-angle coal seams using the intermediate gradient method according to claim 1 is characterized by: The open box (2) is made of acrylic material, is transparent as a whole, has a length, width and height of 0.5m, is provided with a bayonet (5) on the inside, and is marked with scales from bottom to top and from left to right on the outside.

4. The experimental device for detecting the response characteristics of high-angle coal seams using the intermediate gradient method according to claim 1 is characterized by: The wooden board c is used to simulate the coal seam, and has four pieces with a length of 0.5m, a width of 0.35m, and thicknesses of 1cm, 2.5cm, 5cm, and 10cm respectively. During implementation, five angles of 30°, 45°, 60°, 75°, and 90° relative to the bottom of the open box (2) were adjusted for exploration.

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