A method for determining the boundary of an empty area encountered by a tunneling face

Abstract

The application discloses a kind of determination methods of encountering empty area boundary in heading face, comprising: using transient electromagnetic method to explore the distribution form of advance 30m goaf;According to the exploration result, the drilling path is preferably arranged;Drill hole is arranged, drill to goaf, stop drilling when goaf is found, and retreat;High-precision scanning probe is extended into the interior of empty area through drill hole to scan and identify, and the boundary of goaf is obtained.The application adopts geophysical prospecting+drilling method, integrates the respective advantages of both, provides guidance for the drilling path of drilling, avoids the occurrence of sticking and dropping accidents when drilling to rock broken area;At the same time, the drilling target area point is preferably selected by geophysical prospecting and drilling, and the exploration efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of residual coal resource recovery in goaf areas, and particularly relates to a method for determining the boundary of goaf areas encountered in tunneling faces. Background Technology

[0002] Goaf areas are underground "cavities" created by human excavation during mining activities. The existence of goaf areas poses significant safety challenges to various engineering construction and operation processes. During mine consolidation, some small mines that have been consolidated have not fully exploited their resources due to outdated mining technology, resulting in many difficult-to-explore goaf areas. To recover the remaining resources in these goaf areas, it is necessary to excavate tunnels and conduct exploration during the excavation process.

[0003] Existing methods for detecting goaf areas mainly include three types. The first is using large geological testing equipment. However, because the location of goaf areas is unpredictable and the equipment is very heavy, deploying such equipment within the goaf area can easily trigger geological collapses, posing a risk of workers and equipment falling into the goaf. The second method is establishing a ground pressure monitoring network for long-term effective monitoring. However, establishing such a network typically takes too long, and because goaf areas vary in size, the network cannot accurately monitor smaller goaf areas, resulting in low accuracy. The third method is geophysical methods, which indirectly measure goaf areas by measuring the distribution of stratigraphic resistivity (high-density resistivity method) or dielectric constant (ground-based radar). The resistivity method relies on volumetric effects and suffers from low spatial resolution, while radar has a shallow detection depth, further contributing to low accuracy. Summary of the Invention

[0004] Based on the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method for determining the boundary of the void area in a tunneling face, which is simple, efficient and accurate, and can accurately determine the boundary of the void area in various complex tunneling and working face tunneling processes.

[0005] To solve the above-mentioned technical problems, the present invention provides a method for determining the boundary of a void area in a tunneling face, comprising the following steps:

[0006] S1. Use transient electromagnetic method to investigate the distribution pattern of the goaf 30m ahead;

[0007] S2. Select the drilling path based on the exploration results; arrange the boreholes, drill into the goaf, stop drilling when the goaf is discovered, and retreat;

[0008] S3. Insert a high-precision scanning probe into the goaf through a borehole to scan and identify the boundary of the goaf.

[0009] Optionally, step S1 includes: the transient electromagnetic exploration method uses a center loop device, and the detection points are arranged at the working face.

[0010] Furthermore, the transient electromagnetic method was used for advance exploration, with three survey lines laid out: 30° above the roof of the roadway, 30° below the floor of the roadway along the same course.

[0011] Furthermore, 11 physical measuring points were arranged on the roof, the roadway along the same level, and the floor, with the angles extending from 50° to 50° to the left and 10° to the right. A total of 33 data collection points were completed.

[0012] Furthermore, the area being probed is a fan-shaped region, and each physical measuring point has data for three time periods: early, middle, and late.

[0013] Optionally, in step S2, the drilling speed, water output, and gas concentration are used to determine whether the goaf has been reached, thereby delineating the boundary of the goaf.

[0014] Furthermore, the boundary of the goaf is determined within the geophysical exploration range by drilling exploration. During the drilling process, if a fractured area of ​​the surrounding rock is encountered, drilling continues until the goaf is discovered, at which point drilling stops and the drill bit is withdrawn.

[0015] Furthermore, the high-precision scanning probe is connected to the rod body via a rotating buckle; the high-precision scanning probe is provided with a protective cover on the outside, and the inner side of the protective cover is provided with first, second, third and fourth lenses.

[0016] Furthermore, a three-dimensional model is constructed using three-dimensional laser scanning to estimate the volume of residual coal in the goaf and determine the range and boundaries of the goaf.

[0017] The present invention provides a method for determining the boundary of a goaf through a combination of advanced drilling and geophysical exploration. It employs the mine transient electromagnetic method to advance the exploration of the goaf distribution within 30 meters of the tunneling face. Survey lines are laid out at 30° to the roof, along the direction of the bedding roadway, and at 30° below the roadway floor. Eleven physical measuring points are then placed at 50° to the left and right, spaced 10° apart, forming a fan-shaped area. The geoelectric information obtained by the mine transient electromagnetic method is extracted and qualitatively analyzed with the geological data of the tunneling face to obtain the geological structure of the tunneling face. This allows for the deduction of the approximate shape of the goaf and the provision of the optimal drilling path. Additionally, it can also obtain the complete information about the tunneled coal and rock mass. The geological structure is obtained using the transient electromagnetic method. A suitable drilling angle is selected to avoid fractured rock areas and prevent drill bit jamming or falling out. The drilling speed, water output, and gas concentration determine whether the goaf boundary has been reached. When a goaf is detected, drilling is stopped and the drill bit is withdrawn. A high-precision scanning probe, connected to the rod by a rotating clip, is inserted into the borehole to scan the interior of the goaf. The probe is protected by a cover, and the inner side of the cover contains first, second, third, and fourth lenses. Combined with optimized laser emission, this effectively eliminates aberrations at the edges, improving the accuracy of the high-precision scanning probe. The distance and relative position are calculated using the round-trip time of the pulsed laser over the measured distance and the emission angle of the pulsed laser. A three-dimensional map of the goaf is created using a special data collection and imaging system to estimate the residual coal volume and determine the goaf's extent and boundaries.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, the following detailed description is provided in conjunction with preferred embodiments and accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0020] Figure 1 This is a flowchart illustrating the method for determining the boundary of the void area in the tunneling face according to the present invention.

[0021] Figure 2 This is a schematic diagram of the method for determining the boundary of the void area in the working face.

[0022] Among them, 1-excavation roadway, 2-geophysical exploration equipment, 3-optimal drilling path, 4-front void, 5-high-precision scanning probe, 6-geophysical exploration range, and 7-front fractured surrounding rock zone. Detailed Implementation

[0023] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this specification. These embodiments illustrate the principles of the invention, and other aspects, features, and advantages of the invention will become apparent from this detailed description. In the accompanying drawings, the same or similar parts in different figures are indicated by the same reference numerals.

[0024] like Figure 1 As shown, the method for determining the boundary of the void area in the tunneling face according to the present invention includes the following steps:

[0025] Step 1: During the tunnel excavation process using the transient electromagnetic method in the mine, test the distribution of the goaf within a distance of 30m ahead. Detection coils are placed directly in front of the working face. Survey lines are arranged at 30° on the roof in front of the tunnel, 30° in the direction of the tunnel excavation along the bedding plane, and 30° below the tunnel floor. Then, 11 physical measuring points are arranged on the roof, the tunnel along the bedding plane, and the floor, at 50° to the left and 50° to the right, with one physical measuring point every 10°, forming a fan-shaped area.

[0026] This invention utilizes the transient electromagnetic method in mines, a time-domain artificial electromagnetic detection method based on electromagnetic induction. The principle involves using an ungrounded TX (magnetic source) to emit a pulsed magnetic field, also known as the primary magnetic field, towards the working face. At the moment the primary field closes, the induced eddy currents generated in the highly conductive ore body are time-decreasing eddy current fields, which can generate a time-varying induced electromagnetic field, also known as the secondary field. The decay process is generally divided into early, middle, and late stages, with a total of 33 data points collected. The time-varying induced electromagnetic field can reflect various geoelectric information, such as the shape, size, location, and conductivity of the highly conductive ore body. The response field within the pulsed magnetic field interval is observed using a receiving coil RX. This corresponding information is extracted and qualitatively analyzed with the geological data of the tunneling face to obtain the geological structure of the tunneling face ahead, thereby deducing the approximate morphology of the goaf and providing the optimal drilling path. In complex geological conditions within mines, it is necessary to collect and investigate all known geological data in the tunneling face area to better understand the geological characteristics of the goaf, thereby determining the extent of the fractured surrounding rock zone and the approximate morphology of the goaf.

[0027] For example, water, as a conductor, often threatens the safe production of coal mines. Therefore, transient electromagnetic methods are often used in the hydrogeological exploration of coal mines. They can also be used to detect whether there are water areas in the goaf, thus avoiding accidents during tunneling.

[0028] This invention qualitatively analyzes the extracted information with the geological data of the tunneling face to obtain the geological structure of the tunneling face ahead, thereby deducing the approximate shape of the goaf and providing the optimal drilling path.

[0029] Step 2: Obtain the geological structure of the working face using the transient electromagnetic method, determine the integrity of the coal and rock mass ahead, and select an appropriate drilling angle based on the actual conditions of the mine to avoid the rock in the fractured area and prevent drilling accidents such as stuck drill or falling drill from occurring.

[0030] Step 3: Based on Step 2, drill holes are arranged in the optimal drilling area. Drilling can be carried out by geological drilling rig or by manual drilling. The drilling speed, water output and gas concentration are used to determine whether the boundary of the goaf is reached. When the goaf is found, drilling is stopped and the drill bit is withdrawn.

[0031] Step 4: Insert a high-precision scanning probe into the borehole drilled in Step 3 to scan the interior of the goaf. The high-precision scanning probe is connected to the rod body via a rotating buckle, facilitating installation and disassembly and improving work efficiency. Additionally, the high-precision scanning probe is equipped with a protective cover, and inside the cover are first, second, third, and fourth lenses. The coordinated use of these lenses optimizes the emitted laser light, effectively eliminating aberrations at the edges and improving the accuracy of the high-precision scanning probe. The distance and relative position are calculated using the round-trip time of the pulsed laser over the measured distance and the emission angle of the pulsed laser. A three-dimensional map of the goaf is then created using a special data collection and imaging system to estimate the volume of residual coal in the goaf and determine its extent and boundaries.

[0032] When planning boreholes, exploration can be conducted using geological drilling rigs or by manual drilling.

[0033] The detection coil is placed directly in front of the working face. Survey lines are arranged at 30° on the roof in front of the roadway, 30° in the direction of the roadway excavation and 30° below the roadway floor. Then, 11 physical measuring points are arranged on the roof, the roadway and the floor respectively, at 50° to the left and 50° to the right, with one physical measuring point every 10°, forming a fan-shaped area.

[0034] like Figure 2 As shown, geophysical exploration equipment 2 is deployed 30m ahead of tunnel 1. The exploration range using the mine transient electromagnetic method is defined as geophysical exploration range 6. Based on the information extracted from the exploration and the geological data of the tunneling face, a qualitative analysis is performed to obtain the geological structure of the tunneling face ahead. This allows for the deduction of the approximate shape of the goaf and provides the optimal drilling path 3 and the fractured surrounding rock zone 7 ahead. Drill holes are arranged using geological drilling rigs or manual drilling methods. High-precision scanning probes 5 are inserted into the drill holes. The distance and relative position are calculated using the time it takes for the pulsed laser to travel back and forth over the measured distance and the emission angle of the pulsed laser. A three-dimensional map of the goaf is established through a special data collection and imaging system to estimate the volume of residual coal and water accumulation in the goaf, thereby determining the range and boundary of the goaf 4 ahead.

[0035] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for determining the boundary of an empty area in a tunneling working face, characterized in that, The method comprises the following steps: S1, using transient electromagnetic method to explore the distribution of goaf 30m in advance; S2, according to the exploration results, the drilling path is selected; the drilling is arranged, drilling to the goaf, stopping drilling when the goaf is found, and withdrawing; S3, the high-precision scanning probe is extended into the goaf through the drilling to scan and identify, and the boundary of the goaf is obtained; The step S1 comprises: the transient electromagnetic method exploration adopts a central loop device, and the detection points are arranged at the face head; The transient electromagnetic method advanced exploration arranges three measuring lines on the roof 30° in front of the roadway, along the direction of the roadway and 30° below the floor in front of the roadway; The roof, the along-the-layer roadway and the floor are respectively arranged with 11 physical measuring points, the angle is expanded to left 50° to right 50°, one physical measuring point is arranged at an angle interval of 10°, and 33 data acquisition points are completed in total; the detected range is a fan-shaped area, and each physical measuring point has data of three time periods of early, middle and late; In the step S2, whether the goaf is reached is determined according to the drilling speed, water yield and gas concentration, so as to delineate the boundary of the goaf; the boundary of the goaf is determined in the geophysical prospecting range through the drilling exploration mode; in the drilling process, when the front surrounding rock broken zone is encountered, the drilling is continued, until the goaf is found, the drilling is stopped, and the drill bit is withdrawn.

2. The method of claim 1, wherein, The high-precision scanning probe is connected with the rod body through a rotating buckle; a protective cover is arranged outside the high-precision scanning probe, and the first, second, third and fourth lenses are arranged inside the protective cover.

3. The method of claim 2, wherein, A three-dimensional model is constructed through three-dimensional laser scanning, the residual coal volume of the goaf is estimated, and the range and boundary of the goaf are determined.

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