A study of detection mode of mine radio wave perspective technology
In order to maximize the detection efficiency of mine radio wave perspective, the author studies its various working modes, and obtains the walking distance, total detection time, time utilization rate, walking speed, detectable The formula for calculating the maximum working face length. Based on this, a detection parameter calculation table is formed. For the detection of working faces with different lengths in actual work, a reasonable working mode, launch time and station moving time can be selected according to the calculation results in this table to achieve the maximum detection efficiency.
With the release of the “Thirteenth Five-Year Plan” for the national coal industry, the intensive development of coal has become the general trend. Coal production and development will further concentrate on large coal bases, and the output of large coal bases will account for 10% of the total output.
95% or more, and the number of coal enterprises is less than 3,000, of which the output of large enterprises with a capacity of 50 million tons or more accounts for more than 60% [1]. With the continuous construction of super-large mines with tens of millions of tons, large and super-large coal mining faces continue to emerge. In the face of efficient large-scale mines, traditional mine geophysical methods must adapt to the new situation and improve work efficiency in order to better serve large-scale mines and give full play to the efficiency advantages of large-scale mines.
Mine radio wave perspective technology is the pioneer of mine geophysical exploration in my country. As early as the 1950s, my country's coal mines used it to detect abnormal structures in the working face, especially for the detection of collapsed columns and faults. For a long time, the pit penetration technology has developed steadily, and has become a routine and necessary means for the detection of geological anomalies in mine working faces [2] . The main characteristics of the radio wave perspective instrument are as follows: high detection accuracy, stable performance, and long perspective distance, which can meet the detection requirements of most conventional working faces [3]. However, when faced with a large working surface, some problems are also exposed, such as: the short working time of the instrument, the measurement of a working surface several times, and the heavy work intensity of the surveyors, etc. [4] . This paper studies mine radio wave perspective technology
The parameters of various detection modes of the technique are analyzed, and their applicability to working faces of various lengths is analyzed, so that they can meet the detection needs of large and extra-large coal mining faces.
The absorption of electromagnetic waves by a uniform coal seam in the same working face can be regarded as roughly constant. When there are various geological structures such as faults and collapse columns in the coal seam, its absorption of electromagnetic waves will change greatly. The transmitter emits electromagnetic wave signals in one roadway, and the receiver receives electromagnetic wave signals in the opposite roadway. If there are geological anomalies in the working face, the electromagnetic signals passing through the working face will undergo various changes. The electromagnetic signals of this change Recorded by the receiver to form measurement data. By using the principle of CT imaging and digital imaging processing on the received data, the electromagnetic wave absorption coefficient distribution map of the entire working face can be calculated. Analyzing the figure, the areas where the absorption coefficient in the figure becomes larger or smaller than that of the uniform coal seam should correspond to different geological anomalies[512].
There are generally two working methods of radio wave perspective: synchronous method and fixed-point method. The synchronization method is that the transmitter and the receiver move synchronously and receive one value at a time. This method is simple to operate and low in labor intensity, but the detection effect is poor and has been basically eliminated.
The fixed-point method is that the transmitter is relatively fixed on the transmitting point, and the receiver
Receive point by point along the roadway within a certain range of another roadway, and the observation rays are distributed in a fan shape. When a roadway is detected, the transmitter and receiver exchange roadways until the entire working face is detected (Fig. 1). The fixed-point method collects more data and has better detection effect, so it is widely used at present. According to the number of hosts used for detection, the fixed-point method can be divided into multiple working modes. This paper focuses on "one send and one receive", "one send and two receive", "two send and two receive" and combination modes.
Assume that the length of the working face is L, the distance between transmitting points is d1, and the distance between receiving points is d2. , the sum of the walking distances of each host is W, the launch time of a launch point is t1, and the station moving time
is t2, and the total working time is T (not including preparation time and lane exchange
time), the total working time of hosts A, B, C, and D are TA, TB, TC, TD respectively, Vmax is the maximum speed of human walking, the rated working time of transmitter is F, and the longest working surface can be detected at one time. The length is Lmax.
Generally, when using the fixed-point method, in order not to leave detection blind spots, it is necessary to
To ensure 100% coverage of the detection rays (Figure 2), that is, to satisfy
Figure 2 Ray coverage
Figure 3 "Send-to-receive" schematic diagram
machine. The working mode of the transmitter remains the same as the "one send, one receive" mode, while the receiving lane is changed to work with two receivers. "One send and two receive" can be divided into "interval" method and "synchronous" method.
d - (n - 1) d2 ≤ 0⇒d ≤ (n - 1) d2 ,
As shown in Figure 4, let the transmitter be A, the receivers be B and
Generally take d1
= (n-1)d2.
So this paper assumes that d1
= (n-1) d2 ,
c. First, A transmits at transmission point 1, B receives data normally, and C
Wait at the starting position of the receiving segment corresponding to the No. 2 transmitting point. Wait for the 1st issue
And the receiving section is symmetrical.
The "one send one receive" working mode is the most commonly used working mode. Let A be the transmitter and B be the receiver. A transmits at each transmitting point in turn, and B receives data at the corresponding position. After completion, A and B exchange roadways, repeat the above process, and complete the detection of the entire working face. The process is shown in Figure 3 (the detection process is carried out in the direction of the arrow, the same below).
2.2 "One send, two receive" working mode
"One transmit and two receive" working mode, that is, one transmitter and two receivers
After the transmission is completed, A moves to the No. 2 launch point to transmit, and C receives data normally, while B waits at the start position corresponding to the receiving segment of the No. 3 launch point. Repeat this until the measurement is complete. Finally, A, B, and C exchange roadways, repeat the above process, and complete the detection of the entire working face.
As shown in Figure 5, let the transmitter be A, and the receivers be B and C respectively. First, A transmits at the No. 1 transmitting point, B receives at the beginning of the corresponding receiving section, and C receives at the middle of the corresponding receiving section at the same time, and both only receive half of the data. Wait for launch point 1 to be launched, and A moves to
Fig. 4 Schematic diagram of "one transmission, two receptions" and "interval" method Fig. 5 "One transmission, two receptions" and "synchronization" method
The next transmitting point, B moves to the next transmitting point and starts to connect to the corresponding receiving section, C moves to the next transmitting point and corresponds to the middle position of the receiving section, after A, B, and C are all in place, A starts to transmit, B, C Receive at the same time, and only receive half of the data. Repeat this until the measurement is complete. Finally, A, B, and C exchange roadways, repeat the above process, and complete the detection of the entire working face.
The mode of "double transmission and double reception" means that two transmitters and two receivers work together, and can also be divided into "interval" and "synchronous" methods.
As shown in Figure 6, let the transmitters be A and B, and the receivers be C and D. First, A transmits at the No. 1 transmitting point. During this period, C normally receives, B waits for the next transmitting point, and D waits for the starting receiving position of the next transmitting point. After No. 1 launch point finishes transmitting, B starts to transmit, D starts to receive, A goes to the next launch point to wait, C goes to the next launch point to start
Start receiving position waiting. Repeat this until the measurement is complete. Finally, A, B and C, D exchange roadways, repeat the above process, and complete the detection of the entire working face.
As shown in Figure 7, let the transmitters be A and B, and the receivers be C and D. First, A transmits at the No. 1 transmitting point, C starts receiving at the position corresponding to the receiving section, and D starts receiving at the middle position of the corresponding receiving section at the same time, and both only receive half of the data in the receiving section, while B waits for the next transmitting point. After the transmission of point 1 is completed, A moves to the next transmission point and waits, C moves to the start position of B corresponding to the receiving segment and D moves to the middle position of B corresponding to the receiving segment, and when C and D are in place, B starts to transmit. C and D start receiving at the same time, and both receive only half of the receive segment time. Repeat this until the measurement is complete. Finally, A, B, C, and D exchange roadways, repeat the above process, and complete the detection of the entire working face.
Fig. 6 Schematic diagram of "double transmission and double reception" and "interval" method Fig. 7 Schematic diagram of "double transmission and double reception" and "synchronous" method
For the super-long working face, the combination mode can be considered for detection. Since the transmitters interfere with each other, only one transmitter can work at the same time, and more than two transmitters are meaningless, so only the combination of 1+1 is considered, that is, two detection groups, the transmitters of which are in different lanes, alternately Transmit and receive until the detection is complete.
As shown in Figure 8, let the transmitters be A and C, the receivers be B and D, A and B are one measurement group, and C and D are another measurement group. A is located at the No. 1 launch point of a lane, B is located at the beginning of the corresponding receiving section, C is located at the No. 1 launching point of another lane, and D is located at the beginning of the corresponding receiving section. First A transmits and B receives. After A finishes transmitting, C starts to transmit, and D starts to receive. At the same time, A moves to the next transmitting point, and B moves to the starting position of the corresponding receiving segment. After the transmission of C is completed, A starts to transmit, and at the same time, C moves to the next transmission point, and D moves to the starting position of the corresponding receiving segment. Repeat this until the measurement is complete.
It is worth noting that in this measurement mode, there is no need to exchange roadway measurements. And it can be regarded as another method of the "double sending and double receiving" mode, that is, the "crossover" method.
Figure 8. Schematic diagram of the combination of "one send and one receive"
As shown in Figure 9, let the transmitters be A and D, and the receivers be B, C, E and F. A, B, and C are one measurement group, and D, E, and F are another measurement group. Each group adopts the "one send, two receive" synchronization method. A is located at the No. 1 launch point of a lane, B is located at the beginning of the corresponding receiving section, C is located at the middle of the corresponding receiving section, D is located at the No. 1 launch point of another lane, and E is at the
At the start position of the corresponding receiving segment, F is located in the middle of the corresponding receiving segment
Figure 9. Schematic diagram of the combination of "one send and two receive"
A transmitting point moves, B moves to the start position of the corresponding receiving segment, and C moves to the middle position of the corresponding receiving segment. After D's launch is completed, A starts to launch, and at the same time D moves to the next launch point, E moves to the start position of the corresponding receiving section, and F moves to the middle position of the corresponding receiving section. Repeat this until the measurement is complete.
Through the analysis of the above working modes, the calculation formulas of the main engine’s walking distance, total detection time, time utilization rate, walking speed, and the maximum detectable working face length in various modes are obtained. See Table 1 for details.
Classified according to the maximum detectable working face length, the working modes can be divided into three categories: the first category is "one send and one receive" and "one send and two receive", the second category is "double send and double receive" (putting "one send and two receive" The combination mode of "send and receive" is regarded as the "crossover" method of the "double send and double receive" mode), and the third type is the combination of "one send and double receive". The maximum detectable length of different combined modes in each category is the same, but the detection length of the third category is twice that of the second category, and the detection length of the second category is twice that of the first category.
According to the total detection time and total time utilization, the working mode can be divided into two categories: the first category is "one transmission and one reception" and "one transmission and two receptions", and the second category is "two transmissions and two receptions" and combination mode. The total detection time and the total time utilization of different modes in each category are the same. To reduce the total detection time, the first type of mode needs to reduce the sum of launch time and station moving time, and the second type of mode only needs to reduce the launch time. For the total time utilization, the first type is smaller than the second type, which is related to the launch time and station moving time; while the second type is constant and reaches the maximum value
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