Method for grouting coal seam roof through ground-hole transient electromagnetic monitoring
Technical Field
The invention relates to a method for monitoring grouting of a coal seam roof, in particular to a method for monitoring grouting of a coal seam roof through ground-hole transient electromagnetism, and belongs to the field of water control of a coal mine mining well.
Background
The fourth aquifer (four-water-containing for short) in the unconsolidated formation of the new kingdom is in direct contact with the coal measure formation, the four-water-containing seriously threatens the safe mining of the shallow coal seam, the drop between the four-water-containing and the fault is only dozens of meters, and the main method for solving the problem of the four-water-containing of the top plate at present is ground punching grouting. But there is no effective method for evaluating the distribution range and grouting effect of the grouted slurry. Based on the problem, the ground-borehole transient electromagnetic exploration method research of ground transmitting-receiving in the well is provided, and the grouting effect is reasonably evaluated. The high-power coil is laid on the ground, and the receiving probe is placed in the hole to receive the axial transient electromagnetic field, so that the aim of detecting the distribution of the geological resistivity around the drill hole is fulfilled. The detection method has the advantages that the sensor is received to be close to the geological abnormal body, the abnormal response signal intensity is increased, the resolution ratio is increased, and the spatial position of the geological abnormal body around the hole can be detected more sensitively. Therefore, the transient electromagnetic detection mode is very suitable for monitoring and evaluating the grouting effect of the drilling hole.
Disclosure of Invention
The invention has the following problems: aiming at the technical problems, the invention provides a ground-hole transient electromagnetic monitoring coal seam roof grouting method which combines a transient electromagnetic observation system and a working method with actual geological conditions, lays a large magnetic moment emission wire frame on the ground, sends a probe to a grouting target part through a drill hole, detects once before grouting and once after grouting, compares the two detection results and analyzes the difference change of the two detection results, and can realize the evaluation of grouting effect.
The technical scheme is as follows: in order to achieve the technical purpose, the transient electromagnetic monitoring method for the grouting effect of the coal seam roof uses a high-power transmitter, a magnetic field sensor, an industrial and mining host, a high-power transmitting wire frame and a high-sensitivity magnetic probe, wherein the high-power transmitting wire frame is connected with the high-power transmitter, and the high-power transmitter and the high-sensitivity magnetic probe are respectively connected with the industrial and mining host.
The method comprises the following steps:
step one, laying a high-power transmitting wire frame on the ground, lowering a high-sensitivity magnetic probe into a drill hole before grouting, using the high-power transmitting wire frame to send a transient electromagnetic signal after the high-sensitivity magnetic probe descends for a certain distance, receiving a magnetic field signal through the high-sensitivity magnetic probe, and recording the measuring point depth of the received magnetic field signal;
secondly, grouting the drill hole, lowering the high-sensitivity magnetic probe into the drill hole after grouting, sending a transient electromagnetic signal by using a high-power transmission wire frame after the high-sensitivity magnetic probe descends for a certain distance, receiving a magnetic field signal by the high-sensitivity magnetic probe, and recording the depth of a measuring point for receiving the magnetic field signal;
and step three, comparing two groups of signals collected at the same depth before and after grouting, if the electrical response characteristics of the two signals before and after grouting at the same depth are consistent or the difference is smaller, indicating that the grouting effect at the drilling depth of the high-sensitivity magnetic probe is poor, otherwise indicating that the grouting effect is good, and finally obtaining the position mark with poor grouting in the whole grouting drilling hole, thereby providing a basis for subsequent reinforcement construction.
The method comprises the following steps:
a, before grouting, a coal seam roof, paving a high-power transmitting wire frame on the ground around a drill hole, surrounding the drill hole, positioning the hole at the center of the wire frame as far as possible, marking depth information on a cable connected with a high-sensitivity magnetic probe, and knowing the depth of the high-sensitivity magnetic probe in the drill hole through the depth;
b, lowering the high-sensitivity magnetic probe into the borehole and lowering the high-sensitivity magnetic probe to a predicted grouting position;
c, exciting transient electromagnetic signals to the ground below by using a high-power transmitter through a high-power transmitting wire frame;
d, receiving and recording the secondary magnetic field signal by using a high-sensitivity magnetic probe, storing and recording in the industrial and mining host according to the depth information marked by the cable, wherein the stored information is stored as pre-grouting detection data in the form of [ depth, decay time and secondary magnetic field signal ];
e, grouting the coal seam roof by using the top plate grouting drill hole, lowering the high-sensitivity magnetic probe to the grouting position in the drill hole after grouting, and predicting the depth of the grouting position;
f, when the high-sensitivity magnetic probe is lowered to the grouting layer, using a high-power transmitting wire frame to transmit magnetic field signals to the ground below, and simultaneously receiving secondary magnetic field signals by the high-sensitivity magnetic probe;
g, recording a secondary magnetic field signal received by the high-sensitivity magnetic probe in a drill hole, storing and recording in the industrial and mining host according to depth information, wherein the stored information is stored as post-grouting detection data in a form of [ depth, decay time and secondary magnetic field signal ];
h, respectively generating two groups of graphs by two groups of secondary magnetic field signals acquired before and after top plate grouting, drilling and grouting, and comparing the change amplitudes of the secondary magnetic field signals acquired at the same depth in the two groups of graphs, wherein if the two graphs have the same change or the difference is smaller at the same time, the fact that the electrical response characteristics of the part before and after grouting are the same or the difference is smaller indicates that the grouting has less influence on the formation resistivity, and the grouting effect of the part is poor; if the two curve graphs before grouting change obviously at the same time, the difference of the electrical response characteristics of the two curve graphs is large, which indicates that the grouting has a large influence on the formation resistivity and the grouting effect at the position is good.
When the high-sensitivity magnetic probe reaches a position to be detected, the high-power transmission wire frame is used for transmitting electromagnetic waves to the drilling direction of a drill hole, the high-sensitivity magnetic probe is used for receiving corresponding secondary magnetic field signals, the high-sensitivity magnetic probe only stops at the drilling grouting depth to be detected to receive the electromagnetic waves transmitted by the primary high-power transmission wire frame according to the detection requirement, or the high-sensitivity magnetic probe transmits the electromagnetic waves through the high-power transmission wire frame at each descending end distance according to the detection requirement, then the secondary magnetic field signals received by the high-sensitivity magnetic probe are arranged according to the depth, so that a secondary magnetic field signal curve is formed by fitting, and the effect of the whole drilling grouting end is conveniently evaluated.
The magnetic moment emission wire frame ensures the detection depth, the size of the high-power emission wire frame is a square wire frame of 100m multiplied by 100m, and the size of the current carried by the wire is 20A.
And the high-sensitivity magnetic probe is lowered into the drill hole through a lifter, the depth of the high-sensitivity magnetic probe is read through the marking of the cable, and the high-sensitivity magnetic probe returns to the ground through the lifter after the measurement is finished.
The high-sensitivity magnetic probe is a high-sensitivity magnetic probe of a model YCS 400.
Has the advantages that: according to the invention, a large magnetic moment emission wire frame is laid on the ground, the probe is conveyed to a grouting target part through a drill hole, primary detection is respectively carried out before and after grouting, the difference change of the two detection results is analyzed by comparing the two detection results, the electrical response characteristic of the grouting target layer position can be effectively and quickly obtained, and finally, the grouting effect evaluation is realized.
Drawings
FIG. 1 is a schematic diagram of an implementation of the method for grouting a coal seam roof through transient electromagnetic monitoring of a ground-hole according to the invention;
FIG. 2 is a diagram of multi-channel data before grouting according to the method for coal seam roof grouting transient electromagnetic monitoring of the invention;
FIG. 3 is a multi-channel data plot after grouting according to the method for grouting a coal seam roof for transient electromagnetic monitoring of a ground-hole in accordance with the present invention;
FIG. 4 is a comparison graph of multi-channel data before and after grouting according to the method for grouting a coal seam roof through transient electromagnetic monitoring of a ground-hole;
FIG. 5 is a flow chart of a method for monitoring grouting of a coal seam roof through hole transient electromagnetic monitoring according to the present invention
Detailed description of the invention
The invention will be further described with reference to the following examples in which the accompanying drawings are set forth in detail:
as shown in fig. 1 and 5, the method for monitoring grouting of a coal seam roof by using ground-hole transient electromagnetism of the invention uses a high-power transmitter, a controller, a mining host, a high-power transmitting wire frame and a high-sensitivity magnetic probe, wherein the high-power transmitting wire frame is connected with the high-power transmitter and is controlled by the controller, and the high-power transmitter and the high-sensitivity magnetic probe are respectively connected with the mining host.
The method comprises the following steps:
step one, arranging a high-power transmitting wire frame on the ground, lowering a high-sensitivity magnetic probe into a drill hole before grouting, using the high-power transmitting wire frame to send a transient electromagnetic signal after the high-sensitivity magnetic probe descends for a certain distance, receiving a magnetic field signal through the high-sensitivity magnetic probe, and recording the measuring point depth of the received magnetic field signal;
secondly, grouting the drill hole, lowering the high-sensitivity magnetic probe into the drill hole after grouting, sending a transient electromagnetic signal by using a high-power transmission wire frame after the high-sensitivity magnetic probe descends for a certain distance, receiving a magnetic field signal by the high-sensitivity magnetic probe, and recording the depth of a measuring point for receiving the magnetic field signal;
and step three, comparing two groups of signals collected at the same depth before and after grouting, if the electrical response characteristics of the two signals before and after grouting at the same depth are consistent or the difference is smaller, indicating that the grouting effect at the drilling depth of the high-sensitivity magnetic probe is poor, otherwise indicating that the grouting effect is good, and finally obtaining the position mark with poor grouting in the whole grouting drilling hole, thereby providing a basis for subsequent reinforcement construction.
The method comprises the following specific steps:
a, before grouting, a coal seam roof, paving a high-power transmitting wire frame on the ground around a drill hole, surrounding the drill hole, positioning the hole at the center of the wire frame as far as possible, marking depth information on a cable connected with a high-sensitivity magnetic probe, and knowing the depth of the high-sensitivity magnetic probe in the drill hole through the depth; the detection depth is ensured by the magnetic moment emission wire frame, the size of the high-power emission wire frame is a square wire frame of 100m multiplied by 100m, and the size of the current carried by the wire is 20A.
b, lowering the high-sensitivity magnetic probe into the borehole and lowering the high-sensitivity magnetic probe to a predicted grouting position; the high-sensitivity magnetic probe is of a model YCS400, is lowered into the drill hole through a lifter, is lowered into the drill hole, reads the depth of the high-sensitivity magnetic probe through the marking of a cable, and returns to the ground through the lifter after the measurement is finished;
c, exciting transient electromagnetic signals to the ground below by using a high-power transmitter through a high-power transmitting wire frame;
d, receiving and recording the secondary magnetic field signal by using a high-sensitivity magnetic probe, storing and recording in the industrial and mining host according to the depth information marked by the cable, storing the stored information as the detection data before grouting in the form of [ depth, secondary magnetic field signal ], fitting the detection data as shown in figure 2,
e, grouting the coal seam roof by using the top plate grouting drill hole, lowering the high-sensitivity magnetic probe to the grouting position in the drill hole after grouting, and predicting the depth of the grouting position;
f, when the high-sensitivity magnetic probe is lowered to the grouting layer, using a high-power transmitting wire frame to transmit magnetic field signals to the ground below, and simultaneously receiving secondary magnetic field signals by the high-sensitivity magnetic probe;
g, recording a secondary magnetic field signal received by the high-sensitivity magnetic probe in a drill hole, storing and recording in the industrial and mining host according to depth information, storing the stored information in a form of [ depth, decay time and secondary magnetic field signal ] as post-grouting detection data, fitting the detection data as shown in figure 2,
h, as shown in fig. 4, two groups of secondary magnetic field signals acquired before and after top plate grouting drilling grouting are respectively generated into two groups of graphs, the change amplitude of the secondary magnetic field signals acquired at the same depth in the two groups of graphs is compared, if the two graphs change consistently or have small difference at the same time, the electrical response characteristics of the place before and after grouting are consistent or have small difference, and the situation that the influence of grouting on the formation resistivity is small and the grouting effect is poor is indicated; if the two curve graphs before grouting change obviously at the same time, the difference of the electrical response characteristics of the two curve graphs is large, which indicates that the grouting has a large influence on the formation resistivity and the grouting effect at the position is good.
When the high-sensitivity magnetic probe reaches a part to be detected, the high-power transmission wire frame is used for transmitting electromagnetic waves to the axial direction of the drill hole, the high-sensitivity magnetic probe is used for receiving corresponding secondary magnetic field signals, the high-sensitivity magnetic probe only stays at the drill hole grouting depth to be detected to receive the induced secondary magnetic field according to the detection requirement, or the high-sensitivity magnetic probe transmits the electromagnetic waves through the high-power transmission wire frame when descending for a certain distance, then the secondary magnetic field signals received by the high-sensitivity magnetic probe are arranged according to the depth, so that a secondary magnetic field signal curve is formed by fitting, and the effect of the whole drill hole grouting end is convenient to evaluate.