In a mine of Lu'an Mining (Group) Co., Ltd, elastic wave CT technology is used to detect the S3-10 working face, which is located in the range of 180-780m from the cutting eye in the belt chute and track chute, and the specific location of the detection is shown in Fig. 1.
The purpose and task of this exploration is to detect the development of geological structures such as faults, trap columns and coal and rock seam fracture zones within the range of 180-780m from the cutting eye of the S3-10 working face, so as to provide a reference basis for the mining of the S3-10 working face.
Figure 1 Schematic diagram of the detection area (red line)
This time, for the investigation of the tectonic development of S3-10 working face of No.3 coal seam in the range of 180-780m from the cutting eye, according to the site conditions and the detection task, we adopt the elastic wave CT perspective method, and firstly, we lay out 16 holes in the skin belt along the groove of the S3-10 working face (of which the first hole is a test hole), and we lay out 5 groups of receiving points in the track along the groove of the S3-10 working face, and each group will discharge the gun 3 times, and each gun will receive 24 physical points, and each gun will be spaced 5m apart. The working face of S3-10 is arranged with 15 holes in the track and 5 groups of receiving points in the belt groove, each group will fire 3 times and each gun will receive 24 physical points with a spacing of 5 m. The schematic diagram of on-site construction arrangement is shown in Fig. 2.
Figure 2 Site construction layout of the gun site
Figure 3 S3-10 elastic wave perspective detection results map (red line circled area is the wave speed anomaly area)
The above figure shows the results of elastic wave perspective detection in the range of 180-780m from the cutting eye in the belt groove and track groove of S3-10 working face. In the figure, the blue color scale indicates the low wave speed value, and the red color scale indicates the high wave speed value. The darker blue color indicates the higher possibility of anomalies, so the internal structure and its characteristics can be determined.
As seen in Fig. 3, the integrated wave speed anomaly zones in the detection area are as follows:
Anomaly zone YC-1: 303-403m from the cutting eye, 38-145m from the belt groove and 115-222m from the track groove.
Abnormal zone YC-2: 280-360m from the cutting eye, 183-260m from the belt chute, 0-77m from the track chute.
Abnormal zone YC-3: 370-440m from the cutting eye, 178-260m from the belt chute, 0-82m from the track chute.
Abnormal zone YC-4: 585-633m from the cutting eye, 0-67m from the belt chute, 193-260m from the track chute.
4.Conclusion
Compared with the surrounding area, the comprehensive wave velocity value of the anomaly area YC-1 is below 2000nm/s, which is relatively small compared with other areas, and it is a relatively low velocity area in the working face. Combined with the on-site conditions and geological data, we comprehensively analyze that the anomaly area YC-1 is the tectonic influence of the nodal fissure development zone of the coal beds or the trap columns and other tectonic influences, and the range of coal seam changes.
Compared with the surrounding area, the comprehensive wave velocity value of the anomaly area YC-2 and YC-3 is below 1400m/s, which is relatively small, and it is a relative low velocity area in the working face. Combined with the on-site conditions and geological data, the comprehensive analysis of the anomaly area YC-2 and YC-3 is the influence of the waste gun point, with fewer localized data, formed by interpolation in the processing software system, and there is no possibility of tectonic existence.
Compared with the surrounding area, the comprehensive wave speed value of the anomaly area YC-4 is 2000-2200m/s, which is slightly smaller than the surrounding wave speed value, and analyzed as the relative low speed anomaly area in the working face. Combined with the on-site conditions and geological data, the comprehensive analysis of the anomaly area YC-4 is the influence range of Fj146 which is exposed in the course of the roadway excavation of the working face belt tunnels, and the red dotted line in the figure is the direction of the inferred fault and its extension range.
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Mining Video Imaging Logging Instrument