Position determining and blocking method for centralized underground runoff in karst mining area

Abstract

The invention discloses a karst mining area concentrated underground runoff position determining and blocking method. According to the technical scheme, the method comprises the following steps that S1, the boundary and the flow direction of an aquifer are determined according to previous hydrogeological data; s2, a high-density electrical method is adopted for detection, and the position of the axis of the curtain is preliminarily selected; s3, the approximate position of a runoff channel is determined on the two sides of the preliminarily determined curtain axis through a transient electromagnetic method; s4, drilling is conducted in the abnormal area of the axis of the curtain, a tracer agent is put into a drill hole, a tracer agent signal is received at an underground water outlet point, and the position of a runoff channel is accurately determined; s5, after drilling is conducted on the runoff channel, grouting and plugging are conducted in a segmented mode; according to the method, a high-density electrical method and a transient electromagnetic method are combined, and the accuracy of channel positioning is improved through staged detection; the tracer technology realizes the accurate verification of the channel position, and reduces the misjudgment risk; and finally, a segmented grouting plugging mode of upstream and downstream densification and midstream reinforcement is adopted, so that the stability and durability of the plugging structure are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of exploration and exploitation, and in particular to a method for determining and plugging the position of concentrated underground runoff in a karst mining area. Background Art

[0002] A contact metasomatic deposit refers to a deposit formed by the metasomatism of ore-bearing hydrothermal fluids at or near the contact zone between intermediate-acid to intermediate-basic intrusive rocks and carbonate rocks, also known as a skarn deposit. It is a type of deposit with important industrial significance and is widely distributed. Skarn deposits mostly belong to large-water karst deposits with complex hydrogeological conditions, such as Anqing Copper Mine, Linihu Copper-Iron Mine, and Xinqiao Pyrite Mine in the middle and lower reaches of the Yangtze River in China. In karst mining areas, due to the complex geological structure, karst caves, gullies, and troughs are concentrated in the shallow part (usually within 50 meters from the surface), and karst development gradually stagnates in the deep part due to the weakening of hydrodynamic conditions. Because of the good groundwater alternation conditions in the shallow part, atmospheric precipitation quickly infiltrates through fractures, carrying a large amount of corrosive substances such as CO2, accelerating the dissolution of carbonate rocks. The active dissolution-erosion action of shallow groundwater and the water-conducting effect of tectonic fractures form a positive feedback, forming large-scale underground runoff karst channels in the upper and middle parts of carbonate rocks. Especially under the influence of underground mining drainage, the hydraulic gradient increases, groundwater activity is strong, and the filling in the dissolution channels is easily washed away, resulting in unobstructed runoff channels and increasing the risk of water inrush in the mine. In addition, during the rainy season, the runoff channels are connected to the shallow water bodies, easily causing instantaneous large-scale water inrush and mud inrush in the mine pit, which in turn leads to the occurrence of shaft flooding accidents and causes secondary disasters such as ground collapse.

[0003] Since a large amount of groundwater pumping and drainage for the development of such deposits will cause extensive karst ground collapse, damaging the local ecological environment and causing economic losses. To safely and smoothly develop such resources, generally, impermeable intrusive rock masses are used to carry out a bottom-sealed curtain water-blocking project in the carbonate rock mass in the direction of karst groundwater runoff, which is extremely costly and has an extremely long construction period. There are also measures to intercept the flow by targeting the channels of the main karst runoff. The existing channel positioning methods rely on geophysical exploration techniques, and the work deployment is relatively discrete or the detection means are relatively single, resulting in limited accuracy, low detection accuracy of runoff channels, and high risks. Moreover, the directional plugging construction lacks systematic design. When using cement slurry or polymer materials for plugging, the slurry is easily washed away under the conditions of large flow and high velocity, making it difficult to completely block the runoff channel, and the failure risk is high. Summary of the Invention

[0004] In order to accurately detect the position of underground runoff and plug it, the present application provides a method for determining and plugging the position of concentrated underground runoff in a karst mining area.

[0005] The present application provides a method for determining and plugging the position of concentrated underground runoff in a karst mining area, adopting the following technical solutions:

[0006] S1. Determine the aquifer boundaries and flow direction based on previous hydrogeological data;

[0007] S2. Use high-density electrical detection to preliminarily select the curtain axis position;

[0008] S3. On both sides of the initially determined curtain axis, use the transient electromagnetic method to determine the approximate location of the runoff channel;

[0009] S4. Drilling is carried out in the abnormal area of ​​the curtain axis, a tracer is placed into the borehole, and the tracer signal is received at the water outlet point downhole to accurately determine the location of the runoff channel;

[0010] S5. Drill holes in the runoff channel and then seal it with grouting in sections.

[0011] Optionally, step S2 is specifically as follows: arranging multiple mesh high-density electrical detection lines in the mining area to find out the distribution range of the aquifer in the plane and vertical direction; preliminarily selecting the curtain axis position according to the shallowest buried position of the water-blocking bottom plate in the vertical section, with the measuring point spacing being 5m.

[0012] Optionally, the step S3 is specifically as follows: within a range of 20 meters on both sides of the initially determined curtain axis, a plurality of transient electromagnetic survey lines with a point spacing of less than or equal to 2 meters are arranged, and the approximate position of the runoff channel is determined by abnormal signal analysis.

[0013] Optionally, before step S5, it is also necessary to explore the scale of cave development and water permeability in the borehole that exposes the runoff channel to provide parameter support for subsequent plugging design.

[0014] Optionally, in step S5, the drilling construction sequence is downstream first and then upstream, and the grouting adopts a combination of aggregate placement, paste grouting material filling and double-liquid slurry grouting; after completing the upstream and downstream grouting, reinforced grouting holes are constructed in the midstream area, and supplementary grouting is carried out to ensure the integrity of the plugging.

[0015] In summary, this application includes the following beneficial technical effects:

[0016] This application combines high-density electrical method and transient electromagnetic method. Phased detection improves the accuracy of channel positioning. At the same time, tracer technology realizes accurate verification of channel position and reduces the risk of misjudgment. Finally, the segmented grouting and plugging method of upstream and downstream encryption + midstream reinforcement is adopted to enhance the stability and durability of the plugging structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional stereogram of the object detection line results of the embodiments T4, T5 and T6 of the present application;

[0018] Figure 2This is a diagram of the precise detection results of the transient electromagnetic method in the embodiment of the present application;

[0019] Figure 3 is a tracer concentration variation curve diagram of an embodiment of the present application;

[0020] Figure 4 It is a schematic diagram of the drilling and plugging solution of an embodiment of the present application. DETAILED DESCRIPTION

[0021] The following is combined with Figures 1-4 This application is described in further detail.

[0022] The embodiment of the present application discloses a method for determining the location of concentrated underground runoff in a karst mining area and blocking it. A copper mine in Anqing is taken as an example. The copper mine is located in the middle of the iron-copper mineralization belt in the middle and lower reaches of the Yangtze River. The deposit is a contact metasomatic skarn-type lens-shaped copper-iron deposit. The hydrogeological conditions are moderate, and the unified aquifer is composed of three different marbles of the Triassic T2y2, T2y1, and T1n. It is a typical karst metal water mine in southern my country. It was put into production in 1987. During the infrastructure and production process, a large amount of water gushed out when the underground development project exposed the limestone roof, causing environmental geological problems such as surface karst collapse and surface water backflow. Especially in the Mashankou section where the Maanshan River flows, the karst collapse is more intense and the collapse holes are dense. In recent years, many new and repeated collapses have occurred around and in the river channel.

[0023] The specific steps are as follows:

[0024] S1. Collect previous geological and hydrogeological data to determine the boundaries and flow direction of aquifers

[0025] Using the exploration data of the mining area, the lateral recharge boundary and groundwater flow direction of the aquifer in the mining area are analyzed and determined, laying the foundation for subsequent detection.

[0026] S2. High-density electrical detection

[0027] The high-density resistivity method observes underground resistivity anomalies through multi-electrode arrangement scanning, and combines electrical profile, depth sounding and tomography technology to quickly generate images, which is suitable for macroscopically grasping the laws of karst development. A mesh high-density electrical detection line is arranged in the mining area to find out the distribution range of the aquifer in the plane and vertical direction; the curtain axis position is preliminarily selected based on the shallowest buried position of the water-blocking bottom plate in the vertical profile.

[0028] A total of 11 high-density electrical survey lines were laid out. Three survey lines were laid out in the near east-west direction, T4 to T6 from south to north; three survey lines were laid out in the near north-south direction, G1 to G3. G4 to G5 lines were laid out on both sides of the West Ma'anshan River; T1 to T3 and T7 were laid out in East Ma'anshan and on both sides of the river; high-density resistivity sounding method, the measuring point spacing is 5m, and the detection depth is 150m.

[0029] Combination Figure 1 The results of high-density electrical detection show that the two ends of the east-west survey line present relatively high resistance. Combined with geological data, they are all composed of calcareous siltstone in the upper section of the T2y3 Yueshan Formation, which are generally impermeable bodies with very weak or no water. The middle area of ​​the survey line is a large low-resistance area, and there are clear hydrogeological boundary conditions on the plane of the Mashankou section.

[0030] The resistivity is high below the -50m elevation, indicating that the bottom rock layer below the -50m elevation has weak water content. According to geological data, the vertical karst development depth is limited, generally developing to -50 to -100m elevation, and the karst development degree of deep rock layers is low.

[0031] From the three geophysical exploration profiles of the adjacent east-west survey lines T4 / T5 / T6, the low-resistance range of the T6 line is the shallowest, and the lower the range is, the deeper it is as it goes south. The shallow low-resistance is connected into a piece, which corresponds to the plane collapse-prone area. According to the data, the collapses in history are mostly located south of the T6 survey line. The collapse-intensive area is mainly located at the mileage of 100-260m of the T6 line and the 300-350m position of the eastern river near Ma'anshan. The karst channels are relatively concentrated, and the Anqing copper mine area north of the T6 line is less prone to collapse.

[0032] S3. Detailed Study on Transient Electromagnetic Method

[0033] Within the range of 20 meters on both sides of the initially determined curtain axis T6 survey line, three transient electromagnetic survey lines with a point spacing of less than or equal to 2 meters are arranged to determine the approximate location of the runoff channel through abnormal signal analysis. The transient electromagnetic method has a large detection depth, is sensitive to deep karst pipelines, and can accurately detect the distribution of deep channels.

[0034] Based on the preliminary work, three parallel survey lines were arranged. Y3 is the original grouting axis t6. Along the groundwater flow direction, Y1 and Y2 are located upstream and downstream of the runoff channel respectively. In order to further accurately detect the karst development channel, the point spacing is increased to 0.5-1m.

[0035] Combination Figure 2 , three runoff channels can be clearly seen from south to north. From north to south, the measurement results of the three measurement lines (Y1 / Y3 / Y2) show that each measurement section has three strip-shaped low-resistivity anomaly areas. It is speculated that these anomalies are caused by groundwater in the karst pipes, and these areas are considered to be the locations of underground runoff. At the same time, the central and eastern channels are also the locations where faults F2, F7 and their fault zones are developed, and the width of the leakage zone is 10 to 40 meters. The low-resistivity anomaly area on the west side is relatively large in plane range and is located at the contact zone between intrusive rocks and carbonate rocks. It may be caused by mineralization. There is the possibility of groundwater flow channels, which requires further drilling verification.

[0036] Comprehensive analysis shows that karst development mainly occurs in the shallow part of the fault zone and the contact zone between soluble rock and gabbro, especially the fault structure, which plays a controlling role in karst development. Combining with the hydrogeological structure and boundary conditions of Anqing Copper Mine, it is inferred that the concentrated area of underground runoff is located at the above three positions.

[0037] S4. Drilling and tracer verification

[0038] Drill in the abnormal area of the curtain axis, put tracers into the drill holes, and receive tracer signals at the underground water outlet points to accurately determine the position of the runoff channel.

[0039] S5. In the drill holes that expose the runoff channel, explore the development scale and water permeability of the karst caves to provide parameter support for the subsequent plugging design.

[0040] Combined with Figure 3 , the test results show that the hydraulic connection between the mine pit and the drill hole groundwater is close. The flow velocity of groundwater between the feeding point and each detection point is 2.75 - 10.91 m / h, which is related to the relatively large hydraulic gradient at the edge of the groundwater funnel where it is located, and the flow velocity is relatively fast.

[0041] S6. Arrange two rows of densified grouting holes upstream and downstream of the runoff channel respectively, and control the row spacing within 3 to 4 meters;

[0042] Combined with Figure 4 , the construction sequence of the drill holes is from downstream to upstream, and the grouting adopts a combination of aggregate placement, paste grouting material filling and double-fluid grouting;

[0043] After the upstream and downstream grouting is completed, construct reinforcement grouting holes in the middle area for supplementary grouting to ensure the integrity of the plugging.

[0044] The above are all preferred embodiments of this application. The protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape and principle of this application should be covered within the protection scope of this application.

Claims

1. A method for determining and plugging the position of concentrated underground runoff in a karst mining area, characterized in that The steps include: S1. Determine the aquifer boundaries and flow direction based on previous hydrogeological data; S2. Use high-density electrical detection to preliminarily select the curtain axis position; S3. On both sides of the initially determined curtain axis, use the transient electromagnetic method to determine the approximate location of the runoff channel; S4. Drilling is carried out in the abnormal area of ​​the curtain axis, a tracer is placed into the borehole, and the tracer signal is received at the water outlet point downhole to accurately determine the location of the runoff channel; S5. Drill holes in the runoff channel and then seal it with grouting in sections.

2. The method for determining and plugging the position of centralized underground runoff in a karst mining area according to claim 1, characterized in that: The step S2 is specifically as follows: a plurality of meshed high-density electrical detection lines are arranged in the mining area to find out the distribution range of the aquifer in the plane and vertical direction; based on the shallowest buried position of the water-blocking bottom plate in the vertical section, the curtain axis position is preliminarily selected, and the measuring point distance is 5m.

3. The method for determining and plugging the position of centralized underground runoff in a karst mining area according to claim 2, characterized in that: The step S3 specifically includes: arranging a plurality of transient electromagnetic survey lines with a point spacing of less than or equal to 2 meters within a range of 20 meters on both sides of the initially determined curtain axis, and determining the approximate location of the runoff channel through abnormal signal analysis.

4. A method for determining and plugging the position of concentrated underground runoff in a karst mining area according to claim 1, characterized in that: Before step S5, it is also necessary to explore the scale and permeability of the cave development in the borehole that exposes the runoff channel to provide parameter support for the subsequent plugging design.

5. A method for determining and plugging the position of concentrated underground runoff in a karst mining area according to claim 1, characterized in that: In step S5, the drilling construction sequence is downstream first and then upstream, and the grouting adopts a combination of aggregate placement, paste grouting material filling and double-liquid grouting; after completing the upstream and downstream grouting, reinforced grouting holes are constructed in the midstream area, and supplementary grouting is carried out to ensure the integrity of the plugging.

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