A method for prospecting the scope of a sand mining area

Abstract

The present invention discloses a method for investigating the scope of a sand mining area, comprising the following steps: S1. Investigate and determine the planar scope of the sand mining area; S2. Investigate and determine the mining depth of the sand mining area, specifically including: S21. Analyze the surface conditions before and after mining in the planar scope of the sand mining area by using the cross-section method; S22. Apply the geophysical prospecting method to determine the initial lithology and the change of the initial deep mining depth; S23. Use the core drilling method to determine the deep lithology mining depth; S24. Apply the dynamic penetration method to verify the deep gravel mining depth of the same lithology and determine the mining depth of the sand mining area; S3. Divide the planar scope of the mining area in the target area into four areas according to the mining depth and lithology differences, namely the water pit area, the coarse-grained soil area, the fine-grained soil area, and the mixed area. This method comprehensively investigates and finds out the planar scope and the mining depth, the method is reliable, the cost is controllable, and the spatial distribution of the sand mining area can be determined; at the same time, different areas in the sand mining area are classified and evaluated, providing a reliable scientific theoretical basis for subsequent design and construction in the target area.

Description

Technical Field

[0001] The present invention relates to the field of traffic and waterway engineering surveys, and particularly to a method for surveying the scope of a sand mining area. Background Art

[0002] With the increase in engineering construction, the demand for sand and gravel has increased significantly. More and more sand and gravel in river channels and near-shore river terraces have been mined, and illegal sand mining has also become more and more prevalent, forming many artificial sand mining pits. The scope of sand and gravel mining is called the sand mining area, including the planar scope and depth scope of sand mining. Due to the long sand mining time, the sand mining scope and depth are not very regular. Existing research shows that sand mining has a greater impact on engineering construction near the riverbank slope, and the sand mining area has potential dangers. Therefore, the survey of the sand mining area has great safety and economic significance for the utilization research of the sand mining area.

[0003] There is relatively little research on the survey method of the sand mining area in China. For the survey of the sand mining area site, the main reference is enterprise specifications. In actual processes, the method of combining measurement, drilling, and high-density geophysical prospecting is usually adopted. For example, the "Code for Geotechnical Investigation of Water Transport Engineering" (JTS133-2013) of CCCC Second Harbor Engineering Investigation and Design Institute Co., Ltd. and Changjiang Waterway Planning, Design and Research Institute, the "Code for Geological Investigation of Highway Engineering" (JTGC20-2011) of CCCC Highway Consultants Co., Ltd., the "Technical Specification for Geotechnical Engineering Survey of Substations" (DLT5170-2015) of Electric Power Planning and Design Institute, the "Code for Geological Investigation of Railway Engineering" (TB10012-2019) of China Railway First Survey and Design Institute Group Co., Ltd., etc. These enterprise specifications conduct surveys by referring to the relevant regulations for filling. There are literature reports on the analysis of suspended sediment concentration based on multi-source satellite remote sensing data and water color remote sensing technology. Combining on-site investigations, the conclusion that sand mining activities exist in the high-value areas of suspended sediment concentration is found (Yang Jingxue, "Application of Multi-Source Satellite Remote Sensing Data and Water Color Remote Sensing Technology in Sand Mining Supervision of Hedi Reservoir", Guangdong Water Resources and Hydropower: 2017, 11: 42-45), or the image recognition technology is used to identify the sand mining area (Application of Image Recognition Technology Based on Deep Learning in Illegal Sand Mining Supervision by Tang Wenhua et al., 2021, 5: 108-112).

[0004] The survey methods reported in the above specifications and literature are more applicable when there is a large difference in lithology between the sand mining area and the non-sand mining area. However, it is difficult to distinguish the sand mining area when the spatial distribution regularity is not strong and the difference in geotechnical properties is small, and it is impossible to achieve the survey of the scope of the sand mining area. The small difference in geotechnical properties in the sand mining area means that the material composition of the sand mining area is similar or completely the same. There are also some sand mining areas where the pebble soil after filling after sand mining is similar or the same as the original state. Patent document CN202011293835.2 discloses a method for determining the impact range of sand mining and void areas based on the principle of grain size analysis in sedimentology. The application results of grain size analysis in distinguishing sedimentary environment types are linked to the determination of the impact range of sand mining and void areas. Based on the particle analysis data of sand layer soil samples, the grain size analysis method in sedimentology is used to comprehensively analyze the characteristics and laws of the grain size composition of sand layer soil samples, give the distribution boundary, and judge whether the source of the sand layer soil sample belongs to the non-sand mining area, the sand mining disturbance area or the sand mining area, and then infer the distribution and impact range of the sand mining and void areas. However, the method of this patent requires taking a large amount of soil samples and conducting tests, which is complicated and expensive, and is not suitable for promotion and application. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem in the prior art that it is difficult to distinguish sand mining areas with small differences in geotechnical properties and similar or completely identical material compositions, and to provide a method for surveying the scope of sand mining areas.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A sand mining area scope survey method comprises the following steps:

[0008] S1. Survey and determine the plane scope of the sand mining area in the target area, including:

[0009] S11. Collect relevant information and determine the initial plane range of the sand mining area;

[0010] S12. Re-survey the initial plane range to determine the obvious mining area;

[0011] S13, using satellite image data to determine the hidden mining area within the initial plane range;

[0012] S14, combining the obvious mining area and the hidden mining area, determining the plane range of the sand mining area in the target area;

[0013] S2. Survey and determine the mining depth of the sand mining area in the target area, including:

[0014] S21. Use the cross-section method to analyze the surface conditions of the plane range of the sand mining area before and after mining;

[0015] S22. Use geophysical methods to determine the initial lithology and initial deep mining depth changes within the plane of the sand mining area;

[0016] S23, determine the deep lithology mining depth by using the drilling and coring method according to the change of the initial deep mining depth;

[0017] S24. According to the deep lithology mining depth, the dynamic exploration method is used to verify the deep pebbles mining depth of the same lithology, and determine the mining depth of the sand mining area;

[0018] S3. Based on the mining depth and lithology differences, the plane range of the mining area in the target area is divided into four zones, namely, the water pit zone, the coarse-grained soil zone, the coarse-grained soil zone, and the mixed zone.

[0019] The technical method of the present invention proposes to separately survey the obvious mining area and the hidden mining area in the mining area to determine the plane range of the mining area, and then use the cross-section method to measure the surface and geophysical exploration to preliminarily determine the surface layer, different lithologies, and deep sand mining depths, and then use drilling and dynamic exploration to determine in detail the depth distribution range of rock and soil layers of different lithologies and the same lithology; and then conduct a zoning geological evaluation of the sand mining area.

[0020] In the present invention, an obvious mining area refers to an area with obvious mining traces after mining, such as mining pits, sump pits, etc.; a hidden mining area refers to an area with no obvious mining traces after mining, such as an area that is backfilled after mining.

[0021] Furthermore, in step S11, collecting relevant information includes: collecting a pre-mining topographic map of the target area, and determining the mining location through investigation and interviews; and determining the initial plane range of the sand mining area through the pre-mining topographic map and the investigation and interview results.

[0022] Furthermore, in step S12, the initial plane range is resurveyed using an aerial survey topographic map.

[0023] Furthermore, in step S13, multiple satellite images are used for comparative analysis to find the satellite images of the period with the largest changes, and the hidden mining areas are determined therefrom.

[0024] Furthermore, step S14 also includes combining the obvious mining area and the hidden mining area, using pit exploration to refine the plane boundary range of the mining area to obtain an increased mining area, and after further refining the plane boundary range, comprehensively determining the plane range of the sand mining area in the target area based on the obvious mining area, the hidden mining area, and the increased mining area.

[0025] Furthermore, in step S22, high-density electrical method is used for geophysical exploration, and stratification is performed according to different resistivities; then surface waves are used to measure surface wave velocities of different frequencies, to understand the relevant properties of the underground geological structure and calculate the shear wave velocity values of the corresponding rocks and soils, to determine the lithology of the initial mining area and the initial deep mining depth changes.

[0026] Furthermore, the water pit area is a water-containing area that has been mined to the bedrock surface and has very little backfill soil; the coarse-grained soil area is a backfill soil in which the coarse-grained soil content is greater than 15%, and coarse-grained soil refers to backfill soil with a particle size d greater than 60 mm; the coarse-grained and fine-grained soil area is a backfill soil in which the coarse-grained soil content is not more than 15%, mainly coarse-grained soil and fine-grained soil, coarse-grained soil refers to backfill soil with a particle size d of 0.075-60 mm and a content greater than 50%, and fine-grained soil refers to backfill soil with a particle size d less than 0.075 mm and a content not less than 50%; the mixed area is an area where coarse-grained soil, coarse-grained soil and fine-grained soil are distributed.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The survey method of the present invention first surveys the obvious mining area, hidden mining area and increased mining area in the mining area, comprehensively determines the plane range of the sand mining area by the obvious mining area, hidden mining area and increased mining area, and then uses the cross-section method surface measurement and geophysical exploration to preliminarily find out the surface layer, different lithology and deep sand mining depth respectively, and uses drilling and dynamic exploration to find out the depth distribution range of different lithology and the same lithology rock and soil layer in detail, and the method from the surface to the inside, from the bright to the dark comprehensive survey method better finds out the plane range and mining depth, comprehensive survey, method reliability, cost controllable, can accurately determine the spatial distribution of the sand mining area; at the same time, the target area sand mining area is evaluated for different district classification, and provides a reliable scientific theoretical basis for subsequent design and construction in the target area, and can effectively use different sand mining area soil bodies, reduce the foundation treatment engineering quantity, save treatment costs, and have practical engineering application value under the condition of ensuring basic safety during construction. The present invention is more accurate in the exploration of target areas where the difference in geotechnical properties is small and the sand mining areas with similar or completely identical material compositions are difficult to distinguish. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the process of the sand mining area scope survey method of the present invention;

[0030] Figure 2 Comparison chart of water level changes surveyed at different periods;

[0031] Figure 3 This is a satellite image of the largest mining area from 2013 to 2015;

[0032] Figure 4 To combine the hidden mining area with the obvious mining area and then produce a plan view of the mining area;

[0033] Figure 5 It is a schematic diagram of the pit exploration layout;

[0034] Figure 6 This is a site photo of a typical pit exploration TC01;

[0035] Figure 7It is a schematic plan view of the sand mining area in the target area;

[0036] Figure 8 It is a schematic layout diagram for the exploration of mining depth;

[0037] Figure 9 It is a field map of the SZK16 core in a typical borehole;

[0038] Figure 10 It is a schematic plan view of the sub - regions of the sand mining area in the target area.

[0039] Figure 11 It is a schematic sectional view of the sub - regions of the sand mining area in the target area. Specific implementation manners

[0040] The present invention will be further described in detail below in combination with test examples and specific implementation manners. However, it should not be understood that the scope of the above - mentioned subject matter of the present invention is limited to the following embodiments. All technologies implemented based on the content of the present invention belong to the scope of the present invention.

[0041] Embodiment 1

[0042] In this embodiment, taking the Zhangjiaba Wharf Project in Guangyuan Port as an example, the area is surveyed to determine the scope of the mining area. The project area is located in northern Sichuan, and the geomorphic type is erosional - depositional river valley geomorphology. The geomorphic unit is the riverbed and the first - order terrace on the right bank of the Jialing River in the reservoir area of the Shaxi Navigation - power Junction Project. The terrace surface elevation is 366.3 - 371.0 m, and the relative elevation difference is 4.7 m. It is 2.3 - 7.0 m higher than the current river water level (364.0 m). Due to the influence of sand mining, obvious artificial disturbance activities such as excavation and backfilling in the area have caused great damage to the original stratum structure within the area, and sand - mining pits have been locally formed. The exposed strata are mainly Quaternary Holocene artificial fill, pebble - containing silty clay, pebbles, sandy soil, and silty soil, with a general thickness of 10.8 - 17.6 m. The bedrock is mainly the siltstone and sandstone of the Lower Cretaceous Cangxi Formation (K1c). The project area is located at the intersection of the Western Sichuan Fold Belt and the Central Sichuan Fold Belt, about 6 km southeast of the Cangxi Syncline. According to the "China Seismic Ground Motion Parameter Zoning Map" (GB18306 - 2015), the basic peak acceleration of seismic ground motion at the site is 0.05 g, and the corresponding basic seismic intensity is VI degree.

[0043] According to the investigation, there is no detailed mining procedure in the sand mining process. Mining, backfilling, stacking, and waste soil are carried out at random, and temporary buildings are built at random. Due to the non-standard nature of sand mining activities, there is a great deal of irregularity in mining. At present, the sand mining area of the project is characterized by prominent irregular soil pits. Multiple excavations and backfilling during the mining process have resulted in uneven terrain at the bottom of the mining pits. Due to the traction of deep pits formed by underwater mining of sand and pebbles, the front edge of the terrace has collapsed significantly, which is different from the original landform. However, the surface material is not much different from the original landform. The existing terrain at the bottom of some pits is no longer the original terrain, making it extremely difficult to survey the plane range and depth range of the sand mining area.

[0044] S11. Collect relevant information. Collecting relevant information includes collecting the pre-mining topographic map of the target area and investigating and visiting to determine the mining location. The initial plane range of the sand mining area is determined by the pre-mining topographic map and the results of the investigation and visit. After collecting the pre-mining topographic map of the project area, the original terrace landform has changed during the investigation in the construction drawing design stage. After investigating and visiting local residents, it is learned that the sand mining site has been mining since the beginning of 2013. Sometimes mining is seen on land, sometimes mining is seen from water, sometimes the sand and gravel mined in the river are backfilled, sometimes the abandoned soil after sorting is backfilled, and sometimes the slag is sent by external vehicles to fill. Because there are piles of materials on the surface, the specific plane range and depth are unclear, but it is certain that it is larger than the existing water edge range.

[0045] S12. Resurvey the terrain to identify obvious mining areas.

[0046] In view of the landform changes, the topographic map was re-surveyed on the basis of the initial plane range. The aerial survey topographic map uses drone aerial survey technology. Obvious mining areas refer to areas with obvious mining traces after mining, such as mining pits. The results of drone surveying are used to obtain the re-surveyed topographic map using digital orthophotos. Since the project area is located in the reservoir area, the water edge elevation is basically the same during the two topographic map measurements. This time, the water edge is used for comparative analysis. Figure 2 As shown in the figure, the changes in the waterside line are mainly concentrated in the front edge frame of the wharf, the retaining wall, and the yard position close to the retaining wall. The change length is about 270m and the change area is about 17870.09m 2 .

[0047] S13. Use satellite image data to identify hidden mining areas.

[0048] On the basis of determining the terrain change segments visible on the surface, hidden mining areas are determined for other areas within the initial plane range. Hidden mining areas refer to the segments that are backfilled after mining and restored to the ground elevation. Use multiple satellite images for comparative analysis to find satellite images of periods with greater changes. The period of greater changes can be defined based on satellite image data from different regions. In this embodiment, it is found that the period of greater changes was from 2013 to 2015. During this period, areas that were excavated and then backfilled existed to determine hidden mining areas. After the hidden mining area is determined, Figure 3 As shown in the figure, it can be seen that the actual affected area of the mining area is larger than the area reflected in the topographic map on the initial plane range. The actual total affected area is about 30445.42m 2 , of which the area that cannot reflect the changes due to topographic map review ( Figure 4 The middle shaded area) is about 12143.44m 2 , accounting for 39.9% of the total area.

[0049] S14. Use pit exploration to refine the plane boundary range of the mining area to obtain an increased mining area; and comprehensively determine the plane range of the sand mining area in the target area based on the obvious mining area, the hidden mining area, and the increased mining area.

[0050] On the basis of re-surveying the topographic map to determine the obvious mining area, and determining the hidden mining area with satellite image data to preliminarily delineate the mining area, pit exploration is used to refine the plane boundary range of the mining area, taking into account the changes in the lithology of the surface sand mining area and the non-sand mining area. In this embodiment, 15 pit explorations are arranged, such as Figure 5 The geotechnical conditions of each pit are shown in Table 1. The mining area and non-mining area in Table 1 are distinguished by combining the plane range determined by the obvious mining area and the hidden mining area. According to the stratigraphic conditions revealed by the exploration pits, 11 pits reflect that there are lithological changes within the pit depth range (2.5-5.0m): the material composition of the strata revealed in the sand mining area is relatively mixed, mainly composed of a mixture of silt, silty silt, silt sand, pebbles, blocks, concrete, a small amount of construction waste, a small amount of plastic bags, etc.; 4 pits reflect that the strata revealed in the non-sand mining area are silt and silt sand on the upper part, and pebbles and gravels on the lower part, all of which are relatively pure. For example, the typical pit exploration number is TC01. Figure 6 As shown in the figure, the 0.0-1.0m section of TC01 is mainly composed of pebbles and gravels, with blocks of stone and a small amount of domestic waste such as plastic bags; the 1.0-4.0m section is mainly composed of a mixture of silt and silt sand, which is relatively pure and contains a small amount of pebbles in some places; the 4.0-5.0m section is mainly composed of a mixture of pebbles, blocks of stone, concrete and a small amount of construction waste. Therefore, TC01 can be determined as a mining backfill area.

[0051] According to the findings of the exploration pits, TC01, TC04, TC05, TC06, TC07, TC08, TC09, TC10, TC11, TC12, and TC15 can be determined as mining areas. Among them, TC15 was previously considered a non-mining area. After pit exploration, the plane range of the sand mining area was further refined to obtain the increased mining area. The plane range of the sand mining area was finally determined by combining the obvious mining area, hidden mining area, and increased mining area. Figure 7 As shown, about 34592.01m 2 The area increased by about 4578.48m compared with the satellite image data 2 , accounting for 13.2% of the total area.

[0052] Table 1 Summary of site pit exploration

[0053]

[0054] S2. Survey and determine the mining depth of the sand mining area in the target area, including:

[0055] S21. Use the cross-section method to analyze the surface conditions of the plane range of the sand mining area before and after mining.

[0056] In order to find out the damage to the surface of the area (water pit) where the terrain has obviously changed in the sand mining area, we used the cross-section method to compare and analyze the surface conditions at the same location based on the topographic maps before and after mining to determine the change in surface mining depth. This embodiment uses RTK for cross-section measurement and arranges 5 cross-section analyses, 2 vertical and 3 horizontal, as shown in Figure 8. The elevation changes in each cross section are shown in Table 2, where the change in surface depth refers to the difference between the surface depth before and after mining. By comparing Table 1, it can be seen that the ground lines re-measured after mining are all below the ground line before mining, that is, the original ground line, with a depth difference of 0.5-11.13m. The deepest is on the east side of the sand mining area, which shows that the excavation thickness of each part is uneven during the mining activity.

[0057] Table 2 Comparison of surface mining depth

[0058] Cross-section number Relationship between the original ground line and the detailed exploration ground line Variation of the surface layer depth (m) 1-1’ Below the original ground line 1.4-3.32 2-2’ Below the original ground line 1.7-3.5 3-3’ Below the original ground line 0.5-5.85 4-4’ Below the original ground line 0.8-11.13 5-5’ Below the original ground line 1.87-6.87

[0059] S22. Use geophysical methods to determine the initial lithology and initial deep mining depth changes within the plane of the sand mining area.

[0060] For different lithologies, the high-density resistivity method is used for geophysical prospecting in this case. Four test sites are mainly arranged perpendicular to the river direction, as shown in Figure 8. Stratification is carried out according to different resistivity values. Then, the surface wave velocity at different frequencies is measured by surface waves to obtain the relevant properties of the underground geological structure and calculate the corresponding values. In this embodiment, the high-density resistivity method uses a DZD-8 multi-functional full-waveform direct current resistivity instrument. The data obtained by the high-density resistivity method is inversely imaged to form a chromatogram. The model of the surface wave is MS3000, and the shear wave velocity values and compaction states of each rock and soil are obtained as shown in Table 3.

[0061] According to Appendix A of the Code for Seismic Design of Railway Engineering (GB50111-2009), the boundaries of each rock and soil layer are preliminarily determined at different positions according to different resistivity values to obtain the stratification situation; in the standard mining area, it is mainly composed of pebble-bearing silty clay, silty fine sand, silt and loose pebbles, and the original landform is mainly composed of medium-dense pebbles. The initial depth range of the mining area is obtained by dividing the plane range of the sand mining area determined in step S1.

[0062] Table 3 Shear wave velocity values of each rock and soil in the site

[0063]

[0064] S23. The core drilling method is used to determine the deep lithology mining depth according to the change of the initial deep mining depth.

[0065] Based on the preliminary determination of the deep mining depth of the sand mining area by geophysical prospecting, the core drilling method is adopted. In this embodiment, multiple positions are selected for drilling, as Figure 8 shown. Drilling is carried out at the detection points through drilling equipment to obtain multiple drill holes. The deepest pebbles are used as the reference mining boundary, and the artificial fill and silty clay are judged as the mining backfill, and the deepest pebbles are used as the initially determined original lithology. For example, the typical drill hole number is SZK16, as Figure 9 shown. According to the core results, in the section of 0-2m, it is mainly pebbles, the pebble particle size is generally 2-8cm, and the pebble content is 50-55%. In the section of 2-7.9m, it is mainly silt and pebble-bearing silt, with local interlayers of silty clay, and brown humus can be seen in the section of 6.67-7.9m. In the section of 7.9-10.3m, it is pebbles. Therefore, for this place, the sand mining depth can be judged as 7.9m from the lithology. The deep lithology mining depth is determined according to the results of the core drilling method at different positions.

[0066] S24. The dynamic sounding method is used to determine the deep pebble mining depth according to the deep lithology mining depth, and the mining depth of the sand mining area is determined.

[0067] For the pebbles in the sand mining area, the dynamic penetration test is used to classify the density of the pebbles on the basis of the preliminary determination of the mining depth by geophysical exploration. The pebbles of the same lithology can be distinguished and the mining depth can be further determined. Since the original landform is a terrace, the density of the pebbles is relatively high, while the mining area is a recent backfill with a low density. The dynamic penetration test instrument is a cone dynamic penetration test. According to the results of the on-site dynamic penetration test as shown in Table 4, the artificial filling (pebbles) in the sand mining area has an uneven distribution of fill density due to differences in the content of floating pebbles and particle size. The dynamic penetration test number is mostly between 1.93 and 9.28. According to GB50021-2009 Geotechnical Engineering Investigation Code, its overall structure is mainly loose to slightly dense. The dynamic penetration test number of pebbles in the original structure is mostly between 10.5 and 27.24, which is a medium-dense state.

[0068] Table 4N 63.5 In-situ test statistical results table

[0069]

[0070] Based on the results of geophysical exploration, drilling and dynamic exploration, it was finally confirmed that the mining depth of the sand mining area was 1.80 to 13.12 meters, with an average thickness of about 7.5 meters.

[0071] S3. According to the differences in the sand mining area, core and plane range, the mining area is divided into four areas. The water pit area is a water-containing area where the mining reaches the bedrock surface and there is very little backfill soil; the coarse-grained soil area is a backfill soil with a coarse-grained soil content of more than 15%, and coarse-grained soil refers to backfill soil with a particle size d greater than 60mm; the coarse-grained soil area is a backfill soil with a coarse-grained soil content of no more than 15%, mainly coarse-grained soil and fine-grained soil. Coarse-grained soil refers to backfill soil with a particle size d of 0.075-60mm and a content of more than 50%, and fine-grained soil refers to backfill soil with a particle size d less than 0.075mm and a content of not less than 50%; the mixed area is an area where coarse-grained soil, coarse-grained soil and fine-grained soil are distributed. After the above comprehensive means of investigation, it was found that the plane area of the sand mining area is about 34592.01m 2 The mining depth of the sand mining area is 1.80~13.12m. Figure 10 The situation of each district is as follows:

[0072] Area 1 is a water pit area, with a sand excavation depth of 10.61 to 13.12 m. It is mined to the bedrock surface, with very little backfill soil and a large amount of water. The area is about 17870.09 m 2 , accounting for 51.85% of the entire sand mining area.

[0073] Area 2 is a coarse-grained soil area, with a sand mining depth of 5.07 to 8.47 m. The lithology of the sand mining backfill soil is mainly gravel, with a loose to slightly dense structure, and an area of about 7115.69 m 2 , accounting for 20.57% of the entire sand mining area.

[0074] Area 3 is the area of fine and coarse grained soil. The sand excavation depth is 1.80 - 8.10 m. The lithology of the sand excavation and backfill soil is mainly a mixture of silt, silty sand with gravel, cobblestone, concrete, a small amount of construction waste, a small amount of plastic bags, etc. The structure is loose to slightly dense, and the area is about 2476.03 m 2 , accounting for 7.16% of the entire sand excavation area.

[0075] Area 4 is the mixed area: The sand excavation depth is mostly 3.85 - 10.48 m. The lithology after sand excavation and backfill is mainly organic silt, silty sand, silt with pebbles, gravel, with a loose to slightly dense structure, and the area is about 7130.2 m 2 , accounting for 20.42% of the entire sand excavation area.

[0076] On the basis of the engineering geological evaluation of each area, reasonably dispose and utilize the soil in the mining area, verify the bearing capacity with load tests, and give suggestions on the selection of bearing strata for each area.

[0077] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for surveying the scope of a sand mining area, characterized in that, The following steps are involved: S1. Survey and determine the plane scope of the sand mining area in the target area, including: S11. Collect relevant information and determine the initial plane range of the sand mining area; S12. Re-survey the initial plane range to determine the obvious mining area; S13, using satellite image data to determine the hidden mining area within the initial plane range; S14, combining the obvious mining area and the hidden mining area, determining the plane range of the sand mining area in the target area; S2. Survey and determine the mining depth of the sand mining area in the target area, including: S21. Use the cross-section method to analyze the surface conditions of the plane range of the sand mining area before and after mining; S22. Use geophysical methods to determine the initial lithology and initial deep mining depth changes within the plane of the sand mining area; S23, determine the deep lithology mining depth by using the drilling and coring method according to the change of the initial deep mining depth; S24. According to the deep lithology mining depth, the dynamic exploration method is used to verify the deep pebbles mining depth of the same lithology, and determine the mining depth of the sand mining area; S3. Based on the mining depth and lithology differences, the plane range of the mining area in the target area is divided into four zones, namely, the water pit zone, the coarse-grained soil zone, the coarse-grained soil zone, and the mixed zone.

2. The sand mining area scope survey method according to claim 1, wherein In S11, collecting relevant information includes: collecting a pre-mining topographic map of the target area, and determining the mining location through investigation and interviews; and determining the initial plane range of the sand mining area through the pre-mining topographic map and the investigation and interview results.

3. The sand mining area range survey method according to claim 1, characterized in that The initial plane range was resurveyed using aerial topographic maps.

4. The sand mining area range survey method according to claim 1, characterized in that By using multiple satellite images for comparative analysis, we can find the satellite images during the periods of greater changes and identify the hidden mining areas.

5. The sand mining area scope survey method according to any one of claims 1-4, characterized in that Step S14 also includes combining the obvious mining area and the hidden mining area, using pit exploration to refine the plane boundary range of the mining area to obtain an increased mining area; and comprehensively determining the plane range of the sand mining area in the target area based on the obvious mining area, the hidden mining area, and the increased mining area.

6. The sand mining area range survey method according to claim 1, characterized in that, In step S22, high-density electrical method is used for geophysical prospecting, and stratification is performed according to different resistivities; then surface waves are used to measure surface wave velocities of different frequencies, understand the relevant properties of underground geological structures and calculate the shear wave velocity values of the corresponding rocks and soils, and determine the lithology of the initial mining area and the initial deep mining depth changes.

7. The sand mining area range exploration method according to claim 1, characterized in that, The water pit area is a water-containing area that has been mined to the bedrock surface and has very little backfill soil; the coarse-grained soil area is an area where the coarse-grained soil content in the backfill soil is greater than 15%, and coarse-grained soil refers to backfill soil with a particle size d greater than 60 mm; the coarse-grained and fine-grained soil area is an area where the coarse-grained soil content in the backfill soil is not more than 15%, and is mainly coarse-grained soil and fine-grained soil. Coarse-grained soil refers to backfill soil with a particle size d of 0.075-60 mm and a content of more than 50% of particles, and fine-grained soil refers to backfill soil with a particle size d of less than 0.075 mm and a content of not less than 50% of particles; the mixed area is an area where coarse-grained soil, coarse-grained soil and fine-grained soil are distributed.

Images