Construction method for rockfill dam fine particle rockfill content control filling

Abstract

The application discloses a construction method for content control filling of fine particle rockfill of a rockfill dam, and belongs to the technical field of design and construction of hydraulic and hydroelectric engineering buildings. The construction method can effectively improve the filling quality of the rockfill dam, and the particle size of the rockfill of each part of the rockfill dam meets the requirements. The construction method comprises the following steps: firstly, the rockfill dam body and the rockfill yard are divided into zones; then, the rockfill mining and the rockfill filling are carried out in a one-to-one correspondence according to the rockfill dam body zoning and the rockfill yard zoning; the quality of each rockfill dam layer is detected; the fine particles with excessive content are removed from the rockfill of the outer area of the rockfill dam body and / or the filling area of the upper part of the rockfill dam body in the rockfill transfer process; and the surface broken fine powder layer exceeding the standard after the paving and rolling of each filling layer are scraped off before the filling of the next layer of rockfill.

Description

Technical Field

[0001] This invention relates to a construction method, and more particularly to a construction method for controlling the content of fine-particle rockfill in rockfill dams, belonging to the field of design and construction technology of water conservancy and hydropower engineering structures. Background Technology

[0002] Rockfill dams, a type of earth-rock dam, possess advantages such as strong adaptability to terrain and geological conditions, local material sourcing, low cost, and high stability, making them a widely used dam type worldwide. The main filling material for rockfill dams is rockfill aggregate. Rockfill aggregate is a granular material formed by the intermingling of rock particles of different sizes. In high dam projects, it is often required to possess engineering characteristics such as high permeability, good compaction performance, high shear strength, high bearing capacity, and low deformation. The particle size range of rockfill aggregate for dam construction is relatively large, with the largest particle size reaching 1000mm, while the smallest particles are less than 0.075mm, classifying it as a typical wide-gradation granular material. The content of fine particles significantly affects the mechanical properties of rockfill aggregate; excessive content can affect the permeability, strength, and deformation indices of the rockfill filling, thereby causing problems with dam seepage stability, slope stability, and deformation stability. Relevant specifications limit the continuity of rockfill gradation and the content of fine particles, requiring that the content of particles smaller than 5mm not exceed 30%, and the content of particles smaller than 0.075mm not exceed 5%, with even stricter requirements for high dam projects.

[0003] With the accelerated construction of high dams and reservoirs in China, a number of 300m-class ultra-high rockfill dams, including Shuangjiangkou, Rumei, Gushui, Lawa, and Dashixia, are under construction or planned. The rockfill material for dam construction is generally mined by blasting. From the perspective of dam deformation control and deformation coordination, the gradation of the blasted material must meet design requirements. From the perspectives of investment, environmental protection, and water conservation, the excavated material in the quarry and project area must be used to its fullest potential, minimizing waste. However, due to the complex and variable engineering geological conditions and the uncertainty of blasting, the excavated and blasted rock often contains a high content of fine particles, and conventional methods are insufficient to economically and efficiently remove excess fine particles. During the paving process, the more efficient advancing method is often used, which is more prone to particle segregation, resulting in the concentration and uneven distribution of fine particles. Layered filling and vibratory compaction in the rockfill area can easily lead to particle breakage, and in severe cases, the formation of a hardened fine-grained layer on the surface. For example, the lithology of a certain ultra-high rockfill dam's quarry is complex, with well-developed joints and fissures, and the fine particle content of the blasted material exceeds 30%. After the rockfill is compacted, a surface layer of about 10 cm of excessive fine powder forms, posing a significant challenge to the project construction. The high and uneven distribution of fine particles in the rockfill has become a key factor restricting the dam's filling quality, construction period, and investment control.

[0004] Rockfill dam construction is characterized by its large size, complex procedures, and long construction time. It involves numerous scenarios and construction stages, including material extraction, paving, compaction, and testing. Considering investment and efficiency, accurately controlling the fine particle content over the entire process and on a large scale is extremely difficult and involves many uncertainties. Previously, there were no mature technologies or control requirements for fine particle control in the construction of high rockfill dams. Current design and construction specifications only require that the fine particle content meet certain requirements and that the gradation be continuous. However, specific construction measures to achieve this goal still mainly rely on the control of blasting parameters during mining. For some rockfill quarries with poor lithology, blasting parameter control cannot solve the problem of high fine particle content in the blasted material, and there are no mature methods to deal with particle breakage and fine particle concentration during the filling process. Existing technologies are no longer sufficient to meet practical needs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a construction method for controlling the content of fine-particle rockfill in rockfill dams, which can effectively improve the filling quality of rockfill dams and ensure that the particle size of the rockfill material in each part of the rockfill dam meets the requirements.

[0006] The technical solution adopted to solve the above-mentioned technical problems is: a construction method for controlling the fine particle content of rockfill material in rockfill dams, characterized in that: the construction method first divides the rockfill dam body and the rockfill material yard into zones, then carries out rockfill material mining and filling according to the corresponding zones of the rockfill dam body and the rockfill material yard, and conducts fine particle content testing and compaction index testing on each filled rockfill dam layer in a timely manner according to the filling sequence, finally obtaining a rockfill fill body that meets the filling requirements of rockfill dams. During the transportation of rockfill, at least the fine particles with excessive content in the outer area of ​​the rockfill dam body and / or the upper filling area of ​​the rockfill dam body should be removed. During the layer-by-layer filling of the dam body, the surface of each filling layer after spreading and compaction should be scraped off before the next layer of rockfill is filled.

[0007] Furthermore, when dividing the rockfill dam body into zones, based on the technical requirements for rockfill dam construction and the characteristics of the rockfill material extracted from the quarry, the dam body is divided into three zones from the outside to the inside along its length, with the bottom center as the reference. Similarly, when dividing the rockfill quarry into zones, based on geological survey information and the technical requirements for rockfill dam construction, the quarry is divided into three zones corresponding to the dam body zones: Rockfill Material I, Rockfill Material II, and Rockfill Material III. During the rockfill dam construction, the rockfill material extracted from Rockfill Material I, Rockfill Material II, and Rockfill Material III corresponds to the Rockfill Material I, Rockfill Material II, and Rockfill Material III zones used to fill the rockfill dam body, respectively. During the rockfill material transfer process, at least the fine particles exceeding the standard content in the rockfill material extracted from Rockfill Material I are initially removed.

[0008] The preferred approach to the above scheme is that the geological survey information used to zon the rockfill yard should at least include the rock mass conditions of the working face of each rockfill area, and the rockfill dam filling requirements should at least include the design strength and gradation requirements of the rockfill material for each rockfill area of ​​the rockfill dam. The specific zoning process is as follows: Based on the identification of the material source, the area with intact, high-strength rock mass at the working face, relatively homogeneous lithology, and inferred no significant changes in internal lithology was designated as rockfill mining area I. Based on the development of joints and fissures, the degree of unloading, and the distribution of lithological types, combined with the stringency of fine-grain control, rockfill mining areas II and III were further designated. Each rockfill mining area is independently mined using on-site blasting. The amount of explosives used and the spacing between blast holes in each rockfill mining area are determined by testing based on the design gradation requirements of each rockfill.

[0009] Furthermore, the source identification was conducted according to the following steps and requirements: Areas with high rock strength, moderate particle size, and good gradation in riprap are identified as usable material, while areas with low rock strength, excessively small particle size, high fine powder content, or containing mud and sand impurities are identified as unusable material. During the assessment, the strength of the riprap is determined based on its lithology and the results of previous tests; or it is determined by manual observation on-site using tools and engineering experience; and further determined by on-site sampling and laboratory testing; particle size, gradation and fine particle content are determined on-site and in conjunction with the prescribed particle sieving tests. Based on the fine particle content, usable materials are further divided into rubble material I, rubble material II, and rubble material III.

[0010] The preferred method of the above scheme is that the removal of fine particles with excessive content during the transfer of rockfill is achieved by setting a filter plate with sieve holes at the bottom of the loading box of the transport equipment, and then removing some fine particles by sieving and washing them into the double-layer bottom plate structure below the filter plate through bumps and water flow from the high-pressure water injection point during the transport of the equipment.

[0011] Furthermore, the removal of excessive fine particles during the transport of rockfill also includes setting the excavator's hopper as a grid hopper, and using a shaking motion to initially screen out some of the excessive fine particles during the loading of the rockfill into the loading box.

[0012] The preferred embodiment of the above scheme is that the diameter of the filter holes on the filter plate and the arc-shaped bottom plate of the grid hopper is 5 to 10 cm, the distance between the filter plate and the bottom of the loading box is not less than 10 cm, and the number of times the excavator shakes its arm is not less than 3.

[0013] Furthermore, when filling the rockfill in each rockfill area, a mixed paving method of advancing and retreating is adopted. After paving, the rockfill is leveled by bulldozers and / or excavators, and then compacted and filled according to the specified compaction parameters. Finally, bulldozers are used to remove the broken fine powder layer on the surface and roughen the surface.

[0014] The preferred method of the above scheme is that the compaction parameters include the number of compaction passes, the driving route of the compaction machinery and the speed; when determining the compaction driving route, compaction is carried out along a straight route, and the compaction range between two adjacent compaction lines overlaps by at least 10cm; when scraping off the surface broken fine powder layer, the scraping operation is carried out 1-2 times by a bulldozer.

[0015] The beneficial effects of this invention are: the above-mentioned technical solution provided by this application makes full use of the characteristics of the engineering dam body itself and the significant differences in the requirements of relevant specifications for different parts of the dam body. Combined with the distribution characteristics of the material yard itself, it carries out zoned mining, zoned identification, marking and transportation, zoned spreading and filling. After filling, the surface layer of excessive fine powder is appropriately scraped off. Thus, without significantly increasing the construction procedures and investment costs, the goal of making full use of materials, zoned utilization, appropriate treatment and quality control can be achieved. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the partitioned structure of the rockfill dam involved in the construction method for controlling the content of fine-particle rockfill material in the rockfill dam, as described in this invention. Figure 2 This is a schematic diagram of the filter plate involved in the construction method of controlling the content of fine-particle rockfill in rockfill dams according to the present invention. Figure 3This is a schematic diagram of the structure of the grid hopper involved in the construction method for controlling the content of fine-particle rockfill in rockfill dams according to the present invention. Figure 4 This is a flowchart of the construction method for controlling the content of fine-particle rockfill in rockfill dams according to the present invention.

[0017] The markings in the diagram are: Rockfill I 1, Rockfill II 2, Rockfill III 3, Filter plate 4, Grating hopper 5, Filter holes 6. Detailed Implementation

[0018] like Figures 1-4 This invention provides a construction method for controlling the fine particle content of rockfill material in rockfill dams, which effectively improves the filling quality and ensures that the particle size of the rockfill material in each part of the dam meets the requirements. The method first divides the rockfill dam body and rockfill material yard into zones. Then, rockfill material mining and filling are carried out according to the corresponding zones of the dam body and rockfill material yard. Fine particle content and compaction index tests are performed on each layer of the rockfill dam according to the filling sequence, ultimately obtaining a rockfill filling body that meets the requirements for rockfill dam construction. During the transportation of rockfill, at least the outer area of ​​the rockfill dam body and / or the upper filling area of ​​the rockfill dam body should be cleaned of excessive fine particles. Furthermore, during the layer-by-layer filling of the dam body, the surface layer of excessive fine powder after each filling layer is laid and compacted should be scraped off before the next layer of rockfill is added. The technical solution provided in this application fully utilizes the characteristics of the dam body itself and the significant differences in requirements for different parts of the dam body according to relevant specifications. Combined with the distribution characteristics of the material yard, it implements zoned mining, zoned identification, marked transportation, zoned laying and filling. After filling, the surface layer of excessive fine particles and powder is appropriately scraped off. Thus, without significantly increasing construction procedures and investment costs, the goal of maximizing material utilization, zoned use, appropriate treatment, and quality control is achieved. In summary, the core of the technical solution of this application is zoned mining and zoned filling, and the removal of excessive fine particles during transportation after mining and the timely removal of excessive fine powder layers during filling, thereby achieving the goal of improving the quality of the rockfill dam body without significantly increasing construction procedures and investment costs.

[0019] Based on relevant industry regulations and the physical and chemical properties of the rockfill dam itself, this application divides the rockfill dam body into three zones according to the technical requirements for rockfill dam construction and the characteristics of the rockfill material extracted from the dam. Along the dam length, with the bottom center of the dam body as the reference, the zones are divided sequentially from the outside in: Rockfill I filling zone 1, Rockfill II filling zone 2, and Rockfill III filling zone 3. Similarly, when dividing the rockfill dam, based on geological survey information and the technical requirements for rockfill dam construction, the rockfill dam is divided into Rockfill I mining zone, Rockfill II mining zone, and Rockfill III mining zone, corresponding to the dam body zones. During rockfill dam construction, the rockfill material extracted from Rockfill I mining zone, Rockfill II mining zone, and Rockfill III mining zone corresponds to Rockfill I filling zone 1, Rockfill II filling zone 2, and Rockfill III filling zone 3, respectively, for filling the rockfill dam body. During the transportation of the rockfill material, fine particles exceeding the particle size limit in the rockfill material extracted from Rockfill I mining zone are appropriately removed. Accordingly, when dividing the rockfill yard into zones, the geological survey information used for zoning the rockfill yard shall at least include the rock mass conditions of the working face of each rockfill zone, and the technical requirements for rockfill dam construction shall at least include the design strength and gradation requirements of the rockfill material for each rockfill zone of the rockfill dam. The specific zoning process is as follows: Based on the identification of the material source, the area with intact, high-strength rock mass at the working face, relatively homogeneous lithology, and inferred no significant changes in internal lithology was designated as rockfill mining area I. Based on the development of joints and fissures, the degree of unloading, and the distribution of lithological types, combined with the stringency of fine-grain control, rockfill mining areas II and III were further designated. Each quarry area is independently quarried using on-site blasting. The explosive dosage and spacing between blast holes for each quarry are determined through testing based on the design gradation requirements of each quarry. The specific procedures for source identification are as follows: Areas with high rock strength, moderate particle size, and good gradation in riprap are identified as usable material, while areas with low rock strength, excessively small particle size, high fine powder content, or containing mud and sand impurities are identified as unusable material. During the assessment, the strength of the riprap is determined based on its lithology and the results of previous tests; or it is determined by manual observation on-site using tools and engineering experience; and further determined by on-site sampling and laboratory testing; particle size, gradation, and fine particle content are determined by on-site observation and the prescribed particle sieving test. Based on the content of fine particles, the materials are further divided into rubble material I, rubble material II, and rubble material III.

[0020] To control the quality of the rockfill during transportation without significantly increasing the number of processes and investment costs, this application removes oversized fine particles during the rockfill transfer process by installing a filter plate 4 with sieve holes at the bottom of the loading box of the transport equipment. Then, during transport, the fine particles are screened out and washed into the double-layer bottom plate structure below the filter plate by bumping and high-pressure water flushing. The removal of oversized fine particles during rockfill transfer also includes using an excavator hopper as a grid hopper 5. During the loading of the rockfill into the loading box through the grid hopper 5, a shaking motion is used to initially screen out some of the oversized fine particles.

[0021] The diameter of the filter holes 6 set on the filter plate 4 and the arc-shaped bottom plate of the grid hopper is 5-10cm. The distance between the filter plate 4 and the bottom of the loading box is not less than 10cm. The number of times the excavator shakes its arm is not less than 3.

[0022] Furthermore, as an indispensable part of dam quality control during the filling process, this application employs a mixed paving method of advancing and retreating when filling the rockfill material in each rockfill area. After paving, the surface is leveled using bulldozers and / or excavators, and then compacted according to the specified compaction parameters. Finally, bulldozers are used to remove the surface layer of broken fine powder and roughen the surface. The compaction parameters include the number of compaction passes, the driving route of the compaction machinery, and the speed. When determining the compaction driving route, compaction is carried out along a straight route, and the compaction range between adjacent rows overlaps by at least 10 cm. When scraping off the surface layer of broken fine powder, bulldozers are used for 1-2 scraping operations.

[0023] In summary, the technical solution provided in this application also has the following advantages: 1. The excavator was modified with a grid bucket and applied to the fine particle screening of rockfill material in rockfill dams, realizing efficient and feasible fine particle screening construction for large-scale rockfill materials.

[0024] 2. The conventional single method of paving stone has been optimized, reducing the phenomenon of concentrated distribution of fine particles and further improving the reliability of the gradation of paved stone.

[0025] 3. A systematic scraping process was carried out to remove the fine powder layer formed by compaction on the surface of the riprap, which improved the quality of the riprap filling.

[0026] 4. The complete set of technologies for fine particle control during large-scale rockfill mining and filling was improved and successfully applied. The fine particle content and compaction index were tested, verifying the reliability of the proposed method.

[0027] Example 1 The technical problem to be solved by the present invention is to provide a complete construction method that can effectively control the fine particles during loading and watering of quarry stockpiles when the fine particle content is too high, ensure uniform spreading of fine particles during stockpiling, and effectively remove the surface broken layer formed during stockpiling compaction, so as to ensure that the gradation of stockpiling meets the design requirements.

[0028] The technical solution adopted to solve the above-mentioned technical problems is as follows: based on the functional requirements of the dam body, the dam rockfill is divided into rockfill zone I, rockfill zone II and rockfill zone III, with corresponding requirements for fine particle content of strict, moderate and lenient, respectively, and different technical requirements are proposed for each.

[0029] A construction method for controlling the fine particle content during the loading, transportation, water addition, and filling of rockfill materials, comprising the following steps: S1. This mainly includes zoned mining and material source identification. Based on the rock mass conditions of the dam's rockfill zones and various areas of the quarry, the mining areas for rockfill material I, II, and III are initially designated; blasting is then carried out after the mining zones are designated. After the blasting of each blasting unit in the rockfill quarry is completed, the owner, design, supervision, and construction parties are organized to conduct a material source identification on-site, identifying usable and unusable materials. Based on the characteristics of usable materials, the areas used for dam rockfill material zones I, II, and III are delineated. The type of rockfill material to be mined in the next blasting unit is then designated based on the rock mass conditions at the working face.

[0030] S2. Supervise and control the quality of each process of loading and transporting riprap in each zone, mainly including the loading and watering of riprap.

[0031] S3. Supervise and control the quality of each process in the construction of riprap filling, mainly including the process of marking the riprap zones, laying riprap, leveling, compacting and filling, and scraping off the fine powder layer after compaction.

[0032] S4. After the filling is completed, conduct permeability and porosity tests on the riprap.

[0033] In step S1: The zonal mining of rockfill is mainly determined based on the rock mass conditions at the working face, combined with the zonal mining of rockfill in the dam body and the design strength and gradation requirements of the rockfill in each zonal area.

[0034] Zoned mining needs to be carried out in conjunction with the identification of material sources. The zone is initially designated as the type of rockfill to be mined. The rock face is intact, has high strength, and the lithology is relatively homogeneous with no obvious changes in internal lithology, which is designated as rockfill mining zone I. Based on the development of joints and fissures, the degree of unloading, the distribution of lithology types, and the strictness of fine particle control, rockfill mining zones II and III are further designated.

[0035] Once the mining zones I, II, and III of the rockfill are designated, blasting mining can commence. The blasting parameters, such as the amount of explosives used and the spacing between blast holes, for each zone should be determined through testing based on the design gradation requirements of each rockfill.

[0036] The final determination of the rockfill type is based on the identification of the source material. The source material identification is as follows: areas with high rock strength, moderate particle size and good gradation are identified as usable material, while areas with low rock strength, excessively small particle size, high fine powder content or impurities such as mud and sand are identified as unusable material.

[0037] During the assessment, the strength of the riprap blocks can be determined based on their lithology and the results of previous tests; alternatively, it can be assessed on-site by tapping with tools and combining this with engineering experience through manual observation; if necessary, samples can be taken for supplementary laboratory testing. Particle size, gradation, and fine particle content are determined through on-site observation combined with necessary particle sieving tests.

[0038] Based on the content of fine particles, the materials are further divided into rubble material I, rubble material II, and rubble material III.

[0039] After the source of materials is identified, triangular flags are used to separate useful materials from useless materials, and useless materials are promptly transported to the designated storage area.

[0040] The material handling areas are also demarcated using triangular flags to mark the areas of Rockfill Material I, Rockfill Material II, and Rockfill Material III. Different colored flags are used for identification, clearly indicating "Rockfill Material I," "Rockfill Material II," and "Rockfill Material III" respectively, ensuring the markings are prominent and intuitive. This facilitates joint control of material quality among all participating parties.

[0041] In step S2: The equipment for transporting the rubble is "modified excavators" and "modified dump trucks". Each of the three rubble areas, namely rubble I, rubble II and rubble III, is equipped with dedicated transport equipment, and their respective construction is carried out without interference from each other.

[0042] "Modified excavator" refers to the modification of the excavator grab bucket used for loading stone into a grid bucket with perforations.

[0043] "Modified dump truck" refers to a truck bed structure where an additional steel plate is welded onto the original bed, creating a "double-layer bed structure" with a 10cm gap between the two layers. Ribs are installed along the vehicle's direction at the bottom of the welded layer for reinforcement. These ribs are welded to both the bed floor and the steel plate layer on both sides, providing support. The ribs are spaced 1m apart. The ribs have perforations.

[0044] The steel plate layer installed at the bottom of the carriage has holes arranged at appropriate intervals to filter fine particles and separate them from the piled stones.

[0045] A long strip-shaped fine particle storage box is welded at the rear of the carriage along the width of the carriage. The storage box is connected to the middle space of the above-mentioned "double-layer bottom plate structure". During unloading, the filtered fine particles can slide into the storage box.

[0046] A valve is installed at the bottom of the storage box. When the storage box is full, the valve is opened at a designated location to unload the contents.

[0047] The "modified dump trucks" all have prominent signs on their front indicating "Rock Material I", "Rock Material II" or "Rock Material III", indicating the type of rock material being transported. They are directed to the corresponding rock material section marked with colored flags to load materials according to the type of sign.

[0048] When loading materials in each rockfill area, the drivers of the "modified excavators" must pay attention to the license plate markings of the vehicles coming to load materials. If the markings do not match the type of rockfill material in the area, the vehicles should be returned and no materials should be loaded.

[0049] Quality inspectors were assigned to the site to manage and supervise the orderly construction of each rockfill section in accordance with the above requirements, ensuring that no mistakes occurred.

[0050] Rockfill material I is loaded into a perforated grid bin using a modified excavator, shaken a specified number of times, and then loaded onto trucks. Rockfill materials II and III are loaded directly onto trucks using a modified excavator without shaking, which to some extent removes fine particles while improving efficiency.

[0051] The construction method for fine particle screening of riprap is as follows: the excavator first fills the grating bucket with riprap, then continuously shakes the boom to allow fine particles to pass through the grating bucket's mesh for screening and filtration. The remaining riprap in the grating bucket is then loaded onto trucks and transported to the dam for filling. The modified grating bucket is filled to approximately 80% of its capacity to prevent riprap from scattering during the excavator's boom-shaking screening process.

[0052] The size of the mesh and the spacing between rows of the excavator's modified grid bucket, as well as the amplitude and frequency of the excavator's boom shaking, need to be determined based on the actual characteristics of the rockfill material and on-site screening and loading tests to ensure that the gradation of the rockfill material after screening and loading is within the design range.

[0053] Once the amplitude and number of excavator boom swings are determined, the operation will proceed accordingly, with on-site quality inspectors supervising whether the driver loads materials as required.

[0054] Monitoring facilities were set up on site to monitor the screening of the rockfill material and to monitor whether the construction procedures in the entire rockfill area were carried out in an orderly manner according to the specific division of labor.

[0055] The cargo boxes of the "modified dump trucks" are all equipped with automated canopies. After loading is completed, the canopies are opened to cover the piled stones and prevent them from scattering and being contaminated by dust.

[0056] High-pressure water injection points are set up during vehicle transportation to fully add water to the rockfill to improve compaction performance, while further washing fine particles into the "double-layer bottom plate structure" to reduce the fine particle content of the rockfill on the dam.

[0057] In step S3: The fill surface of the rockfill area is marked with white lime to delineate the zones for rockfill material I, rockfill material II, and rockfill material III. When dump trucks transport rockfill material to the rockfill area, they drive to the corresponding rockfill zone according to the type of rockfill material being transported.

[0058] Quality inspectors must be assigned to the rockfill area to supervise the delivery of rockfill materials to the corresponding rockfill zone. Vehicles without labels or those not delivering the rockfill material according to the label should not be accepted.

[0059] When unloading the rockfill, a combination of advancing and retreating methods is used for spreading, and bulldozers and excavators are used to level the rockfill and disperse any locally concentrated fine particles.

[0060] During the laying and leveling of riprap, the thickness of the riprap must be controlled to meet the design requirements.

[0061] After the material is laid and leveled to the designed compaction thickness, compaction and filling can be carried out according to the designed compaction parameters. The driving route, speed and number of compaction passes of the compaction machinery are monitored and fed back to the monitoring data center in real time as the basis for the assessment of compaction quality.

[0062] After compaction, a bulldozer is used to scrape off the broken fine powder layer on the surface, which also roughens the filling surface.

[0063] Before the bulldozer scrapes away fine powder, the route should be planned reasonably to ensure that the route is as straight as possible and the construction is convenient. At the same time, the scraping range between two adjacent driving lines should overlap by at least 10cm to avoid omissions in the construction of intersecting parts.

[0064] The scraped fine powder should be collected and transported to a designated disposal site. The location for collecting the fine powder should be determined based on the fine powder content and the size of the bulldozer blade. It is important to avoid the bulldozer blade being filled with fine powder before it reaches the collection point.

[0065] The number of times the fine powder is scraped off is 1 to 2 times, depending on the actual effect of the fine powder scraping, and shall be determined by the participating parties through discussion.

[0066] In step S4: The quality inspection of the compacted rockfill includes testing for fine particle content and compaction index. If the compaction index meets the design requirements but the fine particle content does not, targeted local excavation or secondary scraping should be carried out. If the compaction index does not meet the design requirements, targeted re-rolling should be carried out, and the surface fine powder layer should be scraped off after compaction. If both meet the requirements, the next layer can be filled according to the above process.

Claims

1. A construction method for controlling the content of fine-particle rockfill in rockfill dams, characterized in that: The construction method involves first dividing the rockfill dam body and rockfill material yard into zones, then mining and filling the rockfill material according to each zone, and conducting fine particle content and compaction index tests on each layer of the rockfill dam as needed, based on the filling sequence. Finally, a rockfill fill body that meets the requirements for rockfill dam construction is obtained. During the transportation of rockfill, at least the fine particles with excessive content in the outer area of ​​the rockfill dam body and / or the upper filling area of ​​the rockfill dam body should be removed. During the layer-by-layer filling of the dam body, the surface of each filling layer after spreading and compaction should be scraped off before the next layer of rockfill is filled.

2. The construction method for controlling the content of fine-particle rockfill in rockfill dams according to claim 1, characterized in that: When dividing the rockfill dam body into zones, based on the technical requirements for rockfill dam construction and the characteristics of the rockfill material mined from the quarry, the dam body is divided into rockfill I filling zone (1), rockfill II filling zone (2), and rockfill III filling zone (3) from the outside to the inside along the dam length with the bottom center of the dam body as the reference. When dividing the rockfill material quarry into zones, based on geological survey information and the technical requirements for rockfill dam construction, the rockfill material quarry is divided into rockfill I mining zone, rockfill II mining zone, and rockfill III mining zone corresponding to the dam body zones. During the rockfill dam construction, the rockfill material mined from rockfill I mining zone, rockfill II mining zone, and rockfill III mining zone corresponds to the rockfill I filling zone (1), rockfill II filling zone (2), and rockfill III filling zone (3) used to fill the rockfill dam body, respectively. During the rockfill material transfer process, at least the fine particles with excessive content in the rockfill material mined from rockfill I mining zone are initially removed.

3. The construction method for controlling the content of fine-particle rockfill in rockfill dams according to claim 2, characterized in that: The geological survey information used to zonify the rockfill material yard includes at least the rock mass conditions of the working face of each rockfill area. The dam construction requirements include at least the design strength and gradation requirements of the rockfill material for each rockfill area. The specific zoning process is as follows: Based on the identification of the material source, the area with intact, high-strength rock mass at the working face, relatively homogeneous lithology, and inferred no significant changes in internal lithology was designated as rockfill mining area I. Based on the development of joints and fissures, the degree of unloading, and the distribution of lithological types, combined with the stringency of fine-grain control, rockfill mining areas II and III were further designated. Each rockfill mining area is independently mined using on-site blasting. The amount of explosives used and the spacing between blast holes in each rockfill mining area are determined by testing based on the design gradation requirements of each rockfill.

4. The construction method for controlling the content of fine-particle rockfill in rockfill dams according to claim 3, characterized in that: Source identification is conducted according to the following steps and requirements. Areas with high rock strength, moderate particle size, and good gradation in riprap are identified as usable material, while areas with low rock strength, excessively small particle size, high fine powder content, or containing mud and sand impurities are identified as unusable material. During the assessment, the strength of the riprap is determined based on its lithology and the results of previous tests; or it is determined by manual observation on-site using tools and engineering experience; and further determined by on-site sampling and laboratory testing; particle size, gradation and fine particle content are determined on-site and in conjunction with the prescribed particle sieving tests. Based on the fine particle content, usable materials are further divided into rubble material I, rubble material II, and rubble material III.

5. The construction method for controlling the content of fine-particle rockfill in rockfill dams according to claim 2, 3, or 4, characterized in that: During the transfer of riprap, the fine particles with excessive content are removed by setting a filter plate (4) with sieve holes at the bottom of the loading box of the transport equipment. Then, during the transport of the equipment, some fine particles are screened out and washed into the double-layer bottom plate structure below the filter plate by the bumps and the water flow from the high-pressure water injection point.

6. The construction method for controlling the content of fine-particle rockfill in rockfill dams according to claim 5, characterized in that: The removal of fine particles with excessive content during the transfer of rockfill also includes setting the excavator's hopper as a grid hopper (5), and performing a preliminary screening by shaking the boom during the process of loading the rockfill into the loading box through the grid hopper (5) to remove some of the fine particles with excessive content.

7. The construction method for controlling the content of fine-particle rockfill in rockfill dams according to claim 6, characterized in that: The diameter of the filter plate (4) and the filter holes (6) set on the arc bottom plate of the grid hopper is 5 to 10 cm. The distance between the filter plate (4) and the bottom of the loading box is not less than 10 cm. The number of times the excavator shakes its arm is not less than 3.

8. The construction method for controlling the content of fine-particle rockfill in rockfill dams according to claim 7, characterized in that: When filling the rockfill in each rockfill area, a mixed paving method of advancing and retreating is adopted. After paving, the rockfill is leveled by bulldozers and / or excavators, and then compacted and filled according to the specified compaction parameters. Finally, bulldozers are used to remove the broken fine powder layer on the surface and roughen the surface.

9. The construction method for controlling the content of fine-particle rockfill in rockfill dams according to claim 8, characterized in that: The compaction parameters include the number of compaction passes, the driving route of the compaction machinery, and the speed. When determining the compaction driving route, compaction should be carried out along a straight route, and the compaction range between two adjacent compaction lines should overlap by at least 10cm. When scraping off the surface broken fine powder layer, the scraping operation should be carried out 1-2 times by a bulldozer.

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