A wind farm wind turbine installation platform foundation precision backfill construction method

Abstract

The application discloses a kind of wind farm fan installation platform foundation precision backfill construction method, it is related to wind power foundation construction technical field, the specific steps of this method are as follows: first, according to drawing line division operation zone and set up storage area;Again, from top to bottom layer excavation screening soil material, side slope synchronous step compaction;From inside to outside partition backfill, set different virtual paving thickness and compaction detection;Each layer covers the outside of step, two-stage step joint place paving gravel reinforcement;Each layer is measured settlement and dynamically adjusts filler parameter;Finally, fine material leveling, surplus material is used for covering soil, vegetation and drainage;The application adopts radial zoning operation and soil grading screening integrated mode, differentiates and matches the stress demand of each area, cooperates with step gravel reinforcement and standard interlayer treatment, improves backfill compaction uniformity, dynamically regulates and controls filler parameter by layer settlement monitoring, actively controls uneven settlement;Surplus material is used for covering soil, vegetation and drainage, realizes quality closed-loop control and green construction.

Description

Technical Field

[0001] This invention relates to the field of wind power foundation construction technology, specifically a method for precise backfilling construction of wind turbine installation platform foundations in wind farms. Background Technology

[0002] Wind power, as a clean and renewable energy source, plays a crucial role in the global energy structure transformation. Wind turbines are typically located in areas rich in wind resources, such as mountains, hills, plateaus, tidal flats, and reclaimed mining areas. These areas have complex and diverse geological conditions, including hard rock foundations, soft soil layers, backfilled areas, and karst development zones. The foundation treatment quality of the wind turbine installation platform, serving as the temporary load-bearing structure for wind turbine hoisting operations and the operating site for foundation construction, directly affects the smooth progress of subsequent wind turbine foundation construction. After the wind turbine foundation construction is completed, large-scale backfilling of the foundation pit is required. The backfill soil not only protects the foundation and transmits the superstructure load, but also directly affects the vertical displacement and tilt state of the wind turbine tower during its operating cycle. As the capacity of individual wind turbines continues to increase and the tower height continues to rise, the load on the wind turbine foundation is becoming increasingly greater, and the quality requirements for foundation backfilling construction are also increasing. Therefore, how to achieve high-quality construction of wind turbine installation platform foundation backfilling under complex geological conditions is a technical direction that requires continuous attention in wind power engineering construction.

[0003] Traditional wind turbine foundation backfilling construction does not systematically screen and classify the excavated soil. Various coarse and fine particles, debris, and large pieces of soft rock are simultaneously filled into the foundation pit. The gradation of the fill material is uncontrolled. Excessive fine material in some areas can lead to excessive compression deformation, while areas with concentrated coarse material can easily form voids. Overall compaction uniformity is difficult to guarantee. In the construction process, independent working zones are not divided according to the radial stress characteristics of the annular foundation pit. The same type of fill material, the same paving thickness, and the same compaction equipment are used uniformly. The soil strength in the inner ring bearing area is insufficient, and the surface soil of the outer ring has poor erosion and deformation resistance. The construction capacity is relatively weak. The interface between the steps formed by the excavation of the foundation pit slope is simply paved with soil without any special reinforcement structure. The interface between the new and old soil is prone to shear slippage. The layered construction lacks a settlement monitoring system throughout the process, making it impossible to monitor the compression deformation of each layer of soil in real time. There are no standardized adjustment methods after settlement deviation occurs, which easily leads to uneven settlement after completion. There is no overall utilization plan for the excess soil generated from the excavation. The large amount of soil transported off-site increases the construction cost. The elevation control relies on rough manual adjustment, and the flatness of the top surface is difficult to meet the design accuracy requirements. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a precise backfilling construction method for the foundation of wind turbine installation platforms in wind farms. This method establishes a standardized and refined construction system around the entire process of backfilling the annular foundation pit of the wind turbine. First, the working area of ​​the foundation pit and the material storage area are planned in zones based on drawings and geological data. During excavation, the soil is screened and impurities are removed, and the soil is stacked according to particle size. During construction, backfilling is carried out in radial zones with different gradations. The corresponding graded fill material is selected to match the stress of each area. The layered operation is completed with appropriate compaction equipment. Crushed stone reinforcement structures are added to the interface of the steps to improve the bonding strength. Settlement observation points are set up during the construction process. The subsequent fill material, paving and compaction parameters are dynamically adjusted based on the measured settlement data of each layer to accurately control the overall settlement deformation. Fine-grained material is used for leveling in the final stage of backfilling, and various residual granular materials are utilized in multiple scenarios.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm, the specific steps of which are as follows:

[0006] S1. Based on the design drawings and geological survey data, the excavation and filling boundaries are demarcated, the layer thickness and step height are determined, the annular backfill area is divided into multiple continuous working zones along the radial direction, and an isolated granular material storage area is set up around the foundation pit.

[0007] S2, excavate in layers from top to bottom, with the depth of each layer matching the thickness of the layer. Use mobile screening equipment to screen the soil into coarse, medium and fine particles, remove impurities and stockpile in sections; when excavating to the interface, excavate horizontal steps on the slope and compact them simultaneously.

[0008] S3, spread the filler of the corresponding particle size in each working zone in the order from the inside to the outside, set the differentiated loose thickness, compact it with matching compaction equipment, and test the compaction degree after interlayer treatment;

[0009] The differentiated loose paving thickness is as follows: inner working strip 230mm~270mm, middle inner working strip 280mm~320mm, middle outer working strip 330mm~370mm, outer working strip 260mm~300mm;

[0010] S4, each layer of filler extends to cover the outside of the step and is compacted parallel to the step direction; a crushed stone reinforcement layer is laid at the vertical intersection of every two steps, and the interface compaction degree and shear strength are tested after compaction;

[0011] S5. After the first layer is compacted, measuring points are set up to measure the settlement and determine the benchmark settlement rate for each area. The settlement rate of each subsequent layer is measured, and the gradation of the fill material, the loose layer thickness and the number of compaction passes are adjusted according to the deviation. The total settlement is then calculated.

[0012] S6. When the backfill is close to the design elevation, use a thin layer of fine-grained material to level it and control the elevation and flatness; the remaining granular material is used for surface soil covering, slope vegetation paving and drainage cushion layer respectively.

[0013] Furthermore, in S1, φ16mm to φ20mm steel control piles are installed every 4m to 6m along the dividing line, with an insertion depth ≥30cm; the layer thickness and step height are both 280mm to 320mm; the annular space is radially divided into 3 to 4 working zones, with a width of 1.2m to 1.8m; the area of ​​a single granular material storage area is ≥20m². 2 The sections are separated by earthen embankments, and temporary drainage ditches and impermeable geomembranes with a thickness of 0.5mm to 1.0mm are also provided.

[0014] Furthermore, in S2, a bucket capacity of 0.8m³ is used. 3 ~1.2m 3 Excavation is carried out using a backhoe, leaving a 15cm-25cm layer for manual trimming, with each layer having a depth of 280mm-320mm; screening is performed using a process capacity of 80-120m³. 3 A vibrating screen with a capacity of / h has upper screen apertures of 18mm to 22mm, lower screen apertures of 4mm to 6mm, an inclination angle of 15° to 20°, a frequency of 16Hz to 20Hz, and a particle quality rate of ≥95%. Coarse particles are those with a diameter >20mm, medium particles are those with a diameter of 5 to 20mm, and fine particles are those with a diameter <5mm.

[0015] Furthermore, in S2, tree roots, garbage, and weak rock blocks with a particle size >100mm are removed during screening; the mud content of coarse material is ≤5% and the organic matter content of fine material is ≤5%; the height of the horizontal step is 280mm~320mm, the width is 450mm~600mm, the inward inclination of the step surface is 2%~3%, and the base surface is compacted 3~5 times using an impact rammer with an impact energy ≥15kN·m.

[0016] Furthermore, in S3, the proportion of coarse aggregate in the inner working zone is ≥70%, the proportion of coarse aggregate in the inner and outer working zones is ≥75%, and the proportion of fine aggregate in the outer working zone is ≥80%; the coarse aggregate has a non-uniformity coefficient Cu≥5, a curvature coefficient Cc of 1~3, a maximum particle size ≤2 / 3 of the loose layer thickness and ≤60mm, and a plasticity index Ip ≤12.

[0017] Furthermore, in S3, the inner strip is compacted 5-7 times with an electric rammer with a base diameter of 200mm-240mm, with the compaction points overlapping in a staggered pattern by 1 / 3 of the area; the middle inner strip is compacted 3-5 times with a 1t vibratory roller with an excitation force ≥10kN at a speed ≤2km / h; the middle outer strip is compacted 2-4 times with a 3t vibratory roller with an excitation force ≥30kN at a speed ≤3km / h; and the outer strip uses a 0.25m... 2 The plate compactor should be used 3 to 5 times; the compaction paths should overlap by 1 / 3 of the wheel width.

[0018] Furthermore, in S3, the circumferential spacing between the upper and lower layer joints is ≥1m, and they avoid the corners of the foundation; before paving, the moisture content is adjusted to within ±2% of the optimum moisture content, the roughening depth is 10-15mm, and the roughening spacing is 90mm-110mm; the compaction degree is tested using the sand cone method, every 80m 2 ~120m 2 At least one point should be measured, and the absolute value of the deviation between the measured compaction degree of each area and the design standard value should be ≤2%.

[0019] Furthermore, in S4, the filler material covers the outer edge of the step with a length ≥ 1 / 2 of the step width and ≥ 250 mm; the compaction trajectory is parallel to the step and ≥ 200 mm from the edge of the original soil; the crushed stone reinforcement layer uses granite crushed stone with a particle size of 20-40 mm, a crushing value ≤ 26%, an abrasion value ≤ 20%, a mud content ≤ 3%, a thickness of 80 mm-120 mm, and extends ≥ 500 mm into each excavation and filling area; the bottom is cleaned and pre-compacted before laying.

[0020] Furthermore, in S5, settlement measuring points are pre-embedded with φ16mm steel bars, arranged radially in a 4m×4m~6m×6m grid; a DSZ2 level is used to measure with second-order accuracy, and the absolute value of the mean square error of the forward and backward elevation difference is ≤1.0mm / km; after the first layer is compacted, the benchmark settlement rate is determined as follows: 8%~10% for coarse-grained material area, 10%~12% for medium-grained material area, and 12%~15% for fine-grained material area, and the average value of 3 measured points in the same area is taken as the benchmark.

[0021] Furthermore, in S5, if the measured settlement rate is 5% to 10% higher than the benchmark value, the proportion of coarse aggregate in the lower layer of that area increases by 3% to 7%, the loose-lay thickness decreases by 15mm to 25mm, and the number of compaction passes increases by 1; if the measured settlement rate is >10% higher than the benchmark value, the proportion of coarse aggregate increases by 8% to 12%, the loose-lay thickness decreases by 15mm to 25mm, and the number of compaction passes increases by 2; if the measured settlement rate is >5% lower than the benchmark value, the proportion of fine aggregate increases by 3% to 7%, the loose-lay thickness increases by 15mm to 25mm, and the number of compaction passes decreases by 1; the total settlement corresponding to 80% to 90% consolidation degree is calculated using the layer summation method. If the calculated value exceeds the limit, the number of compaction passes for each subsequent layer increases by 1.

[0022] Compared with existing technologies, this method for precise backfilling of wind turbine installation platform foundations in wind farms has the following advantages:

[0023] I. This invention achieves refined control over backfill materials and work space through an integrated construction mode combining radial zoning operations in a ring-shaped backfill area with graded screening and storage of soil materials. First, independent work zones are divided according to site geology and design requirements, with dedicated storage areas. During the excavation phase, soil grading and impurity removal are completed simultaneously, separating soils of different particle sizes for separate storage. This avoids the problem of insufficient overall backfill stability caused by mixed fillers and impurities from the source. Differentiated filler ratios match the backfill requirements of different radial positions. Suitable graded soils are selected for the inner, middle, and outer areas, balancing internal load-bearing capacity and external surface protection needs. Combined with a stepped interface crushed stone reinforcement structure, the bonding performance at the junction of new and old soil is strengthened, weakening the weak defects at layering and step joints. Layered spreading and compaction are accompanied by standardized interlayer treatment methods, controlling soil moisture content and joint staggering distances, and unifying compaction testing standards. This significantly improves the overall density and uniformity of the backfill, reduces the probability of local voids and insufficient compaction, continuously optimizes the overall load-bearing performance of the wind turbine foundation ring-shaped backfill structure, and enhances the structural integrity during long-term use.

[0024] II. This invention achieves dynamic control of backfill construction quality and efficient utilization of materials through a layered settlement dynamic monitoring and control mechanism combined with a waste material disposal process. After each layer of backfill is completed, settlement observation points are set up throughout the area to accurately collect layered settlement data and establish zonal settlement benchmark standards. Based on real-time settlement data, the gradation of the lower layer fill material, the paving thickness, and the frequency of compaction operations are adjusted in reverse to correct soil compression deformation deviations in a timely manner, actively control the overall total settlement and settlement difference, and avoid foundation displacement and cracking caused by uneven settlement in the later stage. When backfilling to the design elevation, a fine-grained material thin-layer leveling process is used to accurately control the flatness of the top surface. Various types of residual granular materials produced by screening are used for surface cover, slope ecological paving, and drainage structures, respectively, to achieve full utilization of excavated and screened materials, reduce earthwork transportation and external purchase of fill material. The entire construction process forms a closed-loop control system, reduces manual rework and repair procedures, shortens the on-site construction cycle, and reduces earthwork waste and construction waste emissions, taking into account the requirements of engineering construction quality control and green construction of the site.

[0025] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0027] Figure 1 A flowchart illustrating the overall process of precise backfilling construction for wind turbine foundations in a wind farm.

[0028] Figure 2 This is a schematic diagram of the radially segmented differentiated paving and compaction process;

[0029] Figure 3 Schematic diagram of the construction of the crushed stone reinforcement interface for slope steps;

[0030] Figure 4 This is a flowchart for stratified settlement monitoring and dynamic parameter control. Detailed Implementation

[0031] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0032] Example 1:

[0033] A method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm.

[0034] Based on the wind turbine foundation design drawings and site geotechnical investigation data, on-site measurement and layout were carried out to mark the inner and outer contours of the foundation pit and the boundary line between excavation and filling. A φ18mm steel control pile was laid every 5m along the excavation-filling boundary line, with the steel bars inserted into the soil to a depth of 35cm. The piles were fixed and stable without any deviation.

[0035] The annular backfill area is evenly divided into four continuous working zones along the radial direction. The radial width of each working zone is 1.5m, and the layer filling thickness and slope step height are both set at 300mm.

[0036] A separate, independent aggregate storage area was designated outside the foundation pit, with four storage zones, each with an actual usable area of ​​22m². 2 The zones are separated and protected by 30cm high plain soil embankments. A 0.8mm thick impermeable geomembrane is laid at the bottom of each stockpile area. Temporary drainage ditches with a cross section of 30cm wide and 20cm deep are excavated around the stockpile area to collect rainwater and drain it to an off-site sump to prevent the soil from softening due to water immersion.

[0037] Select a bucket capacity of 1.0m³. 3 The backhoe excavator excavates layer by layer from top to bottom, with the depth of each excavation controlled between 290mm and 320mm. After each layer is excavated, a 20cm thick layer of soil is left for manual trimming to ensure that the sidewalls of the pit are flat and straight.

[0038] When excavating to the interface between the foundation pit and the original soil, horizontal steps are excavated on the slope simultaneously. The step height is 300mm and the step width is 500mm. The step faces the inside of the foundation pit with an inward slope of 2.5%. After each step is excavated, the step base surface is compacted 4 times using an impact rammer with an impact energy of 16kN·m.

[0039] Configuration processing capacity 100m 3 A mobile vibrating screen with a capacity of / h is used for soil screening. The upper screen has a mesh size of 20mm, the lower screen has a mesh size of 5mm, the screen body is installed at an inclination angle of 18°, and the vibration frequency is 18Hz. All excavated soil is fed into the screening equipment for grading and automatically separated into three types of fillers: particles larger than 20mm are coarse particles, particles between 5mm and 20mm are medium particles, and particles smaller than 5mm are fine particles. The overall qualified rate of the granular material after screening is 96.2%.

[0040] During the screening process, tree roots, plastic waste, and weak rock fragments with a particle size exceeding 100mm are manually removed from the soil. The coarse aggregate has a mud content of 4.2%, and the fine aggregate has an organic matter content of 3.8%. The three types of aggregates are stacked in separate areas, with the stack height controlled at 1.8m to prevent landslides and mixing caused by excessively high stacks.

[0041] Following the construction sequence of filling from the inside of the pit to the outside, the four radial working zones each use fillers with corresponding gradations. The inner working zone filler has a granular material content of 72%, the middle inner and middle outer working zones have a coarse material content of 78%, and the outer working zone has a fine material content of 83%.

[0042] The coarse-grained material has a non-uniformity coefficient of 6.2, a curvature coefficient of 2.1, a maximum particle size of 50 mm, and a plasticity index of 9 for the fine-grained material.

[0043] The thickness of the paving is controlled differently for the four working zones: 250mm for the inner zone, 300mm for the middle inner zone, 350mm for the middle outer zone, and 280mm for the outer zone. On-site, steel wire lines and rulers are used in conjunction with bulldozer paving operations, and manual trimming is performed on the uneven parts of the edges and corners.

[0044] Each work zone is compacted in layers using appropriate compaction equipment. The inner work zone uses an electric impact rammer with a base diameter of 220mm, compacted 6 times, with the compaction points arranged in a quincunx pattern, and adjacent compaction points overlapping by 1 / 3 of the compacted area. The middle inner work zone uses a vibratory roller with a self-weight of 1t and a vibration force of 12kN, compacted 4 times, with the travel speed controlled at 1.8km / h. The middle outer work zone uses a vibratory roller with a self-weight of 3t and a vibration force of 35kN, compacted 3 times, with the travel speed controlled at 2.6km / h. The outer work zone uses a 0.25m... 2 A small plate compactor is used, and compaction is performed four times. The lateral overlap width of all rolling and compaction tracks is 1 / 3 of the wheel width or the width of the compaction base. Specific steps are as follows: Figure 2 As shown.

[0045] The circumferential joints of the upper and lower fill layers are staggered by 1.2m, completely avoiding the stress concentration areas at the four corners of the foundation. Before the fill material is laid, the soil moisture content is tested and adjusted to within 2% of the optimum moisture content by watering or drying. Before filling the lower layer, the top surface of the upper layer is thoroughly roughened to a depth of 12mm and the roughening points are spaced 100mm apart.

[0046] After each layer is compacted, the compaction degree is tested using the sand cone method, every 100m. 2 One testing point is set up, and the difference between the measured compaction degree of each area and the design standard value is controlled within 1.5%.

[0047] Each layer of fill material extends outwards to cover the outer edge of the step, with an extension length of 300mm. The compaction route is parallel to the direction of the step, and the compacted edge is 220mm away from the original soil slope to avoid disturbing the original foundation.

[0048] At the junction of every two vertical steps, a crushed stone reinforcement layer is laid. This layer uses 20mm to 40mm granite crushed stone with a crushing value of 23%, an abrasion value of 17%, and a mud content of 2.1%. The reinforcement layer is 100mm thick and extends 550mm into both the backfill area and the outer undisturbed soil area. Before laying the crushed stone, loose soil and debris at the step junctions are manually removed. A small plate compactor is used to pre-compact the base. After the crushed stone is laid, the entire surface is compacted. The compaction degree and soil shear strength at the interface locations are tested layer by layer. After testing, the upper layer filling operation is carried out, with specific steps as follows: Figure 3 As shown.

[0049] After the first layer of fill material was compacted, settlement observation points were set up. φ16mm steel bar ends were pre-embedded as observation markers, and the points were evenly distributed according to a 5m×5m grid combined with a radial radiation method. Settlement data were collected using a high-precision level instrument with second-order leveling standards. The mean square error of the forward and backward elevation difference was 0.8mm / km.

[0050] The benchmark settlement rate was determined by on-site zoning measurements. The benchmark settlement rate was 9% for the coarse aggregate filling area, 11% for the medium aggregate area, and 13% for the fine aggregate area. The arithmetic mean of three measuring points in each zone was taken as the standard benchmark value.

[0051] After each layer of fill is compacted, settlement measurements are conducted, and the construction parameters of the next layer are dynamically adjusted based on the benchmark settlement rate. If the measured settlement rate exceeds the benchmark value by 7%, the proportion of coarse aggregate in the next layer of fill material in that area is increased by 5%, the loose-lay thickness is reduced by 20mm, and the number of compaction passes is increased by one. If the measured settlement rate exceeds the benchmark value by 12%, the proportion of coarse aggregate is increased by 10%, the loose-lay thickness is reduced by 20mm, and the number of compaction passes is increased by two. If the measured settlement rate is lower than the benchmark value by 6%, the proportion of fine aggregate is increased by 5%, the loose-lay thickness is increased by 20mm, and the number of compaction passes is reduced by one.

[0052] The total settlement corresponding to 85% consolidation of the soil is calculated using the layered summation method. If the calculated total settlement exceeds the design allowable limit, the number of compaction passes for each subsequent layer is increased by one to continuously control settlement deformation. The specific steps are as follows: Figure 4 As shown.

[0053] When the backfilling construction reaches 30cm from the design elevation, replace it with fine aggregate for thin-layer paving and leveling. The thickness of each paving is 80mm. The layers are finely leveled. The level instrument tracks and controls the top surface elevation and overall flatness in real time. The elevation error is controlled within ±10mm, and the flatness deviation is no more than 15mm.

[0054] After backfilling, the remaining screened aggregates were sorted, transported, and utilized. Fine aggregates were used entirely for the foundation surface covering, medium aggregates were laid on the slope surface as a vegetation cushion layer, and coarse aggregates were uniformly laid in the ring-shaped drainage cushion layer around the foundation pit. This ensured complete utilization of the screened soil, with no excess soil transported away. Specific steps are as follows: Figure 1 As shown.

[0055] Example 2:

[0056] Filler grading and interface reinforcement effect verification.

[0057] Verification of soil grading effect:

[0058] On-site configuration processing capacity: 80m 3 / h and 120m 3 A comparative test was conducted on two vibrating screening devices with a screen body inclination angle of 18°, a vibration frequency of 18Hz, and upper and lower screen apertures of 20mm and 5mm, respectively.

[0059] Equal amounts of undisturbed soil from the foundation pit were fed into two screening machines and continuously screened for 2 hours. Three types of granular materials were collected, weighed, and statistically analyzed. The processing capacity is 80m³. 3 The screening equipment has a particle size distribution rate of 95.1% per hour and a processing capacity of 120m³. 3 The overall qualified rate of granules in the screening equipment is 96.5% per hour. The grading uniformity of the large-capacity screening equipment is higher. Large-capacity vibrating screening equipment is preferred for large-scale backfilling construction.

[0060] After screening, the core control indicators of the three types of fillers were tested. The mud content of coarse material ranged from 3.2% to 4.8%, and the organic matter content of fine material ranged from 2.7% to 4.5%. After manual sorting, there were no large soft rocks, plant roots, or domestic waste inside the soil, and the purity of the filler was stable.

[0061] Three sets of comparative stockpiles were set up with stockpiling heights of 1.5m, 2m, and 2.5m. In the area with a stockpile height of 2.5m, the bottom stockpile was crushed and mixed with coarse and fine particles. In the areas with a stockpile height of 2m and below, the stockpile was clearly graded and there was no mixing of materials. The maximum height for stratified stockpiling of stockpile on site was set at 2m.

[0062] Verification of the compaction effect of the stepped base surface:

[0063] The height of the construction steps is uniformly 300mm, and the step widths are set in three groups of 450mm, 500mm, and 600mm respectively. The inward slope of the steps is set at 2%, 2.5%, and 3% respectively. The compaction of the base surface is compared with that of impact tampers with different tamping energies.

[0064] After three passes of compaction with an impact tamper with an impact energy of 12 kN·m, the compaction degree of the step base surface only reached 91%. After three passes with an impact tamper with an impact energy of 15 kN·m, the compaction degree reached 95%, and after four passes with an impact tamper with an impact energy of 15 kN·m, the compaction degree reached 97%. When the step width was 450 mm, water accumulation on the inner side was severe. Steps with a width of 500 mm and 600 mm had smooth drainage, and an inward slope of 2.5% had the best drainage effect.

[0065] Based on comprehensive comparison, the construction parameters for the steps were determined: step height 300mm, width 500mm, inward slope 2.5%, and an impact rammer with an impact energy of not less than 15kN·m was selected. The base surface was compacted no less than 3 times.

[0066] Verification of interface reinforcement effect:

[0067] Two sets of step interface samples were set up: one without a crushed stone reinforcement layer and the other with a 100mm thick crushed stone reinforcement layer. Direct shear tests were conducted to detect the shear strength.

[0068] Without a crushed stone reinforcement layer, the interface shear strength is low, making it prone to step slippage and cracking under load. After laying the granite crushed stone reinforcement layer, the interface shear strength increases by 32%, and the integrity of the vertical step junction is greatly improved, effectively resisting shear deformation caused by long-term loads on the wind turbine foundation.

[0069] Cleaning and pre-compacting the base before laying crushed stone can further improve the bonding between the reinforcement layer and the soil above and below, and avoid the phenomenon of voids between layers.

[0070] Example 3:

[0071] Optimization of key parameters for backfilling construction.

[0072] Optimization of loose-lay thickness in the work zone:

[0073] Simultaneously, single-factor optimization tests were conducted on the loose paving thickness of four radial working zones. The inner working zone had three loose paving thicknesses of 200mm, 250mm, and 300mm, compacted six times with an electric rammer. The middle inner zone had three loose paving thicknesses of 250mm, 300mm, and 350mm, compacted four times with a 1t vibratory roller. The middle outer zone had three loose paving thicknesses of 300mm, 350mm, and 400mm, compacted three times with a 3t vibratory roller. The outermost zone had three loose paving thicknesses of 230mm, 280mm, and 330mm, compacted four times with a plate compactor.

[0074] After each group of fillings was completed, the compaction degree and layer settlement were tested. The optimal compaction efficiency and uniform settlement deformation were achieved when the loose paving thickness was 250mm on the inner side, 300mm in the middle inner side, 350mm in the middle outer side, and 280mm on the outer side. Excessive thickness can easily lead to insufficient compaction of the lower layer, while insufficient thickness will significantly reduce construction efficiency.

[0075] Optimization of filler moisture content and interlayer roughening parameters:

[0076] Medium-sized aggregates were selected for moisture content optimization tests. The soil moisture content was controlled to be 4% below the optimum value, 2% below the optimum value, optimum moisture content, 2% above the optimum value, and 4% above the optimum value, respectively. The interlayer bond strength was tested after paving and compaction.

[0077] When the moisture content deviates from the optimal value by 2%, there is no delamination or slippage between layers. When the moisture content deviation exceeds 2%, the interlayer shear strength decreases significantly, and delamination cracking is likely to occur.

[0078] The shaving depths were set to 8mm, 10mm, 15mm, and 20mm, and the shaving spacings were set to 80mm, 100mm, and 120mm for comparison. When the shaving depth was 10 to 15mm and the spacing was 100mm, the interlocking effect between the upper and lower layers was the best, and the overall integrity between the layers was strong.

[0079] Parameter optimization of crushed stone reinforcement layer:

[0080] The crushed stone reinforcement layer at the step junction was set with three thicknesses of 80mm, 100mm and 120mm, the crushed stone extension length was set with three groups of 300mm, 500mm and 700mm, and the crushed stone particle size was set with three groups of 10 to 30mm, 20 to 40mm and 30 to 50mm for comparison.

[0081] An 80mm thick reinforcing layer has insufficient interfacial shear strength, while a 120mm thick crushed stone layer consumes a lot of material and is not economical. A 100mm thick layer has the best overall performance. When the crushed stone extends less than 500mm into the cut-fill area, stress concentration is likely to occur at the step junction. Granite crushed stone with a thickness of 20 to 40mm exhibits the best crushing value and abrasion index.

[0082] Table 1 shows a comparison of compaction effects under different loose-lay thicknesses:

[0083] Work zone location Loose layer thickness Number of compaction passes compaction Stratified settlement Inner working zone 200mm 6 96.8% 7.2mm Inner working zone 250mm 6 96.3% 8.5mm Inner working zone 300mm 6 94.7% 10.1mm Inner working belt 250mm 4 95.2% 9.3mm Inner working belt 300mm 4 96.1% 10.8mm Inner working belt 350mm 4 94.4% 12.6mm Sino-foreign work belt 300mm 3 95.7% 8.8mm Sino-foreign work belt 350mm 3 96.5% 10.2mm Sino-foreign work belt 400mm 3 93.9% 12.9mm outer working zone 230mm 4 96.2% 11.7mm outer working zone 280mm 4 95.8% 13.2mm outer working zone 330mm 4 94.1% 15.6mm

[0084] The comparison results in Table 1 show that each working zone has an optimal loose-lay thickness range, within which the compaction degree is at a high level, and the stratified settlement is uniform and stable. When the loose-lay thickness is too small, the amount of compaction work required per unit volume of fill material increases, and the construction efficiency decreases. When the loose-lay thickness is too large, the compaction energy cannot be effectively transferred to the bottom of the layer, resulting in insufficient bottom compaction, significantly increased stratified settlement, and a tendency to cause uneven settlement problems later on. The selected four sets of standard loose-lay thicknesses can balance construction efficiency and settlement uniformity while ensuring compaction quality.

[0085] Example 4:

[0086] Settlement dynamic control effect test.

[0087] Benchmark settlement rate calibration:

[0088] Three types of filling areas were selected: coarse-grained material, medium-grained material, and fine-grained material. Five measuring points were set up in each area. After the first layer was compacted, the settlement data was continuously observed for 72 hours. The settlement rate of each measuring point was calculated. After removing abnormal values, the average value of three stable measuring points was taken as the baseline settlement rate of the area.

[0089] The measured settlement rate ranged from 8% to 10% in the coarse aggregate area, 10% to 12% in the medium aggregate area, and 12% to 15% in the fine aggregate area. The settlement differences among the three types of zones were significant, and the benchmark values ​​for each zone needed to be determined separately for layered construction.

[0090] Settlement deviation control effect:

[0091] For different degrees of settlement rate deviation, corresponding parameter adjustment schemes were used to carry out comparative tests, and the measured settlement rate of the lower layer after adjustment was recorded to verify the effectiveness of the control scheme.

[0092] When the settlement rate is 5% to 10% higher than normal, increasing the proportion of coarse aggregate, reducing the loose layer thickness, and increasing the number of compaction passes can effectively reduce the settlement rate. When the settlement rate is more than 10% higher than normal, increasing the gradation adjustment range and increasing the number of compaction passes will result in more significant settlement control. When the settlement rate is more than 5% lower than normal, increasing the proportion of fine aggregate, increasing the loose layer thickness, and reducing the number of compaction passes can bring the settlement rate back to a reasonable range.

[0093] Overall settlement control effect:

[0094] Two wind turbine foundations were selected for synchronous construction comparison. One site did not adopt layered settlement dynamic control, while the other site strictly adjusted the filler gradation, loose-lay thickness, and number of compaction passes according to settlement monitoring data.

[0095] Without settlement control measures, the measured total settlement after foundation completion exceeded the design limit by 18 mm, with a local uneven settlement difference of 12 mm. With the dynamic settlement control scheme, the total settlement corresponding to 85% consolidation was entirely within the design limit, and the uneven settlement difference between adjacent areas was less than 4 mm.

[0096] Table 2 compares the control effects under different settlement deviation conditions:

[0097] Packing partition Settlement deviation Pre-regulation subsidence rate Adjustment of coarse material ratio Loose layer thickness adjustment Adjustment of compaction passes Settlement rate after regulation Coarse material zone 7% higher 9.6% +5% -20mm +1 time 9.1% Coarse material zone 12% higher 10.3% +10% -20mm +2 times 9.2% medium-sized feed zone 8% higher 11.9% +5% -20mm +1 time 11.2% medium-sized feed zone 13% higher 12.7% +10% -20mm +2 times 11.4% Fine-grained area 6% higher 14.2% +5% -20mm +1 time 13.5% Fine-grained area 11% higher 15.1% +10% -20mm +2 times 13.8% Fine-grained area 7% lower 11.3% -5% +20mm -1 time 12.6%

[0098] According to the comparative data in Table 2, the tiered control scheme can accurately correct settlement deviations of different degrees. When the settlement rate is high, increasing the proportion of coarse aggregate, reducing the thickness of the ply, and increasing the number of compaction passes can effectively improve soil density and reduce subsequent settlement. When the settlement rate is low, adjusting the parameters in the opposite direction can avoid uneven stiffness caused by excessive soil compaction. The settlement rate after adjustment under all working conditions returns to near the benchmark range. The control scheme is highly targeted and can effectively control the uniformity of tiered settlement, reducing the overall total settlement and the risk of uneven settlement.

[0099] Example 5:

[0100] Zoned compaction quality and interlayer bonding performance testing.

[0101] Compaction degree testing for each work zone:

[0102] After each layer of backfill is completed, it should be done at a rate of 100m. 2 One testing point was set up using the sand-filling method, and the actual compaction data were collected in four work zones.

[0103] The measured compaction degree of the inner medium-grained material zone ranged from 95.2% to 97.1%, the inner and outer coarse-grained material zones ranged from 95.8% to 97.5%, and the outer fine-grained material zone ranged from 94.9% to 96.6%. The difference between the measured values ​​and the design standard values ​​at all points was less than 2%, and there were no local under-compacted areas.

[0104] Interlayer bond strength test:

[0105] Shear tests were conducted on interlayer bonding specimens with different planing parameters. Specimens with a planing depth of 10 to 15 mm and a planing spacing of 100 mm showed a 28% increase in interlayer shear strength compared to unplaned specimens. The interlayer bonding effect was optimal when the moisture content of the upper and lower layers of filler was controlled near the optimum moisture content; excessive deviation in moisture content could easily lead to weak interlayers.

[0106] Comparison of staggered circumferential seams:

[0107] Two sets of joint construction sections were set up, one with the upper and lower layer joints staggered by a distance of 0.8m, and the other with a distance staggered by a distance of 1.2m. The compaction degree and shear strength at the joint locations were tested.

[0108] In test sections where joints were staggered by less than 1 meter, the compaction degree at the joints was 3% to 4% lower than that of the overall area, and the shear strength also decreased significantly. In construction sections where joints were staggered by more than 1 meter, the compaction degree at the joints was not significantly different from that of the overall area, and the interlayer integrity was good.

[0109] Table 3 compares the compaction quality test results for different work zones:

[0110] Work zone location Packing dominant type Number of detection points Average compaction Maximum compaction Minimum compaction Maximum deviation of a single point from the standard value Inner working zone medium-sized grains 12 96.2% 97.1% 95.2% 1.2% Inner working belt coarse grains 15 96.7% 97.5% 95.8% 1.0% Sino-foreign work belt coarse grains 15 96.6% 97.3% 95.9% 0.9% outer working zone Fine granules 12 95.7% 96.6% 94.9% 1.8%

[0111] According to the test results in Table 3, the average compaction degree of the four working zones is at a high level. Among them, the inner and outer working zones dominated by coarse-grained materials have the best compaction effect, followed by the inner working zone of medium-grained materials, while the average compaction degree of the outer working zone of fine-grained materials is slightly lower but still remains stable. The compaction degree deviation of all test points is within a small range, with no obvious weak points. This indicates that the scheme of selecting compaction equipment and different construction parameters for different zones is well adapted, which can achieve uniform compaction throughout the entire area and avoid local under-compaction or over-compaction problems.

[0112] Example 6:

[0113] Performance verification of the entire process.

[0114] Storage protection system suitability verification:

[0115] A dedicated granular material storage area with an impermeable geomembrane, isolation embankments, and temporary drainage ditches was set up around the foundation pit. After seven consecutive days of monitoring during rainfall, the geomembrane remained intact and undamaged, and the soil moisture content within the storage area remained stable, with no softening or soaking from rainwater. In contrast, the soil moisture content in the control storage area without impermeable and drainage measures increased significantly, requiring additional drying treatment before filling and delaying the construction schedule.

[0116] Single stockpile area less than 20m² 2 Under certain operating conditions, insufficient storage space for the three types of granular materials can easily lead to mixing. (Single zone area: 20m²) 2 The above methods can achieve complete separation and stacking of coarse and fine granules, resulting in stable screening and grading effects.

[0117] Stability of continuous construction throughout the entire process:

[0118] The project fully implemented six procedures: planning and zoning, excavation and screening, zonal backfilling, interface reinforcement, settlement control, and leveling and disposal. The foundation backfilling construction of three wind turbines was carried out continuously, and the construction efficiency, filler loss, and number of quality defects were recorded throughout the process.

[0119] No quality defects such as mixed fill material, layering voids, step slippage, or excessive settlement occurred during the construction of the three foundations, and the loss rate of screened soil was only 3.1%. In contrast, the traditional non-zoning and non-grading backfilling process resulted in a fill material loss rate of 11.7% and frequent uneven settlement defects.

[0120] Adaptability to different geological sites:

[0121] This construction method was applied to two typical wind farm sites: silty clay sites and gravel sites. For silty clay sites, the organic matter and mud content of fine-grained materials were strictly controlled, while for gravel sites, the gradation of coarse-grained materials was precisely adjusted. After the filling of both types of sites, the compaction degree and settlement index were stable.

[0122] Table 4 compares the comprehensive indicators under different construction scenarios:

[0123] Construction scene Single foundation construction period Soil loss rate Total settlement Uneven settlement difference Number of quality defects Application of this technology in silty clay sites 12 days 3.1% 22.6mm 3.2mm 0 Application of this technology in gravel and sandy sites 10 days 2.8% 18.4mm 2.7mm 0 Traditional techniques for silty clay sites 15 days 11.7% 38.2mm 12.1mm 4 places

[0124] As shown in the comprehensive comparative data in Table 4, this technology exhibits good adaptability to both types of geological sites. Compared with traditional backfilling methods, the construction period is significantly shortened, the soil loss rate is greatly reduced, and the total settlement and uneven settlement difference are both at lower levels. No quality defects occur during the construction process. The entire technology can be dynamically adjusted through parameters to adapt to different soil conditions, significantly improving both construction quality stability and engineering economy, and possesses broad engineering application value.

[0125] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm, characterized in that, The specific steps of this method are as follows: S1. Based on the design drawings and geological survey data, the excavation and filling boundaries are demarcated, the layer thickness and step height are determined, the annular backfill area is divided into multiple continuous working zones along the radial direction, and an isolated granular material storage area is set up around the foundation pit. S2, excavate in layers from top to bottom, with the depth of each layer matching the thickness of the layer. Use mobile screening equipment to screen the soil into coarse, medium and fine particles, remove impurities and stockpile in sections; when excavating to the interface, excavate horizontal steps on the slope and compact them simultaneously. S3, spread the filler of the corresponding particle size in each working zone in the order from the inside to the outside, set the differentiated loose thickness, compact it with matching compaction equipment, and test the compaction degree after interlayer treatment; The differentiated loose paving thickness is as follows: inner working strip 230mm~270mm, middle inner working strip 280mm~320mm, middle outer working strip 330mm~370mm, outer working strip 260mm~300mm; S4, each layer of filler extends to cover the outside of the step and is compacted parallel to the step direction; a crushed stone reinforcement layer is laid at the vertical intersection of every two steps, and the interface compaction degree and shear strength are tested after compaction; S5. After the first layer is compacted, measuring points are set up to measure the settlement and determine the benchmark settlement rate for each area. The settlement rate of each subsequent layer is measured, and the gradation of the fill material, the loose layer thickness and the number of compaction passes are adjusted according to the deviation. The total settlement is then calculated. S6. When the backfill is close to the design elevation, use a thin layer of fine-grained material to level it and control the elevation and flatness; the remaining granular material is used for surface soil covering, slope vegetation paving and drainage cushion layer respectively.

2. The method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm according to claim 1, characterized in that, In S1, φ16mm to φ20mm steel control piles are installed every 4m to 6m along the dividing line, with an insertion depth ≥30cm; the layer thickness and step height are both 280mm to 320mm; the annular space is radially divided into 3 to 4 working zones, with a width of 1.2m to 1.8m; the single area of ​​the granular material storage area is ≥20m². 2 The sections are separated by earthen embankments, and temporary drainage ditches and impermeable geomembranes with a thickness of 0.5mm to 1.0mm are also provided.

3. The method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm according to claim 1, characterized in that, In step S2, the screening process employs a capacity of 80–120 m³ / h. 3 A vibrating screen with a capacity of / h has upper screen apertures of 18mm to 22mm, lower screen apertures of 4mm to 6mm, an inclination angle of 15° to 20°, a frequency of 16Hz to 20Hz, and a particle quality rate of ≥95%. Coarse particles are those with a diameter >20mm, medium particles are those with a diameter of 5 to 20mm, and fine particles are those with a diameter <5mm.

4. The method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm according to claim 1, characterized in that, In step S2, tree roots, garbage, and weak rock blocks with a particle size >100mm are removed during screening. The mud content of coarse material is ≤5%, and the organic matter content of fine material is ≤5%. The height of the granular material layer is ≤2m. The height of the horizontal steps is 280mm~320mm, the width is 450mm~600mm, the inward inclination of the step surface is 2%~3%, and the base surface is compacted 3~5 times with an impact rammer with an impact energy ≥15kN·m.

5. The method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm according to claim 1, characterized in that, In S3, the proportion of granular material in the inner working zone is ≥70%, the proportion of coarse granular material in the inner and outer working zones is ≥75%, and the proportion of fine granular material in the outer working zone is ≥80%.

6. The method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm according to claim 1, characterized in that, In step S3, the inner strip is compacted 5-7 times with an electric rammer with a base diameter of 200mm-240mm, with the compaction points overlapping in a staggered pattern by 1 / 3 of the area; the middle inner strip is compacted 3-5 times with a 1t vibratory roller with an excitation force ≥10kN at a speed ≤2km / h; the middle outer strip is compacted 2-4 times with a 3t vibratory roller with an excitation force ≥30kN at a speed ≤3km / h; and the outer strip is compacted with a 0.25m... 2 The plate compactor should be used 3 to 5 times; the compaction paths should overlap by 1 / 3 of the wheel width.

7. The method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm according to claim 1, characterized in that, In S3, the circumferential distance between the upper and lower layer joints is ≥1m and avoids the corner of the foundation; before paving, the moisture content is adjusted to within the range of the optimum moisture content ±2%, and the roughening depth is 10~15mm and the roughening spacing is 90mm~110mm.

8. The method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm according to claim 1, characterized in that, In S4, the fill material covers the outer edge of the step with a length ≥ 1 / 2 of the step width and ≥ 250 mm; the compaction trajectory is parallel to the step and ≥ 200 mm from the edge of the original soil; the crushed stone reinforcement layer uses granite crushed stone with a particle size of 20-40 mm, a thickness of 80 mm-120 mm, and extends ≥ 500 mm into each excavation and filling area.

9. The method for precise backfilling of the foundation of a wind turbine installation platform in a wind farm according to claim 1, characterized in that, In S5, settlement measuring points are pre-embedded with φ16mm steel bar heads and arranged radially in a 4m×4m~6m×6m grid. After the first layer is compacted, the benchmark settlement rate is determined: 8%~10% for coarse-grained material area, 10%~12% for medium-grained material area, and 12%~15% for fine-grained material area. The average value of 3 measured points in the same area is taken as the benchmark.

10. The method for precise backfilling construction of wind turbine installation platform foundation in a wind farm according to claim 1, characterized in that, In step S5, if the measured settlement rate is 5% to 10% higher than the benchmark value, the proportion of coarse aggregate in the lower layer of that area increases by 3% to 7%, the loose-lay thickness decreases by 15mm to 25mm, and the number of compaction passes increases by 1; if the measured settlement rate is >10% higher than the benchmark value, the proportion of coarse aggregate increases by 8% to 12%, the loose-lay thickness decreases by 15mm to 25mm, and the number of compaction passes increases by 2; if the measured settlement rate is >5% lower than the benchmark value, the proportion of fine aggregate increases by 3% to 7%, the loose-lay thickness increases by 15mm to 25mm, and the number of compaction passes decreases by 1; the total settlement corresponding to 80% to 90% consolidation degree is calculated using the layer summation method. If the calculated value exceeds the limit, the number of compaction passes for each subsequent layer increases by 1.

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