Reverse excavation construction method for semi-filling and semi-excavating existing irrigation and water conservancy channel lining

Abstract

The invention relates to the technical field of irrigation and water conservancy engineering construction, and provides a half-filling and half-digging existing irrigation and water conservancy canal lining reverse excavation construction method which comprises the steps that section division and surface cleaning are conducted; full-section layered backfilling compaction is conducted; reverse excavation forming is conducted through a forming shovel; trimming and detecting a base surface; continuous lining is conducted, specifically, a bottom plate and side slope continuous follow-up mode is adopted for pouring, and it is ensured that pouring of the side slope is completed before bottom plate concrete is initially set; construction is conducted in all the construction sections through a warehouse-jumping method, and the adjacent warehouse blocks are poured in a warehouse-jumping mode. According to the method, multiple breakthroughs are realized in the transformation of the semi-filled and semi-excavated channel: the abandoned and purchased earthwork and the occupied area of a temporary storage yard are eliminated; reverse excavation is conducted after full-section layered compaction is conducted, a uniform high-density base plane is formed, and differential settlement is eradicated; the whole section of the shaping shovel is formed at a time, allowance is reserved, and geometric accuracy and slope straightness are guaranteed; the bottom plate and the side slope are continuously poured before initial setting, plastic combination is achieved, and construction cold joints are eliminated; and the exposure time of the base surface is strictly controlled, cement paste is brushed for remedy when time is out, and shrinkage stress is released by adopting a warehouse jumping method.

Description

Technical Field

[0001] This invention relates to the field of farmland water conservancy engineering construction technology, and in particular to a method for reverse excavation construction of existing farmland water conservancy channels with half-fill and half-cut lining. Background Technology

[0002] Existing farmland irrigation channels are mostly earthen canals or simply lined canals. After long-term operation, they generally suffer from problems such as siltation, leakage, and slope collapse, and urgently need to be upgraded with anti-seepage lining. Under semi-fill and semi-cut terrain conditions, existing channels often have irregular cross-sections, uneven settlement of the fill section, and slope instability of the cut section, posing unique technical challenges to traditional renovation construction.

[0003] Traditional channel lining construction techniques mainly include: 1. Traditional full-line open-cut excavation mode This is currently the most common method for renovating farmland irrigation canals. During construction, the entire canal axis is excavated to the designed cross-section, then the foundation is treated, and finally, lining is carried out. This method has the following inherent drawbacks: Earthwork balance is difficult: the excavation of the entire line generates a large amount of waste soil. Under the semi-fill and semi-excavation terrain, the excavated soil cannot be directly used for the fill section. It is necessary to transport the waste soil off-site or purchase fill soil from outside. The cost of earthwork transportation is high and the temporary storage yard occupies a large area. Long exposure time of the base surface: The long interval between excavation and lining causes the soil to dry and shrink due to the evaporation of moisture from the base surface, which affects the bonding quality between the concrete lining and the base layer and is prone to hollowing and cracking. Cross-section quality control is difficult: using excavators for rough slope cutting combined with manual trimming makes it difficult to guarantee the slope and flatness, resulting in uneven lining thickness and easy cracking and leakage in weak parts; Significant disturbance to arable land: Construction access roads and soil dumps occupy large amounts of farmland, conflicting with the basic farmland protection policy.

[0004] 2. Mechanized Lining Machine Construction Technology In large-scale water diversion projects, continuous construction using channel lining machines can achieve integrated excavation, slope sizing, and lining. However, this technology is suitable for newly constructed large channels and has the following limitations: Large and expensive equipment: The lining machine and its supporting equipment require huge investments and are not suitable for small and medium-sized farmland irrigation canals; Poor adaptability to terrain: It requires standardized channel cross-sections and good foundation conditions, and is difficult to adapt to the irregular cross-sections and weak foundations of existing channels that are partially filled and partially excavated. Excavation along the entire length is still required beforehand: earthwork excavation along the entire length still needs to be completed first, and the issues of earthwork balance and foundation exposure have not been resolved.

[0005] 3. Layered backfilling and compaction technology In pipeline trench and integrated utility tunnel construction, layered backfilling and compaction is a mature technology, typically employing a process of "layered paving—layered compaction—compaction degree testing." However, this technology is primarily used for trench backfilling, with the goal of compacting the backfill soil to the designed density to provide foundation support for the superstructure. Directly applying it to canal renovation presents technical obstacles: The process logic is reversed: pipeline trenches are excavated first and then backfilled, while channel renovation using the "backfill-excavate" mode is a "reverse excavation" logic. Existing technology does not address how to achieve internal soil circulation through backfill-reverse excavation. Insufficient forming accuracy: After backfilling, pipeline trenches are usually not excavated again, or only simple trench cleaning is carried out; while channel lining requires precise cross-sectional geometry and straight slopes, and the existing layered backfilling technology has not solved the problem of forming accuracy of reverse excavation. Mismatched tooling: The backhoe, grab bucket and other tooling used in pipeline construction cannot meet the precision requirements of one-time forming of the entire channel cross section, and it does not have the ability to be adjusted to adapt to different slope gradients.

[0006] 4. Tunnel and Underground Engineering Reverse Excavation Technology In the construction of tunnel bifurcation points and underground utility tunnels, the term "reverse excavation" exists, referring to a construction method that involves excavating in the reverse direction from the main tunnel to the branch tunnel. However, this technical scenario differs fundamentally from that of this application: The application scenarios are different: tunnel reverse excavation solves the problem of excavation approach under space-constrained conditions, rather than the problem of earthwork balance; The technical objectives are different: tunnel reverse excavation focuses on the stability of the excavation face and the efficiency of muck removal, and does not involve the cyclical process of "backfilling-reverse excavation-lining". The tooling is different: the reverse excavation of the tunnel uses the drill and blast method or a tunneling machine, which is completely different from the mechanical forming of the fixed shovel in this application.

[0007] 5. Channel lining formwork and pouring technology Current channel lining construction commonly employs a segmented casting method, with the base slab and slopes constructed separately: the base slab is typically cast continuously along the channel axis, while the slopes are constructed in segments using modular formwork, resulting in a time interval between the base slab and slope construction. This technique has inherent drawbacks: Weak interface: Stress concentration zones are easily formed at the joint between the base plate and the slope, and improper joint treatment can easily lead to leakage; Base surface deterioration: Delayed slope construction leads to prolonged exposure of the bottom slab edge, forming a "dry hard shell" that weakens interfacial bonding; Inefficient: Multi-stage formwork increases the time and labor costs associated with process connections, making it difficult to achieve rapid and continuous construction; Poor overall integrity: The construction joints formed by the multi-stage pouring become weak links in the channel seepage prevention system, which are prone to cracking and leakage in the long term.

[0008] In summary, traditional technologies have not yet resolved the following technical contradictions in the renovation of existing farmland irrigation channels using a combination of filling and excavation: 1. The contradiction between earthwork balance and construction efficiency Traditional full-line excavation results in a large amount of excavated soil being dumped off-site, while the fill section in semi-fill and semi-cut terrain requires the purchase of excavated soil from external sources, creating a wasteful "two-way transportation" pattern. Although sectional construction can reduce temporary land occupation, traditional technologies do not provide solutions for how to achieve internal circulation of excavated soil between sections and avoid transshipment to stockpiles.

[0009] 2. The contradiction between base surface quality and lining durability Common defects in farmland canal lining quality (hollowing, cracking, uneven settlement) stem from uneven and loose base layers. In traditional methods, the excavated section base surface is natural soil, while the filled section base surface is backfill soil. The significant differences in compaction degree and compression modulus between the two easily lead to differential settlement of the lining. Current technology does not address how to achieve uniform base layer quality across the entire cross-section through construction techniques and how to control the base surface exposure time to reduce moisture evaporation.

[0010] 3. The contradiction between molding accuracy and construction speed Manual slope trimming suffers from poor precision and low efficiency; mechanized slope cutting is efficient but struggles to adapt to the irregular cross-sections of existing channels. This is particularly true for semi-fill / semi-cut channels, where the soil quality differs between the fill and cut sections, and soil hardness varies significantly within the same cross-section. Conventional excavators are prone to over- or under-excavation, making it difficult to ensure uniform lining thickness. Existing equipment cannot balance forming precision and cross-sectional adaptability, and lacks the ability to quickly adjust to different slope gradients.

[0011] 4. The contradiction between the base-slope interface and the overall integrity. In traditional staged pouring processes, construction joints exist between the base slab and the slope. These joints are located in stress concentration zones and are prone to cracking and leakage. Delayed slope construction results in excessive exposure time at the edges of the base slab, forming a "dry hard shell" and weakening interfacial bonding. Traditional technologies have not provided feasible solutions for achieving integrated pouring of the base slab and slope to form a unified U-shaped cross-section, while controlling the exposure time of the base surface from forming to pouring within a reasonable window.

[0012] 5. The conflict between farmland protection and construction land occupation The renovation of farmland irrigation channels should minimize disturbance to arable land, but traditional methods require temporary land occupation such as soil dumps and construction access roads. Traditional technologies do not provide a systematic solution for completing construction within a limited working area and achieving "zero soil waste and zero soil borrowing". Summary of the Invention

[0013] The purpose of this invention is to solve at least one technical problem in the background art and to provide a method for reverse excavation construction of existing farmland irrigation channels with half-fill and half-cut.

[0014] To achieve the above objectives, the present invention provides a method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut sections, comprising: S1. Section division and clearing: Divide the channel to be renovated into several construction sections along the axis; remove tree roots, silt, humus and hidden bricks and stones in the channel to the stable natural soil layer. S2. Full-section layered backfilling and compaction: Backfill the entire cross-section of the construction section with soil and compact it in layers. The loose thickness of each layer is controlled at 25-30cm. Use a vibratory roller to compact it 3-5 times, and the compaction degree is ≥91%. Backfilling is stopped when it reaches 20-30cm above the designed bottom elevation of the reverse excavation, leaving room for compaction settlement, and forming a backfilled compaction zone. S3. Reverse Excavation and Shaping with a Shaped Shovel: An excavator equipped with a shaped shovel is used to perform a full-section reverse excavation of the backfill compaction area in one go, excavating to the designed channel bottom elevation to form the designed channel cross-section; the cross-sectional dimensions of the shaped shovel leave a 2cm margin for manual bottom cleaning compared to the designed channel excavation outline; the excavated soil is loaded onto trucks and transported to the next construction section for backfilling operations; S4. Base surface finishing and inspection: After the reverse excavation is formed, the excavated slope and bottom surface are manually finished, the loose soil is cleaned, and the base compaction degree is tested to be ≥91% to ensure that the slope is flat and straight and the base is dense. S5. Continuous Lining: After the base surface is repaired and inspected and qualified, the formwork is installed and the concrete is laid. The pouring adopts the continuous follow-up method of the base plate and the slope to ensure that the slope is poured before the initial setting of the base plate concrete. The skip-pour method is used in each construction section, and adjacent sections are poured in skip-pour. The exposure time of the back excavation base surface from the forming to the concrete pouring is controlled within 2-6 hours. If it exceeds this time, the surface shrinkage soil needs to be cleaned and cement slurry needs to be applied.

[0015] According to one aspect of the present invention, the length of the construction section is determined based on the matching relationship between the channel design cross-sectional dimensions and the amount of excavated earth produced and the amount of backfill required in the next construction section, so as to ensure that the earth produced by the excavation of a single construction section can be used entirely for the backfilling operation of the next construction section, and that the backfilling, compaction and excavation shaping operations within a single construction section can be completed within 24 hours.

[0016] According to one aspect of the invention, the roller used for the layered compaction has a travel speed of 2-3 km / h, the compaction direction is parallel to the channel axis, and the overlap width of adjacent compaction zones formed by the roller is ≥ 1 / 3 of the roller wheel width.

[0017] According to one aspect of the present invention, the compaction degree is tested using a ring cutter method or a nuclear density meter. One measuring point is randomly selected for every 100m³ to 500m³ of clay, and no less than five measuring points are selected for each layer. If the compaction degree does not meet the standard, it needs to be rolled again until it meets the standard before the next layer of backfilling is carried out.

[0018] According to one aspect of the present invention, the shaped shovel includes: a bucket connecting part and a section forming part; the bucket connecting part is a column, which is connected to the excavator bucket bolt hole by alloy steel bolts and is equipped with anti-loosening nuts; the section forming part is customized according to the channel design section size and includes a bottom plate horizontal section and a slope inclined section; The horizontal section of the base plate and the sloping section of the slope are detachably connected, and the inclination angle of the sloping section of the slope is adjustable.

[0019] According to one aspect of the present invention, the edge of the cross-section forming part of the shaped shovel is provided with a wear-resistant alloy steel cutting edge, and the cutting edge angle is adjusted according to the soil type of the backfill soil: 60-75° for clay and 45-60° for sandy loam.

[0020] According to one aspect of the present invention, the surface of the section forming part is provided with a polytetrafluoroethylene anti-friction coating or a stainless steel veneer.

[0021] According to one aspect of the invention, the reverse excavation includes: According to the design drawings, the total station or RTK instrument is used to lay out the excavation outline and mark the channel centerline, opening line and slope toe line. The level and RTK were used to monitor the excavation elevation in real time and control the excavation depth; The reverse excavation operation was carried out based on the calibration results and the excavation elevation.

[0022] According to one aspect of the invention, the channel cross-section is trapezoidal, rectangular or U-shaped, with a design flow rate of 0.5-10 m³ / s.

[0023] According to one aspect of the present invention, during the layered compaction process, a continuous compaction control system is adopted, in which an acceleration sensor and a GPS positioning module are installed on the roller to monitor the number of compaction passes, rolling trajectory and compaction degree in real time, and generate a full-section compaction cloud map; when local insufficient compaction degree is detected, the system automatically prompts to supplement compaction to ensure that the full-section compaction degree is uniform ≥91%.

[0024] According to one aspect of the present invention, addressing the difficulties in earthwork balance and farmland disturbance inherent in traditional full-line open-cut excavation methods, the present invention achieves internal earthwork balance through construction section division and cyclical transfer of earthwork between adjacent sections, completely eliminating the need for external disposal, purchase, and temporary stockpiling of earthwork, effectively protecting farmland resources. Secondly, addressing the common quality problems of soil shrinkage and lining hollowing and cracking caused by long exposure time of the base surface in traditional processes, the present invention strictly controls the exposure time of the excavated base surface from forming to concrete pouring to within 2-6 hours, maximizing the freshness and moisture content of the base surface, and significantly enhancing the bond strength between the concrete lining and the base layer. Furthermore, addressing the interface between the base slab and slope in traditional staged pouring processes... Addressing the inherent weaknesses and susceptibility to seepage, this invention employs a continuous follow-up pouring method for the base slab and slopes. This ensures that the slopes are poured before the initial setting of the base slab concrete, achieving a plastic bonding between the base slab and slopes. This completely eliminates cold joints and construction joints, creating a complete, seepage-proof channel. Furthermore, to address the issue of traditional excavators' rough slope cutting failing to guarantee cross-sectional accuracy, this invention uses a fixed-size shovel for one-time reverse excavation of the entire cross-section, leaving a 2cm margin for manual cleaning. This ensures both the geometric dimensional accuracy of the channel cross-section and the straightness of the slopes, while avoiding over-excavation and disturbance of the original soil. Simultaneously, the skip-pour method is used in each construction section, with adjacent sections poured in skip-pours. This effectively releases early shrinkage stress in the concrete, preventing shrinkage cracking of the lining. In summary, this invention systematically solves five major technical contradictions in the renovation of existing farmland channels under semi-fill and semi-cut terrain: earthwork balance, base quality, cross-sectional accuracy, bottom-slope interface, and farmland protection. It achieves the quality goals of zero earthwork waste, zero base exposure exceeding standards, and zero construction joints in lining, and significantly improves the durability and long-term operational reliability of channel projects.

[0025] According to one aspect of the present invention, addressing the resource waste and farmland disturbance caused by the disposal and purchase of excavated soil in traditional open-cut excavation methods, the present invention determines the section length based on the matching relationship between the channel design cross-sectional dimensions, the amount of excavated soil generated, and the backfill demand of the next construction section. This ensures that all excavated soil generated in a single construction section can be used for backfilling operations in the next section, achieving precise balance and internal recycling of excavated soil between adjacent sections. This completely eliminates the disposal, purchase, and temporary stockpiling of excavated soil, maximizing the protection of farmland resources. By constraining the section length with a 24-hour work cycle, the present invention ensures that the excavated soil generated in a single construction section can be used entirely for backfilling operations in the next section. Backfilling, compaction, and reverse excavation forming operations within the work section can be completed within 24 hours, enabling each construction section to form a daily cyclical operation mode. This provides a schedule guarantee for strictly controlling the exposure time of the reverse excavation base surface within 2-6 hours in the subsequent S5 step, avoiding problems such as prolonged exposure of the base surface, moisture evaporation, and soil shrinkage caused by excessively long sections and overdue operation cycles. At the same time, the precise matching of earthwork volume and the dual constraints of the 24-hour operation cycle enable the entire construction process to form a closed-loop management system with balanced excavation and filling and controllable timing, ensuring the efficient implementation of the reverse excavation process and the stable and controllable lining quality from the source.

[0026] According to one aspect of the present invention, the travel speed of the road roller is controlled within the range of 2-3 km / h. This ensures that the vibration compaction energy can be fully transferred to the soil, allowing soil particles to rearrange and compact within an effective time. It also avoids the low compaction efficiency caused by excessively slow speed or the insufficient compaction degree caused by excessively fast speed, thus achieving a synergistic balance between compaction efficiency and compacted quality. The rolling direction is strictly parallel to the channel axis, ensuring that the direction of the compaction force is consistent with the longitudinal stress distribution direction of the channel. This avoids lateral displacement of the soil and slope deformation that may be caused by transverse rolling, ensuring the overall stability of the backfill soil. The design of an overlap width of ≥1 / 3 of the wheel width between adjacent rolling zones eliminates the missed compaction area between wheel tracks, forming a continuous and uniform compaction zone across the entire backfill section. This avoids the compaction degree difference caused by local missed compaction, providing a uniformly dense backfill compaction zone without weak interlayers for subsequent reverse excavation processes.

[0027] According to one aspect of the present invention, the ring cutter method or nuclear density meter is used for testing. This retains the accuracy of the ring cutter method as a direct testing method while providing the option of rapid testing with a nuclear density meter, meeting the differentiated needs for testing efficiency and accuracy at different construction stages. For the sampling inspection scheme of setting one measuring point per 100m³ to 500m³ of clay and no less than five measuring points per layer, this ensures that the testing frequency accurately reflects the distribution of compacted material quality across the entire cross-section, while avoiding resource waste caused by over-testing, making the layout of the testing points statistically representative. The next layer of backfilling can only proceed after each layer has passed the testing. The sequential control system places compaction quality control at the level of each construction layer, preventing hidden defects caused by insufficient compaction in certain areas being covered by upper layers. This also prevents uneven settlement of the base surface caused by weak interlayers exposed during later backfilling. Furthermore, the requirement to re-compact areas that do not meet the compaction standard establishes a closed-loop quality control mechanism of inspection, feedback, and rectification. This ensures that the compaction degree of the entire backfill compaction zone reaches the design requirement of ≥91%, providing a dense, homogeneous, and high-strength working base surface for subsequent backfilling processes. This eliminates potential quality hazards such as lining hollowing, cracking, and uneven settlement caused by insufficient base compaction at the source.

[0028] According to one aspect of the present invention, the bucket connection adopts a column structure and is connected to the excavator bucket bolt holes via alloy steel bolts, equipped with anti-loosening nuts to ensure a rigid and reliable connection between the shovel and the excavator. This allows it to withstand significant cutting resistance and impact loads during high-intensity reverse excavation operations, avoiding safety hazards and construction interruptions caused by loosening or detachment. The cross-section forming section is customized according to the channel design cross-section dimensions, including a horizontal section of the bottom plate and an inclined section of the side slope, ensuring that the shape of the shovel perfectly matches the design cross-section. This achieves one-time excavation and forming of the entire cross-section, guaranteeing the levelness of the channel bottom and the straightness of the side slopes, providing a geometrically accurate working surface for subsequent lining construction. The shovel and bucket are detachably connected, and the horizontal section of the bottom plate and the sloping section of the slope are also detachably connected. This allows the shovel to be quickly replaced with the corresponding modules according to the size requirements of different channel cross-sections. One set of shovels can be adapted to various specifications of bottom plates and slope modules, which greatly reduces tooling costs and improves equipment utilization. More importantly, the inclination angle of the sloping section is adjustable, allowing the same set of shovels to adapt to channel slopes with different design slope ratios. This solves the problem of slope ratio changes that may occur in different sections of the same channel in semi-fill and semi-cut terrain, and avoids the cumbersome operation of frequently replacing the entire set of shovels due to slope ratio differences. This significantly improves the construction efficiency and cross-section adaptability of the reverse excavation process.

[0029] According to one aspect of the present invention, corresponding cutting edge angle ranges are set for different soil types based on their physical and mechanical properties, minimizing the cutting resistance when the cutting edge enters the soil and avoiding increased cutting edge wear or decreased cutting efficiency due to improper angles. For clay-type backfill, a larger cutting edge angle is used, causing the cutting edge to create a "splitting-stripping" effect on the soil, reducing the adhesion and accumulation of highly cohesive soil on the cutting edge surface and ensuring a smooth excavation section. For sandy loam-type backfill, a smaller cutting edge angle is used, causing the cutting edge to create a "cutting-separation" effect on the soil. The "effect" avoids lateral soil compression and slope disturbance caused by excessive angle, ensuring slope stability and straightness. The adjustable cutting edge angle allows the same set of shaped shovels to adapt to possible soil changes in different construction sections (such as soil differences between fill and cut sections in semi-fill and semi-cut terrain), eliminating the need for frequent shovel replacements due to soil changes and improving construction continuity. At the same time, the wear-resistant alloy steel cutting edge extends the service life of the shaped shovel, reduces the decrease in cross-sectional accuracy caused by cutting edge wear, and ensures the long-term stability of one-time full-section forming.

[0030] According to one aspect of the present invention, a total station or RTK is used to lay out the excavation outline, and the channel centerline, opening line, and slope toe line are marked, providing a precise spatial positioning benchmark for the reverse excavation operation. This ensures that the shovel can excavate according to the design axis, avoiding channel deviation or cross-sectional position errors caused by layout deviations. A level and RTK are used to monitor the excavation elevation in real time, and the excavation depth is dynamically controlled during the reverse excavation process, so that the shovel can accurately stop excavating at the design channel bottom elevation. This avoids both the disturbance of the original soil and the additional backfilling work caused by over-excavation, and the secondary trimming and insufficient lining thickness caused by under-excavation. By combining the layout and calibration results with real-time elevation monitoring, operators can monitor the deviation between the actual and designed positions of the shovels during excavation, adjust the excavator's actions in a timely manner, and ensure the geometric accuracy of the entire cross-section in one go. At the same time, the application of RTK technology achieves centimeter-level elevation positioning, providing a starting time reference for the precise control of the subsequent 2-6 hour base exposure time. In addition, the precise outline layout and elevation control make effective use of the 2cm manual bottom clearing allowance reserved by the shaping shovel. Manual finishing only requires the removal of surface loose soil to meet the design cross-section requirements, avoiding large-scale manual rework caused by excavation deviations.

[0031] According to one aspect of the present invention, the limitations of traditional point-based sampling inspection are overcome by installing an acceleration sensor and a GPS positioning module on the road roller. This enables real-time monitoring and recording of the number of compaction passes, rolling trajectory, and degree of compaction, upgrading compaction quality from post-continuous sampling inspection to continuous control throughout the entire process. This completely eliminates the possibility of missing local under-compacted areas due to sparse inspection points. By generating a full-section compaction cloud map, abstract compaction data is transformed into a visualized quality distribution map, allowing construction personnel to intuitively grasp the uniformity of compaction throughout the backfill compaction area, providing a basis for subsequent excavation procedures. Traceable quality records; when the system detects insufficient compaction in a localized area, it can automatically issue a prompt to replenish compaction, guiding operators to accurately replenish compaction in the under-compacted area, avoiding compaction defects caused by human error or missed compaction, and ensuring that the compaction degree of the entire cross section meets the design requirement of ≥91%; at the same time, the application of the continuous compaction control system forms a closed-loop control mechanism for monitoring, feedback and adjustment in the backfill compaction process, eliminating the potential for uneven settlement in the later stage caused by uneven compaction from the source, and providing a high-quality working surface with uniform density and stable bearing capacity for the reverse excavation base. Attached Figure Description

[0032] Figure 1 A flowchart illustrating a method for reverse excavation construction of lining existing farmland irrigation channels using a semi-fill and semi-cut method according to an embodiment of the present invention. Figure 2 The diagram schematically shows a front view of a shaping shovel according to one embodiment of the present invention. Detailed Implementation

[0033] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0034] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment".

[0035] Figure 1 This is a schematic flowchart illustrating a method for constructing a semi-fill / semi-cut existing farmland irrigation canal lining using reverse excavation, according to one embodiment of the present invention. Figure 1 As shown in this embodiment, the method for constructing a reverse excavation method for lining existing farmland irrigation channels using a combination of filling and excavation includes: S1. Section division and clearing: Divide the channel to be renovated into several construction sections along the axis; remove tree roots, silt, humus and hidden bricks and stones in the channel to the stable natural soil layer; S2. Full-section layered backfilling and compaction: Backfill the entire cross-section of the construction section with soil and compact it in layers. The loose thickness of each layer is controlled at 25-30cm. Use a vibratory roller to compact it 3-5 times, and the compaction degree is ≥91%. Stop backfilling when it reaches 20-30cm above the design excavation bottom elevation, and allow for compaction settlement to form a backfill compaction zone. S3. Reverse Excavation and Shaping with a Shaped Shovel: An excavator equipped with a shaped shovel is used to perform a full-section reverse excavation of the backfill compaction area in one go, excavating to the designed channel bottom elevation to form the designed channel cross-section; the cross-sectional dimensions of the shaped shovel leave a 2cm margin for manual bottom cleaning compared to the designed channel excavation outline; the excavated soil is loaded onto trucks and transported to the next construction section for backfilling operations; S4. Base surface finishing and inspection: After the reverse excavation is completed, the excavated slope and bottom surface are finished manually, loose soil is removed, and the base compaction degree is tested to be ≥91% to ensure that the slope is flat and straight and the base is dense. S5. Continuous Lining: After the base surface is repaired and inspected and qualified, the formwork is installed and the concrete is laid. The pouring adopts the continuous follow-up method of the base slab and the slope to ensure that the slope is poured before the initial setting of the base slab concrete. The skip-pour method is used in each construction section, and adjacent sections are poured in skip-pour. The exposure time of the back excavation base surface from the forming to the concrete pouring is controlled within 2-6 hours. If it exceeds this time, the surface shrinkage soil needs to be cleaned and cement slurry needs to be applied.

[0036] In this embodiment, firstly, addressing the difficulties in earthwork balance and farmland disturbance inherent in traditional full-line open-cut excavation methods, this invention achieves internal earthwork balance through construction section division and cyclical transfer of earthwork between adjacent sections, completely eliminating the need for external disposal, purchase, and temporary stockpiling of earthwork, effectively protecting farmland resources. Secondly, addressing the common quality problems of soil shrinkage and lining hollowing and cracking caused by long exposure time of the base surface in traditional processes, this invention strictly controls the exposure time of the excavated base surface from forming to concrete pouring to within 2-6 hours, maximizing the freshness and moisture content of the base surface, and significantly enhancing the bonding strength between the concrete lining and the base layer. Thirdly, addressing the interface between the base slab and slope in traditional staged pouring processes... Addressing the inherent weaknesses and susceptibility to seepage, this invention employs a continuous follow-up pouring method for the base slab and slopes. This ensures that the slopes are poured before the initial setting of the base slab concrete, achieving a plastic bonding between the base slab and slopes. This completely eliminates cold joints and construction joints, creating a complete, seepage-proof channel. Furthermore, to address the issue of traditional excavators' rough slope cutting failing to guarantee cross-sectional accuracy, this invention uses a fixed-size shovel for one-time reverse excavation of the entire cross-section, leaving a 2cm margin for manual cleaning. This ensures both the geometric dimensional accuracy of the channel cross-section and the straightness of the slopes, while avoiding over-excavation and disturbance of the original soil. Simultaneously, the skip-pour method is used in each construction section, with adjacent sections poured in skip-pours. This effectively releases early shrinkage stress in the concrete, preventing shrinkage cracking of the lining. In summary, this invention systematically solves five major technical contradictions in the renovation of existing farmland channels under semi-fill and semi-cut terrain: earthwork balance, base quality, cross-sectional accuracy, bottom-slope interface, and farmland protection. It achieves the quality goals of zero earthwork waste, zero base exposure exceeding standards, and zero construction joints in lining, and significantly improves the durability and long-term operational reliability of channel projects.

[0037] Furthermore, according to one embodiment of the present invention, the length of the construction section is determined based on the matching relationship between the channel design cross-sectional dimensions, the amount of excavated soil produced, and the backfill demand of the next construction section. This ensures that all the excavated soil from a single construction section can be used for backfilling in the next construction section, and that backfilling, compaction, and excavation shaping within a single construction section can be completed within 24 hours. In this embodiment, addressing the resource waste and farmland disturbance caused by the external disposal and purchase of excavated soil in the traditional full-line excavation mode, the present invention determines the section length based on the matching relationship between the channel design cross-sectional dimensions, the amount of excavated soil produced, and the backfill demand of the next construction section. This ensures that all the excavated soil from a single construction section can be used for backfilling in the next section, achieving precise balance and internal recycling of excavated soil between adjacent sections, completely eliminating the external disposal, purchase, and temporary stockpile occupation of excavated soil, and maximizing the protection of farmland resources. By constraining the section length with a 24-hour work cycle, this ensures that the excavated soil from a single construction section can be used for backfilling in the next section. Backfilling, compaction, and reverse excavation shaping within a section can be completed within 24 hours, enabling a daily cyclical operation mode for each construction section. This provides a schedule guarantee for strictly controlling the exposure time of the reverse excavation base surface to within 2-6 hours in the subsequent S5 step, avoiding problems such as prolonged exposure of the base surface, moisture evaporation, and soil shrinkage caused by excessively long sections and overdue operation cycles. Simultaneously, the precise matching of earthwork volume and the dual constraint of the 24-hour operation cycle create a closed-loop management system for the entire construction process, ensuring a balanced excavation and filling operation and a controllable time sequence. This guarantees the efficient implementation of the reverse excavation process and the stable and controllable quality of the lining from the source. Therefore, the section length determination method of this invention systematically solves the contradiction between earthwork balance and construction efficiency, laying a solid foundation for achieving the quality goals of zero earthwork waste and zero excessive base surface exposure.

[0038] Furthermore, according to one embodiment of the present invention, the roller used for layered compaction travels at a speed of 2-3 km / h, and the compaction direction is parallel to the channel axis. The overlap width of adjacent compaction zones formed by the roller is ≥ 1 / 3 of the roller wheel width. In this embodiment, the roller's travel speed is controlled within the range of 2-3 km / h. This ensures that the vibration compaction energy is fully transferred to the soil, allowing soil particles to rearrange and compact within an effective time. It also avoids the low compaction efficiency caused by excessively slow speed or the insufficient compaction degree caused by excessively fast speed, achieving a synergistic balance between compaction efficiency and compacted quality. The rolling direction is strictly parallel to the channel axis, ensuring that the direction of the compaction force is consistent with the longitudinal stress distribution direction of the channel. This avoids lateral displacement of the soil and slope deformation that may be caused by transverse rolling, ensuring the overall stability of the backfill soil. The design of an overlap width of ≥1 / 3 of the wheel width between adjacent rolling zones eliminates the missed compaction areas between wheel tracks, forming a continuous and uniform compaction zone across the entire backfill section. This avoids compaction degree differences caused by local missed compaction and provides a uniformly dense backfill compaction zone without weak interlayers for subsequent backfilling processes.

[0039] Furthermore, according to one embodiment of the present invention, the compaction degree is tested using the ring cutter method or a nuclear density meter. One testing point is randomly selected for every 100m³ to 500m³ of clay, with no fewer than five testing points per layer. If the compaction degree does not meet the standard, it must be re-compacted until it passes the test before proceeding to the next layer of backfill. In this embodiment, the ring cutter method or nuclear density meter is used for testing, which retains the accuracy of the ring cutter method as a direct testing method while providing the option of rapid testing with a nuclear density meter, meeting the differentiated needs for testing efficiency and accuracy at different construction stages. The sampling plan of setting one testing point per 100m³ to 500m³ of clay and no fewer than five testing points per layer ensures that the testing frequency accurately reflects the distribution of compaction quality across the entire cross-section, while avoiding resource waste caused by excessive testing, making the layout of testing points statistically representative. The process control of allowing the next layer of backfill only after each layer has passed the test is implemented. This system places compaction quality control at the level of each construction layer, preventing hidden defects caused by insufficient compaction being covered by upper layers and avoiding uneven settlement of the base surface due to weak interlayers exposed during later excavation. Simultaneously, the requirement to re-compact areas that do not meet the compaction standard establishes a closed-loop quality control mechanism of inspection, feedback, and rectification. This ensures that the compaction degree of the entire backfill compaction zone reaches the design requirement of ≥91%, providing a dense, homogeneous, and high-strength working base surface for subsequent excavation processes. It eliminates potential quality hazards such as lining hollowing, cracking, and uneven settlement caused by insufficient base compaction at the source.

[0040] Furthermore, Figure 2 This schematic diagram shows a front view of a shaping shovel according to one embodiment of the present invention. Figure 2As shown, in this embodiment, the shaped shovel includes: a bucket connecting part 1 and a section forming part 2; the bucket connecting part 1 is a column, which is connected to the bucket bolt hole of the excavator by alloy steel bolts and is equipped with anti-loosening nuts; the section forming part 2 is customized according to the channel design section size, and the section forming part 2 is detachably connected to the bucket connecting part 1. The section forming part 2 includes a bottom plate horizontal section 3 and a slope inclined section 4; The horizontal section 3 of the base plate and the sloping section 4 of the slope are detachably connected, and the inclination angle of the sloping section 4 is adjustable. In this embodiment, the inclination angle adjustment range of the sloping section 4 is, for example, in the range of 0-90°, which is achieved by changing the bolt connection hole position or by hinge pin connection, etc., to adapt to slope gradients of 1:0.5 to 1:2.

[0041] In this embodiment, the bucket connection part 1 adopts a column structure and is connected to the excavator bucket bolt holes via alloy steel bolts, equipped with anti-loosening nuts to ensure a rigid and reliable connection between the shovel and the excavator. This allows it to withstand significant cutting resistance and impact loads during high-intensity reverse excavation operations, preventing safety hazards and construction interruptions caused by loosening or detachment. The section forming part 2 is customized according to the channel design cross-sectional dimensions, including a horizontal bottom section 3 and a sloping side section 4, ensuring the shovel's outline perfectly matches the design cross-section. This achieves one-time excavation and forming of the entire cross-section, guaranteeing the levelness of the channel bottom and the straightness of the slope, providing a geometrically accurate working surface for subsequent lining construction. In this embodiment, the section forming part 2 is connected to the bucket. The detachable connection of section 1 and the detachable connection of the horizontal section 3 of the bottom plate and the sloping section 4 of the slope allows the fixed shovel to be quickly replaced with the corresponding module according to the size requirements of different channel cross-sections. One set of shovel body can be adapted to various specifications of bottom plate and slope modules, which greatly reduces tooling costs and improves equipment utilization. More importantly, the inclination angle of the sloping section is adjustable, which allows the same set of fixed shovels to adapt to channel slopes with different design slope ratios (such as 1:1.5, 1:1.75, 1:2.0, etc.). This solves the problem of slope ratio changes that may exist in different sections of the same channel in semi-fill and semi-cut terrain, and avoids the cumbersome operation of frequently replacing the entire set of shovels due to slope ratio differences. This significantly improves the construction efficiency and cross-section adaptability of the reverse excavation process.

[0042] Furthermore, according to one embodiment of the present invention, the edge of the cross-section forming part 2 of the shaped shovel is provided with a wear-resistant alloy steel cutting edge, and the cutting edge angle is adjusted according to the backfill soil type: 60-75° for clay and 45-60° for sandy loam. In this embodiment, based on the physical and mechanical properties of different soil types (clay has high cohesion and a large internal friction angle, while sandy loam has low cohesion and a small internal friction angle), corresponding cutting edge angle ranges are set (60-75° for clay and 45-60° for sandy loam) to minimize the cutting resistance when the cutting edge cuts into the soil, avoiding increased cutting edge wear or decreased cutting efficiency due to improper angle; for clay-type backfill, a larger cutting edge angle (60-75°) is used, so that the cutting edge forms a "splitting-peeling" effect on the soil, reducing the adhesion and accumulation of highly cohesive soil on the cutting edge surface, and ensuring a smooth and flat excavation section; for sandy loam backfill, a larger cutting edge angle (60-75°) is used. Using a smaller cutting edge angle (45-60°) creates a "cutting-separation" effect on the soil, avoiding lateral soil compression and slope disturbance caused by excessive angles, thus ensuring slope stability and straightness. The adjustable cutting edge angle allows the same set of shaped shovels to adapt to possible soil changes in different construction sections (such as the difference in soil quality between fill and cut sections in semi-fill / semi-cut terrain), eliminating the need for frequent shovel replacements due to soil changes and improving construction continuity. At the same time, the wear-resistant alloy steel cutting edge extends the service life of the shaped shovel, reduces the decrease in cross-sectional accuracy caused by cutting edge wear, and ensures the long-term stability of one-time full-section forming.

[0043] Furthermore, according to one embodiment of the present invention, the surface of the section forming part is provided with a polytetrafluoroethylene (PTFE) anti-friction coating or a stainless steel cladding. In this embodiment, addressing the technical problem of soil easily adhering to the shovel surface during back excavation in cohesive soil, leading to rough forming section and increased cutting resistance, the PTFE coating utilizes its extremely low coefficient of friction (≤0.1) and excellent non-adhesive properties to form a sliding interface between the soil and the shovel surface, effectively preventing the accumulation and adhesion of clay on the shovel surface, ensuring that the shovel surface remains clean after each excavation, thereby guaranteeing the continuity and flatness of the section forming in one step; the stainless steel cladding, through its smooth surface characteristics and high wear resistance, reduces the frictional resistance between soil particles and the shovel surface in sandy loam or soil conditions with high sand content, reducing excavator energy consumption, and also resists the abrasive wear of quartz particles in the soil on the shovel surface. The friction reduction measures significantly extend the service life of the section forming part; the implementation of friction reduction measures greatly reduces the flow resistance of soil on the surface of the excavator, allowing the soil to slide smoothly along the curved surface of the excavator and accumulate in the bucket, reducing soil retention and accumulation on the excavator surface, and improving the single-pass soil removal efficiency and loading efficiency of reverse excavation operations; at the same time, the application of coating or stainless steel cladding avoids the deformation of the excavator profile caused by soil adhesion, ensuring that the shape and size of the shaped excavator remain stable during long-term use, and ensuring that the precision control of the reserved 2cm manual bottom cleaning allowance does not fail due to excavator wear or deformation; in addition, the friction reduction design also reduces the cutting load of the excavator during reverse excavation, reduces equipment energy consumption and hydraulic system losses, and achieves the additional effect of energy saving and consumption reduction.

[0044] Furthermore, according to one embodiment of the present invention, reverse excavation includes: According to the design drawings, the total station or RTK instrument is used to lay out the excavation outline and mark the channel centerline, opening line and slope toe line. The level and RTK were used to monitor the excavation elevation in real time and control the excavation depth; The reverse excavation operation was carried out based on the calibration results and the excavation elevation.

[0045] In this embodiment, a total station or RTK is used to lay out the excavation outline, marking the channel centerline, opening line, and slope toe line. This provides a precise spatial positioning benchmark for the reverse excavation operation, ensuring that the shovel can excavate according to the design axis and avoiding channel deviation or cross-sectional position errors caused by layout errors. A level and RTK are used to monitor the excavation elevation in real time, dynamically controlling the excavation depth during the reverse excavation process. This ensures that the shovel can accurately stop excavating at the designed channel bottom elevation, avoiding both over-excavation causing disturbance to the original soil and additional backfilling work, and under-excavation causing secondary trimming and insufficient lining thickness. The combination of sample calibration results and real-time elevation monitoring allows operators to monitor the deviation between the actual and designed positions of the shovel during excavation, enabling timely adjustments to the excavator's actions and ensuring geometric accuracy of the entire cross-section formed in one go. Simultaneously, the application of RTK technology achieves centimeter-level elevation positioning, providing a starting time reference for precise control of the subsequent 2-6 hour base exposure time. Furthermore, precise contour line layout and elevation control effectively utilize the 2cm manual bottom clearing allowance reserved by the shovel; manual finishing only requires removing surface loose soil to meet the design cross-section requirements, avoiding large-scale manual rework due to excavation deviations.

[0046] Furthermore, according to one embodiment of the present invention, the channel cross-section is trapezoidal, rectangular or U-shaped, and the design flow rate is 0.5-10 m³ / s.

[0047] Furthermore, according to one embodiment of the present invention, a continuous compaction control system is adopted during the layered compaction process. An accelerometer and a GPS positioning module are installed on the roller to monitor the number of compaction passes, rolling trajectory, and compaction degree in real time, generating a full-section compaction cloud map. When insufficient compaction degree is detected in a localized area, the system automatically prompts for additional compaction to ensure that the uniformity of compaction degree across the entire cross-section is ≥91%. In this embodiment, the limitations of traditional point-based sampling inspection are overcome. The installation of an accelerometer and a GPS positioning module on the roller enables real-time monitoring and recording of the number of compaction passes, rolling trajectory, and compaction degree. This upgrades compaction quality from post-continuous sampling inspection to continuous control throughout the entire process, completely eliminating potential omissions of under-compacted areas due to sparse inspection points. By generating a full-section compaction cloud map, abstract compaction data is transformed into a visualized quality distribution map, allowing construction personnel to intuitively grasp the uniformity of compaction degree across the entire backfill compaction area, providing a traceable basis for subsequent excavation procedures. The system maintains a traceable quality record; when it detects insufficient compaction in a localized area, it can automatically issue a prompt to replenish the compaction, guiding operators to accurately replenish the under-compacted area. This avoids compaction defects caused by human error or missed compaction, ensuring that the compaction degree of the entire cross-section meets the design requirement of ≥91%. At the same time, the application of the continuous compaction control system creates a closed-loop control mechanism for monitoring, feedback, and adjustment in the backfill compaction process, eliminating the potential for uneven settlement in the later stages caused by uneven compaction. This provides a high-quality working surface with uniform density and stable bearing capacity for the reverse excavation base.

[0048] According to the above-described scheme of this invention, through systematic innovation in layered backfilling, shaped excavation, and synchronous skip-fill lining, this invention achieves five major technological breakthroughs in the transformation of semi-fill and semi-excavation channels: Section division and cyclical earthwork transportation completely eliminate the need for external disposal, purchase, and temporary stockpiling of earthwork; full-section layered compaction followed by reverse excavation forms a uniform, high-density base surface, eliminating differential settlement; shaped excavation ensures geometric accuracy and slope straightness by forming the entire cross-section in one go with a reserved allowance; continuous pouring of the base slab and slope before initial setting achieves plastic bonding and eliminates construction cold joints; strict control of base surface exposure time, with cement slurry applied for remedies if the exposure time exceeds the limit, and the skip-fill method is used to release shrinkage stress. This invention systematically solves five major technical contradictions: earthwork balance, base surface quality, forming accuracy, interface integrity, and farmland protection, achieving the quality goals of zero earthwork waste, zero base surface exposure exceeding standards, and zero construction joints in the lining, significantly improving channel durability and operational reliability.

[0049] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this application.

[0050] It should be understood that the sequence number of each step in the invention and its embodiments does not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A method for constructing lining existing farmland irrigation channels using a semi-fill and semi-excavation method, characterized in that: include: S1. Section division and clearing: Divide the channel to be renovated into several construction sections along the axis; remove tree roots, silt, humus and hidden bricks and stones in the channel to the stable natural soil layer; S2. Full-section layered backfilling and compaction: Backfill the entire cross-section of the construction section with earth and compact it in layers. The loose thickness of each layer is controlled within the first threshold range. The vibratory roller is used to compact the soil multiple times, and the compaction degree is ≥ the second threshold. Backfilling is stopped when the third threshold is above the design excavation bottom elevation. Compaction settlement is reserved to form a backfill compaction zone. S3. Reverse Excavation and Shaping with a Shaped Shovel: An excavator equipped with a shaped shovel is used to perform a full-section reverse excavation of the backfill compaction area in one go, excavating to the designed channel bottom elevation to form the designed channel cross-section; the cross-sectional dimensions of the shaped shovel are reserved with a fourth threshold margin for manual bottom cleaning compared to the designed channel excavation outline; the excavated soil is loaded onto trucks and transported to the next construction section for backfilling operations; S4. Base surface finishing and inspection: After the reverse excavation is completed, the excavated slope and bottom surface are finished manually, loose soil is removed, and the base compaction degree is tested to be ≥ the second threshold to ensure that the slope is flat and straight and the base is dense. S5. Continuous Lining: After the base surface is repaired and inspected and qualified, the formwork is installed and the concrete is lined. The pouring adopts the continuous follow-up method of the base slab and the slope to ensure that the slope is poured before the initial setting of the base slab concrete. The skip-pour method is used in each construction section, and adjacent sections are poured in skip-pour. The exposure time of the back excavation base surface from the forming to the concrete pouring is controlled within the fifth threshold range. If it exceeds this time, the surface drying shrinkage soil needs to be cleaned and cement slurry is applied.

2. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 1, characterized in that, The length of the construction section is determined based on the channel design cross-sectional dimensions and the matching relationship between the amount of excavated soil produced and the amount of backfill required for the next construction section. This ensures that all the excavated soil produced in a single construction section can be used for the backfilling work in the next construction section, and that the backfilling, compaction, and excavation shaping work within a single construction section can be completed within 24 hours.

3. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 1, characterized in that, The roller used for the layered compaction has a travel speed of 2-3 km / h, and the rolling direction is parallel to the channel axis. The overlap width of adjacent compaction zones formed by the roller is ≥ 1 / 3 of the roller wheel width.

4. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 1, characterized in that, The compaction degree is tested using the ring cutter method or a nuclear density meter. One measuring point is randomly selected for every 100m³ to 500m³ of clay, and no less than five measuring points are required for each layer. If the compaction degree does not meet the standard, it needs to be rolled again until it is qualified before the next layer is backfilled.

5. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 1, characterized in that, The shaped shovel includes: a bucket connecting part and a section forming part; the bucket connecting part is a column, which is connected to the excavator bucket bolt hole by alloy steel bolts and equipped with anti-loosening nuts; the section forming part is customized according to the channel design cross-sectional dimensions, including a bottom plate horizontal section and a slope inclined section; The horizontal section of the base plate and the sloping section of the slope are detachably connected, and the inclination angle of the sloping section of the slope is adjustable.

6. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 5, characterized in that, The edge of the shaped section of the shovel is provided with a wear-resistant alloy steel cutting edge, and the cutting edge angle is adjusted according to the soil type of the backfill: 60-75° for clay and 45-60° for sandy loam.

7. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 5, characterized in that, The surface of the cross-section forming part is provided with a polytetrafluoroethylene anti-friction coating or a stainless steel veneer.

8. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 1, characterized in that, The reverse excavation includes: According to the design drawings, the total station or RTK instrument is used to lay out the excavation outline and mark the channel centerline, opening line and slope toe line. The level and RTK were used to monitor the excavation elevation in real time and control the excavation depth; The reverse excavation operation was carried out based on the calibration results and the excavation elevation.

9. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 1, characterized in that, The channel cross-section is trapezoidal, rectangular, or U-shaped, with a design flow rate of 0.5-10 m³ / s.

10. The method for reverse excavation construction of existing farmland irrigation canals with semi-fill and semi-cut as described in claim 1, characterized in that, During the layered compaction process, a continuous compaction control system is adopted. An acceleration sensor and a GPS positioning module are installed on the roller to monitor the number of compaction passes, rolling trajectory and compaction degree in real time, and generate a full-section compaction cloud map. When insufficient local compaction degree is detected, the system automatically prompts for additional compaction to ensure that the full-section compaction degree is uniform and ≥ the second threshold.

Images