Railway culvert wing wall stepped chiseling and inlaying heightening lengthening construction method

Abstract

The invention discloses a railway culvert wing wall step-type chiseling and inlaying heightening lengthening construction method, and belongs to the technical field of existing railway line structure transformation construction. The method aims at solving the technical problems that an existing wing wall foundation needs to be wholly broken in traditional construction, disturbance to a line slope is large, and the safety risk is high. The method is characterized by comprising the steps that automatic monitoring equipment is installed on a road shoulder; measuring and marking a stepped chiseling line and a turning opening vertical inlaying wide line on the existing wing wall; steel rail piles are driven into the side slope for protection, and operation space is excavated in a layered mode; carrying out vertical cutting and stepped horizontal cutting along the marking line by adopting a rope saw; and finally, chiseling and grooving the cutting step surface, chiseling off part of the wing wall foundation, installing steel bars and pouring concrete to form a vertical inlay complement combined with the existing wing wall and a heightened side wall. The method is mainly used for carrying out lengthening transformation construction on the existing railway culvert on the premise that the railway operation safety is ensured.

Description

Technical Field

[0001] This invention belongs to the field of construction technology for the renovation of existing railway lines. More specifically, this invention relates to a method for the step-type chiseling, patching, heightening, and extension of the wing wall of a railway culvert. Background Technology

[0002] When extending or renovating existing culverts along railway lines, it is usually necessary to raise and extend the existing wing walls. Traditional construction methods often involve the complete or large-scale demolition of the existing wing wall foundation to make room for the new sidewall structure. This approach significantly disturbs the roadbed slope on which the wing wall is attached, potentially jeopardizing its immediate stability and posing a potential threat to the track geometry of adjacent railway lines. Due to the high density of railway traffic and short track maintenance windows, this large-scale excavation and disturbance method carries high safety risks and causes significant disruption to operations, making it extremely difficult to implement. Furthermore, achieving a reliable connection between the old and new structures within a limited timeframe, without damaging the main load-bearing components of the existing structure, has always been a technical challenge. Improper handling can easily lead to a weak interface between the newly poured, raised sidewall and the old wing wall, affecting the structural integrity and long-term durability. Therefore, finding a method for extending wing walls that can minimize disturbance to the roadbed slope, avoid the overall demolition of the foundation, and ensure a firm connection between the old and new structures is an urgent problem to be solved in existing railway line renovation projects. Summary of the Invention

[0003] One object of the present invention is to address at least the aforementioned deficiencies and to provide at least the advantages that will be described later.

[0004] This invention provides a method for the stepped removal and patching of railway culvert wing walls, which can preserve part of the original structure through stepped cutting without completely destroying the existing wing wall foundation. Combined with patching and anchoring measures, it significantly increases the bonding area and shear resistance of the new and old concrete, thereby safely and reliably extending and raising the culvert sidewalls. At the same time, it minimizes disturbance to the existing railway subgrade slope and ensures the safety of railway operation.

[0005] This invention provides a method for the stepped removal, patching, heightening, and extension of the wing wall of a railway culvert, comprising the following steps: The first step is to install automatic monitoring equipment at a secure location on the road shoulder near the culvert extension site to monitor the displacement of the roadbed and track during construction. The second step is to measure and mark the stepped chisel lines and the vertical filling lines at the bends on the existing wing walls according to the design drawings. The third step is to drive steel rail piles into the roadbed slope excavation location where the existing wing wall needs to be removed for protection, and then carry out slope excavation to create working space for cutting and pouring. The fourth step is to use a wire saw to vertically cut the existing wing wall and capstone along the marked corner vertically; then, along the marked stepped chisel lines, use a wire saw to horizontally cut the existing wing wall in a stepped manner. The fifth step involves roughening the cut step surface and chiseling out a groove 10-20 mm deep and 30-40 mm wide at 100 mm intervals; then chiseling away 200 mm deep from the existing wing wall foundation at the corresponding positions of the bend and flared sections; then installing reinforcing bars on the treated step surface, grooves, and chiseled areas of the wing wall foundation, and anchoring the reinforcing bars to the existing wing wall; finally, pouring concrete to form a vertical insert and heightened side wall that is integrated with the existing wing wall.

[0006] Preferably, the second step specifically includes: using a total station to preliminarily mark the positions of the stepped chisel lines and the vertical filling lines at the bends on the existing wing wall and capstone surface according to the coordinates of the design drawings; after the lines are determined, using an electric hammer, drill holes with a depth of 15 mm to 20 mm every 500 mm to 1000 mm along the marked line path, and embed metal marker nails with reflective coatings in the holes; finally, use elastic paint to snap or brush along the connecting lines of the metal marker nails to form a continuous visible marked line with a width of 5 mm to 8 mm.

[0007] Preferably, the third step specifically includes: arranging two rows of rail piles at a center-to-center spacing of 1.5 to 2.0 meters in a direction parallel to the edge line of the existing roadbed slope to form a double-layer support; using a vibratory hammer to vertically drive the rail piles into the roadbed slope soil, controlling the driving depth between 3 and 5 meters; when the penetration rate of the vibratory hammer is less than 50 mm within 1 minute or encounters a rigid obstacle, immediately stop driving the rail pile; and drill a first guide hole with a diameter of 100 to 150 mm within 0.75 to 1.0 meters on each of its adjacent sides, with the depth of the first guide hole exceeding the top of the obstacle by 0.5 to 1.0 meters; then injecting M30 grade cement mortar into the first guide hole; after the strength of the grout reaches 10 MPa, fixing the original rail pile to the grout; after completing the rail pile layout... Then, the tops of adjacent rail piles in the same row are horizontally connected, and diagonal channel steel scissor bracing is welded between the two layers of rail piles to form a spatial truss-type joint support structure. After the protection structure is completed, the slope earthwork is excavated in layers, with each layer having a thickness of 0.8 to 1.2 meters. The net distance between the excavated slope surface and the rail piles is maintained at 0.3 to 0.5 meters. During the excavation process, a total station is used to monitor the horizontal displacement of the top of the rail piles in real time. When the cumulative horizontal displacement of the pile top caused by a single excavation layer exceeds 5 millimeters, the excavation is immediately suspended, and a layer of C20 fine stone concrete with a thickness of not less than 50 millimeters is laid on the excavation surface of that layer for temporary sealing. The next layer of excavation is carried out after the concrete strength reaches 70% of the design value. The final excavation surface should be 1.2 to 1.8 meters larger than the stepped chisel line of the wing wall.

[0008] Preferably, the fourth step specifically includes: when performing vertical cutting, firstly, at one end of the marked bend vertically, drill a second guide hole penetrating the thickness of the existing wing wall; pass the cutting rope of the wire saw through the second guide hole and tension it to form a closed cutting loop; start the wire saw to make the first cut along the marked line, controlling the depth of the first cut to one-third to one-half of the wall thickness, forming a guide groove; after completing the first cut, adjust the tension and cutting speed of the wire saw, and make a second cut along the same guide groove until the existing wing wall and capstone are completely cut through, forming a complete vertical cut surface; when performing vertical and... Throughout the horizontal cutting process, a circulating water cooling system with a pressure regulating valve and atomizing nozzles is configured. The outlet of this system is aligned with the contact point between the cutting rope or cutting saw blade and the wall. The cooling water pressure is maintained between 0.2 MPa and 0.4 MPa. Fine stone powder with a particle size of less than 0.1 mm is mixed in the water flow. The amount of the powder can be 0.5% to 1% by weight of the cooling water to enhance the cooling and lubrication effect and suppress dust. After all vertical cutting is completed, stepped horizontal cutting is carried out. Horizontal cutting should start from the top of the wing wall and proceed layer by layer downwards. During cutting, ensure that the guide wheels of the cutting equipment are in close contact with the completed upper-layer cut surface or the original wall surface.

[0009] Preferably, the stepped horizontal cutting also includes the following steps: Before starting each layer of horizontal cutting, a rebound hammer is used to test the strength of the existing wing wall below the proposed cutting path. At least three test areas are selected, and 16 points are tested in each test area. When the average rebound value of a certain test area is less than 20 or the dispersion is greater than 5, a row of threaded steel bars with a diameter of 12 mm and a length of 300 mm is pre-embedded as temporary reinforcement at a depth of 200 mm below the horizontal cutting line of that layer. The exposed part is welded and poured with the reinforcement of the heightened side wall in subsequent construction. When performing horizontal cutting, a stepped retreat is adopted. The process is as follows: After each step-height horizontal cut is completed, a crack monitoring instrument is immediately used to scan the surface of the horizontal cut surface and the adjacent existing wall to record the width and length of any new or extended cracks. If a crack is found to be wider than 0.3 mm and longer than 200 mm, a stress relief hole with a diameter of 30 mm is drilled at the end of the crack, with a depth exceeding 50 mm from the crack tip, and epoxy resin grout is injected into the hole. After all step-type horizontal cuts are completed, all cut surfaces are cleaned with a high-pressure water gun at a pressure of not less than 8 MPa to remove the mud, powder, and loose fine particles adhering to the surface.

[0010] Preferably, when making horizontal cuts, a layered, stepped retreat method is adopted, which means that at the same elevation, a full-length horizontal cut is first completed along the length of the wing wall to form a horizontal cross section, and then the next layer of horizontal cuts is made at the next step height. The vertical distance between two adjacent horizontal cut surfaces is the step height.

[0011] Preferably, the fifth step specifically includes: roughening all the stepped surfaces formed by cutting, with the impact direction at an angle of 45 to 60 degrees to the stepped surface, and the roughening depth being sufficient to expose the surface aggregate; along the stepped surface, chiseling a horizontal groove at 100 mm intervals, the groove being 10 mm deep and 35 mm wide, with the length of the groove extending through the width of the entire stepped surface; after completing the stepped surface treatment and cleaning up the debris, chiseling away 200 mm deep from the existing wing wall foundation at the corresponding positions of the bend and flared sections, removing all loose particles and dust from the roughened stepped surface, the grooves, and the chiseled area of ​​the wing wall foundation; during the reinforcement installation, first hoisting the prefabricated skeleton of the vertical main reinforcement and horizontal distribution reinforcement of the heightened side wall into place as a whole, then inserting one end of the L-shaped structural reinforcement used for pouring the vertical inlay into the chiseled area of ​​the wing wall foundation, and binding the other end to the reinforcement skeleton of the heightened side wall; before pouring concrete, sprinkling water on the cleaned stepped surface, grooves, and chiseled area of ​​the foundation.

[0012] Preferably, the reinforcement installation also includes: before the reinforcement cage of the heightened side wall is in place, first, on the stepped surface of the existing wing wall, corresponding to the design position of the vertical main reinforcement, use an electric hammer to drill holes with a diameter 4 mm to 6 mm larger than the diameter of the main reinforcement, and a hole depth of 150 mm; inject epoxy resin adhesive into the holes, and then insert the end of the vertical main reinforcement of the heightened side wall into the holes, ensuring an insertion depth of not less than 120 mm; after the epoxy resin has cured, tie and fix the remaining part of the reinforcement cage of the heightened side wall; for the L-shaped structural reinforcement installed in the area where the foundation of the wing wall is removed, weld a short horizontal steel bar with a length of not less than 200 mm to the outside of the corner between its vertical and horizontal sections, and weld the short steel bar to the L-shaped structural reinforcement to form a triangular support.

[0013] Preferably, the concrete pouring process includes: starting from the bottom of the area to be removed from the wing wall foundation, pouring the concrete in layers continuously, with each layer not exceeding 500 mm in thickness; when the concrete reaches the lower edge of the transverse groove, a 30 mm diameter immersion vibrator is used to focus on compacting the area inside the groove, inserting the vibrator into the bottom of the groove and slowly withdrawing it to ensure that the groove is completely and densely filled with concrete; when the concrete reaches the height of the step surface, pouring is temporarily stopped, and the concrete surface at the step surface junction is roughened with a wooden trowel, and then the concrete for the raised side wall portion is poured upwards; after all the concrete is poured, a permeable geotextile is covered on the top surface of the raised side wall, and drip irrigation is used to keep the geotextile continuously moist for a curing time of not less than 7 days.

[0014] Preferably, after forming the vertical insert and the heightened sidewall, the process also includes the following steps: constructing a cover plate on top of the heightened sidewall; constructing the wing wall and foundation of the new extension section in the direction of the existing culvert outside the route; and finally, constructing the waterproof layer of the entire extension culvert and backfilling the culvert backfill.

[0015] The present invention has at least the following beneficial effects: This invention preserves part of the original structure through stepped cutting, minimizing excavation and disturbance to the existing railway embankment slope. Combined with dynamic support and real-time monitoring of rail piles, it significantly reduces the risk to the operational safety of adjacent railway tracks, achieving safe construction with minimal disturbance in complex environments. Through a series of stepped surfaces, regular transverse grooves, and a structural design that anchors new concrete into the existing foundation, combined with interface roughening, slag removal, and rebar installation, the bonding area and mechanical interlocking force of the new and old materials are greatly increased, ensuring that the raised sidewall and the old wing wall form a stable whole, jointly bearing the load. Addressing the challenges of underground obstacles and uneven strength of old masonry rubble in karst development areas, this method integrates proactive control measures such as intelligent obstacle handling, pre-cutting strength testing and pre-reinforcement, and immediate post-cutting crack repair, effectively ensuring the integrity of the construction process and the remaining structure. In addition, this method organically combines automated monitoring, line setting, controlled cutting, systematic connection and pouring and curing, forming a standardized, reusable and efficient construction process, which greatly improves project quality and work efficiency, shortens the construction period, and provides a reliable technical reference for similar existing line renovation projects.

[0016] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the elevation of the construction and renovation of the wing wall of the railway culvert described in this invention, involving the stepped removal, patching, heightening, and extension. Figure 2 This is a schematic diagram of the cross-section of the construction and modification of the stepped removal, patching, heightening and extension of the wing wall of the railway culvert according to the present invention; Among them, the existing wing wall foundation 1; the existing wing wall 2; the channel steel shear brace 3; the vertical insert 4; the cap stone 5; the stepped surface 6; the heightened side wall 7; the cover plate 8; the newly built extended wing wall 9; the existing wing wall foundation at the location of the chiseled-out section 10; the rail pile 11; and the excavation face 12. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0019] It should be noted that terms such as “having,” “comprising,” and “including” used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0020] This invention provides a method for the stepped removal, patching, heightening, and extension of the wing wall of a railway culvert, comprising the following steps: The first step is to install automatic monitoring equipment at a secure location on the road shoulder near the culvert extension site to monitor the displacement of the roadbed and track during construction. The second step is to measure and mark the stepped chisel lines and the vertical filling lines at the bends on the existing wing wall 2 according to the design drawings. The third step is to drive steel rail piles 11 into the roadbed slope excavation location where the existing wing wall needs to be removed for protection, and then carry out slope excavation to create working space for cutting and pouring. The fourth step is to vertically cut the existing wing wall 2 and cap stone 5 along the marked corner vertically and fill the width line; then, along the marked stepped chisel line, use a wire saw or stone cutting machine to horizontally cut the existing wing wall 2 in a stepped manner. The fifth step involves roughening the cut step surface 6 and chiseling out a groove 10-20 mm deep and 30-40 mm wide at 100 mm intervals. Next, 200 mm deep sections of the existing wing wall foundation at the corresponding corner and flared section locations are removed (i.e., 200 mm deep removal of the existing wing wall foundation at the corner and flared section locations). Then, reinforcing bars are installed on the treated step surface 6, grooves, and the removed wing wall foundation areas, and these reinforcing bars are anchored to the existing wing wall. Concrete is then poured to form a vertical filler 4 and a raised side wall 7 integrated with the existing wing wall. The "corner" mentioned in this text refers to two key areas on the existing wing wall that require vertical cutting to form the filler width: one is the end of the vertical section near the culvert opening, and the other is the far end of the flared section extending outwards (towards the roadbed). The flared section refers to the inclined wall portion of the existing wing wall extending outwards from the corner of the culvert opening and connecting with the roadbed slope. The existing wing wall foundation 10 at the flared section refers to the original foundation below the inclined wall. The vertical patching line at the bend is the position line marked on the outer facade of the existing wing wall 2, used to determine the thickness and vertical position of the new concrete sidewall. After construction along this line, a vertical patch 4 will be formed that is tightly integrated with the existing wing wall (the vertical patch 4 is like "attaching" a new thickened sidewall to the outside of the existing wing wall, achieving horizontal widening and connection). The vertical patch 4 and the upper stepped heightened sidewall 7 are cast together to form a complete reinforced concrete heightened sidewall. There is no need to demolish the existing wing wall foundation 1 and the existing wing wall 2 as a whole.

[0021] When extending or renovating culverts on existing railway lines, traditional construction methods typically require the complete or large-scale mechanical demolition of the existing wing walls and their foundations that affect the extension, in order to make room for the new wing wall structure. This method involves a large excavation area, significantly disturbing the soil of the roadbed slope on which the wing wall is attached, and is highly susceptible to slope instability, thereby threatening the track smoothness and traffic safety of adjacent lines. Furthermore, the new and old structures after demolition often only have a simple vertical interface with limited contact area, resulting in insufficient overall load-bearing capacity and long-term bonding reliability.

[0022] In this embodiment of the invention, a stable location is first selected on the road shoulder near the culvert extension site, a concrete foundation is poured, and an automatic monitoring device is installed. This device continuously monitors the vertical and horizontal displacement of the roadbed and track during construction, providing real-time data support for construction safety. Subsequently, according to the design drawings, a total station is used to accurately mark the stepped outline that needs to be removed and the width line of the vertical concrete filling at the bend on the surface of the existing wing wall and capstone. To ensure that the markings remain clear and durable in subsequent vibration and dusty environments, a hammer drill is used to drill holes at intervals along the marked path, embedding metal nails with reflective coating, and then elastic paint is used to connect the lines, forming a clear and solid construction benchmark.

[0023] To create a safe space for subsequent cutting operations, protective excavation is required at the location of the roadbed slope corresponding to the wing wall to be removed. The protection is achieved by driving in a double layer of steel rail piles 11, arranged parallel to the edge of the slope, and driven vertically into the soil to the predetermined depth using a vibratory hammer. The penetration rate is closely monitored during the driving process. If underground obstacles prevent the reaching of the designed depth, the process is immediately stopped, and grouting is performed in the adjacent holes for reinforcement (for example, steel plates can be pre-embedded in the grouting body, and the steel rail piles can be welded to the pre-embedded steel plates for fixation). After the steel rail piles are installed, they are horizontally connected at the top with wire ropes, and channel steel scissor braces 3 are welded between the piles to form a stable spatial support system. Under this protection, the earthwork is excavated in layers. After each layer is excavated, the displacement of the top of the rail pile is monitored. If the deformation exceeds the limit, it is stopped immediately, and a thin layer of concrete is quickly laid on the excavation surface to seal it. After it has a certain strength, the next layer of excavation is continued. In this way, the slope deformation is dynamically controlled until a working surface with a sufficient width and stability is formed outside the wing wall removal line.

[0024] Cutting is the core process. First, vertical cutting is performed along the marked bends and the vertically fitted width line. Before cutting, a guide hole penetrating the wall thickness is pre-drilled at the end of the marked line using a diamond thin-walled drill bit. The cutting wire of the wire saw is threaded through and tensioned to form a loop. After starting the equipment, the first cut is made along the marked line, with the depth controlled to about half the wall thickness, forming a guide groove. A second cut is then made along this groove until the wing wall and capstone are completely cut vertically through. This staged cutting method effectively ensures the accuracy of the cutting trajectory and obtains a smooth vertical cross-section. Simultaneously with vertical cutting, a circulating water cooling system with pressure regulation and atomizing nozzles is configured to spray cooling water containing fine stone powder onto the cutting area to suppress dust and reduce the heat impact of cutting. After all vertical cuts are completed, stepped horizontal cutting is performed. Horizontal cutting begins at the top of the wing wall and proceeds downwards layer by layer. Using a wire saw or stone cutting machine, the depth of each horizontal cut surface can be made consistent with the designed step height. During cutting, the guide rollers are kept close to the completed upper cut surface or the original wall surface to ensure the flatness and verticality of each cut surface.

[0025] After cutting, the resulting series of stepped horizontal surfaces undergo interface treatment. Using a pointed pneumatic pick at a certain angle, the stepped surfaces are roughened until the surface aggregate is exposed. Next, at regular intervals along the horizontal direction of the stepped surface, a regular groove running the width of the stepped surface is chiseled out using a flat-headed pneumatic pick. Then, the surface layer of the existing wing wall foundation at the corresponding locations of the bends and flared sections is removed to a certain depth to form anchorage areas. Afterwards, all loose particles and dust on the treated surfaces are thoroughly removed using a wire brush and high-pressure air, and the surfaces are then moistened with water.

[0026] Reinforcing steel installation and concrete pouring are carried out on a clean, moist surface. First, the prefabricated reinforcing steel frame for the heightened sidewall is hoisted into place, while simultaneously inserting one end of the L-shaped structural reinforcement for the vertical infill into the excavated foundation area. To enhance the mechanical connection between the new and old structures, holes are drilled on the existing wing wall step surface corresponding to the main reinforcement positions, and new main reinforcement is anchored to the old wall using rebar anchoring technology. Concrete pouring begins at the bottom of the excavated foundation area and proceeds continuously in layers. When pouring to the groove area, a vibratory tamping rod is used for focused compaction to ensure the concrete within the groove is densely packed. When the concrete reaches the step surface height, pouring is paused, and the concrete surface at the junction is roughened by patting and rubbing before continuing upwards to complete the heightened sidewall section. After all concrete is poured, it is promptly covered and kept moist for curing. Through these steps, a vertical infill and heightened sidewall are finally formed on the existing wing wall, tightly integrated with the original structure through the step surface, groove, and concrete anchored into the foundation, achieving a safe and stable extension.

[0027] Further, the second step of this invention specifically includes: using a total station to preliminarily mark the positions of the stepped chisel lines and the vertical filling lines at the bends on the existing wing wall and capstone surface according to the coordinates of the design drawings; after the lines are determined, using an electric hammer, holes with a depth of 15 mm to 20 mm are drilled every 500 mm to 1000 mm along the marked line path, and metal marker nails with reflective coatings are embedded in the holes; finally, elastic paint is used to snap or brush along the connecting lines of the metal marker nails to form a continuous visible marked line with a width of 5 mm to 8 mm.

[0028] This invention employs a composite marking method combining pre-embedded reflective metal markers with elastic coating, effectively overcoming the erosion and obscuring of marking lines caused by common environmental factors such as vibration, dust accumulation, and rainwater erosion. This ensures that the stepped chisel marks and vertical patching lines at bends remain clear and identifiable throughout the entire construction period. This durable and prominent marking provides a stable and reliable construction benchmark for subsequent precise vertical and horizontal cutting, guaranteeing the accuracy of the cutting position from the outset. It avoids cutting deviations or repeated measurements caused by a blurred benchmark, thus improving construction efficiency and project quality.

[0029] Further, the third step of this invention specifically includes: selecting P50 type steel rails as rail piles, and arranging two rows of rail piles at a center-to-center spacing of 1.5 meters to 2.0 meters in a direction parallel to the edge line of the existing roadbed slope to form a double-layer support; using a vibratory hammer to vertically drive the rail piles into the roadbed slope soil, controlling the driving depth of the rail piles between 3 meters and 5 meters; and immediately stopping the driving of the rail pile when the penetration rate of the vibratory hammer is less than 50 millimeters within 1 minute or when encountering a rigid obstacle. For rail piles that fail to reach the predetermined depth due to underground obstacles, a first pilot hole with a diameter of 100 mm to 150 mm should be drilled within a range of 0.75 m to 1.0 m on each of their adjacent sides using a small water drill or geological drilling rig. The depth of this first pilot hole should exceed the top of the obstacle by 0.5 m to 1.0 m. Then, M30 grade cement mortar should be injected into the first pilot hole. Once the grout strength reaches 10 MPa, the original rail pile should be fixed to the grout. After the rail piles are laid out, tensioners and wire ropes are used to laterally connect the tops of adjacent rail piles in the same row. Simultaneously, diagonal channel steel scissor bracing is welded between the two layers of rail piles to form a spatial truss-like combined support structure. After the protective structure is completed, the slope excavation is carried out in layers, with each layer being 0.8 to 1.2 meters thick, and the net distance between the excavated slope surface and the rail piles is maintained at 0.3 to 0.5 meters. During the excavation process, a total station is used to monitor the horizontal position of the rail pile tops in real time. If the cumulative horizontal displacement of the pile top caused by a single excavation layer exceeds 5 mm, the excavation should be immediately suspended, and a layer of C20 fine stone concrete with a thickness of not less than 50 mm should be laid on the excavation surface of that layer for temporary sealing. The next layer of excavation can only be carried out after the concrete strength reaches 70% of the design value. The final excavation surface 12 should be extended outward by 1.2 to 1.8 meters from the step-type chiseling line of the wing wall, and the slope surface of the excavated side should be manually trimmed to remove loose soil and rocks.

[0030] In the extension and reconstruction of existing culverts, cutting and removing existing wing walls typically requires excavation of the adjacent roadbed slope to create working space. Traditional slope excavation and support methods employ simple single-row rail pile protection. This existing method often lacks precise control measures when facing complex geological conditions such as karst development, the potential presence of underground boulders, or old foundations. If the rail piles encounter hard obstacles during driving, forced construction often results in pile damage and displacement, leading to inherent defects in the support system. Furthermore, the excavation process is often carried out in a single, or roughly layered manner, lacking real-time monitoring and dynamic feedback control of the support structure's deformation. The stress release caused by excavation can be rapidly transmitted, posing a potential threat to the stability of the adjacent railway roadbed, resulting in high construction safety risks.

[0031] In this embodiment of the invention, P50 type steel rails are first selected as the support piles. Two rows of rail piles are arranged parallel to the edge line of the roadbed slope, with a center-to-center spacing of approximately 1.8 meters, forming a double-layer support system. A vibratory hammer is used to drive the rail piles vertically into the soil, with a target depth set at approximately 4 meters. During the driving process, the operator closely observes the penetration rate of the vibratory hammer. If a pile's penetration depth is found to be less than 50 millimeters within one minute, or if the hammer head reports an abnormal impact, indicating that it may have encountered underground obstacles such as boulders, the driving operation for that pile is immediately stopped, and its actual penetration depth is recorded.

[0032] For rail piles that did not reach the predetermined depth due to obstacles, a backup reinforcement plan was immediately initiated. Within a range of approximately 0.9 meters on each side of the pile, a pilot hole with a diameter of approximately 120 mm was drilled using a small geological drilling rig. The drilling depth, based on geological survey data or the condition of the exposed obstacles, was to ensure it reached approximately 0.8 meters below the top of the obstacle. After drilling, M30 strength grade cement mortar was poured into the hole, ensuring a full and dense filling. Once the strength of the mortar test block cured under the same conditions on-site reached 10 MPa, the grouting body was considered to have a certain load-bearing and consolidation capacity. At this point, the previously unplaced rail pile was reliably connected and fixed to this grouting body, thereby forming an effective alternative bearing point in the local obstacle area.

[0033] After all rail piles were laid, overall connection and reinforcement were immediately carried out. Using tensioners and wire ropes, the pile heads of adjacent rail piles in the same row were tightened and laterally connected, forming a continuous lateral constraint. Next, between the front and rear rows of rail piles, multiple diagonal scissor braces were welded onto channel steel of appropriate specifications, connecting the front and rear rows of rail piles in space into a stable truss structure, greatly improving the rigidity and lateral displacement resistance of the overall support system.

[0034] After the protective structure passes inspection, layered excavation begins. Excavation is strictly carried out in layers and steps, with each layer's thickness controlled to approximately 1 meter. During excavation, machinery must be operated with extreme caution to ensure a clearance of approximately 0.4 meters between the temporary slope formed and the nearest rail pile, preventing collisions with the support piles or excessive excavation of the soil behind the piles. After each layer of earthwork is removed and before the next layer is excavated, surveyors must use a total station to comprehensively monitor the horizontal displacement of the tops of all rail piles. If monitoring data shows that a particular excavation step results in a cumulative horizontal displacement of the pile tops exceeding the warning value of 5 millimeters, subsequent excavation work must be immediately suspended.

[0035] During the pause, construction workers quickly implemented a temporary sealing treatment on the exposed excavation surface of this layer. A sealing layer of C20 fine aggregate concrete, at least 50 mm thick, was laid, covering the entire excavation section. This sealing layer rapidly inhibits stress release and soil deformation, acting as a temporary "stabilizing skin." Excavation of the next layer can only proceed after the concrete strength of the sealing layer has increased to more than 70% of its design strength and monitoring confirms that the displacement has stabilized. This process is repeated until the excavation depth meets the requirements. The final working space should extend approximately 1.5 meters outward from the marked stepped chisel lines on the wing wall to provide sufficient space for subsequent cutting equipment placement and personnel operations. After all excavation is completed, manual labor is required to finalize the slope surface, removing all loose soil and rocks to ensure a clean and safe working surface.

[0036] The invention further includes, in its fourth step, the following: When performing vertical cutting, firstly, at one end of the marked bend vertically, a second guide hole penetrating the thickness of the existing wing wall is drilled using a 50mm diameter diamond thin-wall drill bit; the cutting rope of the wire saw is passed through the second guide hole and tensioned to form a closed cutting loop; the wire saw is started to make the first cut along the marked line, with the depth of the first cut controlled to one-third to one-half of the wall thickness, forming a guide groove; after completing the first cut, the tension and cutting speed of the wire saw are adjusted, and a second cut is made along the same guide groove until the existing wing wall and capstone are completely cut through, forming a complete vertical cut surface; this process is repeated during both vertical and horizontal cutting. Throughout the process, a circulating water cooling system with a pressure regulating valve and atomizing nozzles is configured. The outlet of this system is aligned with the contact area between the cutting rope or cutting saw blade and the wall. The cooling water pressure is maintained between 0.2 MPa and 0.4 MPa. The water flow is mixed with fine stone powder with a particle size of less than 0.1 mm to enhance the cooling and lubrication effect and suppress dust. After all vertical cuts are completed, stepped horizontal cuts are performed. Horizontal cuts must start from the top of the wing wall and proceed layer by layer downwards. The depth of each horizontal cut can be the same as or greater than the corresponding step height. During cutting, ensure that the guide wheels of the cutting equipment are in close contact with the completed upper cut surface or the original wall surface to ensure the verticality and flatness of adjacent cut surfaces.

[0037] The atomizing nozzles of the circulating water cooling system are selected as high-pressure atomizing nozzles, which are characterized by: a coarse flow channel (2-3mm) that is compatible with fine stone powder circulating water; and a spray pressure of 0.2-0.8MPa, which can form "fine water mist" (droplet diameter 50-100μm), taking into account both cooling and dust suppression.

[0038] In the cutting of existing culvert wing walls, traditional methods often involve using a circular saw or a large cutting machine to cut directly along the marked line in one go. However, for older wing walls made of mortar-grouted rubble masonry that have been in use for many years and may have uneven material composition, this one-time cutting method is prone to deviation in the cutting trajectory due to unstable initial equipment path or differences in the strength of the stones inside the wall, resulting in uneven cut surfaces or even localized damage. At the same time, the large amount of heat generated by high-speed cutting may adversely affect the cutting equipment and the wall interface, and the accompanying dust also seriously pollutes the working environment, affecting operational accuracy and personnel health.

[0039] In this embodiment of the invention, the vertical cut at the bend is performed first. Based on the wall thickness, the operator carefully drills a second guide hole, penetrating the entire thickness of the wing wall, at one end of a pre-marked vertical filling line, using a diamond thin-walled drill bit with a diameter of approximately 50 mm. During drilling, the drill bit must be kept vertical to ensure the hole is straight. After drilling, the cutting rope of the wire saw is passed through the hole and properly connected to form a closed cutting loop. Simultaneously, the equipment is adjusted to precisely align the cutting rope with the marked line on the wall.

[0040] After the equipment is started, it does not immediately perform a full-thickness cut. Instead, it first cuts into the wall along the marked line with relatively gentle cutting parameters. The depth of the initial cut is controlled to about half the wall thickness. The purpose is not to cut through, but to "carve" a clear and accurate guide groove on the wall surface. This guide groove provides a physical path that is less prone to deviation for the subsequent final cut. After completing the guide groove, the operator adjusts the tension and cutting speed of the wire saw according to the wall material feedback, and then guides the cutting rope to make a second cut along the formed guide groove. This time, the cut will smoothly penetrate the remaining wall thickness until the wing wall and the capstone above it are completely cut off, ultimately resulting in a vertical cut surface with a high degree of conformity to the design line and a flat cross-section.

[0041] Throughout the entire cutting operation, whether it's vertical cutting or the subsequent horizontal cutting, a dedicated circulating water cooling system is required. This system is equipped with pressure regulating valves and atomizing nozzles, with the water outlet precisely aligned with the point of contact between the cutting rope or saw blade and the wall. The cooling water pressure is maintained within a moderate range, and extremely fine stone powder particles (such as fine stone powder with a particle size of less than 0.1 mm) are mixed into the water. This system serves multiple purposes: the continuous water flow effectively cools the high-speed friction of the cutting components, preventing overheating damage; the mixed fine stone powder enhances the coolant's lubrication and debris-carrying capacity; and, most importantly, the atomized water flow minimizes the spread of dust generated during cutting, keeping the work surface relatively clean and improving visibility and the working environment.

[0042] After completing all necessary vertical cuts, the next step is the stepped horizontal cutting stage. Horizontal cutting follows a top-to-bottom sequence, starting from the top of the wing wall and proceeding layer by layer downwards. During operation, it is crucial to ensure that the depth of each horizontal cut is completely consistent with the designed step height. To guarantee good vertical alignment and overall flatness of each cut surface, the guide wheels or guiding devices of the cutting equipment must always be in close contact with the completed upper-layer cut surface or the original wing wall surface as a reference, effectively preventing tilting or misalignment of the cut surface in the depth direction. Through the above-described method of staged cutting, pre-formed guidance, continuous cooling, and close contact with the reference, high-quality, high-precision cut surfaces can be obtained on old, heterogeneous masonry wing walls, laying a solid foundation for the reliable bonding of new and old concrete.

[0043] The present invention further includes the following steps for performing stepped horizontal cutting: Before starting each layer of horizontal cutting, a rebound hammer is used to test the strength of the existing wing wall below the proposed cutting path. At least three test areas are selected, and 16 points are tested in each test area. When the average rebound value of a certain test area is less than 20 or the dispersion is greater than 5, a row of threaded steel bars with a diameter of 12 mm and a length of 300 mm is pre-embedded as temporary reinforcing bars 100 mm to 150 mm below the horizontal cutting line of that layer. The embedding depth is 200 mm, and the exposed part is welded and poured with the reinforcing bars of the heightened side wall to be constructed later. When performing horizontal cutting, a layered, stepped retreat method is adopted. After each step is completed... After horizontal cutting, immediately use a crack monitoring instrument to scan the surface of the horizontal cut surface and the adjacent existing wall to record the width and length of any new or extended cracks. If a crack width exceeds 0.3 mm and a length exceeds 200 mm, drill a stress relief hole with a diameter of 30 mm at the end of the crack, with the hole depth exceeding the crack tip by 50 mm, and inject epoxy resin grout into the hole. Use a special grouting device to slowly inject the grout from the preset grouting hole at low pressure until the grout seeps out from the crack surface. After all stepped horizontal cuts are completed, use a high-pressure water gun to clean all cut surfaces with a water pressure of not less than 8 MPa to remove the mud, powder, and loose fine particles adhering to the surface.

[0044] In the stepped cutting construction of existing masonry rubble masonry wing walls, traditional multi-level horizontal cutting operations often lack a systematic assessment and process control of the current condition of the existing wall. Construction usually involves cutting layer by layer according to a predetermined elevation line, making it difficult to predict and address potential strength degradation, internal loosening, or hidden cracks that may exist in the wall due to its age. Cutting vibrations may induce or amplify these hidden defects, affecting the structural integrity of the remaining wall. In addition, the mud and powder generated during cutting easily adhere to the cut surface, and if not thoroughly cleaned, it will seriously affect the bonding performance between the old and new concrete.

[0045] In this embodiment of the invention, the operator uses a rebound hammer to select at least three representative areas on the wall below the horizontal line to be cut as test zones. Sixteen points are tested in each test zone, and the rebound values ​​are recorded, along with their average and dispersion. If the average rebound value of a test zone is found to be below 20, or the data dispersion at each test point is too large, it indicates that the wall strength in that area may be insufficient or the material may be highly heterogeneous. Therefore, before the formal cutting, a row of 12mm diameter threaded steel bars is pre-inserted as temporary reinforcement approximately 12cm below the cutting line. Holes are drilled using a hammer drill to ensure an insertion depth of 20cm and that the exposed length of the steel bars is appropriate so that they can be connected to the steel reinforcement framework of the raised side wall later. This pre-reinforcement measure provides additional support to weak areas, compensating for potential load-bearing capacity losses due to material aging.

[0046] When performing the stepped horizontal cutting, a layered, step-by-step retreating operation sequence is adopted. Specifically, first, at the first elevation at the top of the wing wall, a full-length horizontal cut is completed along its entire length, forming a complete horizontal cross-section. After all the cutting of this layer is completed and the necessary inspections are performed, the equipment is lowered to the next elevation to perform the second full-length horizontal cut, and so on, advancing layer by layer downwards. This method of "completing all cuts at the same elevation first, and then descending to the next elevation" decomposes the complex three-dimensional cutting into multiple relatively simple planar cuts, which is beneficial for centralized control of the quality and accuracy of each layer of cutting.

[0047] After each horizontal cut is completed to the height of a step, work does not immediately move to the next level. Construction workers must immediately use a crack inspection instrument to meticulously scan the newly formed horizontal cut surface and the adjacent existing wall sections. The purpose is to promptly detect any new micro-cracks induced by the cutting work, or to observe whether existing cracks show signs of expansion. Once the scan reveals a crack exceeding 20 cm in length and 0.3 mm in width, it is considered a structural crack requiring treatment. Treatment involves first drilling a stress relief hole approximately 30 mm in diameter at the end of the crack, with the hole extending at least 5 cm beyond the crack tip to block its further extension. Then, epoxy resin grout is injected under pressure into the hole. The grout penetrates and fills the crack, and after curing, the cracked portion can be re-bonded, restoring the integrity of the area.

[0048] After all the stepped horizontal cutting work is completed, before proceeding to the roughening process, all newly created cut surfaces must be thoroughly cleaned. Using a high-pressure water gun, at a water pressure of at least 8 MPa, the cut surfaces are rinsed at close range. The high-pressure water flow effectively strips and washes away the mud adhering to the wall surface, cutting dust, and all loose fine particles. This process ultimately exposes a solid, clean wall aggregate base, creating optimal interface conditions for subsequent roughening, grooving, and the tight bonding of new and old concrete.

[0049] Furthermore, in the present invention, the method of using a layered step-back approach during horizontal cutting is as follows: at the same elevation, a full-length horizontal cut is first completed along the length of the wing wall to form a horizontal cross-section, and then the next layer of horizontal cutting is performed at the next step height, with the vertical distance between two adjacent horizontal cutting surfaces being the step height.

[0050] This invention simplifies complex multi-level stepped 3D cutting into a series of clear 2D planar cutting tasks. This sequential arrangement allows for concentrated cutting operations at each level, eliminating the need for operators to frequently switch equipment and adjust their posture between different elevations, thus improving focus and operational efficiency. More importantly, it provides clear process nodes for real-time quality inspection, crack scanning, and necessary reinforcement or repair of each cut surface, ensuring that the next layer is only started after the previous layer has been completely processed. This effectively avoids the accumulation of quality problems and safety hazards caused by simultaneous construction of multiple layers or chaotic sequences, ultimately guaranteeing the overall accuracy and structural safety of the entire stepped cutting system.

[0051] Further, the fifth step of this invention specifically includes: using a pointed pneumatic pick to roughen all the stepped surfaces formed by cutting, with the impact direction of the pneumatic pick at an angle of 45 to 60 degrees to the stepped surface, and the roughening depth being sufficient to expose the surface aggregate; using a flat-headed pneumatic pick to chisel a transverse groove every 100 millimeters along the stepped surface, the groove being 10 millimeters deep and 35 millimeters wide, with the length of the groove extending through the entire width of the stepped surface; after completing the stepped surface treatment and cleaning up the debris, using a pneumatic pick to remove 200 millimeters of the existing wing wall foundation at the corresponding positions of the bend and flared sections, removing the boundaries. The surface should be neat and tidy. Before installing the reinforcing bars, use a wire brush to remove all loose particles and dust from the roughened step surface, grooves, and the area where the wing wall foundation has been removed. Then, use a high-pressure air blower to clean the surface. When installing the reinforcing bars, first hoist the prefabricated skeleton of the vertical main bars and horizontal distribution bars of the raised side wall into place as a whole. Then, insert one end of the L-shaped structural bar used for pouring the vertical inlay into the area where the wing wall foundation has been removed, and tie the other end to the reinforcing bar skeleton of the raised side wall. Before pouring concrete, spray water on the cleaned step surface, grooves, and the area where the foundation has been removed to fully moisten the surface but without standing water.

[0052] In the renovation of existing masonry wing walls, traditional interface treatment methods are often rather crude. The surface of the old wall may only be roughened with ordinary tools, the size and spacing of the grooves are arbitrary, and cleaning is often inadequate, resulting in a dust and loose particle isolation layer at the interface between the old and new concrete. During reinforcement installation, the connection between the new reinforcement cage and the old wall may be simplistic, lacking effective mechanical anchoring. These practices make the interface a weak point, affecting the integrity of the composite structure and the reliability of load transfer.

[0053] In this embodiment of the invention, firstly, the operator holds a pointed pneumatic pick and adjusts its impact direction to an angle of approximately fifty degrees with the step surface. This angled impact is used to systematically roughen the step surface. The roughening operation aims to remove the surface cement mortar plaster, exposing the internal aggregate stones, creating a uniformly rough surface. Next, a flat-headed pneumatic pick is used to chisel a groove horizontally along each step surface, strictly adhering to a spacing of ten centimeters. The depth of this groove is controlled to be ten millimeters, the width thirty-five millimeters, and its length must extend across the entire width of the step surface, thus forming a series of regular horizontal keyways on each step.

[0054] After roughening and grooving all the stepped surfaces, the foundation of the wing wall needs to be treated. Using a pneumatic hammer, the surface layer of the existing wing wall foundation at the corresponding locations of the bends and flared sections is removed to a depth of 20 centimeters. The removal work must be carefully controlled to keep the boundaries of the removed area as neat as possible, creating a regular formwork space for subsequent pouring. After the physical treatment of the interface is completed, cleaning becomes a crucial step. Construction workers use wire brushes to vigorously scrub all roughened stepped surfaces, the inside of each groove, and the foundation removal area to remove all loose particles and adhering powder generated by the chisel work. Subsequently, high-pressure air equipment is used to thoroughly blow away all treated surfaces, removing any remaining fine dust and ensuring that the bonding interface is structurally clean.

[0055] Reinforcing steel installation is carried out on a clean interface. First, the prefabricated and tied reinforcing steel frame for the raised side wall is hoisted to the designed position and temporarily stabilized. Then, the pre-bent L-shaped structural bars are taken out, one end is inserted into the wing wall foundation area that has been chiseled to a depth of 20 cm, and the other end is firmly tied and fixed to the positioned reinforcing steel frame for the raised side wall, thus connecting the old and new vertical and horizontal structural components. After all the reinforcing steel installation work is completed and before concrete pouring begins, a final interface treatment is required. Using a spray bottle or sprinkler, clean water is sprayed onto all roughened step surfaces, the inside of grooves, and the foundation chiseling areas to fully moisten these old base surfaces. The amount of water sprayed must be controlled, with the goal of achieving a saturated surface dry state, i.e., the surface is wet but without standing water. This process reduces the rapid absorption of water from the old base surface into the newly poured concrete, which is beneficial to the hydration of cement paste and the formation of cement stone at the interface, promoting bonding from a material chemical perspective. Through the meticulous and interconnected processes described above, a solid foundation was laid for the subsequent concrete pouring and the firm integration of the old and new structures.

[0056] Furthermore, the reinforcement installation of the present invention includes: before the reinforcement cage of the heightened side wall is in place, drilling holes with a diameter 4 mm to 6 mm larger than the diameter of the main reinforcement at the design position of the vertical main reinforcement on the stepped surface of the existing wing wall using an electric hammer, with a hole depth of 150 mm; injecting epoxy resin adhesive into the hole, and then inserting the end of the vertical main reinforcement of the heightened side wall into the hole, ensuring an insertion depth of not less than 120 mm; after the epoxy resin has cured, binding and fixing the remaining part of the reinforcement cage of the heightened side wall; for the L-shaped structural reinforcement installed in the area where the foundation of the wing wall is removed, welding a short horizontal steel bar with a length of not less than 200 mm to the outside of the corner between its vertical and horizontal sections, and welding the short steel bar to the L-shaped structural reinforcement to form a triangular support.

[0057] In the traditional steel reinforcement installation process for extending and renovating the wing walls of existing culverts, current technology typically connects the newly fabricated steel reinforcement cage to the old wall through simple binding or bonding with subsequently poured concrete. For L-shaped steel bars inserted into the old foundation area, the anchorage force mainly relies on their straight section length. This method primarily provides friction and limited bond strength at the interface between the new and old concrete, exhibiting weak resistance to horizontal shear forces and vertical pull-out forces. Under long-term loads or repeated stress, it may become a weak link in force transmission, affecting the overall performance and safety reserve of the composite structure.

[0058] In this embodiment of the invention, before the final binding and fixing of the overall steel reinforcement framework of the heightened side wall, key vertical anchoring points must first be established on the stepped surface of the existing wing wall. According to the design drawings, the operators accurately mark the corresponding position of each vertical main reinforcement bar on the roughened stepped surface. Then, using an electric hammer, vertical holes with a depth of 15 cm are drilled at the marked points, with a hole diameter approximately 5 mm larger than the diameter of the main reinforcement bar to ensure sufficient gaps for adhesive filling. After drilling, a sufficient amount of epoxy resin adhesive is injected into the holes using a special syringe. Then, the ends of the vertical main reinforcement bars of the heightened side wall are quickly inserted vertically into the holes, ensuring an insertion depth of not less than 12 cm, and adjusted to the designed angle. After insertion, static curing is required until the epoxy resin is completely cured and reaches its designed bonding strength. This step, through chemical bonding and mechanical locking, directly anchors the roots of the new reinforcement bars to the interior of the old wall, achieving a rigid connection between the old and new structures at the reinforcement level.

[0059] Subsequently, the remaining transverse reinforcing bars of the heightened sidewall are tied to the existing main reinforcing bars to form a complete skeleton. For the L-shaped structural bars already inserted into the excavated area of ​​the wing wall foundation, in order to further improve their anchorage reliability and pull-out and shear resistance in the concrete, local reinforcement is required at their key stress points. Specifically, a short horizontal steel bar with a length of not less than 20 cm is taken and attached tightly to the outside of the corner of the vertical and horizontal sections of the L-shaped structural bar. Then, by welding, the two ends of this short horizontal steel bar are firmly welded to the vertical and horizontal sections of the L-shaped structural bar, respectively, thus forming a rigid triangular support structure on the outside of the corner. This additional triangular support essentially increases the effective anchorage size and complexity of the L-shaped bars in the foundation concrete, changes the force transmission path, and enables it to more effectively distribute and transmit the tensile and shear forces from the superstructure to the foundation concrete, significantly improving the bearing capacity and reliability of the joint area. Through the above-mentioned composite measures of rebar anchorage and structural bar welding reinforcement, a strong internal skeleton connection is provided for the entire new and old concrete composite structure.

[0060] Further, the concrete pouring of this invention specifically includes: the concrete pouring begins from the bottom of the area to be removed from the wing wall foundation, using a layered continuous pouring method, with each layer not exceeding 500 mm in thickness; when the concrete reaches the lower edge of the transverse groove, a 30 mm diameter immersion vibrator is used to focus on vibrating the area inside the groove, the vibrator should be inserted into the bottom of the groove and slowly withdrawn to ensure that the groove is completely and densely filled with concrete; when the concrete reaches the height of the step surface, pouring is temporarily stopped, and the concrete surface at the junction of the step surface is roughened with a wooden trowel, and then the concrete for the raised side wall portion continues to be poured upwards; after all the concrete is poured, a permeable geotextile is covered on the top surface of the raised side wall, and drip irrigation is used to keep the geotextile continuously moist, with a curing time of not less than 7 days.

[0061] In the concrete pouring process for extending and renovating the wing walls of existing culverts, traditional construction methods often fail to adequately address the complex, patched areas. During pouring, the conventional method of proceeding from one end to the other may be used, easily overlooking or insufficiently compacting details such as transverse grooves and corners, leading to insufficient concrete density and hidden voids. At the junction of old and new concrete, such as steps, the treatment is often rough due to limited operating space or insufficient attention. During the curing stage, simple methods like sprinkling water or covering with plastic film are often used, resulting in uneven and unsustainable moisture supply, potentially affecting the normal development of concrete strength, especially the surface layer.

[0062] In this embodiment of the invention, commercially available concrete meeting design requirements is transported to the site, and its slump and other workability properties are checked first. The pouring starting point is selected at the bottom of the excavated wing wall foundation area, and filling begins from this point upwards and horizontally. A layered continuous pouring process is adopted, strictly controlling the thickness of each layer of concrete to ensure it does not exceed fifty centimeters. After each layer is poured, a 30-millimeter diameter immersion vibrator is immediately used for compaction. The vibrator must be inserted vertically with quick insertion and slow withdrawal, evenly distributed, to ensure the concrete achieves sufficient density.

[0063] Special attention is required when the poured concrete surface rises to near the pre-designed transverse groove on the step surface. As the concrete covers the lower edge of the groove and begins to fill the space, the operator must carefully insert the vibrator, aligning it precisely with the groove. The vibrator should be inserted to the bottom of the groove and moved slowly within it. Through the force of the vibrator and the fluidity of the concrete, ensure that this narrow and crucial "keyway" space is completely filled with concrete, leaving no air bubbles or voids.

[0064] When the concrete is poured to the height of the existing wing wall step, the pouring operation is paused. At this time, the construction workers use a wooden trowel to carefully pat and roughen the surface of the newly poured concrete at the junction of the steps. The purpose of this operation is to eliminate any minor defects that may be caused by formwork joints or water seepage in this area, forming a rough but solid transition surface. This not only contributes to a smooth appearance but also enhances the interlocking and bonding between the new and old concrete at the interface.

[0065] After the entire raised sidewall section is poured, curing should begin immediately. A permeable geotextile should be laid flat and tightly over the concrete surface. A drip irrigation system should be used for curing, with drip pipes evenly distributed on the geotextile. By adjusting the drip rate, the geotextile should be kept consistently moist without excess water running down. This curing method provides a continuous and uniform humidity environment for the concrete's strength development. The curing period should be no less than seven days to ensure the concrete performance meets design requirements.

[0066] Further, the first step of this invention specifically includes: the automatic monitoring equipment monitors the vertical displacement of the track, the horizontal displacement of the track, the vertical displacement of the roadbed, and the horizontal displacement of the roadbed; the automatic monitoring equipment is fixed by a concrete base poured on the shoulder, the depth of which is not less than 500 mm; the automatic monitoring equipment integrates a solar panel and a battery for continuous power supply in the absence of an external power source; the automatic monitoring equipment also integrates a wireless communication module for transmitting displacement data to a remote server via a mobile network; after the automatic monitoring equipment is installed, a total station is used to perform joint measurements on the monitoring reference points during railway operation intervals to calibrate the initial readings of the automatic monitoring equipment.

[0067] In construction alongside railway lines, traditional monitoring of subgrade and track displacement relies heavily on manually operated total stations or levels, with intermittent measurements taken within limited railway "maintenance windows." This method suffers from low data acquisition frequency, difficulty in capturing continuous deformation trends during construction, and significant susceptibility to weather, lighting conditions, and the experience of surveyors, resulting in insufficient data reliability and timeliness. Furthermore, the installation of monitoring equipment is often temporary, making it susceptible to displacement due to train vibrations or weather conditions, leading to unstable monitoring benchmarks and an inability to accurately reflect minute displacements.

[0068] In this embodiment of the invention, to ensure the safety and controllability of the entire construction process, the first step is to establish an automated and highly reliable monitoring system. Near the culvert extension site, a location is selected on the road shoulder away from the slope and with a solid foundation. A pit at least 50 centimeters deep is manually excavated, and concrete is poured on-site to form a stable base. After the base reaches the required strength, the automatic monitoring equipment is securely installed on it. This equipment integrates multiple high-precision sensors, enabling simultaneous and continuous monitoring of several key indicators, including the vertical and horizontal displacement of the railway track, as well as the vertical settlement and horizontal lateral displacement of the roadbed itself.

[0069] To enable long-term, unattended continuous monitoring, the equipment integrates energy and communication systems. A solar panel is mounted on top, which, together with a built-in battery pack, allows for energy self-sufficiency in environments without mains power, ensuring uninterrupted monitoring due to power outages. Simultaneously, the built-in wireless communication module transmits collected displacement data in real-time to a remote server or monitoring center via mobile networks. This allows technicians to monitor structural deformation dynamics in the construction area without being physically present, providing data support for timely engineering decisions.

[0070] After the equipment is installed and powered on, its initial readings require precise calibration. This work must be carried out during breaks in railway traffic, in a relatively stable environment. Surveyors use a high-precision total station to connect and measure stable benchmarks established outside the construction impact zone, while simultaneously recording the readings of the automatic monitoring equipment at that moment. Through comparison and calculation, the initial coordinates or displacement values ​​of the automatic monitoring equipment are systematically calibrated and corrected, thereby eliminating errors that may have been introduced during installation and ensuring the accuracy and reliability of the origin of all subsequent monitoring data. The establishment of this system provides a pair of real-time, alerting "eyes" for subsequent excavation, cutting, and pouring operations, laying the foundation for safe construction.

[0071] Furthermore, after forming the vertical insert and the heightened sidewall, the present invention also includes the step of completing the extension construction: constructing a cover plate 8 on the top of the heightened sidewall; constructing a new extension section wing wall 9 and foundation in the direction of the existing culvert outside the route; and finally carrying out the waterproof layer construction and backfilling of the culvert back of the entire extension culvert.

[0072] In this embodiment of the invention, the first step is to construct the cover plate at the top of the heightened sidewall. To minimize disruption to railway operations and maximize efficiency, a prefabrication and hoisting method is typically employed. Based on the design dimensions, reinforced concrete trapezoidal cover plates are prefabricated off-site. Once the cover plates meet the required strength, they are then smoothly hoisted to the designed position at the top of the heightened sidewall using a truck crane within the timeframe approved by the railway, ensuring a secure installation and smooth joints. If site conditions are special, a lightweight scaffold can be erected on top of the wall for in-situ casting, but meticulous construction organization is essential.

[0073] Next, on the outer side of the existing culvert, in the direction where the line needs to be extended, the construction of the new extended wing wall and its foundation will commence. Based on the design drawings, the excavation lines for the new wing wall foundation will be laid out. Using a combination of small excavators and manual labor, the foundation pit will be excavated in layers and sections to the design elevation. During excavation, care must be taken to protect the completed raised wing wall structure and the backfill soil behind it to avoid mechanical collisions and over-excavation. After the foundation pit passes inspection, the foundation reinforcement will be tied, formwork will be erected, and concrete will be poured. Once the foundation concrete reaches a certain strength, the construction of the new wing wall will be completed using the same formwork and cast-in-place method, ensuring that the settlement joint between the old and new wing walls is correctly positioned and vertically continuous.

[0074] After the main structure is completed, the waterproofing layer of the extended culvert will be constructed. Remove laitance and dust from the top surface and outer walls of the culvert, and continuously and evenly apply or lay waterproofing material on the cleaned surface. Special attention should be paid to reinforcing the waterproofing at the junction of new and old concrete, settlement joints, and other detailed nodes to ensure that the entire extended culvert forms a complete waterproofing system.

[0075] After the waterproofing layer passes inspection, the final backfilling is carried out. The backfill material used is the one specified in the design, and it is filled symmetrically in layers on both sides of the culvert. The loose thickness of each layer does not exceed the specification requirements. Small compaction machinery is used for careful compaction, and compaction tests are conducted as required to ensure backfill quality. During the backfilling process, close attention should be paid to protecting the existing roadbed slope and the newly constructed wing wall structure to avoid eccentric pressure. Once the backfill reaches the design elevation, the construction of the entire extended culvert is completed, forming an expansion facility that is reliably connected to the existing structure and has good overall performance.

[0076] Example 1 In the construction of a second track on a busy railway trunk line, it was necessary to extend and renovate an existing masonry slab culvert on one side. This culvert is located in a moderately developed karst area with complex underground conditions and is adjacent to the railway subgrade slope. The traditional method of completely demolishing the wing wall foundation for extension was rejected due to significant disturbance to the subgrade slope, high safety risks, and long required track travel time. Therefore, the step-by-step removal and patching method for extending the railway culvert wing wall, as described in this invention, was adopted.

[0077] The specific application methods are as follows: First, at a stable location on the road shoulder near the culvert extension point, a concrete base with a depth of over 500 mm was poured, and an automated monitoring device integrating solar power supply and wireless transmission was installed to monitor the vertical and horizontal displacement of the roadbed and track 24 hours a day. The initial data was calibrated through benchmark point connection.

[0078] Secondly, using a total station, stepped chiseling lines and vertical filling lines at bends were laid out at the designed locations. Then, using an electric hammer to drill holes and embed reflective metal nails, and then applying elastic paint, a durable and clear composite marking line was formed.

[0079] Subsequently, two rows of P50 steel rail piles were driven in parallel to form a double-layer support, outside the roadbed slope corresponding to the wing wall to be removed. The penetration rate was closely monitored during pile driving, and the process was immediately stopped when encountering underground boulders. M30 cement mortar was then injected into the adjacent holes for local reinforcement. The piles were tensioned with wire ropes and welded with channel steel scissor braces to form a spatial truss system. Under this protection, layered excavation was carried out. The displacement of the pile top was monitored after each layer was excavated. If the deformation of a single layer exceeded 5 mm, the excavation was immediately stopped, and a thin layer of C20 fine aggregate concrete was laid for temporary sealing. Excavation continued only after the concrete had gained sufficient strength, until a stable working surface extending 1.5 meters beyond the wing wall removal line was formed.

[0080] Next, the cutting operation begins. Guide holes are pre-drilled along the vertical width-filling line at the bend, and a wire saw is used to make two progressive cuts to create a smooth vertical cross-section. Throughout the cutting process, atomized water containing fine stone powder is used for cooling and dust suppression. Then, stepped horizontal cutting is performed from top to bottom. Before each layer of horizontal cutting, a rebound hammer is used to test the strength of the wall below, and temporary reinforcing ribs are pre-implanted in weak areas. The cutting adopts a "layered, stepped retreat" method, that is, a full-length cut is completed at the same elevation before descending to the next step. After each layer is cut, a crack observation instrument is immediately used to scan for cracks exceeding 0.3 mm in width and 200 mm in length. Stress relief holes are drilled at the ends of these cracks, and epoxy resin grout is injected to seal them. After all cutting is completed, the cut surfaces are thoroughly cleaned with a high-pressure water gun with a pressure of at least 8 MPa.

[0081] Next, the stepped surface formed by the cutting is finely processed. Using a pointed pneumatic pick at approximately a 55-degree angle, the surface is roughened until the aggregate is exposed. Then, using a flat-headed pneumatic pick, through grooves 10 mm deep and 35 mm wide are chiseled every 100 mm. Simultaneously, the foundation of the wing wall at the corresponding locations of the bends and flared sections is removed to a depth of 200 mm. After processing, the surface is thoroughly cleaned with a wire brush and high-pressure air, and then moistened with water.

[0082] Reinforcing steel installation is carried out based on the interface treatment. First, holes are drilled on the existing wing wall step surface, and epoxy resin anchoring technology is used to anchor the vertical main reinforcement of the heightened side wall into the old wall. Then, the prefabricated reinforcement skeleton of the heightened side wall is hoisted into place, and L-shaped structural bars are inserted into the excavated foundation area. Horizontal short steel bars are welded to the outside of the corners to form triangular supports, and then the overall skeleton is tied and fixed.

[0083] Finally, concrete pouring is carried out. Pouring begins from the bottom of the foundation removal area, with each layer not exceeding 500 mm in thickness. When pouring to the groove area, intensive vibration is applied to ensure dense filling; when pouring to the step height, pouring is paused, and the concrete surface at the junction is roughened by patting and troweling, then the pouring of the heightened sidewall continues. After pouring, permeable geotextile is covered and drip irrigation is used to maintain moisture for at least 7 days.

[0084] After the heightened sidewalls reached the designed strength, the subsequent steps included hoisting and installing the precast cover plates, constructing the new extended section wing walls and foundations, constructing the overall waterproof layer of the extended culvert, and symmetrically backfilling and compacting the back of the culvert, ultimately achieving the extension of the culvert.

[0085] This invention preserves most of the original wing wall structure through stepped cutting and employs dynamically monitored micro-disturbance support excavation technology, significantly reducing disturbance to the existing railway line slope and ensuring the immediate safety of the operating line, achieving "no slow-moving" or "minimal slow-moving" construction. The combined design of the stepped surface, transverse grooves, and anchored foundations greatly increases the contact area and shear resistance of the new and old materials. Combined with the regular base surface formed by precise cutting, thorough interface cleaning, mechanical connection of rebar, and targeted concrete pouring and curing processes, it ensures that the new and old concrete form a solid whole with excellent load-bearing performance. For underground obstacles in karst development areas, a flexible solution of intelligent obstacle-detection and local grouting reinforcement is adopted; to address the problem of uneven strength of old masonry rubble masonry, proactive control measures are introduced, including strength testing and pre-reinforcement before cutting, and immediate crack scanning and repair after cutting, effectively ensuring the safety of the construction process and the remaining structure. From precise layout based on composite markings to controlled cutting with cooling and dust suppression, to dynamic excavation and support based on real-time monitoring information, and automated displacement monitoring throughout the process, a comprehensive construction control system with interlocking steps and timely information feedback has been formed, improving project quality and construction safety. The method of this invention organically combines wing wall heightening with subsequent extension construction, with clear steps and smooth process connections, significantly improving construction efficiency and enhancing the structural robustness of the heightened and extended sections. It provides a replicable, efficient, and reliable technical solution for the renovation of existing railway culverts in similar complex environments.

[0086] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Further modifications can be readily implemented by those skilled in the art.

Claims

1. A method for constructing a stepped excavation, patching, heightening, and extension of a railway culvert wing wall, characterized in that, Includes the following steps: The first step is to install automatic monitoring equipment at a secure location on the road shoulder near the culvert extension site to monitor the displacement of the roadbed and track during construction. The second step is to measure and mark the stepped chisel lines and the vertical filling lines at the bends on the existing wing walls according to the design drawings. The third step is to drive steel rail piles into the roadbed slope excavation location where the existing wing wall needs to be removed for protection, and then carry out slope excavation to create working space for cutting and pouring. The fourth step is to use a wire saw to vertically cut the existing wing wall and capstone along the marked corner vertically; then, along the marked stepped chisel lines, use a wire saw to horizontally cut the existing wing wall in a stepped manner. The fifth step involves roughening the cut step surface and chiseling out a groove 10-20 mm deep and 30-40 mm wide at 100 mm intervals; then chiseling away 200 mm deep from the existing wing wall foundation at the corresponding positions of the bend and flared sections; then installing reinforcing bars on the treated step surface, grooves, and chiseled areas of the wing wall foundation, and anchoring the reinforcing bars to the existing wing wall; finally, pouring concrete to form a vertical insert and heightened side wall that is integrated with the existing wing wall.

2. The construction method for step-type removal, patching, heightening, and extension of railway culvert wing walls according to claim 1, characterized in that, The second step specifically includes: using a total station to preliminarily mark the positions of the stepped chisel lines and the vertical filling lines at the bends on the existing wing wall and capstone surface according to the coordinates of the design drawings; after the lines are determined, use an electric hammer to drill holes with a depth of 15 mm to 20 mm every 500 mm to 1000 mm along the marked line path, and embed metal marker nails with reflective coatings in the holes; finally, use elastic paint to draw or brush along the connecting lines of the metal marker nails to form a continuous visible marked line with a width of 5 mm to 8 mm.

3. The construction method for step-type removal, patching, heightening, and extension of railway culvert wing walls according to claim 1, characterized in that, The third step specifically includes: arranging two rows of rail piles at a center-to-center spacing of 1.5 to 2.0 meters in a direction parallel to the edge line of the existing roadbed slope to form a double-layer support; using a vibratory hammer to vertically drive the rail piles into the roadbed slope soil, controlling the driving depth between 3 and 5 meters; immediately stopping the driving of the rail pile when the penetration rate of the vibratory hammer is less than 50 mm within 1 minute or when encountering a rigid obstacle; drilling a first guide hole with a diameter of 100 to 150 mm within 0.75 to 1.0 meters on each side of the first guide hole, with a depth exceeding the top of the obstacle by 0.5 to 1.0 meters; then injecting M30 cement mortar into the first guide hole; after the grout strength reaches 10 MPa, fixing the original rail pile to the grout; after completing the rail pile layout... The tops of adjacent rail piles in the same row are horizontally connected, and diagonal channel steel scissor bracing is welded between the two layers of rail piles to form a spatial truss-type joint support structure. After the protective structure is completed, the slope earthwork is excavated in layers, with each layer having a thickness of 0.8 to 1.2 meters. The net distance between the excavated slope surface and the rail piles is maintained at 0.3 to 0.5 meters. During the excavation process, a total station is used to monitor the horizontal displacement of the top of the rail piles in real time. When the cumulative horizontal displacement of the pile top caused by a single excavation layer exceeds 5 millimeters, the excavation is immediately suspended, and a layer of C20 fine stone concrete with a thickness of not less than 50 millimeters is laid on the excavation surface of that layer for temporary sealing. The next layer of excavation is carried out after the concrete strength reaches 70% of the design value. The final excavation surface should extend outward by 1.2 to 1.8 meters beyond the stepped chiseling line of the wing wall.

4. The construction method for step-type removal, patching, heightening, and extension of railway culvert wing walls according to claim 1, characterized in that, The fourth step specifically includes: when making vertical cuts, firstly, at one end of the vertically inserted width line at the marked bend, drill a second guide hole penetrating the thickness of the existing wing wall; pass the cutting rope of the wire saw through the second guide hole and tension it to form a closed cutting loop; start the wire saw to make the first cut along the marked line, controlling the depth of the first cut to one-third to one-half of the wall thickness, forming a guide groove; after completing the first cut, adjust the tension and cutting speed of the wire saw and make a second cut along the same guide groove until the existing wing wall and capstone are completely cut through. This process creates a complete vertical cut surface. Throughout the vertical and horizontal cutting process, a circulating water cooling system with a pressure regulating valve and atomizing nozzles is configured. The outlet of this system is aligned with the contact point between the cutting rope or cutting saw blade and the wall. The cooling water pressure is maintained between 0.2 MPa and 0.4 MPa, and the water flow contains fine stone powder with a particle size of less than 0.1 mm. After all vertical cuts are completed, stepped horizontal cuts are performed. Horizontal cuts must start from the top of the wing wall and proceed layer by layer downwards. During cutting, ensure that the guide wheels of the cutting equipment are in close contact with the completed upper cut surface or the original wall surface.

5. The construction method for step-type chiseling, patching, heightening, and extension of railway culvert wing walls according to claim 4, characterized in that, The stepped horizontal cutting also includes the following steps: Before starting each layer of horizontal cutting, a rebound hammer is used to test the strength of the existing wing wall below the proposed cutting path. At least three test areas are selected, and 16 points are tested in each test area. When the average rebound value of a certain test area is less than 20 or the dispersion is greater than 5, a row of threaded steel bars with a diameter of 12 mm and a length of 300 mm is pre-embedded as temporary reinforcement at a depth of 200 mm below the horizontal cutting line of that layer. The exposed part is welded and poured with the reinforcement of the heightened side wall in subsequent construction. When performing horizontal cutting, a stepped retreat method is adopted. The process is as follows: After each step-height horizontal cut is completed, a crack monitoring instrument is immediately used to scan the surface of the horizontal cut surface and the adjacent existing wall to record the width and length of any new or extended cracks. If a crack is found to be wider than 0.3 mm and longer than 200 mm, a stress relief hole with a diameter of 30 mm is drilled at the end of the crack, with a depth exceeding 50 mm from the crack tip, and epoxy resin grout is injected into the hole. After all step-type horizontal cuts are completed, all cut surfaces are cleaned with a high-pressure water gun at a pressure of not less than 8 MPa to remove the mud, powder, and loose fine particles adhering to the surface.

6. The construction method for stepped removal, patching, heightening, and extension of railway culvert wing walls according to claim 5, characterized in that, When making horizontal cuts, a layered, stepped retreat method is adopted. Specifically, at the same elevation, a continuous horizontal cut is first made along the length of the wing wall to form a horizontal cross-section. Then, the next layer of horizontal cuts is made at the next step height. The vertical distance between two adjacent horizontal cut surfaces is the step height.

7. The construction method for stepped removal, patching, heightening, and extension of railway culvert wing walls according to claim 1, characterized in that, The fifth step specifically includes: roughening all the stepped surfaces formed by cutting, with the impact direction at an angle of 45 to 60 degrees to the stepped surface, and the roughening depth being sufficient to expose the surface aggregate; along the stepped surface, chiseling a horizontal groove every 100 mm, with a depth of 10 mm, a width of 35 mm, and a length extending through the width of the entire stepped surface; after completing the stepped surface treatment and cleaning up debris, chiseling away 200 mm deep from the existing wing wall foundation at the corresponding positions of the bend and flared sections, removing all loose particles and dust from the roughened stepped surface, the grooves, and the area where the wing wall foundation has been chiseled away; during the reinforcement installation, first hoisting the prefabricated skeleton of the vertical main reinforcement and horizontal distribution reinforcement of the heightened side wall into place as a whole, then inserting one end of the L-shaped structural reinforcement used for pouring the vertical inlay into the area where the wing wall foundation has been chiseled away, and binding the other end to the reinforcement skeleton of the heightened side wall; before pouring concrete, sprinkling water on the cleaned stepped surface, grooves, and the area where the foundation has been chiseled away.

8. The construction method for step-type removal, patching, heightening, and extension of railway culvert wing walls according to claim 7, characterized in that, The reinforcement installation also includes: before the reinforcement cage of the heightened side wall is in place, drilling holes with a diameter 4 mm to 6 mm larger than the diameter of the main reinforcement at the design position of the vertical main reinforcement on the stepped surface of the existing wing wall using an electric hammer, with a hole depth of 150 mm; injecting epoxy resin adhesive into the hole, and then inserting the end of the vertical main reinforcement of the heightened side wall into the hole, ensuring an insertion depth of not less than 120 mm; after the epoxy resin has cured, binding and fixing the remaining part of the reinforcement cage of the heightened side wall; for the L-shaped structural reinforcement installed in the area where the foundation of the wing wall is removed, welding a short horizontal steel bar with a length of not less than 200 mm to the outside of the corner between its vertical and horizontal sections, and welding the short steel bar to the L-shaped structural reinforcement to form a triangular support.

9. The construction method for stepped removal, patching, heightening, and extension of railway culvert wing walls according to claim 8, characterized in that, The concrete pouring process specifically includes: starting from the bottom of the area where the wing wall foundation has been removed, the concrete is poured in layers continuously, with each layer not exceeding 500 mm in thickness; when the concrete reaches the lower edge of the transverse groove, a 30 mm diameter immersion vibrator is used to focus on compacting the area inside the groove, inserting the vibrator into the bottom of the groove and slowly withdrawing it to ensure that the groove is completely and densely filled with concrete; when the concrete reaches the height of the step surface, pouring is temporarily stopped, and the concrete surface at the junction of the step surface is roughened with a wooden trowel, and then the concrete for the raised side wall portion is poured upwards; after all the concrete is poured, a permeable geotextile is covered on the top surface of the raised side wall, and drip irrigation is used to keep the geotextile continuously moist for a curing time of not less than 7 days.

10. The method according to claim 1, characterized in that, After forming the vertical insert and heightened sidewall, the process also includes completing the extension construction: constructing a cover plate on the top of the heightened sidewall; constructing the wing wall and foundation of the new extension section in the direction of the existing culvert outside the route; and finally, constructing the waterproof layer of the entire extension culvert and backfilling the culvert back.

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