Construction method for culvert pipe grouting and staged grouting and plugging

Abstract

The invention discloses a construction method for culvert pipe grouting and staged grouting and plugging, and relates to the technical field of culvert pipe plugging. The construction method comprises the following steps that S1, a working face is excavated; s2, culvert pipe inspection; s3, a slurry injection pipe is manufactured; s4, a slurry injection pipe is installed; s5, cleaning the pipeline; s6, culvert pipe downstream rigid plugging body construction; s7, preparing a slurry; s8, pump type selection and grouting equipment; and S9, filling construction sequence. According to the method, drilling in the dam body is avoided through sequential relay grouting, great advantages are achieved on the situation that operation is not allowed for a high dam or a dam crest, the risk of damaging the dam body structure is avoided, and the work amount of a large drilling machine going to the dam is reduced. Sequential relay grouting realizes grout permeation through a non-drilling mode, physical damage to the dam body is avoided, weak parts of the dam body can be reinforced in a targeted mode by accurately controlling the grout diffusion range and pressure, a continuous anti-seepage curtain is formed, and the overall stability of the dam body is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of culvert plugging, in particular to a culvert shotcrete grading and plugging construction method. BACKGROUND

[0002] The culvert plugging technology is a sealing technology for underground pipelines, aiming to prevent water flow, gas or pollutant leakage, and to ensure infrastructure safety and environmental safety. Its application scenarios cover municipal drainage, water conservancy engineering, industrial pipelines, traffic tunnels and other fields, and is one of the core technologies for maintaining urban lifelines. Through physical blocking, material filling or structural reinforcement, the internal or external passage of the culvert is closed to achieve anti-seepage, leakage prevention and structural protection. This ensures the safety of the project, maintains system function, prevents environmental pollution and prolongs the life of the facility.

[0003] However, in the existing culvert plugging technology, the plugged culvert penetrates the dam body, and the upstream overflow well has been plugged and covered with tailings. If the entire section is plugged, the construction difficulty is huge. Through analysis, the damage of the culvert will cause the dam body to collapse, and then cause landslide and dam failure accidents. The damage of the culvert will cause the formation of a leakage passage inside the dam body, and the water flow will wash away the dam filler, gradually forming a cavity or "pipe gushing", and eventually causing local collapse of the dam. Moreover, if the collapse area is located at a key part of the dam, it may trigger a landslide, which further squeezes the culvert or damages the anti-seepage structure, eventually leading to dam failure. After the upstream overflow well is plugged and covered with tailings, if the culvert is damaged or the plugging fails, the tailings may enter the downstream river or groundwater system with the seepage water.

[0004] There are related invention patents on culvert plugging, as follows:

[0005] Chinese patent application number: CN202011220475.3, invention patent name: culvert prefabricated end plate and grouting bag combined plugging structure and construction method, the invention discloses a culvert prefabricated end plate and grouting bag combined plugging structure, which belongs to the technical field of civil engineering. The invention includes a culvert installed at the water delivery place of the dam body, the culvert is filled with a row of grouting bags, and the space of the culvert except the grouting bags is filled with self-compacting concrete, the end of the culvert is provided with a culvert prefabricated end plate, at least two rows of grouting holes with downward ports are arranged in the dam body along the axis of the culvert, one of which penetrates the culvert, and the ports of the other grouting holes are within 0.5m of the lateral side of the culvert. The invention can improve the construction efficiency of culvert plugging, reduce the construction difficulty, and avoid the formation of new water seepage channels.

[0006] While the aforementioned existing patents can improve the construction efficiency and reduce the difficulty of culvert sealing, and avoid the formation of new seepage channels, they cannot avoid drilling into the dam body. Drilling may disrupt the stress balance of the dam body, especially in soft soil, fault zones, or high water levels, ultimately leading to landslide risks. Moreover, if the mud slurry is not properly used for wall protection after drilling, it may cause the borehole wall to collapse, expanding the damage area of ​​the dam body. The original seepage prevention structure of the dam body may also be cut off by drilling, forming new seepage channels, resulting in cavities around the dam body, directly threatening the stability of the dam body. Summary of the Invention

[0007] The purpose of this application is to provide a construction method for staged grouting and sealing of culverts, which solves the problem that existing culvert sealing technologies require drilling into the dam body.

[0008] A construction method for staged grouting and sealing of culverts, specifically including the following steps:

[0009] A construction method for staged grouting and sealing of culverts, characterized by the following steps:

[0010] S1, Working face excavation: A cofferdam is built at the outlet of the energy dissipation well, i.e., the culvert outlet, using clay to fill the cofferdam. After the filling is completed, a water-stopping curtain is formed using cement-soil mixing piles. After the water-stopping curtain is completed, the water inside the curtain is pumped out, the bottom silt is cleaned, and the energy dissipation well is demolished.

[0011] S2, Culvert Inspection: Pipeline robots are used to inspect the inside of culverts for serious damage, large seepage flow, and large uneven settlement. The corresponding construction plan needs to be adjusted and optimized in a timely manner according to the condition inside the culvert. When the thickness of the tailings mud is large and affects the operation of the robot, pipeline cleaning should be carried out first.

[0012] S3, Fabrication of grouting pipes: Fabricate several grouting pipes. The length of the grouting pipes is optimized according to the site conditions. The grouting pipes are made by splicing single geological pipes. A high-pressure gate valve is placed at a certain position from the grouting port. A variable diameter grouting pipe is installed on one side of the high-pressure gate valve. The grouting pipe body is welded to the pipe head side of the variable diameter grouting pipe. The grouting pipe body adopts a special design to prevent the grout outlet from being blocked.

[0013] S4, Install the grouting pipe: After the grouting pipe is made, use a hydraulic jack to gradually push the single steel pipe in. When the depth reaches 5-6m, connect another steel pipe and continue pushing until the specified depth is reached.

[0014] S5, Pipeline cleaning: Use the pump to directly flush the pushed-in grouting pipe and the main body of the injection pipe. Depending on the blockage in the pipe, choose to flush while pushing in or flush after the main body of the injection pipe is pushed in. Stop flushing when the flushed water is not obviously turbid. At the same time, do a good job of pumping out the flushing water in the cofferdam.

[0015] S6, Rigid sealing body downstream of culvert: The rigid sealing body is poured from the culvert inlet. It can be directly completed by concrete pump and manual labor. At the same time, a reinforced concrete top slab is set at the outer end of the culvert.

[0016] S7, Grout preparation: Cement grout filling can only be carried out 72 hours after the rigid sealing section is poured;

[0017] S8, Pump selection and grouting equipment: Pump working pressure is 0-10MPa, and the grouting pump pressure is strictly controlled during the grouting process;

[0018] S9, Filling construction sequence: including pipeline 1, pipeline 2, pipeline 3 and pipeline 4.

[0019] As a further improvement of the present invention, in step S1, the cofferdam has dimensions of 15m * 35m, the top of the clay dam is 0.9-1.1m above the water surface, the top width of the clay dam is 2.5m, the inner slope ratio of the cofferdam is 1:2, and the compaction degree of the clay in the cofferdam is 0.97. Through cofferdam construction, cutoff wall construction, and dewatering and dredging, waterless working conditions are created for culvert inspection and repair, avoiding the risks of underwater construction.

[0020] As a further improvement of the present invention, in step S3, the length of a single grouting pipe is 6m, and the two grouting pipes are connected by threads, with a perforated pipe provided near the grout outlet. The threaded connection transmits stress through mechanical engagement, and compared to the local heat-affected zone of welding or the risk of bolt loosening in flange connections, the threaded connection is less prone to failure under repeated grouting pressure fluctuations.

[0021] As a further improvement of the present invention, in step S3, an irregularly shaped flow channel is formed inside the grouting pipe body, and teardrop-shaped baffles are fixedly connected to the center of the arc of the irregularly shaped flow channel inside the grouting pipe body. The unidirectional flow characteristics of the flow channel design can reduce pressure fluctuations during the grouting process, maintain a stable grouting rate, avoid frequent shutdowns for cleaning due to blockage, and significantly shorten the construction cycle.

[0022] As a further improvement of the present invention, in step S4, a roller is installed at a suitable position at the bottom end of the grouting pipe, and a camera is installed at the grout outlet of the grouting pipe. During the advancement of the grouting pipe, it needs to traverse soil layers, rock layers, or existing structures. Traditional straight pipes experience significant sliding friction with the contact surface, especially in soft soil or aquifers, where adsorption can easily cause the pipe to become stuck. The roller converts sliding friction into rolling friction, reducing friction and significantly decreasing the external force required for advancement, thus reducing the labor intensity of workers.

[0023] As a further improvement of the present invention, in step S6, the length of the cast rigid sealing body is 10m, and the amount of concrete is approximately 7.85m³. 3Under the influence of groundwater flow or grouting pressure, the sealing material must withstand hydraulic erosion. A 10m length can form a thick-walled barrier layer, extending the water flow path and reducing the seepage rate.

[0024] As a further improvement of the present invention, in step S7, the water-cement ratio (W:C) of the cement slurry is 1:1 to 0.8:1, the cement is P.O42.5 silicate cement, and the amount of reinforcing waterproofing agent and special powder added to the cement accounts for 12% of the cement mass. For the culvert leakage point, a controlled grouting of cement and water glass is performed, with a cement slurry to water glass C:S ratio of 1:0.5. The two-component slurry is injected synchronously through a two-component grouting pump, and reacts rapidly upon contact to form a gel. The higher the water glass content, the faster the setting; the higher the cement content, the longer the setting time. The 1:0.5 ratio balances construction speed and final strength, making it suitable for rapid sealing of culvert leakage.

[0025] As a further improvement of the present invention, the volume of the filling cement grout is 173m³. 3 The enhanced waterproofing agent is used to achieve a grout stone formation rate of over 70%, and the total grouting volume of the cement grout is 247m³. 3 The cement content is 186 tons, and the reinforced waterproofing agent and special powder are expected to use 22 tons. During the preparation of the grout, the cement grout and the reinforced waterproofing agent are mixed evenly in proportion. The resulting stone structure not only has high strength but also enhanced adhesion to the surrounding soil or rock, forming a "rigid-flexible" composite structure that adapts to culvert deformation and prevents sealing failure due to uneven settlement.

[0026] As a further improvement of the present invention, in step S9, the filling construction sequence is as follows: starting from pipeline one, all valves of the remaining grouting pipes are opened for observation. Due to the slope of the culvert and the weight of the grout, the grout will gradually accumulate and settle from bottom to top in the culvert. When grout returns from pipeline two, grouting is stopped, the valve of pipeline one is closed, and filling begins from pipeline two. When grout returns from pipeline three, grouting is stopped, the valve of pipeline two is closed, and grouting begins from pipeline three. When grout returns from pipeline four, grouting in pipeline three is stopped, the valve is closed, and grouting begins from pipeline four until grouting is completed. Culverts usually have a certain slope, and the grout flows and accumulates from bottom to top under the action of gravity. When grouting pipeline one, the grout preferentially fills the low-lying area at the bottom, and gradually covers the entire cross-section as the liquid level rises, avoiding local cavities or weak layers caused by uneven grout flow in traditional grouting.

[0027] Compared with the prior art, the beneficial effects of this invention are as follows:

[0028] 1. Sequential relay grouting avoids drilling into the dam body, which is a significant advantage for high dams or dam crests where work is not permitted. It mitigates the risk of damaging the dam structure and reduces the workload of large drilling rigs. Sequential relay grouting achieves grout penetration through non-drilling methods, avoiding physical damage to the dam body. Furthermore, by precisely controlling the grout diffusion range and pressure, it can specifically reinforce weak points in the dam body, forming a continuous anti-seepage curtain and enhancing the overall stability of the dam. Sequential relay grouting employs a segmented, layered construction strategy, allowing for parallel operations or rapid connections, reducing waiting time between processes, and significantly shortening the overall construction period compared to traditional drilling grouting.

[0029] 2. By utilizing the grout's own weight and slope to accumulate without intermediate partitions, and relying on the grout's fluidity, weight, and solidification properties, grouting is carried out in relays using grouting pipes of varying lengths. Grouting pipes of different lengths can be used for segmented and layered relay grouting, achieving a continuous operation mode of simultaneous flow, solidification, and relay, avoiding the waiting time of traditional segmented construction and improving overall construction efficiency. Furthermore, the grout, relying on its own weight and slope flow, can evenly fill cracks and pores in the dam body, forming a continuous and dense seepage-proof layer, improving the dam's impermeability and long-term stability.

[0030] 3. A uniquely shaped flow channel is created within the grouting pipe body, with teardrop-shaped baffles fixed at the center of the arc-shaped channel. This special flow channel design achieves unidirectional flow characteristics of "low resistance in the forward direction and high resistance in the reverse direction" through fluid inertia. When the grout flows forward, the flow channel smoothly guides the fluid; when flowing in the reverse direction, eddies and a surge in local resistance are generated at the bends of the flow channel, effectively suppressing grout backflow and reducing particle deposition caused by backflow. The unidirectional flow characteristic of the flow channel design reduces pressure fluctuations during grouting, maintains a stable grouting rate, avoids frequent shutdowns for cleaning due to blockages, and significantly shortens the construction cycle. In high-pressure grouting scenarios, the turbulence enhancement effect of the flow channel prevents premature solidification of the grout inside the pipe, while reducing the risk of chain blockages caused by particle deposition, such as pipe diameter reduction and pressure surges.

[0031] 4. The curved pipe design of the grout outlet allows for flexible adjustment of the grouting direction. The perforated pipe structure disperses the grout, resulting in a more uniform grouting than straight-outlet grouting and preventing silt and gravel from clogging the grout outlet. The perforated pipe layout close to the grout outlet further shortens the grout spraying path, reduces secondary blockages caused by residue inside the pipe, and ensures continuous and stable grouting throughout the entire process. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart of the steps of the present invention.

[0034] Figure 2 This is a schematic diagram of the installation of the culvert sealing in this invention.

[0035] Figure 3 This is a schematic plan view of the culvert sealing section in this invention.

[0036] Figure 4 This is a diagram illustrating the queue length calculation process of the present invention.

[0037] In the figure: 1. Grouting pipe body; 2. Irregular flow channel; teardrop-shaped baffle. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] A construction method for staged grouting and sealing of culverts, such as... Figure 1 As shown, it includes the following steps:

[0040] S1, Working Face Excavation: At the outlet of the energy dissipation well (i.e., culvert), a 15m*35m cofferdam is constructed using clay filling. The top of the clay dam is 1m above the water surface, with a top width of 2.5m, an inner slope ratio of 1:2, and a compaction degree of 0.97. After filling, cement-soil mixing piles are used to form a water-stop curtain to increase the seepage resistance and stability of the clay dam. At the connection with the dam body, bagged clay + composite geomembrane can be used for local seepage prevention. After the water-stop curtain construction is completed, the water inside the curtain is pumped out, the bottom silt is cleaned, and the energy dissipation well is dismantled.

[0041] Using different proportions of key parameters in the construction of culvert closure cofferdams as a comparison condition, the data advantages of this invention are analyzed in detail, and the specific comparison table is as follows:

[0042] Table 1. Comparison of Key Parameters for Culvert Closure Cofferdam Construction at Different Proportions and Analysis of the Advantages of Existing Data

[0043]

[0044] Based on Table 1 above, it can be concluded that an inner slope ratio of 1:2 combined with a compaction degree of 0.97 ensures that the dam body does not experience lateral slippage after dewatering, while avoiding excessive material consumption as with a 1:2.5 slope ratio. The clay dam, in conjunction with the cutoff wall, minimizes the dam body porosity with a compaction degree of 0.97. Combined with local reinforcement using bagged clay and a composite geomembrane, the permeability coefficient meets the requirements for waterless operation during culvert sealing construction. The 2.5m top width perfectly matches the operating space of the cement-soil mixing pile construction equipment, eliminating the need for additional widening or narrowing. The 15m × 35m cofferdam precisely covers the construction area, saving approximately 30% of clay compared to larger sizes, and avoiding secondary construction due to insufficient water containment compared to smaller sizes. The dam crest is 1m above the water surface, which can handle normal water level fluctuations without increasing the filling period and material costs as with a 1.5m super-high dam.

[0045] S2, Culvert Inspection: A relevant surveying unit will be commissioned to inspect the interior of the culvert using equipment such as pipeline robots. Images and other data will be transferred to the design unit for review and confirmation. If the culvert shows no severe damage, large seepage flow, or significant uneven settlement, and the conditions deviate significantly from the default design conditions, the corresponding construction plan must be adjusted and optimized promptly. Additionally, since the thickness of the tailings sediment inside the culvert is unknown, if the tailings sediment is thick enough to affect robot operation, pipeline cleaning can be performed first.

[0046] S3, Fabrication of the injection pipe: (e.g., ...) Figure 2 As shown, four grouting pipes are fabricated with lengths of 15m, 100m, 160m, and 230m (measured from the culvert inlet). The specific lengths can be optimized based on site conditions. The grouting pipes are constructed by splicing single geological pipes, each 6m long, with threaded connections between pipes. The inner diameter of each pipe is 100mm, and the wall thickness should not be less than 6mm. A DN100 / PN6.4MPa high-pressure gate valve is installed approximately 15cm from the grouting inlet. A Φ75mm*0.5m reducing grouting pipe is installed on one side of the gate valve, and a one-inch grouting pipe is welded to the grouting pipe head and one side. A bend is used at one end of the grout outlet, and a perforated pipe is installed near the outlet to prevent blockage.

[0047] Using different proportions of key parameters for duct sealing and grouting pipes as a comparison condition, the data advantages of this invention are analyzed in detail, and the specific comparison table is as follows:

[0048] Table 2 Comparison of Key Parameters of Culvert Sealing Percussion Pipe at Different Proportions and Analysis of the Advantages of Existing Data

[0049]

[0050] Based on Table 2 above, it can be concluded that the gradient length design of 5m / 100m / 160m / 230m perfectly covers the sealing requirements of the entire culvert from the inlet to the far end, avoiding blind spots in the far-end sealing caused by short gradients, or waste of pipe material in long gradients. The 100mm inner diameter combined with the 6mm wall thickness ensures both grout flow and control of pressure loss, ensuring that the grouting pressure at the 230m far end can still reach 2-3MPa, thus solving the problem of "oversaturation at the near end and emptiness at the far end" in long-distance culvert grouting. Moreover, the bend design of the grout outlet allows for flexible adjustment of the grouting direction, and the perforated pipe structure can disperse the grout spray, which is more uniform than straight-outlet grouting and avoids clogging of the grout outlet by silt and gravel. The layout of the perforated pipe close to the grout outlet further shortens the grout spray path, reduces secondary blockage caused by residue in the pipe, and ensures continuous and stable grouting throughout the entire process.

[0051] S4. Install the grouting pipe: After the grouting pipe is fabricated, use a hydraulic jack or hoist to gradually advance a single steel pipe. When the depth reaches 5-6m, connect another steel pipe and push it in again until the designated depth is reached. To facilitate the installation of the grouting pipe, wheels should be installed at appropriate locations on the grouting pipe. A camera should also be installed at the grout outlet of the grouting pipe to facilitate the observation of the working conditions inside the culvert.

[0052] S5, Pipeline Cleaning: Pipeline cleaning can be performed by directly flushing the pipe with a water pump after it has been pushed in. Flushing can be done while pushing in the pipe, or flushing can be done after the grouting pipe has been pushed in. Flushing can be stopped when the flushed water is no longer obviously turbid, and the flushing water inside the cofferdam should be pumped out at the same time.

[0053] S6, Rigid sealing section downstream of the culvert: A 10m long rigid sealing section will be poured starting from the culvert inlet, using C30 concrete. Due to the short length, a concrete pump can be used in conjunction with manual labor. A reinforced concrete top slab will be installed at the outer end of the culvert, with a concrete volume of approximately 7.85m³. 3 .

[0054] S7, Grout Preparation: Grouting can only be carried out 72 hours after the rigid sealing section is poured. The water-cement ratio of the cement grout is W:C = 1:1~0.8:1, and P.O42.5 silicate cement is selected. The addition of both the reinforcing waterproofing agent and the special powder accounts for 12% of the cement mass. For grout leakage in the culvert, controlled grouting can be carried out using a cement-water glass two-component grout, where the cement grout-water glass C:S ratio is 1:0.5. Considering the uncertainty of the grout filling in the culvert, the preliminary estimate of the grout volume is 173m³. 3 After adding a high-efficiency waterproofing agent, the grout stone formation rate can reach over 70%, and the total grouting volume is expected to be 247m³. 3The cement content is 186 tons. The amount of reinforcing waterproofing agent and special powder is considered to be 12% of the cement content, estimated to require 22 tons. The actual grout injection volume will be based on the monitored thickness. Grouting should be continuous and uninterrupted in principle. When preparing the grout, the cement grout and reinforcing waterproofing agent must be mixed in the correct proportions and thoroughly stirred. The grout will be delivered using a dedicated grouting pump.

[0055] Using different specifications of key parameters for culvert sealing grout preparation as a comparative condition, the data advantages of this invention are analyzed in detail, and the specific comparison table is as follows:

[0056] Table 3. Comparison of Key Parameters for Culvert Plugging Grout Preparation at Different Specifications and Analysis of the Advantages of Existing Data

[0057]

[0058] Based on Table 3 above, it can be concluded that a water-cement ratio of 1:1 to 0.8:1 is the "golden ratio" for rigid sealing grout: it ensures both grout fluidity and the density of the stone body, achieving a 28-day compressive strength of 15-20 MPa, which can withstand the pressure of the surrounding soil and groundwater seepage pressure. A cement-water glass two-component grout with a 1:0.5 ratio and a gel time precisely controlled at 30-60 seconds can achieve "grouting and sealing" at culvert leakage points, avoiding the problems of slow-setting grout loss or excessively rapid setting causing blockage. The combined use of the two-component grout and conventional cement grout not only solves the emergency sealing of localized leakage but also ensures overall filling density, conforming to the construction logic of "seal the leak first, then fill" for culvert sealing.

[0059] S8, Pump selection and grouting equipment: Based on work experience, the pump working pressure is 0-10MPa, and the grouting pump pressure is strictly controlled during the grouting process.

[0060] S9, Filling construction sequence: as follows Figure 2 As shown, during filling, it begins with the 15m short pipe (pipeline one). All valves on the remaining grouting pipes are opened for observation. Due to the culvert slope and the weight of the grout, the grout will gradually accumulate and settle from bottom to top within the culvert. When grout begins to return from pipeline two, grouting is stopped, the valve on pipeline one is closed, and filling begins from pipeline two. When grout returns from pipeline three, grouting is stopped, the valve on pipeline two is closed, and grouting begins from pipeline three. When grout returns from pipeline four, grouting in pipeline three is stopped and the valve is closed, and grouting begins from pipeline four until grouting is complete.

[0061] Implementation Precautions: Before the formal sealing operation, a 1:10 scale physical model should be prepared for testing to verify whether the fluidity and density of the grout, initial setting time, final setting time, initial setting strength, and final setting strength meet the sealing requirements. Simultaneously, the dimensions of the grout pump pipe and the spacing of the grout outlets should be further optimized, adjusted, and confirmed based on the mix proportions and the fluidity of the grout. Furthermore, the impact of culvert seepage on the cement grout properties should be reasonably considered, especially the impact of changes in the mix proportions on material properties. Since the internal working conditions of the culvert are unknown, collecting image data of the culvert's interior before and during construction is particularly important.

[0062] Grouting and sealing involve a certain pumping pressure; therefore, when using welding for the grouting pipes, it is essential to ensure that the weld strength meets requirements and that the welded section does not experience burn-through or grout leakage. Proper drainage should be implemented within the cofferdam to ensure that seepage water and cleaning water within the culvert are promptly drained away, preventing any impact on the safety of the entire cofferdam or the construction progress. The length of the grouting pipes should be adjusted appropriately based on the internal conditions, and the grout filling sequence should be carefully controlled.

[0063] Grouting pipelines should be connected using internal joints, with the joints threaded to the pipelines. Bending and breakage of the pipelines should be avoided during installation. The concrete sealing the culvert outlet end should be vibrated to ensure compaction; the concrete strength grade should be C30. The concrete surrounding the grouting pipelines within the culvert sealing section must be ensured to be dense. To improve the early strength of the concrete, an appropriate amount of concrete accelerator can be added during mixing. Furthermore, the cement slurry mixing time should not be less than 3 minutes.

[0064] Grouting should be carried out continuously without interruption. The grouting pipeline should be securely installed and pressure-tested to prevent leakage. Grouting should be performed by qualified personnel, who should adjust the grouting pressure according to the pressure gauge at the grouting port and monitor the flow rate within the grouting pipe based on pressure gauge readings. During grouting, a designated person should accurately count the grout volume and regularly predict the grout filling position within the culvert. If grout seepage occurs during grouting, especially at the dam foundation, grouting should be stopped immediately, the grout in the grouting pipe should be drained, and the pipe should be flushed with clean water. Grouting can only continue after the cause of the seepage has been identified and the seepage point has been treated promptly. To ensure the grout solidifies to a depth of 230m within the culvert, a test should be conducted before grouting to confirm the grout solidification rate and determine the appropriate grout injection volume. Site surveys indicate that the terrain around the dam toe is relatively flat; temporary construction roads paved with crushed stone and soil can be used for equipment entry and subsequent material transportation.

[0065] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction method for staged grouting and sealing of culverts, characterized in that, Specifically, the steps include the following: S1, Working face excavation: A cofferdam is built at the outlet of the energy dissipation well, i.e., the culvert outlet, using clay to fill the cofferdam. After the filling is completed, a water-stopping curtain is formed using cement-soil mixing piles. After the water-stopping curtain is completed, the water inside the curtain is pumped out, the bottom silt is cleaned, and the energy dissipation well is demolished. S2, Culvert Inspection: Pipeline robots are used to inspect the inside of culverts for serious damage, large seepage flow, and large uneven settlement. The corresponding construction plan needs to be adjusted and optimized in a timely manner according to the condition inside the culvert. When the thickness of the tailings mud is large and affects the operation of the robot, pipeline cleaning should be carried out first. S3, Making grouting pipes: Make several grouting pipes. The length of the grouting pipes is optimized according to the site. The grouting pipes are made by splicing single geological pipes. A high-pressure gate valve is placed at a certain position from the grouting port. A variable diameter grouting pipe is installed on one side of the high-pressure gate valve. The grouting pipe body (1) is welded to one side of the variable diameter grouting pipe head. The grouting pipe body (1) is specially designed to prevent the grouting port from being blocked. S4, Install the grouting pipe: After the grouting pipe is made, use a hydraulic jack to gradually push the single steel pipe in. When the depth reaches 5-6m, connect another steel pipe and continue pushing until the specified depth is reached. S5, Pipeline cleaning: Use the pump to directly flush the grouting pipe and the grouting pipe body (1) that have been pushed in. Depending on the blockage in the pipe, choose to flush while pushing in or flush after the grouting pipe body (1) has been pushed in. Stop flushing when the water is not obviously turbid. At the same time, do a good job of pumping out the flushing water in the cofferdam. S6, Rigid sealing body downstream of culvert: The rigid sealing body is poured from the culvert inlet. It can be directly completed by concrete pump and manual labor. At the same time, a reinforced concrete top slab is set at the outer end of the culvert. S7, Grout preparation: Cement grout filling can only be carried out 72 hours after the rigid sealing section is poured; S8, Pump selection and grouting equipment: Pump working pressure is 0-10MPa, and the grouting pump pressure is strictly controlled during the grouting process; S9, filling construction sequence: including pipeline one, pipeline two, pipeline three and pipeline four.

2. The construction method for staged grouting and sealing of culverts as described in claim 1, characterized in that: In step S1, the cofferdam has dimensions of 15m*35m, the top of the clay dam is 0.9-1.1m above the water surface, the top of the clay dam is 2.5m wide, the inner slope ratio of the cofferdam is 1:2, and the compaction degree of the clay in the cofferdam is 0.

97.

3. The construction method for staged grouting and sealing of culverts as described in claim 1, characterized in that: In step S3, the length of a single grouting pipe is 6m, the two grouting pipes are connected by a thread, and a perforated pipe is provided near the grout outlet.

4. The construction method for staged grouting and sealing of culverts as described in claim 1, characterized in that: In step S3, an irregular flow groove (2) is opened inside the grouting pipe body (1), and a teardrop-shaped baffle (3) is fixedly connected inside the grouting pipe body (1) at the arc-shaped middle part of the irregular flow groove (2).

5. The construction method for staged grouting and sealing of culverts as described in claim 4, characterized in that: In step S4, a roller is installed at a suitable position at the bottom end of the injection pipe, and a camera is installed at the injection pipe outlet.

6. The construction method for staged grouting and sealing of culverts as described in claim 5, characterized in that: In step S6, the length of the cast rigid sealing body is 10m, and the amount of concrete is approximately 7.85m³. 3 .

7. The construction method for staged grouting and sealing of culverts as described in claim 3, characterized in that: In step S7, the water-cement ratio W:C of the cement slurry is 1:1 to 0.8:1, the cement is P.O42.5 silicate cement, and the amount of the cement-reinforcing waterproofing agent and special powder added accounts for 12% of the cement mass. For the culvert leakage point, cement and water glass double liquid grout is used for controlled grouting, and the ratio of cement slurry to water glass C:S is 1:0.

5.

8. The construction method for staged grouting and sealing of culverts as described in claim 7, characterized in that: The volume of the cement grout used for filling is 173m³. 3 The enhanced waterproofing agent is used to achieve a grout stone formation rate of over 70%, and the total grouting volume of the cement grout is 247m³. 3 The amount of cement is 186t, and the amount of reinforcing waterproofing agent and special powder is expected to be 22t. When the slurry is made, the cement slurry and the reinforcing waterproofing agent are mixed evenly in proportion.

9. The construction method for staged grouting and sealing of culverts as described in claim 1, characterized in that: In step S9, the filling construction sequence is as follows: starting from pipeline one, all valves of the other grouting pipes are opened for observation at the beginning of pipeline one. Due to the slope of the culvert and the weight of the grout, the grout will gradually accumulate and settle from bottom to top in the culvert. When grout returns from pipeline two, grouting is stopped, the valve of pipeline one is closed, and filling begins from pipeline two. When grout returns from pipeline three, grouting is stopped, the valve of pipeline two is closed, and grouting begins from pipeline three. When grout returns from pipeline four, grouting in pipeline three is stopped, the valve is closed, and grouting begins from pipeline four until grouting is completed.

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