Non-improved high liquid limit clay backfill maintenance construction method

Abstract

The invention discloses a non-improved high-liquid-limit clay backfill maintenance construction method. According to the method, before construction, earthwork related information is determined, materials are screened, teams are organized, debugging equipment is prepared, and safety measures are formulated; during substrate treatment, sundries and accumulated water are cleaned, leveling and tamping are conducted, and special areas and soft soil foundations are treated; grooving interlocking alternate filling is adopted, grooving is conducted after high-liquid-limit clay filler is wetted, and clay is used for covering and compacting to form interlocking; monitoring the moisture content in real time by controlling the initial moisture content and regulating and controlling the moisture by means of a model; and applying a composite compaction process, initially pressing by a vibratory roller, reinforcing the edge of the notch groove by a battering ram, and regularly crushing the surface layer. The method solves the problem of backfilling of high-liquid-limit clay, overcomes the problems of difficult compaction and uneven settlement caused by the characteristics of the clay, avoids the defects of the traditional layered rolling technology, and effectively guarantees the backfilling quality and the engineering safety.

Description

Technical Field

[0001] The invention belongs to the technical field of earth backfill construction, and in particular relates to a non-improved high liquid limit clay backfill maintenance construction method. Background Art

[0002] In the field of modern engineering construction, earth backfill is a basic and key construction link, and its construction quality is directly related to the stability and safety of the entire project. High liquid limit clay (clay with a liquid limit index greater than 50) is widely used in engineering construction in many regions. However, due to its special physical and mechanical properties, it has caused a series of thorny problems in backfill construction.

[0003] High liquid limit clay has a high water content, which makes it difficult to achieve the ideal density during compaction. Excessive water takes up space in the soil, hindering the close arrangement of soil particles. Even after repeated rolling, it is difficult to effectively improve the density of the soil. At the same time, high liquid limit clay has poor water permeability and water is not easy to drain. Under the action of long-term dry-wet cycles, the volume of the soil will change significantly, leading to uneven settlement. This uneven settlement will cause problems such as undulating road surfaces and tilted building foundations, seriously affecting the normal use of the project and structural safety.

[0004] The high compressibility and low strength of high liquid limit clay also bring great challenges to backfill construction. High compressibility means that the soil will produce large compression deformation when bearing the load of the upper structure, which is extremely unfavorable for projects with high requirements for deformation control. Low strength makes the bearing capacity of the soil insufficient and unable to effectively bear the load transmitted by the upper structure. In severe cases, it may cause roadbed settlement, slope collapse and other diseases, posing a serious threat to project safety.

[0005] Most of the existing non-improved processes rely on layered rolling technology, but this technology has obvious defects when dealing with high liquid limit clay backfill. On the one hand, due to the special properties of high liquid limit clay, repeated rolling is often required to achieve the design density requirements. This not only consumes a lot of time and prolongs the project period, but also increases mechanical loss and labor costs, greatly increasing the cost of project construction. On the other hand, the connection between the filling layers under the layered rolling technology is not tight enough, and the interlayer bonding is weak. Under the influence of long-term external forces or complex environments, interlayer separation is prone to occur, resulting in a decrease in overall stability and failure to meet the long-term stability requirements of the project. In addition, the water content of high liquid limit clay fluctuates greatly and has poor permeability, and it is difficult for traditional processes to effectively control its water content. When the soil is too dry, cracks are likely to occur, reducing the integrity and strength of the soil; when the soil is too wet, "spring soil" will be formed, and normal compaction operations cannot be carried out, which greatly affects the backfill quality.

[0006] In summary, the existing high liquid limit clay backfill construction technology has many shortcomings, and a new construction method is urgently needed to solve these problems, achieve efficient backfill and long-term stability of high liquid limit clay, ensure the quality and safety of the project, and reduce the cost of project construction. Summary of the invention

[0007] To this end, the present invention provides a non-improved high liquid limit clay backfill maintenance construction method to solve the problem of non-improved high liquid limit clay backfill maintenance, overcome the high water content, poor permeability, high compressibility, low strength and other characteristics caused by the difficult compaction, uneven settlement problems, avoid the traditional layered rolling technology defects of low efficiency, weak interlayer bonding, difficulty in regulating water content, to ensure backfill quality and engineering safety.

[0008] In order to achieve the above object, the present invention provides the following technical solution: a non-improved high liquid limit clay backfill maintenance construction method, comprising the following steps:

[0009] Preparation before construction: determine the source and location of backfill earthwork, screen and process earthwork materials, organize construction teams, prepare and debug construction equipment, and formulate safety measures for the construction site;

[0010] Backfill base treatment: clean up debris and accumulated water on the backfill base, level and compact the backfill base, and treat special areas and soft soil foundations in the backfill base, including paddy fields, reservoirs, and fish ponds;

[0011] Grooving interlocking alternating filling: Wet high liquid limit clay filler, fill and compact it, then make grooves, then cover and fill with clay and compact it, using the difference in compressibility of different soils to form an interlocking effect;

[0012] Dynamic moisture control: Control the initial moisture content of high liquid limit clay, monitor the moisture content of backfill soil in real time, spray or drain according to the monitored moisture content of backfill soil, and control the moisture with the help of moisture migration model;

[0013] Composite compaction: Use a vibratory roller for initial compaction, reinforce the groove edges with an impact rammer, crush the surface layer after each set number of filling layers, and repeat the composite compaction operation until the designed backfill elevation is reached.

[0014] As the preferred construction method for non-improved high liquid limit clay backfill maintenance, during the interlocking and alternating filling process of the grooves, the formula for calculating the amount of water required to be added when the high liquid limit clay filler is wet is:

[0015] m water =m soil ×(w t -w 0 )

[0016] In the formula, m water is the amount of water to be added, m soilis the mass of high liquid limit clay, wt is the target water content, w 0 is the initial water content.

[0017] As the preferred construction method for backfill maintenance of non-improved high liquid limit clay, during the interlocking alternating filling process, the interlocking structure of the grooves changes the stress state of the soil. The shear strength of the interlocking structure of the grooves that forms an interlocking effect by utilizing the difference in compressibility of different soils is:

[0018]

[0019] In the formula, τ is the shear strength, c is the cohesion, σ is the normal stress, is the internal friction angle.

[0020] As the optimal solution for the non-improved high liquid limit clay backfill maintenance construction method, the established moisture migration model formula is as follows during the dynamic moisture control process:

[0021]

[0022] Where q is the water flux, D is the soil water diffusivity, θ is the volumetric water content, and z is the depth coordinate.

[0023] As a preferred solution for the construction method of backfill maintenance of non-improved high liquid limit clay, during the interlocking and alternating filling process, excavation equipment is used to mix the high liquid limit clay on the backfill ground line after the base treatment is completed to carry out grooving operations in the filling area. The grooving depth is adapted to the thickness of the filling area to form an effective embedded structure with the subsequent filling clay.

[0024] As a preferred solution for the non-improved high liquid limit clay backfill maintenance construction method, during the groove interlocking alternating filling process, the non-improved high liquid limit clay completely fills the groove area and forms a continuous and dense clay interlocking area on the surface of the groove area.

[0025] As the preferred solution for the construction method of non-improved high liquid limit clay backfill maintenance, during the dynamic moisture control process, the nozzles of the atomizing spray system are optimized based on the geometric characteristics of the backfill area to achieve uniform coverage of the backfill area and the clay interlocking area after the high liquid limit clay is mixed with water mist.

[0026] As the preferred solution for the construction method of non-improved high liquid limit clay backfill maintenance, the dynamic moisture control process also includes laying geotextiles along the top and slope of the backfill structure, and building a distributed monitoring network in combination with IoT humidity sensors to collect moisture content data of backfill soil in different spatial locations.

[0027] As the preferred construction method for backfill maintenance of non-improved high liquid limit clay, during the composite compaction process, an impact rammer is used to reinforce and compact the edges of the grooved area to improve the interface bonding strength and density between the grooved area and the surrounding soil.

[0028] As the preferred construction method for non-improved high liquid limit clay backfill maintenance, after each layer of grooved interlocking is completed, the bonding quality of the grooved area and the clay interlocking area is evaluated by combining non-destructive testing and sampling testing.

[0029] The present invention has the following advantages:

[0030] First, by clearing the debris and accumulated water on the base, good basic conditions can be created for subsequent backfill construction, avoiding the impact of debris and accumulated water on the combination of backfill soil and the base, and preventing uneven settlement caused by an unstable foundation. Leveling and compacting the base can improve the bearing capacity of the base, so that the backfill soil can be evenly stressed and the stability of the backfill body can be ensured. Treatment of special areas and soft soil foundations, such as draining paddy fields, reservoirs, fish ponds and other areas in advance, and using replacement or reinforcement methods for soft soil foundations can enhance the stability and bearing capacity of the base, effectively prevent settlement and deformation of the backfill body caused by base problems, and improve the safety and durability of the entire project;

[0031] Second, wet high liquid limit clay fillers can improve physical properties and make them easier to compact. Grooving operations can increase the friction and bite force between the filling layers, and utilize the interlocking effect formed by the difference in compressibility of different soils to enhance the integrity and stability of the backfill soil. This interlocking structure can effectively resist the lateral deformation and sliding of the soil, improve the shear strength of the soil, and reduce the generation of cracks, thereby ensuring the long-term stability of the backfill. Through the grooved interlocking alternating filling process, the compaction effect of the backfill soil is better, and a higher density can be achieved, further improving the quality of the project;

[0032] Third, by real-time monitoring of the moisture content of the backfill soil and automatically spraying or draining water according to the situation, the moisture content of the backfill soil can be adjusted in time to avoid problems such as compaction difficulties and "spring soil" caused by excessively high or low moisture content. With the help of the moisture migration model, the moisture can be accurately controlled, which can provide an in-depth understanding of the migration law of moisture in the backfill soil, achieve precise control of moisture, ensure that the backfill soil can maintain stable performance under different environmental conditions, and improve the quality and reliability of the backfill project;

[0033] Fourth, using impact rammers to reinforce the edges of the grooves can enhance the compaction effect of the grooves, ensure the close combination of the grooves and the surrounding soil, and further improve the interlocking effect. Crushing the surface layer after each certain number of layers can break the compacted layer of the soil, so that the subsequent filling soil can be better combined with the compacted soil, improving the integrity of the entire backfill. Through repeated operations of the composite compaction process, the backfill soil can reach the density and stability required by the design, ensuring that the project quality meets the standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0035] Figure 1 A schematic diagram of a process flow of a non-improved high liquid limit clay backfill curing construction method provided in an embodiment of the present invention;

[0036] Figure 2 It is a schematic diagram of interlocking and alternating filling of grooves in the non-improved high liquid limit clay backfill maintenance construction method provided in an embodiment of the present invention.

[0037] In the figure, 1. Backfill ground line; 2. Filling area after high liquid clay is hydrated; 3. Grooving area; 4. Clay interlocking area; 5. Atomizing spray system; 6. Water mist; 7. IoT humidity sensor. DETAILED DESCRIPTION

[0038] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] See also Figure 1 and Figure 2 The embodiment of the present invention provides a non-improved high liquid limit clay backfill maintenance construction method, comprising the following steps:

[0040] S1. Preparation before construction: determine the source and location of backfill earthwork, screen and process earthwork materials, organize construction teams, prepare and debug construction equipment, and formulate safety measures for the construction site.

[0041] Specifically, by clarifying the source and location of earthwork, the quality of earthwork can be guaranteed to be stable and meet the requirements of the project, while facilitating the planning of transportation routes and improving construction efficiency. Screening and processing earthwork materials can remove impurities and unqualified soil materials, ensure the excellent performance of backfill soil, and avoid affecting the quality of the project due to soil material problems. Organizing a professional construction team and debugging the equipment can ensure the accuracy of construction operation specifications, reduce errors, and speed up the construction progress. Formulate safety measures, starting from personnel safety, equipment operation specifications and other aspects, reduce safety risks, and ensure safe and orderly construction. In actual projects, if the source of earthwork is unknown or the quality is uneven, it may lead to substandard subsequent compaction. For example, a project has many impurities in the earthwork, and multiple voids appear after compaction, affecting the overall structural stability.

[0042] S2. Backfill base treatment: clean up the debris and accumulated water on the backfill base, level and compact the backfill base, and treat the special areas and soft soil foundation in the backfill base, including paddy fields, reservoirs, and fish ponds.

[0043] Specifically, cleaning up debris and accumulated water on the base can eliminate their negative impact on the base's bearing capacity. Debris will prevent the backfill soil from being tightly combined with the base, and accumulated water will reduce the base strength, causing subsequent settlement and other problems. Leveling and compacting the base can increase the density and uniformity of the base, allowing it to better withstand the pressure of the upper backfill soil. For special areas such as paddy fields, reservoirs, fish ponds, and soft soil foundations, due to their poor geological conditions, such as high water content and low bearing capacity, special treatment is required, such as drainage, replacement, and reinforcement, to improve the base's bearing capacity and stability and prevent the backfill from settling and deforming. For example, a project backfilled without draining the base of the paddy field area, resulting in large-scale settlement later, causing the project to be reworked.

[0044] S3. Interlocking and alternating filling: Moisten high liquid limit clay filler, spread and compact it, then make grooves, cover and fill with clay and compact it, using the difference in compressibility of different soil types to form an interlocking effect.

[0045] Specifically, wet high liquid limit clay filler can improve its plasticity and compaction performance, reduce the friction between soil particles, and facilitate compaction to the designed density. After paving and compaction, grooves are cut to increase the contact area and roughness between filling layers. After compaction, different soil types squeeze and inlay each other to form an interlocking structure, which increases the friction and bite force of the soil, changes the stress state, and enhances integrity and stability. According to field tests, the shear strength of the soil using the groove interlocking process is increased by about 30% compared with the traditional layered rolling soil, effectively inhibiting the expansion of transverse cracks. For example, in the test site, more transverse cracks appeared in the area where the groove interlocking process was not used, while the cracks in the area using this process were significantly reduced.

[0046] S4. Dynamic moisture control: Control the initial moisture content of high liquid limit clay, monitor the moisture content of backfill soil in real time, spray or drain according to the monitored moisture content of backfill soil, and control the moisture with the help of moisture migration model.

[0047] Specifically, the water content of high liquid limit clay has a significant impact on the compaction effect and long-term stability. Controlling the initial water content within an appropriate range can enable high liquid limit clay to be compacted in the best state and achieve good density. Real-time monitoring of water content is required to timely grasp the changes in water content. Draining water when the water content is too high can avoid the "spring soil" phenomenon and ensure the compaction effect; spraying water when the water content is too low can prevent the soil from drying and cracking and maintain the integrity of the soil. With the help of the water migration model, we can deeply understand the laws of water migration, accurately control the water content, and ensure that the soil maintains stable performance in different environments. In actual construction, the water content of high liquid limit clay is always controlled within ±3% of the liquid limit through this system, effectively avoiding cracking and "spring soil" problems. For example, in dry weather, the water content of the soil returns to an appropriate range within 4 hours after the automatic sprinkler is activated.

[0048] S5. Composite compaction: Use a vibratory roller for initial compaction, reinforce the groove edges with an impact rammer, crush the surface layer after each set number of filling layers, and repeat the composite compaction operation until the designed backfill elevation is reached.

[0049] Specifically, the initial compaction of the vibratory roller rearranges the soil particles and fills the pores through vibration, thereby increasing the density of the soil and preliminarily compacting the backfill soil. The edges of the grooves are reinforced with impact rammers. Because the edges of the grooves are weak, the high-energy impact of the impact rammer can make the edge soil denser, enhance the connection strength between the grooves and the surrounding soil, and strengthen the interlocking effect. The surface layer is broken after each set number of filling layers, which can break the compacted layer, increase the contact area and friction between the upper and lower layers of soil, and better combine the subsequent filling soil with the compacted soil, thereby improving the integrity and stability of the backfill. Repeat the composite compaction operation many times to gradually increase the density of the backfill soil until it meets the design requirements. According to testing, the compaction degree of each layer reached more than 95%. After the groove edges were reinforced with impact rammers, the compaction degree reached an average of 97%, which was about 5% higher than the area where the groove interlocking process was not used.

[0050] In this embodiment, in step S3, during the interlocking and alternating filling process, the formula for calculating the amount of water required to be added when the high liquid limit clay filler is wet is:

[0051] m water =m soil ×(w t -w 0 )

[0052] In the formula, m water is the amount of water to be added, m soil is the mass of high liquid limit clay, w t is the target moisture content, w0 is the initial water content.

[0053] Specifically, the formula for calculating the amount of water required to wet the high liquid limit clay filler is based on the principle of conservation of mass. t The amount of water to be added depends on the current initial water content w 0 and clay mass m soil . Accurately calculate the amount of water to be added to avoid adding too much or too little water. Adding too much water will make the soil too wet and difficult to compact, while adding too little water will make the soil dry, which is not conducive to compaction. Accurately controlling the amount of water can ensure that high liquid limit clay is compacted at the optimal moisture content state and improve the compaction effect.

[0054] In this embodiment, in step S3, during the interlocking and alternating filling process, the stress state of the soil is changed by the interlocking structure of the grooves, and the shear strength of the interlocking structure of the grooves formed by the difference in compressibility of different soils is:

[0055]

[0056] In the formula, τ is the shear strength, c is the cohesion, σ is the normal stress, is the internal friction angle.

[0057] Specifically, the groove interlocking structure changes the internal structure of the soil, increasing the soil cohesion c and internal friction angle During the compaction process, different soil types interlock with each other, increasing the connection between soil particles, which is manifested as increased cohesion; the grooves and interlocking structures make the soil particles bite more tightly, enhancing the ability to resist sliding, that is, the internal friction angle increases. According to the shear strength formula, c and When it increases, the shear strength τ of the soil increases, effectively suppressing the expansion of lateral cracks in the soil and improving the integrity and stability of the backfill soil. In actual engineering, the overall settlement of the area using this process is reduced by about 50% compared with the traditional process, verifying the significant effect of the groove interlocking structure on controlling settlement.

[0058] In this embodiment, in step S4, during the dynamic moisture control process, the moisture migration model formula established is:

[0059]

[0060] Where q is the water flux, D is the soil water diffusivity, θ is the volumetric water content, and z is the depth coordinate.

[0061] Specifically, the water migration model describes the migration law of water in the soil. The water flux q represents the amount of water passing through a unit area per unit time, and the soil water diffusion rate D and the rate of change of volume water content along the depth direction. Soil water diffusion rate D reflects the ease of water diffusion in the soil, and the D value varies with soil texture and structure. When the water content is high, it migrates from the area with high water content to the area with low water content, and the migration rate is determined by the formula. This water migration model can quantify the water migration process, provide a theoretical basis for precise water control, determine the spraying or drainage operation, and maintain the appropriate water distribution of the backfill soil. For example, in the rainy season, the water migration model can accurately determine the direction and rate of water migration, drain water in time, and ensure the stability of soil moisture content.

[0062] See also Figure 2 In a possible embodiment, in step S3, during the interlocking and alternating filling process, the high liquid limit clay mixed with the backfill on the ground line 1 after the base treatment is completed is used by the excavation equipment to perform the groove operation in the filling area, and the groove depth is adapted to the thickness of the filling area to form an effective embedded structure with the subsequent filling clay.

[0063] Specifically, the groove depth is adapted to the thickness of the filling area, so that the groove and the subsequent filling clay are fully in contact and embedded with each other. During the compaction process, the high liquid limit clay and clay form a more stable embedded structure, increasing the friction and bite force between layers, similar to the mortise and tenon structure, effectively resisting external forces, preventing interlayer sliding, enhancing the integrity and stability of the soil, and improving the bearing capacity of the backfill structure. In practical applications, this effective embedded structure can make the soil deform less when it is subjected to a large load, ensuring the long-term stability of the project.

[0064] In a possible embodiment, in step S3 , during the groove interlocking alternating filling process, the unmodified high liquid limit clay completely fills the groove area 3 , and forms a continuous and dense clay interlocking area 4 on the surface of the groove area 3 .

[0065] Specifically, the unmodified high liquid limit clay completely fills the groove area 3 to ensure the integrity of the soil at the grooved part and avoid voids or weak points. A continuous and dense clay interlocking area 4 is formed on the surface, which makes the backfill soil more connected and integrated in the horizontal and vertical directions. This structure can effectively transfer stress, reduce stress concentration, and improve soil stability and deformation resistance. Under the action of long-term external forces, the continuous and dense interlocking area can prevent local damage to the soil and extend the service life of the project.

[0066] In a possible embodiment, in step S4, during the dynamic moisture control process, the nozzles of the atomizing spray system 5 are optimally arranged based on the geometric features of the backfill area to achieve uniform coverage of the backfill area and the clay interlocking area 4 after the high liquid limit clay is mixed by the water mist 6.

[0067] Specifically, different backfill areas have different geometric shapes and sizes. Based on their characteristics, the nozzle layout is optimized to ensure that the water mist 6 is evenly sprayed to the area that needs to be moistened. Uniform coverage ensures that the filling area after high liquid limit clay mixing and the clay interlocking area 4 are properly replenished with water to avoid local over-wetting or over-drying. Maintaining the moisture balance of the soil, ensuring the compaction effect and stability, making the moisture content of the backfill soil uniform and consistent, and improving the quality of the project.

[0068] In a possible embodiment, step S4, the dynamic moisture control process, also includes laying geotextiles along the top surface and slope of the backfill structure, and building a distributed monitoring network in combination with the Internet of Things humidity sensor 7 to collect moisture content data of backfill soil at different spatial locations.

[0069] Specifically, geotextiles are laid along the top surface and slope of the backfill structure to retain water and protect the humidity sensor. The IoT humidity sensor 7 builds a distributed monitoring network, which can obtain real-time backfill soil moisture content data at different spatial locations. Since the moisture changes at different locations of the backfill soil are different, distributed monitoring can fully understand the moisture distribution, provide a basis for accurately determining the water replenishment or drainage area, and realize the refined management of the moisture content of the backfill soil.

[0070] In a possible embodiment, in step S5, during the composite compaction process, an impact rammer is used to reinforce and compact the edge of the grooved area 3 to improve the interface bonding strength and density between the grooved area 3 and the surrounding soil.

[0071] Specifically, the edge of the grooved area 3 is a weak part of the backfill structure because the soil structure is loose due to the grooved operation. The impact force of the rammer is large, and the reinforcement and compaction of the edge of the grooved area 3 can make the edge soil particles closely arranged, fill the pores, and improve the density. At the same time, the impact force promotes the fusion of the edge soil with the surrounding soil, increases the interface contact area and adhesion, and improves the interface bonding strength. Strengthen the connection between the grooved area 3 and the surrounding soil to prevent the grooved edge from loosening and falling off during use, and ensure the stability and integrity of the backfill. In actual testing, after the grooved edge was reinforced by the impact rammer, the compaction degree increased by about 2% on average, which effectively enhanced the stability of the area.

[0072] In a possible embodiment, after each layer of groove interlocking is alternately filled, a combination of non-destructive testing and sampling testing is used to evaluate the bonding quality of the groove area 3 and the clay interlocking area 4.

[0073] Specifically, nondestructive testing can detect the internal structure of the groove area 3 and the clay interlocking area 4 without destroying the structure, such as using ultrasound and ground penetrating radar to detect whether there are defects such as cavities and cracks. Sampling testing selects some samples for detailed physical and mechanical property testing, such as compaction, shear strength and other indicators. The combination of the two testing methods can comprehensively and accurately evaluate the bonding quality. Timely discover bonding quality problems, such as loose bonding and insufficient strength, so that measures can be taken to repair and improve, ensure that the construction quality of each layer meets the requirements, and ensure the quality and safety of the backfill project.

[0074] In order to verify the actual effect of the non-improved high liquid limit clay backfill maintenance construction method of the present invention, a field test was carried out. The test site was selected in an area with representative geological conditions and a wide distribution of high liquid limit clay. The test data and analysis are as follows:

[0075] Compactness: The compactness of each filling layer was strictly tested using the ring knife method. In the test area, after the composite compaction process, the compaction of each filling layer reached more than 95%, fully meeting the design requirements. Among them, the compaction of the groove edge after impact tamping reinforcement was as high as 97% on average. Compared with the area where the groove interlocking process was not used, the compaction was significantly improved by about 5%. This clearly shows that the synergy between the groove interlocking process and the composite compaction process effectively improved the compaction of the soil and enhanced the density of the soil.

[0076] Moisture content control: With the help of dynamic moisture control, the moisture content of high liquid limit clay is always accurately controlled within the range of ±3% of the liquid limit. In dry weather, after the automatic sprinkler is activated, the soil moisture content quickly returns to the appropriate range within 4 hours, successfully avoiding the cracking problem caused by rapid evaporation of water. In the rainy season, the drainage system operates efficiently and can promptly remove excess water to ensure the stability of soil moisture content, effectively solving the construction problems caused by the large fluctuation of moisture content of high liquid limit clay.

[0077] Settlement observation: Multiple settlement observation points were set up in the test area, and continuous settlement observation of the backfill soil was carried out for 6 months. The results showed that the overall settlement in the area using this construction method was only 5cm on average. Compared with the traditional layered rolling process, the settlement was reduced by about 50%. This fully verifies the excellent effect of the groove interlocking process and dynamic maintenance system in controlling settlement, which greatly improves the stability and safety of the project.

[0078] Shear strength: According to the on-site direct shear test, the shear strength of the soil using the groove interlocking process is about 30% higher than that of the traditional layered rolling soil. The interlocking structure of the grooves changes the stress state of the soil and significantly increases the cohesion c and internal friction angle. This effectively inhibits the expansion of transverse cracks and greatly enhances soil stability.

[0079] Cost-effectiveness: Compared with the traditional chemical improvement method, the construction method of the present invention has achieved remarkable results in cost control. Since it avoids the use of a large amount of chemical improvers and greatly reduces the amount of earthwork abandoned, the cost is reduced by 40%-60%, and the amount of abandoned earthwork is reduced by 80%, which greatly reduces the cost of earthwork transportation and treatment, showing significant economic benefits.

[0080] Long-term stability: In the 12-month follow-up monitoring after the end of the test, no obvious quality problems occurred in the area where this construction method was used. The compaction degree and water content of the soil remained stable, and the settlement did not increase significantly, proving that the invention not only has a significant effect in the construction stage, but also can ensure the long-term stability of the project and effectively reduce the later maintenance costs.

[0081] The above test data fully prove that the non-improved high liquid limit clay backfill maintenance construction method of the present invention has remarkable results in improving compaction, accurately controlling water content, effectively suppressing settlement, enhancing shear strength and greatly reducing costs, etc., providing a practical, efficient and reliable solution for high liquid limit clay backfill construction.

[0082] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A non-improved high liquid limit clay backfill maintenance construction method, characterized in that: The steps include: Preparation before construction: determine the source and location of backfill earthwork, screen and process earthwork materials, organize construction teams, prepare and debug construction equipment, and formulate safety measures for the construction site; Backfill base treatment: clean up debris and accumulated water on the backfill base, level and compact the backfill base, and treat special areas and soft soil foundations in the backfill base, including paddy fields, reservoirs, and fish ponds; Grooving interlocking alternating filling: Wet high liquid limit clay filler, fill and compact it, then groove it, then cover and fill it with clay and compact it, using the difference in compressibility of different soils to form an interlocking effect; Dynamic moisture control: Control the initial moisture content of high liquid limit clay, monitor the moisture content of backfill soil in real time, spray or drain according to the monitored moisture content of backfill soil, and control the moisture with the help of moisture migration model; Composite compaction: Use a vibratory roller for initial compaction, reinforce the groove edges with an impact rammer, crush the surface layer after each set number of filling layers, and repeat the composite compaction operation until the designed backfill elevation is reached.

2. The non-improved high liquid limit clay backfill maintenance construction method according to claim 1, characterized in that: The formula for calculating the amount of water required to wet the high liquid limit clay filler during the interlocking groove filling process is: m water =m soil ×(w t -w0) In the formula, m water is the amount of water to be added, m soil is the mass of high liquid limit clay, w t is the target moisture content, w0 is the initial moisture content.

3. The non-improved high liquid limit clay backfill maintenance construction method according to claim 1, characterized in that: During the interlocking filling process, the stress state of the soil is changed by the interlocking structure. The shear strength of the interlocking structure formed by the difference in compressibility of different soils is: In the formula, τ is the shear strength, c is the cohesion, σ is the normal stress, is the internal friction angle.

4. The non-improved high liquid limit clay backfill maintenance construction method according to claim 1, characterized in that: In the process of dynamic moisture regulation, the established moisture migration model formula is: Where q is the water flux, D is the soil water diffusivity, θ is the volumetric water content, and z is the depth coordinate.

5. The non-improved high liquid limit clay backfill maintenance construction method according to claim 1, characterized in that: During the interlocking and alternating filling process, after the base treatment is completed, the high liquid limit clay on the backfill ground line (1) is mixed with the filling area (2) to perform the groove operation. The groove depth is adapted to the thickness of the filling area to form an effective embedded structure with the subsequent filling clay.

6. The non-improved high liquid limit clay backfill maintenance construction method according to claim 5, characterized in that: During the interlocking alternating filling process, the unmodified high liquid limit clay completely fills the groove area (3) and forms a continuous and dense clay interlocking area (4) on the surface of the groove area (3).

7. The non-improved high liquid limit clay backfill maintenance construction method according to claim 1, characterized in that: During the dynamic moisture control process, the nozzles of the atomizing spray system (5) are optimally arranged based on the geometric features of the backfill area, so as to achieve uniform coverage of the backfill area (2) and the clay interlocking area (4) by the water mist (6).

8. The non-improved high liquid limit clay backfill maintenance construction method according to claim 1, characterized in that: The dynamic moisture control process also includes laying geotextiles along the top surface and slope of the backfill structure, and building a distributed monitoring network in combination with an Internet of Things humidity sensor (7) to collect moisture content data of the backfill soil at different spatial locations.

9. The non-improved high liquid limit clay backfill maintenance construction method according to claim 1, characterized in that: During the composite compaction process, an impact rammer is used to reinforce and compact the edge of the grooved area (3), thereby improving the interface bonding strength and density between the grooved area (3) and the surrounding soil.

10. The non-improved high liquid limit clay backfill maintenance construction method according to claim 1, characterized in that: After each layer of groove interlocking is completed, the bonding quality of the groove area (3) and the clay interlocking area (4) is evaluated by combining non-destructive testing and sampling testing.

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