A hill piling settlement control structure and construction method

Abstract

The application provides a mountain piling settlement control structure and a construction method thereof, which comprises a foundation reinforcement layer, a filling body, a drainage and anti-seepage system and a monitoring and early warning device; the foundation reinforcement layer is laid on an original foundation, used for improving the bearing capacity of the foundation and reducing the foundation settlement and the surrounding ground surface deformation; the filling body is covered on the top of the foundation reinforcement layer, and a layered compaction and reinforced enhancement process is adopted to improve the integrity and compression resistance of the filling body; the drainage and anti-seepage system is arranged in the interior and the surrounding area of the foundation reinforcement layer and the filling body, used for guiding and draining the surface water and the underground water, preventing the water from infiltrating and softening the filling body and the foundation; the monitoring and early warning device is arranged in the interior and the surrounding area of the foundation reinforcement layer and the filling body, used for monitoring the mountain piling settlement, the horizontal displacement and the pore water pressure in real time, issuing early warning and guiding adjustment in time; the precise control of the mountain piling settlement is realized, the safety and stability of the mountain piling project are ensured, the resource utilization of the construction waste is realized, and the engineering cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of artificial hill construction technology, specifically relating to a hill settlement control structure and construction method, applicable to various artificial hill construction projects, landscape hill construction, ecological restoration hill construction of abandoned sites, etc., especially applicable to hill settlement control under complex geological conditions such as soft soil and coastal fill. Background Technology

[0002] With the advancement of urbanization, urban land resources are becoming increasingly scarce, and artificial hill construction is being used more and more widely in fields such as landscape construction, airport construction, new town expansion, and ecological restoration of abandoned mines. Artificial hills create undulating terrain by filling soil and piling up rocks, meeting the needs of urban landscape creation, land use optimization, and ecological restoration. However, during the construction and operation of artificial hill projects, settlement has always been a key bottleneck restricting the quality and safety of the projects.

[0003] In existing hill-building projects, settlement problems mainly manifest as excessive overall settlement, significant uneven settlement, and prolonged post-construction settlement. The main causes include: First, inadequate foundation treatment, especially in complex geological areas such as soft soil and fill. Soft soil (silty clay, silty mud) has a natural moisture content of 35%-60%, a natural void ratio of 1.0-1.5, a compression modulus of 3-8 MPa, and a bearing capacity characteristic value of 50-120 kPa. Fill (coastal / river fill) has a natural moisture content of 25%-45%, a natural void ratio of 0.8-1.2, a compression modulus of 5-10 MPa, and a bearing capacity characteristic value of... The characteristic values ​​are 80-150 kPa. Both types of foundations have low bearing capacity and high compressibility, making them prone to significant settlement under the load of the mound. Secondly, the filling process is unreasonable, with one-time loading and incomplete layered compaction, resulting in insufficient density of the fill and significant consolidation deformation in the later stage. Thirdly, the drainage and seepage prevention measures are inadequate, with rainwater infiltration causing softening and reduced strength of the fill, and groundwater accumulation exacerbating foundation settlement, which may also trigger secondary disasters such as slope landslides. Fourthly, the lack of an effective real-time monitoring and early warning mechanism makes it impossible to grasp the settlement change pattern in a timely manner and take preventive measures in advance, leading to the expansion of settlement problems.

[0004] Currently, existing settlement control technologies for manholes mostly employ single methods such as foundation reinforcement or layered compaction, lacking a systematic solution and failing to simultaneously address the synergistic effects of improving foundation bearing capacity, consolidating the fill, drainage and seepage prevention, and real-time monitoring. For example, some technologies only reinforce the foundation, neglecting the impact of the fill's own compression deformation and rainwater infiltration; others focus on optimizing the filling process but lack effective foundation treatment measures, leading to foundation settlement becoming a major hidden danger; still others lack a comprehensive monitoring and early warning system, failing to detect settlement anomalies in a timely manner and hindering precise settlement control. Furthermore, existing technologies often use fresh fill material for manholes, neglecting the synergistic utilization of construction waste and engineering spoil, increasing project costs and wasting resources.

[0005] Therefore, in view of the shortcomings of existing technologies, there is an urgent need for a reasonable structure, convenient construction and effective control method for the settlement of manholes, which can realize the integrated and coordinated control of foundation reinforcement, layered filling, drainage and seepage prevention and monitoring and early warning, effectively reduce the settlement of manholes, improve the safety and durability of the project, and realize the resource utilization of construction waste, taking into account both environmental protection and economy. Summary of the Invention

[0006] This invention aims to provide a settlement control structure and construction method for manholes. By constructing an integrated system of "foundation reinforcement - layered filling - drainage and seepage prevention - monitoring and early warning", it solves the problems of poor settlement control effect, insufficient foundation bearing capacity, large deformation of surrounding surface, slow consolidation of filling body, rainwater infiltration and softening, and untimely settlement monitoring in existing technologies. It achieves precise control of manhole settlement, ensures the safety and stability of manhole projects, and realizes the resource utilization of construction waste, reduces project costs, and improves the environmental benefits of the project.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A settlement control structure for a hill is provided, comprising a foundation reinforcement layer, a backfill, a drainage and seepage prevention system, and a monitoring and early warning device.

[0009] The foundation reinforcement layer is laid on top of the original foundation to improve the bearing capacity of the foundation and reduce foundation settlement and surrounding surface deformation. The foundation reinforcement layer includes a support pile group, a cushion layer, and a leveling layer. The support pile group is formed by alternating long and short piles, with the bottom of the long piles embedded at least 1m into the bearing layer of the original foundation. The cushion layer is laid on top of the support pile group, and the top elevation of the cushion layer is higher than that of the support pile group. The cushion layer includes several layers of graded crushed stone and several layers of geogrid I. A layer of geogrid I is placed between adjacent graded crushed stone layers. After each layer of graded crushed stone is laid, it is compacted. The leveling layer covers the top of the cushion layer.

[0010] The fill material covers the top of the foundation reinforcement layer and adopts a layered compaction and reinforcement process to improve the integrity and compressibility of the fill material.

[0011] The drainage and seepage prevention system is installed inside and around the foundation reinforcement layer and the fill body to guide surface water and groundwater, preventing water infiltration and softening of the fill body and foundation. The drainage and seepage prevention system includes a slope seepage prevention structure, a slope toe drainage structure, and an underground drainage structure, forming a comprehensive drainage and seepage prevention system. The slope seepage prevention structure is installed on the side of the fill layer and on the top surface of the uppermost fill layer. The slope seepage prevention structure is a capillary-retaining cover layer and includes a water-holding layer and a drainage layer arranged sequentially from top to bottom. The underground drainage structure includes a drainage pipe network laid at the bottom of the mattress layer and a drainage pipe network laid between adjacent fill layers. The drainage pipe networks of each layer are connected to the slope toe drainage structure.

[0012] The monitoring and early warning device is installed in the foundation reinforcement layer, inside and around the filling body, and is used to monitor the settlement, horizontal displacement and pore water pressure of the hill in real time, and issue early warnings and guide adjustments in a timely manner.

[0013] Preferably, in the above-mentioned hill settlement control structure, the length of the short pile is 1 / 2 to 2 / 3 of that of the long pile, and the spacing ratio of the long pile to the short pile is 1:1.2 to 1.5.

[0014] Preferably, in the above-mentioned hill settlement control structure, the graded crushed stone layer uses graded crushed stone with a particle size of 15mm to 30mm; the thickness of the cushion layer is not less than 300mm, and the cushion layer is composed of graded crushed stone with a particle size of 15mm to 30mm and geogrid I. The graded crushed stone contains no more than 3% of the total weight of crushed stone fragments, and the compaction degree is not less than 0.9. The cushion layer can effectively disperse the pile top load, adjust the pile-soil stress ratio, avoid the concentration of stress on the pile body, and at the same time play a certain role in drainage.

[0015] Preferably, in the above-mentioned hill settlement control structure, the leveling layer is made of plain concrete with a thickness of 80-120mm, and the top surface is flush with the design elevation to ensure the flatness of subsequent layered filling and provide a uniform support surface for the filling body.

[0016] Preferably, in the above-mentioned hill settlement control structure, the filling body is formed by rolling several filling layers one by one. Each filling layer includes several filling unit layers and several layers of geogrid II. After each filling unit layer is laid, it is rolled. Geogrid II is laid between adjacent filling unit layers. The thickness of each filling layer is 1-4m, the compaction coefficient λ≥0.92, and the compression modulus Es≥10MPa to ensure the density of the filling body and reduce the later consolidation settlement. The filling unit layer adopts alternating layers of engineering waste soil and recycled fine aggregate to make full use of the engineering characteristics of construction waste and realize resource utilization. At the same time, the good drainage performance of recycled fine aggregate can promote the drainage consolidation of the filling body. The compaction width of the bottom filling layer is not less than the design width, and the compaction degree gradually decreases by no more than 5% from top to bottom to adapt to the load distribution law and improve the overall stability.

[0017] Preferably, in the above-mentioned hill settlement control structure, the slope toe drainage structure includes drainage blind pipes and a counter-pressure layer arranged around the slope toe. The blind pipes have a diameter of 90mm to 180mm, are made of fibrous plastic, are spaced 1.5-2.5m apart, are arranged at an incline, have a slope of not less than 3‰, and extend to the external drainage system of the hill. The filter layer is filled with large-diameter waste stone and has a thickness of not less than 1m.

[0018] Preferably, in the above-mentioned hill settlement control structure, the water-holding layer is filled with pre-screened slag soil with a thickness of 0.4-0.6m, and the drainage layer is filled with recycled fine aggregate with a thickness of 0.2-0.4m. The interface between the two has a capillary repression effect due to the different water-holding properties, which can effectively block rainwater infiltration and store some water for the growth of vegetation on the slope, thus achieving both seepage prevention and ecological considerations. The compaction degree of both the water-holding layer and the drainage layer of the slope seepage prevention structure is not less than 80%, and the periphery of the drainage layer extends upward to form a surround of the water-holding layer with an extension height of not less than 250mm, thereby enhancing the seepage prevention effect.

[0019] Preferably, in the above-mentioned hill settlement control structure, the monitoring and early warning device includes settlement monitoring points, horizontal displacement monitoring points, pore water pressure monitoring points, and a data acquisition terminal to realize real-time monitoring, data acquisition, and early warning of hill settlement, horizontal displacement, and pore water pressure. The settlement monitoring points include hill settlement monitoring points, original foundation surface settlement monitoring points, and original foundation soil layered settlement monitoring points. The hill settlement monitoring points are arranged in a grid pattern with a spacing of 5-10m, located on the sides and inside of each fill layer, for monitoring overall settlement and differential settlement. The original foundation surface settlement monitoring points are arranged around the perimeter of the slope toe. The original foundation soil layered settlement monitoring points are arranged around the perimeter of the slope toe at a certain soil layer depth. The horizontal displacement monitoring points include original foundation surface settlement monitoring points, horizontal displacement ... The system includes deep foundation soil horizontal displacement monitoring points and edge pile horizontal displacement monitoring points. The deep foundation soil horizontal displacement monitoring points are positioned on the surface of the slope toe of the fill layer at intervals of 3-5m to monitor the lateral displacement of the fill layer and prevent landslides. The edge pile horizontal displacement monitoring points are arranged around the perimeter of the slope toe. Pore water pressure monitoring points are embedded at the bottom of each fill layer to monitor changes in pore water pressure and guide adjustments to drainage measures. Settlement monitoring points, horizontal displacement monitoring points, and pore water pressure monitoring points are all wirelessly connected to a data acquisition terminal. Settlement warning values ​​are set to no more than 300mm, and differential settlement warning values ​​are set to no more than 50mm. When the monitoring data approaches the warning values, the data acquisition terminal promptly issues a warning signal to facilitate preventative measures by staff.

[0020] Preferably, in the above-mentioned hill settlement control structure, the long piles in the support pile group are cement mixing piles, which use PO42.5 grade ordinary Portland cement with a single-axis admixture of not less than 100 kg / m, a mud-cement ratio of 0.50 to 0.60, and four times of grouting and four times of mixing. The grouting stop surface is 50 cm higher than the design elevation of the pile top to ensure the strength of the pile body and the construction quality. The short piles are pressure-grown plain concrete piles with a pile diameter deviation of not more than 4% of the design pile diameter, a pile position deviation of not more than 50 mm, and a verticality deviation of not more than 1% of the design verticality deviation to ensure that the pile body is evenly arranged and under stable stress.

[0021] This invention also discloses a construction method for the settlement control structure of the manhole as described above, comprising the following steps:

[0022] Step S1: Construct the support pile group and slope toe drainage structure:

[0023] Clear debris, weeds, and loose soil from the original foundation surface and level the surface. According to the design plan, lay long and short piles at predetermined intervals on the original foundation to form a support pile group. After construction, perform pile curing to ensure the pile strength meets design requirements. Install a slope toe drainage structure and set up settlement monitoring points and horizontal displacement monitoring points at the slope toe. Begin monitoring the surface settlement at the slope toe through the settlement monitoring points; begin monitoring the horizontal displacement at the slope toe through the horizontal displacement monitoring points.

[0024] Step S2: Construct the drainage pipe network, bedding layer, and leveling layer.

[0025] After the support pile group is cured, a drainage pipe network is laid and connected to the slope toe drainage structure. Then, a mattress layer is laid, which includes several layers of graded crushed stone and several layers of geogrid I. A layer of geogrid I is placed between adjacent graded crushed stone layers. After each layer of graded crushed stone is laid, it is compacted. A leveling layer is poured on top of the mattress layer and compacted using a plate vibrator to ensure that the top surface of the leveling layer is flat and flush with the design elevation. Pore water pressure monitoring points are embedded inside the mattress layer. Changes in pore water pressure inside the mattress layer are monitored through these monitoring points.

[0026] Step S3, Filling construction:

[0027] The fill body is formed by rolling several fill layers one by one. Each fill layer includes several fill unit layers and several layers of geogrid II. After each fill unit layer is laid, it is rolled. Geogrid II is laid between adjacent fill unit layers. During construction, after each fill unit layer is laid, it is rolled, and then geogrid II is laid. Then another fill unit layer is laid and the cycle continues until the fill layer reaches the design height. The thickness of each fill layer is 1-4m, the compaction coefficient λ≥0.92, and the compression modulus Es≥10MPa to ensure the density of the fill body and reduce the later consolidation settlement. Geogrid II can enhance the integrity and shear resistance of the fill body, suppress the lateral deformation and stratification slip of the fill body, and reduce differential settlement. The filling unit layer adopts alternating layers of engineering waste soil and recycled fine aggregate, making full use of the engineering characteristics of construction waste to achieve resource utilization. At the same time, the good drainage performance of recycled fine aggregate can promote drainage consolidation of the filling body. The compaction width of the bottom filling layer is not less than the design width, and the compaction degree gradually decreases by no more than 5% from top to bottom to adapt to the load distribution pattern and improve the overall stability. A drainage pipe network is laid between adjacent filling layers and connected to the slope toe drainage structure. A slope seepage prevention structure is set around each fill layer. The slope seepage prevention structure includes a water-holding layer and a drainage layer arranged sequentially from top to bottom. The water-holding layer is filled with pre-screened slag and has a thickness of 0.4-0.6m. The drainage layer is filled with recycled fine aggregate and has a thickness of 0.2-0.4m. The interface between the two layers produces a capillary retraction effect due to their different water-holding properties, which can effectively block rainwater infiltration and store some water for the growth of vegetation on the slope, thus achieving both seepage prevention and ecological considerations. The compaction degree of both the water-holding layer and the drainage layer of the slope seepage prevention structure is not less than 80%. The periphery of the drainage layer extends upward to form a ring around the water-holding layer, with an extension height of not less than 250mm, to enhance the seepage prevention effect. A pore water pressure monitoring point is embedded at the bottom of each fill layer to monitor the changes in pore water pressure inside each fill layer. Settlement monitoring points and horizontal displacement monitoring points are set up at the design locations on the sides, inside, and top of the fill layer. Settlement monitoring points are used to monitor the settlement on the sides, inside, and top of the fill layer. Horizontal displacement monitoring points are used to monitor the horizontal displacement on the sides, inside, and top of the fill layer.

[0028] Step S4, Debugging of monitoring and early warning devices:

[0029] Wirelessly connect all monitoring points to the data acquisition terminal, debug the monitoring equipment, and ensure stable data transmission; set settlement warning values ​​and differential settlement warning values, complete the debugging of the monitoring and warning system, and realize real-time monitoring of settlement and related parameters.

[0030] Step S5: Post-maintenance and monitoring adjustments.

[0031] Preferably, in the above-mentioned construction method for the settlement control structure of the hill, the post-construction maintenance and monitoring adjustment in step S5 includes: after the hill is completed, the slope is watered to prevent cracking, and the maintenance time is not less than 6 months; during the maintenance period, the data acquisition terminal collects monitoring data every 24 hours to analyze the settlement change pattern; if the settlement amount approaches the warning value, settlement control measures are taken in time until the settlement stabilizes. The settlement control measures include driving additional support piles, adding drainage channels, slowing down the loading speed, and reinforcing the slope; after the settlement stabilizes, the monitoring data collection cycle is extended to once every 72 hours, and the continuous monitoring time is not less than 1 year to ensure that the post-construction settlement is controlled within the design range.

[0032] Preferably, in the above-mentioned construction method for the settlement control structure of the hill, before step S1, engineering survey and scheme design are also included:

[0033] First, determine the planar scope of the land for the hill construction, the design height of the hill, and the slope ratio. Conduct geotechnical engineering investigation to ascertain the lithology, distribution thickness, and physical and mechanical parameters of the original foundation. Use the discrete element method combined with field tests to verify the foundation bearing capacity and settlement, and determine the specific structural parameters and construction technology of the foundation reinforcement layer, fill body, drainage and seepage prevention system, and monitoring and early warning device. At the same time, perform slope stability calculations, considering the slope safety level as a first-class permanent slope, ensuring that the slope stability coefficient is not less than 1.35, and avoiding the mutual influence of slope landslides and settlement.

[0034] As can be seen from the above-disclosed technical solutions, the beneficial effects of the present invention compared with the prior art are as follows:

[0035] I. An integrated collaborative control system of "foundation reinforcement - layered filling - drainage and seepage prevention - monitoring and early warning" has been constructed. From foundation treatment, filling construction, waterproofing and drainage to real-time monitoring, it comprehensively prevents and controls the settlement of the hill. It solves the problem of poor single control effect of existing technologies. It can effectively control the post-construction settlement of the hill to no more than 300mm and the differential settlement to no more than 50mm, thereby improving the safety and durability of the hill project.

[0036] Second, the foundation reinforcement layer adopts a composite structure of long and short piles combined with a cushion layer to achieve coordinated reinforcement of the deep and shallow foundations, effectively improve the bearing capacity of the foundation, disperse the load of the hill, reduce uneven settlement of the foundation, adapt to complex geological conditions such as soft soil and fill soil, and solve the settlement hazards caused by insufficient foundation bearing capacity.

[0037] Third, the filling body adopts a graded loading and layered compaction process, embedding geogrid II to enhance the integrity. At the same time, it adopts alternating layers of engineering waste soil and recycled fine aggregate, which not only improves the compression and sliding resistance of the filling body, but also realizes the resource utilization of construction waste, reduces the project cost, and combines environmental protection and economy. It can comprehensively absorb a large amount of engineering waste soil and recycled aggregate.

[0038] IV. The drainage and seepage prevention layer adopts a capillary-retaining cover layer combined with slope toe drainage and underground drainage structure to achieve the zoned drainage of surface water and groundwater, effectively blocking rainwater infiltration, lowering the groundwater level, reducing the softening effect of water on the fill and foundation, while taking into account the ecological maintenance of the slope, avoiding the aggravation of settlement and slope landslides caused by water accumulation.

[0039] Fifth, the monitoring and early warning layer enables real-time monitoring and early warning of settlement, horizontal displacement, and pore water pressure. It can promptly grasp the changing patterns of settlement of the hill, detect settlement anomalies in advance, facilitate timely prevention and control measures by staff, prevent the settlement problem from escalating, and achieve precise control of settlement.

[0040] VI. The construction process is convenient, the steps are clear, and the connection between each process is smooth. It does not require complicated large-scale equipment, has high construction efficiency, and can be adapted to pile-up projects of different scales and geological conditions. It is especially suitable for pile-up construction in complex areas such as coastal fill, soft soil, and abandoned mines, and has a wide range of application prospects. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a settlement control structure for a manhole in an embodiment of the present invention (and also a schematic diagram of the structure after step 3 of the construction method of the settlement control structure for a manhole in an embodiment of the present invention is completed).

[0042] Figure 2 This is an embodiment of the present invention. Figure 1 Enlarged schematic diagram of part A.

[0043] Figure 3 This is an embodiment of the present invention. Figure 1 Enlarged schematic diagram of part B.

[0044] Figure 4 This is a schematic diagram of the foundation reinforcement layer in one embodiment of the present invention.

[0045] Figure 5 This is a schematic diagram of the structure of the filling body, mattress layer and leveling layer in one embodiment of the present invention.

[0046] Figure 6 This is a schematic diagram showing the distribution of monitoring points in one embodiment of the present invention.

[0047] Figure 7 This is a schematic diagram of step 1 of a construction method for a settlement control structure for a hill according to an embodiment of the present invention.

[0048] Figure 8 This is a schematic diagram of step 2 of a construction method for a hill settlement control structure according to an embodiment of the present invention.

[0049] Figure 9This is a schematic diagram of the structure after the first filling layer is constructed in step 3 of the construction method of the settlement control structure for a hill according to an embodiment of the present invention.

[0050] Figure 10 This is a schematic diagram of the structure after the second filling layer is constructed in step 3 of the construction method of the settlement control structure for a hill according to an embodiment of the present invention.

[0051] Figure 11 This is a schematic diagram of a settlement control structure for a hill according to another embodiment of the present invention.

[0052] In the diagram: 1-Long pile, 2-Short pile, 3-Cushion layer, 3.1-Graded crushed stone layer, 3.2-Geogrid I, 4-Leveling layer, 5-Fill layer, 5.0-Top of fill layer, 5.1-Fill unit layer, 5.2-Geogrid II, 6-Slope toe drainage structure, 6.1-Blind pipe, 6.2-Filter layer, 7-Slope anti-seepage structure, 7.1-Water-holding layer, 7.2-Drainage layer, 8.1-Drainage pipe network laid at the bottom of cushion layer, 8.2-Drainage pipe network laid between adjacent fill layers, 9-Slope toe, 10-Mountain top. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The technical content and features of the present invention will be described in detail below with reference to the listed embodiments and the accompanying drawings. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention. For ease of description, the terms "upper" and "lower" used below are consistent with the upper and lower directions in the accompanying drawings, but this should not be construed as a limitation of the technical solution of the present invention.

[0054] Example 1

[0055] Please see Figures 1 to 10 This embodiment describes a settlement control structure and construction method for a landscaping hill in a coastal reclaimed land area. The hill is designed to be 36m high with a slope ratio of 1:2.5. The original foundation is a coastal reclaimed soil layer, mainly composed of silty clay mixed with sand, with a thickness of 5-7m. Specific geological parameters are as follows: natural moisture content 32%-40%, natural void ratio 0.95-1.15, compression modulus 7-9MPa, bearing capacity characteristic value 100-140kPa, salt content 1.5%-2.8%, and permeability coefficient 3×10⁻⁻⁻⁶. 6 -8×10⁻ 5 The ground has a density of cm / s, low bearing capacity, high compressibility, and salt corrosion problems. It is necessary to focus on controlling the settlement of the hill and the impact of salt corrosion.

[0056] This embodiment of a hill settlement control structure includes a foundation reinforcement layer, a fill body, a drainage and seepage prevention system, and a monitoring and early warning device. The foundation reinforcement layer is laid on the original foundation to improve the bearing capacity of the foundation and control the deformation of the surrounding surface, thereby reducing foundation settlement. The fill body covers the top of the foundation reinforcement layer and adopts a layered compaction and reinforcement process to improve the integrity and compressibility of the fill body. The drainage and seepage prevention system is set inside and around the foundation reinforcement layer and the fill body to guide and drain surface water and groundwater, preventing water infiltration and softening of the fill body and foundation. The monitoring and early warning device is set inside and around the foundation reinforcement layer and the fill body to monitor the hill settlement, horizontal displacement, and pore water pressure in real time, and to issue early warnings and guide adjustments in a timely manner.

[0057] Preferably, in the above-mentioned settlement control structure for the hill, the foundation reinforcement layer includes a support pile group, a cushion layer 3, and a leveling layer 4. The support pile group is formed by alternating long piles 1 and short piles 2. The bottom of the long piles 1 is embedded at least 1m into the original bearing layer of the foundation to ensure the support stability of the deep foundation. The short piles 2 are 1 / 2 to 2 / 3 the length of the long piles 1 and are used to enhance the bearing capacity of the shallow foundation. The spacing ratio of the long piles 1 to the short piles 2 is 1:1.2 to 1.5 to achieve coordinated reinforcement of the deep and shallow foundations and reduce [burden / damage]. Uneven settlement of the foundation; the cushion layer 3 is laid on top of the support pile group, and the top elevation of the cushion layer 3 is higher than the top elevation of the support pile group. The cushion layer 3 includes several layers of graded crushed stone 3.1 and several layers of geogrid I 3.1. A layer of geogrid I 3.1 is set between adjacent layers of graded crushed stone 3.1. After each layer of graded crushed stone 3.1 is laid, it is compacted. The leveling layer 4 covers the top of the cushion layer 3, thereby forming a composite foundation structure, effectively dispersing the pile load and improving the bearing capacity of the foundation.

[0058] Preferably, in the above-mentioned hill settlement control structure, the graded crushed stone layer 3.1 adopts graded crushed stone with a particle size of 15mm to 30mm; the thickness of the cushion layer 3 is not less than 300mm, and the cushion layer 3 is composed of graded crushed stone with a particle size of 15mm to 30mm and geogrid I 3.1. The graded crushed stone contains no more than 3% of the total weight of crushed stone fragments, and the compaction degree is not less than 0.9. The cushion layer 3 can effectively disperse the pile top load, adjust the pile-soil stress ratio, avoid the pile body stress concentration, and at the same time play a certain role in drainage.

[0059] Preferably, in the above-mentioned hill settlement control structure, the leveling layer 4 is made of plain concrete with a thickness of 80-120mm, and the top surface is flush with the design elevation to ensure the flatness of subsequent layered filling and provide a uniform support surface for the filling body.

[0060] Preferably, in the above-mentioned hill settlement control structure, the filling body is formed by rolling several filling layers 5 one by one. Each filling layer 5 includes several filling unit layers 5.1 and several geogrid II 5.2. After each filling unit layer 5.1 is laid, it is rolled and then the geogrid II 5.2 is laid. Then another filling unit layer 5.1 is laid and the construction cycle begins until the filling layer 5 reaches the design height, that is, the top 5.0 of the filling layer. The thickness of each filling layer 5 can be 1~4m. In this embodiment, the thickness of each filling layer 5 is 3m, the compaction coefficient λ≥0.92, and the compression modulus Es≥10MPa to ensure the density of the filling body and reduce the later consolidation settlement. The two ends of the geogrid II 5.2 are folded back by not less than 3m and the distance from the slope surface is not less than 0.5m. The geogrid II 5.2 can enhance the integrity and shear resistance of the filling body, suppress the lateral deformation and layer slip of the filling body, and reduce differential settlement. The filling unit layer 5.1 adopts alternating layers of engineering waste soil and recycled fine aggregate to make full use of the engineering characteristics of construction waste and realize resource utilization. At the same time, the good drainage performance of recycled fine aggregate can promote the drainage and consolidation of the filling body. The compaction width of the bottom filling layer 5 is not less than the design width, and the compaction degree gradually decreases from top to bottom by no more than 5%, which adapts to the load distribution law and improves the overall stability.

[0061] Preferably, in the above-mentioned hill settlement control structure, the drainage and seepage prevention system includes a slope seepage prevention structure 7, a slope toe drainage structure 6, and an underground drainage structure, forming a comprehensive drainage and seepage prevention system to reduce the adverse effects of water on the hill structure. The slope seepage prevention structure 7 is set on the side of the filling layer 5 and the top surface of the uppermost filling layer 5. The top of the slope seepage prevention structure 7 on the top surface of the uppermost filling layer 5 serves as the mountain top 10. The slope seepage prevention structure 7 is a capillary-retaining type cover layer. The slope seepage prevention structure 7 includes a water-holding layer 7.1 and a drainage layer 7.2 arranged sequentially from top to bottom. The water-holding layer 7.1 is filled with pre-screened slag soil with a thickness of 0.4-0.6m, and the drainage layer 7.2 is filled with recycled fine aggregate with a thickness of 0.2-0.4m. The interface between the two layers produces a capillary-retaining effect due to their different water-holding properties, which can effectively prevent rainwater infiltration and store some water for the growth of vegetation on the slope, thus achieving both seepage prevention and ecological considerations. The compaction degree of both the water-holding layer 7.1 and the drainage layer 7.2 of the slope seepage prevention structure 7 is not less than 80%. The periphery of the drainage layer 7.2 extends upward to form an enclosure of the water-holding layer 7.1, with an extension height of not less than 250mm, thereby enhancing the seepage prevention effect. The slope toe drainage structure 6 includes drainage blind pipes 6.1 and a filter layer 6.2 arranged around the slope toe 9. The filter layer is located inside the blind pipes 6.1. The blind pipes 6.1 have a diameter of 90mm to 180mm and are made of fibrous plastic. They are spaced 1.5-2.5m apart, arranged at an angle with a slope of not less than 3‰, and extend to the external drainage system of the hill. They are used to drain water and salt from the slope surface and underground (especially suitable for coastal reclaimed land areas). The filter layer 6.2 is filled with large-diameter waste stone and has a thickness of not less than 1m. It can enhance the stability of the slope toe 9 and inhibit the settlement and slippage of the slope toe 9. The underground drainage structure includes a drainage pipe network 8.1 laid at the bottom of the cushion layer and a drainage pipe network 8.2 laid between adjacent filling layers 5. The drainage pipe networks of each layer, i.e., all drainage pipe networks, are connected to the slope toe drainage structure 6 to achieve rapid drainage of groundwater, lower the groundwater level, reduce the pore water pressure of the foundation, and promote foundation consolidation.

[0062] Preferably, in the above-mentioned hill settlement control structure, the monitoring and early warning device includes settlement monitoring points, horizontal displacement monitoring points, pore water pressure monitoring points, and a data acquisition terminal to realize real-time monitoring, data acquisition, and early warning of hill settlement, horizontal displacement, and pore water pressure; the settlement monitoring points include hill settlement monitoring points, original foundation surface settlement monitoring points, and original foundation soil layered settlement monitoring points; the hill settlement monitoring points are arranged in a grid pattern with a spacing of 5-10m, and are located on the sides and inside of each filling layer 5 to monitor overall settlement and differential settlement; the original foundation surface settlement monitoring points are arranged around the perimeter of the slope toe 9; the original foundation soil layered settlement monitoring points are arranged around the perimeter of the slope toe 9 at a certain soil layer depth; the horizontal displacement monitoring points include original foundation... The system includes deep soil horizontal displacement monitoring points and edge pile horizontal displacement monitoring points. The deep soil horizontal displacement monitoring points are located on the surface of the soil at the toe of the slope 9 of the fill layer 5, spaced 3-5m apart, to monitor the lateral displacement of the fill layer 5 and prevent landslides. The edge pile horizontal displacement monitoring points are arranged around the perimeter of the slope toe 9. Pore water pressure monitoring points are embedded at the bottom of each fill layer 5 to monitor changes in pore water pressure and guide adjustments to drainage measures. Settlement monitoring points, horizontal displacement monitoring points, and pore water pressure monitoring points are all wirelessly connected to a data acquisition terminal. Settlement warning values ​​are set to no more than 300mm, and differential settlement warning values ​​are set to no more than 50mm. When the monitoring data approaches the warning value, the data acquisition terminal promptly issues a warning signal to facilitate preventative measures by staff.

[0063] Preferably, in the above-mentioned hill settlement control structure, the long pile 1 in the support pile group is a cement mixing pile, which uses PO42.5 grade ordinary Portland cement, with a single-axis admixture of not less than 100 kg / m, a mud-cement ratio of 0.50 to 0.60, and four times of grouting and four times of mixing. The grouting stop surface is 50 cm higher than the design elevation of the pile top to ensure the strength of the pile body and the construction quality. The short pile 2 is a pressure-grown plain concrete pile, with a pile diameter deviation of not more than 4% of the design pile diameter, a pile position deviation of not more than 50 mm, and a verticality deviation of not more than 1% of the design verticality deviation to ensure that the pile body is evenly arranged and under stable stress.

[0064] Please see Figures 1 to 10 This embodiment also discloses a construction method for the settlement control structure of the manhole as described above, including the following steps:

[0065] Step S1, construct the support pile group and slope toe drainage structure 6:

[0066] Clear debris, weeds, and loose soil from the original foundation surface and level the surface. According to the design plan, lay long piles 1 and short piles 2 at predetermined intervals on the original foundation to form a support pile group. After construction, cure the piles for 28 days to ensure the pile strength meets design requirements. Install a slope toe drainage structure 6 at the slope toe 9 and set up settlement monitoring points and horizontal displacement monitoring points. Monitor the slope toe surface settlement through the settlement monitoring points, thus monitoring not only the slope toe surface settlement during the use of the hill but also the slope toe surface settlement caused by the hill construction process. Monitor the horizontal displacement of the slope toe through the horizontal displacement monitoring points, thus monitoring not only the horizontal displacement of the slope toe during the use of the hill but also the horizontal displacement of the slope toe caused by the hill construction process.

[0067] Step S2: Construct the drainage pipe network, bedding layer 3, and leveling layer 4.

[0068] After the support pile group is cured, a drainage pipe network is laid as the drainage pipe network 8.1 at the bottom of the mattress layer. This drainage pipe network is connected to the slope toe drainage structure 6. Then, the mattress layer 3 is laid. The mattress layer 3 includes several layers of graded crushed stone 3.1 and several layers of geogrid I 3.1. A geogrid I 3.1 is set between adjacent layers of graded crushed stone 3.1. After each layer of graded crushed stone 3.1 is laid, it is compacted. When laying the mattress layer 3, the graded crushed stone and geogrid are laid in layers. Ⅰ3.1, compact to a compaction degree of 0.92; pour a leveling layer 4 on top of the mattress layer 3, and use a plate vibrator to compact the leveling layer 4 to ensure that the top surface of the leveling layer 4 is flat and flush with the design elevation; embed pore water pressure monitoring points inside the mattress layer 3; monitor the changes in pore water pressure inside the mattress layer through the pore water pressure monitoring points; thus, it can not only monitor the changes in pore water pressure inside the mattress layer during the use of the hill, but also monitor the changes in pore water pressure inside the mattress layer caused by the construction process of the hill.

[0069] Step S3, Filling construction:

[0070] The fill material is formed by rolling several fill layers 5 one by one. Each fill layer 5 includes several fill unit layers 5.1 and several geogrid II layers 5.2. Each fill unit layer 5 includes several fill unit layers 5.1 and several geogrid II layers 5.2. After each fill unit layer 5.1 is laid, it is rolled and compacted, then geogrid II layers 5.2 are laid, and then another fill unit layer 5.1 is laid, and the construction cycle begins until the fill layer 5 reaches the designed height. In this embodiment, the fill material consists of 12 The filling layer consists of 5 layers; the thickness of each filling layer 5 can be 1~4m. In this embodiment, the thickness of each filling layer 5 is 3m, the compaction coefficient λ≥0.92, and the compression modulus Es≥10MPa, ensuring the density of the filling body and reducing later consolidation settlement. The ends of the geogrid II 5.2 are folded back by no less than 3m, and the distance between the geogrid II 5.2 and the slope surface is no less than 0.5m. The geogrid II 5.2 can enhance the integrity and shear resistance of the filling body, suppress the lateral deformation and delamination slip of the filling body, and reduce differential settlement. The filling unit layer 5.1 is filled with alternating layers of engineering waste soil and recycled fine aggregate, making full use of the engineering characteristics of construction waste to achieve resource utilization. At the same time, the good drainage performance of recycled fine aggregate can promote the drainage consolidation of the filling body. The compaction width of the bottom filling layer 5 is no less than the design width, and the compaction degree gradually decreases by no more than 5% from top to bottom to adapt to the load distribution law and improve the overall stability. A drainage pipe network is laid between adjacent filling layers 5 and connected to the slope toe drainage structure 6. A slope seepage prevention structure 7 is installed on the slope around each fill layer 5. The slope seepage prevention structure 7 includes a water-holding layer 7.1 and a drainage layer 7.2 arranged sequentially from top to bottom. The water-holding layer 7.1 is filled with pre-screened slag soil with a thickness of 0.4-0.6m, and the drainage layer 7.2 is filled with recycled fine aggregate with a thickness of 0.2-0.4m. The interface between the two layers produces a capillary retraction effect due to their different water-holding properties, which can effectively block rainwater infiltration and store some water for the growth of vegetation on the slope, thus achieving both seepage prevention and ecological considerations. The compaction degree of both the water-holding layer 7.1 and the drainage layer 7.2 of the slope seepage prevention structure 7 is not less than 80%. The periphery of the drainage layer 7.2 extends upward to form a surround of the water-holding layer 7.1, with an extension height of not less than 250mm, thereby enhancing the seepage prevention effect.Pore ​​water pressure monitoring points are embedded at the bottom of each fill layer 5 to monitor changes in pore water pressure within each fill layer. This allows for monitoring not only changes in pore water pressure during the use of the hill but also changes caused by the construction process. Settlement and horizontal displacement monitoring points are also installed at the designed locations on the sides, interior, and top of fill layer 5. Settlement monitoring points monitor settlement on the sides, interior, and top of the fill layer, allowing for monitoring of horizontal displacement ...

[0071] Preferably, when filling unit layer 5.1, the filling is carried out from the periphery towards the center. Before each filling layer 5, the engineering waste soil and recycled fine aggregate are mixed evenly, and the moisture content is controlled to be ±2% of the optimum moisture content. Each filling layer 5 is 3m thick. After filling unit layer 5.1 is completed, it is compacted 7 times with heavy compaction equipment at a compaction rate of 2.5km / h. The compaction degree and compression modulus are tested. After passing the test, geogrid II 5.2 is laid, tensioned and leveled, with an overlap length of 50cm, and then folded back and fixed. The above steps are repeated to complete the construction of the filling body.

[0072] Step S4, Debugging of monitoring and early warning devices:

[0073] Wirelessly connect all monitoring points to the data acquisition terminal, debug the monitoring equipment, and ensure stable data transmission; set settlement warning values ​​and differential settlement warning values, complete the debugging of the monitoring and warning system, and realize real-time monitoring of settlement and related parameters.

[0074] Step S5: Post-maintenance and monitoring adjustments.

[0075] Preferably, in the above-mentioned construction method for the settlement control structure of the hill, the post-construction maintenance and monitoring adjustment in step S5 includes: after the hill is completed, the slope is watered to prevent cracking, and the maintenance time is not less than 6 months; during the maintenance period, the data acquisition terminal collects monitoring data every 24 hours to analyze the settlement change pattern; if the settlement amount approaches the warning value, settlement control measures are taken in time until the settlement stabilizes. The settlement control measures include driving additional support piles, adding drainage channels, slowing down the loading speed, and reinforcing the slope; after the settlement stabilizes, the monitoring data collection cycle is extended to once every 72 hours, and the continuous monitoring time is not less than 1 year to ensure that the post-construction settlement is controlled within the design range.

[0076] Preferably, in the above-mentioned construction method for the settlement control structure of the hill, before step S1, engineering survey and scheme design are also included:

[0077] First, determine the planar scope of the land for the hill construction, the design height of the hill, and the slope ratio. Conduct geotechnical engineering investigation to ascertain the lithology, distribution thickness, and physical and mechanical parameters of the original foundation. Use the discrete element method combined with field tests to verify the foundation bearing capacity and settlement, and determine the specific structural parameters and construction technology of the foundation reinforcement layer, fill body, drainage and seepage prevention system, and monitoring and early warning device. At the same time, perform slope stability calculations, considering the slope safety level as a first-class permanent slope, ensuring that the slope stability coefficient is not less than 1.35, and avoiding the mutual influence of slope landslides and settlement.

[0078] Preferably, in the above-mentioned construction method of the hill settlement control structure, the underground drainage structure includes a drainage pipe network 8.1 laid at the bottom of the cushion layer and a drainage pipe network 8.2 laid between adjacent filling layers 5, and the drainage pipe network of each layer is connected to the slope toe drainage structure 6.

[0079] As can be seen from the above, the beneficial effects of the present invention are as follows:

[0080] I. An integrated collaborative control system of "foundation reinforcement - layered filling - drainage and seepage prevention - monitoring and early warning" has been constructed. From foundation treatment, filling construction, waterproofing and drainage to real-time monitoring, it comprehensively prevents and controls the settlement of the hill. It solves the problem of poor single control effect of existing technologies. It can effectively control the post-construction settlement of the hill to no more than 300mm and the differential settlement to no more than 50mm, thereby improving the safety and durability of the hill project.

[0081] Second, the foundation reinforcement layer adopts a composite structure of long and short piles 2 combined with a cushion layer 3 to achieve coordinated reinforcement of the deep and shallow foundations, effectively improve the bearing capacity of the foundation, disperse the load of the hill, reduce uneven settlement of the foundation, adapt to complex geological conditions such as soft soil and fill soil, and solve the settlement hazards caused by insufficient foundation bearing capacity.

[0082] Third, the filling body adopts a graded loading and layered compaction process, and embeds geogrid II5.2 to enhance the integrity. At the same time, it adopts alternating layers of engineering waste soil and recycled fine aggregate, which not only improves the compression and sliding resistance of the filling body, but also realizes the resource utilization of construction waste, reduces the project cost, and combines environmental protection and economy. It can comprehensively absorb a large amount of engineering waste soil and recycled aggregate.

[0083] IV. The drainage and seepage prevention layer adopts a capillary-retaining cover layer combined with slope toe drainage and underground drainage structure to achieve the zoned drainage of surface water and groundwater, effectively blocking rainwater infiltration, lowering the groundwater level, reducing the softening effect of water on the fill and foundation, while taking into account the ecological maintenance of the slope, avoiding the aggravation of settlement and slope landslides caused by water accumulation.

[0084] Fifth, the monitoring and early warning layer enables real-time monitoring and early warning of settlement, horizontal displacement, and pore water pressure. It can promptly grasp the changing patterns of settlement of the hill, detect settlement anomalies in advance, facilitate timely prevention and control measures by staff, prevent the settlement problem from escalating, and achieve precise control of settlement.

[0085] VI. The construction process is convenient, the steps are clear, and the connection between each process is smooth. It does not require complicated large-scale equipment, has high construction efficiency, and can be adapted to pile-up projects of different scales and geological conditions. It is especially suitable for pile-up construction in complex areas such as coastal fill, soft soil, and abandoned mines, and has a wide range of application prospects.

[0086] Example 2

[0087] Please see Figure 11 And can be combined Figures 1 to 10 The settlement control structure and construction method for the artificial hill in this embodiment are applied to an ecological restoration artificial hill project in a soft soil plain area. The designed height of the artificial hill is 10m, the slope ratio is 1:2.0, and the original foundation is a layer of silty soft soil, mainly composed of silty clay, with a thickness of 3-5m. The specific geological parameters are as follows: natural moisture content 40%-55%, natural void ratio 1.2-1.4, compression modulus 4-6MPa, bearing capacity characteristic value 60-100kPa, cohesion 15-22kPa, internal friction angle 8°-12°, and permeability coefficient 1×10⁻ 6 -5×10⁻ 6 The speed is cm / s, which requires solving the problems of soft soil foundation settlement and rainwater infiltration, while realizing the resource utilization of construction waste.

[0088] In this embodiment, the foundation reinforcement layer consists of a support pile group with long pile 1 (cement mixing pile, 10m long, 500mm diameter) and short pile 2 (pressure-grouted plain concrete pile, 5m long, 400mm diameter) arranged alternately, with a spacing ratio of 1:1.2 between long pile 1 and short pile 2. The bottom of long pile 1 is embedded 1m into the bearing layer. The cushion layer 3 is 320mm thick, with graded crushed stone containing 2.8% stone dust and a compaction degree of 0.91. The leveling layer 4 is 90mm thick and is made of plain concrete.

[0089] The filling structure in this embodiment consists of 5 filling layers 5, each with a thickness of 2.0m, a compaction coefficient λ=0.92, and a compression modulus Es=10MPa; the geogrid II 5.2 has a vertical spacing of 2m and is folded back 3.2m at both ends; the engineering waste soil and recycled fine aggregate are mixed in a ratio of 3:1, and the compaction width of the bottom layer is 0.6m wider than the design width.

[0090] In this embodiment, the drainage and seepage prevention layer consists of a slope capillary-retaining cover layer, a water-holding layer 7.1 with a thickness of 0.4m, a drainage layer 7.2 with a thickness of 0.25m, and a compaction degree of 81%; a slope toe blind pipe 6.1 with a diameter of 100mm and a spacing of 1.8m, and a filter layer 6.2 with a thickness of 1m; and an underground drainage network connected to the blind pipe 6.1 to achieve groundwater drainage.

[0091] In this embodiment, the monitoring and early warning layer has a settlement monitoring point spacing of 6m, a horizontal displacement monitoring point spacing of 3.5m, and a pore water pressure monitoring point located at the bottom of each layer of fill. The early warning value is the same as in Embodiment 1.

[0092] In the construction method of the settlement control structure for the artificial hill in this embodiment: the layered filling thickness is controlled at 2.0m, the number of compaction passes is 6, and the compaction rate is controlled at 2km / h; the mixing ratio of construction waste soil and recycled fine aggregate is 3:1; and the curing time after the hill is completed is 6 months. After the completion of this embodiment, the final post-construction settlement is 260mm, and the differential settlement is 38mm, both strictly controlled within the design warning value range, fully meeting the engineering quality requirements. At the same time, this embodiment effectively disposes of approximately 120,000 tons of construction waste soil and approximately 40,000 tons of recycled fine aggregate, realizing the resource-efficient utilization of construction waste, and saving a total of approximately 5 million yuan in engineering costs, fully demonstrating the environmental protection and economic benefits of this invention. The layered filling thickness is controlled at 2m, the number of compaction passes is 6, and the compaction rate is controlled at 2km / h; the mixing ratio of construction waste soil and recycled fine aggregate is 3:1; and the curing time after the hill is completed is 6 months. After the completion of this embodiment, the final post-construction settlement was 260mm, and the differential settlement was 38mm, both strictly controlled within the design warning range, fully meeting the project quality requirements. Simultaneously, this embodiment effectively disposed of approximately 120,000 tons of construction waste and approximately 40,000 tons of recycled fine aggregate, achieving efficient resource utilization of construction waste and saving a total of approximately 5 million yuan in project costs, fully demonstrating the environmental friendliness and economic efficiency of this invention.

[0093] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and all of these should fall within the protection scope of the present invention.

Claims

1. A settlement control structure for manholes, characterized in that, This includes foundation reinforcement layers, fill structures, drainage and seepage prevention systems, and monitoring and early warning devices; The foundation reinforcement layer is laid on top of the original foundation to improve the bearing capacity of the foundation, reduce foundation settlement and surrounding surface deformation. The foundation reinforcement layer includes a support pile group, a cushion layer and a leveling layer. The support pile group is formed by alternating long and short piles, with the bottom of the long piles embedded at least 1m into the bearing layer of the original foundation. The cushion layer is laid on top of the support pile group, and the top elevation of the cushion layer is higher than the top elevation of the support pile group. The cushion layer includes several layers of graded crushed stone and several layers of geogrid I. A layer of geogrid I is set between adjacent graded crushed stone layers. After each layer of graded crushed stone is laid, it is compacted. The leveling layer covers the top of the cushion layer. The fill material covers the top of the foundation reinforcement layer and adopts a layered compaction and reinforcement process to improve the integrity and compressibility of the fill material. The drainage and seepage prevention system is installed inside and around the foundation reinforcement layer and the fill body to guide surface water and groundwater, preventing water infiltration and softening of the fill body and foundation. The drainage and seepage prevention system includes a slope seepage prevention structure, a slope toe drainage structure, and an underground drainage structure, forming a comprehensive drainage and seepage prevention system. The slope seepage prevention structure is installed on the side of the fill layer and on the top surface of the uppermost fill layer. The slope seepage prevention structure is a capillary-retaining cover layer and includes a water-holding layer and a drainage layer arranged sequentially from top to bottom. The underground drainage structure includes a drainage pipe network laid at the bottom of the mattress layer and a drainage pipe network laid between adjacent fill layers. The drainage pipe networks of each layer are connected to the slope toe drainage structure. The monitoring and early warning device is installed in the foundation reinforcement layer, inside and around the filling body, and is used to monitor the settlement, horizontal displacement and pore water pressure of the hill in real time, and issue early warnings and guide adjustments in a timely manner.

2. The settlement control structure for manholes as described in claim 1, characterized in that, The length of the short pile is 1 / 2 to 2 / 3 of that of the long pile, and the spacing ratio between the long pile and the short pile is 1:1.2 to 1.

5.

3. The settlement control structure for a manhole as described in claim 2, characterized in that, The graded crushed stone layer uses graded crushed stone with a particle size of 15mm to 30mm; the thickness of the mattress layer is not less than 300mm, and the mattress layer is composed of graded crushed stone with a particle size of 15mm to 30mm and geogrid I. The graded crushed stone contains no more than 3% of the total weight of crushed stone fragments, and the compaction degree is not less than 0.

9.

4. The settlement control structure for manholes as described in claim 2, characterized in that, The filling body is formed by setting up several filling layers one after another. Each filling layer includes several filling unit layers and several layers of geogrid II. After each filling unit layer is laid, it is compacted. Geogrid II is laid between adjacent filling unit layers. The thickness of each filling layer is 1-4m, the compaction coefficient λ≥0.92, and the compression modulus Es≥10MPa. The filling unit layer is filled with alternating layers of engineering waste soil and recycled fine aggregate.

5. The settlement control structure for a manhole as described in claim 4, characterized in that, The slope toe drainage structure includes drainage blind pipes and a counter-pressure layer arranged around the slope toe. The blind pipes have a diameter of 90mm to 180mm, are made of fibrous plastic, are spaced 1.5-2.5m apart, are arranged at an angle with a slope of not less than 3‰, and extend to the external drainage system of the hill. The filter layer is filled with large-diameter waste stone and has a thickness of not less than 1m.

6. The settlement control structure for a manhole as described in claim 5, characterized in that, The water-holding layer is filled with pre-screened slag and has a thickness of 0.4-0.6m. The drainage layer is filled with recycled fine aggregate and has a thickness of 0.2-0.4m. The compaction degree of both the water-holding layer and the drainage layer of the slope seepage prevention structure is not less than 80%. The drainage layer extends upward around the perimeter to form a ring around the water-holding layer, with an extension height of not less than 250mm.

7. The settlement control structure for a manhole as described in claim 4, characterized in that, The monitoring and early warning device includes settlement monitoring points, horizontal displacement monitoring points, pore water pressure monitoring points, and a data acquisition terminal. The settlement monitoring points include hillside settlement monitoring points, original foundation surface settlement monitoring points, and original foundation soil stratified settlement monitoring points. The hillside settlement monitoring points are arranged in a grid pattern with a spacing of 5-10m, and are placed on the sides and inside of each fill layer to monitor overall settlement and differential settlement. The original foundation surface settlement monitoring points are arranged around the perimeter of the slope toe. The original foundation soil stratified settlement monitoring points are arranged around the toe of the slope at a certain soil layer depth. The horizontal displacement monitoring points include the deep horizontal displacement monitoring points of the original foundation soil and the horizontal displacement monitoring points of the side piles. The deep horizontal displacement monitoring points of the original foundation soil are deployed on the surface of the slope toe soil of each fill layer at intervals of 3-5m to monitor the lateral displacement of the fill layer and prevent landslide disasters. The horizontal displacement monitoring points of the side piles are arranged around the perimeter of the slope toe. The pore water pressure monitoring points are embedded at the bottom of each fill layer. The settlement monitoring points, horizontal displacement monitoring points, and pore water pressure monitoring points are all wirelessly connected to the data acquisition terminal. The settlement warning value is set to be no greater than 300mm, and the differential settlement warning value is set to be no greater than 50mm. When the monitoring data approaches the warning value, the data acquisition terminal will issue a warning signal in a timely manner to facilitate the staff to take prevention and control measures.

8. The settlement control structure for a manhole as described in claim 2, characterized in that, The long piles in the support pile group are cement mixing piles, which use PO42.5 grade ordinary Portland cement with a single-axis admixture of not less than 100 kg / m, a mud-cement ratio of 0.50 to 0.60, and four times of grouting and four times of mixing. The grouting stop surface is 50 cm higher than the design elevation of the pile top to ensure the strength of the pile body and the construction quality. The short piles are pressure-grown plain concrete piles, with a pile diameter deviation of not more than 4% of the design pile diameter, a pile position deviation of not more than 50 mm, and a verticality deviation of not more than 1% of the design verticality deviation.

9. A construction method for a settlement control structure for a manhole as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Step S1: Construct the support pile group and slope toe drainage structure: Clear debris, weeds, and loose soil from the original foundation surface and level the surface. According to the design plan, lay long and short piles at set intervals on the original foundation to form a support pile group. After construction, perform pile curing. Set up a slope toe drainage structure and lay settlement monitoring points and horizontal displacement monitoring points at the slope toe. Begin monitoring the surface settlement at the slope toe through the settlement monitoring points. Begin monitoring the horizontal displacement at the slope toe through the horizontal displacement monitoring points. Step S2: Construct the drainage pipe network, bedding layer, and leveling layer. After the support pile group is cured, a drainage pipe network is laid and connected to the slope toe drainage structure. Then, a mattress layer is laid, which includes several layers of graded crushed stone and several layers of geogrid I. A geogrid I layer is set between adjacent graded crushed stone layers. After each layer of graded crushed stone is laid, it is compacted. A leveling layer is poured on top of the mattress layer. Pore water pressure monitoring points are embedded in the mattress layer. The changes in pore water pressure inside the mattress layer are monitored through the pore water pressure monitoring points. Step S3, Filling construction: The fill body is formed by rolling several fill layers one by one. Each fill layer includes several fill unit layers and several layers of geogrid II. After each fill unit layer is laid, it is rolled. Geogrid II is laid between adjacent fill unit layers. The thickness of each fill layer is 1-4m, the compaction coefficient λ≥0.92, and the compression modulus Es≥10MPa. The fill unit layers are filled with alternating layers of engineering waste soil and recycled fine aggregate. A drainage network is laid between adjacent fill layers and connected to the slope toe drainage system. The water structure is interconnected; a slope seepage prevention structure is set on the slope around each fill layer, the slope seepage prevention structure including a water-holding layer and a drainage layer arranged sequentially from top to bottom; pore water pressure monitoring points are embedded at the bottom of each fill layer to monitor changes in pore water pressure inside each fill layer; settlement monitoring points and horizontal displacement monitoring points are set on the sides, inside, and top of the fill layer according to the design location; settlement on the sides, inside, and top of the fill layer is monitored through the settlement monitoring points. The horizontal displacement of the fill layer's sides, interior, and top of the slope is monitored starting from the horizontal displacement monitoring points. Step S4, Debugging of monitoring and early warning devices: Wirelessly connect all monitoring points to the data acquisition terminal, debug the monitoring equipment, and ensure stable data transmission; set settlement warning values ​​and differential settlement warning values, complete the debugging of the monitoring and warning system, and realize real-time monitoring of settlement and related parameters; Step S5: Post-maintenance and monitoring adjustments.

10. The construction method of the settlement control structure for a manhole as described in claim 9, characterized in that, In step S5, the post-construction maintenance and monitoring adjustments include: after the hill is completed, the slope is watered to prevent cracking, and the maintenance period is no less than 6 months; during the maintenance period, the data acquisition terminal collects monitoring data every 24 hours to analyze the settlement change pattern; if the settlement amount approaches the warning value, settlement control measures are taken in a timely manner until the settlement stabilizes. The settlement control measures include driving additional support piles, adding drainage channels, slowing down the loading speed, and reinforcing the slope; after the settlement stabilizes, the monitoring data collection cycle is extended to once every 72 hours, and the continuous monitoring period is no less than 1 year to ensure that the post-construction settlement is controlled within the design range.

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