Static pressure ramming and expanding compaction pile composite foundation construction method based on solid waste utilization

Abstract

The application discloses a kind of static pressure ramming expansion extrusion pile composite foundation construction methods based on solid waste utilization, steps are as follows: first, level the site, reserve protective layer and release pile position;Electric static pressure steel pipe pile equipment with front end closed pointed structure is in place leveling;Steel pipe is aligned and pressed into hole, adopts row spacing, interval one pile position jump and beats way, to design depth stop pressurization;After hole forming, pull out steel pipe, shift equipment, cover hole with cover plate;Before filling, empty ramming in hole bottom, and filling is layered to hole mouth, complete first sequence pile construction;Second sequence pile is constructed using the above steps repeatedly in skip row and skip row mode;Subsequent each sequence pile is sequentially constructed until completed;Remove protective layer, check pile diameter, pile number and pile position, detect single pile and composite foundation bearing capacity;After acceptance, carry out next process.The method meets environmental protection requirements, reduces construction cost and realizes solid waste resource utilization under the premise of ensuring hole forming effect and pile quality.

Description

Technical Field

[0001] This invention belongs to the field of building foundation construction, specifically relating to a static pressure ramming and compaction pile composite foundation construction method based on solid waste utilization. Background Technology

[0002] In the field of building foundation construction, compaction piles are often used to treat poor foundations such as collapsible loess and soft soil. Compaction piles work by drilling holes, filling and compacting the soil around the piles, thus eliminating collapsibility and improving the bearing capacity of the foundation. Plain soil compaction piles and cement-soil compaction piles are two common types.

[0003] Currently, the main hole-forming methods for compaction pile construction in collapsible loess areas in China are as follows: First, using a Luoyang shovel or mechanical Luoyang shovel to form the hole, followed by layered filling and compaction to form the pile; second, using a long spiral drilling rig or a short spiral drilling rig to form the hole, followed by layered filling and compaction to form the pile; third, using a column hammer to expand and compact the hole, followed by filling and compaction to form the pile; and fourth, using a diesel hammer to drive the driven pipe to the designed depth, then pulling out the driven pipe, and finally filling and compacting to form the pile.

[0004] Taking a foundation treatment project of a large cement plant as an example, this project required the construction of plain soil compaction piles and cement-soil compaction piles, with a drilling depth of 15.5m and a hole diameter of 560mm. The construction team successively tested various drilling techniques. The Luoyang shovel and mechanical Luoyang shovel methods had limited drilling depth, were prone to hole collapse, and had unsatisfactory compaction effects on the soil between piles. Long spiral and short spiral drilling methods also suffered from hole collapse and poor compaction effects. The column hammer tamping compaction pile method generated significant vibration and impact during construction, significantly affecting surrounding already constructed piles and posing safety hazards. While the diesel hammer driven pipe drilling method could meet the drilling depth and compaction requirements, the diesel hammer emitted diesel exhaust gas during operation, while also generating strong vibrations and noise.

[0005] With increasingly stringent environmental protection requirements, the control of environmental impact factors such as exhaust emissions, vibration, noise, and light pollution at construction sites is becoming increasingly strict. Among the existing methods mentioned above, the diesel hammer pipe-driving process fails to meet environmental regulatory requirements due to exhaust pollution, vibration, and noise issues; the column hammer ramming process has a significant impact on adjacent piles due to vibration and impact, and also presents noise problems; the Luoyang shovel and auger drilling methods fail to guarantee the quality of foundation treatment due to poor hole quality and compaction effect. Furthermore, existing construction methods typically require the purchase of large quantities of excavated soil as fill material, failing to effectively utilize the excavated soil or other solid waste generated at the construction site.

[0006] Therefore, how to meet environmental protection requirements while ensuring the drilling depth, soil compaction effect between piles and pile quality, and at the same time reduce construction costs and realize the resource utilization of solid waste has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a construction method for a static pressure compaction pile composite foundation based on solid waste utilization. Its purpose is to meet environmental protection requirements while ensuring the drilling depth, the compaction effect of the soil between piles, and the quality of the pile body, thereby reducing construction costs and realizing the resource utilization of solid waste.

[0008] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: A method for constructing a static pressure compaction pile composite foundation based on solid waste utilization includes the following steps: Step 1: Level the site and reserve a protective layer, then mark out the pile positions; Step 2: Position and level the electrostatic pressure steel pipe pile equipment. The front end of the steel pipe of the electrostatic pressure steel pipe pile equipment is a fully enclosed pointed structure. Step 3: Align the steel pipe with the pile position and press it down to form a hole. Measure the depth of the steel pipe into the soil and stop pressurizing after it reaches the designed depth. The pressing and hole-forming process adopts a method of skipping rows and columns, with each pile position being alternated. Step 4: After drilling, pull out the steel pipe and move the electrostatic pressure steel pipe pile equipment, while covering the hole with a cover plate. Step 5: Before filling the hole, perform a dry compaction at the bottom of the hole, then fill the hole in layers and compact each layer, controlling the number of compactions for each layer until the hole opening is reached; this completes the construction of the first pile. Step six: Using a skip-row and skip-row method, repeat steps three to five to construct the second sequence of piles; Step 7: Repeat steps 3 to 5 to construct the subsequent piles in sequence until all rammed and enlarged piles are completed. Step 8: After removing the protective layer, check the pile diameter, number of piles, and pile location, and conduct bearing capacity tests on single piles and single pile composite foundations; Step nine: After acceptance, proceed to the next construction process.

[0009] Furthermore, the number of times the air compaction is performed in step five is three.

[0010] Furthermore, the material used for layered filler in step five is solid waste, which includes soil excavated from high parts of the site, or recycled soil obtained from construction waste after sorting and crushing.

[0011] Furthermore, when the solid waste is mixed with cement to prepare cement-soil filler, the solid waste is passed through a 2×2cm sieve and then mixed with cement at a volume ratio of 1:6. The moisture content of the mixture is tested by the following method: the mixture is squeezed into a ball in the hand and dropped freely from a certain height above the ground and then dispersed. If this condition is not met, water is sprayed onto the mixture and it is stirred evenly until it meets the requirements.

[0012] Furthermore, in step five, the layered compaction employs a winch-lifted compactor. The hammer weight of the winch-lifted compactor is not less than 15KN, the hammer lifting height is 5m, and the volume of each layer of fill material is not greater than 0.25m³. 3 After three air compactions, each layer is first lightly tapped twice at a height of 2m, and then tamped seven times at a height of 5m.

[0013] Furthermore, when there is insufficient soil on the construction site, a closed mixing plant is set up on site to crush construction waste and mix it with cement to make cement-soil filler. The closed mixing plant is equipped with a 2×2cm screen.

[0014] Furthermore, when carrying out foundation pit support in peat soil strata, the aforementioned electrostatic pressure steel pipe pile equipment is used to press dumbbell-shaped double steel pipes into the design depth, remove the inner pipe and the soil plug inside the pipe, insert an H-shaped steel with a central support and adjust it to be centered, and then pour in cement-soil slurry made of crushed solid waste and cement. After solidification, a foundation pit support structure integrating water-stopping support is formed.

[0015] Furthermore, in the construction of long spiral hole drilling and concrete grouting followed by the insertion of the reinforcing cage, the aforementioned electrostatic pressure steel pipe pile equipment is used as the pile delivery pipe to insert the reinforcing cage with a central support into the concrete of the pile hole, so that the reinforcing cage remains centered in the pile hole.

[0016] Furthermore, in step eight, the protective layer is removed manually in conjunction with a small excavator reversing backward.

[0017] Furthermore, after conducting bearing capacity tests on single piles and single-pile composite foundations in step eight, the compaction coefficients of the pile body and the soil between piles are also tested by drilling exploratory wells in the pit. The pile body compaction coefficient is not less than 0.97, and the soil compaction coefficient between piles is not less than 0.93. Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a method for constructing a composite foundation using static pressure compaction piles based on solid waste utilization. It employs an electric static pressure steel pipe pile device for hole formation. The steel pipe has a fully enclosed pointed front end, and the pipe is pressed into the soil layer by static pressure. The entire process is electrically driven, eliminating the need for diesel fuel combustion, thus producing no diesel exhaust emissions and avoiding the vibration and noise associated with traditional hammering equipment. This directly addresses the shortcomings of diesel hammer technology, which has been halted due to environmental concerns, ensuring that construction meets on-site environmental requirements regarding exhaust emissions, vibration, and noise. Hole formation employs a skip-row, alternating-row method, with each pile position spaced apart, and the hole opening is immediately covered with a cover plate after formation. This skip-row sequence and timely covering prevent shrinkage or collapse between adjacent pile holes due to soil compression. Compared to existing technologies such as column hammer compaction, which significantly impacts adjacent piles due to vibration and impact, and the tendency for holes to collapse with a Luoyang shovel, this invention ensures hole quality while minimizing disturbance to surrounding existing piles. The static compaction method involves pressing a steel pipe into the soil layer. The pointed structure at the front end of the pipe reduces penetration resistance, and the pipe wall exerts a radial compaction effect on the surrounding soil, eliminating the need for impact force like a diesel hammer. This static compaction method increases the density of the soil around the pile without damaging the soil structure, providing good side constraint conditions for the compaction of the fill material. Before filling, air compaction is performed at the bottom of the hole, followed by layered filling and compaction, controlling the number of blows per layer until the hole opening. Air compaction eliminates loose soil at the bottom of the hole, and layered compaction ensures that each layer of fill material reaches the designed density, avoiding the problem of insufficient compaction at the bottom due to excessive filling at once, as seen in traditional methods. A sequential construction method is adopted, completing the first-sequence piles first, then constructing the second-sequence piles in a skip-row manner, and subsequently constructing the subsequent piles in sequence until all are completed. This sequential operation mode allows for the phased construction of densely packed piles, giving the completed piles sufficient time to stabilize and gradually releasing soil stress. This avoids site heave or pile displacement that might occur with a single, large-scale construction, ensuring the overall uniformity of the foundation treatment. After construction is completed, the protective layer is removed, and the pile diameter, number of piles, and pile location are inspected. Single pile and single-pile composite foundation bearing capacity tests are conducted. Following these tests, compaction coefficients are measured by drilling exploratory wells within the pit to obtain samples from the pile shaft and the soil between piles. Only after passing these tests can the next process proceed. This testing and acceptance process ensures that the bearing capacity of each pile and the overall composite foundation meets design requirements.

[0018] In summary, the method of the present invention effectively solves the problems of non-compliance with environmental protection standards, mutual influence between adjacent piles, and easy collapse of the borehole in the prior art, while ensuring the drilling depth, the soil compaction effect between piles, and the quality of the pile body. At the same time, it has high construction efficiency and controllable cost, and is suitable for the treatment of various poor foundations such as collapsible loess. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a construction method for a static pressure compaction pile composite foundation based on solid waste utilization, as an example. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 Combination Figure 1 As shown, taking the foundation treatment project of a 10,000 t / d clinker second-generation new dry process cement production line of a special cement company as an example, the compaction pile construction area includes sub-items such as raw material grinding and exhaust gas treatment, kiln tail, kiln middle, and clinker silo. The total workload of plain soil compaction piles is approximately 97,472 m. 3 Cement-soil compaction piles: approximately 4864m 3 The site is located on the Weibei Loess Plateau, with a foundation collapse level of III to IV and a collapse thickness of 24m to 27m, belonging to a thick collapsible loess foundation.

[0023] Step 1: Level the site and reserve a protective layer, then mark the pile positions. Before construction, level the site, reserve a 50cm thick protective layer, and mark the pile positions after measuring the elevation. When determining the pile positions, use a steel chisel or hole drill to make a deep hole in the ground, fill it with white lime powder, and insert a wooden stick or steel rod at the pile position as a clear marker. Use measuring instruments to make positioning stakes at both ends, and if necessary, project the control line to a fixed object at a distance for verification at any time.

[0024] Step two involves positioning and leveling the electrostatic pressure steel pipe pile equipment. The front end of the steel pipe of the equipment is a fully enclosed pointed structure. This equipment is driven by electrostatic pressure, producing no diesel exhaust emissions, vibration, noise, or light pollution during construction. A total of four static pressure pile drivers are deployed on site, each producing a 18m long, 560mm diameter borehole. Additionally, eight winch-type tampers, nine loaders, and two water trucks are also available.

[0025] Step 3: Align the steel pipe with the pile location and drive it into the hole. Measure the depth of the steel pipe into the soil; stop pressurizing after it reaches the designed depth. The drilling is done by skipping rows and pile locations. After drilling, measure the depth of the steel pipe into the soil; stop pressurizing when the designed depth of 15.5m is reached. For overall treatment, proceed from the inside out; for partial treatment, proceed from the outside in. One drilling recorder is assigned to monitor the drilling quality, measure the drilling for each pile, and record it according to a unified number. Record a number for each hole that meets the standard. After acceptance, replace the hole cover. Drill holes that do not meet the standard again until they do. Summarize the results daily and mark them with a circle (⊙) on the pile location map.

[0026] Step four: After drilling, pull out the steel pipe and move the electrostatic pressure steel pipe pile equipment, while simultaneously covering the borehole opening with a cover plate. This prevents compression from adjacent holes, which could cause borehole shrinkage or collapse. Cover each hole as it is completed, and a designated person should keep records.

[0027] Step five: Before filling the hole, perform air compaction at the bottom. Then, fill the hole in layers and compact each layer, controlling the number of blows for each layer until the hole opening. This completes the construction of the first pile.

[0028] Step six: Using a skip-row, skip-layout method, repeat steps three through five to construct the second-order piles. After the first-order piles are completed, use a skip-row, skip-layout method to repeat the above-mentioned drilling, filling, and compaction steps to construct the second-order piles.

[0029] Step seven: Repeat steps three through five, constructing each subsequent pile in sequence until all rammed and expanded piles are completed. Then repeat the above steps, constructing each subsequent pile in sequence until all rammed and expanded piles are completed. Depending on the pile location, four stages are required to complete all piles in actual construction.

[0030] Step 8: After removing the protective layer, check the pile diameter, number of piles, and pile location, and conduct bearing capacity tests on single piles and single-pile composite foundations. After all piles are constructed, the protective layer is removed manually in conjunction with a small excavator. The pile diameter, number of piles, and pile location are checked, and the bearing capacity of single piles and single-pile composite foundations is tested. A total of 12 test points were selected, with a termination load of 400 kPa. The cumulative settlement of the 12 test points ranged from 14.41 mm to 19.87 mm, and the characteristic value of the bearing capacity at each test point was greater than 200 kPa.

[0031] Step nine: After acceptance, proceed to the next construction process. After acceptance, lay the mattress layer; after the mattress layer passes acceptance, proceed to the next construction process.

[0032] In this embodiment, an electrostatic pressure steel pipe pile device is used instead of a traditional diesel hammer, eliminating exhaust gas, vibration, and noise pollution and meeting environmental protection requirements. The skip-driving method effectively prevents hole shrinkage and collapse caused by adjacent hole compression, ensuring hole quality. Layered filling and layered compaction control the pile quality. The entire construction process is highly efficient, reliable in quality, and has a low project cost.

[0033] Example 2 In step five, the air tamping at the bottom of the hole before filling is performed three times. Specifically, the tamping hammer is raised to a height of 5 meters and allowed to fall freely, repeated three times. After three air tamping sessions, the bottom of the hole is compacted, eliminating loose soil and providing a solid foundation for subsequent layered filling and compaction. Three air tamping sessions are a reasonable number determined through testing in this project, ensuring effective compaction of the hole bottom without over-compacting and damaging the soil. On-site testing showed that the density of the hole bottom significantly improved after three air tamping sessions, effectively guaranteeing the pile tip bearing capacity.

[0034] Example 3 In step five, the material used for the layered filler is solid waste. In this cement plant project, the site has elevation differences. Before construction, the soil in the higher areas was excavated, and this excavated soil was directly used as filler for the plain soil compaction piles, achieving on-site material sourcing. The soil material must be tested for organic matter content before use, requiring it to be no more than 5%, using a laboratory roasting method. The soil material must be sieved, with a particle size no larger than 20mm. In addition, there is construction waste from building demolition around the project site. After sorting and removing impurities, it is crushed to a particle size no larger than 20mm using a crusher. The resulting recycled soil material is mixed with cement and used as filler for the cement-soil compaction piles. A sieving device with a 2×2cm screen size is provided at the construction site to ensure the filler particle size meets the requirements. Using solid waste as filler reduces the cost of purchasing external soil, while simultaneously disposing of construction waste and avoiding the need for off-site soil transportation, resulting in significant economic and environmental benefits.

[0035] Example 4 When mixing solid waste with cement to prepare cement-soil filler, first pass the solid waste through a 2×2cm sieve to remove large particles and impurities, then mix it with cement at a volume ratio of 1:6. Use P.O32.5 grade ordinary Portland cement. Before use, samples must be taken and tested under the supervision of the supervisor; the cement can only be used after passing the test.

[0036] After preparation, the moisture content of the mixture needs to be checked. The following method is used on-site to check the moisture content: Squeeze the mixture into a ball in your hand and drop it freely from a certain height above the ground. If the mixture disperses naturally upon landing, the moisture content is appropriate; if it does not disperse or remains in a cake-like shape, the moisture content is too high; if it cannot be squeezed into a ball at all, the moisture content is too low. If the condition is not met, spray water onto the mixture and stir it thoroughly, then check again until it meets the requirements.

[0037] Cement-soil mixing is carried out using a mixing machine. It is mixed and used immediately according to backfill requirements; mixed cement-soil must not be used within 2 hours, and overnight cement-soil is strictly prohibited from use. Cement-soil mixing is not carried out during rainy periods; cement-soil that has been soaked or immersed by rain is discarded. By controlling the moisture content within the optimal range, the compaction density and strength of the cement-soil after compaction are guaranteed. Field tests show that cement-soil filler with moisture content controlled according to this method achieves a compaction coefficient of over 0.97 for the compacted piles.

[0038] Example 5 Step five, layered compaction, utilizes a winch-lifted compactor with a frame height of at least 5 meters, a hammer weight of 15 kN, and a hammer lifting height of 5 meters. The volume of each layer of fill material should not exceed 0.25 cubic meters. 3 Each layer of fill material is approximately 1 meter thick. After three dry compaction cycles, the compaction process for each layer is divided into two stages: first, the tamping hammer is raised to a height of 2 meters and lightly struck twice to initially compact and level the fill material; then, the tamping hammer is raised to a height of 5 meters and heavily struck seven times to achieve the designed compaction density. Each layer of fill material is constructed according to these parameters until the borehole opening. When constructing at the top of the pile, the number of tamping blows can be appropriately increased depending on the height of the tamping hammer. Testing showed that the compaction coefficient of the pile body constructed according to these parameters is 0.97 to 0.99, meeting the design requirements.

[0039] Example 6 When there is insufficient soil at the construction site, a closed-loop mixing plant is set up on-site to crush construction waste and mix it with cement to create cement-soil filler. The closed-loop mixing plant is equipped with a 2×2cm screen. Specifically, the construction company sets up a closed-loop mixing plant on-site, purchases construction waste from the surrounding area, sorts and crushes it, and uses it as a substitute for soil. The mixing plant is equipped with a 2×2cm screen to ensure that the particle size of the crushed construction waste meets the requirements. The crushed construction waste and cement are added to the mixer at a volume ratio of 1:6, and water is added as needed based on the moisture content test results. After thorough mixing, it is transported by a loader to the work face for compaction. The use of a closed-loop mixing plant effectively controls dust and meets environmental protection requirements. This method solves the problem of insufficient soil supply while simultaneously disposing of a large amount of construction waste, turning waste into a valuable resource.

[0040] Example 7 When carrying out foundation pit support in peat soil strata, the aforementioned electrostatic pressure steel pipe pile equipment is used to press dumbbell-shaped double steel pipes into the design depth, remove the inner pipe and the soil plug inside the pipe, insert an H-shaped steel with a central support and adjust it to be centered, and then pour in cement-soil slurry made of crushed solid waste and cement. After solidification, a foundation pit support structure integrating water-stopping support is formed.

[0041] The project site is located in a peat soil stratum. The organic matter in the peat soil hinders the hydration reaction of cement. Conventional cement mixing piles, jet grouting piles, and stir-grouting piles cannot form an effective cement solidification body in this stratum, resulting in poor water-stopping effect. In this project, an electrostatic pressure steel pipe pile device was used to press a specially designed dumbbell-shaped double steel pipe into the designed depth. The double steel pipe consists of an outer pipe and an inner pipe. During the pressing process, soil enters the inner pipe to form a soil plug. After pressing to the designed depth, the inner pipe and the soil plug inside the pipe are removed, leaving the outer pipe underground. Then, an H-beam with a centering support is inserted, and the position of the H-beam is adjusted to be centered using the centering support. Next, a cement-soil grout, made from crushed solid waste mixed with cement, is poured in. The grout fills the gap between the outer pipe and the H-beam, as well as the soil at the bottom of the outer pipe. After the outer pipe is pulled out, the cement-soil grout has solidified, forming an integrated water-stopping and support structure for the foundation pit together with the H-beam. On-site inspection showed that the support structure had a good water-stopping effect, and there was no obvious water seepage on the excavation surface of the foundation pit.

[0042] Example 8 This embodiment applies the above construction method to the installation of reinforcing cages after long spiral drilling and concrete grouting. In this process, the electrostatic pressure steel pipe pile equipment is used as the pile driving pipe to insert the reinforcing cage, equipped with a central support, into the concrete of the pile hole, ensuring the cage remains centered within the hole.

[0043] A certain project used a long spiral drilling and pressure-grouting concrete process to construct compression and tension piles. The piles were designed as reinforced concrete piles, requiring the insertion of reinforcing cages into the concrete. However, after construction using conventional methods, excavation and inspection revealed that each reinforcing cage was offset to one side of the borehole wall, with none centered. The protective layer thickness failed to meet the specifications and design requirements, and the designer refused to accept the project. To solve this problem, an electrostatic pressure (ESP) steel pipe pile driver was used as the pile delivery pipe. The specific procedure was as follows: after drilling the hole with a long spiral drilling rig, concrete was grouted. Before the concrete initially set, the steel pipe of the ESP was placed into a reinforcing cage with a centering support, with the front end of the pipe open. The pipe was then aligned with the pile hole and statically inserted into the concrete. After reaching the designed depth, the pipe was pulled out, leaving the reinforcing cage in the concrete. Due to the good verticality of the ESP and the support of the centering support, the reinforcing cage remained centered within the pile hole. Post-excavation inspection showed that each reinforcing cage was centered, and the protective layer thickness met the design requirements. This embodiment retains the advantages of long spiral hole-forming pressure grouting concrete construction, such as high efficiency, dry operation, no mud pollution, and no soil squeezing effect, while solving the problem of the rear-inserted steel cage not being centered.

[0044] Example 9 Step eight involves removing the protective layer using a combination of manual labor and a small excavator working backwards. Specifically, the small excavator starts from the edge of the site and excavates the protective soil layer backwards, working from the outside in and from the farthest point to the nearest point. The excavator's tracks remain on the site surface after the protective layer has been removed, avoiding any crushing damage to the already constructed piles. The excavator bucket removes the protective layer soil to approximately 5cm above the designed pile top elevation. The remaining portion is then manually cleared to the pile top elevation using shovels, while simultaneously removing any loose parts from the pile head. This backward-moving method effectively protects the piles from mechanical damage, ensuring the integrity of the pile head. After removal, the pile head is exposed, facilitating subsequent inspection and testing of the pile diameter, number of piles, and pile location.

[0045] Example 10 After conducting bearing capacity tests on single piles and single pile composite foundations in step eight, the compaction coefficients of the pile body and the soil between piles are also tested by drilling exploratory wells in the pit. The compaction coefficient of the pile body is not less than 0.97, and the compaction coefficient of the soil between piles is not less than 0.93.

[0046] The specific procedure was as follows: Four test wells were dug at the site according to the required sampling quantity. Samples were taken from three piles in each well, with 16 samples taken from each pile, for a total of 192 samples, to test the pile compaction coefficient. Sixteen soil samples were also taken from each well at a location 10cm from the pile edge and at half the distance between two piles, for a total of 128 samples, to test the soil compaction coefficient between piles. The test results were as follows: the pile compaction coefficient ranged from 0.97 to 0.99, with an average value not less than 0.97; the average soil compaction coefficient between piles ranged from 0.93 to 0.96, with an average value not less than 0.93. Simultaneously, 112 samples were taken to test the collapsibility coefficient, and the test results were all less than 0.015, indicating that collapsibility had been eliminated within the treated depth range.

[0047] Quality inspection during construction should be carried out according to the following standards. Key control items include: the number, arrangement, size, borehole diameter, depth, fill material quality, and mix ratio of cement-soil (plain soil) compaction piles, which must meet the design requirements or construction specifications. General items include: before construction, checking the quality of the soil and cement-soil mixture, and the location of the pile holes; during construction, checking the pile hole diameter, pile hole depth, number of blows, and moisture content of the fill material; after construction, randomly checking the required quantity, drilling exploratory wells in the pit to obtain the compaction coefficient of the pile body and the soil between piles, and checking the quality of the piles and the bearing capacity of the foundation.

[0048] The quality inspection standards for cement-soil (plain soil) compaction pile projects are shown in Table 1 below: Table 1

[0049] The control measures for key control points in special processes are shown in Table 2 below: Table 2

[0050] Quality records should include: records of concealed works, records of cement-soil compaction pile construction, records of surveying and setting out, and records of quality acceptance of inspection batches.

[0051] During construction, verticality must be controlled, with a deviation of less than 1.5%, measured using a theodolite. Pile position deviations should meet the following requirements: no more than 0.4 times the pile diameter for full-span piles and no more than 0.25 times the pile diameter for strip foundation piles, measured with a steel ruler. These indicators must meet design requirements and construction specifications.

[0052] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A construction method for a static pressure compaction pile composite foundation based on solid waste utilization, characterized in that, Includes the following steps: Step 1: Level the site and reserve a protective layer, then mark out the pile positions; Step 2: Position and level the electrostatic pressure steel pipe pile equipment. The front end of the steel pipe of the electrostatic pressure steel pipe pile equipment is a fully enclosed pointed structure. Step 3: Align the steel pipe with the pile position and press it down to form a hole. Measure the depth of the steel pipe into the soil and stop pressurizing after it reaches the designed depth. The pressing and hole-forming process adopts a method of skipping rows and columns, with each pile position being alternated. Step 4: After drilling, pull out the steel pipe and move the electrostatic pressure steel pipe pile equipment, while covering the hole with a cover plate. Step 5: Before filling the hole, perform a dry compaction at the bottom of the hole, then fill the hole in layers and compact each layer, controlling the number of compactions for each layer until the hole opening is reached; this completes the construction of the first pile. Step six: Using a skip-row and skip-row method, repeat steps three to five to construct the second sequence of piles; Step 7: Repeat steps 3 to 5 to construct the subsequent piles in sequence until all rammed and enlarged piles are completed. Step 8: After removing the protective layer, check the pile diameter, number of piles, and pile location, and conduct bearing capacity tests on single piles and single pile composite foundations; Step nine: After acceptance, proceed to the next construction process.

2. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 1, characterized in that, The air compaction in step five is performed three times.

3. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 1, characterized in that, The material used for layered filling in step five is solid waste, which includes soil excavated from high parts of the site, or recycled soil obtained from construction waste after sorting and crushing.

4. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 3, characterized in that, When the solid waste is mixed with cement to prepare cement-soil filler, the solid waste is passed through a 2×2cm sieve and then mixed with cement at a volume ratio of 1:

6. The moisture content of the mixture is tested by the following method: the mixture is squeezed into a ball in the hand and dropped freely from a certain height above the ground and then dispersed. If the condition is not met, water is sprayed onto the mixture and stirred evenly until it meets the requirements.

5. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 1, characterized in that, The layered compaction in step five employs a winch-lifted compactor. The hammer weight of the winch-lifted compactor is no less than 15KN, the hammer lifting height is 5m, and the volume of each layer of fill material is no greater than 0.25m³. 3 After three air compactions, each layer is first lightly tapped twice at a height of 2m, and then tamped seven times at a height of 5m.

6. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 1, characterized in that, When there is insufficient soil on the construction site, a closed mixing plant is set up on site to crush construction waste and mix it with cement to make cement-soil filler. The closed mixing plant is equipped with a 2×2cm screen.

7. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 1, characterized in that, When carrying out foundation pit support in peat soil strata, the aforementioned electrostatic pressure steel pipe pile equipment is used to press dumbbell-shaped double steel pipes into the design depth, remove the inner pipe and the soil plug inside the pipe, insert an H-shaped steel with a central support and adjust it to be centered, and then pour in cement-soil slurry made of crushed solid waste and cement. After solidification, a foundation pit support structure integrating water-stopping support is formed.

8. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 1, characterized in that, In the construction of long spiral hole drilling and concrete grouting followed by the insertion of the reinforcing cage, the aforementioned electrostatic pressure steel pipe pile equipment is used as the pile delivery pipe to insert the reinforcing cage with a central support into the concrete of the pile hole, so that the reinforcing cage remains centered in the pile hole.

9. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 1, characterized in that, In step eight, the protective layer is removed manually in conjunction with a small excavator reversing backward.

10. The construction method for a static pressure compaction pile composite foundation based on solid waste utilization according to claim 1, characterized in that, After conducting bearing capacity tests on single piles and single pile composite foundations in step eight, the compaction coefficients of the pile body and the soil between piles are also tested by drilling exploratory wells in the pit. The compaction coefficient of the pile body is not less than 0.97, and the compaction coefficient of the soil between piles is not less than 0.93.

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