Construction method for cooperatively enhancing bearing capacity of soft foundation through solidified pier and geogrid

Abstract

The invention discloses a construction method for cooperatively enhancing the bearing capacity of a soft foundation through solidified piers and geogrids, and relates to the technical field of building construction, the construction method comprises the following steps: step 1, construction preparation: performing preparation inspection on a test device and a construction material; 2, pier body construction, wherein a proper pier body is selected for treatment according to geological requirements; thirdly, cement soil is modified, cement is spread manually after the pier top is leveled, and mixing is conducted through a road mixer; and 4, settlement observation is conducted, specifically, a settlement observation plate is buried after cement soil is subjected to reverse excavation, and the settlement observation plate is arranged at the center line of the shortcut. According to the construction method for cooperatively enhancing the bearing capacity of the soft foundation through the solidified pier and the geogrid, the engineering quality is improved through wet-method pier body construction and dry-method pier body construction, the problem that the soft foundation is difficult to construct is solved, cement is manually spread after the pier top is leveled, the problem that the pier top is solidified unevenly is solved, and meanwhile the bearing capacity of the soft foundation is enhanced. The bearing capacity of the roadbed base is further improved.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a construction method for synergistically enhancing the bearing capacity of soft soil foundations using solidified piers and geogrids. Background Technology

[0002] Soft soil foundations refer to weak soil layers with low strength and high compressibility, often containing a certain amount of organic matter. Due to their low strength and large settlement, soft soil often poses significant risks to road engineering. Improper handling can severely impact highway construction and use. The properties of soft soil foundations vary depending on the location and soil layer, making them highly unpredictable. Even slight negligence during design and construction can lead to quality issues. Summary of the Invention

[0003] The purpose of this invention is to provide a construction method for synergistic enhancement of soft soil bearing capacity by combining solidified piers and geogrids, thereby solving the problem of quality accidents that easily occur in the construction of soft foundations in the prior art and improving the bearing capacity of the foundation.

[0004] To achieve the above objectives, the present invention provides a construction method for synergistically enhancing the bearing capacity of soft soil foundations using solidified piers and geogrids, comprising the following steps: Step 1: Construction preparation, including preparation and inspection of the testing equipment and construction materials; Step 2: Pier construction. Select appropriate pier treatment methods according to geological requirements. Pier construction includes dry construction and wet construction. Step 3: Cement-soil modification. After the in-situ solidified pile area test is qualified, the measurement and layout are carried out again, the site is leveled and static pressure is applied, and cement is manually spread and mixed by a road mixing machine after the pier top is leveled. Step 4: Settlement monitoring. Settlement monitoring boards are installed in reverse excavation behind the cement-soil road. The settlement monitoring boards are set at the center line of the access road. Settlement is monitored every 7 days after the roadbed construction is completed.

[0005] Preferably, in step two, the thickness of the geogrid composite layer in the wet-laid pier is 0.5m, and the pier is arranged in a rectangular shape. The wet construction method for piers includes the following steps: S11. Clear and level the surface. Use an excavator to remove the turf and humus within the survey and setting-out area. After removing the topsoil, transport it to the designated spoil disposal site. Backfill and compact the pits according to the specifications, and level the site. S12. Layout and positioning: Based on the soft soil treatment range, lay out the construction side piles in 20m sections. Lay out the starting point, ending point, left side line, right side line, and center pile position for the construction section. Based on the measurement layout range and pile position layout diagram, use a 50m steel tape and RTK to determine the axis of each row of piles and the center of each pile, and mark them with lime and wooden piles. S13. Positioning of the curing mixer: Before construction, complete the acceptance inspection of cement and curing agent upon arrival. Mix the curing slurry according to the mix ratio. Align the center of the mixer drill bit with the center of the pile position. Adjust the mixer to be level and stable. Mark the depth control line on the mixer's mechanical arm. S14. During pier construction, strictly control the amount of cement, curing agent, and water according to the construction mix ratio determined by the test. The cement slurry must be fully mixed and uniform. Ensure that the slurry required for each pile is mixed separately at one time and filtered when poured into the aggregate to prevent clumping. S15. Solidified pile testing: After all solidified piles have reached the design strength, a load plate test is conducted on the treated area. A light dynamic penetrometer is used to test the solidified soil. A certain number of drop hammers are used to strike the treated foundation surface, and the penetration depth of the drop hammers and the vibration velocity of the soil layer are recorded.

[0006] Preferably, S14 includes the following steps: S141. After the pile position indicators are accepted and qualified, drilling begins. The mud pump is started to supply slurry after the mixing head cuts into the soil. S142. The mixing head slowly cuts the soil and sprays grout evenly to sink to the designed pile bottom elevation. When the construction reaches the designed depth, the mixing head sprays grout and slowly lifts to the designed pile top elevation. The drill bit is then removed, the grout supply is stopped, and the single pile solidification construction is completed. S143. The mixing and supply of slurry must be continuous, and the slurry must be mixed evenly to ensure the curing effect.

[0007] Preferably, during the grouting process, it is necessary to check whether the grouting pipe is blocked or leaking; the grouting interval should not exceed 30 minutes.

[0008] Preferably, the dry method for pier construction includes the following steps: S21. Clear and level the surface. Use an excavator to remove the turf and humus within the survey and setting-out area. After removing the topsoil, transport it to the designated spoil disposal site for storage and level the site. S22. Laying out and positioning: Lay out the starting point, ending point, left side line, right side line, and center stake position for the construction section. Based on the surveying and layout range and the pile position layout diagram, use a 50m steel tape and RTK to determine the axis of each row of piles and the center of each pile, and mark them with lime and wooden stakes. S23. The auger is positioned for drilling and hole formation. The pile driver is positioned, the pile tip is aligned with the pile position, and the hole formation is carried out in sequence. The hole formation should be carried out slowly and at a uniform speed to avoid disturbing the surrounding soil with the drill bit. If obstacles are found during the hole formation process, they should be dealt with in time before drilling can continue. If cavities are found, they should be recorded and reported, and backfilled and compacted with mixed material. S24. Dry mixing of the mixture involves recycling, screening, and crushing all the soil extracted from the borehole. The crushed soil, cement, and curing agent are then fed into the mixing tank for mixing. The mixing time shall not be less than 95 seconds. After mixing, the mixture is sent to the pile hole for backfilling. The mixture must be used before the cement initially sets. S25. Layered compaction of piles: Use an excavator to fill the piles at specified intervals, times and quantities. Each layer of loose backfill should be 90cm thick. After three cycles, the pile elevation should be level with the ground. After each layer of backfill, the excavator should level the pile. The height difference should not be greater than 5cm. S26. Solidified pier testing: After all solidified piers have reached the design strength, a light dynamic penetrometer is used to test the solidified soil. The penetration depth of the drop hammer and the vibration velocity of the soil layer are recorded. There are no less than 3 test points in a single block or every 300m.

[0009] Preferably, S25 includes the following steps: S251. A hydraulic rammer is used, with the rammer positioned first in the center and then symmetrically around the perimeter. S252. The tamping machine should be positioned and centered smoothly, and the tamping hammer should fall freely into the bottom of the hole. S253. After filling, compaction should be done with heavy hammers and light hammers, with no less than 10 hammer blows per layer. S254. Filling and tamping are carried out alternately, filling and tamping at the same time, with uniform material distribution and uniform tamping to the design elevation. S255. The construction supervisor shall manage the quality of pile compaction, conduct regular inspections, and carefully fill in the construction records.

[0010] Preferably, step three includes the following steps: S31. Cement spreading: According to the ash dosage, the cement is evenly spread on the flat plain soil by weight ratio. After checking the area and the amount of cement, it is spread evenly with a scraper in time. S32. When mixing cement and soil, if the moisture content meets the requirements, use a road mixer to mix them in a timely manner. After mixing evenly, take samples to measure the moisture content and cement-soil ash content. S33. Secondary leveling: After the cement-soil mixture is evenly mixed, it is compacted once with a road roller, and then initially leveled again with a grader. S34. Compaction: The compaction is carried out by first stabilizing the compaction with a vibratory roller, starting with weak vibration and gradually increasing to strong vibration. The roller tracks overlap by 0.4-0.5m until there are no obvious tracks. S35. Curing: After the cement-soil compaction is completed, the compaction degree should be tested in a timely manner. Once it is qualified, the compaction should be stopped and curing should be carried out. Anti-freezing measures should be taken for cement-soil construction in winter.

[0011] Preferably, S31 includes the following steps: S311. Manual spreading: According to the spreading area of ​​each bag of cement, grid lines are laid out. Cement needs to be placed in each grid for spreading and mixing. The cement is poured on the plain soil and spread evenly using a loader and manual labor. S312, Cement Spreader: The cement spreader spreads cement using volumetric metering. Before use, the maximum spreading volume is measured and calibrated on-site. Then, the automatic control parameters are adjusted, and the vehicle speed is selected to achieve the desired spreading volume.

[0012] Preferably, after the roadbed construction in step four is completed, the settlement is observed once every 7 days, and the settlement observation is stopped if the settlement is within 2mm for two consecutive weeks.

[0013] Therefore, the present invention adopts the above-mentioned construction method of synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids. It improves the project quality through wet pier construction and dry pier construction, solves the problem of difficult construction on soft foundations, and solves the problem of uneven solidification of pier tops by manually spreading cement after leveling the pier top, while further improving the bearing capacity of the roadbed base.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 This is a flowchart of a construction method for synergistically enhancing the bearing capacity of soft soil foundation using a solidified pier and geogrid, according to the present invention. Figure 2 This is a flowchart of the wet construction method of the present invention; Figure 3 This is a flowchart of the dry construction method of the present invention. Detailed Implementation

[0016] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0018] Example Please see Figures 1-3 This invention provides a construction method for synergistically enhancing the bearing capacity of soft soil foundations using solidified piers and geogrids, comprising the following steps: Step 1: Construction preparation, including preparation and inspection of the test equipment and construction materials.

[0019] Step 2: Pier construction. Select appropriate pier treatment methods according to geological requirements. Pier construction includes dry construction and wet construction.

[0020] The geogrid composite layer in the wet-laid pier is 0.5m thick, and the piers are arranged in a rectangular shape.

[0021] The wet construction method for piers includes the following steps: S11. Clear and level the surface. Based on the soft soil treatment area, mark the construction boundary stakes in 20m sections and indicate the stake numbers. Use an excavator to remove turf and humus within the surveying and setting-out area. After removing the topsoil, transport it to the designated spoil disposal site. Backfill and compact the pits according to specifications, and level the site.

[0022] S12. Layout and Positioning: After site leveling, mark the starting point, ending point, left side line, right side line, and center stake location for each construction section. Based on the survey layout area and pile location plan, use a 50m steel tape measure and RTK (Real-Time Kinematic) to determine the axis of each row of piles and the center of each pile (center deviation ≤ 10mm). Mark these locations clearly with lime and wooden stakes to prevent damage. Lay out the pile top elevation according to the design. Simultaneously, attach the pile number from the pile location plan to bamboo stakes using bookmarks for pile location identification, facilitating construction management and data organization.

[0023] S13. Positioning of the curing mixer: Before construction, complete the acceptance inspection of cement and curing agent upon arrival at the site. After the curing mixer and slurry supply equipment are transported to the site, install and debug them, calibrate all instruments, and collect all necessary data. Once the curing mixer, slurry preparation equipment, and mud pump are all operating normally, mix the curing slurry according to the mix proportion, and then position the mixer. Align the center of the mixer drill bit with the center of the pile position, adjust the mixer to be level and stable, and mark the depth control line on the mixer's robotic arm.

[0024] S14. During pier construction, when preparing the grout, the amount of cement, curing agent, and water should be strictly controlled according to the construction mix ratio determined by the test. The amount of cement and curing agent should not be less than the design amount. The cement grout must be fully mixed and uniform. Ensure that the grout required for each pile is prepared separately at one time. A designated person should record the amount of cement and curing agent for each pile. The prepared grout should not segregate. When pouring it into the aggregate, it should be screened to prevent clumping and damage to the pump body. Before pumping the grout, the pipeline should be kept moist to facilitate grout delivery.

[0025] The cement grout must be mixed strictly according to the mix proportion. During the grouting process, the grouting pipes must be checked frequently for blockages and leaks. If the grout cannot be filled in one continuous operation or the interval exceeds 30 minutes, it must be immediately rinsed clean with water. The amount of cement and curing agent used must not be less than the design value.

[0026] The pier construction includes the following steps: S141. Before drilling begins, the supervising engineer shall be notified for inspection. After the supervising engineer confirms that the pile position and other indicators are qualified, drilling shall commence. To avoid pollution of the surrounding environment by the slurry, the mud pump shall be started to supply slurry only after the mixing head has cut into the soil.

[0027] S142. The mixing head slowly cuts the soil and uniformly sprays and mixes the grout as it sinks to the designed pile bottom elevation. After reaching the designed depth, the mixing head is slowly raised to the designed pile top elevation, the drill bit is withdrawn, and the grout supply is stopped, completing the single pile curing construction. During the construction process, the drilling and lifting speed of the mixing head must be strictly controlled, and the supply of curing grout must be proportional to the drilling progress.

[0028] S143. Grout mixing and supply must be continuous, and the grout must be mixed evenly to ensure solidification. Drilling for a 2m single pile should be controlled within 5 minutes, and lifting within 2 minutes.

[0029] S15. For the solidified pile testing, the mixer is moved to the next pile foundation, and drilling and mixing are repeated until all pile foundations within the section have undergone solidification. After all solidified piles reach their design strength, a load plate test is conducted on the treated area. A lightweight dynamic cone penetrometer is used to test the solidified soil. A certain number of drop hammers are used to strike the treated foundation surface, recording the penetration depth and vibration velocity of the soil layer. These data are analyzed to determine the bearing capacity and seismic performance of the foundation. At least three test points are required per block or every 300m.

[0030] Dry construction of piers includes the following steps: S21. Clear and level the surface. Based on the soft soil treatment area, mark the construction boundary stakes in 20m sections and indicate the stake numbers. Use an excavator to remove turf and humus within the survey and setting-out area. After removing the topsoil, transport it to the designated spoil heap for storage and level the site.

[0031] S22. Layout and Positioning: For each construction section, mark the starting point, ending point, left side line, right side line, and center stake location. Based on the survey layout area and pile layout diagram, use a 50m steel tape measure and RTK (Real-Time Kinematic) to determine the axis of each row of piles and the center of each pile (center deviation ≤ 10mm). Mark these locations clearly with lime and wooden stakes to prevent damage. Lay out the pile top elevation according to the design. Simultaneously, attach the pile numbers from the pile layout diagram to bamboo stakes using bookmarks for pile identification, facilitating construction management and data organization. After the surveyors complete the layout record, submit it to the supervising engineer for on-site review and acceptance.

[0032] S23. The auger drilling rig is positioned and drilled. The construction worker checks and verifies the pile position, ensuring the drill rod is vertical, does not move or tilt during drilling, and the pile tip is aligned with the pile position with a positioning deviation of <5cm. Drilling is carried out sequentially and continuously, with the hole diameter not less than the designed pile diameter. The hole depth is not less than the designed hole depth, with an allowable error of -5cm to +10cm. The center deviation of the hole opening is ≤5cm. During drilling, the verticality of the drill rod is checked, and any deviations are adjusted promptly to ensure the verticality of the hole is ≤1.5%. Drilling should be slow and uniform to avoid disturbing the surrounding soil with the drill bit, controlling the verticality of the drill rod to ensure that the diameter, verticality, and depth of the hole meet the design requirements. Obstacles are discovered during drilling and are dealt with promptly before drilling continues. Any cavities discovered must be recorded and reported, and backfilled and compacted with a mixture. After drilling, the quality of the pile hole is checked promptly, and measures are taken to address any deviations or shrinkage.

[0033] S24. Dry mixing of the mixture: First, use a manual-assisted excavator to recover all the soil extracted from the borehole. Screen to remove stones larger than 10cm, grass roots, etc., and then perform preliminary crushing with the excavator. Calculate the amount of cement and hardener according to the borehole volume and soil density, based on the mix proportions. The SEM-GJ-2.0 mixing hopper has a volume of 1.8m³. 3 The specific gravity of the loosely mixed and solidified soil is taken as 1.35 (testing is required), and the dosage of various proportions is calculated. The crushed soil, cement, and SES-NT-007 hardener are sequentially added to the mixing tank and mixed for at least 95 seconds. The mixing process should start slowly and gradually increase in speed, finally reaching a uniform speed. After mixing, the mixture is sent to the pile hole for backfilling. The mixture must be used before the cement initially sets.

[0034] S25. Layered compaction for pile formation: Use an excavator to fill the piles at specified intervals, times, and quantities. Each layer of loose backfill should be 90cm thick, with a compaction coefficient of 1.35, resulting in a compacted thickness of 67cm. After three cycles, the pile elevation should be level with the ground. After each layer of backfill, the excavator should level the surface, ensuring the height difference does not exceed 5cm. ① Use a hydraulic tamping hammer, operated by a designated person. The hammer should be positioned first in the center and then symmetrically around the perimeter. ② Position the tamping machine smoothly and center it, allowing the hammer to fall freely into the bottom of the hole. ③ After filling, compaction should be done with heavy but light blows, with at least 10 hammer blows per layer. ④ Alternate filling and tamping, filling and tamping simultaneously, ensuring even material distribution and uniform tamping to the design elevation. ⑤ The construction supervisor manages the pile compaction quality and conducts regular inspections.

[0035] S26. For the solidified pier testing, repeat the drilling, layered backfilling, and compaction process until all solidified piers within the section are treated. After all solidified piers reach their design strength, conduct a load plate test on the treated area. Use a lightweight dynamic cone penetrometer to test the solidified soil, striking the treated foundation surface with a certain number of drop hammers, recording the penetration depth and vibration velocity of the soil layer. Analyze these data to determine the bearing capacity and seismic performance of the foundation; at least three test points should be used per block or every 300m.

[0036] Step 3: Cement-soil modification. After the in-situ solidified pile area test is qualified, the measurement and layout are carried out again, the site is leveled and static pressure is applied, and cement is manually spread and mixed by a road mixing machine after the pier top is leveled.

[0037] S31. Cement spreading: First, draw squares on the spread subgrade with lime. Then, spread the cement evenly on the spread subgrade according to the lime dosage and weight ratio. After checking the area and the amount of cement, spread it evenly with a scraper in time.

[0038] ① Manual spreading: Based on the spreading area of ​​each bag of cement, lay out 6.5m... For a 10m grid, approximately 23 bags of cement need to be placed in each square for mortar mixing. Cement is delivered to the paving section by dump truck, unloaded directly into the marked grid, and checked for any omissions or excess. Then, the cement is poured onto the subgrade and spread evenly using a loader and manual labor.

[0039] ② Cement Spreading by a Cement Spreader: The cement spreader uses volumetric metering for cement spreading. Before use, the maximum spreading volume is measured and calibrated on-site. Then, the relevant parameters of the automatic control are adjusted, and a suitable vehicle speed is selected to achieve the required spreading volume. The spreading volume is displayed on a screen in real time. The maximum spreading width is 2.5m, and the spreading width and thickness are adjustable. The cement spreader is vehicle-mounted and can be directly connected to bulk cement tankers for loading. It has continuous operation capability. Before construction, the machine is mounted on a transport vehicle with a suitable load capacity. After construction, the equipment can be unloaded and stored separately.

[0040] S32. When mixing cement and soil, if the moisture content meets the requirements, use a road mixer to mix them promptly. After uniform mixing, take samples to test the moisture content and cement-soil ash content. If the ash content does not meet the requirements, calculate the amount of cement to be added based on the test data, spread it evenly, and mix again. At the end of mixing, if the moisture content of the mixture is insufficient, use a water truck to add water. After watering, mix again to ensure the moisture is evenly distributed in the mixture. The mixing machinery should closely follow the water truck to reduce moisture loss. During the watering and mixing process, check the moisture content of the mixture regularly. After uniform mixing, the mixture should have a consistent color, no cement lumps or uneven surfaces, and a suitable and uniform moisture content.

[0041] S33. Secondary leveling: After the cement-soil mixture is thoroughly mixed, it is compacted once with a road roller, and then initially leveled again with a grader. The grader is used to level from one side to the other, and then the road roller is used to statically compact the newly leveled section once. Special attention is paid to the leveling of the joints to ensure that the joints are smooth and flat.

[0042] S34. Compaction: A vibratory roller is used for initial stabilization, then gradually increases the speed from slow to fast, from weak to strong vibration. The roller tracks overlap by 0.4-0.5m until no obvious tracks remain. Testing personnel continuously monitor the compaction degree, which must exceed the design requirements. The entire compaction process must be completed before the retarder cement fails. After compaction, the next layer can only be constructed after passing inspection. Compaction follows the principle of starting with light pressure and progressing to heavier pressure, and from static pressure to vibratory pressure, with a 1 / 3 wheel width overlap during compaction.

[0043] S35. Curing: After the cement-soil compaction is completed, the compaction degree should be tested in a timely manner. Once it is qualified, the compaction should be stopped and curing should be carried out. Anti-freezing measures should be taken for cement-soil construction in winter.

[0044] Step 4: Settlement monitoring. Settlement monitoring boards are installed after backfilling the cement-soil section. The boards are placed approximately every 20 meters along the centerline of the access road. Settlement is monitored every 7 days after the roadbed construction is completed. If the settlement is less than 2 mm for two consecutive weeks, settlement monitoring is discontinued.

[0045] Therefore, the present invention adopts the above-mentioned construction method of synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids. It improves the project quality through wet pier construction and dry pier construction, solves the problem of difficult construction on soft foundations, and solves the problem of uneven solidification of pier top by manually spreading cement after leveling the pier top, while further improving the bearing capacity of the roadbed base.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A construction method for synergistically enhancing the bearing capacity of soft soil foundations using solidified piers and geogrids, characterized in that, Includes the following steps: Step 1: Construction preparation, including preparing and inspecting the testing equipment and construction materials; Step 2: Pier construction. Select appropriate pier treatment methods according to geological requirements. Pier construction includes dry construction and wet construction. Step 3: Cement-soil modification. After the in-situ solidified pile area test is qualified, the measurement and layout are carried out again, the site is leveled and statically compacted, and after the pier top is leveled, cement is spread manually and mixed by a road mixing machine. Step 4: Settlement monitoring. Settlement monitoring boards are installed in reverse excavation behind the cement-soil road. The settlement monitoring boards are set at the center line of the access road. Settlement is monitored every 7 days after the roadbed construction is completed.

2. The construction method for synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids according to claim 1, characterized in that: In step two, the thickness of the geogrid composite layer in the wet-method pier is 0.5m, and the pier is arranged in a rectangular shape. The wet construction method for piers includes the following steps: S11. Clear and level the surface. Use an excavator to remove the turf and humus within the survey and setting-out area. After removing the topsoil, transport it to the designated spoil disposal site. Backfill and compact the pits according to the specifications, and level the site. S12. Layout and positioning: Based on the soft soil treatment range, lay out the construction side piles in 20m sections. Lay out the starting point, ending point, left side line, right side line, and center pile position for the construction section. Based on the measurement layout range and pile position layout diagram, use a 50m steel tape and RTK to determine the axis of each row of piles and the center of each pile, and mark them with lime and wooden piles. S13. Positioning of the curing mixer: Before construction, complete the acceptance of cement and curing agent upon arrival. Mix the curing slurry according to the mix ratio. Align the center of the mixer drill bit with the center of the pile position. Adjust the mixer to be level and stable. Mark the depth control line on the mixer's mechanical arm. S14. During pier construction, the amount of cement, curing agent, and water shall be strictly controlled according to the construction mix ratio determined by the test. The cement slurry shall be fully and evenly mixed. The slurry required for each pile shall be mixed separately at one time and filtered when poured into the aggregate to prevent clumping. S15. Solidified pile testing: After all solidified piles have reached the design strength, a load plate test is conducted on the treated area. A light dynamic penetrometer is used to test the solidified soil. A certain number of drop hammers are used to strike the treated foundation surface, and the penetration depth of the drop hammers and the vibration velocity of the soil layer are recorded.

3. The construction method for synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids according to claim 2, characterized in that, S14 includes the following steps: S141. After the pile position indicators are accepted and qualified, drilling begins. The mud pump is started to supply slurry after the mixing head cuts into the soil. S142. The mixing head slowly cuts the soil and sprays grout evenly to sink to the designed pile bottom elevation. When the construction reaches the designed depth, the mixing head sprays grout and slowly lifts to the designed pile top elevation. The drill bit is then removed, the grout supply is stopped, and the single pile solidification construction is completed. S143. The slurry mixing and supply should be continuous, and the slurry should be mixed evenly to ensure the curing effect.

4. The construction method for synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids according to claim 3, characterized in that: During the grouting process, check whether the grouting pipes are blocked or leaking; the grouting interval should not exceed 30 minutes.

5. The construction method for synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids according to claim 4, characterized in that, Dry construction of piers includes the following steps: S21. Clear and level the surface. Use an excavator to remove the turf and humus within the survey and setting-out area. After removing the topsoil, transport it to the designated spoil disposal site for storage and level the site. S22. Layout and positioning: Layout the starting point, ending point, left side line, right side line, and center stake point for the construction section. Based on the measurement layout range and pile layout diagram, use a 50m steel tape and RTK to determine the axis of each row of piles and the center of each pile, and mark them with lime and wooden stakes. S23. The auger drilling rig is positioned and the hole is formed. The pile driver is positioned and the pile tip is aligned with the pile position. The hole formation sequence is carried out continuously. The hole formation drilling should be slow and uniform to avoid the drill bit disturbing the surrounding soil. If obstacles are found during the hole formation process, they should be dealt with in time before drilling construction can continue. If cavities are found, they should be recorded and reported, and backfilled and compacted with the mixed material. S24. Dry mixing of the mixture involves recycling, screening, and crushing all the soil extracted from the borehole. The crushed soil, cement, and curing agent are then fed into the mixing tank for mixing. The mixing time is no less than 95 seconds. After mixing, the mixture is sent to the pile hole for backfilling. The mixture must be used before the cement initially sets. S25. Layered compaction of piles: Use an excavator to fill the piles at specified intervals, times and quantities. Each layer of loose backfill should be 90cm thick. After three cycles, the pile elevation should be level with the ground. After each layer of backfill, the excavator should level the pile, with a height difference of no more than 5cm. S26. Solidified pier testing: After all solidified piers have reached the design strength, a light dynamic penetrometer is used to test the solidified soil. The penetration depth of the drop hammer and the vibration velocity of the soil layer are recorded. There are no less than 3 test points in a single block or every 300m.

6. The construction method for synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids according to claim 5, characterized in that, S25 includes the following steps: S251. A hydraulic rammer is used, with the rammer positioned first in the center and then symmetrically around the perimeter. S252. The tamping machine is smoothly positioned and centered, and the tamping hammer falls freely into the bottom of the hole. S253. After filling, compaction should be done with heavy hammers and light hammers, with no less than 10 hammer blows per layer. S254. Filling and tamping are carried out alternately, filling and tamping at the same time, with uniform material distribution and uniform tamping to the design elevation. S255. The construction supervisor shall manage the quality of pile compaction, conduct regular inspections, and fill in the construction record.

7. The construction method for synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids according to claim 6, characterized in that, Step three includes the following steps: S31. Cement spreading: According to the ash dosage, the cement is evenly spread on the flat plain soil by weight ratio. After checking the area and the amount of cement, it is spread evenly with a scraper in time. S32. When mixing cement and soil, if the moisture content meets the requirements, use a road mixer to mix in a timely manner. After the mixture is evenly mixed, take samples to measure the moisture content and cement-soil ash content. S33. Secondary leveling: After the cement-soil mixture is evenly mixed, it is compacted once with a road roller, and then initially leveled again with a grader. S34. Compaction: The compaction is carried out by first stabilizing the compaction with a vibratory roller, from weak vibration to strong vibration, with the roller tracks overlapping by 0.4-0.5m until there are no obvious roller tracks. S35. Curing: After the cement-soil compaction is completed, the compaction degree should be tested in a timely manner. Once it is qualified, the compaction should be stopped and curing should be carried out. Anti-freezing measures should be taken for cement-soil construction in winter.

8. The construction method for synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids according to claim 7, characterized in that, S31 includes the following steps: S311. Manual spreading: According to the spreading area of ​​each bag of cement, grid lines are laid out, cement is placed in each grid for spreading and mixing, the cement is poured on the plain soil, and a loader and manual labor are used to spread it evenly. S312, Cement Spreader: The cement spreader spreads cement using volumetric metering. Before use, the maximum spreading volume is measured and calibrated on-site. Then, the automatic control parameters are adjusted, and the vehicle speed is selected to achieve the desired spreading volume.

9. The construction method for synergistic enhancement of soft soil bearing capacity by solidified piers and geogrids according to claim 1, characterized in that: After the roadbed construction in step four is completed, the settlement should be observed once every 7 days. If the settlement is within 2mm for two consecutive weeks, the settlement observation should be stopped.

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