Cast-in-situ bored pile yellow mud retaining wall construction method for high fill gravel geology

Abstract

The invention relates to a rotary excavating cast-in-situ bored pile construction technology, in particular to a cast-in-situ bored pile yellow mud retaining wall construction method for a high-fill gravel geology. Comprising the steps that 1, pile position positioning paying-off is conducted; 2, a drilling machine is in place; step 3, burying a pile casing; 4, drilling and hole-forming yellow mud retaining wall manufacturing; 5, hole cleaning and acceptance check are conducted; step 6, manufacturing and hoisting a reinforcement cage; 7, the guide pipe is hung and placed; 8, concrete is poured; and 9, the pile casing is pulled out. The method shows the characteristics of systematicness, comprehensiveness, geological adaptability, fine control, safety, environmental protection and the like on the whole construction method, and particularly has the advantages of strong pertinence, perfect technical implementation details, strong geological adaptability, reliable wall protection effect and quality control and the like on the application of the yellow mud wall protection technology; the method becomes a bright spot in the method. According to the construction method, the construction efficiency and quality are improved, and beneficial reference is provided for cast-in-situ bored pile construction under similar geological conditions.

Description

Technical Field

[0001] The invention relates to a rotary bored cast-in-place pile construction technology, in particular to a yellow mud wall protection construction method for a bored cast-in-place pile in high-fill gravel geology. Background Art

[0002] When constructing large industrial buildings in southwest my country, we often face the challenges of complex strata and narrow sites, which makes it difficult to meet land demand. Therefore, most projects adopt the method of blasting rock mountains and backfilling crushed stones to level the site for subsequent construction. However, this high backfill crushed stone site has many problems: low soil content, loose crushed stones, easy hole collapse, and large backfill depth, which brings great difficulty to the construction of bored pile holes.

[0003] When attempting to use the mud wall protection hole technology for bored pile construction, due to the low compaction of the backfill gravel and the large cracks between the gravel, a large amount of mud will be lost during the hole formation process. At the same time, the hole wall is entirely composed of gravel, and the mud wall protection function cannot be effectively exerted.

[0004] If the traditional dry drilling method is used, the hole wall is still composed of loose gravel. During the drilling process, due to vibration, the gravel is easy to fall, which increases the risk of drill sticking, hole collapse and pile diameter shrinkage. This will not only lead to repeated operations and extend the construction period, but also when pouring concrete after drilling, due to the large gaps in the hole wall, concrete leakage is likely to occur, which has a serious impact on the quality of the pile concrete. After pouring, the filling coefficient of the pile concrete often exceeds the design value, which is not conducive to the reasonable control of the project cost. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects and to provide a method for constructing a bored cast-in-place pile yellow mud wall in high-fill gravel geology.

[0006] In order to achieve the above object, the present invention is achieved in the following ways: A method for constructing a bored cast-in-place pile yellow mud wall in high-fill gravel geology, comprising: Step 1: Pile positioning and laying out: The position of the pile foundation is laid out in the order of "from the whole to the part". During the laying process, the total station is used to accurately lay out the position of each pile point to ensure that the error of each pile point is within the specification requirements; Step 2: Drilling rig in place: Check the performance of the drilling rig in advance and debug it before construction. Then move the drilling rig to the site and put it in place. Step 3: Bury casing: The buried depth of the casing should be determined according to the geological conditions. The minimum buried depth should be greater than 2m, and it should pass through the soft grain layer of the easily collapsed hole. When burying the casing, the center position of the steel casing should be determined. The deviation between the center of the casing and the center of the pile position should not be greater than 50mm, and the inclination of the casing should not be greater than 0.5%. After the casing is in place, it should be backfilled and compacted symmetrically and evenly on all sides. When compacting, the casing should be prevented from tilting and shifting. Step 4: Drilling and forming yellow mud wall protection: During the drilling process, the footage speed is controlled according to the geological conditions: in the formation that is easy to shrink, the number of hole sweeping should be appropriately increased to prevent shrinkage; in the deep gravel backfill geology of the site, in order to prevent the quality problem of hole collapse, when drilling, the yellow mud is first backfilled to 2 to 3 meters above the hole position, and the drill bit of the rotary drilling rig is reversed. The gaps between the gravel on the hole wall can be scraped flat by the drilling pressure to flatten the clay, and the clay on the gravel hole wall is firmly bonded and flat, so as to prevent the fine stones on the hole wall from sliding off and achieve the wall protection effect; Step 5: Hole cleaning and acceptance: Step 5.1, first hole cleaning: After drilling to the designed depth, use the hole cleaning drill to clean the hole, pay close attention to the depth display value on the drilling rig computer, when the display value is the drilling depth display value, rotate 4 to 5 times in the original position to rotate the sediment at the bottom of the hole into the bucket, and then lift the rotary bucket to unload the sediment; Step 5.2, hole inspection: After cleaning the hole, use a measuring rope to measure the hole depth in time. Only after the hole depth, hole diameter and inclination are tested and qualified can the next process be entered. Before lowering the steel cage and pouring concrete, re-measure the hole depth to check whether there is any hole collapse; Step 5.3, Second hole cleaning: After the placement of the concrete conduit, re-measure the hole depth, bottom sediment and mud specific gravity; if the bottom sediment meets the design requirements, pour concrete immediately after the second hole cleaning; if the thickness of the sediment does not meet the requirements, clean the hole again; Step 6: Fabrication and hanging of steel cage: The production of steel cages should meet the requirements of the construction design drawings. The steel bars should be straight without local bends. The coiled steel bars and bent steel bars should be straightened. The spiral bars and main bars should be fixed by spot welding. The construction sequence of the steel cage is lifting, positioning, lowering, and positioning verification. Step 7: Hang the catheter: The conduit joint adopts double-threaded square buckle quick connector, and the outer diameter of the conduit joint should be at least 100mm smaller than the inner diameter of the steel cage; for piles with a diameter greater than 800mm, the conduit wall thickness should not be less than 3mm, the conduit diameter should not be less than 300mm, each section is 2-3m, the bottom pipe length should not be less than 4m, and 1-2 sections of 1-1.5m short pipes should be equipped; Step 8: pouring concrete: The slump of concrete is controlled at 18-22cm. The concrete has good workability and fluidity. Before pouring concrete, the concrete delivery pipeline and container need to be sprinkled with water to moisten them, and then waterproof facilities are installed in the filling conduit. After the storage hopper is full of concrete, start pouring underwater concrete. Sufficient initial concrete pouring volume should be ensured. After the first batch of concrete falls, concrete should be poured continuously. During the pouring process, the buried depth of the conduit should be controlled at 2-6m. The elevation of the pile top to be poured should be controlled to be no less than 1.0m higher than the design elevation to ensure the strength of the concrete. The excess pile head must be chiseled off to ensure that there is no loose layer at the pile head. Step 9: Pull out the casing: After the concrete pouring is completed and the initial setting is completed, the casing should be pulled out in time by a crane. The pulling-out process should ensure continuity and be completed in one go.

[0007] In step 1 of the above-mentioned method for constructing bored cast-in-place piles and yellow mud wall in high fill gravel geology, after the pile positions are determined, the piles in the same row are spaced apart to form piles; when the elevation of the borehole is staked out, the staked out elevation should be reviewed in time.

[0008] In step 2 of the above-mentioned method for constructing bored cast-in-place pile yellow mud wall in high fill gravel geology, small-size gravel is used to level the uneven part of the pile position to ensure that the drilling rig is stable and does not sink during operation, and the area near the pile position is ensured to be flat. The drilling rig is driven next to the pile position, with the center of the drill bit facing the pile position marking point. The drilling rig is moved into position using a self-propelled mobile system, and the alignment error between the drill bit and the pile position should be less than 2 mm.

[0009] In step 3 of the above-mentioned method for constructing bored pile yellow mud wall in high fill gravel geology, the casing is made of steel casing, which is made of steel plate with a thickness of not less than 10 mm. The inner diameter of the casing should be 100 mm larger than the diameter of the drill bit, and the diameter error of the steel casing should be less than 10 mm.

[0010] In step 4 of the method for constructing bored pile yellow mud wall in high-fill gravel geology, the yellow mud is backfilled into the hole by utilizing its high viscosity, plasticity and density and then scraped flat by the rotary drilling rig drill bit, so that the clay on the gravel hole wall is firmly bonded and flat, thereby achieving the effect of wall protection; wherein, the drill bit reversal force and hole sweeping times should be adjusted according to different geological effects to ensure the quality and effect of the wall protection. In the actual implementation process, The above-mentioned bored cast-in-place pile yellow mud wall construction method for high-fill gravel geology proposed by the present invention has the following advantages as a whole: 1. Systematic and comprehensive: This method covers the entire construction process from pile location and line setting to casing extraction. Each step is closely linked to form a systematic and comprehensive construction plan. This systematic planning ensures the continuity and efficiency of the construction process.

[0011] 2. Geological adaptability: Taking into account the particularity of high-fill gravel geology, this method conducts a full investigation and analysis of the geological conditions before construction, and flexibly adjusts construction parameters such as drilling speed and casing burial depth according to geological changes during the construction process to meet the needs of different geological conditions.

[0012] 3. Fine control: This method emphasizes fine control over the construction process, such as using a total station to accurately stake out pile locations, strictly controlling the deviation between the center of the casing and the center of the pile, and real-time monitoring of drilling depth, to ensure construction accuracy and quality.

[0013] 4. Safety and environmental protection: During the construction process, this method focuses on safety and environmental protection measures, such as checking the performance status of the drilling rig, preventing the casing from deflecting and shifting, controlling the slump of concrete, etc., to reduce safety hazards and environmental pollution during the construction process.

[0014] Furthermore, on the basis of the above, the application of the yellow mud wall protection technology in the present invention has also been deepened and innovated, achieving new technological breakthroughs and technical achievements. Specifically, the deepening of the yellow mud wall protection technology in the present invention is: 1. Strong targeting: The yellow mud wall protection technology was designed and adjusted specifically to address the problem of hole wall stability in bored pile construction under high-fill gravel geological conditions. In high-fill gravel geology, the hole wall is prone to collapse, and the yellow mud wall protection technology effectively enhances the stability of the hole wall by backfilling yellow mud and utilizing its viscous properties.

[0015] 2. Technical implementation details: Selection of yellow soil: Select yellow soil with moderate viscosity and fine particles to ensure that it can fit closely to the hole wall and form a stable protective wall layer.

[0016] Backfill method and position: The yellow mud needs to be backfilled to a certain height above the position in the hole (such as 2 to 3m) to ensure that the yellow mud can fully cover the hole wall.

[0017] Drilling pressure and reverse scraping: During the drilling process, the drilling pressure is used to scrape the clay soil flat, so that the clay on the gravel hole wall is firmly bonded and flat, preventing fine stones from slipping off the hole wall.

[0018] 3. Geological adaptability: The implementation of the yellow mud wall protection technology needs to be adjusted according to the geological conditions. For example, in the strata that are easy to shrink, it is necessary to increase the number of borehole sweeping to prevent shrinkage; in the deep gravel backfill geology of the site, special attention needs to be paid to prevent the quality problem of hole collapse.

[0019] The key to the successful implementation of the yellow mud wall protection technology lies in the quality control of the wall protection effect; during the construction process, the stability of the hole wall and the thickness of the wall protection layer should be closely monitored to ensure that the wall protection effect meets the design requirements. At the same time, the yellow mud wall protection layer also needs to be maintained and maintained to extend its service life. In this method, such as in the implementation stage of the yellow mud wall protection technology, the importance of the wall protection effect is emphasized: by selecting yellow mud with moderate viscosity and fine particles, and backfilling to a certain height above the hole position (such as 2 to 3m), it can be ensured that the yellow mud can fit the hole wall tightly and form a stable wall protection layer. And during the drilling process, the drilling pressure is used to scrape the clay soil flat, so that the clay on the gravel hole wall is firmly bonded and flat, which is also to enhance the stability of the wall protection layer and improve the wall protection effect. At the same time, in the formation that is easy to shrink, the number of hole sweeping is appropriately increased to prevent shrinkage, etc., so that the yellow mud wall protection effect can be maintained and the quality control can be achieved.

[0020] In summary, the yellow mud wall protection construction method for bored piles in high-fill gravel geology proposed in the present invention shows the characteristics of systematicity and comprehensiveness, geological adaptability, fine control, safety and environmental protection in the overall construction method. In terms of individual technical characteristics, the yellow mud wall protection technology has the advantages of strong pertinence, perfect technical implementation details, strong geological adaptability, and reliable wall protection effect and quality control. This construction method not only improves construction efficiency and quality, but also provides a useful reference and reference for bored pile construction under similar geological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the yellow mud wall protection construction method of bored cast-in-place piles in high fill gravel geology shown in the present invention. DETAILED DESCRIPTION

[0022] The technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments in the embodiments of the present application are within the scope of protection requested by the present application.

[0023] Taking a certain area in southwest my country as an example, the bored cast-in-place pile yellow mud wall construction method for high fill gravel geology proposed by the present invention is further explained below: 1. Project Overview The project site is located in the southwest of my country. The geological conditions are high-fill gravel geology, and bored pile construction is required. The construction requires ensuring the stability of the hole wall and preventing collapse. After comprehensive consideration of various factors, it was decided to use yellow mud wall protection technology.

[0024] 2. Construction Preparation 1. Site leveling and surveying and setting out: Use a total station to perform precise surveying and setting out, mark the center of the pile position, and ensure that the error does not exceed 5mm.

[0025] The construction site should be carefully leveled to ensure that the machinery can move and operate smoothly without bumps.

[0026] 2. Casing burial: The casing is made of steel plate with a thickness of not less than 10mm, and the inner diameter is 100mm larger than the designed pile diameter.

[0027] Before burying the casing, dig a casing pit first, and the bottom of the pit should be flat and solid.

[0028] The buried depth of casing is determined according to the geological conditions, generally not less than 1.5m, and 300mm above the ground, compacted with clay.

[0029] 3. Drilling tool selection and data determination 1. Drilling rig selection: The XY-200 hydraulic core drilling rig is selected, which is efficient and stable and suitable for high-fill gravel geology.

[0030] 2. Drilling tool data: Drill bit diameter: Determined according to the designed pile diameter. For example, if the designed pile diameter is 1000mm, the drill bit diameter should be 980mm.

[0031] Speed: Adjust according to geological conditions, generally between 15-25 revolutions per minute. In hard soil layers, the speed can be appropriately reduced; in soft soil layers, the speed can be appropriately increased.

[0032] Driving speed: Control according to geological conditions and drilling pressure to avoid excessive drilling speed that may cause hole wall collapse. Generally, the drilling time per meter is controlled at 2-3 minutes.

[0033] 4. Implementation of yellow mud wall protection 1. Yellow mud selection: Choose yellow clay with moderate viscosity and fine particles. Its moisture content should be controlled between 15% and 20% to ensure that it can fit closely to the hole wall and form a stable wall protective layer.

[0034] 2. Implementation process of yellow mud wall protection: Backfill with yellow mud: During the drilling process, stop drilling every 2m and backfill with yellow mud to 2.5m above the hole position. When backfilling, spread it evenly in the hole to avoid local accumulation.

[0035] Scraping and compaction: Use drilling pressure to scrape the yellow mud flat so that it fits tightly against the hole wall. When scraping, it should be done slowly to avoid impacting the hole wall. After compaction, use a measuring rope to check the thickness and uniformity of the yellow mud wall.

[0036] Inspection and maintenance: Check the wall protection layer regularly. If cracks or peeling are found, repair and maintenance should be carried out in time. When repairing, yellow mud slurry can be used for smearing and compaction.

[0037] 5. Drilling and hole cleaning 1. Drilling: Drilling should be carried out according to the hole diameter and hole depth required by the design. During the drilling process, the drilling speed and penetration depth should be adjusted according to the geological conditions to avoid hole wall collapse.

[0038] During drilling, the drilling depth, time, speed and other parameters should be recorded for subsequent analysis and adjustment.

[0039] 2. Cleaning holes: After the drilling is completed, the hole is cleaned. First, the positive circulation hole is used to clean the remaining gravel and soil in the hole. Then the reverse circulation hole is used to clean the bottom sediment completely.

[0040] After cleaning the hole, check the thickness of the sediment at the bottom of the hole to ensure that it does not exceed the design thickness (generally not more than 50mm).

[0041] 6. Fabrication and hoisting of steel cage 1. Steel cage production: Make the steel cage according to the design requirements, and ensure that the steel bar specifications, quantity, length, etc. meet the standards. The diameter of the steel cage should be 20-30mm smaller than the designed pile diameter so that it can be smoothly placed in the hole.

[0042] When making the steel cage, the steel bars should be firmly connected and the welding quality should be reliable. At the same time, protective layer pads should be set on the steel cage to ensure that the thickness of the concrete protective layer meets the design requirements.

[0043] 2. Lifting of steel cage: Before hoisting the steel cage into the hole, check whether the diameter, length and verticality of the steel cage meet the requirements.

[0044] When hoisting, it should be done slowly to avoid collision with the hole wall. After the steel cage is placed in the hole, it should be ensured to be centered and firmly fixed. Steel pipes or steel bars can be used for support and fixing.

[0045] 7. Pouring concrete 1. Concrete preparation: Select concrete that meets the design requirements and ensure that the slump, strength and other indicators meet the requirements. The slump of concrete is generally controlled between 180-220mm.

[0046] When preparing concrete, the quality and mix ratio of raw materials should be strictly controlled. At the same time, concrete should be sampled and tested regularly to ensure that its quality meets the design requirements.

[0047] 2. Pouring concrete: The conduit method is used for underwater concrete pouring. The conduit should be a steel pipe with an inner diameter of not less than 250mm, and its length should be determined according to the hole depth.

[0048] Before pouring, check whether the sealing and connection of the conduit are firm. At the same time, a water stopper should be placed in the conduit to prevent the concrete from mixing with water.

[0049] When pouring, the concrete should be poured continuously and evenly to avoid interruption. The pouring speed should be controlled between 2-3m³ per minute. At the same time, the rise of the concrete surface in the hole should be observed at any time to ensure that the concrete fills the entire hole.

[0050] After pouring is completed, the guide tube should be pulled out and the height of the concrete surface should be checked to see if it meets the design requirements. If not, additional pouring should be carried out in time.

[0051] 8. Construction Monitoring and Acceptance 1. Construction monitoring: During the construction process, real-time monitoring should be carried out on the hole wall stability, wall protection effect, drilling speed, etc. If any abnormal situation is found, timely measures should be taken to deal with it.

[0052] At the same time, various parameters and data during the construction process should be recorded for subsequent analysis and summary.

[0053] 2. Acceptance: After the construction is completed, acceptance work should be carried out to check whether the pile position deviation, hole diameter, hole depth, concrete strength and other indicators meet the design requirements.

[0054] During acceptance, professional testing equipment and instruments should be used for measurement and testing. At the same time, relevant units and experts should be invited to conduct acceptance and evaluation. Furthermore, in the above-mentioned method for bored pile yellow mud wall construction in high-fill gravel geology, the yellow mud wall technology plays a vital role. In order to ensure the reliable implementation of the yellow mud wall technology, a method for determining the composition of the yellow mud wall and the selection of drilling tool parameters is proposed. Based on the following formula and after conducting effective experiments to obtain relevant empirical data, it is beneficial to improve the success rate of the composition of the yellow mud wall and the selection of drilling tool parameters: 1. Yellow mud wall protection ingredients The main components of yellow mud wall protection include yellow mud and water. In order to optimize the wall protection effect, it is necessary to determine the appropriate water content W. The water content W is defined as the ratio of the mass of water to the mass of yellow mud, that is: Through experiments and experience, the optimal moisture content range can be determined to ensure that the yellow mud retaining wall has sufficient strength and stability.

[0055] 2. Drilling tool debugging The debugging of drilling tools mainly includes the adjustment of the rotation speed n and the feed speed v. The rotation speed n affects the drilling efficiency and the stability of the yellow mud wall, while the feed speed v affects the drilling depth and speed. In order to obtain the best drilling effect, the rotation speed and feed speed of the drilling tool need to be finely debugged according to the geological conditions and construction requirements.

[0056] In order to establish the relationship between the yellow mud wall component and the drilling tool debugging, it is assumed that the strength σ of the yellow mud wall has the following relationship with the water content W and the drilling tool speed n: Among them, a, b and c are empirical coefficients that need to be determined through experiments. This formula reflects the nonlinear relationship between the strength of the yellow mud wall and the water content and the drilling speed.

[0057] At the same time, the thickness T of the yellow mud wall and the feed speed v and time t of the drilling tool have the following relationship: Where d is the empirical coefficient, which represents the thickness of the yellow mud wall formed by the drilling tool feeding per unit time. This formula reflects the linear relationship between the thickness of the yellow mud wall and the drilling tool feeding speed and time.

[0058] In actual construction, in order to obtain the best yellow mud wall protection effect and drilling efficiency, it is necessary to comprehensively consider geological conditions, construction requirements, drilling tool types, and the relationship between yellow mud wall protection components and drilling tool debugging. Through experiments and experience accumulation, construction parameters can be continuously optimized to improve construction quality and efficiency.

[0059] It can be seen from the above embodiments that the "a method for constructing a bored cast-in-place pile yellow mud wall in high-fill gravel geology" proposed in the present invention has significant advantages and important significance in engineering applications, which are: 1. Advantages 1. Improve construction efficiency: This method uses advanced rotary drilling rigs (such as the XY-200 hydraulic core drilling rig) to quickly and accurately complete drilling operations, greatly improving construction efficiency.

[0060] The yellow mud wall protection technology reduces the risk of hole collapse during the drilling process, avoids repeated drilling and repairs, and further shortens the construction period.

[0061] 2. Enhance the bearing capacity of pile foundation: The combination of bored cast-in-place piles and yellow mud retaining wall effectively utilizes the stress characteristics of the soil around the piles and significantly enhances the bearing capacity of the pile foundation.

[0062] The compact layer formed by the yellow mud retaining wall can increase the friction resistance on the pile side and improve the pile body's ability to resist pull-out and horizontal loads.

[0063] 3. Reduce construction costs: Compared with traditional construction methods, this method reduces the reliance on special tools or mechanical equipment and reduces construction costs.

[0064] Yellow mud is a wall protection material that is low-cost and easy to obtain, further reducing material costs.

[0065] 4. Improve engineering safety: This method reduces the risk of safety accidents such as hole collapse and landslides that may occur during the construction process through stable drilling and yellow mud wall protection technology.

[0066] Bored piles themselves have high earthquake resistance and deformation resistance, which helps to improve the safety of the overall project.

[0067] 5. Environmental protection and energy saving: The yellow mud wall protection technology reduces the waste residue and wastewater generated during the drilling process and reduces the impact on the environment.

[0068] This method does not require large-scale excavation and blasting, reduces noise and vibration pollution, and meets the requirements of environmental protection and energy conservation.

[0069] 2. Significance 1. Promote engineering technology innovation: The successful application of this method has promoted the innovation and development of bored pile construction technology and provided a new solution for engineering construction under similar geological conditions.

[0070] 2. Improve project quality: Through sophisticated construction processes and strict quality control, this method can ensure the construction quality of bored cast-in-place piles and improve the stability and durability of the overall project.

[0071] 3. Expand the scope of application: This method is not only applicable to high-fill gravel geology, but can also be applied to engineering construction under other complex geological conditions, such as soft soil, hard rock, etc.

[0072] 4. Promoting sustainable development: This method meets the requirements of environmental protection and energy conservation, helps promote the sustainable development of the construction industry, and achieves the coordination and unity of economic benefits, social benefits and environmental benefits.

[0073] The above are only embodiments provided for the present application and are not intended to limit the present application. Although the present application is described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for constructing a bored pile yellow mud wall in high-fill gravel geology, characterized by: include Step 1: Pile positioning and laying out: The position of the pile foundation is laid out in the order of "from the whole to the part". During the laying process, the total station is used to accurately lay out the position of each pile point to ensure that the error of each pile point is within the specification requirements; Step 2: Drilling rig in place: Check the performance of the drilling rig in advance and debug it before construction. Then move the drilling rig to the site and put it in place. Step 3: Bury casing: The buried depth of the casing should be determined according to the geological conditions. The minimum buried depth should be greater than 2m, and it should pass through the soft grain layer of the easily collapsed hole. When burying the casing, the center position of the steel casing should be determined. The deviation between the center of the casing and the center of the pile position should not be greater than 50mm, and the inclination of the casing should not be greater than 0.5%. After the casing is in place, it should be backfilled and compacted symmetrically and evenly on all sides. When compacting, the casing should be prevented from tilting and shifting. Step 4: Drilling and forming yellow mud wall protection: During the drilling process, the footage speed is controlled according to the geological conditions: in the formation that is easy to shrink, the number of hole sweeping should be appropriately increased to prevent shrinkage; in the deep gravel backfill geology of the site, in order to prevent the quality problem of hole collapse, when drilling, the yellow mud is first backfilled to 2 to 3 meters above the hole position, and the drill bit of the rotary drilling rig is reversed. The gaps between the gravel on the hole wall can be scraped flat by the drilling pressure to flatten the clay, and the clay on the gravel hole wall is firmly bonded and flat, so as to prevent the fine stones on the hole wall from sliding off and achieve the wall protection effect; Step 5: Hole cleaning and acceptance: Step 5.1, first hole cleaning: After drilling to the designed depth, use the hole cleaning drill to clean the hole, pay close attention to the depth display value on the drilling rig computer, when the display value is the drilling depth display value, rotate 4 to 5 times in the original position to rotate the sediment at the bottom of the hole into the bucket, and then lift the rotary bucket to unload the sediment; Step 5.2, hole inspection: After cleaning the hole, use a measuring rope to measure the hole depth in time. Only after the hole depth, hole diameter and inclination are tested and qualified can the next process be entered. Before lowering the steel cage and pouring concrete, re-measure the hole depth to check whether there is any hole collapse; Step 5.3, Second hole cleaning: After the placement of the concrete conduit, re-measure the hole depth, bottom sediment and mud specific gravity; if the bottom sediment meets the design requirements, pour concrete immediately after the second hole cleaning; if the thickness of the sediment does not meet the requirements, clean the hole again; Step 6: Fabrication and hanging of steel cage: The production of steel cages should meet the requirements of the construction design drawings. The steel bars should be straight without local bends. The coiled steel bars and bent steel bars should be straightened. The spiral bars and main bars should be fixed by spot welding. The construction sequence of the steel cage is lifting, positioning, lowering, and positioning verification. Step 7: Hang the catheter: The conduit joint adopts double-threaded square buckle quick connector, and the outer diameter of the conduit joint should be at least 100mm smaller than the inner diameter of the steel cage; for piles with a diameter greater than 800mm, the conduit wall thickness should not be less than 3mm, the conduit diameter should not be less than 300mm, each section is 2-3m, the bottom pipe length should not be less than 4m, and 1-2 sections of 1-1.5m short pipes should be equipped; Step 8: pouring concrete: The slump of concrete is controlled at 18-22cm. The concrete has good workability and fluidity. Before pouring concrete, the concrete delivery pipeline and container need to be sprinkled with water to moisten them, and then waterproof facilities are installed in the filling conduit. After the storage hopper is full of concrete, start pouring underwater concrete. Sufficient initial concrete pouring volume should be ensured. After the first batch of concrete falls, concrete should be poured continuously. During the pouring process, the buried depth of the conduit should be controlled at 2-6m. The elevation of the pile top to be poured should be controlled to be no less than 1.0m higher than the design elevation to ensure the strength of the concrete. The excess pile head must be chiseled off to ensure that there is no loose layer at the pile head. Step 9: Pull out the casing: After the concrete pouring is completed and the initial setting is completed, the casing should be pulled out in time by a crane. The pulling-out process should ensure continuity and be completed in one go.

2. The method for constructing a bored pile yellow mud wall in high-fill gravel geology according to claim 1 is characterized by: In step 1, after the pile positions are determined, the piles in the same row are spaced apart to form piles; when the elevation of the drilling holes is staked out, the staked out elevation should be reviewed in a timely manner.

3. The method for constructing a bored pile yellow mud wall in high-fill gravel geology according to claim 1 is characterized by: In step 2, use small-size gravel to smooth the uneven areas of the pile position to ensure that the drill rig is stable and does not sink during operation, and ensure that the area near the pile position is flat. Drive the drill rig to the pile position, with the center of the drill bit facing the pile position marking point. Use the self-propelled mobile system to move the drill rig into position, and the alignment error between the drill bit and the pile position should be less than 2mm.

4. The method for constructing a bored pile yellow mud wall in high-fill gravel geology according to claim 1 is characterized by: In step 3, the casing is made of a steel casing, which is made of a steel plate with a thickness of not less than 10 mm. The inner diameter of the casing should be 100 mm larger than the diameter of the drill bit, and the diameter error of the steel casing should be less than 10 mm.

5. The method for constructing a bored pile yellow mud wall in high-fill gravel geology according to claim 1 is characterized by: In step 4, the yellow mud is backfilled into the hole due to its high viscosity, plasticity and density, and is then scraped and leveled by the rotary drilling rig drill bit, so that the clay on the gravel hole wall is firmly bonded and leveled, thereby achieving the effect of wall protection; the drill bit's reversal force and the number of hole sweeps should be adjusted according to different geological effects to ensure the quality and effect of the wall protection.

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