Occlusive pile construction method based on virtual soil-cement paste solidified body

Abstract

The invention discloses a secant pile construction method based on a virtual soil-cement paste solidified body, and relates to the technical field of civil engineering foundation pit supporting, the secant pile construction method comprises the following steps: firstly obtaining parameters such as a stratum, preparing materials and adjusting equipment, constructing a pile B and a pile A, processing a special stratum, and repeatedly constructing to form a continuous secant pile wall body in sequence after detection; the method has the advantages that the solidified body is prepared through resource utilization of piling virtual soil and cement paste to replace traditional super-retarding concrete, the defect that cost is high due to the fact that a traditional material system depends on a high-price retarder is overcome, the virtual soil is recycled, outward transportation and disposal cost is reduced, bentonite and fly ash are doped into the cement paste, the use amount of a cementing material is reduced, and the cost is reduced. The material cost of the B pile per cubic meter is reduced by 40%-50%, the dosage of admixtures such as a retarder is reduced, the comprehensive cost is saved by 30% or above, meanwhile, the initial setting waiting time of the B pile is shortened, the pile forming period is shortened to 8-12 hours from 24-48 hours, the overall construction period is shortened by 15%-20%, and the construction economy and efficiency are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit support in civil engineering, in particular to a occlusal pile construction method based on a virtual soil-cement slurry solidified body. Background Art

[0002] In the field of civil engineering foundation pit support, interlocking piles, as a highly effective water-stopping and earth-retaining structure, are widely used in projects such as deep foundation pits for high-rise buildings, underground integrated pipeline corridors, and rail transit. Their core principle is to form a continuous curtain through the interlocking of adjacent piles. The piles' integrity and impermeability block the path of groundwater seepage and bear the lateral earth pressure during foundation pit excavation, thereby ensuring the safety of foundation pit construction and the stability of the surrounding environment. Traditional interlocking pile technology typically adopts an alternating "soft pile + hard pile" construction model, where soft piles are often constructed using plain concrete (such as super-slow-setting concrete) and hard piles using reinforced concrete. The partial overlap between the piles achieves both water-stopping and earth-retaining functions. With the acceleration of urbanization, deep foundation pit projects are placing higher demands on the safety, economy, and construction efficiency of support structures. In construction practice, interlocking piles must adapt to diverse geological conditions, including complex strata such as soil, sand, gravel, and rock, while also meeting the resource conservation and environmental protection requirements of green construction. The existing technology has certain defects. First, the traditional interlocking pile B pile relies on super-slow-setting concrete, which requires a large amount of expensive retarder, high material cost, and a 24-48 hour waiting time for initial setting, resulting in a long construction period and low efficiency. Second, the traditional process is prone to hole collapse and segregation in complex strata, and the residual loose soil affects the quality, requiring additional reinforcement and hole cleaning. The construction risk is high and the stability is poor. Therefore, we propose an interlocking pile construction method based on a loose soil-cement slurry solid body. Summary of the Invention

[0003] The purpose of the present invention is to provide a construction method of an interlocking pile based on a virtual soil-cement slurry solidified body.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solution: a construction method of an interlocking pile based on a virtual soil-cement slurry solidified body, comprising a construction method, wherein the construction method comprises the following steps: Step 1: Use a combination of drilling and geophysical exploration to obtain the target site's stratigraphic parameters and design pile parameters. Establish a system for collecting and pre-processing loose soil, remove impurities, and temporarily store it. Then, prepare cement slurry and debug construction equipment. Step 2: After the drilling rig is in place, start the forward rotation and drill down to mix. While mixing, inject high-pressure cement slurry to mix the cement slurry and loose soil evenly. After mixing to the designed depth, lift it up and mix it in the reverse direction to the ground to complete a soft pile. Step 3: After grouting is completed, let the solidified body stand for initial solidification, and then pull out the casing at a uniform speed to form pile B; Step 4: Before the soft piles begin to set, use the drill bit of a long screw pile driver to cut adjacent soft piles and drill down to the bottom of the hole. Then, lift the drill upwards and use a concrete pump to inject superfluid concrete from the center of the drill pipe to the bottom of the hole and onto the ground. Then, use a vibrator to vibrate the concrete and insert the steel cage to form an A pile. Step 5: Targeted construction treatment for special strata: For sandy and permeable strata, pre-reinforcement is carried out before B pile construction; for gravel strata, casing optimization is carried out; for moderately weathered rock strata, crushing technology is used to form piles; Step 6: Perform quality inspection on pile A and repeat the construction in alternating order to form a continuous interlocking pile wall.

[0005] As a further solution of the present invention: in the step one, a method combining drilling and geophysical exploration is used to obtain the stratigraphic parameters of the target site, including soil layer distribution, groundwater level, rock strength and permeability. The pile length, pile diameter and inter-pile bite thickness are designed accordingly, and a loose soil collection and pretreatment system is established. The loose soil generated by the pile driving construction is sieved through a 20mm-25mm sieve hole to remove impurities, and temporarily stored after removing the impurities. Subsequently, cement slurry is prepared and formulated at a water-cement ratio of 0.4-0.6. 5%-10% of bentonite and fly ash are added to enhance cohesion and impermeability. The grouting pump, vibrating equipment and casing drilling rig are debugged simultaneously to ensure that the equipment parameters meet the construction requirements.

[0006] As a further solution of the present invention: in the step 2, after the drilling rig is in place, the casing is pressed down section by section to the designed depth, and the verticality deviation of the casing is ensured to be ≤3‰ by real-time monitoring through the inclinometer. The soil is taken by a grab bucket, and the sieved loose soil is simultaneously transported to the mixing tank, mixed with the prepared cement slurry at a volume ratio of 1:1-1:1.5, and stirred to form a uniform plastic solidified body. The grouting pump is started, and the loose soil-cement slurry solidified body is injected into the casing through the high-pressure grouting pipe. The grouting pressure is controlled at 0.3MPa-0.5MPa, and a vibrating rod with a frequency of 50Hz-60Hz is used for segmented vibration. The vibration time of each segment is 1min-2min, so that the filling coefficient of the solidified body is ≥1.1.

[0007] As a further solution of the present invention: in the step three, after the grouting of the soft pile B is completed, it is allowed to stand for 2h-3h to allow the solidified body to initially solidify. During this period, the initial setting state of the solidified body is monitored. After the solidified body has the target plastic strength, the casing is pulled out at a uniform speed. The pulling-out speed is controlled at 1m / min-2m / min to avoid damage to the solidified body structure due to too fast pulling-out, so as to form a complete pile body of B. The compressive strength of the pile body after final setting must reach C10-C15, and the anti-seepage grade must be ≥P6.

[0008] As a further solution of the present invention: in the step 4, within 8h-12h before the initial setting of the B pile solid body, the long screw pile driver is positioned between adjacent B piles, and the cutting device is started to cut the adjacent B pile solid bodies, and the cutting depth reaches the designed pile length, so that the bite amount between the piles is 200mm-300mm, and the split steel cage is hoisted, with the main reinforcement diameter of the steel cage ≥16mm and the stirrup spacing 200mm. The steel cage is precisely positioned by the guide frame to make the thickness of the protective layer of the steel cage uniform and the verticality deviation ≤3‰.

[0009] As a further solution of the present invention: in the step five, for sand layers and permeable strata, high-pressure rotary jet piles with a diameter of 600mm-620mm are used for pre-reinforcement before the construction of B piles, and two rows are constructed at a spacing of 0.8m-0.9m to form a water stop ring. The casing wall thickness is selected to be ≥20mm, and the sinking speed is ≤0.3m / min. For pebble layers, a roller drill bit (torque ≥200kN·m) is used to penetrate the pebble layer, and the casing wall thickness is increased to 25mm-27mm. For moderately weathered rock layers, an impact hammer with an impact force of ≥300kN is used to crush the rock layer, and the casing is followed until it is embedded in the complete rock layer for ≥1.0m. The crushed rock chips can replace part of the loose soil after screening for the preparation of the solidified body.

[0010] As a further solution of the present invention: in step six, after the concrete of pile A has finally set, the low-strain method is used to detect the integrity of the pile body to ensure that the proportion of Class I piles is ≥90%, and multiple piles are continuously operated in an alternating order of "B pile → A pile → B pile", and steps two to six are repeated until the construction of all the interlocking piles is completed to form a continuous water-stopping and supporting wall.

[0011] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are: 1. The present invention utilizes pile driving soil and cement slurry to prepare a solidified body to replace traditional super-slow setting concrete, thus solving the defect of high cost caused by dependence on expensive retarder in traditional material system. The recycling of soil reduces transportation and disposal costs. The addition of bentonite and fly ash to cement slurry reduces the amount of cementitious materials used. The material cost of B pile per cubic meter is reduced by 40%-50%, the amount of admixtures such as retarder is reduced, and the comprehensive cost is saved by more than 30%. At the same time, the waiting time for the initial setting of B pile is shortened, and the pile formation cycle is shortened from 24-48 hours to 8-12 hours, which reduces the backlog of multiple pile operation processes and shortens the overall construction period by 15%-20%, significantly improving the economy and efficiency of construction. 2. The present invention solves the defects of unstable pile quality and high construction risk of traditional interlocking piles in complex strata by optimizing the construction process of loose soil-cement slurry solidification body and special stratum treatment technology. The solidification body is fully mixed by high-pressure grouting and high-frequency vibration to eliminate quality risks such as concrete segregation and loose soil residue. The pile body anti-seepage grade is ≥ P6, which meets the water-stopping requirements of deep foundation pits. High-pressure rotary jet piles are used to pre-reinforce the sand layer to form a water-stop ring. The pebble layer is optimized and enhanced in stiffness by casing. The rock layer is crushed by impact technology and followed by casing to effectively avoid hole wall collapse and cement slurry loss, significantly improve the stability of piles in complex strata, reduce the probability of hole collapse and rework, and ensure the continuity of the water-stop curtain and structural safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the method steps in an embodiment of the present invention. DETAILED DESCRIPTION

[0013] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0014] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0015] Please see the attached Figure 1 The present invention is based on a construction method of an interlocking pile of a virtual soil-cement slurry solidified body, including a construction method, and the construction method includes the following steps: Step 1: Use a combination of drilling and geophysical exploration to obtain the target site's stratigraphic parameters and design pile parameters. Establish a system for collecting and pre-processing loose soil, remove impurities, and temporarily store it. Then, prepare cement slurry and debug construction equipment. Step 2: After the drilling rig is in place, start the forward rotation and drill down to mix. While mixing, inject high-pressure cement slurry to mix the cement slurry and loose soil evenly. After mixing to the designed depth, lift it up and mix it in the reverse direction to the ground to complete a soft pile. Step 3: After grouting is completed, let the solidified body stand for initial solidification, and then pull out the casing at a uniform speed to form pile B; Step 4: Before the soft piles begin to set, use the drill bit of a long screw pile driver to cut adjacent soft piles and drill down to the bottom of the hole. Then, lift the drill upwards and use a concrete pump to inject superfluid concrete from the center of the drill pipe to the bottom of the hole and onto the ground. Then, use a vibrator to vibrate the concrete and insert the steel cage to form an A pile. Step 5: Targeted construction treatment for special strata: For sandy and permeable strata, pre-reinforcement is carried out before B pile construction; for gravel strata, casing optimization is carried out; for moderately weathered rock strata, crushing technology is used to form piles; Step 6: Perform quality inspection on pile A and repeat the construction in alternating order to form a continuous interlocking pile wall.

[0016] In one embodiment of the present invention: In step one, a method combining drilling and geophysical exploration is used to obtain the stratigraphic parameters of the target site, including soil layer distribution, groundwater level, rock strength and permeability. The pile length, pile diameter and inter-pile bite thickness are designed accordingly, and a loose soil collection and pretreatment system is established. The loose soil generated by the pile driving construction is sieved through a 20mm-25mm sieve to remove impurities, and temporarily stored after removing the impurities. Subsequently, cement slurry is prepared and formulated at a water-cement ratio of 0.4-0.6. 5%-10% of bentonite and fly ash are added to enhance cohesion and impermeability. The grouting pump, vibrating equipment and casing drilling rig are debugged simultaneously to ensure that the equipment parameters meet the construction requirements.

[0017] In one embodiment of the present invention: in step 2, after the drilling rig is in place, the casing is pressed down section by section to the designed depth, and the verticality deviation of the casing is ensured to be ≤3‰ by real-time monitoring with an inclinometer. A grab bucket is used to take soil, and the sieved loose soil is simultaneously transported to a mixing tank, mixed with the prepared cement slurry at a volume ratio of 1:1-1:1.5, and stirred to form a uniform plastic solidified body. The grouting pump is started, and the loose soil-cement slurry solidified body is injected into the casing through a high-pressure grouting pipe. The grouting pressure is controlled at 0.3MPa-0.5MPa, and a vibrating rod with a frequency of 50Hz-60Hz is used for segmented vibration, and the vibration time of each segment is 1min-2min, so that the filling coefficient of the solidified body is ≥1.1.

[0018] In one embodiment of the present invention: in step three, after the grouting of the soft pile B pile is completed, it is allowed to stand for 2h-3h to allow the solidified body to initially solidify. During this period, the initial setting state of the solidified body is monitored. After the solidified body has the target plastic strength, the casing is pulled out at a uniform speed, and the pulling-out speed is controlled at 1m / min-2m / min to avoid damage to the solidified body structure due to too fast pulling-out, so as to form a complete B pile body. The compressive strength of the pile body after final setting must reach C10-C15, and the anti-seepage grade must be ≥P6.

[0019] In one embodiment of the present invention: in step 4, within 8h-12h before the initial setting of the B pile solid body, the long screw pile driver is positioned between adjacent B piles, and the cutting device is started to cut the adjacent B pile solid bodies, and the cutting depth reaches the designed pile length, so that the bite amount between the piles is 200mm-300mm, and the split steel cage is hoisted, with the main reinforcement diameter of the steel cage ≥16mm and the stirrup spacing 200mm. The steel cage is precisely positioned by the guide frame to make the thickness of the protective layer of the steel cage uniform and the verticality deviation ≤3‰.

[0020] In one embodiment of the present invention: In step five, for sand layers and permeable strata, high-pressure rotary jet piles with a diameter of 600mm-620mm are used for pre-reinforcement before the construction of B piles, and two rows are constructed at a spacing of 0.8m-0.9m to form a water stop ring. The casing wall thickness is selected to be ≥20mm, and the sinking speed is ≤0.3m / min. For pebble layers, a roller drill bit (torque ≥200kN·m) is used to penetrate the pebble layer, and the casing wall thickness is increased to 25mm-27mm. For moderately weathered rock layers, an impact hammer with an impact force of ≥300kN is used to crush the rock layer, and the casing is followed until it is embedded in the intact rock layer for ≥1.0m. The crushed rock chips can replace part of the loose soil after screening for the preparation of the solidified body.

[0021] In one embodiment of the present invention: in step six, after the concrete of pile A has finally set, the low-strain method is used to detect the integrity of the pile body to ensure that the proportion of Class I piles is ≥90%, and multiple piles are continuously operated in an alternating order of "B pile → A pile → B pile", and steps two to six are repeated until the construction of all the interlocking piles is completed to form a continuous water-stopping and supporting wall.

[0022] Example 1, please refer to the attached Figure 1 , Construction of interlocking piles in strata with alternating silty clay and sand layers: Applied to a deep foundation pit project for a high-rise building. The foundation pit is 18m deep. The site stratum is mainly silty clay, including a 2-3m thick medium sand layer. The groundwater level is buried at a depth of 6m. Interlocking piles are required to form a water-stop curtain and support structure. The specific construction steps are as follows: Step 1: Using a combination of drilling (drill hole spacing of 5m) and geological radar geophysical exploration, the soil layer distribution was determined to be ① plain fill (2m) → ② silty clay (8m) → ③ medium sand layer (2.5m) → ④ strongly weathered rock layer (unpenetrated). The groundwater level was 6m, the saturated uniaxial compressive strength of the rock was 15MPa, the designed pile length was 22m (1.5m embedded in the strongly weathered rock layer), the pile diameter was 1000mm, and the inter-pile bite thickness was 250mm. A loose soil collection system was established. A 20mm mesh vibrating screen is used to screen and remove impurities (bricks, gravel, etc.) from the loose soil used for piling, and the soil is temporarily stored in a closed silo. Cement slurry is prepared by mixing P.O42.5 cement slurry at a water-cement ratio of 0.5, adding 5% bentonite (mass ratio). After stirring evenly, the slurry is matured for 30 minutes. The Bauer BG30 casing drilling rig (maximum torque 300kN·m), grouting pump (working pressure 0-1MPa) and 50Hz vibrator are debugged to ensure normal operation of the equipment.

[0023] Step 2: After the drilling rig is in place, start the forward rotation to sink the drilling and mixing, and sink the φ1000mm casing in a section-by-section downward pressure method. The length of each casing section is 3m. The inclinometer is used for real-time monitoring to ensure that the verticality deviation is ≤2‰. A hydraulic grab is used to take soil, and the soil taking rate matches the casing sinking rate (0.5m / min). The sieved loose soil (particle size ≤20mm) is simultaneously transported to the mixing tank and mixed with cement slurry in a volume ratio of 1:1.2. It is stirred for 3 minutes to form a plastic solidified body (slump 180mm). The grouting pump is started and the solidified body is injected into the casing through the φ100mm high-pressure grouting pipe. The grouting pressure is controlled at 0.4MPa. At the same time, a 50Hz vibrator is used to vibrate in sections (every 3m is a section, and vibration is 1.5min). After stirring to the designed depth, it is lifted up and stirred in the reverse direction to the ground to complete a soft pile, ensuring that the filling coefficient of the solidified body reaches 1.15.

[0024] Step 3: After the grouting of pile B is completed, it is left to stand for 2.5 hours to allow the solidified body to initially solidify (the on-site test shows that the penetration resistance reaches 1.5 MPa). The casing is pulled out at a uniform speed of 1.5 m / min to form a complete pile B. After final setting, the test shows that the compressive strength of pile B is C12 and the anti-seepage grade is P8.

[0025] Step 4: Before the soft piles begin to set, use the drill bit of a long spiral pile driver to cut adjacent soft piles and drill down to the bottom of the hole. Then, lift the drill upwards and use a concrete pump to inject superfluid concrete from the center of the drill rod to the bottom of the hole onto the ground. Then, use a vibrator to vibrate the concrete and insert the steel cage to form an A pile.

[0026] Step 5: For the sand layer in the site, use 600mm diameter high-pressure rotary jet piles for pre-reinforcement before the construction of B piles. Two rows (row spacing 1.2m) are constructed at a spacing of 0.85m, with a cement content of 25% to form a water stop ring. The casing is made of Q345B steel pipe with a wall thickness of 20mm, and the sinking speed is controlled at 0.25m / min to avoid collapse of the sand layer.

[0027] Step 6: 48 hours after the final setting of the A pile concrete, the low-strain method was used for testing. Class I piles accounted for 95%, and continuous construction was carried out in the order of "B pile → A pile → B pile". A total of 120 interlocking piles were completed, forming a continuous water-stopping and supporting wall with a length of 120m.

[0028] Example 2, please refer to the attached Figure 1 , Construction of interlocking piles in pebble layer and medium weathered rock layer: This embodiment is applied to a certain underground integrated pipe gallery project. The foundation pit depth is 15m. The site strata are ① miscellaneous fill (3m) → ② pebble layer (5m, particle size 50-200mm, content 60%) → ③ moderately weathered rock layer (buried at a depth of 8m, saturated uniaxial compressive strength 30MPa). Snap piles are required to penetrate the pebble layer and the rock layer. The specific construction steps are as follows: Step 1: Obtain formation parameters through drilling (coring rate ≥ 80%) and sonic logging geophysical exploration: the characteristic value of the bearing capacity of the pebble layer is 500kPa, the integrity coefficient of the moderately weathered rock layer is 0.7, the designed pile length is 20m (embedded 2m in the moderately weathered rock layer), the pile diameter is 1200mm, the inter-pile bite thickness is 300mm, the loose soil is sieved through a 25mm sieve and temporarily stored, the cement slurry is prepared at a water-cement ratio of 0.55, and 8% fly ash (mass ratio) is added, and the casing drilling rig (equipped with a roller drill bit and an impact hammer), the grouting pump (maximum pressure 1.5MPa) and the 60Hz vibrator are debugged.

[0029] Step 2: After the drilling rig is in place, start the forward rotation and sink the drilling and mixing, sink the φ1200mm casing to the top surface of the pebble layer, replace the roller drill bit (torque 220kN・m) to penetrate the pebble layer, follow the casing section by section, and control the vertical deviation to ≤3‰. During the soil excavation process, mix the sieved loose soil with the crushed pebble fine material (particle size ≤20mm), and stir it with cement slurry at a volume ratio of 1:1.5 to form a solidified body. Inject high-pressure cement slurry while stirring to mix the cement slurry and loose soil evenly. The grouting pressure is 0.5MPa, and a 60Hz vibrator is used to vibrate in sections (every 2m, vibrating for 2min). After stirring to the designed depth, lift it up and stir it in the reverse direction to the ground. The filling coefficient reaches 1.2.

[0030] Step 3: After the grouting of pile B is completed, let it stand for 3 hours. When the penetration resistance of the solidified body reaches 2.0MPa, pull out the pipe at a speed of 1m / min. After final setting, the test shows that the compressive strength of pile B is C15 and the anti-seepage grade is P6.

[0031] Step 4: 8 hours before the initial setting of pile B, use the drill bit of a long spiral pile driver to cut the adjacent soft pile and drill down to the bottom of the hole. Then, lift the drill upwards and use a concrete pump to inject superfluid concrete from the center of the drill rod to the bottom of the hole onto the ground. Then, use a vibrator to vibrate the concrete and insert the steel cage to form a pile A.

[0032] Step 5: For the pebble layer, the casing wall thickness is increased to 26mm, and the sinking speed is 0.2m / min; when encountering moderately weathered rock layers, a 350kN impact hammer is used to crush them, and the casing is followed until it is embedded 1.2m into the intact rock layer. After screening, the crushed rock chips replace 30% of the loose soil for solidification.

[0033] Step 6: A pile inspection: Class I piles account for 92%. 80 piles were constructed in an alternating sequence to form a continuous support structure that meets the water-stopping and soil-retaining requirements of the tunnel construction.

[0034] According to the contents of the above embodiments, it can be concluded that through the resource utilization of pile driving virtual soil and the preparation of cement slurry solidification body, the optimization of the construction process of B pile and A pile, the application of targeted treatment technology for special strata and the precise control of parameters in each link, the traditional super-slow-setting concrete is effectively replaced, the material cost and construction period are reduced, and at the same time, the quality risks of pile formation in complex strata are eliminated, the impermeability and stability of the pile body are improved, and with the help of the coordinated cooperation of various process steps, the good effect of enhancing construction economy and efficiency and controlling construction risks can be achieved.

[0035] Although the present invention is disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent variations, and modifications made to the above embodiments in accordance with the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A construction method for interlocking piles based on a virtual soil-cement slurry solidified body, including a construction method characterized by: The construction method comprises the following steps: Step 1: Use a combination of drilling and geophysical exploration to obtain the target site's stratigraphic parameters and design pile parameters. Establish a system for collecting and pre-processing loose soil, remove impurities, and temporarily store it. Then, prepare cement slurry and debug construction equipment. Step 2: After the drilling rig is in place, start the forward rotation and drill down to mix. While mixing, inject high-pressure cement slurry to mix the cement slurry and loose soil evenly. After mixing to the designed depth, lift it up and mix it in the reverse direction to the ground to complete a soft pile. Step 3: After grouting is completed, let the solidified body stand for initial solidification, and then pull out the casing at a uniform speed to form pile B; Step 4: Before the soft piles begin to set, use the drill bit of a long screw pile driver to cut adjacent soft piles and drill down to the bottom of the hole. Then, lift the drill upwards and use a concrete pump to inject superfluid concrete from the center of the drill pipe to the bottom of the hole and onto the ground. Then, use a vibrator to vibrate the concrete and insert the steel cage to form an A pile. Step 5: Targeted construction treatment for special strata: For sandy and permeable strata, pre-reinforcement is carried out before B pile construction; for gravel strata, casing optimization is carried out; for moderately weathered rock strata, crushing technology is used to form piles; Step 6: Perform quality inspection on pile A and repeat the construction in alternating order to form a continuous interlocking pile wall.

2. The method for constructing interlocking piles based on a solidified body of virtual soil and cement slurry according to claim 1, characterized in that: In the step 1, a method combining drilling and geophysical exploration is used to obtain the stratigraphic parameters of the target site, including soil layer distribution, groundwater level, rock strength and permeability. The pile length, pile diameter and inter-pile bite thickness are designed based on this. A loose soil collection and pretreatment system is established. The loose soil generated by the pile driving construction is sieved through a 20mm-25mm sieve to remove impurities. After removing the impurities, it is temporarily stored. Subsequently, cement slurry is prepared and formulated at a water-cement ratio of 0.4-0.6, wherein 5%-10% of bentonite and fly ash are added. The grouting pump, vibrating equipment and casing drilling rig are simultaneously debugged to ensure that the equipment parameters meet the construction requirements.

3. The construction method of interlocking piles based on the virtual soil-cement slurry solidified body according to claim 1 is characterized in that: In the step 2, after the drilling rig is in place, the casing is pressed down section by section to the designed depth, and the verticality deviation of the casing is ensured to be ≤3‰ by real-time monitoring with an inclinometer. A grab bucket is used to take soil, and the sieved loose soil is simultaneously transported to a mixing tank and mixed with the prepared cement slurry in a volume ratio of 1:1-1:1.

5. The soil is stirred to form a uniform plastic solidified body, and the grouting pump is started. The loose soil-cement slurry solidified body is injected into the casing through a high-pressure grouting pipe. The grouting pressure is controlled at 0.3MPa-0.5MPa. At the same time, a vibrating rod with a frequency of 50Hz-60Hz is used for segmented vibration, and the vibration time of each segment is 1min-2min, so that the filling coefficient of the solidified body is ≥1.

1.

4. The method for constructing interlocking piles based on a solidified body of virtual soil and cement slurry according to claim 1, characterized in that: In the step 3, after the grouting of the soft pile B is completed, it is left to stand for 2h-3h to allow the solidified body to initially solidify. During this period, the initial setting state of the solidified body is monitored. After the solidified body has the target plastic strength, the casing is pulled out at a uniform speed. The pulling-out speed is controlled at 1m / min-2m / min to avoid damage to the solidified body structure due to too fast pulling-out, so as to form a complete B pile body. The compressive strength of the pile body after final setting must reach C10-C15, and the anti-seepage grade must be ≥P6.

5. The method for constructing interlocking piles based on a solidified body of virtual soil and cement slurry according to claim 1, characterized in that: In step 4, within 8-12 hours before the initial setting of the B pile solidification body, the long screw pile driver is positioned between adjacent B piles, and the cutting device is started to cut the adjacent B pile solidification bodies, with the cutting depth reaching the designed pile length, so that the inter-pile bite is 200mm-300mm.

6. The method for constructing interlocking piles based on a solidified body of virtual soil and cement slurry according to claim 1, characterized in that: In the step five, for sand layers and permeable strata, high-pressure rotary jet piles with a diameter of 600mm-620mm are used for pre-reinforcement before the construction of B piles. Two rows are constructed with a spacing of 0.8m-0.9m to form a water stop ring. The casing wall thickness is selected to be ≥20mm, and the sinking speed is ≤0.3m / min. For the pebble layer, a roller drill bit is used to penetrate the pebble layer, and the casing wall thickness is increased to 25mm-27mm. For the moderately weathered rock layer, an impact hammer with an impact force of ≥300kN is used to crush the rock layer, and the casing is followed until it is embedded in the complete rock layer for ≥1.0m. The crushed rock chips can replace part of the loose soil after screening for the preparation of the solidified body.

7. The method for constructing interlocking piles based on a solidified body of virtual soil and cement slurry according to claim 1, characterized in that: In step 6, after the concrete of pile A has finally set, the low-strain method is used to test the integrity of the pile body to ensure that the proportion of Class I piles is ≥ 90%. Continuous operation of multiple piles is carried out in an alternating order of "B pile → A pile → B pile", and steps 2 to 6 are repeated until all the interlocking piles are constructed to form a continuous waterstop and support wall.

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