A drilling-while-drilling pile construction device and method for calcareous sand formations

Abstract

The present invention relates to the technical field of building construction, and in particular to a device and method for constructing while-drilling pipe piles in calcareous sand formations. The drilling rig assembly includes a pipe pile drilling rig and a pile control fixture fixedly installed on a preset pile position; a long spiral drill rod is movably hoisted on the power head of the pipe pile drilling rig, and a reaming drill bit is fixedly installed on the end of the long spiral drill rod, and the long spiral drill rod extends into the inner cavity of the pipe pile while drilling, and the top of the pipe pile while drilling is connected to the power head fixture installed on the power head, and the pipe pile while drilling is clamped or released by the power head fixture; the pile control fixture is sleeved on the outer periphery of the pipe pile while drilling, and is used to clamp or release the pipe pile while drilling; the air pressure regulating assembly includes an air pump and a sealing plug adapted to the inner cavity of the pipe pile while drilling. When the air pressure is adjusted, the pile control fixture clamps the pipe pile while drilling to achieve sealing on the pile side of the pipe pile while drilling, and the sealing plug is arranged on the top of the pipe pile while drilling, and the air pump is sealed and connected to the pile side grouting pipe on the pipe wall of the pipe pile while drilling.

Description

Technical Field

[0001] The present invention relates to the technical field of building construction, and in particular to a drilling-while-drilling pipe pile construction device and method for calcareous sand formations. Background Art

[0002] Calcareous sand is widely distributed between 30° north and south latitude on Earth and is found in many countries around the world. It is an unavoidable type of geotechnical engineering medium. In my country's South China Sea, numerous islands are covered with large amounts of calcareous sand and gravel. These coral reefs are rich in marine resources and possess significant strategic value. The development of coral reefs to serve my country's socio-economic, national defense, military, scientific research, cultural tourism, and other sectors is gradually unfolding. This has led to an increasing scale and number of island and reef construction projects, posing numerous challenges related to calcareous sand. Pile foundations are a common foundation form on coral reefs, and the engineering characteristics of calcareous sand pile foundations are a key research topic in island and reef engineering, holding significant engineering research significance.

[0003] Common types of pipe piles used in calcareous sand formations include precast piles and bored piles. For example, the patent application with publication number CN108086298A, filed by Chongqing University and titled "A Microbial Grouting Pipe Precast Pipe for Reinforcing Calcareous Sand Foundations and Its Construction Method," mentions:

[0004] A construction method for microbial grouting pipe prefabricated piles for reinforcing calcareous sand foundations comprises the following steps:

[0005] 1) Prefabricated piles are manufactured in a factory; wherein a plurality of grouting pipes are arranged vertically in the core of the prefabricated pile; the grouting pipes penetrate the top and side surfaces of the prefabricated pile; the upper ends of the grouting pipes are grouting holes, and the lower ends are discharge holes; the discharge holes of the grouting pipes are sealed with hole plugs;

[0006] 2) Install the precast piles into the calcareous sand foundation by static pressure or hammering according to the design requirements;

[0007] 3) using grouting equipment to pump the reaction liquid into the grouting pipe; the reaction liquid penetrates into the calcareous sand around the precast pile tip;

[0008] 4) injecting a bacterial suspension into the grouting pipe; the bacterial suspension penetrates into the calcareous sand around the prefabricated pile tip; the bacteria hydrolyze urea to produce calcium carbonate, which cements the broken sand layer at the pile tip to form a grouting reinforcement;

[0009] 5) Repeat steps 3) and 4) until the pile foundation bearing capacity and deformation performance meet the design requirements;

[0010] 6) Use compacted concrete to fill the grouting pipe to the top of the pile.

[0011] However, precast pile foundations constructed using the hammering or static pressure methods are difficult to construct in hard strata and are prone to damage to the pile body or even broken piles. The pile ends can generally only penetrate sand layers and strongly weathered rock layers (1 to 3 meters deep) and are difficult to penetrate into medium or slightly weathered rock layers. The pile diameter is generally difficult to exceed 600 mm, and the vertical bearing capacity of a single precast pipe pile generally does not exceed 3500 kN.

[0012] As for bored cast-in-place piles, although their bearing capacity is relatively high (reaching more than 20,000 kN), the geological conditions of the calcareous sand strata are relatively complex, the construction of bored cast-in-place piles is difficult, the quality control of the piles during the construction process is difficult, the construction cost is high, and a large amount of mud will be generated during construction, which can easily cause environmental pollution and hole collapse. At the same time, mud wall protection is required during the construction of bored cast-in-place piles, which blocks the gaps in the calcareous sand strata and leads to insufficient friction resistance on the pile side. In addition, because the particles of calcareous sand are coarse, the edges are large, and there are many pores, the poured cement slurry can easily penetrate into the soil layer around the pile, resulting in reduced pile strength.

[0013] Based on this, the present invention provides a device and method for constructing piles while drilling in calcareous sand formations to overcome the above-mentioned defects. Summary of the Invention

[0014] The first purpose of the present invention is to provide a drilling-while-pile construction device for calcareous sand formations. The drilling-while-pile piles produced by the above-mentioned construction device do not require mud wall protection during construction, and rely on the pipe wall itself to protect the wall, ensuring that the gaps in the calcareous sand formation are not blocked after construction. After grouting the pile side, the slurry can penetrate into the gaps, thereby greatly improving the pile side friction resistance, and are energy-saving, environmentally friendly, and have good pile formation effects.

[0015] The present invention adopts the following technical solution: a drilling and pipe pile construction device for calcareous sand formations,

[0016] It includes pipe piles while drilling, drilling rig components and air pressure regulating components;

[0017] The drilling rig assembly includes a pipe pile drilling rig and a pile control fixture fixedly installed on a preset pile position; a long spiral drill rod is movably hoisted on the power head of the pipe pile drilling rig, a reaming drill bit is fixedly installed on the end of the long spiral drill rod, the long spiral drill rod extends into the inner cavity of the while-drilling pipe pile, and the top of the while-drilling pipe pile is connected to the power head fixture installed on the power head, and the while-drilling pipe pile is clamped or loosened by the power head fixture; the pile control fixture is sleeved on the outer periphery of the while-drilling pipe pile for clamping or loosening the while-drilling pipe pile;

[0018] The air pressure regulating assembly includes an air pump and a sealing plug adapted to the inner cavity of the drilling-while-pipe pile. When air pressure regulation is required, the pile control fixture clamps the drilling-while-pipe pile to achieve sealing of the pile side of the drilling-while-pipe pile, and the sealing plug is arranged on the top of the drilling-while-pipe pile. The air pump is sealed and connected to the pile side grouting pipe on the wall of the drilling-while-pipe pile.

[0019] Furthermore, a waterproof bag for storage is placed in the inner cavity of the drilling-while-pipe pile.

[0020] Furthermore, the waterproof bag is made of flexible material.

[0021] Furthermore, the construction device also includes a cleaning hook, which removes the sealing plug of the drilling-while-pipe pile. The cleaning hook extends into the inner cavity of the drilling-while-pipe pile to clean the bottom of the hole at the end of the drilling-while-pipe pile.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) In the construction device of the present invention, during construction, the long spiral drill rod is extended into the inner cavity of the drilling and pipe pile, the power head clamp on the power head clamps the drilling and pipe pile, and the spiral drilling and the drilling and pipe pile follow-up are carried out simultaneously. The drilling and pipe pile follow-up is basically achieved by its own weight. When it is difficult to sink, the power head can also be used to provide vertical power to assist sinking, complete the drilling and the initial installation of the drilling and pipe pile, and then start the air pressure regulating component to achieve air pressure regulation of the inner cavity of the drilling and pipe pile and the soil around the pile.

[0024] When the bottom of the hole of the while-drilling pipe pile is not filled with ultra-fine concrete, the air pump is started to pump negative pressure into the inner cavity of the while-drilling pipe pile and the soil around the pile, forming a pile-soil gap, draining the moisture in the soil near the pile, consolidating the soil around the pile, and thus improving the physical and mechanical properties of the soil; at the same time, drainage is carried out under negative pressure, which can flush out the debris in the voids of the calcareous sand stratum soil during the drilling process, open the voids of the calcareous sand stratum soil, so that the slurry can penetrate into the soil layer during the later pile side grouting, thereby increasing the pile side friction resistance.

[0025] When the ultra-fine concrete is being filled at the bottom of the pile end of a drilled tubular pile, and before the ultra-fine concrete reaches initial setting, the air pump is activated to pump air into the gap between the inner cavity of the drilled tubular pile and the pile-soil, creating a large positive pressure. This pressure forces some of the ultra-fine concrete into the rock and soil at the pile end. This positive pressure allows the ultra-fine concrete to better fill the voids and cracks at the pile end, increasing the strength of the soil at the pile end, increasing the contact area between the pile end and the rock and soil, and reducing the permeability of the pile end, thereby improving the bearing capacity and durability of the pile end. At the same time, it allows the pile body to be more tightly integrated with the surrounding soil, increasing its stability and reducing its settlement and tilt.

[0026] It can be seen that the drill-while-drilling pipe piles made using the above-mentioned construction device have no mud wall protection during the construction process, and rely on the pipe wall itself to protect the wall, ensuring that the gaps in the calcareous sand formation are not blocked after construction. After grouting the pile side, the slurry can penetrate into the gaps, thereby greatly improving the friction resistance of the pile side, and it is energy-saving, environmentally friendly, and has a good pile-forming effect.

[0027] 2) The waterproof bag can not only store oil and water, but also utilizes the internal space of the drilled pile as a chamber for electrolyte and electrode plates, transforming the pile into a battery with energy storage capabilities. In this way, the pile not only bears structural loads but also stores green energy or excess grid power, releasing it during peak hours to effectively balance the grid load. This has a positive impact on the current situation of land resources being extremely valuable on islands and reefs. Furthermore, the waterproof bag, located underground within the drilled pile, effectively protects the media within the bag. This provides excellent protection for the fresh water, oil, and electrolyte used for charging and discharging stored within the pile during extreme environments such as war, tsunamis, and earthquakes.

[0028] A second object of the present invention is to provide a method for constructing piles while drilling in calcareous sand formations, comprising the following steps:

[0029] S01. Preliminary preparation: According to the results of the preliminary engineering geological drilling, ensure that the drilling piles are embedded in the medium to slightly weathered rock layer for more than 0.5m. Based on this, the pile length of the drilling piles is determined and waterproof bags are made;

[0030] S02. Construction preparation: Place the pile control fixture at the preset pile position to clamp the pile while drilling. Then, move the pile drilling rig into position. Use the pile drilling rig to hoist the long spiral drill rod and reaming drill bit into the inner cavity of the pile while drilling. At the same time, use the power head fixture to clamp the top of the pile while drilling.

[0031] S03. Drilling: The long spiral drill rod and the reaming drill bit drill a hole through the inner cavity of the drilling pipe pile, so that a pile-soil gap is formed between the drilling pipe pile and the soil around the pile, and the drilling pipe pile is simultaneously sunk into the pile hole;

[0032] S04, pumping negative pressure: after the reaming drill bit has penetrated more than 0.5m into the slightly weathered rock layer, the long spiral drill rod and the reaming drill bit are withdrawn from the inner cavity of the while-drilling pipe pile, and the while-drilling pipe pile is clamped with a pile control fixture to achieve sealing of the pile side of the while-drilling pipe pile; at the same time, a sealing plug is placed on the top of the while-drilling pipe pile, and an air pump is sealed and connected to the pile side grouting pipe on the wall of the while-drilling pipe pile. The air pump is started to pump air from the inner cavity of the while-drilling pipe pile and the gap between the pile and the soil, thereby forming a negative pressure. Under the action of the negative pressure, the groundwater in the soil around the pile and the fine stone and soil residues in the pores of the calcareous sand stratum flow into the drill hole at the pile end of the while-drilling pipe pile;

[0033] S05, slag cleaning: Open the sealing plug to restore the inner cavity of the drilling pile to normal atmospheric pressure, then extend the cleaning hook from the inner cavity of the drilling pile into the bottom of the drilled hole at the pile end to clean the groundwater, fine stone slag and fine soil slag at the bottom of the hole. After cleaning, withdraw the cleaning hook;

[0034] S06. Grouting: Ultrafine concrete is poured from the inner cavity of the drilling pipe pile to the bottom of the hole. When the ultrafine concrete liquid level reaches the designed value, grouting is stopped. After grouting is completed, a sealing plug is placed on the top of the drilling pipe pile. At the same time, an air pump is started to pump air into the inner cavity of the drilling pipe pile and the gap between the pile and the soil to form positive pressure. Under the action of the positive pressure, part of the ultrafine concrete enters the rock and soil layer at the pile end. After the positive pressure is completed, fine stone concrete is continuously poured through the inner cavity of the drilling pipe pile. The fine stone concrete slowly sinks under the action of gravity and combines with the ultrafine concrete to form a concrete mixture.

[0035] S07. Pile driving: After the concrete mixture is naturally blended, the pile control clamp is released and the drilled pipe pile is slowly driven in. The bottom of the drilled pipe pile and the rock layer under the calcareous sand stratum are formed into an integral structure with the help of ultra-fine concrete and fine stone concrete.

[0036] S08, Pile side grouting: Pile side grouting is carried out through the pile side grouting pipe on the wall of the drilled pile, and concrete is injected into the gap between the pile and the soil;

[0037] S09, making the capping platform: after the concrete slurry seepage is relatively still and solidified, put the waterproof bag prefabricated in step S01 into the inner cavity of the drilling pile, make the capping platform, and reserve a through hole.

[0038] Furthermore, in step S09, a sealing ring is laid between the bottom of the support platform and the ground, and a through hole is reserved in the sealing ring. The through hole on the sealing ring is arranged opposite to the through hole on the support platform.

[0039] Furthermore, a hook is provided in the support platform, a rope is provided on the top of the waterproof bag, and the waterproof bag is fixed to the hook of the support platform through the rope.

[0040] Furthermore, the sealing plug in step S04 is made of rubber.

[0041] Furthermore, the reaming drill bit in step S03 is a down-the-hole hammer reaming drill bit;

[0042] When the expansion wing plate of the down-the-hole hammer reaming drill bit is in a retracted state, it can freely enter and exit the inner cavity of the drilling pile; after the expansion wing plate of the down-the-hole hammer reaming drill bit is opened, the diameter of the drilled hole is 15mm to 25mm larger than the outer diameter of the drilling pile.

[0043] Furthermore, a plurality of grouting outlets are reserved on the drilling-while-pipe pile, and the plurality of grouting outlets are all connected with the pile side grouting pipe on the side wall of the drilling-while-pipe pile. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 Schematic diagram of drilling construction for construction equipment;

[0046] Figure 2 This is a construction diagram showing the construction device drilling through the lower rock layer;

[0047] Figure 3 Schematic diagram of the construction device for sealing the pile side and the inner cavity of the pile while drilling;

[0048] Figure 4 This is a construction diagram of the medium-pressure air pump of the construction device pumping negative pressure into the soil around the pile;

[0049] Figure 5 This is a construction diagram of the cleaning hook in the construction device cleaning the soil, debris and gravel at the bottom of the pile hole;

[0050] Figure 6 This is a schematic diagram of the construction device injecting ultra-fine concrete into the inner cavity of the drilling pile;

[0051] Figure 7 This is a schematic diagram of the construction device injecting fine stone concrete into the inner cavity of the drilling and pipe pile;

[0052] Figure 8 This is a schematic diagram of the construction of pile sinking while drilling in calcareous sand formations;

[0053] Figure 9 This is a schematic diagram of the construction device injecting concrete into the side of the drilling and pipe pile;

[0054] Figure 10 This is a schematic diagram of slurry seepage after the construction device injects concrete into the pile side;

[0055] Figure 11 Schematic diagram of the construction of capping platform for drilling and pipe pile in calcareous sand formation;

[0056] Figure 12 This is a partial enlarged schematic diagram of the capping of the pile while drilling in the calcareous sand formation at point A;

[0057] Figure 13 This is a top view structural diagram of the pile cap while drilling in calcareous sand formations;

[0058] Figure 14 This is a schematic diagram of using waterproof bags in the inner cavity of piles for oil and water storage while drilling in calcareous sand formations;

[0059] Figure 15 Schematic diagram of using a waterproof bag as a chemical battery in the inner cavity of a pipe pile while drilling in a calcareous sand formation.

[0060] Among them: 1-pipe pile drilling rig, 2-pipe pile while drilling, 3-air pressure regulating assembly, 4-power head, 5-long spiral drill rod, 6-reaming drill bit, 7-power head clamp, 8-pile control clamp, 9-calcareous sand formation, 10-sealing plug, 11-air pump, 12-pile side grouting pipe, 13-pile clamp base, 14-slurry outlet, 15-waterproof bag, 16-cleaning hook, 17-sealing ring, 18-cap, 19-through hole, 20-rock layer, 21-pile-soil gap, 22-ultra-fine concrete, 23-fine stone concrete, 24-concrete mixture, 25-concrete delivery pump, 26-concrete container, 27-chemical battery electrode sheet. DETAILED DESCRIPTION

[0061] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0062] The following is combined with Figure 1 To the attached Figure 15 And specific embodiments, the present invention is discussed in detail:

[0063] like Figure 1-15 As shown, the present invention provides a drilling-while-drilling pipe pile construction device for calcareous sand formations, which includes a drilling-while-drilling pipe pile 2, a drilling rig assembly, and an air pressure regulating assembly 3.

[0064] The drilling rig assembly includes a pipe pile drilling rig 1 and a pile control fixture 8 fixedly installed on a preset pile position.

[0065] A long auger rod 5 is movably mounted on the power head 4 of the pipe pile drilling rig 1. A reamer drill bit 6 is fixedly mounted on the end of the long auger rod 5. The long auger rod 5 extends into the inner cavity of the pipe pile 2 while being drilled. The top of the pipe pile 2 while being drilled is connected to a power head fixture 7 mounted on the power head 4. The power head fixture 7 is used to clamp or release the pipe pile 2 while being drilled. Specifically, one end of the power head fixture 7 is movably connected to the power head 4, and the other end is controlled by a cylinder to tighten and loosen the pipe pile 2 while being drilled.

[0066] The pile control fixture 8 is mounted on the periphery of the drilled pile 2 and is used to clamp or release the drilled pile 2, controlling its sinking speed. When the pile control fixture 8 clamps the drilled pile 2, it seals the side of the drilled pile 2. Specifically, the pile control fixture 8 includes a pile clamp base 13 and a retractable sealing chuck mounted on the pile clamp base 13. When the pile control fixture 8 is required to clamp the drilled pile 2, the sealing chuck extends to clamp the drilled pile 2. The pile clamp base 13 is made of metal and has a ring-shaped structure. It has a large contact area with the ground and can withstand the significant vertical deadweight pressure of the drilled pile 2. Furthermore, the pile control fixture 8 distributes the vertical clamping force to the ground through the pile clamp base 13, maintaining the drilled pile 2 vertical during construction and preventing the pile from shifting or toppling due to the release of the top power head fixture 7.

[0067] The air pressure regulating assembly 3 includes an air pump 11 and a sealing plug 10 adapted to the inner cavity of the drilling-while-pipe pile 2. When the drilling is completed and air pressure regulation is required, the pile control fixture 8 clamps the drilling-while-pipe pile 2 to achieve sealing of the pile side of the drilling-while-pipe pile 2, and the sealing plug 10 is arranged on the top of the drilling-while-pipe pile 2. The air pump 11 is sealedly connected to the pile side grouting pipe 12 on the wall of the drilling-while-pipe pile 2. The air pump 11 can be used to regulate the air pressure of the inner cavity of the drilling-while-pipe pile 2 and the soil around the pile.

[0068] The construction device in the present invention, during construction, the long spiral drill rod 5 is extended into the inner cavity of the drilling and following-up pipe pile 2, the power head clamp 7 on the power head 4 clamps the drilling and following-up pipe pile 2, the spiral drilling and the following-up of the drilling and following-up pipe pile 2 are carried out simultaneously, and the following-up of the drilling and following-up pipe pile 2 is basically achieved by its own weight. When it is difficult to sink, the power head 4 can also be used to provide vertical power to assist sinking, complete the drilling and the initial installation of the drilling and following-up pipe pile 2, and then start the air pressure regulating component 3 to achieve air pressure regulation of the inner cavity of the drilling and following-up pipe pile 2 and the soil around the pile.

[0069] When the bottom of the hole of the while-drilling pipe pile 2 is not filled with ultra-fine concrete 22, the air pump 11 is started to pump negative pressure into the inner cavity of the while-drilling pipe pile 2 and the soil around the pile, and form a pile-soil gap 21, discharge the moisture in the soil near the pile, consolidate the soil around the pile, and thus improve the physical and mechanical properties of the soil; at the same time, drainage is carried out under negative pressure, which can flush out the debris in the voids of the calcareous sand layer 9 during the drilling process, open the voids of the calcareous sand layer 9, so that the slurry can penetrate into the soil layer during the later pile side grouting, thereby increasing the pile side friction resistance.

[0070] When the ultrafine concrete 22 is being filled at the bottom of the hole at the end of the drilled tubular pile 2, and before the ultrafine concrete reaches initial setting, the air pump 11 is activated to pump air into the gap 21 between the inner cavity of the drilled tubular pile 2 and the pile-soil, thereby creating a large positive pressure. This pressure causes some of the ultrafine concrete 22 to enter the rock and soil layer at the pile end. Under the action of this positive pressure, the ultrafine concrete can better fill the voids and cracks at the pile end, increasing the strength of the soil at the pile end, increasing the contact area between the pile end and the rock and soil layer, and reducing the permeability of the soil at the pile end, thereby improving the bearing capacity and durability of the pile end. At the same time, the pile body can be more tightly integrated with the surrounding soil, increasing the stability of the pile body and reducing the settlement and tilt of the pile body.

[0071] Specifically, a waterproof bag 15 for storage is placed in the inner cavity of the drilling and tubular pile 2. In this embodiment, the waterproof bag 15 is made of flexible material and is made according to the pile length and pile diameter of the drilling and tubular pile 2. The length of the waterproof bag 15 is slightly larger than the pile length of the drilling and tubular pile 2, and the width is slightly smaller than the inner diameter of the inner cavity of the drilling and tubular pile 2. This can ensure that the waterproof bag 15 entering the inner cavity of the drilling and tubular pile 2 can contact the concrete at the pile end, making full use of the inner cavity space of the drilling and tubular pile 2. The comprehensive utilization of the super-large inner cavity space is the key to reducing the overall construction cost.

[0072] This waterproof bag 15 can not only store oil and water, but also utilize the inner cavity of the drilling pile 2 as a chamber for electrolyte and electrode plates, thereby transforming the drilling pile 2 into a battery with energy storage capabilities. In this case, the drilling pile 2 can not only bear structural loads but also store green energy or excess grid power, releasing it during peak hours to effectively balance the grid load. This has a positive impact on the current situation of land resources being extremely valuable on islands and reefs. Furthermore, the waterproof bag 15, located underground within the inner cavity of the drilling pile 2, effectively protects the media within the waterproof bag 15. This provides excellent protection for the fresh water, oil, and electrolyte used for charging and discharging stored within the drilling pile 2 during extreme environments such as war, tsunamis, and earthquakes.

[0073] In addition, the waterproof bag 15 is made of flexible material, which can better fit the inner shape of the drilling and pipe pile 2, make full use of the space, and ensure good contact with the concrete at the pile end; and the flexible material is relatively easier to install into the inner cavity of the drilling and pipe pile 2, and the operation is convenient; it can also have a certain shock-absorbing and buffering effect on the medium stored inside, thereby enhancing the protection performance in extreme environments.

[0074] Specifically, the construction device further includes a cleaning hook 16. After removing the sealing plug 10 of the drilling-while-drilling tubular pile 2, the cleaning hook 16 is inserted into the inner cavity of the drilling-while-drilling tubular pile 2 to clean the bottom of the hole at the end of the drilling-while-drilling tubular pile 2, removing gravel and soil debris from the bottom of the borehole. It should be noted that the present invention does not limit the specific structure of the cleaning hook 16. Those skilled in the art can design it according to actual conditions. Alternatively, a cleaning hook 16 in the prior art can be directly used. As long as it can achieve the above-mentioned functions, it falls within the scope of protection of the present invention.

[0075] The present invention also provides a method for constructing piles while drilling in calcareous sand formations, such as Figure 1 - to 15, which includes the following steps:

[0076] S01. Preliminary Preparation: According to the results of the preliminary engineering geological drilling, ensure that the drilled pile 2 is embedded in the medium to slightly weathered rock layer for more than 0.5m. Based on this, the pile length of the drilled pile 2 is determined, and a waterproof bag 15 is manufactured according to the pile length and pile diameter of the drilled pile 2. To ensure that the grouting outlet 14 of the drilled pile 2 is not blocked during the pile side grouting, the grouting outlet 14 is set approximately 2m to 3m away from the pile end of the drilled pile 2. At the same time, multiple grouting outlets 14 are reserved on the drilled pile 2. Multiple grouting outlets 14 are connected to the pile side grouting pipe 12, reducing the risk of grouting failure caused by simultaneous blockage of the grouting outlets 14. At the same time, grouting multiple grouting outlets 14 simultaneously ensures that the pile side grouting can be completed quickly. It should also be noted that in actual construction, according to the drilling results, the drilling follow-up pipe pile 2 is generally composed of multiple pipe piles, and adjacent pipe piles are connected together by welding. Correspondingly, the slurry outlet 14 is set on the side wall of the lowest layer of pipe piles, and the slurry outlet 14 is about 2m to 3m away from the pile end of the pipe pile.

[0077] S02, construction preparation: the pile control device clamp 8 is placed at the preset pile position, at this time, the pile control device clamp 8 is in a loose state; then the pipe pile drilling rig 1 is put in place, and the power head 4 of the pipe pile drilling rig 1 movably hoists the long spiral drill rod 5 and the reaming drill bit 6 into the inner cavity of the while-drilling pipe pile 2. At the same time, the power head clamp 7 is used to clamp the top of the while-drilling pipe pile 2, so that the reaming drill bit 6 is set at a distance of about 1m to 3m from the pile end of the while-drilling pipe pile 2, preferably 3m, to ensure that the reaming drill bit 6 does not bump into and damage the while-drilling pipe pile 2 during operation, and at the same time, ensure that the residual soil generated by drilling smoothly enters the inner cavity of the pipe pile, and is then brought out to the ground by the blades of the long spiral drill rod in the inner cavity.

[0078] S03. Drilling: The power head 4 is activated, and the long spiral drill rod 5 and reaming drill bit 6 drill through the inner cavity of the while-drilling tubular pile 2. Rotating, they create a borehole larger than the outer diameter of the while-drilling tubular pile 2, creating a pile-soil gap 21 between the while-drilling tubular pile and the surrounding soil. The while-drilling tubular pile 2 is then simultaneously sunk into the pile hole. The generated soil and gravel are discharged from the top of the while-drilling tubular pile 2 through the inner cavity of the while-drilling tubular pile 2 under the action of the long spiral drill rod 5. Specifically, the reaming drill bit 6 is a down-the-hole hammer reaming drill bit. Down-the-hole hammers have strong rock-breaking capabilities, improving drilling efficiency and adapting to various hardness and geological conditions, offering wide adaptability. When the reaming blades of the down-the-hole hammer reaming drill bit are retracted, they can freely enter and exit the inner cavity of the while-drilling tubular pile 2. When the reaming blades of the down-the-hole hammer reaming drill bit are extended, the diameter of the drilled hole is 15 mm to 25 mm larger than the outer diameter of the while-drilling tubular pile 2. In this embodiment, the diameter of the drill hole is about 20 mm larger than the outer diameter of the drilling-while-drilling pipe pile 2, which ensures that the drilling-while-drilling pipe pile 2 and the reaming drill bit 6 can sink smoothly, and ensures that an appropriate pile-soil gap 21 is formed between the drilling-while-drilling pipe pile 2 and the soil around the pile, which is beneficial to subsequent construction and the stability of the pipe pile, and can reduce the resistance during the sinking process of the pipe pile to a certain extent, making the pile sinking process smoother. In addition, it also helps to improve the bonding effect between the pipe pile and the soil, and improve the overall construction quality.

[0079] S04, pumping negative pressure: after the reaming drill bit has drilled into the medium to slightly weathered rock layer for more than 0.5m, the power head 4 rotates in the opposite direction and contracts the expansion wing plate of the reaming drill bit 6. At this time, the diameter of the drill bit is slightly smaller than the inner diameter of the inner cavity of the while drilling pipe pile 2, and then the long spiral drill rod 5 and the reaming drill bit 6 are evacuated from the inner cavity of the while drilling pipe pile 2, and the while drilling pipe pile 2 is clamped with the pile control fixture 8 to achieve the sealing of the pile side of the while drilling pipe pile 2; at the same time, the sealing plug 10 is set on the top of the while drilling pipe pile 2, the air pump 11 is sealed and connected to the pile side grouting pipe 12 on the wall of the while drilling pipe pile 2, and the air pump 11 is started to pump the air into the inner cavity of the while drilling pipe pile 2 and the pile-soil gap 2 1, thereby forming a negative pressure. Under the action of negative pressure, the groundwater in the soil around the pile and the fine stone debris and fine soil debris in the pores of the calcareous sand layer flow into the drilled hole at the end of the drilled pipe pile 2. Based on this, the moisture in the soil near the pile is discharged, and the soil around the pile is consolidated, thereby improving the physical and mechanical properties of the soil. At the same time, drainage under negative pressure can flush out the debris in the pores of the calcareous sand layer 9 during the drilling process, open the pores of the calcareous sand layer 9, and facilitate the subsequent injection of cement slurry into the pile-soil gap 21 through the pile side grouting pipe 12. The cement slurry can penetrate into the soil around the pile as much as possible, thereby improving the pile side friction resistance. Specifically, the sealing plug 10 is made of rubber material, which has good elasticity and can fit tightly to the top of the drilled pipe pile 2, ensuring a good sealing effect, effectively preventing air leakage, and maintaining a negative pressure state.

[0080] S05, Debris Removal: After starting the compressed air pump 11 for a period of time, and after the groundwater in the soil surrounding the pile and the fine stone and soil debris in the pores of the calcareous sand stratum 9 have basically flowed into the borehole, the sealing plug 10 is opened to restore the inner cavity of the drilling-mounted pipe pile 2 to normal atmospheric pressure. Then, the cleaning hook 16 is extended from the inner cavity of the drilling-mounted pipe pile 2 into the bottom of the borehole at the pile end to remove the groundwater, fine stone and soil debris at the bottom of the hole. At this time, the distance between the pile end of the drilling-mounted pipe pile 2 and the bottom of the borehole is approximately 3m. The residual soil and other debris within this 3m range are cleaned in the above manner. After cleaning is completed, the cleaning hook 16 is withdrawn. In this embodiment, the cleaning hook 16 is equipped with a long spiral rotary bucket.

[0081] S06. Grouting: Ultrafine concrete 22 is poured from the inner cavity of the drilling-mounted tubular pile 2 to the bottom of the hole. Grouting is stopped when the liquid level of the ultrafine concrete 20 reaches the designed value. The ultrafine concrete liquid level is set based on engineering experience and is generally 3 to 5 meters. After grouting is completed, a sealing plug 10 is immediately placed on the top of the drilling-mounted tubular pile 2. Simultaneously, the air pump 11 is started to pump air into the inner cavity of the drilling-mounted tubular pile 2 and the pile-soil gap 21, creating a large positive pressure. Under the action of the positive pressure, some ultrafine concrete 22 enters the rock and soil layer at the pile end. Under the action of the positive pressure, the ultrafine concrete 22 can better fill the voids and cracks at the pile end, increase the strength of the pile end soil, increase the contact area between the pile end and the rock and soil layer, and reduce the permeability of the pile end soil, thereby improving the bearing capacity and durability of the pile end. At the same time, the pile body is more tightly integrated with the surrounding soil, increasing the stability of the pile body and reducing the settlement and tilt of the pile body.

[0082] After the positive pressure is completed, fine stone concrete 23 is continuously poured into the inner cavity of the pile 2 while drilling. The fine stone concrete 23 slowly sinks under the action of gravity and combines with the ultra-fine concrete 22 to form a concrete mixture 24. The combination of ultra-fine concrete 22 and fine stone concrete 23 increases the bearing capacity and stability of the pile; it also improves the durability of the pile and reduces corrosion and damage to the pile. Specifically, the air pump 11 is activated to positively pressure the pile to a preset positive pressure value, and the preset positive pressure value is maintained for approximately 30 minutes. The positive pressure is then completed. The preset positive pressure value can be designed by those skilled in the art based on engineering experience.

[0083] S07, Pile Driving: After the concrete mixture 24 naturally blends, the pile control fixture 8 is released and the drilled pile 2 is slowly driven in. The ultra-fine concrete 22 and fine stone concrete 23 form a single structure between the pile base and the rock layer beneath the calcareous sand stratum 9. This significantly increases the pile end bearing capacity, reduces production costs, and improves pile quality. Specifically, after pouring the fine stone concrete 23, the concrete mixture 24 blends naturally for 10-20 minutes before the pile control fixture 8 is released.

[0084] S08, pile side grouting: After the drilled pipe pile 2 is pressed into the hole bottom, pile side grouting is performed through the pile side grouting pipe 12 on the wall of the drilled pipe pile 2, and concrete is injected into the pile-soil gap 21. The concrete gradually enters the soil pores of the calcareous sand stratum 9. Since the drainage operation has been performed under the negative pressure state, the pores in the calcareous sand stratum 9 that were originally filled are now opened, so that the cement slurry can penetrate as much as possible into the soil around the pile, thereby increasing the pile side friction resistance. Specifically, the concrete in the concrete container 26 can be pumped into the pile-soil gap 21 by a concrete pump 25. That is, the concrete container 26 is sealed with the pile side grouting pipe 12 preset in the drilled pipe pile 2 by the concrete pump 25. Under the action of the concrete pump 25, concrete is injected into the pile-soil gap 21.

[0085] S09. Fabricate and cap the foundation: After the concrete slurry seepage has become relatively still and solidified, place the waterproof bag 15 prefabricated in step S01 into the inner cavity of the drilled pile 2, fabricate and cap the foundation 18, and reserve a through-hole 19 through which the waterproof bag 15 can enter the inner cavity of the drilled pile 2. The through-hole 19 is sized to accommodate the entry and exit of the waterproof bag 15. This not only facilitates subsequent maintenance and replacement of the waterproof bag 15, but also allows for the exchange of media within the waterproof bag 15 via an external water pipe passing through this through-hole 19. Furthermore, for later use as a chemical battery, this through-hole 19 can also accommodate the entry and exit of chemical battery electrodes 27. In this embodiment, the size of the through-hole 19 is generally approximately 20 to 30 cm, which does not affect the strength of the foundation 18.

[0086] Specifically, in step S09, a sealing ring 17 is laid between the bottom of the base 18 and the ground. The sealing ring 17 has a through hole, which is arranged opposite to the through hole in the base 18. The sealing ring 17 prevents ground water from entering the inner cavity of the drilling-while-drilling pile 2. Specifically, a hook is provided within the base 18, and a rope is provided at the top of the waterproof bag 15. The waterproof bag 15 is fixed to the hook on the base 18 via the rope, achieving a detachable connection of the waterproof bag 15 and facilitating replacement of the waterproof bag 15.

[0087] The general construction process of the drilling-while-drilling pile for calcareous sand formations in the present invention is as follows:

[0088] The long spiral drill rod 5 equipped with the reaming drill bit 6 is used for spiral drilling. When the calcareous sand formation 9 is passed through, the pile control fixture 8 clamps the drill pipe pile 2, and the long spiral drill rod 5 fixed with the reaming drill bit 6 is reversed and withdrawn, taking away soil debris and gravel. During the drilling process, the drill bit is always ensured to be about 3m ahead of the end of the drill pipe pile 2. After the hole is drilled to the designed depth, the reaming drill bit 6 and the long spiral drill rod 5 are pulled out. Subsequently, the top of the drill pipe pile 2 is plugged with a sealing plug 10. At the same time, the pile control fixture 8 clamps the drill pipe pile 2, closing the pile-soil gap 21 formed between the outer wall of the drill pipe pile 2 and the soil around the pile. The air pump 11 is started to extract the air in the inner cavity of the drill pipe pile 2 and the pile-soil gap 21, thereby forming a negative pressure. Under the action of the negative pressure, the soil layer around the pile is filled with air. The groundwater, fine stone debris and fine soil debris flow into the bottom of the hole under the drive of negative pressure, thereby discharging the moisture in the soil near the pile and consolidating the soil around the pile, thereby improving the physical and mechanical properties of the soil. At the same time, drainage is carried out under negative pressure, which can flush out the debris in the voids of the calcareous sand formation soil during the drilling process, open the voids of the calcareous sand formation soil, and facilitate the subsequent injection of cement slurry into the pile-soil gap 21 through the pile side grouting pipe 12. The cement slurry can penetrate into the soil around the pile as much as possible, thereby improving the pile side friction resistance.

[0089] Then, after starting the compressed air pump 11 for a period of time, when most of the moisture in the soil near the pile is discharged, open the sealing plug 10, extend the cleaning hook 16 into the bottom of the hole through the inner cavity of the drilling pipe pile 2, use the cleaning hook 16 to clean the residual soil and groundwater at the bottom of the hole, and then pull out the cleaning hook 16.

[0090] Next, ultrafine concrete 20 made of ultrafine cement is poured from the inner cavity of the while drilling pipe pile 2 to the bottom of the hole. After the pouring is completed, the top of the while drilling pipe pile 2 is plugged with a sealing plug 10, and the air pump 11 is started to pump air into the inner cavity of the while drilling pipe pile and the pile-soil gap 21 to form a large positive pressure. Part of the ultrafine concrete 20 enters the rock and soil layer at the pile end under the action of the large positive pressure. After the positive pressure is completed, fine stone concrete 23 is continued to be poured through the inner cavity of the while drilling pipe pile 2, so that the fine stone concrete 23 slowly sinks under the action of gravity and combines with the ultrafine concrete 22 to form a concrete mixture 24. Therefore, the pile end of the while drilling pipe pile and the rock layer 20 under the calcareous sand stratum 9 form a whole with the help of ultrafine concrete and fine stone concrete, which greatly improves the bearing capacity of the pile end, reduces production costs, and improves the quality of piles.

[0091] During the construction of the drilling and pipe pile, there is no mud wall protection. The pipe wall itself protects the wall, ensuring that the gaps in the calcareous sand formation are not blocked after construction. After grouting the pile side, the slurry can penetrate into the gaps, thereby greatly improving the friction resistance of the pile side. It is energy-saving and environmentally friendly, and has a good pile-forming effect.

[0092] At the same time, the construction method of the present invention can determine different construction plans by setting the length of the drilled pile 2 and the size of the waterproof bag 15 according to the drilling results of calcareous sand formations at different depths. The construction method is clear, the plan is simple and easy to understand, the construction difficulty is low, the pile formation effect is good, the bearing capacity is high, and the cost is low. It fully utilizes the geological resources of calcareous sand, protects the environment, and is energy-saving and environmentally friendly. It can effectively solve the problems of pile formation on calcareous sand foundations and meet various civil and military applications.

[0093] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in this field after reading this specification are all within the scope of protection of the present invention.

Claims

1. A method for constructing piles while drilling in calcareous sand formations, characterized by: It includes the following steps: S01. Preliminary preparation: According to the results of the preliminary engineering geological drilling, ensure that the drilled piles are embedded in the medium to slightly weathered rock layer for more than 0.5m. Based on this, the pile length of the drilled piles is determined, and waterproof bags are made for storage. S02. Construction preparation: Place the pile control fixture at the preset pile position to clamp the pile while drilling. Then, move the pile drilling rig into position. Use the pile drilling rig to hoist the long spiral drill rod and reaming drill bit into the inner cavity of the pile while drilling. At the same time, use the power head fixture to clamp the top of the pile while drilling. S03. Drilling: The long spiral drill rod and the reaming drill bit drill a hole through the inner cavity of the drilling pipe pile, so that a pile-soil gap is formed between the drilling pipe pile and the soil around the pile, and the drilling pipe pile is simultaneously sunk into the pile hole; S04, pumping negative pressure: after the reaming drill bit has penetrated more than 0.5m into the slightly weathered rock layer, the long spiral drill rod and the reaming drill bit are withdrawn from the inner cavity of the while-drilling pipe pile, and the while-drilling pipe pile is clamped with a pile control fixture to achieve sealing of the pile side of the while-drilling pipe pile; at the same time, a sealing plug is placed on the top of the while-drilling pipe pile, and an air pump is sealed and connected to the pile side grouting pipe on the wall of the while-drilling pipe pile. The air pump is started to pump air from the inner cavity of the while-drilling pipe pile and the gap between the pile and the soil, thereby forming a negative pressure. Under the action of the negative pressure, the groundwater in the soil around the pile and the fine stone and soil residues in the pores of the calcareous sand stratum flow into the drill hole at the pile end of the while-drilling pipe pile; S05, slag cleaning: Open the sealing plug to restore the inner cavity of the drilling pile to normal atmospheric pressure, then extend the cleaning hook from the inner cavity of the drilling pile into the bottom of the drilled hole at the pile end to clean the groundwater, fine stone slag and fine soil slag at the bottom of the hole. After cleaning, withdraw the cleaning hook; S06. Grouting: Ultrafine concrete is poured from the inner cavity of the drilling pipe pile to the bottom of the hole. When the ultrafine concrete liquid level reaches the designed value, grouting is stopped. After grouting is completed, a sealing plug is placed on the top of the drilling pipe pile. At the same time, an air pump is started to pump air into the inner cavity of the drilling pipe pile and the gap between the pile and the soil to form positive pressure. Under the action of the positive pressure, part of the ultrafine concrete enters the rock and soil layer at the pile end. After the positive pressure is completed, fine stone concrete is continuously poured through the inner cavity of the drilling pipe pile. The fine stone concrete slowly sinks under the action of gravity and combines with the ultrafine concrete to form a concrete mixture. S07. Pile driving: After the concrete mixture is naturally blended, the pile control clamp is released and the drilled pipe pile is slowly driven in. The bottom of the drilled pipe pile and the rock layer under the calcareous sand stratum are formed into an integral structure with the help of ultra-fine concrete and fine stone concrete. S08, Pile side grouting: Pile side grouting is carried out through the pile side grouting pipe on the wall of the drilled pile, and concrete is injected into the gap between the pile and the soil; S09, making the capping platform: after the concrete slurry seepage is relatively still and solidified, put the waterproof bag prefabricated in step S01 into the inner cavity of the drilling pile, make the capping platform, and reserve a through hole.

2. The method for constructing piles while drilling in calcareous sand formations according to claim 1, characterized in that: In step S09, a sealing ring is laid between the bottom of the support platform and the ground, and a through hole is reserved in the sealing ring. The through hole on the sealing ring is arranged opposite to the through hole on the support platform.

3. The method for constructing piles while drilling in calcareous sand formations according to claim 1, characterized in that: A hook is provided in the supporting platform, a rope is provided on the top of the waterproof bag, and the waterproof bag is fixedly installed on the hook of the supporting platform through the rope.

4. The method for constructing piles while drilling in calcareous sand formations according to claim 1, characterized in that: The sealing plug in step S04 is made of rubber.

5. The method for constructing piles while drilling in calcareous sand formations according to claim 1, characterized in that: The reaming drill bit in step S03 is a down-the-hole hammer reaming drill bit; When the expansion wing plate of the down-the-hole hammer reaming drill bit is in a retracted state, it can freely enter and exit the inner cavity of the drilling pile; after the expansion wing plate of the down-the-hole hammer reaming drill bit is opened, the diameter of the drilled hole is 15mm to 25mm larger than the outer diameter of the drilling pile.

6. The method for constructing piles while drilling in calcareous sand formations according to claim 1, characterized in that: A plurality of grouting outlets are reserved on the drilling-while-pipe pile, and the plurality of grouting outlets are all communicated with the pile side grouting pipes on the side wall of the drilling-while-pipe pile.

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