Construction method of carrier pile

Abstract

The invention provides a construction method of a carrier pile, which can ensure the forming efficiency and the construction quality of a carrier in a soil layer with rich underground water content, and comprises the following steps: 1) sealing a prefabricated hollow pipe body; 2) sinking the prefabricated hollow pipe body; (3) a rammer is placed, the position is marked, and cement sand is mixed and extruded to open a sealing bottom; (4) filling and tamping are conducted, and the tamping position is controlled not to exceed the bottom end of the prefabricated hollow pipe body; (5) the tamping position is controlled to descend gradually and is flush with the bottom end of the prefabricated hollow pipe body; (6) the tamping position is controlled to continue to descend and exceed the bottom end of the prefabricated hollow pipe body; (7) after the three-strike penetration of the rammer is measured, the ramming position is controlled to rise gradually and be flush with the bottom end of the prefabricated hollow pipe body, and (8) material filling bottom sealing or filler tamping bottom sealing is carried out. The construction method further comprises another construction method for controlling the ramming position not to exceed the bottom end of the prefabricated hollow pipe body all the time and controlling the compactness through the filler amount.

Description

Technical Field

[0001] The invention relates to pile foundation construction in the field of civil engineering, and in particular to a construction method of a carrier pile. Background Art

[0002] With the rapid development of infrastructure in my country, the requirements for pile foundations of buildings have also changed significantly, mainly manifested in the increasingly higher requirements for the bearing capacity of the foundation and the increasingly broad requirements for applicability to various complex geological conditions.

[0003] Patent document No. 98101041.5 discloses a construction technology for concrete piles. The characteristics of this technology are that it uses construction waste, concrete fragments, dry hard concrete, etc. as filling materials, and performs filling, tamping, and compaction operations at the bottom of the pile to form an artificial bearing layer to transfer the upper load, thereby improving the bearing capacity of the pile. Subsequently, patent document No. 201610090411.3 discloses a construction method for carrier piles. This technology significantly improves the bearing capacity of the pile end carrier by changing the filler from the original construction waste to a cement sand mixture, and significantly changes the tamping method, and the construction efficiency is also significantly improved. The inventions and innovations of the above two patented technologies have been widely used in the field of construction engineering and have created relatively good social and economic benefits.

[0004] my country's coastal areas are areas where developed cities are concentrated, and there are a large number of construction projects. Most of the geological conditions in coastal areas have the same characteristics, that is, the groundwater content is relatively rich and the soil is relatively soft. This characteristic causes many difficulties for foundation treatment, and the same is true for carrier piles. In recent years' engineering practice and application, it has been found that carrier piles require continuous filling and compaction operations during construction. When the pile end carrier is below the groundwater level, the following three problems are often encountered in engineering applications: First, it is very easy for water to enter the casing during construction, and once water is intruded, filling and compaction operations cannot be performed, resulting in waste piles; second, due to continuous filling and compaction, the soil at the pile end is liquefied due to excessive disturbance, resulting in excessive filling and long construction time, which is also easy to cause waste piles and affect the quality of adjacent piles; third, the three-hit penetration test always fails to meet the standard. Even if it barely meets the standard, it will be found in the later test that the bearing capacity of the pile does not meet the design requirements.

[0005] Now, people have realized that the above-mentioned problems of carrier piles and similar structural piles do limit and affect the promotion and application of technology. Therefore, further research and more comprehensive improvement and development are needed to ensure project quality, improve efficiency and save costs. Summary of the invention

[0006] The present invention is proposed to solve the above-mentioned problems, and its purpose is to provide a construction method of carrier piles. According to the geological characteristics of coastal areas and the technical characteristics of carrier piles, unique water-sealing and water-isolating measures and carrier compaction control methods are adopted to ensure the molding efficiency and construction quality of the carrier even in soil layers rich in groundwater content.

[0007] The construction method of a carrier pile proposed in the present invention is suitable for engineering applications where the pile end carrier is below the groundwater level, and is characterized in that the steps include: 1) The lower opening of the prefabricated hollow tube body is sealed in advance with a bottom sealing member; 2) Sinking the sealed prefabricated hollow tube to a set depth at the pile position in the foundation; 3) A rammer is placed in the inner cavity of the prefabricated hollow tube through the upper opening of the prefabricated hollow tube. When the bottom end of the rammer sinks to contact the bottom seal of the prefabricated hollow tube, a position is marked on the rammer or a flexible rope connected to the rammer above the ground surface, and a cement-sand mixture is filled into the inner cavity to a predetermined height. The rammer is lifted to squeeze the cement-sand mixture with hammering energy capable of opening the bottom seal, thereby driving the cement-sand mixture to open the bottom seal; 4) Continue to fill the inner cavity of the prefabricated hollow tube with cement-sand mixture and tamp it with a rammer. During this process, the inner cavity is required to always contain cement-sand mixture, that is, the tamping position of the rammer bottom does not exceed the bottom end of the prefabricated hollow tube. The cement-sand mixture is controlled to be continuously squeezed out of the inner cavity and form a pile end carrier under the inner cavity. The pile end carrier plays a role of sealing and isolating water while compacting and reinforcing the soil around the pile end. 5) Continue to fill the cement-sand mixture into the inner cavity of the prefabricated hollow tube and gradually increase the hammering energy of the rammer to tamp the cement-sand mixture. Control the tamping position of the rammer bottom to gradually drop and be flush with the bottom end of the prefabricated hollow tube, so that the volume of the pile end carrier continues to increase; 6) After confirming that there is no water in the inner cavity of the prefabricated hollow tube body, continue to fill the inner cavity with cement-sand mixture and gradually increase the tamping energy of the tamping hammer to tamp the cement-sand mixture. Control the tamping position of the tamping hammer bottom to continue to drop and exceed the bottom end of the prefabricated hollow tube body, that is, perform the filling tamping operation outside the inner cavity of the prefabricated hollow tube body, so that the volume of the pile end carrier continues to increase; 7) Measure the three-strike penetration of the rammer. After the three-strike penetration meets the design requirements, continue to fill the inner cavity with cement-sand mixture, and use the rammer to tamp the cement-sand mixture with a tamping energy that does not exceed step 6), so that the tamping position of the bottom of the rammer gradually rises and is flush with the bottom end of the prefabricated hollow tube; or continue to fill the inner cavity with cement-sand mixture, and use the rammer to tamp, and use the rammer to tamp the cement-sand mixture with a tamping energy that does not exceed step 6), so that the tamping position of the bottom of the rammer gradually rises and is flush with the bottom end of the prefabricated hollow tube, and then measure the three-strike penetration of the rammer; 8) Fill the inner cavity of the prefabricated hollow tube with material to seal the bottom or tamp the filler to seal the bottom to prevent the pile end carrier filler from flowing back in the inner cavity.

[0008] Preferably, the prefabricated hollow pipe body comprises a prefabricated concrete pipe pile or a prefabricated hollow steel pipe, and the bottom cover comprises a bottom cover steel plate or a prefabricated pile tip.

[0009] Preferably, when a bottom sealing steel plate is used to seal the bottom of a prestressed concrete pipe pile, the diameter of the bottom sealing steel plate is larger than the diameter of the center hole of the prestressed concrete pipe pile and not larger than the outer diameter of the prestressed concrete pipe pile, the thickness of the bottom sealing steel plate is not less than 6 mm, the bottom sealing steel plate is fixed to the flange at the bottom end of the prestressed concrete pipe pile by bolts or welding, and the strength of the bolt or welding fixation is appropriately reduced to facilitate the bottom sealing steel plate to be driven away from the bottom end of the prestressed concrete pipe pile in subsequent processes; when a bottom sealing steel plate is used to seal the bottom of a hollow steel pipe, the diameter of the bottom sealing steel plate is not less than the outer diameter of the hollow steel pipe, the thickness of the bottom sealing steel plate is not less than 6 mm, the bottom sealing steel plate is fixed to the bottom opening of the hollow steel pipe by bolts or welding, and the strength of the bolt or welding fixation is appropriately reduced to facilitate the bottom sealing steel plate to be driven away from the bottom end of the hollow steel pipe in subsequent processes.

[0010] Preferably, when a prefabricated pile tip is used to seal the bottom of a prestressed concrete pipe pile, the prefabricated pile tip is prefabricated as a whole by a lower concrete pile tip and an upper flat steel plate, the diameter of the concrete pile tip is not greater than the diameter of the prestressed concrete pipe pile, the cross section is circular or polygonal, the lower concrete pile tip is a cone or a platform, the diameter of the upper flat steel plate is greater than the diameter of the central hole of the prestressed concrete pipe pile by more than 3 cm, after the prefabricated pile tip is concentrically aligned with the prestressed concrete pipe pile, the upper flat steel plate of the prefabricated pile tip is welded to the flange at the bottom of the prestressed concrete pipe pile, and the strength of the welding fixation is appropriately reduced. , so as to facilitate the prefabricated pile tip to be driven away from the bottom end of the prestressed concrete pipe pile in the subsequent process; when the prefabricated pile tip is used to seal the bottom of the hollow steel pipe, the prefabricated pile tip is prefabricated as a whole by the lower concrete pile tip and the upper flat steel plate, the diameter of the concrete pile tip is not less than the outer diameter of the hollow steel pipe, the cross-section is circular or polygonal, the lower concrete pile tip is a cone or a platform, after the prefabricated pile tip is concentrically aligned with the hollow steel pipe, the upper flat steel plate of the prefabricated pile tip is welded to the bottom of the hollow steel pipe as a whole, and the strength of the welding fixation is appropriately reduced, so as to facilitate the prefabricated pile tip to be driven away from the bottom end of the hollow steel pipe in the subsequent process.

[0011] It is best to use a bottom sealing steel plate or a prefabricated pile tip to seal the bottom of the prefabricated hollow tube body, and the bottom sealing steel plate or the prefabricated pile tip is fixed and sealed with the flange at the bottom end of the prestressed concrete pipe pile or the bottom of the hollow steel pipe by full welding. If spot welding or bolting is used for fixing and sealing, it is necessary to add a water-sealing rubber pad between the bottom sealing steel plate or the prefabricated pile tip and the bottom end of the prestressed concrete pipe pile or the bottom of the hollow steel pipe.

[0012] Preferably, in the above step 3), the inner cavity may be filled with a cement-sand mixture to a preset height, and then a rammer may be placed in the inner cavity.

[0013] Preferably, in the above step 3), when a rammer is placed in the inner cavity of the prefabricated hollow tube, the rammer should be slowly slid down with a brake or a stopper until the bottom end of the rammer contacts the bottom sealing member of the prefabricated hollow tube.

[0014] Preferably, in the above step 3), the preset height of the cement-sand mixture filled into the inner cavity of the prefabricated hollow tube is not less than 10 cm but not more than 1.5 m.

[0015] Preferably, when the above step 4) is completed and the step 5) is to be performed, the volume of the pile end carrier is not less than 0.2m3 to ensure the water sealing and water isolation effect.

[0016] Preferably, in the above steps 5) and 6), increasing the tamping energy of the tamping hammer is achieved by increasing the drop distance of the tamping hammer or increasing the weight of the tamping hammer.

[0017] Preferably, in the above steps 3) to 7), the change in the striking position of the bottom of the rammer is obtained by observing the relative change in the position of a mark on the rammer above the ground or on a flexible rope connected to the rammer.

[0018] Preferably, the grouting and bottom sealing described in step 8) above includes pouring micro-expansive cement mortar or high-strength grouting material or high-grade concrete into the inner cavity of the prefabricated hollow tube body, and the filler tamping and bottom sealing includes filling the inner cavity of the prefabricated hollow tube body with a cement-sand mixture to a height of not less than 0.5m and tamping it with a rammer to make it dense.

[0019] Preferably, the method further comprises the step of constructing the pile body after the step 8) is completed. The pile body construction comprises: when a prestressed concrete pipe pile is used, concrete is poured into the inner cavity of the prestressed concrete pipe pile; when a hollow steel pipe is used, a steel cage is sunk into the hollow steel pipe, pile body concrete is poured, and the hollow steel pipe is pulled out to form a pile; or after the hollow steel pipe is pulled out, a precast concrete pile body is implanted by hammering or static pressure with the pile hole as a guide; or a precast concrete pile body is implanted in the inner cavity of the hollow steel pipe and then the hollow steel pipe is pulled out to form a pile.

[0020] To achieve the above object, the present invention also proposes another method for constructing a carrier pile, which is also applicable to engineering applications where the pile end carrier is below the groundwater level. The method is characterized in that the density of the pile end carrier is controlled without using the three-hit penetration standard, and the steps include: 1) The lower opening of the prefabricated hollow tube body is sealed in advance with a bottom sealing member; 2) Sinking the sealed prefabricated hollow tube pile to the set depth at the pile position in the foundation; 3) A rammer is placed in the inner cavity of the prefabricated hollow tube through the upper opening of the prefabricated hollow tube. When the bottom end of the rammer sinks to contact the bottom seal of the prefabricated hollow tube, a position is marked on the rammer or a flexible rope connected to the rammer above the ground surface, and a cement-sand mixture is filled into the inner cavity to a predetermined height. The rammer is lifted to squeeze the cement-sand mixture with hammering energy capable of opening the bottom seal, thereby driving the cement-sand mixture to open the bottom seal; 4) Continue to fill the inner cavity of the prefabricated hollow tube with cement-sand mixture and tamp it with a rammer. During this process, the inner cavity is required to always contain cement-sand mixture, that is, the tamping position of the rammer bottom does not exceed the bottom end of the prefabricated hollow tube. The cement-sand mixture is controlled to be continuously squeezed out of the inner cavity and form a pile end carrier under the inner cavity. The pile end carrier plays a role of sealing and isolating water while compacting and reinforcing the soil around the pile end. 5) Continue the filling tamping operation in step 4) and keep the tamping position of the bottom of the tamping hammer within the bottom end of the prefabricated hollow tube until the filling amount of the cement sand mixture reaches the preset requirement. There is no need to measure the three-hit penetration; 6) Fill the inner cavity of the prefabricated hollow tube with material to seal the bottom or tamp the filler to seal the bottom to prevent the pile end carrier filler from flowing back in the inner cavity.

[0021] Preferably, the prefabricated hollow pipe body comprises a prefabricated concrete pipe pile or a prefabricated hollow steel pipe, and the bottom cover comprises a bottom cover steel plate or a prefabricated pile tip.

[0022] Preferably, when a bottom sealing steel plate is used to seal the bottom of a prestressed concrete pipe pile, the diameter of the bottom sealing steel plate is larger than the diameter of the center hole of the prestressed concrete pipe pile and not larger than the outer diameter of the prestressed concrete pipe pile, the thickness of the bottom sealing steel plate is not less than 6 mm, the bottom sealing steel plate is fixed to the flange at the bottom end of the prestressed concrete pipe pile by bolts or welding, and the strength of the bolt or welding fixation is appropriately reduced to facilitate the bottom sealing steel plate to be driven away from the bottom end of the prestressed concrete pipe pile in subsequent processes; when a bottom sealing steel plate is used to seal the bottom of a hollow steel pipe, the diameter of the bottom sealing steel plate is not less than the outer diameter of the hollow steel pipe, the thickness of the bottom sealing steel plate is not less than 6 mm, the bottom sealing steel plate is fixed to the bottom opening of the hollow steel pipe by bolts or welding, and the strength of the bolt or welding fixation is appropriately reduced to facilitate the bottom sealing steel plate to be driven away from the bottom end of the hollow steel pipe in subsequent processes.

[0023] Preferably, when a prefabricated pile tip is used to seal the bottom of a prestressed concrete pipe pile, the prefabricated pile tip is prefabricated as a whole by a lower concrete pile tip and an upper flat steel plate, the diameter of the concrete pile tip is not greater than the diameter of the prestressed concrete pipe pile, the cross section is circular or polygonal, the lower concrete pile tip is a cone or a platform, the diameter of the upper flat steel plate is greater than the diameter of the central hole of the prestressed concrete pipe pile by more than 3 cm, after the prefabricated pile tip is concentrically aligned with the prestressed concrete pipe pile, the upper flat steel plate of the prefabricated pile tip is welded to the flange at the bottom of the prestressed concrete pipe pile, and the strength of the welding fixation is appropriately reduced. , so as to facilitate the prefabricated pile tip to be driven away from the bottom end of the prestressed concrete pipe pile in the subsequent process; when the prefabricated pile tip is used to seal the bottom of the hollow steel pipe, the prefabricated pile tip is prefabricated as a whole by the lower concrete pile tip and the upper flat steel plate, the diameter of the concrete pile tip is not less than the outer diameter of the hollow steel pipe, the cross-section is circular or polygonal, the lower concrete pile tip is a cone or a platform, after the prefabricated pile tip is concentrically aligned with the hollow steel pipe, the upper flat steel plate of the prefabricated pile tip is welded to the bottom of the hollow steel pipe as a whole, and the strength of the welding fixation is appropriately reduced, so as to facilitate the prefabricated pile tip to be driven away from the bottom end of the hollow steel pipe in the subsequent process.

[0024] It is best to use a bottom sealing steel plate or a prefabricated pile tip to seal the bottom of the prefabricated hollow tube body, and the bottom sealing steel plate or the prefabricated pile tip is fixed and sealed with the flange at the bottom end of the prestressed concrete pipe pile or the bottom of the hollow steel pipe by full welding. If spot welding or bolting is used for fixing and sealing, it is necessary to add a water-sealing rubber pad between the bottom sealing steel plate or the prefabricated pile tip and the bottom end of the prestressed concrete pipe pile or the bottom of the hollow steel pipe.

[0025] Preferably, the cement sand mixture can be first filled into the inner cavity to a preset height, and then a rammer is placed into the inner cavity.

[0026] Preferably, when a rammer is placed in the inner cavity of the prefabricated hollow tube, the rammer should be slowly lowered with a brake or braking state until the bottom end of the rammer contacts the bottom sealing member at the bottom end of the prefabricated hollow tube.

[0027] Preferably, the preset height of the cement-sand mixture filled into the inner cavity of the prefabricated hollow tube is not less than 10 cm but not more than 1.5 m.

[0028] Preferably, in the above steps 4) and 5), the height of the cement-sand mixture filled into the inner cavity of the prefabricated hollow tube does not exceed 1.5 m.

[0029] Preferably, in step 5), the preset requirement for the filling amount of the cement sand mixture is determined according to the geological conditions and the bearing capacity requirements of the pile, and the filling amount range is controlled within 0.5m 3 Up to 2m 3 between.

[0030] Preferably, the grouting and bottom sealing described in step 8) above includes pouring micro-expansive cement mortar or high-strength grouting material or high-grade concrete into the inner cavity of the prefabricated hollow tube body, and the filler tamping and bottom sealing includes filling the inner cavity of the prefabricated hollow tube body with a cement-sand mixture to a height of not less than 0.5m and tamping it with a rammer to make it dense.

[0031] Preferably, the method further comprises constructing a pile body after the above step 8) is completed, wherein the pile body construction comprises: when a prestressed concrete pipe pile is used, concrete is poured into the inner cavity of the prestressed concrete pipe pile; when a hollow steel pipe is used, a steel cage is sunk into the hollow steel pipe, and then the pile body concrete is poured and the hollow steel pipe is pulled out to form a pile; or after the hollow steel pipe is pulled out, a precast concrete pile body is implanted by hammering or static pressure with the pile hole as a guide; or a precast concrete pile body is implanted in the inner cavity of the hollow steel pipe and then the hollow steel pipe is pulled out to form a pile.

[0032] The beneficial effects of the construction method of the carrier piles mentioned above are: ① emphasizing the pre-sealing treatment of the prefabricated hollow piles or hollow steel pipes, which effectively prevents the soil, especially water, in the foundation soil from entering the inner cavity during the sinking process, and can be easily and quickly detached by low-energy hammering after sinking into place, so as to facilitate the next step of process construction; ② During the entire construction process, whether it is when hammering to open the bottom seal or when continuously filling and tamping, the rammer cannot directly contact the soil at the pile end, but acts on the cement sand mixture. This method makes the cement sand mixture no longer simply a compacting and tamping medium, but also plays another role of sealing and isolating water. One method has two effects, thereby ensuring that the pile end carrier can still be quickly and effectively formed in strata with high groundwater content; ③ By observing the changes in the position of the mark on the wire rope connected to the rammer, the tamping position of the bottom of the rammer can be clearly and accurately controlled, and the tamping position of the bottom of the rammer is controlled to never exceed the bottom of the hollow pile or steel pipe, to the bottom. The core of the process is to require the volume of the pile end carrier to increase slowly and in a controlled manner; second, the rammer is required to not vibrate the soil at the pile end too much to avoid liquefaction; third, it is to ensure that water cannot enter the prefabricated hollow tube body to cause waste piles. This control process is specially designed for strata with high groundwater content; ④ If the groundwater content is really large and the water pressure is high, if the tamping position of the bottom of the rammer exceeds the bottom of the hollow pile or steel pipe for filling tamping, it may still be possible that the water cannot be sealed. Therefore, the present invention particularly proposes another construction method, which is operated while always maintaining a certain amount of cement-sand mixture in the inner cavity, and requires that the tamping position of the bottom of the rammer does not exceed the bottom of the prefabricated hollow pile or hollow steel pipe, and it is no longer required to detect the density of the carrier by three-hit penetration, but instead uses the filling amount of cement-sand mixture as the control standard, thereby improving the success rate of construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 1 is a schematic diagram of the process of one embodiment of the construction method of the carrier pile of the present invention. Figure 2 It is a process schematic diagram of the second embodiment.

[0034] Figure 1 Among them, 1 is a precast hollow pile, 2 is the inner cavity of the pipe pile, 3 is a rammer, 4 is a cement-sand mixture, 5 is a bottom steel plate, 6 is a steel wire rope, 7 is a pile end carrier, 8 is a slightly expansive cement mortar, 9 is concrete, 10 is a casing, 11 is a precast pile tip, and 12 is a steel cage. DETAILED DESCRIPTION

[0035] Figure 1 FIG. 1 is a schematic diagram of a process of an embodiment of a construction method of a carrier pile of the present invention. Figure 1 As shown in a, a bottom steel plate 5 is welded at the bottom of the prefabricated hollow pile 1; then, Figure 1As shown in b, the prefabricated hollow pile 1 is sunk into the foundation soil to the designed depth; then, Figure 1 c, slowly place the rammer 3 in the inner cavity 2 of the prefabricated hollow pile 1, and when the bottom end of the rammer 3 sinks to be level with the bottom end of the prefabricated hollow pile 1, that is, when the bottom end of the rammer 3 contacts the bottom steel plate 5, mark the position on the steel wire rope 6 connected to the rammer 3 above the ground surface; then, Figure 1 As shown in FIG. 4 , a cement-sand mixture 4 with a height of 50 cm is filled into the inner cavity 2, and the rammer 3 is lifted to lightly tamp the cement-sand mixture 4 with a drop distance of 2 m, so as to squeeze the cement-sand mixture and open the bottom steel plate 5; then, as shown in FIG. Figure 1 As shown in Figure e, the cement-sand mixture 4 is continuously filled into the inner cavity 2 and the rammer 3 is lifted to lightly tamp the cement-sand mixture 4 at a drop distance of no more than 3m. During this process, it is required that the cement-sand mixture 4 at a height of 30cm to 50cm is always maintained in the inner cavity, that is, the tamping position of the bottom of the rammer 3 does not exceed the bottom end of the prefabricated hollow pile 1, so that the cement-sand mixture 4 is continuously squeezed out of the inner cavity 2 and a pile end carrier 7 is formed under the inner cavity 2. The pile end carrier 7 plays a role of sealing and isolating water while compacting and reinforcing the soil around the pile end; then, as shown in Figure e, Figure 1 As shown in f, the volume of the carrier 7 at the pile end is greater than 0.5m 3 Then, the cement-sand mixture 4 is continuously filled into the inner cavity 2 and the drop distance of the rammer 3 is raised to 4 m, so that the ramming position of the bottom of the rammer 3 gradually drops and is flush with the bottom end of the prefabricated hollow pile 1, and the volume of the pile end carrier 7 continues to increase; then, as Figure 1 As shown in FIG. 6 , after observing and confirming that there is no water in the inner cavity 2, cement sand mixture 4 is continuously filled into the inner cavity 2 and the drop distance of the rammer 3 is increased to 5 m, so that the ramming position of the bottom of the rammer 3 continues to drop and exceeds the bottom end of the prefabricated hollow pile 1, and the volume of the pile end carrier 7 continues to increase; then, as shown in FIG. Figure 1 As shown in h, the penetration of the rammer 3 after three consecutive hammerings without filling is measured. After the three-hammer penetration meets the design requirements, the cement-sand mixture 4 is continuously filled into the inner cavity 2 and rammed with the rammer 3, so that the ramming position of the bottom of the rammer 3 gradually rises and is flush with the bottom end of the prefabricated hollow pile 1; then, as shown in Figure 1 As shown in FIG. 1 , a micro-expansion cement mortar 8 with a height of 1 m is poured into the inner cavity 2 of the prefabricated hollow pile 1; finally, as shown in FIG. Figure 1 As shown in FIG. 1 , concrete 9 is poured into the inner cavity 2 of the prefabricated hollow pile 1 to complete the construction of the pile.

[0036] Figure 2 Schematic diagram of the process of the second embodiment of the construction method of the carrier pile of the present invention. Figure 2 As shown in a, a prefabricated pile tip 11 is welded at the bottom of the casing 10; then, as shown in Figure 2 As shown in b, the casing 10 is sunk into the foundation soil to the designed depth; then, as shown in Figure 1c, slowly place the rammer 3 in the inner cavity of the casing 10, and when the bottom end of the rammer 3 sinks to be level with the bottom end of the casing 10, that is, when the bottom end of the rammer 3 contacts the prefabricated pile tip 11, mark the position on the wire rope 6 connected to the rammer 3 above the ground surface; then, Figure 2 As shown in FIG. 4 , a cement-sand mixture 4 with a height of 60 cm is filled into the inner cavity of the casing 10, and the rammer 3 is lifted to lightly tamp the cement-sand mixture 4 with a drop distance not exceeding 2.5 m, so as to squeeze the cement-sand mixture and open the prefabricated pile tip 11; then, as shown in FIG. Figure 1 As shown in Figure e, the cement-sand mixture 4 is continuously filled into the inner cavity of the casing 10 and the rammer 3 is lifted to lightly tamp the cement-sand mixture 4 at a drop distance not exceeding 2.5 m. During this process, it is required that the cement-sand mixture 4 at a height of 30 cm to 60 cm is always maintained in the inner cavity, that is, the tamping position of the bottom of the rammer 3 does not exceed the bottom end of the casing 10, so that the cement-sand mixture 4 is continuously squeezed out of the inner cavity of the casing 10 and a pile end carrier 7 is formed below the inner cavity. The pile end carrier 7 plays a role of sealing and isolating water while compacting and reinforcing the soil around the pile end; then, as shown in Figure e, the cement-sand mixture 4 is continuously squeezed out of the inner cavity of the casing 10 and forms a pile end carrier 7 below the inner cavity. The pile end carrier 7 plays a role of sealing and isolating water while compacting and reinforcing the soil around the pile end; then, Figure 2 As shown in f, by repeated filling and extrusion operations, the set 1.8m 3 The cement mixture 4 is completely tamped and filled, and finally the pile end carrier 7 is formed; then, Figure 2 As shown in FIG. 6 , a steel cage 12 is placed in the inner cavity of the casing 10, and then concrete 9 is poured to the foundation surface to complete the pile construction.

[0037] The above embodiments are merely illustrative rather than restrictive, and the protection scope of the present invention cannot be limited thereto. Other different forms of changes or modifications derived from the above descriptions are still within the protection scope of the present invention.

Claims

1. A method for constructing a carrier pile, which is suitable for engineering applications where the pile end carrier is below the groundwater level, and is characterized in that: The steps include: 1) The lower opening of the prefabricated hollow tube body is sealed in advance with a bottom sealing member; 2) Sinking the sealed prefabricated hollow pipe body to a set depth at the pile position in the foundation; 3) A rammer is placed in the inner cavity of the prefabricated hollow tube through the upper opening of the prefabricated hollow tube. When the bottom end of the rammer sinks to contact the bottom seal of the prefabricated hollow tube, a position is marked on the rammer or a flexible rope connected to the rammer above the ground surface, and a cement-sand mixture is filled into the inner cavity to a predetermined height. The rammer is lifted to squeeze the cement-sand mixture with hammering energy capable of opening the bottom seal, thereby driving the cement-sand mixture to open the bottom seal; 4) Continue to fill the inner cavity of the prefabricated hollow tube with cement-sand mixture and tamp it with a rammer. During this process, the inner cavity is required to always contain cement-sand mixture, that is, the tamping position of the rammer bottom does not exceed the bottom end of the prefabricated hollow tube. The cement-sand mixture is controlled to be continuously squeezed out of the inner cavity and form a pile end carrier under the inner cavity. The pile end carrier plays a role of sealing and isolating water while compacting and reinforcing the soil around the pile end. 5) Continue to fill the cement-sand mixture into the inner cavity of the prefabricated hollow tube and gradually increase the hammering energy of the rammer to tamp the cement-sand mixture. Control the tamping position of the rammer bottom to gradually drop and be flush with the bottom end of the prefabricated hollow tube, so that the volume of the pile end carrier continues to increase; 6) After confirming that there is no water in the inner cavity of the prefabricated hollow tube body, continue to fill the inner cavity with cement-sand mixture and gradually increase the tamping energy of the tamping hammer to tamp the cement-sand mixture. Control the tamping position of the tamping hammer bottom to continue to drop and exceed the bottom end of the prefabricated hollow tube body, that is, perform the filling tamping operation outside the inner cavity of the prefabricated hollow tube body, so that the volume of the pile end carrier continues to increase; 7) Measure the three-strike penetration of the rammer. After the three-strike penetration meets the design requirements, continue to fill the inner cavity with cement-sand mixture, and use the rammer to tamp the cement-sand mixture with a tamping energy that does not exceed step 6), so that the tamping position of the bottom of the rammer gradually rises and is flush with the bottom end of the prefabricated hollow tube; or continue to fill the inner cavity with cement-sand mixture, and use the rammer to tamp, and use the rammer to tamp the cement-sand mixture with a tamping energy that does not exceed step 6), so that the tamping position of the bottom of the rammer gradually rises and is flush with the bottom end of the prefabricated hollow tube, and then measure the three-strike penetration of the rammer; 8) Fill the inner cavity of the prefabricated hollow tube with material to seal the bottom or tamp the filler to seal the bottom to prevent the pile end carrier filler from flowing back in the inner cavity.

2. The construction method of carrier pile according to claim 1, characterized in that In the above step 1), the prefabricated hollow pipe body includes a prefabricated concrete pipe pile or a prefabricated hollow steel pipe, and the bottom cover includes a bottom cover steel plate or a prefabricated pile tip.

3. The construction method of carrier pile according to claim 1 or 2, characterized in that: When a bottom sealing steel plate is used to seal the bottom of a prestressed concrete pile, the diameter of the bottom sealing steel plate shall be greater than the diameter of the center hole of the prestressed concrete pile and not greater than the outer diameter of the prestressed concrete pile, the thickness of the bottom sealing steel plate shall not be less than 6 mm, the bottom sealing steel plate shall be fixed to the flange at the bottom end of the prestressed concrete pile by bolts or welding, and the strength of the bolt or welding fixation shall be appropriately reduced to facilitate the bottom sealing steel plate to be driven away from the bottom end of the prestressed concrete pile in subsequent processes; when a bottom sealing steel plate is used to seal the bottom of a hollow steel pipe, the diameter of the bottom sealing steel plate shall not be less than the outer diameter of the hollow steel pipe, the thickness of the bottom sealing steel plate shall not be less than 6 mm, the bottom sealing steel plate shall be fixed to the bottom of the hollow steel pipe by bolts or welding, and the strength of the bolt or welding fixation shall be appropriately reduced to facilitate the bottom sealing steel plate to be driven away from the bottom end of the hollow steel pipe in subsequent processes.

4. The construction method of carrier pile according to claim 1 or 2, characterized in that: When prefabricated pile tips are used to seal the bottom of prestressed concrete pipe piles, the prefabricated pile tips are prefabricated as a whole by the lower concrete pile tip and the upper flat steel plate. The diameter of the concrete pile tip is not greater than the diameter of the prestressed concrete pipe pile, and the cross-section is circular or polygonal. The lower concrete pile tip is a cone or a table. The diameter of the upper flat steel plate is greater than the diameter of the center hole of the prestressed concrete pipe pile by more than 3 cm. After the prefabricated pile tip is concentrically aligned with the prestressed concrete pipe pile, the upper flat steel plate of the prefabricated pile tip is welded to the flange at the bottom of the prestressed concrete pipe pile. The strength of the welding fixation is appropriately reduced. This is to facilitate the prefabricated pile tip to be driven away from the bottom end of the prestressed concrete pipe pile in the subsequent process; when the prefabricated pile tip is used to seal the bottom of the hollow steel pipe, the prefabricated pile tip is prefabricated as a whole by the lower concrete pile tip and the upper flat steel plate, the diameter of the concrete pile tip is not less than the outer diameter of the hollow steel pipe, the cross-section is circular or polygonal, the lower concrete pile tip is a cone or a platform, after the prefabricated pile tip is concentrically aligned with the hollow steel pipe, the upper flat steel plate of the prefabricated pile tip is welded to the bottom of the hollow steel pipe as a whole, and the strength of the welding fixation is appropriately reduced, so as to facilitate the prefabricated pile tip to be driven away from the bottom end of the hollow steel pipe in the subsequent process.

5. The construction method of carrier pile according to claim 1 or 2, characterized in that: When a bottom sealing steel plate or a prefabricated pile tip is used to seal the bottom of the prefabricated hollow pipe body, the bottom sealing steel plate or the prefabricated pile tip is fixedly sealed with the flange at the bottom end of the prestressed concrete pipe pile or the bottom of the hollow steel pipe by full welding. If spot welding or bolting is used for fixing and sealing, it is necessary to add a water-sealing rubber pad between the bottom sealing steel plate or the prefabricated pile tip and the bottom end of the prestressed concrete pipe pile or the bottom of the hollow steel pipe.

6. The construction method of carrier pile according to claim 1, characterized in that In the above step 3), the inner cavity may be filled with a cement-sand mixture to a preset height, and then a rammer may be placed in the inner cavity.

7. The construction method of carrier pile according to claim 1, characterized in that In the above step 3), when a rammer is placed in the inner cavity of the prefabricated hollow tube, the rammer should be slid and slowly sunk with a brake or a stopper until the bottom end of the rammer contacts the bottom sealing member of the prefabricated hollow tube.

8. The construction method of carrier pile according to claim 1, characterized in that In the above step 3), the preset height of the cement sand mixture filled into the inner cavity of the prefabricated hollow tube is not less than 10 cm but not more than 1.5 m.

9. The construction method of carrier pile according to claim 1, characterized in that At the end of step 4) and before step 5), the volume of the pile end carrier shall not be less than 0.2m 3 To ensure the water sealing and waterproofing effect.

10. The construction method of carrier pile according to claim 1, characterized in that In the above steps 5) and 6), increasing the tamping energy of the tamping hammer is achieved by increasing the drop distance of the tamping hammer or increasing the weight of the tamping hammer.

11. The construction method of carrier pile according to claim 1, characterized in that In the above steps 3) to 7), the change of the tamping position of the bottom of the tamping hammer is obtained by observing the relative change of the position of the mark on the tamping hammer or the flexible rope connected to the tamping hammer above the ground surface.

12. The construction method of carrier pile according to claim 1 or 2, characterized in that The grouting and bottom sealing described in the above step 8) includes pouring micro-expansive cement mortar or high-strength grouting material or high-grade concrete into the inner cavity of the prefabricated hollow tube body, and the filler tamping and bottom sealing includes filling the inner cavity of the prefabricated hollow tube body with a cement sand mixture of not less than 0.5m in height and tamping it with a rammer to make it dense.

13. The construction method of carrier pile according to claim 1 or 2, characterized in that: The method further includes the following steps: after the above step 8) is completed, the pile body construction includes: when a prestressed concrete pipe pile is used, concrete is poured into the inner cavity of the prestressed concrete pipe pile; when a hollow steel pipe is used, a steel cage is sunk into the hollow steel pipe, and then the pile body concrete is poured and the hollow steel pipe is pulled out to form a pile; or after the hollow steel pipe is pulled out, a precast concrete pile body is implanted by hammering or static pressure with the pile hole as a guide; or a precast concrete pile body is implanted in the inner cavity of the hollow steel pipe and then the hollow steel pipe is pulled out to form a pile.

14. A method for constructing a carrier pile, which is suitable for engineering applications where the pile end carrier is below the groundwater level, characterized in that: The steps include: 1) The lower opening of the prefabricated hollow tube body is sealed in advance with a bottom sealing member; 2) Sinking the sealed prefabricated hollow tube pile to the set depth at the pile position in the foundation; 3) A rammer is placed in the inner cavity of the prefabricated hollow tube through the upper opening of the prefabricated hollow tube. When the bottom end of the rammer sinks to contact the bottom seal of the prefabricated hollow tube, a position is marked on the rammer or a flexible rope connected to the rammer above the ground surface, and a cement-sand mixture is filled into the inner cavity to a predetermined height. The rammer is lifted to squeeze the cement-sand mixture with hammering energy capable of opening the bottom seal, thereby driving the cement-sand mixture to open the bottom seal; 4) Continue to fill the inner cavity of the prefabricated hollow tube with cement-sand mixture and tamp it with a rammer. During this process, the inner cavity is required to always contain cement-sand mixture, that is, the tamping position of the rammer bottom does not exceed the bottom end of the prefabricated hollow tube. The cement-sand mixture is controlled to be continuously squeezed out of the inner cavity and form a pile end carrier under the inner cavity. The pile end carrier plays a role of sealing and isolating water while compacting and reinforcing the soil around the pile end. 5) Continue the filling tamping operation in step 4) and keep the tamping position of the bottom of the tamping hammer within the bottom end of the prefabricated hollow tube until the filling amount of the cement sand mixture reaches the preset requirement. There is no need to measure the three-hit penetration; 6) Fill the inner cavity of the prefabricated hollow tube with material to seal the bottom or tamp the filler to seal the bottom to prevent the pile end carrier filler from flowing back in the inner cavity.

15. The construction method of carrier pile according to claim 14, characterized in that In the above step 1), the prefabricated hollow pipe body includes a prefabricated concrete pipe pile or a prefabricated hollow steel pipe, and the bottom cover includes a bottom cover steel plate or a prefabricated pile tip.

16. The construction method of carrier piles according to claim 14 or 15, characterized in that: When a bottom sealing steel plate is used to seal the bottom of a prestressed concrete pile, the diameter of the bottom sealing steel plate shall be greater than the diameter of the center hole of the prestressed concrete pile and not greater than the outer diameter of the prestressed concrete pile, the thickness of the bottom sealing steel plate shall not be less than 6 mm, the bottom sealing steel plate shall be fixed to the flange at the bottom end of the prestressed concrete pile by bolts or welding, and the strength of the bolt or welding fixation shall be appropriately reduced to facilitate the bottom sealing steel plate to be driven away from the bottom end of the prestressed concrete pile in subsequent processes; when a bottom sealing steel plate is used to seal the bottom of a hollow steel pipe, the diameter of the bottom sealing steel plate shall not be less than the outer diameter of the hollow steel pipe, the thickness of the bottom sealing steel plate shall not be less than 6 mm, the bottom sealing steel plate shall be fixed to the bottom of the hollow steel pipe by bolts or welding, and the strength of the bolt or welding fixation shall be appropriately reduced to facilitate the bottom sealing steel plate to be driven away from the bottom end of the hollow steel pipe in subsequent processes.

17. The construction method of carrier piles according to claim 14 or 15, characterized in that: When prefabricated pile tips are used to seal the bottom of prestressed concrete pipe piles, the prefabricated pile tips are prefabricated as a whole by the lower concrete pile tip and the upper flat steel plate. The diameter of the concrete pile tip is not greater than the diameter of the prestressed concrete pipe pile, and the cross-section is circular or polygonal. The lower concrete pile tip is a cone or a table. The diameter of the upper flat steel plate is greater than the diameter of the center hole of the prestressed concrete pipe pile by more than 3 cm. After the prefabricated pile tip is concentrically aligned with the prestressed concrete pipe pile, the upper flat steel plate of the prefabricated pile tip is welded to the flange at the bottom of the prestressed concrete pipe pile. The strength of the welding fixation is appropriately reduced. This is to facilitate the prefabricated pile tip to be driven away from the bottom end of the prestressed concrete pipe pile in the subsequent process; when the prefabricated pile tip is used to seal the bottom of the hollow steel pipe, the prefabricated pile tip is prefabricated as a whole by the lower concrete pile tip and the upper flat steel plate, the diameter of the concrete pile tip is not less than the outer diameter of the hollow steel pipe, the cross-section is circular or polygonal, the lower concrete pile tip is a cone or a platform, after the prefabricated pile tip is concentrically aligned with the hollow steel pipe, the upper flat steel plate of the prefabricated pile tip is welded to the bottom of the hollow steel pipe as a whole, and the strength of the welding fixation is appropriately reduced, so as to facilitate the prefabricated pile tip to be driven away from the bottom end of the hollow steel pipe in the subsequent process.

18. The construction method of carrier piles according to claim 14 or 15, characterized in that: When a bottom sealing steel plate or a prefabricated pile tip is used to seal the bottom of the prefabricated hollow pipe body, the bottom sealing steel plate or the prefabricated pile tip is fixedly sealed with the flange at the bottom end of the prestressed concrete pipe pile or the bottom of the hollow steel pipe by full welding. If spot welding or bolting is used for fixing and sealing, it is necessary to add a water-sealing rubber pad between the bottom sealing steel plate or the prefabricated pile tip and the bottom end of the prestressed concrete pipe pile or the bottom of the hollow steel pipe.

19. The construction method of carrier pile according to claim 14, characterized in that In the above step 3), the inner cavity may be filled with a cement-sand mixture to a preset height, and then a rammer may be placed in the inner cavity.

20. The construction method of carrier pile according to claim 14, characterized in that In the above step 3), when a rammer is placed in the inner cavity of the prefabricated hollow tube, the rammer should be slid and slowly sunk with a brake or a stopper until the bottom end of the rammer contacts the bottom sealing member of the prefabricated hollow tube.

21. The construction method of carrier pile according to claim 14, characterized in that In the above step 3), the preset height of the cement sand mixture filled into the inner cavity of the prefabricated hollow tube is not less than 10 cm but not more than 1.5 m.

22. The construction method of carrier pile according to claim 14, characterized in that In the above steps 4) and 5), the height of the cement-sand mixture filled into the inner cavity of the prefabricated hollow tube does not exceed 1.5 m.

23. The construction method of carrier pile according to claim 14 or 15, characterized in that The grouting and bottom sealing described in the above step 8) includes pouring micro-expansive cement mortar or high-strength grouting material or high-grade concrete into the inner cavity of the prefabricated hollow tube body, and the filler tamping and bottom sealing includes filling the inner cavity of the prefabricated hollow tube body with a cement sand mixture of not less than 0.5m in height and tamping it with a rammer to make it dense.

24. The construction method of carrier pile according to claim 14, characterized in that In the above step 5), the preset requirement for the filling amount of cement sand mixture is determined according to the geological conditions and the bearing capacity requirements of the piles, and the filling amount range is controlled within 0.5m 3 Up to 2m 3 between.

25. The construction method of carrier piles according to claim 14 or 15, characterized in that: The method further includes constructing a pile body after the above step 8) is completed. The pile body construction includes: when a prestressed concrete pipe pile is used, concrete is poured into the inner cavity of the prestressed concrete pipe pile; when a hollow steel pipe is used, a steel cage is sunk into the hollow steel pipe, and then the pile body concrete is poured and the hollow steel pipe is pulled out to form a pile; or after the hollow steel pipe is pulled out, a precast concrete pile body is implanted by hammering or static pressure with the pile hole as a guide; or a precast concrete pile body is implanted in the inner cavity of the hollow steel pipe and then the hollow steel pipe is pulled out to form a pile.

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