A precast pipe pile, a construction method of the precast pipe pile and a pile foundation structure

Abstract

The present invention discloses a precast pipe pile, a construction method of the precast pipe pile and a pile foundation structure. The method comprises the following steps: inserting a pile plug into the end of a hollow pipe pile body to form a precast pipe pile, and pressing the precast pipe pile into the soil at a preset depth; putting a permeable bag filled with a high water-stop filler into the pipe pile body, and compacting the permeable bag in the pipe pile body to form a water-stop plug on the pile plug, continuously feeding and compacting until the preset water-stop condition is met; pressing the water-stop plug to separate the pile plug from the pipe pile body, and feeding filler into the pipe pile body until the preset termination condition is met. In this method, the high water-stop filler filled can avoid the occurrence of piping phenomenon, and the subsequent formed water-stop plug can play the role of absorbing water and physically blocking the entry of soft mud; by adopting an extrusion-expansion guiding type and an opening-closing type pile tip, a laterally extruded and expanded reinforcement body can be formed at the pile end of the pipe pile in a saturated soft soil layer, solving the problems of poor water-stop ability and insufficient bearing capacity improvement during the early-stage filler reinforcement process in the saturated soft soil layer.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering, and particularly to a precast pipe pile, a construction method thereof, and a pile foundation structure. Background Art

[0002] In the field of building pile foundations, high-strength precast pipe piles processed by factory prefabrication are gradually applied to various buildings due to their advantages such as high pile body strength, stable quality, high single-pile bearing capacity, short construction period, and low cost. When using precast pipe piles for construction in coastal water-rich soft soil strata, there are problems such as low bearing capacity of the pipe piles, and even the phenomenon of pile sinking. Increasing the pile length or pile diameter significantly will lead to problems such as increased pile sinking resistance, excessive cost, and damage to the pile tip. Therefore, considering strengthening the pile tip of the precast pipe pile and improving the pile tip bearing capacity is an economically feasible method to overall improve the bearing capacity of the precast pipe pile.

[0003] During the construction process, it is found that in a soil environment with a very high groundwater level and large water pressure, there is an easy problem of poor water sealing ability during the pre-filling reinforcement process of the pipe pile. The specific manifestations are as follows: Due to the limited filling speed of the gap filling method, part of the loose filler adheres to the upper part of the rammer and the inner wall of the precast pipe pile hole. During the filling process, the water sealing effect at the pile bottom is insufficient. After the soil at the pile bottom of the pipe pile is disturbed by the impact, a large amount of water and soft mud pour into the inside of the pipe pile, resulting in the inability to continue ramming to form an enlarged pile bottom, or there is a soft mud interlayer in the enlarged head formed by the filling reinforcement.

[0004] In addition, field tests have found that when ramming and filling the pile tip of precast pipe piles in water-rich soft soil strata, the formed pile tip reinforcement body always tends to expand downward, and the lateral expansion effect is insufficient, resulting in little increase in the bearing capacity of the pile tip reinforcement piles of small and medium-diameter precast pipe piles, and the bearing capacity of the pile tips of the precast pipe piles after construction reinforcement has not been significantly improved. Summary of the Invention

[0005] The present invention provides a precast pipe pile, a construction method thereof, and a pile foundation structure, aiming to solve the problem of poor water sealing ability during the pre-filling reinforcement process in the prior art.

[0006] A construction method of a precast pipe pile provided in the first aspect of the present invention includes the following steps:

[0007] Insert a pile plug at the end of a hollow pipe pile body to form a precast pipe pile, and press the precast pipe pile into the soil at a preset depth;

[0008] Put a water-permeable bag filled with a high-water-sealing filler into the pipe pile body, and compact the water-permeable bag in the pipe pile body to form a water-sealing plug on the pile plug. Continuously feed and compact until the preset water-sealing condition is met, wherein the pile plug remains inserted on the pipe pile body;

[0009] Press the water sealing plug to separate the pile plug from the pipe pile body, and put filling materials into the pipe pile body until the preset termination condition is met.

[0010] In some embodiments of the first aspect, the components of the high water-stop filling material include dry quicklime, dry secondary bottom slag fine sand from waste incineration, and a mixture of dry cement and secondary bottom slag fine sand from waste incineration;

[0011] The method of loading the high water-stop filling material into the permeable bag includes the following steps:

[0012] First, load the quicklime into the permeable bag;

[0013] Then, load the secondary bottom slag fine sand from waste incineration into the permeable bag;

[0014] Finally, load the mixture of cement and secondary bottom slag fine sand from waste incineration into the permeable bag.

[0015] In some embodiments of the first aspect, the volume of the quicklime is 1 / 10 - 1 / 6 of the volume of the permeable bag;

[0016] The volume of the secondary bottom slag fine sand from waste incineration is 1 / 3 - 1 / 2 of the volume of the permeable bag;

[0017] The volume of the mixture of cement and secondary bottom slag fine sand from waste incineration is 1 / 3 - 1 / 2 of the volume of the permeable bag, and the mass ratio of cement to secondary bottom slag fine sand from waste incineration in the mixture is 1:3 - 1:5.

[0018] In some embodiments of the first aspect, in the step of putting the permeable bag filled with high water-stop filling material into the pipe pile body, the outer peripheral side of a single permeable bag abuts against the inner peripheral wall of the pipe pile body.

[0019] In some embodiments of the first aspect, the permeable bag is a woven mesh bag.

[0020] In some embodiments of the first aspect, the height of the water sealing plug is 5 - 30 cm.

[0021] In some embodiments of the first aspect, the preset water-stop condition is that the water content at the top of the water sealing plug is less than a preset value.

[0022] In some embodiments of the first aspect, in the step of putting filling materials into the pipe pile body until the preset termination condition is met, specifically:

[0023] Put the bearing layer reinforcement filling material into the pipe pile body until the first preset termination condition is met;

[0024] Put core filling material into the pipe pile body until the second preset termination condition is met.

[0025] In some embodiments of the first aspect, in the step of putting bearing layer reinforcement filling material into the pipe pile body until the first preset termination condition is met, specifically:

[0026] Put an impermeable bag filled with bearing layer reinforcement filling material into the pipe pile body until the first preset termination condition is met.

[0027] In some embodiments of the first aspect, the components of the bearing layer reinforcement filling material include dry-hardened cement mortar and gravel, and the mass ratio of the dry-hardened cement mortar to the gravel is 1:1 to 1:2.5, and the particle size of the gravel is less than or equal to 6 mm;

[0028] The components of the dry-hardened cement mortar include water, cement and secondary bottom slag from waste incineration, and the mass ratio of the cement to the secondary bottom slag from waste incineration is 1:3 to 1:5.

[0029] The second aspect of the present invention provides a precast pipe pile, which is applied to the precast pipe pile construction method described in the first aspect, and includes a hollow pipe pile body, a pile plug and a seal;

[0030] The pile plug is inserted into the end of the pipe pile body; the pile plug can be separated from the pipe pile body after being subjected to a preset pressure;

[0031] The seal can be elastically clamped between the pipe pile body and the pile plug.

[0032] In some embodiments of the second aspect, the precast pipe pile further includes a plurality of lifting ropes;

[0033] One end of the lifting rope is fixedly connected to the pipe pile body, and the other end of the lifting rope is fixedly connected to the pile plug.

[0034] In some embodiments of the second aspect, the pile plug has an extrusion expansion guiding section, and along the direction from the pipe pile body to the pile plug, the pile diameter of the extrusion expansion guiding section gradually becomes larger.

[0035] In some embodiments of the second aspect, along the direction from the pipe pile body to the pile plug, the pile plug sequentially includes an upper extrusion expansion guiding section, a platform section and a lower extrusion expansion guiding section;

[0036] The maximum pile diameter of the upper extrusion expansion guiding section is less than or equal to the minimum pile diameter of the lower extrusion expansion guiding section;

[0037] The platform section is used to clamp the pile plug on the pipe pile body.

[0038] In some embodiments of the second aspect, the pile plug includes a connecting seat and a plurality of pile petals. The plurality of pile petals are arranged on the circumferential side of the connecting seat. The pile petals are hinged to the connecting seat, and the plurality of pile petals can be turned over to surround the connecting seat or can be turned over and unfolded.

[0039] In some embodiments of the second aspect, the precast pipe pile further includes a bladder cap;

[0040] The bladder cap includes a cap body and a brim;

[0041] A circle of the brim is connected to the circumferential side of the cap body;

[0042] The cap body is sleeved above the pile plug, and the brim is fixedly connected to the pipe pile body.

[0043] A third aspect of the present invention provides a pile foundation structure, which is constructed by applying the precast pipe pile described in the second aspect to the precast pipe pile construction method described in the first aspect.

[0044] From the above technical solutions, it can be seen that the present invention has the following advantages:

[0045] This embodiment provides a precast pipe pile construction method. Since in this method, a permeable bag filled with a high water-stop filler is put into the pipe pile body, the filler in the permeable bag after filling will not scatter in the pipe pile body, preventing the filler put in bulk from being directly lifted by the pressure water due to its too small dry density, thus avoiding the occurrence of piping phenomenon. And since the pile plug remains inserted on the pipe pile body and compresses the filled permeable bag in the pipe pile body, a water-sealing plug will be formed on the pile plug. Therefore, the water-sealing plug is equivalent to a water-absorbing plug formed at the end of the pipe pile body. The filler in the water-sealing plug can absorb a large amount of water, preventing a large amount of water from pouring into the hollow interior of the precast pipe pile, and the water-sealing plug can also play a role in physically blocking the entry of soft mud, effectively solving the problem of poor water-sealing ability in the prior art during the early stage of filler reinforcement.

[0046] This embodiment provides a pile foundation structure. When reinforcing the pile end filler in the existing water-rich soft soil stratum, due to the insufficient constraint ability of the lower stratum, most of the filler is vertically filled in the lower part of the precast pipe pile, and the diameter of the formed reinforcement body does not exceed the diameter of the precast pipe pile, resulting in a relatively low increase ratio of the bearing capacity of the reinforced pile. In the pile foundation structure of this embodiment, the extrusion-expansion guiding type and opening-closing type pile tips are adopted, which can guide the filler to radially fill into the precast pipe pile during the filler reinforcement process; it is beneficial to form a large-volume reinforcement body with lateral extrusion-expansion at the pile end of the pipe pile in the saturated soft soil stratum, and the formed pile foundation structure can significantly improve the bearing capacity of the reinforced pile. Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0048] Figure 1 It is a schematic flow chart of a construction method for precast pipe piles provided in the first aspect of the embodiments of the present invention;

[0049] Figure 2 It is a schematic diagram of the construction process of a construction method for precast pipe piles provided in the first aspect of the embodiments of the present invention;

[0050] Figure 3 It is a schematic diagram of the overall structure of a precast pipe pile with a lifting rope provided in the second aspect of the embodiments of the present invention;

[0051] Figure 4 It is a schematic diagram of the structure of an upper hinged opening and closing pile plug provided in the second aspect of the embodiments of the present invention;

[0052] Figure 5 It is a schematic diagram of the unfolded structure of an upper hinged opening and closing pile plug provided in the second aspect of the embodiments of the present invention;

[0053] Figure 6 It is a schematic diagram of the structure of a connecting seat provided in the second aspect of the embodiments of the present invention;

[0054] Figure 7 It is a schematic diagram of the structure of an upper hinged opening and closing pile flap provided in the second aspect of the embodiments of the present invention;

[0055] Figure 8 It is a schematic diagram of the structure of a lower hinged opening and closing pile plug provided in the second aspect of the embodiments of the present invention;

[0056] Figure 9 It is a schematic diagram of the structure of a lower hinged opening and closing pile flap provided in the second aspect of the embodiments of the present invention;

[0057] Figure 10 It is a schematic diagram of the structure of a seal provided in the second aspect of the embodiments of the present invention;

[0058] Figure 11 It is a schematic diagram of the overall structure of a precast pipe pile with a bladder cap provided in the second aspect of the embodiments of the present invention;

[0059] Figure 12 It is a schematic diagram of the structure of a pile foundation structure with a lifting rope provided in the third aspect of the embodiments of the present invention;

[0060] Figure 13It is a schematic structural diagram of a pile foundation structure with a pocket cap provided in the third aspect of the embodiment of the present invention.

[0061] Reference numerals:

[0062] 1, pipe pile body; 2, pile plug; 20, upper squeezing and expanding guiding section; 21, platform stage; 22, lower squeezing and expanding guiding section; 23, connecting seat; 24, pile flap; 25, pocket cap; 3, seal; 4, lifting rope; 5, high water-stop filler; 6, pile foundation structure; a, squeezed and consolidated solid; b, compacted soil mass; c, affected soil mass. Specific embodiments

[0063] To make the objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0064] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and drawings of the present application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0065] In the precast pipe piles and construction methods in water-rich soft soil strata, it is found that there is a problem of poor water sealing ability during the precast pipe pile filling and reinforcement process in the early stage. Due to the limited filling speed of the gap filling method, some loose fillers adhere to the upper part of the rammer and the inner wall of the precast pipe pile hole. During the filling process, the water sealing effect at the bottom of the pile is insufficient. After the soil at the bottom of the pipe pile is disturbed by the impact, a large amount of water and soft mud pour into the pipe pile, resulting in the inability to continue ramming to form an enlarged head at the bottom of the pile, or there is a soft mud interlayer in the enlarged head formed by the filling and reinforcement. It is necessary to enhance the water sealing ability during the reinforcement process and improve the quality of the solid at the bottom of the pile.

[0066] In addition, the research also found that when precast pipe piles with small and medium diameters are reinforced by ramming fillers at the pile ends in water-rich soft soil strata, the pile-end reinforced bodies formed always tend to expand downward, while the lateral expansion effect of the reinforced bodies is insufficient, resulting in limited improvement in the bearing capacity of the precast pipe piles with small and medium diameters at the pile ends. Therefore, it is urgent to increase the lateral expansion ability of the expanded reinforced bodies.

[0067] The embodiment of the present invention provides a construction method for precast pipe piles to solve the technical problem of poor water sealing ability in the prior art during the early-stage filler reinforcement process.

[0068] Please refer to Figure 1 and Figure 2 , a construction method for precast pipe piles provided in this embodiment includes the following steps:

[0069] S1. Insert a pile plug 2 at the end of the hollow pipe pile body 1 to form a precast pipe pile, and press the precast pipe pile into the soil at a preset depth. Among them, the pile plug 2 can be separated from the pipe pile body 1 after being subjected to a preset pressure.

[0070] S2. Put a water-permeable bag filled with a high-water-sealing filler 5 into the pipe pile body 1, and compact the water-permeable bag filled in the pipe pile body 1 to form a water-sealing plug on the pile plug 2. Continuously feed materials and compact until the preset water-sealing condition is met. Among them, the pile plug 2 remains inserted on the pipe pile body 1.

[0071] S3. Press the water-sealing plug to separate the pile plug 2 from the pipe pile body 1, and feed fillers into the pipe pile body 1 until the preset termination condition is met.

[0072] In this embodiment, the pile plug 2 is inserted at the end of the pipe pile body 1 to form a precast pipe pile, and the precast pipe pile is pressed into the soil at a preset depth. Therefore, the precast pipe pile forms a structure with one end closed and one end open, so as to perform water-sealing treatment during the early-stage filling; put the water-permeable bag filled with the high-water-sealing filler 5 into the pipe pile body 1. Since the high-water-sealing filler 5 is loaded into the water-permeable bag and then put into the pipe pile body 1, the high-water-sealing filler 5 will not be scattered in the pipe pile body 1, and its dry density will not be too small and directly lifted by the pressure water, which can avoid the occurrence of piping phenomenon; after compacting the water-permeable bag on the pile plug 2 to form a water-sealing plug, the high-water-sealing filler 5 in the water-sealing plug can continuously absorb water, and the cooperation between the water-sealing plug and the pile plug 2 can block the entry of soft mud, avoiding the appearance of a soft mud layer inside the pipe pile body 1; press the water-sealing plug to separate the pile plug 2 from the pipe pile body 1, and feed fillers into the pipe pile body 1 until the preset termination condition is met to form a pile foundation structure 6.

[0073] Compared with the prior art, it has the following advantages: First, it can avoid the occurrence of piping phenomenon. That is, in this embodiment, the bagged high-water-stop filler 5 is put into the pipe pile body 1. Compared with the existing bulk lime input, on the one hand, it can prevent the lime input in bulk from being directly lifted due to its too small dry density, thus causing the piping phenomenon. On the other hand, it can slow down the speed of water flowing into the lime and avoid the gradual accumulation of a soft mud layer in the hollow of the precast pipe pile during the reinforcement process, thereby affecting the tamping energy. Second, it can absorb water sufficiently and block the entry of soft mud. When filling the water-stop material, the pile plug 2 is kept on the pipe pile body 1, and the high-water-stop filler 5 can form a water-stop plug inside the pipe pile body 1. The high-water-stop filler 5 in the water-stop plug can give full play to its water absorption performance. The cooperation of the water-stop plug and the pile plug 2 can physically block the influx of soft mud. Thus, it can be seen that this embodiment can effectively solve the technical problems such as a large amount of water and soft mud flowing into the pipe pile due to the high groundwater level in the water-rich soft soil stratum, resulting in the inability to continue tamping to form a pile bottom reinforcement body or the serious mud inclusion in the reinforcement body formed by the conventional tamping reinforcement method.

[0074] Through this technical solution, the traditional carrier pile and pile tip reinforcement construction technology can be promoted to water-rich soft soil construction sites such as coastal areas, and it has good application prospects.

[0075] As an example, as Figure 2 shown, a realizable way to press the precast pipe pile into the soil in step S1 is further provided. The way to press the precast pipe pile into the soil to a preset depth can adopt methods such as static pressure and hammering. When the designed pile top elevation of the precast pipe pile is lower than the ground elevation, a pile cap can be installed on the pile top of the precast pipe pile to assist the construction tool in pressing the precast pipe pile into the designed depth.

[0076] As an example, as Figure 2 shown, a realizable way in step S2 is further provided. In the whole step S2, the pile plug 2 is kept inserted into the pipe pile body 1. Step S2 specifically includes the following steps:

[0077] S20, put the permeable bag filled with the high-water-stop filler 5 into the pipe pile body 1.

[0078] In one embodiment, in order to meet the purposes of sufficient water absorption and maintaining the material structure strength, the components of the high-water-stop filler 5 include dry quicklime, dry secondary bottom slag fine sand from waste incineration, and a mixture of dry cement and secondary bottom slag fine sand from waste incineration. The method of loading the high-water-stop filler 5 into the permeable bag specifically includes the following steps: First, load the quicklime into the permeable bag; then, load the secondary bottom slag fine sand from waste incineration into the permeable bag; finally, load the mixture of cement and secondary bottom slag fine sand from waste incineration into the permeable bag.

[0079] In specific implementation, after the high water-stop filler 5 is filled into the permeable bag in the above order, a three-layer water-absorbing structure will be formed in the permeable bag. The first layer is quicklime, the second layer is fine sand of the secondary bottom slag from waste incineration, and the third layer is a mixture of cement and fine sand of the secondary bottom slag from waste incineration. After forming this three-layer structure, the advantages of each layer structure are as follows:

[0080] The first layer is quicklime. Quicklime itself has good water absorption performance, but its stacking state when dry is very loose. Firstly, it cannot be compacted by ramming. Secondly, because the lime is too light in specific gravity in the loose stacking state, under the action of pressurized water, the lime will not play a water absorption role simultaneously. Through research, it is found that when filling a cylinder with lime and applying water pressure inward at the bottom of the cylinder, it can be found that when clear water first appears on the upper surface of the cylinder, it is similar to the emergence of a small spring, and the lime around the spring is still dry, and then it will spread and soak around the spring. That is to say, if only lime is used, it is very difficult to seal water for gushing water;

[0081] The second layer is fine sand of the secondary bottom slag from waste incineration. The fine sand of the secondary bottom slag from waste incineration has a smaller particle size, a lower permeability coefficient, is more sheet-like, and has a larger specific surface area. However, it is not as fine as clay and does not have such a hydrophilic structure. Therefore, from the effect, if the fine sand of the secondary bottom slag from waste incineration is used, on the one hand, its water absorption and water-proof performance are better than those of ordinary fine sand. On the other hand, it is easier to form when being hammered than clay (clay is easy to become mud), and the permeability coefficient is not too small, resulting in the filler being difficult to compress and move around. In addition, the fine sand of the secondary bottom slag from waste incineration also has certain cementitious activity;

[0082] The third layer is a mixture of cement and fine sand of the secondary bottom slag from waste incineration. This layer of material is easier to form under the ramming and expansion effect and has good strength after hardening. Because of the buffering of the first two layers of materials, the cement will not be diluted too quickly by the gushing water.

[0083] It can be seen that due to the different resistances and adsorption forces of the three layers of materials inside the permeable bag, when the liquid passes through each layer, there will be sufficient time and contact area to be continuously adsorbed and retained, so that the water absorption performance of the entire permeable bag is from strong to weak, and the structural strength is from weak to strong, which not only ensures that each layer of material can fully play its water absorption performance but also ensures the continuity of the material performance.

[0084] Based on the above embodiments, the volume of quicklime is 1 / 10 to 1 / 6 of the volume of the permeable bag; the volume of the fine sand of the secondary bottom slag from waste incineration is 1 / 3 to 1 / 2 of the volume of the permeable bag; the volume of the mixture of cement and the fine sand of the secondary bottom slag from waste incineration is 1 / 3 to 1 / 2 of the volume of the permeable bag, and the mass ratio of cement to the fine sand of the secondary bottom slag from waste incineration in the mixture is 1:3 to 1:5. Specifically, when the water level of the construction stratum is relatively high, the volumes of quicklime and the fine sand of the secondary bottom slag from waste incineration take larger values, and the mass of the fine sand of the secondary bottom slag from waste incineration in the mixture of cement and the fine sand of the secondary bottom slag from waste incineration takes a larger value. The formulated high-water-stop filler 5 is conducive to quickly and effectively plugging the water gushing at the pile end, greatly improving the construction success rate in water-rich soft soil strata.

[0085] Among them, the particle size of the fine sand of the secondary bottom slag from waste incineration is 0.15 - 4.75 mm, the content of flaky particles of the fine sand of the secondary bottom slag from waste incineration is 9 - 11%, and the apparent density of the fine sand of the secondary bottom slag from waste incineration is 2400 - 2410 kg / m 3 , and the loose bulk density of the fine sand of the secondary bottom slag from waste incineration is 1175 - 1180 kg / m 3 , the porosity of the fine sand of the secondary bottom slag from waste incineration is 50 - 51%, and the crushing value is 10 - 11%.

[0086] In one embodiment, as Figure 2 shown, in order to improve the water storage and water absorption effects of the pipe pile body 1, the high-water-stop filler 5 fed in a bagged manner can freely deform in the pile end or soil under the influence of external force or space constraint. When the permeable bag filled with the high-water-stop filler 5 is put into the pipe pile body 1, the outer peripheral side of a single permeable bag abuts against the inner peripheral wall of the pipe pile body 1, that is, when in the pipe pile body 1, the cross-section of the permeable bag filled with the high-water-stop filler 5 completely covers the inner circumferential section of the precast pipe pile, or in other words, the single filling amount of the bagged feeding method is such that the diameter is the same as the inner diameter of the pipe pile when it is in a strip shape due to the constraint of the pipe wall in the pipe pile. Among them, the height of each permeable bag in the pipe pile body 1 is 20 - 30 cm. Specifically, when multiple permeable bags are filled in the pipe pile body 1, multiple permeable bags form a multi-layer water absorption structure with obvious stratification inside the pipe body. When the pressure water passes through different permeable bags, it has to repeat the three-layer water absorption process inside the permeable bag once. That is, it can avoid local saturation during the water absorption process. After the previous permeable bag reaches saturation, the next permeable bag can absorb again, avoiding the problem that once a certain area reaches saturation in a common water absorption structure, the water absorption efficiency will be greatly reduced.

[0087] In one embodiment, in order to enhance the structural strength of the subsequent water sealing plug and the reinforcement, the permeable bag is a woven mesh bag. The pore size of the woven mesh bag is smaller than the particle diameter of the high water-stop filler 5, and the pore size is such that it ensures that the filler does not leak out. On the one hand, it has good water permeability, and on the other hand, it can fully package and absorb the high water-stop filler 5. Due to the fiber structure of the woven bag, it can enhance the structural strength of the water sealing plug and prevent it from being washed away or collapsed by the pressure water. At the same time, the fiber strips formed by the rupture of the woven bag under subsequent actions can also be used as fiber reinforcement materials for the reinforcement.

[0088] S21, compact the permeable bag in the pipe pile body 1 by ramming or static pressing to form a water sealing plug on the pile plug 2. That is, during the reinforcement process of the permeable bag filled with the high water-stop filler 5, the high water-stop filler 5 is further compacted and forms a cylindrical water sealing plug with the wall of the precast pipe pile.

[0089] In one embodiment, in order to balance waterproofing and subsequent pressing treatment, the height of the water sealing plug is 5 - 30 cm. That is, the distance from the top surface of the water sealing plug to the end face of the pipe pile body 1 adjacent to the pile plug 2 is 5 - 30 cm. Through experiments, it is found that when the height of the water sealing plug is less than 5 cm, the water sealing plug is too thin, and the pressure water will wash away or collapse the water sealing plug, and the influx will form a soft mud layer at the bottom of the inner hole of the precast pipe pile, affecting subsequent ramming or extrusion. When the height of the water sealing plug is greater than 30 cm, the water sealing plug is too thick, and it is difficult to operate the subsequent pressing to penetrate the pile plug 2. That is, the force of the rammer hammering will be gradually reduced layer by layer, which is not conducive to the detachment operation of the pile plug 2.

[0090] It should be noted that during the specific implementation, the distance between the upper surface of the water sealing plug and the pile end must be kept not less than 5 cm throughout the construction process, that is, the maximum depth of the bottom end of the rammer is 5 cm higher than the hollow bottom end of the precast pipe pile. When this condition is not met, the high water-stop filler 5 must be immediately re-invested. That is, during the process of the high water-stop filler 5, the water sealing plug is formed by the bagged high water-stop filler 5, and during the subsequent filling process, the water sealing plug is formed by the subsequent filler.

[0091] In one embodiment, a compacting reinforcement method is provided. The pile end filler is reinforced by the method of ramming with a heavy hammer. The rammer for the method of ramming with a heavy hammer is preferably rammed with a low drop height, and the most suitable drop height of the rammer should be less than 2 meters. The penetration distance of the rammer is recorded every 5 rammings.

[0092] In one embodiment, another compacting reinforcement method is provided. The static press is used to clamp and push the drill rod to fill the material in a pushing manner. The pushing drill rod is a full-length hollow circular tube structure, and the bottom end has a bottom sealing plate structure that can only open outward. When filling the material into the hollow of the pushing drill rod, the bottom sealing plate structure can be opened under the action of gravity, and the filler falls into the pile end of the precast pipe pile. When the pushing drill rod is pushed downward, the bottom sealing plate structure closes. The pushing displacement needs to be recorded during the reinforcement process by the pushing method.

[0093] It should be noted that when consolidating the filling material at the pile end by the pushing method, a continuous vibration impact device should be equipped on the upper part of the pushing drill rod to generate resonance with a certain energy and frequency of the pushing drill rod. On the one hand, the resonance of the pushing drill rod can effectively promote the smooth falling of the filling material input through the hollow of the pushing drill rod into the pile end of the precast pipe pile. On the other hand, the vibration energy can be transmitted to the pile end filling material and the consolidated soil layer through the pushing drill rod, which is beneficial to further improving the consolidation effect. In particular, when the continuous vibration impact device is working, the clamping force of the static press should be appropriately reduced.

[0094] S22, Continuously feed and compact until the preset water-stop condition is met.

[0095] In specific implementation, the quicklime at the bottom of the high water-stop filling material 5 can directly absorb the water at the pile end. After the secondary bottom slag fine sand of waste incineration above the quicklime is tamped and compacted, the permeability coefficient further becomes smaller, reducing the seepage rate of the pile end water-stop filling material. At the same time, under the action of tamping and infiltration water flow, the quicklime and fine sand will be mixed to a certain extent, and their mixture can form a solidified body with a strength higher than that of the consolidated soil layer, ensuring the final strength of the high water-stop filling material 5.

[0096] In one embodiment, the preset water-stop condition is that the water content at the top of the water-stop plug is less than the preset value. The preset value can be set to 0, that is, when the water content at the top of the water-stop plug is 0, the high water-stop feeding and compaction operations are terminated, indicating that the pressure water near the insertion end of the precast pipe pile has been fully absorbed, providing guarantee for the structural strength of the pile end solidified body formed subsequently. Of course, the preset value can also be set to other possible appropriate values as long as it meets the needs of those skilled in the art.

[0097] Among them, the water content at the top of the water-stop plug can be judged directly or indirectly. For example, the indirect method can be: judging according to the dryness of the construction tool used for compaction, that is, after a compaction operation is lifted up, the part of the construction tool in contact with the water-stop plug is dry and water-free. For example, when the bottom of the rammer or the pushing drill rod is dry and water-free, it can be considered that the water content at the top of the water-stop plug is 0 and the construction of the high water-stop filling material 5 is completed. The direct method can be: using a soil sampling device to take the soil at the top of the water-stop plug and using an analysis device to judge the water content. Those skilled in the art can choose according to the actual situation.

[0098] As an example, as Figure 2 shown, a further implementable method in step S3 is provided. Step S3 specifically includes the following steps:

[0099] S30, Press and impact the water-stop plug to separate the pile plug 2 from the pipe pile body 1, that is, the pile plug 2 enters the bearing layer below the pile end under the extrusion of the upper filling material, and compacts the soil layer below the pile plug 2.

[0100] S31. Fill the pile body 1 with filler until a preset termination condition is met. Among them, in the S31 stage, that is, when filling the pile body 1 with filler, a water sealing plug is formed and maintained inside the pile body 1.

[0101] In one embodiment, step S31 specifically includes the following steps:

[0102] S310. Fill the pile body 1 with bearing layer reinforcement filler until a first preset termination condition is met. Among them, one of the first preset termination conditions is that the total volume of the bearing layer reinforcement filler reaches the designed filler volume; one of the first preset termination conditions is that the standard penetration value of the pile tip filler meets the designed standard penetration value. Specifically, during implementation, the bearing layer reinforcement filler will form a pile tip reinforcement body under the lower part of the insertion end of the pile body 1 to form a good structure.

[0103] Among them, the total filler volume t Can be estimated by the following formula:

[0104]

[0105] In the above formula, Is the maximum distance between the pile tip and the pile end of the precast pipe pile; Is the volume compression coefficient of the filler.

[0106] It should be noted that each time when filling the filler, the heavy hammer needs to be lifted out of the hollow of the precast pipe pile and then the bearing layer filler is put into the pile tip. When the filler is reinforced, the bottom end of the tamping hammer or the jacking drill rod must be kept 5 cm above the pile end to ensure the existence of the water sealing plug.

[0107] In one embodiment, in order to enhance the structural strength of the pile tip reinforcement body, a further implementation method of step S31 is provided, specifically: put an impermeable bag filled with bearing layer reinforcement filler into the pile body 1 until a first preset termination condition is met. Specifically, during implementation, the bearing layer reinforcement filler is packaged in an impermeable bag, which can prevent the bearing layer reinforcement filler from being diluted too quickly after entering the soil layer, resulting in excessive loss of cement and solving the problem of too low strength of the ramming-expanded body.

[0108] Among them, the impermeable bag is preferably packaged with a common thin film plastic bag or other impermeable materials, and those skilled in the art can choose according to actual needs.

[0109] Based on the above embodiments, the components of the bearing layer reinforcement filler include dry-hardened cement mortar and crushed stones. The mass ratio of dry-hardened cement mortar to crushed stones is 1:1 to 1:2.5, and the particle size of the crushed stones is less than or equal to 6 mm. The components of the dry-hardened cement mortar include water, cement, and secondary bottom slag from waste incineration. The mass ratio of cement to secondary bottom slag from waste incineration is 1:3 to 1:5. Water, cement, and secondary bottom slag from waste incineration are mixed to form dry-hardened cement mortar. Among them, the addition of crushed stones is to provide a transmission skeleton for the ramming energy, making it easier for the surrounding soil to be compacted and for the filler to enter the soil, thereby increasing the volume of its ramming-expanded body and further enhancing the bearing performance.

[0110] In one embodiment, due to the structural design of the precast pipe pile, a good lateral extrusion and expansion reinforcement body a can be formed. For example, the extrusion and expansion reinforcement body a is formed by cooperating the lifting rope 4 with the pile plug 2 having an extrusion guiding section, the extrusion and expansion reinforcement body a is formed by cooperating the lifting rope 4 with the opening and closing type pile plug, and the extrusion and expansion reinforcement body a is formed by the formation of the bladder cap 25, and the soil is made to form a compacted soil body b and an affected soil body c.

[0111] S311, put the core filling material into the pipe pile body 1 until the second preset termination condition is met, and obtain the pile foundation structure 6. Among them, the second preset termination condition is that the core filling height should be not less than 2 m above the pile end. Specifically, during implementation, after the bearing layer reinforcement filler forms a reinforcement body, the core filling material fills the remaining hollow of the pipe pile body 1 to ensure the structural strength of the entire pile foundation structure 6.

[0112] In one embodiment, the core filling material is concrete with a strength above C30.

[0113] In one embodiment, after core filling, a heavy hammer is used to ram or a drill rod is pushed to extrude the core filling concrete to improve the density of the core filling section concrete and enhance the connection strength between the core filling section and the filler of the bearing layer to be reinforced at the pile end.

[0114] In one embodiment, a method for pressing in the filler is provided, which uses a reverse rotation of a screw drill for pressing in; when the screw drill rotates in reverse for pressing in, a continuous feeding filler method is adopted, which is beneficial for the filler to continuously squeeze towards the pile end through the channel formed by the screw drill rod and the precast pipe pile.

[0115] The embodiment of the present invention provides a precast pipe pile, which is applied in the above precast pipe pile construction method to solve the technical problem of poor water sealing ability during the early stage of filler reinforcement in the prior art.

[0116] Please refer to Figures 3 to 11 , a precast pipe pile provided in this embodiment includes:

[0117] The pipe pile body 1, and the pipe pile body 1 is hollow;

[0118] The pile plug 2 is inserted into the end of the pipe pile body 1; the pile plug 2 can be detached from the pipe pile body 1 after being subjected to a preset pressure;

[0119] The seal 3 can be elastically clamped between the pipe pile body 1 and the pile plug 2.

[0120] In this embodiment, the pile plug 2 is inserted into the end of the pipe pile body 1. When the pile plug 2 is inserted into the pipe pile body 1, the seal 3 will be elastically clamped between the pipe pile body 1 and the pile plug 2, and the seal 3 between the pile plug 2 and the pipe pile body 1 can keep the end of the precast pipe pile with the pile plug 2 sealed; when the pile plug 2 is subjected to a preset pressure, the pile plug 2 will be detached from the pipe pile body 1.

[0121] Based on the above embodiment, in a specific construction process, the following steps are included:

[0122] S1, insert the pile plug 2 into the pipe pile body 1 to form an assembled precast pipe pile, and press the assembled precast pipe pile into the soil at a preset depth;

[0123] S2, put the permeable bag filled with the high water-stop filler 5 into the pipe pile body 1, and compact the permeable bag in the pipe pile body 1 to form a water-stop plug on the pile plug 2, and continuously feed and compact until the preset water-stop condition is met. Among them, the pile plug 2 remains inserted on the pipe pile body 1;

[0124] S3, press the water-stop plug so that the pile plug 2 is detached from the pipe pile body 1, and put filler into the pipe pile body 1 until the preset termination condition is met;

[0125] It can be seen from the above process that the pile plug 2 remains inserted on the pipe pile body 1, and the seal 3 is elastically clamped between the two, so the seal can be maintained between the pile plug 2 and the pipe pile body 1, and it is difficult for pressure water and soil to enter between the pile plug 2 and the pipe pile body 1, avoiding the phenomenon of piping; and because of the permeable bag provided with the high water-stop filler 5, it can absorb water and block the entry of soft mud, avoiding the problem of the appearance of a soft mud layer inside the pipe pile body 1.

[0126] As an example, as Figure 3 、 Figure 10 and Figure 11 shown, the realizable structure of the seal 3 is further provided. The seal 3 can be an O-ring. When the seal 3 is an O-ring, a groove for accommodating the O-ring can be designed on the inner wall of the precast pipe pile or the inner wall of the pile plug 2. After the O-ring is placed in the groove, the precast pipe pile and the pile plug 2 can clamp the O-ring to make it elastically deformed to play a sealing role; the seal 3 can also be a sealing cap. The sealing cap covers the outside of the pile plug 2, and then the structure formed by the sealing cap and the pile plug 2 is inserted into the precast pipe pile together. The sealing cap is elastically deformed under the clamping of the pile plug 2 and the precast pipe pile to play a sealing role.

[0127] As an example, as Figure 3 and Figure 11 shown, a realizable structure of the precast pipe pile is further provided. The precast pipe pile includes a pile plug 2 and a pipe pile body 1. The connection method in which the pile plug 2 can be separated from the pipe pile body 1 under pressure can be that the pile plug 2 is connected to the pipe pile body 1 by frictional cooperation, that is, the pile plug 2 is embedded in the hollow position of the pipe pile body 1 by friction. When the pressure on the pile plug 2 is greater than the friction force it receives, the pile plug 2 will be disengaged from the pipe pile body 1; it can also be that the pile plug 2 and the pipe pile body 1 are connected by spot welding with a preset connection strength. When the pressure on the pile plug 2 is greater than the spot welding connection force it receives, the pile plug 2 will be disengaged from the pipe pile body 1. For other structures that can achieve separation under pressure, those skilled in the art can also make selections, and no more restrictions are imposed here.

[0128] As an example, to solve the technical problem of insufficient lateral expansion effect of the expanded reinforcement body a at the pile end, as Figure 3 shown, the precast pipe pile further includes a plurality of lifting ropes 4; one end of each lifting rope 4 is fixedly connected to the pipe pile body 1 through a lifting ring, and the other end of each lifting rope 4 is fixedly connected to the pile plug 2 through a lifting ring. The plurality of lifting ropes 4 are arranged around the center of the pile plug 2.

[0129] Specifically, when implementing step S3, when the pile plug 2 is separated from the pipe pile body 1, the pile plug 2 will be suspended below the insertion end of the pipe pile body 1; when filling materials are put into the pipe pile body 1, the pile plug 2 will move downward and compress the soil layer below the pile plug 2. When the filling materials filled at the bottom of the precast pipe pile reach a certain volume, the soil layer of the bearing stratum below the pile plug 2 is fully compressed, and the support for the pile plug 2 no longer allows it to move downward; if the strength of the soil body of the reinforced bearing stratum is low, the pile plug 2 will be restricted from continuing to move downward after reaching the maximum length of the lifting rope. The subsequent filling materials form a nearly spherical filling-expanded reinforcement body a with a lateral diameter larger than the diameter of the precast pipe pile at the lower part of the precast pipe pile. At the outer edge of the expanded reinforcement body a, the soil body of the bearing stratum forms a densified soil body b and an affected soil body c with a larger volume and a compression modulus higher than that of the original bearing stratum soil body under the action of stress waves or extrusion.

[0130] As can be seen from the above, the existence of the lifting ropes 4 can prevent the pile plug 2 from moving downward without limit. In the scenario of water-rich soft soil, the lifting ropes 4 cooperate with the pile plug 2 to enable the filling materials to form an expanded reinforcement body a, a densified soil body b and an affected soil body c at the lower part of the precast pipe pile, and the strength of the entire pile foundation structure 6 is ensured.

[0131] In one embodiment, the suspension rope 4 is a corrosion-resistant and high-strength steel wire rope, and the material can be selected according to the characteristics of the bearing layer. The length of the suspension rope 4 can control the maximum distance S between the pile plug 2 and the end of the precast pipe pile, which can be selected according to the properties of the bearing layer soil. The following provides a method: for saturated silt and clay bearing layers with standard penetration values Nk of 5 < Nk ≤ 10, 10 < Nk ≤ 15, and Nk > 15 respectively, the values of the maximum distance S are 2.5D to 3D, 2D to 2.5D, and 1.5D to 2D respectively, where D is the diameter of the precast pipe pile.

[0132] Based on the above embodiment of the suspension rope 4, in one embodiment, as Figure 3 shown, in order to improve the lateral expansion effect, a realizable structure of the pile plug 2 is further provided. The pile plug 2 has an expansion guiding section. Along the direction from the pipe pile body 1 to the pile plug 2, the pile diameter of the expansion guiding section gradually increases, that is, the surface axis formed by the expansion guiding section forms a certain angle with the axis of the pipe pile body 1. Specifically, when step S3 is implemented, after the pile plug 2 is separated from the pipe pile body 1, filler is put into the pipe pile body 1. Due to the existence of the suspension rope 4, the expansion guiding section of the pile plug 2 can guide the filler to move to both sides of the pile plug 2, which can greatly promote the filling of the filler to both sides of the pile end. As the filler is added, the filler continuously squeezes into both sides under the guidance of the conical expansion guiding section, strengthening the soil on the pile side and forming an expansion reinforcement body a whose volume is several times that of the diameter of the precast pipe pile, significantly improving the bearing capacity of the end of the precast pipe pile in the water-rich soft soil layer.

[0133] Further, in one embodiment, as Figure 3 shown, in order to better improve the effect of the lateral expansion effect, a specific implementation structure of the pile plug 2 is provided. Along the direction from the pipe pile body 1 to the pile plug 2, the pile plug 2 sequentially includes an upper expansion guiding section 20, a stepped section 21, a lower expansion guiding section 22, and a constant diameter section. The maximum pile diameter of the upper expansion guiding section 20 is less than or equal to the minimum pile diameter of the lower expansion guiding section 22, and the pile diameter of the upper expansion guiding section 20 is slightly smaller than the inner diameter of the hollow of the pipe pile body 1. The stepped section 21 includes a narrow-diameter stepped section and a wide-diameter stepped section. The narrow-diameter stepped section and the wide-diameter stepped section form a step that is clamped to the bottom of the pipe pile body 1. The narrow-diameter stepped section is inserted into the pipe pile body 1, and the wide-diameter stepped section abuts against the bottom of the pipe pile body 1. The stepped section 21 is used to clamp the pile plug 2 on the pipe pile body 1, that is, to embed the upper expansion guiding section 20 into the pipe pile body 1 and clamp the wide-diameter stepped section outside the pipe pile body 1. Specifically, when step S3 is implemented, after the pile plug 2 is separated from the pipe pile body 1, the upper expansion guiding section 20 is located at the top of the pile plug 2, and the filler just coming from the precast pipe pile can be initially guided to both sides, avoiding the accumulation of materials at the top of the pile plug 2. The lower expansion guiding section 22 can secondarily guide the moving direction of the filler, making the lateral expansion area of the expansion reinforcement body a larger.

[0134] In one embodiment, asFigure 10 As shown, the pile plug 2 can adopt a sealing ring or a sealing cap, as long as the sealing ability of the pile plug 2 and the pipe pile body 1 is ensured when the pile plug 2 is inserted into the pipe pile body 1.

[0135] Further, in an embodiment, as Figures 4 to 9 shown, in order to better improve the effect of the lateral extrusion and expansion effect, a specific implementation structure of the pile plug 2 is provided. The pile plug 2 includes a connecting seat 23 and at least three pile petals 24. The plurality of pile petals 24 are arranged on the circumferential side of the connecting seat 23. The pile petals 24 are hinged to the connecting seat 23. The plurality of pile petals 24 can be turned over to surround the connecting seat 23 or can be turned over and unfolded to form an opening and closing type pile plug. Specifically, when the step S3 is implemented, after the pile plug 2 is separated from the pipe pile body 1, the pile plug 2 will be turned from the original state of surrounding the connecting seat 23 to the unfolded state under the upper pushing action, forming a structure like a petal. The outer contour diameter of the unfolded pile plug 2 is much larger than the diameter of the precast pipe pile, which can greatly improve the lateral filling guiding ability of the pile plug 2 and form a nearly spherical filling extrusion body with a diameter several times that of the precast pipe pile at the pile end of the precast pipe pile.

[0136] It should be noted that different positions of the pile petals 24 and the connecting seat 23 will divide the pile plug 2 into two types: an upper hinged opening and closing type pile plug (as Figures 4 to 7 shown) and a lower hinged opening and closing type pile plug (as Figures 8 to 9 shown). The upper hinged split pile plug is provided with a hinged arm at the top of the pile plug 2, and a pin hole is arranged inside the hinged arm. A lifting ring is arranged on the outer wall of the upper section of the upper hinged split pile plug. The upper hinged split pile plug is connected to the double cross hinge seat through the hinged arm to form an upper hinged opening and closing type pile plug. The lower hinged split pile plug is provided with a hinged arm at the bottom of the pile plug 2, and a pin hole is arranged inside the hinged arm. The lower hinged split pile plug is connected to the double cross hinge seat through the hinged arm to form a lower hinged opening and closing type pile plug.

[0137] In an embodiment, as Figures 4 to 7 shown, the pile plug 2 is an upper hinged opening and closing type pile plug. A lifting rope 4 is used to connect the lifting ring of the pile plug 2 of the upper hinged opening and closing type pile plug and the precast pipe pile. A fixing step with an outer diameter slightly smaller than the inner diameter of the precast pipe pile is arranged at the upper end of the upper hinged split pile plug, which is used for the opening and closing type pile plug to be embedded into the inner hole of the precast pipe pile to realize the installation of the opening and closing type pile plug at the pile end of the precast pipe pile. Specifically, when the step S3 is implemented, after the pile plug 2 is separated from the pipe pile body 1, due to the limiting effect of the lifting rope 4, under the upper pushing action and the limiting action of the lifting rope 4, the lower end of the split pile plug will open outwards, and finally a petal-shaped pile plug 2 with an outer diameter larger than several times that of the precast pipe pile will be formed at a certain distance from the bottom of the precast pipe pile.

[0138] In an embodiment, as Figures 8 to 9As shown, the pile plug 2 is a lower-hinged opening and closing type pile plug. The lower-hinged opening and closing type pile plug does not need to be connected to the pipe pile body 1 through the lifting rope 4. An embedding step with an outer diameter slightly smaller than the inner diameter of the precast pipe pile is provided at the upper end of the lower-hinged split pile plug, which is used for the opening and closing type pile plug to be embedded in the inner hole of the precast pipe pile to realize the installation of the opening and closing type pile plug at the pile end of the precast pipe pile. Specifically, when the step S3 is implemented, after the pile plug 2 is separated from the pipe pile body 1, the pile plug 2 is completely separated from the pipe pile body 1. Due to the upper pushing effect, the split pile plug opens outward from the upper end and finally forms a petal-like structure.

[0139] It should be noted that the lower-hinged opening and closing type pile plug is not restricted by the lifting rope 4, and its pressing depth is mainly determined by the properties of the soil layer at the pile bottom, which can effectively make up for the defect of insufficient reinforcement of the bearing layer directly below the upper-hinged opening and closing type pile plug caused by design. Of course, those skilled in the art can make corresponding choices. The lower-hinged opening and closing type pile plug can be connected with the lifting rope 4 and retain the defect of insufficient reinforcement of the bearing layer directly below the upper-hinged opening and closing type pile plug, and those skilled in the art can choose according to actual needs.

[0140] In an embodiment, along the direction from the pipe pile body 1 to the pile plug 2 on the pile lobe 24, the pile lobe 24 sequentially includes a narrow-diameter pile section, an extrusion and expansion guiding section, and a normal-diameter pile section. Specifically, when the step S3 is implemented, the extrusion and expansion guiding section can greatly increase the overall volume of the extrusion and expansion reinforcement body a in cooperation with the petal-like structure.

[0141] In an embodiment, the pile plug 2 using the pile lobe 24 can select a sealing cap as the seal 3. That is, when the pile plug 2 is inserted into the pipe pile body 1, the sealing cap is covered on the pile plug 2, and the brim of the sealing cap is elastically clamped between the pile plug 2 and the pipe pile body 1.

[0142] As an example, to solve the technical problem of insufficient lateral extrusion and expansion effect of the pile end reinforcement body, as Figure 11 shown, the precast pipe pile further includes a bladder cap 25; the bladder cap 25 includes a cap body and a brim; a circle of brim is connected to the periphery of the cap body; the cap body covers above the pile plug 2, and the brim is fixedly connected to the pipe pile body 1. Among them, the pile plug 2 and the pipe pile body 1 are connected by spot welding at 2-3 places, and the welding strength is such that the bottom-sealing pile plug 2 will not fall off under the action of gravity.

[0143] Specifically, when the step S2 is implemented, the bagged high-water-stop filler 5 will form a water-sealing plug on the bladder cap 25. Then, when the step S3 is implemented, the bladder cap 25 will squeeze the pile plug 2 to separate from the pipe pile body 1 and form a spherical extrusion and expansion reinforcement body a, a compacted soil body b, and an affected soil body c below the pipe pile body 1.

[0144] As can be seen from the above, the bladder cap 25 can form a spherical expanded and compacted solid a under the precast pile body 1 without the suspension rope 4, which can solve the problem of insufficient lateral expansion effect of the pile tip compacted solid. Compared with the suspension rope 4 scheme, the proposed bladder cap 25 scheme can effectively solve the construction of the pile tip filling reinforcement of precast piles in high water pressure and deep silt distribution bearing layers. On the one hand, it ensures the effectiveness and continuity of water sealing during the reinforcement stage; on the other hand, the restriction of the bladder can well form a near-spherical filling compacted solid.

[0145] It should be noted that after the bladder cap 25 is adopted, the high water-stop filler 5 added in step S2 can be replaced by a high-strength concrete filler to ensure the strength of the pile tip compacted solid, and those skilled in the art can choose according to actual needs.

[0146] In addition, when using the bladder method for reinforcement, it is advisable to use a non-tamping method to reinforce the filler; when the tamping method must be used, the filler should be filled first and then tamped with low energy to avoid the rammer directly hitting the bladder.

[0147] In an embodiment, as Figure 11 shown, the open end of the bladder cap 25 is provided with a bladder cap 25 annular fixing ring, and circular holes corresponding to the threaded holes of the precast pile end plate are evenly distributed in the bladder cap 25 annular fixing ring. The bladder annular fixing ring of the bladder is fixed on the precast pile end plate through fastening screws. After the bladder is folded, it is placed in the hollow of the precast pile bottom. A pile plug 2 is installed below the bladder cap 25. There is a gap between the part where the pile plug 2 and the bladder annular fixing ring overlap along the radial direction. A sealing ring is arranged in the gap between the pile plug 2 and the precast pile, and the sealing ring is elastically clamped by the pile plug 2 and the precast pile.

[0148] In an embodiment, the bladder cap 25 is a spherical open bag structure after being unfolded. The bladder is composed of a membranous organic material or inorganic material and can be made of a high-strength material with internal reinforcement in the bladder cap 25 to make it have the characteristic of being easily deformed.

[0149] Summarizing the above precast piles, the similarities of the above precast piles are as follows: first, both the pile plug 2 and the pile body 1 are provided with a sealing member 3, which can play a role in sealing and waterproofing; second, their purposes are all to form an expanded and compacted solid a with a large enough lateral volume under the pile body 1; the differences are that the structures for specifically forming the expanded and compacted solid a are different. At least there are forming the expanded and compacted solid a by cooperating the suspension rope 4 with the pile plug 2 having an expansion guiding section, forming the expanded and compacted solid a by cooperating the suspension rope 4 with the opening and closing type pile plug, and forming the expanded and compacted solid a by the bladder cap 25. Thus, it can be seen that there are many categories of precast piles provided by this scheme that can execute the precast pile construction method, and the content is very detailed. Those skilled in the art can choose according to actual needs.

[0150] The embodiment of the present invention provides a pile foundation structure 6, as Figure 12and Figure 13 As shown, the precast pipe pile is constructed according to the above-mentioned precast pipe pile construction method to obtain the pile foundation structure 6. Among them, as Figure 12 shown, the pile foundation structure 6 is a pile foundation structure 6 including a suspension rope, and as Figure 13 shown, the pile foundation structure 6 is a pile foundation structure 6 including a bladder cap 25.

[0151] The formed pile foundation structure 6 has the following advantages: on the one hand, during the early filling process, through the cooperation of the bagged high-water-stop filler 5, the water-stop plug and the seal 3, it can effectively prevent water or soft mud layers from entering the precast pipe pile, ensure the water-stop ability during the pile bottom reinforcement process, and improve the quality of the consolidated body; on the other hand, due to the designed structure of the precast pipe pile, a laterally expanded consolidated body a with a large enough volume can be formed under the pipe pile body 1, ensuring sufficient lateral expansion effect and enhancing the bearing capacity of the pile end reinforced pile of the precast pipe pile with a small or medium diameter.

[0152] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0153] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

Claims

1. A prefabricated pipe pile construction method, characterized in that: The following steps are involved: Inserting a pile plug into the end of a hollow pipe pile body to form a prefabricated pipe pile, and pressing the prefabricated pipe pile into the soil at a preset depth; Putting a water-permeable bag filled with high water-stopping filler into the pipe pile body, and compacting the water-permeable bag in the pipe pile body to form a water-sealing plug on the pile plug, and continuing to put in materials and compact until the preset water-stopping conditions are met, wherein the pile plug remains inserted into the pipe pile body; Pressing the water sealing plug to separate the pile plug from the pile body, and injecting filler into the pile body until a preset termination condition is met; The components of the high water-stop filler include dry quicklime, dry waste incineration secondary bottom slag fine sand, and a mixture of dry cement and waste incineration secondary bottom slag fine sand; The method of placing high water-stop filler into a permeable bag comprises the following steps: First, the quicklime is filled into the water permeable bag; Then, the waste incineration secondary bottom ash fine sand is filled into the water permeable bag; Finally, the mixture of the cement and the fine sand from the secondary bottom ash of waste incineration is filled into the water-permeable bag; When the water-permeable bag filled with the high water-stop filler is put into the pipe pile body, the outer peripheral side surface of a single water-permeable bag abuts against the inner peripheral wall of the pipe pile body.

2. The prefabricated pipe pile construction method according to claim 1, characterized in that: The volume of the quicklime is 1 / 10 to 1 / 6 of the volume of the permeable bag; The volume of the fine sand from the secondary bottom ash of garbage incineration is 1 / 3 to 1 / 2 of the volume of the permeable bag; The volume of the mixture of the cement and the fine sand from the secondary bottom ash of waste incineration is 1 / 3 to 1 / 2 of the volume of the permeable bag, and the mass ratio of the cement to the fine sand from the secondary bottom ash of waste incineration in the mixture is 1:3 to 1:

5.

3. The prefabricated pipe pile construction method according to claim 1, characterized in that: The water-permeable bag is a woven mesh bag.

4. The prefabricated pipe pile construction method according to claim 1, characterized in that: The height of the water sealing plug is 5cm-30cm.

5. The prefabricated pipe pile construction method according to claim 1, characterized in that: The preset water-stopping condition is that the water content at the top of the water-sealing plug is less than a preset value.

6. The prefabricated pipe pile construction method according to claim 1, characterized in that: Filling is added to the pile body until a preset termination condition is met. Specifically, in this step: Adding bearing layer reinforcement filler into the pipe pile body until a first preset termination condition is met; A core filling material is added into the pipe pile body until a second preset termination condition is met.

7. The prefabricated pipe pile construction method according to claim 6, characterized in that: In the step of adding a bearing layer reinforcement filler into the pipe pile body until the first preset termination condition is met, the specific steps are as follows: A watertight bag filled with a bearing layer reinforcement filler is put into the pipe pile body until the first preset termination condition is met.

8. The prefabricated pipe pile construction method according to claim 7, characterized in that: The components of the bearing layer reinforcement filler include dry hard cement mortar and crushed stone, the mass ratio of the dry hard cement mortar to the crushed stone is 1:1-1:2.5, and the particle size of the crushed stone is less than or equal to 6 mm; The components of the dry hard cement mortar include water, cement and secondary bottom ash from waste incineration, and the mass ratio of the cement to the secondary bottom ash from waste incineration is 1:3-1:

5.

9. A pile foundation structure, characterized in that: The prefabricated pipe pile is constructed by using the prefabricated pipe pile construction method according to any one of claims 1 to 8, wherein the prefabricated pipe pile comprises a hollow pipe pile body, a pile plug and a sealing member; The pile plug is inserted into the end of the pipe pile body; the pile plug can be separated from the pipe pile body after being subjected to a preset pressure; The sealing member is elastically clamped between the pipe pile body and the pile plug.

10. The pile foundation structure according to claim 9, characterized in that: The prefabricated pipe pile also includes a plurality of hanging ropes; One end of the lifting rope is connected and fixed to the pipe pile body, and the other end of the lifting rope is connected and fixed to the pile plug.

11. The pile foundation structure according to claim 10, characterized in that: The pile plug has an extrusion and expansion guide section, and the pile diameter of the extrusion and expansion guide section gradually increases along the direction from the pipe pile body to the pile plug.

12. The pile foundation structure according to claim 11, characterized in that: Along the direction from the pipe pile body to the pile plug, the pile plug comprises an upper extrusion and expansion guide section, a platform section and a lower extrusion and expansion guide section in sequence; The maximum pile diameter of the upper extrusion and expansion guide section is less than or equal to the minimum pile diameter of the lower extrusion and expansion guide section; The stage is used to clamp the pile plug onto the pipe pile body.

13. The pile foundation structure according to claim 9 or 10, characterized in that: The pile plug comprises a connection seat and a plurality of pile petals, wherein the plurality of pile petals are arranged on the peripheral side of the connection seat, the pile petals are hinged to the connection seat, and the plurality of pile petals can be turned over to surround the connection seat or can be turned over to unfold.

14. The pile foundation structure according to claim 9, characterized in that: The prefabricated pipe pile also includes a bag cap; The pouch cap comprises a cap body and a brim; The circumference of the cap body is connected with a circle of the cap brim; The cap body is arranged above the pile plug, and the cap brim is connected and fixed to the pipe pile body.

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