A construction method for a special-shaped prefabricated pile zipper support structure

Abstract

This invention discloses a zipper-type support structure for irregularly shaped precast piles and its construction method. The irregularly shaped precast piles include irregularly shaped pile end plates and irregularly shaped pile bodies. The pile body is made of concrete and prestressed, with a reinforcing cage inside, and the pile web is a hollow circle. The irregularly shaped precast piles are irregularly short T-shaped. The construction method involves symmetrically constructing the irregularly shaped precast piles on-site in a staggered manner. Two staggered irregularly shaped precast piles are tightly interlocked to form a chain-type support structure. After the interlocking construction of the irregularly shaped precast piles is completed, a small-diameter high-pressure jet grouting mixing pile is constructed at the joint of the two parallel irregularly shaped precast piles to form a high-pressure jet grouting waterstop to seal the gap formed by the parallel irregularly shaped precast piles. A concrete cap beam is installed on top of the irregularly shaped precast piles. This invention is particularly suitable for construction environments with limited space, saves on concrete and cement usage for the waterstop mixing piles, and enhances the integrity and resistance to lateral deformation of the foundation pit support structure, resulting in significant economic and environmental benefits.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a special-shaped prefabricated pile zipper-type supporting structure and a construction method thereof. Background Art

[0002] With the increasing requirements for environmental protection in my country, the traditional foundation pit support method of using mud wall bored piles has been gradually restricted. However, with the vigorous development of construction in my country, the development and utilization of underground space is becoming increasingly prosperous. There is bound to be a contradiction between the two. In addition, with the continuous rise in land prices, the planned basement exterior walls are getting closer and closer to the red line of the building land, and the scope that can be used for foundation pit support is also getting smaller and smaller. For conventional foundation pit support methods, the width of the supporting piles and waterstop piles needs to be at least 3.0m, and the project site cannot meet the land requirements of the supporting piles and waterstop piles.

[0003] There is a Chinese utility model patent (application number 201120407042.9) involving a prestressed reinforced concrete special-shaped precast pile. The pile shape of the concrete precast pile is special-shaped, a center hole is opened in the center of the concrete precast pile, and steel plate pile caps are provided at both ends of the concrete precast pile. The advantage is that the special-shaped precast pile increases the surface area, greatly improving the vertical friction and vertical bearing capacity; at the same time, the cross section is increased, and the bending resistance of the pile body is correspondingly increased, that is, the bearing capacity of the entire pile body is effectively improved. However, there are still the following shortcomings: (1) only the compressive resistance of the prestressed reinforced concrete special-shaped precast pile under vertical bearing is improved, while the horizontal shear resistance of the foundation pit engineering support pile under horizontal bearing is not enhanced; (2) It is impossible to form a continuous water-stopping system, and water leakage will occur when used in foundation pit support engineering, endangering the safety of the foundation pit.

[0004] Based on the above analysis, a supporting structure and construction method that can both retain soil and stop water and occupy a small area is urgently needed in foundation pit projects. Summary of the invention

[0005] In order to solve the deficiencies in the above-mentioned prior art, the present invention provides a special-shaped prefabricated pile zipper support structure and construction method which has greater bending and horizontal shear resistance and water-stopping ability, is convenient and fast to construct, has low engineering cost and small environmental impact, and especially occupies a small area.

[0006] The purpose of the present invention is achieved like this:

[0007] A zipper-type support structure for special-shaped prefabricated piles, wherein the special-shaped prefabricated piles 1 include special-shaped pile end plates 4 and special-shaped prefabricated pile bodies; the special-shaped prefabricated pile bodies are made of concrete material and prestressed, a steel cage is arranged inside the special-shaped prefabricated pile bodies, and the pile belly of the special-shaped prefabricated piles is in a hollow circular shape; the special-shaped prefabricated piles 1 are irregular short T-shaped;

[0008] The special-shaped pile end plate 4 is made of a steel plate with a thickness of not less than 20 mm and a steel grade not less than Q235B. The cross-sectional shape of the special-shaped pile end plate 4 is the same as the cross-sectional shape of the special-shaped prefabricated pile 1;

[0009] The concrete strength grade of the special-shaped prefabricated pile body is C60-C80;

[0010] The reinforcement ratio of the steel cage arranged inside the special-shaped prefabricated pile body is not less than 0.2%, and the longitudinal reinforcement of the steel cage is made of prestressed concrete steel rod 5, and the stirrups are made of spiral high-strength steel bars;

[0011] The special-shaped prefabricated pile 1 is prestressed according to the engineering requirements, wherein the prestress is applied before the concrete of the pile body is poured;

[0012] The belly of the special-shaped prefabricated pile is a hollow circle 2, wherein the diameter of the hollow circle 2 is 0.25 to 0.3 times the long side of the T-shaped special-shaped prefabricated pile;

[0013] The construction method of the special-shaped prefabricated pile zipper support structure comprises the following main construction steps:

[0014] Step 1: After the special-shaped prefabricated piles are processed and manufactured in the factory, they are transported to the project site, the pile driving machinery is in place, and the pile driving machinery and equipment are debugged;

[0015] Step 2: After the pile driver is in place and debugged, the special-shaped prefabricated piles are slowly pressed down in sequence and symmetrically on both sides to form a zipper-type support structure, and the bidirectional vertical deviation is continuously corrected;

[0016] Step 3: When using multi-section special-shaped prefabricated piles, connect the piles on site;

[0017] Step 4: construct a small-diameter high-pressure jet-jet mixing pile 3 at the gap between two parallel special-shaped prefabricated piles;

[0018] Step 5: Arrange the concrete crown beam 6 on the top of the special-shaped precast pile and the first concrete inner support 7;

[0019] Step 6: excavate earth to the second support elevation, and set up concrete purlin 8 and second concrete inner support 9;

[0020] Step 7: Carry out subsequent foundation pit construction work. The subsequent construction of the foundation pit is the same as the ordinary foundation pit construction method;

[0021] The special-shaped prefabricated pile construction method comprises the following steps: staggering and symmetrically constructing the special-shaped prefabricated piles on site; the two staggered special-shaped prefabricated piles are tightly buckled to form a chain-type support structure;

[0022] After the special-shaped prefabricated pile buckle construction is completed, a small-diameter high-pressure rotary grouting and mixing pile 3 is constructed at the joint of two parallel special-shaped prefabricated piles to form a high-pressure rotary grouting and mixing water-stop body to block the gap formed by the parallel special-shaped prefabricated piles;

[0023] A concrete cap beam is arranged on the top of the special-shaped prefabricated pile.

[0024] Positive and beneficial effects: The present invention has the following effects: 1. It reduces the scope of land used for foundation pit support structures and greatly develops the utilization rate of land; there is no mud discharge and dust generation during the construction process, which meets the requirements of green and environmentally friendly buildings; 2. The foundation pit support project is low in cost, the construction speed is fast, the total construction period is greatly shortened, and the benefit of rapid turnover of less funds is achieved; 3. The construction method is simple and has the conditions for wide promotion and application; 4. The special-shaped prefabricated piles are hollow sections, saving concrete; 5. After the parallel pile driving construction, small-diameter high-pressure rotary jet mixing piles are used to stop water in the formed gaps, and there is no need to set up a row of water-stopping piles, saving building materials; 6. The special-shaped prefabricated piles are produced in factories, the quality is controllable, and they can be mass-produced, and prefabricated piles can be applied with prestress, which further improves the stiffness of the pile body, gives full play to the material properties, and saves materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a plan view schematic diagram of the present invention;

[0026] Figure 2 It is a three-dimensional schematic diagram of the present invention;

[0027] Figure 3 It is a three-dimensional schematic diagram of special-shaped prefabricated supporting piles;

[0028] Figure 4 This is a schematic diagram of the end plate of the special-shaped prefabricated support pile;

[0029] Figure 5 It is a cross-sectional schematic diagram of the foundation pit support structure of the present invention;

[0030] The figure shows: special-shaped prefabricated supporting piles 1, center circle of special-shaped prefabricated supporting piles 2, small-diameter high-pressure rotary jet mixing piles 3, pile end plates 4, steel rods for prestressed concrete 5, pile top crown beams 6, first concrete inner supports 7, concrete surrounding purlins 8, and second concrete inner supports 9. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0032] like Figure 1-5As shown, a zipper-type support structure of a special-shaped prefabricated pile, wherein the special-shaped prefabricated pile 1 comprises a special-shaped pile end plate 4 and a special-shaped prefabricated pile body; the special-shaped prefabricated pile body is made of concrete material and prestressed, a steel cage is arranged inside the special-shaped prefabricated pile body, and the belly of the special-shaped prefabricated pile is a hollow circle; the special-shaped prefabricated pile 1 is an irregular short T-shape;

[0033] The special-shaped pile end plate 4 is made of a steel plate with a thickness of not less than 20 mm and a steel grade not less than Q235B. The cross-sectional shape of the special-shaped pile end plate 4 is the same as the cross-sectional shape of the special-shaped prefabricated pile 1;

[0034] The concrete strength grade of the special-shaped prefabricated pile body is C60-C80;

[0035] The reinforcement ratio of the steel cage arranged inside the special-shaped prefabricated pile body is not less than 0.2%, and the longitudinal reinforcement of the steel cage is made of prestressed concrete steel rod 5, and the stirrups are made of spiral high-strength steel bars;

[0036] The special-shaped prefabricated pile 1 is prestressed according to the engineering requirements, wherein the prestress is applied before the concrete of the pile body is poured;

[0037] The belly of the special-shaped prefabricated pile is a hollow circle 2, wherein the diameter of the hollow circle 2 is 0.25 to 0.3 times the long side of the T-shaped special-shaped prefabricated pile;

[0038] The construction method of the special-shaped prefabricated pile zipper support structure comprises the following main construction steps:

[0039] Step 1: After the special-shaped prefabricated piles are processed and manufactured in the factory, they are transported to the project site, the pile driving machinery is in place, and the pile driving machinery and equipment are debugged;

[0040] Step 2: After the pile driver is in place and debugged, the special-shaped prefabricated piles are slowly pressed down in sequence and symmetrically on both sides to form a zipper-type support structure, and the bidirectional vertical deviation is continuously corrected;

[0041] Step 3: When using multi-section special-shaped prefabricated piles, connect the piles on site;

[0042] Step 4: construct a small-diameter high-pressure rotary grouting pile 3 at the gap between two parallel special-shaped prefabricated piles;

[0043] Step 5: Arrange the concrete crown beam 6 on the top of the special-shaped precast pile and the first concrete inner support 7;

[0044] Step 6: excavate earth to the second support elevation, and set up concrete purlin 8 and second concrete inner support 9;

[0045] Step 7: Carry out subsequent foundation pit construction work. The subsequent construction of the foundation pit is the same as the ordinary foundation pit construction method;

[0046] The special-shaped prefabricated pile construction method comprises the following steps: staggering and symmetrically constructing the special-shaped prefabricated piles on site; the two staggered special-shaped prefabricated piles are tightly buckled to form a chain-type support structure;

[0047] After the special-shaped prefabricated pile buckle construction is completed, a small-diameter high-pressure rotary grouting and mixing pile 3 is constructed at the joint of two parallel special-shaped prefabricated piles to form a high-pressure rotary grouting and mixing water-stop body to block the gap formed by the parallel special-shaped prefabricated piles;

[0048] A concrete cap beam is arranged on the top of the special-shaped prefabricated pile.

[0049] Example 1

[0050] like Figures 1 to 5 As shown, the zipper-type support structure of special-shaped prefabricated piles of the present invention is mainly composed of special-shaped prefabricated support piles 1 that are staggered and symmetrically constructed in parallel; after two rows of special-shaped prefabricated support piles constructed in parallel are staggered and symmetrically constructed, a zipper-type row of piles support structure is formed. At the gap formed by the two special-shaped prefabricated piles constructed in parallel, high-pressure rotary jet mixing piles 3 are constructed to block the gap, and then a concrete crown beam 5 is set to form the entire support system.

[0051] In this embodiment, the special-shaped precast pile 1 is a concrete precast pile, and the pile body concrete strength grade is C60-C80, the long side length is 1200mm, the short side length is 300mm, and the short T height is 550mm. The pile body of the special-shaped precast pile is hollow, wherein the hollow is a hollow circle 2 with a diameter of 300mm; the prestressed concrete steel rod 5 set in the pile body of the special-shaped precast supporting pile 1 adopts a model with a tensile strength of not less than 1420MPa and a diameter of 12.6mm.

[0052] If the construction process requires pile connection, two special-shaped prefabricated supporting piles are welded together through the pile end steel end plate 4, and then the piles are sunk as a whole. The steel end plate is 20 mm thick, with a strength grade of Q235B, and the outer cross-section is the same as that of the special-shaped prefabricated supporting piles.

[0053] The buckle-type internal grouting special-shaped prefabricated support pile and construction method according to the present invention include the following steps:

[0054] Step 1: After the special-shaped prefabricated support piles are processed and produced in the factory, they are transported to the project site and the pile driving machine is in place. According to the design requirements, the pile test is first carried out to determine the technical indicators such as the pile driving speed and the maximum pressure value, and to check the pile driving machine equipment, construction technology and technical measures;

[0055] Step 2: When the pile driver is in place, start the platform leg lifting cylinder to calibrate the platform to a horizontal state. When the pile is 50cm deep in the soil, use the walking machine to adjust the verticality of the pile and the horizontality of the platform to ensure that the vertical deviation of the pile in both directions does not exceed 0.5%. After stabilization, press down the special-shaped prefabricated support piles one by one in a buckling manner, and continuously correct the vertical deviation in both directions;

[0056] Step 3: When using multi-section special-shaped prefabricated support piles, the pile head of the buried pile section should be 0.5 to 1.0m above the ground; when connecting the piles, the upper and lower sections of the piles should be kept straight, and the misalignment deviation should not exceed 2mm. Before welding, the end plates of the two sections of the piles should be cleaned with a steel brush until the groove reveals the metallic luster, and the upper section of the pile should be vertical before welding. Two welders should weld at the same time, first symmetrically spot weld 4 to 6 points on the circumference of the groove, and weld no less than 2 layers and 3 passes. Each layer of welding slag must be cleaned to ensure that the weld is continuous and full, and naturally cool for about 8 to 10 minutes.

[0057] Step 4: Carry out high-pressure rotary jet mixing construction in the gap formed by the parallel construction of every two special-shaped prefabricated piles. The triple pipe method should be used for the construction of high-pressure rotary jet piles. The air pressure should not be less than 0.7MPa, the cement slurry pressure should be greater than 25MPa, and the cement slurry pressure should not be less than 3.0MPa, or it can be determined by the construction unit based on on-site tests. The rotary jet lifting speed is 15-25cm / min, and the cement slurry flow rate is greater than 30L / min. When the grouting pipe is placed in the borehole and the nozzle reaches the designed elevation, grouting can be sprayed. After the jet grouting parameters reach the specified value, the grouting pipe is lifted according to the process requirements of the rotary jet pile, and the grouting is sprayed from bottom to top. The speed of the drill rod during the lifting process is 15-20r / min, and the overlap length of the grouting pipe section lifting should be greater than 100mm. High-pressure rotary jet piles use PO42.5 grade ordinary Portland cement. The total amount of cement and fly ash is 550kg / m 3 , cement: fly ash = 1:0.3, water-cement ratio of cement slurry 0.8;

[0058] Step 5: After the high-pressure jet-jet pile grouting construction is completed, the foundation pit is excavated and the soil is unloaded to the bottom elevation of the concrete crown beam (6) and the first concrete inner support (7), the steel bars are tied, and the concrete crown beam (6) and the first concrete inner support (7) are poured;

[0059] Step 6: After the strength of the concrete crown beam (6) on the top of the special-shaped precast pile and the first concrete inner support (7) reaches 80% of the design strength, continue to excavate the foundation pit symmetrically in layers and zones until the excavation reaches the bottom of the concrete purlin (8) and the second concrete inner support (9); at the same time, continuously observe the water seepage of the joints of the special-shaped precast supporting piles;

[0060] Step 7: The subsequent construction of the foundation pit project is the same as the ordinary foundation pit construction method.

[0061] The present invention has the following effects: 1. It reduces the scope of land used for foundation pit support structures and greatly develops the utilization rate of land; there is no mud discharge and dust generation during the construction process, which meets the requirements of green and environmentally friendly buildings; 2. The foundation pit support project is low in cost, the construction speed is fast, the total construction period is greatly shortened, and the benefit of rapid turnover of less funds is achieved; 3. The construction method is simple and has the conditions for wide promotion and application; 4. The special-shaped prefabricated piles are hollow sections, saving concrete; 5. After the parallel pile driving construction, small-diameter high-pressure rotary jet mixing piles are used to stop water in the formed gaps, and there is no need to set up a row of water-stopping piles, saving building materials; 6. The special-shaped prefabricated piles are produced in factories, the quality is controllable, and they can be mass-produced, and prefabricated piles can be applied with prestress, which further improves the stiffness of the pile body, gives full play to the material properties, and saves materials.

[0062] The above description is only a preferred embodiment of the present invention and should not be understood as a limitation of the present invention. Any modifications, equivalent substitutions and improvements made within the design ideas and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for a special-shaped prefabricated pile zipper support structure, characterized in that: The special-shaped prefabricated pile (1) comprises a special-shaped pile end plate (4) and a special-shaped prefabricated pile body; the special-shaped prefabricated pile body is made of concrete material and prestressed, a steel cage is arranged inside the special-shaped prefabricated pile body, and the belly of the special-shaped prefabricated pile is in the shape of a hollow circle; the special-shaped prefabricated pile (1) is an irregular short T-shape; the special-shaped pile end plate (4) is made of a steel plate with a thickness of not less than 20 mm and a steel grade not less than Q235B, and the cross-sectional shape of the special-shaped pile end plate (4) is the same as the cross-sectional shape of the special-shaped prefabricated pile (1); the belly of the special-shaped prefabricated pile is a hollow circle (2), wherein the diameter of the hollow circle (2) is 0.25 to 0.3 times the long side of the T-shape of the special-shaped prefabricated pile; The main construction steps are as follows: Step 1: After the special-shaped precast piles are processed and manufactured in the factory, they are transported to the construction site, the pile-driving machinery is in place, and the pile-driving machinery and equipment are debugged; Step 2: After the pile driver is in place and debugged, the special-shaped precast piles are slowly pressed down in sequence, symmetrically and staggered on both sides, to form a zipper-type support structure, and the two-way vertical deviation is continuously corrected; Step 3: When using multi-section special-shaped precast piles, the piles are connected on site for construction; Step 4: Small-diameter high-pressure rotary jet mixing piles (3) are constructed at the gap edge of two parallel special-shaped precast piles; Step 5: The concrete crown beam (6) and the first concrete inner support (7) are set at the top of the special-shaped precast piles; Step 6: Excavate the earth to the second support elevation, and set the concrete purlin (8) and the second concrete inner support (9); Step 7: Carry out subsequent foundation pit construction operations, and the subsequent construction of the foundation pit is the same as the ordinary foundation pit construction method; The concrete strength grade of the special-shaped precast pile body is C60-C80; the reinforcement ratio of the steel cage arranged inside the special-shaped precast pile body is not less than 0.2%, and the longitudinal reinforcement of the steel cage is made of prestressed concrete steel bars (5), and the stirrups are made of spiral high-strength steel bars; after the special-shaped precast pile is buckled, a small-diameter high-pressure rotary jet mixing pile (3) is constructed at the joint of two parallel special-shaped precast piles to form a high-pressure rotary jet mixing water stop body to block the gap formed by the parallel special-shaped precast piles; a concrete cap beam is arranged on the top of the special-shaped precast pile.

2. The construction method of a special-shaped prefabricated pile zipper support structure according to claim 1 is characterized by: The special-shaped prefabricated pile (1) is prestressed according to engineering requirements, wherein the prestress is applied before the concrete of the pile body is poured.

3. The construction method of a special-shaped prefabricated pile zipper support structure according to claim 1 is characterized by: The special-shaped prefabricated pile construction method comprises the following steps: staggering and symmetrically constructing the special-shaped prefabricated piles on site; two staggered special-shaped prefabricated piles are tightly buckled to form a chain-type support structure.

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