Design and construction method for combined tubular pile of coastal soft soil geologic house

Abstract

The invention discloses a design and construction method for a combined tubular pile of a coastal soft soil geologic house, which belongs to the technical field of tubular pile construction and comprises the following steps: step 1, construction preparation: step 1.1, overhead and underground obstacles on a construction site must be treated before tubular pile construction, the site surface should be flat, drainage should be smooth, and the construction time should be shortened; the method comprises the following steps of: (1) constructing a pile machine and meeting the ground bearing capacity required by the construction pile machine, (2) after the pile machine is transported into a construction site and installed in place, carefully checking the quality and the performance of each part of the pile machine, ensuring that mechanical equipment runs normally before construction, and regularly repairing and maintaining the mechanical equipment, and (3) putting the pile machine in place and tamping a shortcut to enable the pile machine to enter smoothly. By means of the mode, different types of pile type configuration and pile optimization can be processed in the coastal soft soil foundation, and on the premise that the structure safety is guaranteed and the design specification requirement is met, the cost can be effectively controlled, and the construction period can be effectively shortened.

Description

Technical Field

[0001] The invention relates to the technical field of pipe pile construction, in particular to a design and construction method of combined pipe piles for coastal soft soil houses. Background Art

[0002] Conventional building foundation pipe pile design generally adopts a pile type according to geological conditions and usage properties. For soft soil geology, large lateral force on the pile top, etc., design institutes often use PRC or PRHC pipe piles when designing pile foundations, without considering product processing capabilities, resulting in high costs and long construction periods. In coastal soft soil areas, all house units use a large number of PRHC prestressed concrete pipe piles, and the material cost is relatively high. Due to the large number of house units and the influence of local soft soil geological conditions, the demand for prestressed pipe piles is extremely large, and the total pile length is too long (up to more than 100,000 meters), of which the pile length with larger diameter accounts for the vast majority, and there is a small number of pile lengths with relatively small diameters. If a large number of large-diameter pipe piles are used, their market supply capacity is limited, and the construction difficulty should not be underestimated. From the perspective of cost-effectiveness, they are not as good as conventional smaller-diameter pipe piles. Therefore, considering the construction process, construction period, cost and other factors, it is necessary to design a combination pile to meet the demand.

[0003] The Chinese patent with publication number CN115748705A proposes a pipe pile construction method, including pre-construction preparation: site cleaning, site leveling, setting up anti-crowding ditches, setting up drainage wells, appropriately hardening the site, measuring and marking according to the designed pile position, and pipe piles entering the site; equipment entering the site: the pile driver is in place and the pile driver status is adjusted; prefabricated pile holes: drilling holes at points to form pile channels; pile positioning: lifting the pipe pile to the pile driver, and the pile driver clamps the pipe pile, adjusting the position of the pipe pile, and ensuring the verticality of the pile body; static pressure pile driving: the pile body is inserted into the pile driving hole, the verticality of the pipe pile is corrected at any time, and pressure is slowly applied to drive the pile to the designed elevation.

[0004] However, the technical solution of this patent has the following problems:

[0005] This patent is unable to handle different types of pile configurations and optimize construction in foundations in coastal soft soil.

[0006] Based on this, the present invention designs a combined pipe pile design and construction method for coastal soft soil houses to solve the above problems. Summary of the invention

[0007] In view of the above-mentioned shortcomings of the prior art, the present invention provides a design and construction method of combined pipe piles for coastal soft soil houses.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] A design and construction method of combined pipe piles for coastal soft soil houses, comprising the following steps:

[0010] Step 1: Construction preparation;

[0011] Step 1.1: Before constructing the piles, overhead and underground obstacles on the construction site must be dealt with. The site surface should be flat, drainage should be unobstructed, and the ground bearing capacity required by the construction pile driver should be met;

[0012] Step 1.2: After the pile driver is transported to the construction site and installed in place, the quality and performance of each part of the pile driver equipment should be carefully checked. Before construction, the mechanical equipment should be tested to ensure normal operation, and regular arrangements for mechanical equipment repair and maintenance should be made;

[0013] Step 1.3: Put the pile driver in place and compact the access road so that the pile driver can enter smoothly. If the foundation is soft, you can add a large steel plate or roadbed plate on the foundation to increase the bearing capacity;

[0014] Step 1.4, carry out the hoisting, transportation and stacking of pipe piles. The lifting points of pipe piles should be tied to the places specified in the design. They can be transported and sunk only after reaching 100%. When hoisting and transporting piles, the piles should be tied and packed tightly to prevent sliding or rolling. They must be lifted smoothly to avoid impact and vibration. When transporting piles horizontally, the strength should reach 100%. The pile driver and crane should be used in coordination. Flatbed trailers or trucks can be used for transportation. When loading, the pipe piles should be loaded firmly, supported and tied firmly. Before driving the piles, draw a ruler on the side of the pile body to record the pile driving. The marks can be evenly divided at 1m intervals.

[0015] Step 2: Pile position measurement;

[0016] The piling route is determined based on the on-site geological survey report, the plane size of the pile foundation, the density and depth of the piles, and the convenience of the pile driver. The pile group foundation is first set by applying pressure from the middle to the outside. After the piling route is determined, the position of the piles to be constructed is measured and released according to the route. The piles can be driven into the ground with a diameter of 6mm or bamboo, and the driving depth should not be less than 20cm. The position of the outer diameter of the pile is marked with lime with the pile position as the center, so that the first section of the pile can be accurately aligned.

[0017] Step 3: Pile driver in place;

[0018] Step 3.1, move the pile driver to the center of the pile position, observe the level meter and the plumb bob hanging on the pile sinker, level the machine body, and pad the surrounding areas to stabilize it;

[0019] Step 3.2: Use the center of the pile guide as the reference, align the heavy line hammer with the center of the pile tip, and find the pile position;

[0020] Step 3.3: Check the pile position. After the pile driver is initially in place, before the pile is inserted, the surveyor should re-measure and check the pile position to see if the pile position has moved. If there is any deviation, the pile driver should be adjusted to re-position the pile driver immediately to ensure that the center of the pile guide or the center of the pile cap is completely consistent with the designed pile position.

[0021] Step 3.4: After the pile driver is correctly positioned, two pile position control reference points with an angle of approximately 90 degrees are drawn according to the re-measured pile position, so as to observe whether the pile position deviation during insertion meets the requirements;

[0022] Step 4: Hoisting and pile insertion;

[0023] Step 4.1, the pile is hoisted into place, using a pile driver winch or a crane for single-point hoisting. The hoisting point is set by binding wire ropes. The setting position of the wire rope binding point is 0.31L or 0.29L away from the pile end. When the pile is fully hoisted, it is manually placed in the pile cap or pile guide accurately and quickly with the help of the pile driver, and then straightened into place;

[0024] Step 4.2, align the pile vertically with the center of the pile position, align the periphery of the pile with the white lime circle, slowly lower it into the soil, start the pile driver power device, press the pipe pile into the soil about 1.5m and pass through the backfill layer into the original soil layer. At the same time, observe whether the deviation of the pile when it is inserted into the soil meets the requirements based on the pile position control reference point. If the deviation meets the requirements, proceed to the next process. If not, pull out the pile body and re-insert it until the deviation requirements are met.

[0025] Step 5: Sinking and connecting piles;

[0026] Step 5.1: When sinking piles, the piles should be driven slowly and continuously. The pile body and pile cap should be on the same center line. If there is any deviation, it should be adjusted in time. The driving should not be stopped without special circumstances. The changes in the pile driving force and the speed of penetration should be observed at any time. If a sudden change in the speed of pile driving and penetration is found, it should be promptly found out whether it is due to geological reasons or pile body damage, and the relevant personnel of the supervision, survey and design units should be contacted in time;

[0027] Step 5.2, when the top of the pile is pressed to about 0.5m to 1.0m from the ground, stop applying pressure and prepare for pile connection. The steel end plate welding method is used for pile connection. Before pile connection, the end plate of the lower pile should be cleaned with a wire brush and a rag, and the positioning plate should be welded. Then the upper pile should be lifted and the upper pile (the pile end plate should also be cleaned) should be hung on the lower pile end plate. The upper and lower pile sections should be aligned and connected with the help of the positioning plate. When connecting the piles, the center line deviation of the upper and lower pile sections should not be greater than 5mm, and the node bending sagittal height should not be greater than 0.1% of the pile section;

[0028] Step 5.3, before welding the piles, two theodolites at 90 degrees to each other should be used to observe the verticality of the pile body in both directions, and the verticality of the upper pile should be adjusted to keep the verticality of the upper pile within 0.5% of the verticality of the lower pile. After the verticality adjustment, if there is a gap between the upper and lower pile end plates, the gap should be filled with a wedge-shaped pad of appropriate thickness before welding. Carbon dioxide gas shielded welding should be used for welding. Two welding machines should be used symmetrically. The weld should be continuous and full. When working on windy and rainy days, protective measures should be taken to protect against wind and rain to ensure welding quality;

[0029] Step 5.4: After the pile joint is welded, the quality inspector shall check the welding quality and report it to the supervisor for inspection. If it is qualified, it shall be cooled for more than 8 minutes before applying pressure;

[0030] Step 6: Send pile;

[0031] A special steel pipe pile driver is used for pile delivery, and its size should be consistent with the size of the pile body. Before the equipment enters the site, the pile delivery depth should be calculated in advance according to the construction drawings in order to configure the length of the pile driver. After entering the site, the pile driver should be marked with scale marks per meter with paint. The markings should be clear, and the last section of the pipe pile and the number of hammer blows per meter should be recorded in detail to control the effective pile length and pile top elevation;

[0032] Step 7: Final fight;

[0033] Record the last section of the pile in detail, the number of hammer blows per meter, control the effective pile length and pile top elevation. When the pile length reaches the effective pile length, calculate the number of hammer blows for the last meter, convert the penetration and the depth of the bearing layer. When the designed depth and the designed pile top elevation are reached, stop the injection. After stopping the injection, the construction worker will confirm the elevation position again and make a specific elevation record.

[0034] Step 8: Construction records;

[0035] When driving or delivering piles, the pile number, pile model and size, pile making date, ground elevation, number of hammer blows when piling is terminated, penetration, pile top elevation, and verticality deviation should be recorded in accordance with relevant standards. The weld joints should also be recorded in a hidden way. The records should be true, accurate, and complete.

[0036] Step 9: Pile foundation testing;

[0037] After the construction of the pipe pile is completed, the integrity of the pile body is first tested. The low-strain method is used to detect the defects and their locations of the pile body, and the pile body integrity category is determined. The single pile bearing capacity is tested by static load test, and the relevant technical parameters are recorded. The vertical bearing capacity limit value of the pipe pile is shown in the pipe pile design parameters. The engineering pile can only be constructed after the pipe pile meets the design requirements. The construction of the engineering pile should be carried out according to the construction process standards of the pipe pile;

[0038] In addition, for the pile analysis and parameter determination of the above steps;

[0039] (1) Pile analysis;

[0040] 1) Selection of pile driver: JZB-160 model 10.5 ton hammer or above can meet the pile sinking requirements;

[0041] 2) Construction parameters determined by pipe piles:

[0042] ① Pile type: PRCI800-130-B, PHC800-130-AB, strength C80, materials meet design and specification requirements;

[0043] ②Pile sinking records: the records are standardized, the text is clear, and all recorded data meet the requirements of the specifications;

[0044] ③ After the weld is completed, the natural cooling time should not be less than 8 minutes. It is strictly forbidden to use water cooling or to apply welding immediately after welding;

[0045] ④ Guarantee measures and suggestions taken during construction:

[0046] a. Select construction equipment with matching specifications and excellent performance, put the pile foundation in place, connect the power in time and then start the operation;

[0047] b. The construction site should be rolled first and temporary drainage should be done to ensure that the machinery can travel and support normally;

[0048] c. The pile position must be set out in place and clearly marked to avoid pile deviation;

[0049] d. The verticality of the piles shall be controlled in advance and checked by using two theodolites, which shall be placed in the vertical direction respectively for real-time monitoring to avoid deviation of the verticality of the piles;

[0050] (2) Determine parameters;

[0051] 1) Selection of pile driver: JZB-160 model with 10.5 ton hammer or above can meet the pile sinking requirements and the drop distance is controlled at 1.5-2.2 meters, which can meet the construction of 600 and 800 pipe piles;

[0052] 2) The pile body integrity test and low strain test in the pile foundation report were all qualified;

[0053] ① Pile integrity test: low strain detection, all tests are qualified;

[0054] ② Final hammer conclusion: The bearing layer of the single dormitory is fine round gravel soil, and the bearing layer of the signal building is silty clay, but the lower layer is fine round gravel soil, and the penetration value is low. In order to ensure the integrity of the pile body and avoid defects in the pile body and pile head, the penetration value is controlled to be no less than 3cm / 10 hits according to the specification;

[0055] ③ According to the results of low-strain detection and single pile static load test, the construction technology and the depth of the pile end entering the bearing layer can meet the design and specification requirements;

[0056] ④ The parameters determined in the pile test plan are feasible and can be used to guide the construction of prestressed pipe piles in this project;

[0057] ⑤ The control parameters of pile driving are combined with the geological survey report and the "Technical Standard for Prestressed Concrete Pipe Piles" (JGJ / T406-2017), and the test parameters are as follows:

[0058]

[0059] ⑥ For the construction of prestressed pipe piles, monitoring at surrounding measuring points revealed that the influence range of pile sinking is 15 to 20 meters.

[0060] Compared with the prior art, the invention has the following beneficial effects: the invention processes overhead and underground obstacles at the construction site before construction, levels the site, and unclogs drainage to ensure that the ground bearing capacity meets the requirements of the pile driver; after the pile driver is in place, it is inspected and debugged, and the access road is compacted or steel plates are laid to enhance the bearing capacity of the foundation; when the pipe piles are hoisted, transported, and stacked, it is ensured that the strength meets the standard and the operation is stable; the pile position measurement determines the piling route according to the geological survey report, measures and places the pile position, and the pile driver needs to level the fuselage, find the pile position and verify it when it is in place; when hoisting and inserting the pile, the pipe pile is lifted at a single point and the pile cap or pile guide is accurately placed; The pile is driven vertically into the soil, pressed 1.5m through the backfill layer to the original soil, ensuring compliance with the deviation regulations, and continuously applied during pile sinking. The steel end plate welding method is used to strictly control the deviation of the center line of the upper and lower piles, the verticality, etc., quality inspection and cooling are carried out after welding. A special pile driver is used to deliver the piles, the depth is calculated in advance, and scale marks are made. Key data is recorded at the end of the driving, and the driving is stopped when the standard is met. Records are kept throughout the construction process. The present invention can handle different types of pile configurations and pile optimization in the foundation of coastal soft soil geology. On the premise of ensuring structural safety and meeting the requirements of design specifications, it can effectively control costs and save construction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0062] Figure 1 This is a process flow chart of the prestressed pipe pile of the present invention;

[0063] Figure 2 It is a plan view of the pile foundation arrangement of the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] The present invention will be further described below in conjunction with the embodiments.

[0066] Embodiment 1: In some embodiments, please refer to Figure 1-Figure 2 , a design and construction method of combined pipe piles for coastal soft soil houses, comprising the following steps:

[0067] Step 1: Construction preparation;

[0068] Step 1.1: Before constructing the piles, overhead and underground obstacles on the construction site must be dealt with. The site surface should be flat, drainage should be unobstructed, and the ground bearing capacity required by the construction pile driver should be met;

[0069] Step 1.2: After the pile driver is transported to the construction site and installed in place, the quality and performance of each part of the pile driver equipment should be carefully checked. Before construction, the mechanical equipment should be tested to ensure normal operation, and regular arrangements for mechanical equipment repair and maintenance should be made;

[0070] Step 1.3: Put the pile driver in place and compact the access road so that the pile driver can enter smoothly. If the foundation is soft, you can add a large steel plate or roadbed plate on the foundation to increase the bearing capacity;

[0071] Step 1.4, carry out the hoisting, transportation and stacking of pipe piles. The lifting points of pipe piles should be tied to the places specified in the design. They can be transported and sunk only after reaching 100%. When hoisting and transporting piles, the piles should be tied and packed tightly to prevent sliding or rolling. They must be lifted smoothly to avoid impact and vibration. When transporting piles horizontally, the strength should reach 100%. The pile driver and crane should be used in coordination. Flatbed trailers or trucks can be used for transportation. When loading, the pipe piles should be loaded firmly, supported and tied firmly. Before driving the piles, draw a ruler on the side of the pile body to record the pile driving. The marks can be evenly divided at 1m intervals.

[0072] Step 2: Pile position measurement;

[0073] The piling route is determined based on the on-site geological survey report, the plane size of the pile foundation, the density and depth of the piles, and the convenience of the pile driver. The pile group foundation is first set by applying pressure from the middle to the outside. After the piling route is determined, the position of the piles to be constructed is measured and released according to the route. The piles can be driven into the ground with a diameter of 6mm or bamboo, and the driving depth should not be less than 20cm. The position of the outer diameter of the pile is marked with lime with the pile position as the center, so that the first section of the pile can be accurately aligned.

[0074] Step 3: Pile driver in place;

[0075] Step 3.1, move the pile driver to the center of the pile position, observe the level meter and the plumb bob hanging on the pile sinker, level the machine body, and pad the surrounding areas to stabilize it;

[0076] Step 3.2: Use the center of the pile guide as the reference, align the heavy line hammer with the center of the pile tip, and find the pile position;

[0077] Step 3.3: Check the pile position. After the pile driver is initially in place, before the pile is inserted, the surveyor should re-measure and check the pile position to see if the pile position has moved. If there is any deviation, the pile driver should be adjusted to re-position the pile driver immediately to ensure that the center of the pile guide or the center of the pile cap is completely consistent with the designed pile position.

[0078] Step 3.4: After the pile driver is correctly positioned, two pile position control reference points with an angle of approximately 90 degrees are drawn according to the re-measured pile position, so as to observe whether the pile position deviation during insertion meets the requirements;

[0079] Step 4: Hoisting and pile insertion;

[0080] Step 4.1, the pile is hoisted into place, using a pile driver winch or a crane for single-point hoisting. The hoisting point is set by binding wire ropes. The setting position of the wire rope binding point is 0.31L or 0.29L away from the pile end. When the pile is fully hoisted, it is manually placed in the pile cap or pile guide accurately and quickly with the help of the pile driver, and then straightened into place;

[0081] Step 4.2, align the pile vertically with the center of the pile position, align the periphery of the pile with the white lime circle, slowly lower it into the soil, start the pile driver power device, press the pipe pile into the soil about 1.5m and pass through the backfill layer into the original soil layer. At the same time, observe whether the deviation of the pile when it is inserted into the soil meets the requirements based on the pile position control reference point. If the deviation meets the requirements, proceed to the next process. If not, pull out the pile body and re-insert it until the deviation requirements are met.

[0082] Step 5: Sinking and connecting piles;

[0083] Step 5.1: When sinking piles, the piles should be driven slowly and continuously. The pile body and pile cap should be on the same center line. If there is any deviation, it should be adjusted in time. The driving should not be stopped without special circumstances. The changes in the pile driving force and the speed of penetration should be observed at any time. If a sudden change in the speed of pile driving and penetration is found, it should be promptly found out whether it is due to geological reasons or pile body damage, and the relevant personnel of the supervision, survey and design units should be contacted in time;

[0084] Step 5.2, when the top of the pile is pressed to about 0.5m to 1.0m from the ground, stop applying pressure and prepare for pile connection. The steel end plate welding method is used for pile connection. Before pile connection, the end plate of the lower pile should be cleaned with a wire brush and a rag, and the positioning plate should be welded. Then the upper pile should be lifted and the upper pile (the pile end plate should also be cleaned) should be hung on the lower pile end plate. The upper and lower pile sections should be aligned and connected with the help of the positioning plate. When connecting the piles, the center line deviation of the upper and lower pile sections should not be greater than 5mm, and the node bending sagittal height should not be greater than 0.1% of the pile section;

[0085] Step 5.3, before welding the piles, two theodolites at 90 degrees to each other should be used to observe the verticality of the pile body in both directions, and the verticality of the upper pile should be adjusted to keep the verticality of the upper pile within 0.5% of the verticality of the lower pile. After the verticality adjustment, if there is a gap between the upper and lower pile end plates, the gap should be filled with a wedge-shaped pad of appropriate thickness before welding. Carbon dioxide gas shielded welding should be used for welding. Two welding machines should be used symmetrically. The weld should be continuous and full. When working on windy and rainy days, protective measures should be taken to protect against wind and rain to ensure welding quality;

[0086] Step 5.4: After the pile joint is welded, the quality inspector shall check the welding quality and report it to the supervisor for inspection. If it is qualified, it shall be cooled for more than 8 minutes before applying pressure;

[0087] Step 6: Send pile;

[0088] A special steel pipe pile driver is used for pile delivery, and its size should be consistent with the size of the pile body. Before the equipment enters the site, the pile delivery depth should be calculated in advance according to the construction drawings in order to configure the length of the pile driver. After entering the site, the pile driver should be marked with scale marks per meter with paint. The markings should be clear, and the last section of the pipe pile and the number of hammer blows per meter should be recorded in detail to control the effective pile length and pile top elevation;

[0089] Step 7: Final fight;

[0090] Record the last section of the pile in detail, the number of hammer blows per meter, control the effective pile length and pile top elevation. When the pile length reaches the effective pile length, calculate the number of hammer blows for the last meter, convert the penetration and the depth of the bearing layer. When the designed depth and the designed pile top elevation are reached, stop the injection. After stopping the injection, the construction worker will confirm the elevation position again and make a specific elevation record.

[0091] Step 8: Construction records;

[0092] When driving or delivering piles, the pile number, pile model and size, pile making date, ground elevation, number of hammer blows when piling is terminated, penetration, pile top elevation, and verticality deviation should be recorded in accordance with relevant standards. The weld joints should also be recorded in a hidden way. The records should be true, accurate, and complete.

[0093] Step 9: Pile foundation testing;

[0094] After the construction of the pipe pile is completed, the integrity of the pile body is first tested. The low-strain method is used to detect the defects and their locations of the pile body, and the pile body integrity category is determined. The single pile bearing capacity is tested by static load test, and the relevant technical parameters are recorded. The vertical bearing capacity limit value of the pipe pile is shown in the pipe pile design parameters. The engineering pile can only be constructed after the pipe pile meets the design requirements. The construction of the engineering pile should be carried out according to the construction process standards of the pipe pile;

[0095] In addition, for the pile analysis and parameter determination of the above steps;

[0096] (1) Pile analysis;

[0097] 1) Selection of pile driver: JZB-160 model 10.5 ton hammer or above can meet the pile sinking requirements;

[0098] 2) Construction parameters determined by pipe piles:

[0099] ① Pile type: PRCI800-130-B, PHC800-130-AB, strength C80, materials meet design and specification requirements;

[0100] ②Pile sinking records: the records are standardized, the text is clear, and all recorded data meet the requirements of the specifications;

[0101] ③ After the weld is completed, the natural cooling time should not be less than 8 minutes. It is strictly forbidden to use water cooling or to apply welding immediately after welding;

[0102] ④ Guarantee measures and suggestions taken during construction:

[0103] a. Select construction equipment with matching specifications and excellent performance, put the pile foundation in place, connect the power in time and then start the operation;

[0104] b. The construction site should be rolled first and temporary drainage should be done to ensure that the machinery can travel and support normally;

[0105] c. The pile position must be set out in place and clearly marked to avoid pile deviation;

[0106] d. The verticality of the piles shall be controlled in advance and checked by using two theodolites, which shall be placed in the vertical direction respectively for real-time monitoring to avoid deviation of the verticality of the piles;

[0107] (2) Determine parameters;

[0108] 1) Selection of pile driver: JZB-160 model with 10.5 ton hammer or above can meet the pile sinking requirements and the drop distance is controlled at 1.5-2.2 meters, which can meet the construction of 600 and 800 pipe piles;

[0109] 2) The pile body integrity test and low strain test in the pile foundation report were all qualified;

[0110] ① Pile integrity test: low strain detection, all tests are qualified;

[0111] ② Final hammer conclusion: The bearing layer of the single dormitory is fine round gravel soil, and the bearing layer of the signal building is silty clay, but the lower layer is fine round gravel soil, and the penetration value is low. In order to ensure the integrity of the pile body and avoid defects in the pile body and pile head, the penetration value is controlled to be no less than 3cm / 10 hits according to the specification;

[0112] ③ According to the results of low-strain detection and single pile static load test, the construction technology and the depth of the pile end entering the bearing layer can meet the design and specification requirements;

[0113] ④ The parameters determined in the pile test plan are feasible and can be used to guide the construction of prestressed pipe piles in this project;

[0114] ⑤ The control parameters of pile driving are combined with the geological survey report and the "Technical Standard for Prestressed Concrete Pipe Piles" (JGJ / T406-2017), and the test parameters are as follows:

[0115]

[0116] ⑥ For the construction of prestressed pipe piles, monitoring at surrounding measuring points revealed that the influence range of pile sinking is 15 to 20 meters.

[0117] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design and construction method for combined pipe piles for coastal soft soil houses, characterized in that: The following steps are involved: Step 1: Construction preparation; Step 2: Pile position measurement; Step 3: Pile driver in place; Step 4: Hoisting and pile insertion; Step 5: Sinking and connecting piles; Step 5.1: When sinking piles, the piles should be driven slowly and continuously. The pile body and pile cap should be on the same center line. If there is any deviation, it should be adjusted in time. The driving should not be stopped without special circumstances. The changes in the pile driving force and the speed of penetration should be observed at any time. If a sudden change in the speed of pile driving and penetration is found, it should be promptly found out whether it is due to geological reasons or pile body damage, and the relevant personnel of the supervision, survey and design units should be contacted in time; Step 5.2, when the top of the pile is pressed to about 0.5m to 1.0m from the ground, stop applying pressure and prepare for pile connection. The steel end plate welding method is used for pile connection. Before pile connection, the end plate of the lower pile should be cleaned with a wire brush and a rag, and the positioning plate should be welded. Then the upper pile should be lifted and the upper pile (the pile end plate should also be cleaned) should be hung on the lower pile end plate. The upper and lower pile sections should be aligned and connected with the help of the positioning plate. When connecting the piles, the center line deviation of the upper and lower pile sections should not be greater than 5mm, and the node bending sagittal height should not be greater than 0.1% of the pile section; Step 5.3, before welding the piles, two theodolites at 90 degrees to each other should be used to observe the verticality of the pile body in both directions, and the verticality of the upper pile should be adjusted to keep the verticality of the upper pile within 0.5% of the verticality of the lower pile. After the verticality adjustment, if there is a gap between the upper and lower pile end plates, the gap should be filled with a wedge-shaped pad of appropriate thickness before welding. Carbon dioxide gas shielded welding should be used for welding. Two welding machines should be used symmetrically. The weld should be continuous and full. When working on windy and rainy days, protective measures should be taken to protect against wind and rain to ensure welding quality; Step 6: Send pile; Step 7: Final fight; Step 8: Construction records; Step 9: Pile foundation testing.

2. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 1 is characterized in that: Step 1 also includes: Step 1.1, before the construction of the pile, the overhead and underground obstacles on the construction site must be dealt with, the site surface should be flat, the drainage should be unobstructed, and the ground bearing capacity required by the construction pile driver should be met; Step 1.2: After the pile driver is transported to the construction site and installed in place, the quality and performance of each part of the pile driver equipment should be carefully checked. Before construction, the mechanical equipment should be tested to ensure normal operation, and regular arrangements for mechanical equipment repair and maintenance should be made; Step 1.3: Put the pile driver in place and compact the access road so that the pile driver can enter smoothly. If the foundation is soft, you can add a large steel plate or roadbed plate on the foundation to increase the bearing capacity; Step 1.4: Hoist, transport and stack the pipe piles. The lifting points of the pipe piles should be tied to the places specified in the design. They can be transported and sunk only after reaching 100%. When hoisting and transporting the piles, the piles should be tied and tightly packed to prevent sliding or rolling. They must be lifted smoothly to avoid impact and vibration. When transporting the piles horizontally, the strength should reach 100%. The pile driver and crane should be used in coordination. Flatbed trailers or trucks can be used for transportation. When loading, the pipe piles should be loaded firmly, supported and tied firmly. Before the piles are driven in, a ruler should be drawn on the side of the pile body to record the driving. The marks can be evenly divided at 1m intervals.

3. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 2 is characterized in that: Step 2 also includes: determining the piling route based on the on-site geological survey report, the plane size of the pile foundation, the density and depth of the piles, the ease of movement of the pile driver and other factors, and setting the pressure on the pile group foundation from the middle to the outside. After the piling route is determined, the position of the piles to be constructed is measured and laid out according to the route. The piles can be driven into the ground with steel bars or bamboos with a diameter of 6 mm, and the driving depth should not be less than 20 cm. The position of the outer diameter of the pile is marked with lime with the pile position as the center, so that the first section of the pile can be accurately positioned.

4. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 3 is characterized in that: Step three also includes: Step 3.1, move the pile driver to the center of the pile position, observe the level meter and the plumb bob hanging on the pile sinker, level the machine body, and pad the surrounding areas to stabilize it; Step 3.2: Use the center of the pile guide as the reference, align the heavy line hammer with the center of the pile tip, and find the pile position; Step 3.3: Check the pile position. After the pile driver is initially in place, before the pile is inserted, the surveyor should re-measure and check the pile position to see if the pile position has moved. If there is any deviation, the pile driver should be adjusted to re-position the pile driver immediately to ensure that the center of the pile guide or the center of the pile cap is completely consistent with the designed pile position. Step 3.4: After the pile driver is correctly positioned, two pile position control reference points with an angle of approximately 90 degrees are drawn according to the re-measured pile position, so as to observe whether the deviation of the pile into the soil meets the requirements during insertion.

5. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 4 is characterized in that: Step 4 also includes: Step 4.1, hoisting the pipe pile into place, using a pile driver winch or a crane for single-point hoisting, the hoisting point is set by a bundled wire rope, the setting position of the wire rope binding point is 0.31L or 0.29L away from the pile end, when the pile is fully hoisted, it is manually placed in the pile cap or pile guide accurately and quickly with the help of the pile driver, and then straightened into place; Step 4.2, align the pile vertically with the center of the pile position, align the periphery of the pile with the white lime circle, slowly lower it into the soil, start the pile driver power device, press the pipe pile into the soil about 1.5m and pass through the backfill layer into the original soil layer. At the same time, observe whether the deviation of the pile when it is inserted into the soil meets the requirements based on the pile position control reference point. If the deviation meets the requirements, proceed to the next process. If not, pull out the pile body and re-insert it until the deviation requirements are met.

6. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 5 is characterized in that: Step five also includes: Step 5.4, when the pile joint welding is completed, the quality inspector shall check the welding quality and report it to the supervisor for inspection. After passing the inspection, it shall be cooled for more than 8 minutes before applying pressure.

7. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 6 is characterized in that: Step six also includes: the piles are delivered using a special steel pipe pile driver, the size of which should be consistent with the size of the pile body. Before the equipment enters the site, the pile delivery depth should be calculated in advance according to the construction drawings in order to configure the length of the pile driver. After entering the site, the pile driver should be marked with scale marks per meter with paint. The markings should be clear, and the last section of the pipe pile and the number of hammer blows per meter should be recorded in detail to control the effective pile length and pile top elevation.

8. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 7 is characterized in that: Step seven also includes: recording the last section of the pile in detail, the number of hammer blows per meter, controlling the effective pile length and the pile top elevation; when the pile length reaches the effective pile length, calculating the number of hammer blows for the last meter, converting the penetration degree and the depth into the bearing layer; when the designed depth and the designed pile top elevation are reached, stopping the injection; after stopping the injection, the construction worker shall confirm the elevation position again and make specific elevation records.

9. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 8, characterized in that: Step eight also includes: when piling or delivering piles, original records of pile number, pile model and size, pile making date, ground elevation, number of hammer blows when piling is terminated, penetration, pile top elevation, verticality deviation should be made according to relevant standards, and hidden records of welds should also be made. The records should be true, accurate and complete.

10. The design and construction method of combined pipe piles for coastal soft soil houses according to claim 9, characterized in that: Step nine also includes: after the construction of the pipe pile is completed, the integrity of the pile body is first tested, and the defects and their locations of the pile body are detected by the low strain method, and the pile body integrity category is determined. The single pile bearing capacity is tested by static load test, and the relevant technical parameters are recorded. The vertical bearing capacity limit value of the single pipe pile can be found in the pipe pile design parameters. The engineering piles can only be constructed after the pipe piles meet the design requirements. The construction of engineering piles should be carried out according to the construction process standards of the pipe piles.

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