Construction method for reinforcing soft soil foundation through PHC pipe pile and PHC pipe pile structure

Abstract

The invention discloses a construction method for reinforcing a soft soil foundation through a PHC pipe pile. The construction method comprises the following steps that (1) preparation work is conducted; (2) foundation treatment; (3) paving filling materials; (4) coarse compaction; 5) repeating the operation; and (6) PHC pipe pile construction is conducted. According to the construction method, soft foundations such as a silt layer in a coastal area are treated by using materials such as coarse sand, geogrids or geotechnical cloth, so that the overall bearing capacity of the soft foundation ground is improved, the construction performability of a building pile foundation on the coastal soft foundation is met, and the construction efficiency is improved on the basis of not cleaning the soft foundations such as silt. After a series of measures, pile foundation construction is directly carried out; the reinforcing mechanism is connected with the two PHC pipe piles in a welding mode, and when the PHC pipe piles are driven into the designed depth, the ejection mechanism is used for pushing the inserting pieces to partially move out of the cylinder body, so that the inserting pieces are inserted into a foundation soil layer, additional friction force is provided for the pile bodies, and the bearing capacity of a pile foundation is improved.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a construction method for reinforcing a soft soil foundation with a PHC pipe pile and a PHC pipe pile structure. Background Art

[0002] In water conservancy and hydropower projects, it is often necessary to carry out construction on soft soil foundations in coastal areas. Generally, the soft foundation such as silt is cleaned first, and then construction is carried out to improve the bearing capacity of the foundation and ensure the stability of the project structure.

[0003] However, soft foundation cleaning operations will not only have an adverse impact on the surrounding environment, pollute the soil and groundwater, and destroy the ecological balance, but also when the soft soil foundation is serious, more processing time is required to achieve suitable construction conditions, which will lead to an extension of the overall construction time. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method for reinforcing soft soil foundation with PHC pipe piles and a PHC pipe pile structure to address the above-mentioned shortcomings, so as to achieve the purpose of directly carrying out pile foundation construction on the basis of soft foundation such as silt without cleaning.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a construction method for reinforcing soft soil foundation with PHC pipe piles, comprising the following steps:

[0006] 1) Preparation

[0007] First, the construction site needs to be surveyed and measured to determine the condition of the foundation and the scope of improvement that needs to be made. Then, a construction plan and drawings are prepared based on the actual situation, the materials and equipment required for construction are determined, and technical briefings and safety training are organized for construction personnel.

[0008] 2) Foundation treatment

[0009] Remove the surface debris and loose soil to make the foundation surface flat. Cleaning the surface debris includes removing trees, stones, weeds, etc. Then, use equipment such as excavators or forklifts to excavate the surface soil to the specified depth to remove the loose soil layer; finally, level and compact the excavated foundation to ensure that the foundation surface is flat and firm;

[0010] 3) Laying of filling materials

[0011] After the foundation treatment is completed, the geotextile is spread out on the construction area to ensure that the fabric is laid flat and fixed with fixings; then the sand and gravel granular cushion material is laid to fill the foundation gap; when laying the cushion material, it is necessary to first lay a layer of geotextile on the original soil layer, and then lay a layer of sand and gravel to form a coarse sand layer, and then lay another layer of geotextile, and finally lay a layer of sand and gravel to form a coarse sand layer, and repeat the above steps until the thickness of the filling material meets the bearing requirements;

[0012] 4) Rough compaction

[0013] After the filling material is laid, it needs to be compacted. During the compaction process, the sand and gravel should be added to the designed elevation in time through compaction. Attention should be paid to the number and speed of rolling to avoid over-compaction or under-compaction of the cushion material.

[0014] 5) Repeat the operation

[0015] After compaction is completed, the next layer of geotextile and cushion material is laid until the designed depth;

[0016] 6) PHC pile construction

[0017] The hammer method is adopted for construction, and the specific construction process is as follows: measurement and positioning - pile driver placement - pile position verification - pile lifting - centering correction - pile insertion - hammer pile sinking - pile connection - continue pile sinking - pile delivery - pile cutting / connecting; after the construction is completed, the piles are connected with steel mesh.

[0018] A PHC pipe pile structure is applied to the construction method of PHC pipe pile reinforcement of soft soil foundation, comprising a reinforcing mechanism and PHC pipe piles arranged at the upper and lower ends of the reinforcing mechanism, wherein the inner and outer diameters of the reinforcing mechanism are consistent with the inner and outer diameters of the PHC pipe piles; the reinforcing mechanism comprises a barrel and at least one insert arranged in the barrel, wherein the insert can extend obliquely downward from the barrel at an angle of 30° to 45°;

[0019] It also includes an ejection mechanism for pushing the insert out of the barrel.

[0020] Furthermore, the barrel is provided with a through hole for the insert to extend out of the barrel, the through hole is provided with a baffle for preventing the insert from moving out of the through hole, and a breaking groove is provided on a side of the baffle away from the insert.

[0021] Furthermore, a collar is provided in the barrel and is located at the bottom of the insert, a positioning pin is provided at the bottom of the collar and passes through the collar and extends to the top of the collar, an end plate is provided at the bottom of the positioning pin, a tension spring is provided between the end plate and the collar and is sleeved with the positioning pin, and a positioning groove is provided on the insert to match the positioning pin;

[0022] When the insert is located in the barrel, the tension spring is in a stretched state.

[0023] Furthermore, the ejection mechanism includes a column, and a downward pressure head for pushing the insert to move is detachably provided at the bottom end of the column, and the downward pressure head is in a truncated cone shape, and the diameter of the bottom end of the downward pressure head is smaller than the diameter of the top end, and the diameter of the column and the top diameter of the downward pressure head are both smaller than the inner diameter of the PHC pile, and a hammer plate is detachably provided at the top end of the column, and the diameter of the hammer plate is not less than the outer diameter of the PHC pile.

[0024] Furthermore, at least two arc blocks are arranged at the bottom of the hammer plate, a T-shaped block inserted into the hammer plate is arranged at the top of the arc block, and a slide groove is provided in the hammer plate for the T-shaped block to move toward and away from the column;

[0025] The outer diameter of the arc block is equal to the inner diameter of the PHC pile, and the inner diameter of the arc block is equal to the outer diameter of the column.

[0026] Furthermore, the column is formed by splicing a plurality of short rods with threads, and a threaded groove for installing the column is provided at the bottom end of the pressing head.

[0027] Furthermore, the insert piece includes a plate-shaped piece and a fork-shaped piece, and the opening direction of the fork-shaped piece points to the outside of the cylinder body.

[0028] The beneficial effects of the present invention are embodied in:

[0029] The present invention uses coarse sand, geogrid or geotextile and other materials to treat soft foundations such as silt layers in coastal areas, thereby improving the overall bearing capacity of the soft foundation surface, thereby meeting the feasibility of building pile foundation construction on coastal soft soil foundations, and achieving the purpose of directly carrying out pile foundation construction after a series of measures without cleaning soft foundations such as silt; the reinforcing mechanism is connected to two PHC pipe piles by welding, and when the PHC pipe piles are driven into the designed depth, the ejection mechanism is used to push the insert part out of the barrel, so that the insert is inserted into the foundation soil layer, providing additional friction for the pile body, and improving the bearing capacity of the pile foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the foundation reinforcement structure of the present invention;

[0031] Figure 2 It is a schematic diagram of the splicing of the reinforcing mechanism, the PHC pile and the ejection mechanism of the present invention;

[0032] Figure 3 It is a cross-sectional view of the reinforcing mechanism of the present invention;

[0033] Figure 4 It is a structural view of the ejection mechanism of the present invention.

[0034] In the figure:

[0035] 1. Reinforcement mechanism; 11. Cylinder body; 12. Insert; 13. Baffle; 14. Fracture groove; 15. Ring; 16. Positioning pin; 17. End plate; 18. Tension spring; 19. Positioning groove; 2. PHC pile; 3. Ejection mechanism; 31. Column; 32. Down pressure head; 33. Hammer plate; 34. Arc block; 35. T-block; 4. Original soil layer; 5. Geotextile; 6. Coarse sand layer. DETAILED DESCRIPTION

[0036] The technical solutions 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 only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] See also Figure 1-4 The present invention discloses a construction method for reinforcing a soft soil foundation with a PHC pipe pile, comprising the following steps:

[0038] 1) Preparation

[0039] First, the construction site needs to be surveyed and measured to determine the condition of the original soil layer 4 of the foundation and the scope that needs to be improved; then, a construction plan and construction drawings are prepared according to the actual situation, the materials and equipment required for construction are determined, and technical briefings and safety training are organized for construction personnel;

[0040] 2) Foundation treatment

[0041] Remove the surface debris and loose soil to make the foundation surface flat. Cleaning the surface debris includes removing trees, stones, weeds, etc. Then, use equipment such as excavators or forklifts to excavate the surface soil to the specified depth to remove the loose soil layer; finally, level and compact the excavated foundation to ensure that the foundation surface is flat and firm;

[0042] 3) Laying of filling materials

[0043] After the foundation treatment is completed, according to the requirements of the design drawings, the geotextile 5 is unfolded on the construction area to ensure that the fabric is laid flat without obvious wrinkles or waves, and the geotextile 5 is fixed to the soil using fixings (such as U-shaped nails, steel nails or geotextile clips, etc.); then the cushion material (sand and gravel granular material) is laid to form a coarse sand layer 6 to fill the foundation gap and improve the bearing capacity and stability of the foundation; when laying the cushion material, it is necessary to pay attention to the uniformity and thickness control of the material to ensure the quality of the cushion layer. The thickness of the sand and gravel filling material is generally laid according to a 50cm thick layer, and then a geogrid layer is laid on it, and then a layer of sand and gravel is laid, and the above steps are repeated until the thickness of the filling material meets the bearing requirements (generally, the thickness of the filling material is about 2.5m to 4.0m);

[0044] 4) Rough compaction

[0045] After the filling material is laid, it needs to be compacted to improve the density and stability of the filling material, so that the filling sand and gravel materials can meet the specified density requirements. During the compaction process, the sand and gravel materials should be replenished to the designed elevation in time through compaction. Attention should be paid to the number and speed of rolling to avoid over-compaction or under-compaction of the cushion material.

[0046] 5) Repeat the operation

[0047] After compaction is completed, the next layer of geotextile 5 and cushion material are laid until the designed depth, so as to improve the bearing capacity and stability of the foundation and ensure the safety and reliability of the project;

[0048] 6) PHC pile construction

[0049] The hammer method is adopted for construction, and the specific construction process is as follows: measurement and positioning - pile driver placement - pile position verification - pile lifting - centering correction - pile insertion - hammer pile sinking - pile connection - continue pile sinking - pile delivery - cutting / connecting piles; after the construction is completed, the piles are connected with steel mesh to improve the integrity of the pile foundation and reduce pile foundation settlement.

[0050] The present invention uses coarse sand, geogrid or geotextile 5 and other materials to treat soft foundations such as silt layers in coastal areas, thereby improving the overall bearing capacity of the soft foundation surface, thereby meeting the feasibility of building pile foundation construction on coastal soft soil foundations, and achieving the purpose of directly carrying out pile foundation construction after a series of measures without cleaning soft foundations such as silt.

[0051] In a specific implementation, a steel plate may be temporarily laid on the top of the uppermost coarse sand layer 6 to temporarily further increase the bearing capacity of the foundation.

[0052] A PHC pipe pile structure is applied to a construction method for reinforcing a soft soil foundation with PHC pipe piles, comprising a reinforcing mechanism 1 and PHC pipe piles 2 arranged at the upper and lower ends of the reinforcing mechanism 1, wherein the inner and outer diameters of the reinforcing mechanism 1 are consistent with the inner and outer diameters of the PHC pipe piles 2; the reinforcing mechanism 1 comprises a barrel 11 and at least one insert 12 arranged in the barrel 11, wherein the insert 12 can extend obliquely downward from the barrel 11 at an inclination angle of 30° to 45°;

[0053] The ejection mechanism 3 is also included for pushing the insert 12 out of the barrel 11 .

[0054] In this design, the reinforcing mechanism 1 is connected to the two PHC piles 2 by welding. When the PHC piles 2 are driven into the foundation, the insert 12 is inside the barrel 11 and does not affect the downward movement of the PHC piles 2. When the PHC piles 2 are driven into the designed depth, the ejection mechanism 3 is used to push the insert 12 partially out of the barrel 11, so that the insert 12 is inserted into the foundation soil layer, providing additional friction for the pile body and improving the bearing capacity of the pile foundation.

[0055] In a specific implementation, a pile tip needs to be welded to the bottom end of the PHC pile 2 located at the bottom to improve the smoothness of the insertion of the PHC pile 2.

[0056] In one embodiment, the barrel 11 is provided with a through hole for the insert 12 to extend out of the barrel 11 , a baffle 13 is provided in the through hole for preventing the insert 12 from moving out of the through hole, and a breaking groove 14 is provided on the side of the baffle 13 away from the insert 12 .

[0057] With such a design, after one end of the insert 12 is installed in the through hole of the barrel 11, the baffle 13 is used to prevent the insert 12 from moving out of the through hole due to the vibration of the pile hammer hitting the PHC pile 2, ensuring that the insert 12 will not have an adverse effect on the downward movement of the PHC pile 2. When the insert 12 is pushed by the ejection mechanism 3, the baffle 13 can bend or break at the fracture groove 14 due to the thrust, thereby not hindering the normal removal of the insert 12.

[0058] In one embodiment, a collar 15 is provided in the barrel 11 and is located at the bottom of the insert 12. A positioning pin 16 is provided at the bottom of the collar 15 and passes through the collar 15 and extends to the top of the collar 15. An end plate 17 is provided at the bottom of the positioning pin 16. A tension spring 18 is provided between the end plate 17 and the collar 15 and is sleeved with the positioning pin 16. A positioning groove 19 is provided on the insert 12 and is adapted to the positioning pin 16.

[0059] When the insert 12 is located in the barrel 11 , the tension spring 18 is in a stretched state.

[0060] With this design, when the positioning slot 19 on the inserting piece 12 moves to above the positioning pin 16, the tension spring 18 pulls the positioning pin 16 to be inserted into the positioning slot 19, thereby positioning and locking the inserting piece 12 and preventing the inserting piece 12 from retreating.

[0061] In one embodiment, the ejection mechanism 3 includes a column 31, and a downward pressure head 32 for pushing the insert 12 to move is detachably provided at the bottom end of the column 31. The downward pressure head 32 is in a truncated cone shape, and the diameter of the bottom end of the downward pressure head 32 is smaller than the diameter of the top end. The diameter of the column 31 and the top diameter of the downward pressure head 32 are both smaller than the inner diameter of the PHC pile 2. A hammer plate 33 is detachably provided at the top end of the column 31, and the diameter of the hammer plate 33 is not less than the outer diameter of the PHC pile 2.

[0062] With this design, after the PHC pile 2 is moved into position, the ejection mechanism 3 can be inserted into the PHC pile 2 from above the top of the PHC pile 2, and then the hammer plate 33 is hammered with a pile hammer to make the pressing head 32 push the insert 12 out.

[0063] In one embodiment, at least two arc blocks 34 are disposed at the bottom of the hammer plate 33, and a T-shaped block 35 inserted into the hammer plate 33 is disposed at the top of the arc block 34. A sliding groove is provided in the hammer plate 33 for the T-shaped block 35 to move toward and away from the column 31;

[0064] The outer diameter of the arc block 34 is equal to the inner diameter of the PHC pile 2 , and the inner diameter of the arc block 34 is equal to the outer diameter of the column 31 .

[0065] With this design, when the pile hammer is needed to hammer the PHC pile 2, the arc block 34 can be moved away from the column 31, so that the force of the pile hammer hammering the hammer plate 33 can be transmitted to the PHC pile 2 through the arc block 34. After the PHC pile 2 is moved into place, since the top of the PHC pile 2 is close to the ground, the arc block 34 can be pushed by ground construction workers to move towards the column 31, so that a gap is generated between the hammer plate 33 and the PHC pile 2, so that the continued hammering of the pile hammer will only push the insert 12 out without affecting the PHC pile 2, and then the ejection mechanism 3 can be placed under the pile hammer together with the PHC pile 2, eliminating the operation steps of repeatedly lifting and placing the pile hammer after the PHC pile 2 is moved into place, and at the same time, the outer wall of the arc block 34 is contacted and positioned with the inner wall of the PHC pile 2, so that the downward movement of the ejection mechanism 3 is more stable.

[0066] In one embodiment, the column 31 is formed by splicing a plurality of short rods with threads, and a threaded groove for installing the column 31 is disposed at the bottom end of the pressing head 32 .

[0067] This design can adjust the length of the ejection mechanism 3 according to the PHC piles 2 of different lengths to improve applicability. At the same time, multiple ejection mechanisms 3 can be spliced ​​together to achieve the effect of simultaneously pushing out the inserts 12 in the reinforcement mechanisms 1 of different layer heights.

[0068] It should be noted that a sinking groove may be opened on the top of the hammer plate 33 and a lifting ring may be provided in the sinking groove to facilitate the transfer of the ejection mechanism 3 after the construction is completed.

[0069] In one embodiment, the insert 12 includes a plate-shaped piece and a fork-shaped piece, and the opening direction of the fork-shaped piece points to the outside of the cylinder body 11. This design makes it easier for the insert 12 of the reinforcing mechanism 1 to be inserted into soil layers with different particle sizes.

[0070] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0071] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0072] In addition, "plurality" means two or more.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for reinforcing soft soil foundation with PHC pipe piles, characterized in that: The following steps are involved: 1) Preparation First, the construction site needs to be surveyed and measured to determine the condition of the foundation and the scope of improvement required; 2) Foundation treatment Remove surface debris and loose soil to make the foundation surface level; Then, the surface earth is excavated to the specified depth to remove the loose soil layer; finally, the excavated foundation is leveled and compacted to ensure that the foundation surface is flat and firm; 3) Laying of filling materials After the foundation treatment is completed, the geotextile is spread out on the construction area to ensure that the fabric is laid flat and fixed with fixings; then the sand and gravel granular cushion material is laid to fill the foundation gap; when laying the cushion material, it is necessary to first lay a layer of geotextile on the original soil layer, and then lay a layer of sand and gravel to form a coarse sand layer, and then lay another layer of geotextile, and finally lay a layer of sand and gravel to form a coarse sand layer, and repeat the above steps until the thickness of the filling material meets the bearing requirements; 4) Rough compaction Compact and replenish sand and gravel to the designed elevation in time; 5) Repeat the operation After compaction is completed, the next layer of geotextile and cushion material is laid until the designed depth; 6) PHC pile construction The hammer method is adopted for construction, and the specific construction process is as follows: measurement and positioning - pile driver placement - pile position verification - pile lifting - centering correction - pile insertion - hammer pile sinking - pile connection - continue pile sinking - pile delivery - pile cutting / connecting; after the construction is completed, the piles are connected with steel mesh.

2. A PHC pile structure, characterized in that: The construction method for reinforcing a soft soil foundation with PHC pipe piles as claimed in claim 1 comprises a reinforcing mechanism (1) and PHC pipe piles (2) arranged at the upper and lower ends of the reinforcing mechanism (1), wherein the inner and outer diameters of the reinforcing mechanism (1) are consistent with the inner and outer diameters of the PHC pipe piles (2); the reinforcing mechanism (1) comprises a barrel (11) and at least one insert (12) arranged in the barrel (11), wherein the insert (12) can extend obliquely downward from the barrel (11) at an angle of 30° to 45°; It also includes an ejection mechanism (3) for pushing the insert (12) out of the barrel (11).

3. A PHC pile structure according to claim 2, characterized in that: The barrel (11) is provided with a through hole for the insert (12) to extend out of the barrel (11), the through hole is provided with a baffle (13) for preventing the insert (12) from moving out of the through hole, and a breaking groove (14) is provided on a side of the baffle (13) away from the insert (12).

4. A PHC pile structure according to claim 2, characterized in that: A collar (15) is arranged inside the barrel (11) and is located at the bottom of the insert (12); a positioning pin (16) is arranged at the bottom of the collar (15) and passes through the collar (15) and extends to the top of the collar (15); an end plate (17) is arranged at the bottom of the positioning pin (16); a tension spring (18) is arranged between the end plate (17) and the collar (15) and is sleeved with the positioning pin (16); and a positioning groove (19) is arranged on the insert (12) and is adapted to the positioning pin (16); When the insert (12) is located in the barrel (11), the tension spring (18) is in a stretched state.

5. The PHC pile structure according to claim 2, characterized in that: The ejection mechanism (3) comprises a column (31), the bottom end of the column (31) is detachably provided with a pressing head (32) for pushing the insert (12) to move, the pressing head (32) is in a truncated cone shape, and the bottom diameter of the pressing head (32) is smaller than the top diameter, the diameter of the column (31) and the top diameter of the pressing head (32) are both smaller than the inner diameter of the PHC pile (2), and the top end of the column (31) is detachably provided with a hammer plate (33), and the diameter of the hammer plate (33) is not smaller than the outer diameter of the PHC pile (2).

6. A PHC pile structure according to claim 5, characterized in that: At least two arc blocks (34) are arranged at the bottom of the hammer plate (33), a T-shaped block (35) inserted into the hammer plate (33) is arranged at the top of the arc block (34), and a sliding groove is provided in the hammer plate (33) for the T-shaped block (35) to move toward and away from the column (31); The outer diameter of the arc block (34) is equal to the inner diameter of the PHC pile (2), and the inner diameter of the arc block (34) is equal to the outer diameter of the column (31).

7. A PHC pile structure according to claim 5, characterized in that: The column (31) is formed by splicing a plurality of short rods together by threads, and a thread groove for installing the column (31) is provided at the bottom end of the pressing head (32).

8. The PHC pile structure according to claim 2, characterized in that: The insert piece (12) comprises a plate-shaped piece and a fork-shaped piece, and the opening direction of the fork-shaped piece points to the outside of the cylinder body (11).

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