A foundation reinforcement method using rectangular pipe jacking in soft ground conditions

Abstract

A foundation reinforcement method for rectangular pipe jacking in soft soil conditions. This method relates to a foundation reinforcement method for rectangular pipe jacking in soft soil conditions. A tool section is provided between the machine head and the first pipe section, and a pile driving hole is provided on the bottom plate of the tool section. 1) The machine head stops at the foundation to be reinforced. 2) Pipe piles are driven into the lower stratum. 3) The machine head moves to the next stroke and repeats step 2. 4) Excavation is completed, and the tool section follows the machine head into the receiving well. 5) Thick clay is injected into the bottom surface of the pipe section. 6) Curing completes the process. The present invention is unaffected by ground environmental conditions in soft soil conditions, does not require vertical reinforcement from the ground, does not require damage to the pipe section structure, and does not affect rectangular pipe jacking operations. Construction disturbance is minimal, efficiency is high, and uneven settlement, pipe section misalignment, and disconnection can be prevented. The present invention uses the tool section as a pile driving platform, and excavation and pile driving are performed step by step. The construction process is user-friendly, improving construction quality and waterproofing effects.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering construction, and in particular to a foundation reinforcement method when rectangular jacking pipe construction is adopted under soft stratum conditions. Background Art

[0002] In recent years, rectangular pipe jacking technology has developed rapidly in the field of underground engineering in my country. It has been widely used in the construction of underground projects such as power pipeline corridors, urban underground integrated pipeline corridors, drainage box culverts, subway entrances and exits, underground vehicle tunnels, subway tunnels, etc. It is suitable for soft soil, clay soil, silty soil, sandy soil, gravel, soft rock and other strata.

[0003] In alluvial plains such as those in my country's Pearl River Delta and Yangtze River Delta, the rectangular pipe jacking method is in high demand. However, these areas are plagued by numerous soft strata, such as silt and muddy soils, with extremely low foundation bearing capacities of only 30kPa to 50kPa. Pipe jacking in such low-bearing-capacity strata is prone to uneven settlement or excessive post-construction settlement, leading to misalignment or disconnection of pipe sections. This, in turn, reduces the overall rigidity of the pipe jacking tunnel / passageway and causes failure of the longitudinal waterproofing structure, seriously impacting the operation and use of the completed tunnel / passageway.

[0004] This technical field currently employs two methods: prestressing technology and pre-reinforcement using jet grouting or mixing piles. While prestressing technology can improve structural rigidity and waterproofing, it has drawbacks such as high construction precision requirements and the susceptibility of steel strands to rust. While jet grouting and mixing pile reinforcement methods can enhance foundation bearing capacity, their implementation in complex urban environments is limited by the impact of surface traffic, pipelines, and existing structures, resulting in limited vertical reinforcement conditions. Furthermore, there are two major issues with pre-reinforced strata: first, cement brittleness is easily squeezed and fractured by the surrounding soft soil, and fractured bodies can easily get stuck in the cutterhead of the pipe jacking machine, affecting excavation efficiency; second, large-scale reinforcement can exacerbate wear on the cutterhead and even lead to cutting failure, increasing the risk of pipe jacking failure.

[0005] Therefore, based on the above practical problems, those skilled in the art have proposed a patent application for "Method for Reinforcement of Soft Soil Foundation in Pipe Jacking Construction, CN 113202097 A". This patent requires reserving pile holes for existing pipe jacking sections. The reserved pile holes have a great impact on the overall strength and rigidity of the pipe section structure. The entire pipe jacking section channel requires a large number of reserved pile holes, and it is inevitable that the sealing treatment will be poor, which will affect the internal waterproofing of the pipe section, reduce construction quality, increase costs, and affect use.

[0006] Therefore, when implementing rectangular pipe jacking construction under soft strata conditions, how to avoid uneven settlement and deformation, pipe segment misalignment and disconnection, make full use of traditional integral pipe segments, and simultaneously achieve the reinforcement of the lower foundation while taking into account waterproof performance has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0007] In response to the above technical problems, the present invention provides a foundation reinforcement method for rectangular pipe jacking construction under soft stratum conditions, which has the advantages of not being affected by ground environmental conditions, not requiring vertical reinforcement from the ground, not requiring destruction of the pipe joint structure, and not affecting the rectangular pipe jacking operation. In addition, the construction disturbance in the pipe jacking channel is weak and the efficiency is high, which can achieve the purpose of preventing uneven settlement, pipe joint misalignment, and disconnection after rectangular pipe jacking work.

[0008] The technical solution of the present invention is as follows: a starting well and a receiving well are opened on the ground surface; a rectangular pipe jacking machine is excavated from the starting well to the receiving well; rectangular pipe sections are connected step by step during the excavation process to form a channel composed of several rectangular pipe sections; a tool section is provided between the head of the rectangular pipe jacking machine and the first pipe section; a pile pressure hole is opened on the bottom plate of the tool section;

[0009] Then, follow these steps:

[0010] 1) The machine head starts to excavate from the starting well and stops at the location where the foundation is to be reinforced;

[0011] 2) In the tool section behind the machine head, use the pile driving device to press the pipe piles into the lower stratum, and perform the pile driving and pile delivery operations for each hole position within the current stroke until all the pipe piles reach the preset depth requirements;

[0012] 3) The machine head moves to the next stroke, the length of which is the same as the length of the single pipe section, stops and repeats the pile pressing and pile delivery operations in step 2);

[0013] 4) After the excavation is completed, the tool section enters the receiving well along with the excavator head;

[0014] 5) Pressurize the bottom surface of the pipe section with curable thick clay several times to compact and fill the soil between the bottom of the pipe section and the top of the pile;

[0015] 6) The thick clay solidifies and is finished.

[0016] Furthermore, the tool section is a steel structure, and a self-propelled hoisting device is provided on the inner top surface of the tool section for hoisting prefabricated pipe piles transported from the starting well, and the pipe piles are solid piles;

[0017] The bottom surface of the tool section is provided with upright ribs perpendicular to the traveling direction, and the pile-pressing holes are opened on the bottom plate between adjacent ribs.

[0018] Furthermore, the pile driving device includes a base, a guide column, a cylinder seat, a cylinder and a clamp. The guide column is fixedly connected to the base, the cylinder seat is fixedly arranged on the top of the guide column, the clamp is provided with a clamp hole matching the pipe pile and guide holes arranged at four corners, the clamp is movably connected to the guide column, and the piston rod of the cylinder is used to push the clamp downward; two clamps are provided, the bottom clamp is used to fix the pressed pipe pile and expose the joint for convenient pile connection and prevent it from tilting, and the upper clamp is used to hold the pipe pile to be pressed and press the pile downward under the action of the cylinder; the clamp is fixed in a hydraulic form.

[0019] Furthermore, a pile driver track is provided on the base of the pile driving device to facilitate the displacement of the pile driving device; an easily disassembled anchoring device is also provided to facilitate the stability of the entire device during pile driving; the pile driver track does not affect the internal operation of the rectangular jacking pipe.

[0020] Furthermore, a self-propelled hoisting device is provided on the top of the tool section, and tracks should be set in the vertical and horizontal directions, corresponding to the track positions used by the pile driving device, to facilitate hoisting operations during pile driving and pile connection.

[0021] Furthermore, a pile hole anti-seepage device is provided on each of the pile holes, and the pile hole anti-seepage device includes a cylindrical base, a sealing bowl, a ball valve and a handle; the ball valve has a center hole adapted to the outer diameter of the pipe pile, the ball valve is movably connected to the cylindrical base via a rotation pin, and the handle is used to control the reciprocating rotation of the ball valve;

[0022] The sealing bowl is made of elastic material and is fixedly arranged on the inner wall of the cylindrical base. The sealing bowl has an inner spherical surface adapted to the spherical surface of the ball valve for achieving sealing.

[0023] Furthermore, it also includes a water-stop sleeve detachably connected to the top of the cylindrical base through a threaded structure, and the inner tube of the water-stop sleeve is provided with at least two elastic water-stop rings with an inner diameter smaller than the outer diameter of the pipe pile.

[0024] Furthermore, a protruding structure is provided on the outer surface of the water-stop sleeve to facilitate the rotation operation.

[0025] Furthermore, the medium pressure pile operation in step 2) is specifically as follows:

[0026] 2.1) Laying a process steel plate on the top surface of the rib plate outside the pile hole anti-seepage device, and placing the pile driving device on the process steel plate;

[0027] 2.2) Lift the pipe pile to the top of the pile hole anti-seepage device and align the pipe pile with the top of the water-stop sleeve. Use the pile's own weight or the pile-pressing device to press the pile down for a certain distance until the elastic water-stop ring covers the bottom end of the pipe pile.

[0028] 2.3) Pull the handle to open the ball valve so that the valve hole of the ball valve and the pipe pile are on the same axis, and then continue to press the pipe pile into the stratum below the bottom plate of the tool section;

[0029] 2.4) Place the pile driver at the tail end of the pile and continue to press it in until the height of the tail end of the pile is slightly lower than the outer bottom surface of the tool section bottom plate;

[0030] 2.5) Lift the pile driver away. When the pile driver is separated from the water stop ring, pull the handle in the opposite direction to close the ball valve.

[0031] 2.6) Move the pile driving device to the next pile hole to carry out pile driving operation.

[0032] Furthermore, a pile driver is placed at the tail end of the pipe pile. The pile driver is used to limit the driving depth of the last pipe pile in the current hole. When the pipe pile is driven to the designed depth elevation, the pile driver is pulled out and reused.

[0033] The foundation reinforcement method of the present invention is suitable for preventing uneven settlement, misalignment, and disconnection of rectangular jacking pipes in soft strata. The advantages of the present invention are:

[0034] (1) Reinforcement does not need to be carried out from the ground downwards, but rather carried out in the pipe jacking channel, effectively avoiding vertical reinforcement work from the ground that may affect road traffic, pipeline relocation, damage to buildings, and avoid river cofferdams affecting navigation;

[0035] (2) Innovatively adopting a tool section made of steel structure at the rear of the pipe jacking machine head as a piling platform. After the pipe jacking construction is completed, it can be received together with the pipe jacking machine and reused in the next project, saving construction costs.

[0036] (3) The tool section can be installed with a cylinder and can also be used as a relay room. When the resistance to long-distance jacking is large, it can be used as a relay reserve to improve the use efficiency and jacking efficiency.

[0037] (4) Pile holes are reserved on the tool section, eliminating the need to drill holes on the jacking pipe section, thus avoiding damage to the pipe section structure and affecting the quality of the tunnel / channel;

[0038] (5) A static pile device that can adapt to low headroom conditions is used to operate in a rectangular jacking tunnel. The pile lifting structure is set on the top of the tool section (with tracks and electric hoists). The static pile device is then optimized to make its structure simple and lightweight, and convenient for quick installation, disassembly and displacement. Especially in construction on soft strata, the required pile pressure is small, the construction disturbance is weak, and the efficiency is high.

[0039] (6) Green and environmentally friendly. When vertical foundation reinforcement is carried out on the ground in a busy urban area, the dust, noise and excess slurry generated have a great impact on the surrounding environment. The present invention is carried out in the jacking channel, which produces minimal disturbance. The static pressure construction is noiseless and there is no mud pollution, which meets the requirements of green environmental protection. No pile holes are opened on the bottom surface of the pipe section, which has good sealing performance and effectively avoids leakage.

[0040] (7) The economic benefits are obvious, and it does not occupy the critical construction period. It can be carried out during the installation of the pipe jacking section. No less than two machines can be used to press the piles at the same time, which is highly efficient and does not occupy the working space in the working pit, saving time, space and cost.

[0041] The present invention cleverly sets up a tool section as a pile driving platform in close proximity to the head, excavates and drives piles step by step, and then connects the pipe sections until the construction of the entire rectangular tunnel is completed; finally, the bottom surface of the pipe section and the top of the pile are repeatedly injected with curable thick clay or waterproof mortar to compact and fill gaps and stratum losses, so that the jacking pipe and the treated stratum form a whole. The entire construction process of the present invention is friendly, with small construction disturbance and high efficiency. It can adapt to soft stratum conditions and is not restricted by the ground environment; there is no need to implement vertical reinforcement of the ground to avoid affecting existing facilities; it can also maintain the structural integrity of the jacking pipe section, and it is carried out simultaneously with the rectangular jacking construction without interfering with each other. Ultimately, it can effectively prevent problems such as uneven settlement after construction, misalignment and disconnection of pipe sections, and improve the quality of jacking construction and waterproofing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 It is a schematic diagram of the construction scene of the present invention;

[0044] Figure 2 It is a schematic diagram of the pile driving process of the present invention;

[0045] Figure 3 It is a three-dimensional schematic diagram of the pile driving device in the tool section of the present invention;

[0046] Figure 4 It is a structural diagram of the tool section of the present invention;

[0047] Figure 5 Schematic diagram of the positional relationship between the pipe section and the pipe pile of the present invention;

[0048] Figure 6 yes Figure 5 Middle A-direction view;

[0049] Figure 7 It is a structural schematic diagram of the pile hole anti-seepage device of the present invention;

[0050] Figure 8 yes Figure 7 Middle B-direction view;

[0051] Figure 9 This is the working sequence of the pile driving process in the present invention Figure 1 ;

[0052] Figure 10 This is the working sequence of the pile driving process in the present invention Figure 2 ;

[0053] Figure 11 This is the working sequence of the pile driving process in the present invention Figure 3 ;

[0054] Figure 12 This is a schematic diagram of the present invention after the entire jacking channel is piled;

[0055] In the figure, 1 is the nose.

[0056] 2 is the tool section, 21 is the front section, 22 is the rear section, 221 is the pile hole, 222 is the reinforcement plate, 223 is the process steel plate,

[0057] 3 is the pipe joint, 31 is the trolley,

[0058] 4 is a pipe pile, 41 is a pile sleeve, 42 is a pile driver, 421 is a limit adjustment ring,

[0059] 5 is a pile hole anti-seepage device, 51 is a cylindrical base, 52 is a sealing bowl, 53 is a ball valve, 531 is a valve hole, 54 is a rotating pin, 55 is a handle, 56 is a threaded structure, 57 is a water-stop sleeve, 571 is a water-stop ring,

[0060] 6 is a lifting device,

[0061] 71 is the originating well, 72 is the receiving well;

[0062] 8 is thick clay,

[0063] 9 is a pile driving device, 91 is a base, 92 is a guide column, 93 is a cylinder seat, 94 is a cylinder, and 95 is a hoop. DETAILED DESCRIPTION

[0064] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0065] Among them, the drawings are only used for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0066] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inside", "outside" and the like indicate an orientation or position relationship based on the orientation or position relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0067] The present invention provides a foundation reinforcement method for rectangular pipe jacking construction under soft stratum conditions, such as Figure 1-12 As shown, a starting well 71 and a receiving well 72 are opened on the ground surface, and the head 1 of the rectangular pipe jacking machine is excavated from the starting well 71 to the receiving well 72. During the excavation process, rectangular pipe sections 3 are connected step by step to form a channel composed of several rectangular pipe sections 3. A tool section 2 is provided between the head 1 of the rectangular pipe jacking machine and the first pipe section 3, and a pile hole 221 is opened on the bottom plate of the tool section 2.

[0068] Then, the present invention is carried out according to the following steps:

[0069] 1) The machine head 1 starts to excavate from the starting well 71 and stops at the position where the foundation is to be reinforced;

[0070] 2) In the tool section 2 behind the machine head 1, use the pile driving device 9 to press the pipe piles 4 into the lower stratum, and perform the pile driving and pile delivery operations at each hole position within the current stroke until all the pipe piles 4 reach the preset depth requirements;

[0071] 3) The machine head 1 moves to the next stroke, the length of which is the same as the length of the single pipe section 3, stops moving, and repeats the pile pressing and pile delivery operations in step 2);

[0072] 4) After the excavation is completed, the tool section 2 follows the excavation section 1 into the receiving shaft 72;

[0073] 5) Pressurize the solidified thick cement 8 to the bottom surface of the pipe segment 3 multiple times to compact and fill the soil between the bottom of the pipe segment and the top of the pile;

[0074] 6) The thick glue 8 is solidified and completed.

[0075] After the above construction, the bottom of each pipe segment 3 is formed as follows: Figure 5 、 6 The pipe piles 4 are positioned in the pipe section 3. Once established, the piles 4 provide support and positioning for the subsequent advancement of the pipe section 3, effectively preventing the pipe section 3 from misaligning or becoming disjointed. Furthermore, the pipe section 3 of the present invention can be a conventional pipe section, eliminating the need for drilling pile holes in the bottom surface of the pipe section, as is currently common practice in the art. This significantly improves both strength and sealing performance.

[0076] The structure of the tool section 2 used in the present invention is further described as follows: the tool section 2 is a steel structure, and a self-propelled lifting device 6 is provided on the inner top surface of the tool section 2 for lifting the prefabricated pipe piles 4 transported from the starting well 71. The pipe piles 4 are solid piles.

[0077] The bottom surface of the tool section 2 is provided with a vertical direction of travel (such as Figure 1 、 2 The upright ribs 222 are arranged in the direction indicated by the hollow arrow, and the pile holes 221 are opened on the bottom plate between adjacent ribs 222.

[0078] The tool section 2 of the present invention adopts the structure of the front section 21 and the rear section 22 (such as Figure 4 ), the aforementioned pile hole 221 is provided on the bottom plate of the rear section 22. The structural form of the front section 21 and the rear section 22 is set, and the oil cylinder installed between the two can also be used as a relay room. When encountering a long distance jacking resistance, it can be used as a relay reserve to improve the use efficiency and jacking efficiency.

[0079] Pile pressing device 9 (such as Figure 3 ) includes a base 91, a guide post 92, a cylinder seat 93, a cylinder 94, and a clamp 95. The guide post 92 is fixedly connected to the base 91, and the cylinder seat 93 is fixed to the top of the guide post 92. The clamp 95 has clamp holes that match the pipe pile 4 and guide holes at the four corners. The clamp 95 is movably connected to the guide post 92. The piston rod of the cylinder 94 is used to push the clamp 95 downward; the clamp 95 is used to hold the pipe pile 4 and press it downward under the action of the cylinder 94. The clamp 95 is provided in two levels. The bottom clamp 95 is used to secure the pressed pipe pile 4 and expose the joint to facilitate pile connection and prevent it from tilting. The upper clamp 95 is used to hold the pipe pile 4 to be pressed downward under the action of the cylinder 94. The clamp 95 is fixed hydraulically.

[0080] Working mechanism of the pile driving device 9: The prefabricated pile is pressed into the soil by utilizing the static pressure generated by the deadweight and counterweight of the pile driving device 9, and the pile is sunk by overcoming the friction resistance on the pile side and the resistance at the pile end. The static pressure required in soft strata is relatively small, so two oil cylinders 94 can be provided for pile driving, and the static pressure is determined by calculating the specific stratum conditions. The prefabricated pipe pile 4 is held by a clamp 95, and the clamp 95 is driven downward by the telescopic oil cylinder 94 to achieve pile driving. After one advance is made, the oil cylinder 94 is retracted to drive the clamp upward, and then the next advance is made. After the first pile is driven, a joint part is reserved, and after connecting it to the pile to be driven by the pile sleeve 41, the above pile driving action is repeated.

[0081] The base of the pile driving device 9 is provided with a pile driver track to facilitate the displacement of the pile driving device. An anchoring device that is easy to disassemble is also provided to facilitate the stability of the entire device during pile driving. The pile driver track does not affect the internal operation of the rectangular jacking pipe.

[0082] In order to facilitate the lifting of the pipe pile 4, a self-propelled lifting device 6 is provided on the top of the tool section 2. Tracks should be set in the vertical and horizontal directions to correspond to the track positions used by the pile driving device 9, which is conducive to the lifting operations when driving and connecting piles.

[0083] To address the technical challenge of water seepage during construction, the present invention provides a pile hole anti-seepage device 5 on each pile hole 221. The pile hole anti-seepage device 5 comprises a cylindrical base 51, a sealing bowl 52, a ball valve 53, and a handle 55. The ball valve 53 has a center hole (i.e., a valve hole 531) adapted to the outer diameter of the pipe pile 4, for the pipe pile 4 to pass freely under driving. The ball valve 53 is movably connected to the cylindrical base 51 via a rotation pin 54. The handle 55 is used to control the reciprocating rotation of the ball valve 53 within a range of 90 degrees.

[0084] The sealing bowl 52 is made of elastic material and is fixedly arranged on the inner wall of the cylindrical base 51. The sealing bowl 52 has an inner spherical surface that matches the spherical surface of the ball valve 53. Figure 7 State, sealing is achieved.

[0085] The tubular base 51 also includes a water-stop sleeve 57, which is detachably connected to the top of the tubular base 51 via a threaded structure 56. The inner tube of the water-stop sleeve 57 is equipped with at least two elastic water-stop rings 571, each with an inner diameter smaller than the outer diameter of the tubular pile 4. The water-stop sleeve 57 can be removed and reused in the next hole driving operation, facilitating replacement and maintenance.

[0086] A protrusion structure is provided on the outer surface of the water-stop sleeve 57 to facilitate the rotation operation.

[0087] like Figure 9-11 , Step 2) Medium pressure pile operation is as follows:

[0088] 2.1) Lay a process steel plate 223 on the top surface of the rib plate 222 outside the pile hole anti-seepage device 5, and place the pile driving device 9 on the process steel plate 223;

[0089] 2.2) Lift the pile 4 to the top of the pile hole anti-seepage device 5 using the lifting device 6, and align the pile 4 with the top of the water-stop sleeve 57. Use the pile 4's own weight or the pile-pressing device 9 to press the pile 4 down a certain distance until the elastic water-stop ring 571 covers the bottom of the pile 4.

[0090] 2.3) Pull the handle 55 to open the ball valve 53, so that the valve hole 531 of the ball valve 53 is on the same axis as the pipe pile 4. Then continue to press the pipe pile 4 into the stratum below the bottom plate of the tool section. If the pipe pile 4 is not long enough, you can connect the pipe piles through the pile sleeve 41.

[0091] 2.4) Place the pile driver 42 at the tail end of the pile 4 and continue to press it in until the tail end of the pile 4 is slightly lower than the outer bottom surface of the bottom plate of the tool section 2;

[0092] 2.5) Lift the pile driver 42 away. When the pile driver 42 is separated from the water stop ring 571, pull the handle 55 in the opposite direction to close the ball valve 53.

[0093] 2.6) Shift the pile driving device 9 to the next pile driving hole 221 to perform pile driving operation.

[0094] A pile driver 42 is placed at the tail end of the pile 4. The pile driver 42 is used to limit the driving depth of the last pile 4 in the current hole. When the pile 4 is driven to the designed depth, the pile driver 42 is pulled out and reused. A limit adjustment ring 421 can be set on the upper part of the pile driver 42 to adjust the driving depth according to different scenarios.

[0095] This invention breaks with conventional thinking in the field and solves the challenges of underground tunnel construction in soft strata and areas rich in groundwater. This innovative construction method, which involves first laying and driving piles, then installing pipe segments, completely avoids uneven settlement, misalignment, or disconnection of pipe segments. This results in high overall strength and waterproofing for the pipe-jacking tunnel / passage.

[0096] It should be noted that the above-described specific embodiments are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that, based on the technical content disclosed in this application, various modifications, equivalent substitutions, and variations may be made to the present invention. However, as long as these modifications do not depart from the spirit of the present invention, they are intended to be within the scope of protection of the present invention. Furthermore, certain terms used in the specification and claims of this application are not intended to be limiting and are provided solely for ease of description.

Claims

1. A foundation reinforcement method using rectangular pipe jacking in soft ground conditions, wherein a starting well and a receiving well are opened on the ground surface, and a rectangular pipe jacking machine is driven from the starting well to the receiving well. During the driving process, rectangular pipe sections are connected step by step to form a channel composed of several rectangular pipe sections. The method is characterized in that: A tool section is provided between the rectangular pipe jacking machine head and the first pipe section, and a pile pressing hole is provided on the bottom plate of the tool section; Then, follow these steps: 1) The machine head starts to excavate from the starting well and stops at the location where the foundation is to be reinforced; 2) In the tool section behind the machine head, use the pile driving device to press the pipe piles into the lower stratum, and perform the pile driving and pile delivery operations for each hole position within the current stroke until all the pipe piles reach the preset depth requirements; 3) The machine head moves to the next stroke, the length of which is the same as the length of the single pipe section, stops and repeats the pile pressing and pile delivery operations in step 2); 4) After the excavation is completed, the tool section enters the receiving well along with the excavator head; 5) Pressurize the bottom surface of the pipe section with curable thick clay several times to compact and fill the soil between the bottom of the pipe section and the top of the pile; 6) The thick clay solidifies and is completed; The tool section is a steel structure, and a self-propelled hoisting device is provided on the inner top surface of the tool section for hoisting the prefabricated pipe piles transported from the starting well. The pipe piles are solid piles. The bottom surface of the tool section is provided with upright ribs perpendicular to the travel direction, and the pile-pressing holes are opened on the bottom plate between adjacent ribs; The pile driving device includes a base, a guide column, a cylinder seat, a cylinder and a hoop. The guide column is fixedly connected to the base, the cylinder seat is fixedly arranged on the top of the guide column, the hoop is provided with a hoop hole matching the pipe pile and guide holes arranged at four corners, the hoop is movably connected to the guide column, and the piston rod of the cylinder is used to push the hoop downward; two hoop are provided, the bottom hoop is used to fix the pressed pipe pile and expose the joint for convenient pile connection and prevent it from tilting, and the upper hoop is used to hold the pipe pile to be pressed and press the pile downward under the action of the cylinder; the hoop is fixed in a hydraulic form.

2. The foundation reinforcement method of rectangular pipe jacking construction under soft stratum conditions according to claim 1 is characterized in that: A pile driver track is provided on the base of the pile driving device to facilitate the displacement of the pile driving device; an easily disassembled anchoring device is also provided to facilitate the stability of the entire device during pile driving; the pile driver track does not affect the internal operation of the rectangular jacking pipe.

3. The foundation reinforcement method of rectangular pipe jacking construction under soft stratum conditions according to claim 1 is characterized in that: A self-propelled lifting device is provided on the top of the tool section, and tracks should be set in the vertical and horizontal directions, corresponding to the track positions used by the pile driving device, to facilitate the lifting operations during pile driving and pile connection.

4. The foundation reinforcement method of rectangular pipe jacking construction under soft stratum conditions according to claim 1 is characterized in that: A pile hole anti-seepage device is provided on each of the pile holes, comprising a cylindrical base, a sealing bowl, a ball valve and a handle; the ball valve has a center hole adapted to the outer diameter of the pile, the ball valve is movably connected to the cylindrical base via a rotation pin, and the handle is used to control the reciprocating rotation of the ball valve; The sealing bowl is made of elastic material and is fixedly arranged on the inner wall of the cylindrical base. The sealing bowl has an inner spherical surface adapted to the spherical surface of the ball valve for achieving sealing.

5. The foundation reinforcement method of rectangular pipe jacking construction under soft stratum conditions according to claim 4 is characterized in that: It also includes a water-stop sleeve detachably connected to the top of the cylindrical base through a threaded structure, and the inner tube of the water-stop sleeve is provided with at least two elastic water-stop rings with an inner diameter smaller than the outer diameter of the pipe pile.

6. The foundation reinforcement method of rectangular pipe jacking construction under soft stratum conditions according to claim 5 is characterized in that: A protruding structure is provided on the outer surface of the water-stop sleeve to facilitate the rotation operation.

7. The foundation reinforcement method of rectangular pipe jacking construction under soft stratum conditions according to claim 6 is characterized in that: The step 2) of medium pressure pile operation is specifically as follows: 2.1) Laying a process steel plate on the top surface of the rib plate outside the pile hole anti-seepage device, and placing the pile driving device on the process steel plate; 2.2) Lift the pipe pile to the top of the pile hole anti-seepage device and align the pipe pile with the top of the water-stop sleeve. Use the pile's own weight or the pile-pressing device to press the pile down for a certain distance until the elastic water-stop ring covers the bottom end of the pipe pile. 2.3) Pull the handle to open the ball valve so that the valve hole of the ball valve and the pipe pile are on the same axis, and then continue to press the pipe pile into the stratum below the bottom plate of the tool section; 2.4) Place the pile driver at the tail end of the pile and continue to press it in until the height of the tail end of the pile is slightly lower than the outer bottom surface of the tool section bottom plate; 2.5) Lift the pile driver away. When the pile driver is separated from the water stop ring, pull the handle in the opposite direction to close the ball valve. 2.6) Move the pile driving device to the next pile hole to carry out pile driving operation.

8. The foundation reinforcement method of rectangular pipe jacking construction under soft ground conditions according to claim 7 is characterized in that: A pile driver is placed at the tail end of the pipe pile. The pile driver is used to limit the driving depth of the last pipe pile in the current hole. When the pipe pile is driven to the designed depth elevation, the pile driver is pulled out and reused.

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