High strain detection device for horizontal bearing capacity of pile foundation

Abstract

The invention discloses a high-strain detection device for horizontal bearing capacity of a pile foundation. The high-strain detection device comprises a carbon dioxide phase change pulse device, a pulse transmission device, a counter-force device, a pile foundation detection assembly and a base, the counter-force device and the pulse transmission device are arranged at the two ends of the carbon dioxide phase change pulse device respectively, the pulse transmission device is installed on a test pile, the carbon dioxide phase change pulse device applies horizontal pulses to the test pile through the pulse transmission device, and the pile foundation detection assembly is arranged on the test pile and the pulse transmission device. The base is arranged on the ground and used for fixing the counter-force device. The device utilizes carbon dioxide phase change to release energy to generate impact force which acts on a test pile, and can carry out horizontal bearing capacity test on a large-diameter pile foundation without the help of a large number of anchor piles and counter-force devices, so that the construction period is greatly shortened, the cost is saved, and the efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of pile foundation high strain detection, and in particular to a pile foundation horizontal bearing capacity high strain detection device. Background Art

[0002] As a traditional compression-resistant component with good performance, the vertical bearing capacity of pile foundation is fully utilized, which can meet most engineering needs and is widely used in land engineering and marine engineering. In the process of island and reef and coastal offshore construction, pile foundation is one of the most common upper building (structure) support structures, among which the proportion of single pile foundation in shallow water areas of European coastline is as high as 87%. In addition to bearing the vertical loads imposed by the upper structure, it is also subjected to horizontal loads such as wind loads, wave loads, water flow loads, and ship impact loads for a long time, which is prone to large deflection angles and horizontal deformations. However, when designing pile foundations, the damage and destruction caused by horizontal loads to pile foundations are usually underestimated, resulting in frequent accidents of marine engineering facilities. In order to ensure the safe use of marine engineering facilities, it is necessary to carry out on-site horizontal bearing capacity testing to provide a basis for the horizontal bearing capacity design of pile foundations.

[0003] At present, the horizontal bearing capacity test of pile foundation mainly adopts the static maintenance loading method, which requires driving multiple reaction anchor piles around the pile to be tested, and providing horizontal load to the test pile by installing the reaction device, and maintaining it for a long time to observe the horizontal displacement of the test pile. This traditional method is stable and reliable, but it also has obvious limitations. For offshore projects with a short window period, the static maintenance loading method has a long detection cycle, and the transportation cost and time cost required for detection are very high. At the same time, with the development of marine engineering construction, the diameter of the pile foundation continues to increase, the reaction force required for bearing capacity detection has increased exponentially, and the size of the anchor pile must also increase accordingly. For different test piles, it is also necessary to rebuild the reaction device, which undoubtedly greatly increases the cost of making and installing the reaction anchor pile and the reaction device. In addition, the position of the traditional static maintenance loading method when applying the horizontal load usually depends on the height of the reaction anchor pile and the reaction device, and the action point of horizontal loads such as wind force and wave flow is not single, so the test results are difficult to reflect the actual situation. Compared with the entire pile surface area, the contact surface where the load is applied can be regarded as a point load rather than a surface load, which can easily cause excessive local pressure, resulting in damage or even breakage of the free end of the pile foundation. Summary of the invention

[0004] Purpose of the invention: In order to overcome the shortcomings of the background technology, the present invention discloses a high-strain detection device for the horizontal bearing capacity of a pile foundation. The device is based on carbon dioxide phase change pulse technology, generates horizontal air pressure shock waves through an electric excitation device, collects the dynamic response of the pile body under impact load, and determines the horizontal bearing capacity of the pile foundation.

[0005] Technical solution: The high-strain detection device for the horizontal bearing capacity of a pile foundation disclosed in the present invention comprises a carbon dioxide phase change pulse device, a pulse transmission device, a reaction force device, a pile foundation detection component and a base; the reaction force device and the pulse transmission device are respectively arranged at both ends of the carbon dioxide phase change pulse device, the pulse transmission device is installed on the test pile, the carbon dioxide phase change pulse device applies a horizontal pulse to the test pile through the pulse transmission device, the pile foundation detection component is arranged on the test pile and the pulse transmission device, and the base is placed on the ground for fixing the reaction force device.

[0006] Furthermore, the carbon dioxide phase change pulse device includes a reaction tank, one end of which is provided with an energy release head, the energy release head includes a constant pressure energy release sheet and an explosion release nozzle, the explosion release nozzle is fastened to the reaction thread, the constant pressure energy release sheet is fixed to the energy release end of the reaction tank, and is connected to the pulse transmission device through the energy release end; the other end of the reaction tank is provided with a fastener, an inner chamber is formed inside the reaction tank, the inner chamber is filled with supercritical carbon dioxide and a carbon dioxide energy-gathering agent, and the end of the fastener in the reaction tank is connected to the end of the reaction force device.

[0007] Furthermore, the fastener includes a sealing plug and a cap arranged from the inside to the outside at the end of the reaction tank, a heater is provided at the inner center of the sealing plug, and the lead of the heater passes through the seal and the cap and leads out, including a heater trigger line and a carbon dioxide energy agent excitation line.

[0008] Furthermore, the pulse transmission device includes a retractable gun barrel and an impact protection cover, one end of the retractable gun barrel is connected to the energy dissipation end of the carbon dioxide phase change pulse device, the impact protection cover includes an upper end face, a lower hole and a side hole, the other end of the retractable gun barrel is connected to the side hole, the upper end face is provided with a lifting ring for lifting, and the lower hole is mounted on the top of the test pile.

[0009] Furthermore, the pile foundation detection assembly includes strain gauges symmetrically arranged on the test pile, an inclination sensor arranged at the center of the test pile, and a displacement sensor, a force sensor, and an acceleration sensor symmetrically arranged at the side holes of the impact protection cover.

[0010] Furthermore, the reaction force device includes an annular limit device, a side wall of one end of the annular limit device is provided with a reserved hole, the reaction tank is inserted through this end, and the lead is led out from the reserved hole, and the other end of the interior of the annular limit device is provided with an oil cylinder, a piston and a rubber buffer layer in sequence, the oil cylinder is filled with hydraulic oil, the piston includes piston heads on both sides and a piston rod in the middle, and a plurality of reserved grooves are arranged at intervals on the outer piston head, and a piston ring is arranged in the reserved groove, and the annular limit device is provided with an annular protrusion for limiting the movement of the rubber buffer layer at a position close to the reserved hole, thereby forming an axial limit for the rubber buffer layer.

[0011] Furthermore, a damping cushion and a tail latch are provided at the outer end of the annular limiting device on one side of the oil cylinder, and a latch hole is provided at the pin head of the tail latch.

[0012] Furthermore, the base includes a head connecting pin seat and a tail connecting pin, the head connecting pin seat includes a vertical block for the annular limiting device to pass through and a first bottom plate with a circular hole for the pin, the first bottom plate is fixed to the ground by a first connecting nut and a first connecting screw, the tail connecting pin seat includes two vertical plates arranged at intervals and a second bottom plate with a circular hole for the pin, the vertical plates are fixed to the second bottom plate by lateral supports, the pin head is placed between the two vertical plates, and the connection is achieved by a pin shaft passing through the vertical plates and the pin head, and the second bottom plate is fixed to the ground by a second connecting nut and a second connecting screw.

[0013] Beneficial effects: Compared with the prior art, the advantages of the present invention are: 1. The carbon dioxide phase change releases energy to generate impact force and acts on the test pile. It does not require a large number of anchor piles and reaction devices to carry out horizontal bearing capacity tests on large-diameter pile foundations, which greatly shortens the construction period, saves costs, and improves efficiency. The various parts of the device are detachable, easy to assemble, and simple to operate. It can be flexibly applied to multiple scenarios and working conditions, and can meet the needs of applying horizontal load forces at different points. By replacing the carbon dioxide phase change pulse device, it can be quickly and conveniently reused; 2. In order to prevent gas leakage, the lead side of the carbon dioxide phase change pulse device is double-fastened and sealed by a sealing plug and a cap, and the gas outlet side is tightened by the thread of the explosion relief nozzle to fix the pressure relief sheet. The thermal excitation device and the carbon dioxide energy-gathering agent excitation line are built into the sealing plug in advance, which greatly improves the stability of the impact gas pressure; 3. The reaction force device uses rubber cushion, piston, hydraulic fluid and damping cushion for quadruple buffering, which effectively absorbs and dissipates the impact reaction force applied by the carbon dioxide phase change pulse device, thus improving the safety of the test; 4. The piston head is embedded with a piston ring, which will deform and shrink under stress, thereby pushing the piston rod to move, further squeezing the hydraulic fluid and providing hydraulic dissipation reaction force. At the same time, the piston ring can also effectively reduce the possibility of hydraulic fluid leakage, and can scrape off excess hydraulic fluid on the inner chamber wall during reciprocating motion; 5. The use of green and environmentally friendly inert gas carbon dioxide as the shock source replaces the traditional diesel and gasoline-driven power systems, reduces environmental pollution, and promotes the recycling of carbon dioxide, which helps to achieve the goals of carbon peak and carbon neutrality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 This is a split structure diagram of the carbon dioxide phase change pulse device of the present invention; Figure 3 It is a cross-sectional view of the carbon dioxide phase change pulse device of the present invention; Figure 4 It is a schematic diagram of the structure of the pulse transmission device of the present invention; Figure 5 It is a schematic diagram of the external structure of the reaction force device of the present invention; Figure 6 is an internal cross-sectional view of the reaction force device of the present invention; Figure 7 It is a schematic diagram of the piston structure of the present invention; Figure 8 This is a schematic diagram of the head connecting pin seat structure of the present invention; Fig. 9 It is a schematic diagram of the tail connecting pin seat structure of the present invention. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0016] like Figure 1-9 The pile foundation horizontal bearing capacity high-strain detection device shown includes a carbon dioxide phase change pulse device 1, a pulse transmission device 2, a reaction force device 3, a pile foundation detection component 4 and a base 5; the reaction force device 3 and the pulse transmission device 2 are respectively arranged at the two ends of the carbon dioxide phase change pulse device 1, the pulse transmission device 2 is installed on the test pile, the carbon dioxide phase change pulse device 1 applies horizontal pulses to the test pile through the pulse transmission device 2, the pile foundation detection component 4 is arranged on the test pile and the pulse transmission device 2, and the base 5 is placed on the ground for fixing the reaction force device 3.

[0017] The carbon dioxide phase change pulse device 1 includes a reaction tank 11, one end of which is provided with an energy release head 13, the energy release head 13 includes a constant pressure energy release sheet 132 and an explosion release nozzle 131, the explosion release nozzle 131 is threadedly fastened to the reaction tank 11, the constant pressure energy release sheet 132 is fixed to the energy release end of the reaction tank 11, and is connected to the pulse transmission device 2 through the energy release end; the other end of the reaction tank 11 is provided with a fastener 14, an inner chamber 12 is formed inside the reaction tank 11, the inner chamber 12 is filled with supercritical carbon dioxide 121 and a carbon dioxide energy gathering agent 122, and the end of the fastener 14 in the reaction tank 11 is connected to the end of the reaction force device 3.

[0018] The fastener 14 includes a sealing plug 142 and a cap 143 arranged from the inside to the outside at the end of the reaction tank 11. A heater 141 is provided at the inner center of the sealing plug 142. The lead 144 of the heater 141 passes through the sealing plug 142 and the cap 143 and leads out, including a heater trigger line 1441 and a carbon dioxide energy agent excitation line 1442.

[0019] The pulse transmission device 2 includes a telescopic barrel 21 and an impact protection cover 22. One end of the telescopic barrel 21 is connected to the energy dissipation end of the carbon dioxide phase change pulse device 1. The impact protection cover 22 includes an upper end surface 221, a lower hole 222 and a side hole 223. The other end of the telescopic barrel 21 is connected to the side hole 223. The upper end surface 221 is provided with a lifting ring 2211 for lifting. The lower hole 222 is mounted on the top of the test pile.

[0020] The pile foundation detection assembly 4 includes strain gauges 41 symmetrically arranged on the test pile, a tilt sensor 42 arranged at the center of the test pile, and a displacement sensor 43, a force sensor 44, and an acceleration sensor 45 symmetrically arranged on the side holes 223 of the impact protection cover 21.

[0021] The reaction force device 3 includes an annular limiting device 31, and a side wall at one end of the annular limiting device 31 is provided with a reserved hole 311, the reaction tank 11 is inserted from this end, and the lead 144 is led out from the reserved hole 311. The other end of the annular limiting device 31 is provided with an oil cylinder 34, a piston 33 and a rubber buffer layer 32 in sequence, and the oil cylinder 34 is filled with hydraulic oil 341. The piston 33 includes piston heads 331 on both sides and a piston rod 332 in the middle. A plurality of reserved grooves 3311 are arranged at intervals on the outer piston head 331, and a piston ring 3312 is arranged in the reserved groove 3311. The annular limiting device 31 is provided with an annular protrusion for limiting the movement of the rubber buffer layer 32 near the reserved hole 311, so as to form an axial limit for the rubber buffer layer 32.

[0022] The outer end of the annular limiting device 31 located on one side of the oil cylinder 34 is provided with a damping cushion 36 and a tail latch 35 , and a latch hole is provided at the pin head 351 of the tail latch 35 .

[0023] The base 5 includes a head connecting pin seat 51 and a tail connecting pin seat 52. The head connecting pin seat 51 includes a vertical block 511 for the annular limiting device 31 to pass through and a first bottom plate 512 with a circular hole for a pin. The first bottom plate 512 is fixed to the ground by a first connecting nut 5121 and a first connecting screw 5122. The tail connecting pin seat 52 includes two vertical plates 521 arranged at intervals and a second bottom plate 523 with a circular hole for a pin. The vertical plates 521 are fixed to the second bottom plate 523 by a lateral support 522. The pin head 351 is placed between the two vertical plates 521 and is connected by a pin shaft 352 passing through the vertical plates 521 and the pin head 351. The second bottom plate 523 is fixed to the ground by a second connecting nut 5231 and a second connecting screw 5232.

[0024] The construction and use of this device include the following steps: (1) Test pile preparation: High strain detection sensors, including displacement sensors 43, force sensors 44 and acceleration sensors 45, are installed in the symmetrical direction of the side holes 223 of the impact protection cover 22. Pile body strain gauges 41 are pasted at a certain interval below them, and an inclination sensor 42 is installed at the center line position along the horizontal loading direction.

[0025] (2) Selection and assembly of horizontal impact device: According to the conversion relationship between the energy released by the phase change of critical carbon dioxide and the TNT equivalent, the strength and thickness of the constant pressure energy release sheet 132 are determined. The constant pressure energy release sheet 132 is placed at the outlet of the inner chamber and fixed by screwing with the explosion relief nozzle 131. The sealing plug 142 is inserted into the inner chamber 12 from the tail, and then the cap 143 is installed by threading to form a fastener 14. The initial heat is provided by the carbon dioxide energy-gathering agent excitation line 1442 to allow the carbon dioxide energy-gathering agent 122 to burn rapidly, and then the heater trigger line 1441 is used to heat the supercritical carbon dioxide 121 in the inner chamber 12. Under the action of the carbon dioxide energy-gathering agent 122, a large amount of carbon dioxide gas is produced, forming a huge pressure in the enclosed space, and then reaching the rated pressure value of the constant pressure energy release sheet 132, and finally generating a shock wave.

[0026] (3) Selection and installation of reaction device: Determine the position of the head connecting pin seat 51 and the tail connecting pin seat 52 according to the position of the side hole 223, and then connect and fix them to the ground. Fill the oil cylinder 34 with hydraulic fluid 341, fix the piston 33 behind the annular limit device 31 and the rubber buffer layer 32, and make close contact when the hydraulic fluid 341 is balanced.

[0027] (4) Assembly of the pulse transmission device: Place the impact protection cover 22 on the top of the test pile, then place one side of the fastener 14 of the carbon dioxide phase change pulse device 1 into the reaction device 3, lead the heater trigger line 1441 and the carbon dioxide energy gathering agent excitation line 1442 out from the reserved hole 311 on the annular limit device 31, and connect one side of the energy release head 13 to the side hole 223 through the retractable gun barrel 21.

[0028] (5) Horizontal bearing capacity high strain detection: After the various parts of the pile foundation horizontal bearing capacity high strain detection device are assembled, the heater trigger line 1441 is energized until the constant pressure energy release plate 132 breaks and generates a horizontal shock wave acting on the top of the test pile. The pile foundation detection component 4 is connected to the dynamic data acquisition instrument through a data transmission line. After setting the channel parameters, the balance cleaning starts to collect the signals detected by the sensor and transmits them to the data processing system for processing and analysis. After the impact is completed, the reaction device needs to disassemble the screw, take out the consumed carbon dioxide phase change pulse device, install a new carbon dioxide phase change pulse device, and then readjust the position for the next horizontal impact.

Claims

1. A pile foundation horizontal bearing capacity high strain detection device, characterized in that: The invention comprises a carbon dioxide phase change pulse device (1), a pulse transmission device (2), a reaction force device (3), a pile foundation detection component (4) and a base (5); the reaction force device (3) and the pulse transmission device (2) are respectively arranged at two ends of the carbon dioxide phase change pulse device (1); the pulse transmission device (2) is installed on a test pile; the carbon dioxide phase change pulse device (1) applies a horizontal pulse to the test pile through the pulse transmission device (2); the pile foundation detection component (4) is arranged on the test pile and the pulse transmission device (2); and the base (5) is placed on the ground and is used to fix the reaction force device (3).

2. The pile foundation horizontal bearing capacity high strain detection device according to claim 1, characterized in that: The carbon dioxide phase change pulse device (1) comprises a reaction tank (11); one end of the reaction tank (11) is provided with an energy release head (13); the energy release head (13) comprises a constant pressure energy release sheet (132) and an explosion release nozzle (131); the explosion release nozzle (131) is threadedly fastened to the reaction tank (11); the constant pressure energy release sheet (132) is fixed to the energy release end of the reaction tank (11); and the energy release end is connected to the pulse transmission device (2); the other end of the reaction tank (11) is provided with a fastener (14); an inner chamber (12) is formed inside the reaction tank (11); the inner chamber (12) is filled with supercritical carbon dioxide (121) and a carbon dioxide energy gathering agent (122); and the end of the reaction tank (11) where the fastener (14) is located is connected to the end of a reaction force device (3).

3. The pile foundation horizontal bearing capacity high strain detection device according to claim 2, characterized in that: The fastener (14) comprises a sealing plug (142) and a cover cap (143) arranged from the inside to the outside at the end of the reaction tank (11); a heater (141) is provided at the inner center of the sealing plug (142); a lead wire (144) of the heater (141) passes through the sealing plug (142) and the cover cap (143) and leads out, and comprises a heater trigger wire (1441) and a carbon dioxide energy agent excitation wire (1442).

4. The pile foundation horizontal bearing capacity high strain detection device according to claim 1, characterized in that: The pulse transmission device (2) comprises a telescopic gun tube (21) and an impact protection cover (22); one end of the telescopic gun tube (21) is connected to the energy dissipation end of the carbon dioxide phase change pulse device (1); the impact protection cover (22) comprises an upper end surface (221), a lower hole (222) and a side hole (223); the other end of the telescopic gun tube (21) is butt-jointed with the side hole (223); the upper end surface (221) is provided with a lifting ring (2211) for lifting; and the lower hole (222) is sleeved on the top of a test pile.

5. The pile foundation horizontal bearing capacity high strain detection device according to claim 4, characterized in that: The pile foundation detection component (4) comprises strain gauges (41) symmetrically arranged at intervals on the test pile, an inclination sensor (42) arranged at the center of the test pile, and a displacement sensor (43), a force sensor (44), and an acceleration sensor (45) symmetrically arranged at the side holes (223) on the impact protection cover (21).

6. The pile foundation horizontal bearing capacity high strain detection device according to claim 3, characterized in that: The reaction force device (3) comprises an annular limiting device (31). A reserved hole (311) is provided on a side wall of one end of the annular limiting device (31). The reaction tank (11) is inserted through the end, and the lead wire (144) is led out through the reserved hole (311). The other end of the annular limiting device (31) is provided with an oil cylinder (34), a piston (33) and a rubber buffer layer (32) in sequence. The oil cylinder (34) is filled with hydraulic oil (341). The piston (33) comprises piston heads (331) on both sides and a piston rod (332) in the middle. A plurality of reserved grooves (3311) are provided at intervals on the piston head (331) located on the outside. A piston ring (3312) is provided in the reserved groove (3311). The annular limiting device (31) is provided with an annular protrusion for limiting the movement of the rubber buffer layer (32) at a position close to the reserved hole (311), thereby forming an axial limit for the rubber buffer layer (32).

7. The pile foundation horizontal bearing capacity high strain detection device according to claim 6, characterized in that: The outer end of the annular limiting device (31) located on one side of the oil cylinder (34) is provided with a damping cushion (36) and a tail latch (35), and a latch hole is provided at the pin head (351) of the tail latch (35).

8. The pile foundation horizontal bearing capacity high strain detection device according to claim 7, characterized in that: The base (5) comprises a head connecting pin seat (51) and a tail connecting pin seat (52); the head connecting pin seat (51) comprises a vertical block (511) for the annular limiting device (31) to pass through and a first bottom plate (512) with a pin hole; the first bottom plate (512) is fixed to the ground via a first connecting nut (5121) and a first connecting screw (5122); the tail connecting pin seat (52) comprises two vertical plates (521) arranged at intervals and a second bottom plate (523) with a pin hole; the vertical plates (521) are fixed to the second bottom plate (523) via a transverse support (522); the pin head (351) is placed between the two vertical plates (521) and connected via a pin shaft (352) passing through the vertical plates (521) and the pin head (351); the second bottom plate (523) is fixed to the ground via a second connecting nut (5231) and a second connecting screw (5232).

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