An intelligent measurement system and test method for cast-in-place pile deformation and steel cage length

Abstract

The present invention belongs to the field of pile foundation monitoring and detection technology, and in particular, relates to an intelligent measurement system and test method for deformation of bored piles and steel cage length, wherein the intelligent coated steel bar comprises a CFRP bar, the end face of the CFRP bar is provided with a through hole, the central axis of the through hole is parallel to the central axis of the CFRP bar, and the outer side of the CFRP bar is covered with a stainless steel coating. The present invention provides an intelligent measurement system and test method for deformation of bored piles and steel cage length based on intelligent coated steel bar technology, which can measure the horizontal displacement of bored pile body and steel cage length, and can realize online monitoring of bored pile construction quality and foundation pit construction safety.

Description

Technical Field

[0001] The invention belongs to the technical field of pile foundation monitoring and detection, and in particular relates to an intelligent measurement system and a test method for cast-in-place pile deformation and steel cage length. Background Art

[0002] Existing technology:

[0003] Bored cast-in-place pile row support is the most commonly used support method in deep foundation pit support projects. During on-site construction, mechanical holes are used to place steel cages in the holes and concrete is poured. In order to control the construction quality, it is necessary to conduct random inspections on the length of the foundation pile steel cages after the construction of the cast-in-place piles is completed. The commonly used detection technology is the magnetic logging method, which requires drilling holes in the pile body or the side of the pile, and using professional instruments to test the magnetic changes to analyze and determine the buried depth of the steel cage. However, this method involves the entry and exit of drilling equipment, the operation process is cumbersome and will also partially damage the cast-in-place piles. For foundation pit support projects, it may cause external moisture to penetrate into the foundation pit. In addition, during the excavation of the foundation pit, due to the active earth pressure of the rock and soil body and the influence of the construction load around the foundation pit, the bored cast-in-place piles will inevitably produce a certain horizontal displacement into the pit. If the horizontal displacement exceeds a certain limit, the support piles will become unstable and the foundation pit will collapse, which may cause major casualties and property losses.

[0004] At present, the commonly used horizontal displacement monitoring technology is to bury the inclinometer tube before the concrete pouring of bored piles. After the piles are formed, the inclinometer tube and the bored piles are deformed together, and the horizontal displacement is calculated by measuring the angle change of each section of the inclinometer tube. However, there are certain disadvantages in using this method. The stiffness of the inclinometer tube is different from that of the concrete of the bored piles, resulting in inconsistent deformation of the two. The inclinometer tube is connected by multiple sections of PVC pipes, and the joint position may be dislocated due to the horizontal displacement of the soil, resulting in the inclinometer probe being unable to be lowered. The inclinometer tube is pre-buried, and after the bored piles are completed, the pile head needs to be broken within 0.5 to 1.0 m of the pile top. If an automated online monitoring inclinometer is used, the measuring line will inevitably be destroyed. If conventional manual measurement is used, the deformation of the foundation pit cannot be monitored in real time, and it is difficult to play a good auxiliary decision-making role in construction.

[0005] Prior to the present invention, an invention patent (publication number: CN 112388990 A) disclosed an intelligent carbon fiber rib with embedded optical fiber and a method for making the same. The method implants optical fiber as a sensing material inside the intelligent carbon fiber rib, and uses carbon fiber as a reinforcement body, which is impregnated with resin and then pultruded and wound into an integrated form, and has the functions of both structural reinforcement and service performance monitoring. The intelligent carbon fiber rib can be used to replace a single steel bar at a specific position of a steel cage to achieve intelligent monitoring of horizontal displacement. However, the curing temperature of the resin is generally around 200°C, which exceeds the tolerance temperature of the external polymer coating of the optical fiber sensor and the depth-measuring resistance wire, making it difficult to achieve the encapsulation of the above-mentioned intelligent monitoring cable. In addition, when using carbon fiber ribs as intelligent monitoring ribs for cast-in-place pile steel cages, it is difficult to ensure the integrity of the optical fiber when the steel bars at both ends are hot-melt welded.

[0006] The difficulty and significance of solving the above technical problems:

[0007] Therefore, based on these problems, it is of great practical significance to provide an intelligent measurement system and test method for bored pile deformation and steel cage length based on intelligent covering steel bar technology, which can measure the horizontal displacement of bored pile body and steel cage length, and realize online monitoring of bored pile construction quality and foundation pit construction safety. Summary of the invention

[0008] The purpose of this application is to solve the technical problems in the prior art and to provide a system and a test method for measuring the horizontal displacement of the bored cast-in-place pile body and the length of the steel cage based on the intelligent covering steel bar technology, so as to realize online monitoring of the bored cast-in-place pile construction quality and foundation pit construction safety.

[0009] The technical solution adopted by the embodiment of the present application to solve the technical problems existing in the known technology is:

[0010] A smart coated steel bar comprises a CFRP bar, an end surface of the CFRP bar is provided with a through hole, a central axis of the through hole is parallel to the central axis of the CFRP bar, and the outer side of the CFRP bar is covered by a stainless steel coating.

[0011] The embodiments of the present application may also adopt the following technical solutions:

[0012] In the above-mentioned intelligent coated steel bar, further, the number of the through holes is two, which are recorded as a fiber grating reserved hole and an enameled metal wire reserved hole.

[0013] In the above-mentioned intelligent covered steel bar, further, a high-strength fastener bolt is provided at one end of the through hole, and the high-strength fastener bolt includes a screw and a nut, the middle of the screw is a hollow inner hole, and a side hole is opened on the side of the screw below the nut, and the side hole is connected to the inner hole; a rubber plug is inserted into the through hole, and a hole is provided in the center of the rubber plug.

[0014] A cast-in-place pile deformation and steel cage length intelligent measurement system, the cast-in-place pile deformation and steel cage length intelligent measurement system comprises the above-mentioned intelligent coated steel bar, the intelligent coated steel bar replaces at least one conventional steel bar on the steel cage.

[0015] In the above-mentioned intelligent measurement system for cast-in-place pile deformation and steel cage length, further, the two intelligent coated steel bars are connected by a sleeve.

[0016] In the above-mentioned intelligent measurement system for cast-in-place pile deformation and steel cage length, further, a distributed fiber grating and / or enameled metal wire passes through the through hole, one end passes through the through hole of the rubber plug, and the other end is fixed by a high-strength fastener bolt.

[0017] In the above-mentioned intelligent measurement system for cast-in-place pile deformation and steel cage length, further, the intelligent measurement system for cast-in-place pile deformation and steel cage length also includes a wireless data transceiver and a data receiving and processing system, and the wireless data transceiver receives the measurement data of the distributed fiber grating and / or enameled metal wire, and transmits it to the data receiving and processing system via wireless.

[0018] A method for intelligently testing deformation of a cast-in-place pile and the length of a steel cage, wherein the method adopts the intelligent measuring system for deformation of a cast-in-place pile and the length of a steel cage as described above.

[0019] In the above-mentioned intelligent testing method for cast-in-place pile deformation and steel cage length, further, the intelligent testing method for cast-in-place pile deformation and steel cage length comprises the following steps:

[0020] Step 1: Connect multiple smart cladding steel bars through sleeves, and the length of the connected steel bars is the same as the designed length of the steel cage;

[0021] Step 2: Insert the distributed fiber Bragg grating cable and the enameled metal wire into the fiber Bragg grating reserved hole and the enameled metal wire reserved hole respectively, pass through the bottom of the smart coated steel bar, and then fix it with high-strength fastener bolts; insert the rubber plug into the fiber Bragg grating reserved hole and the enameled metal wire reserved hole after passing through the distributed fiber Bragg grating cable and the enameled metal wire respectively;

[0022] Step 3: Steel cage processing: Use smart covering steel bars to replace at least one conventional steel bar on the bored pile, and use conventional steel bars for reinforcement at other locations;

[0023] Step 4: On-site pile foundation construction: first, high-pressure jet grouting piles are constructed, followed by bored cast-in-place pile construction;

[0024] Step 5: Connect the distributed fiber grating cables and enameled metal wires on the upper part of the intelligent coated steel bar to the wireless data transceiver, and use the data receiving and processing system to receive and process the monitoring data.

[0025] One or more technical solutions provided in the embodiments of the present application have at least the following beneficial effects:

[0026] 1. The present invention is mainly used for intelligent monitoring and detection of deformation of foundation pits supported by bored piles and construction quality of bored piles. Based on the deficiencies of the prior art, distributed fiber gratings and resistance depth sounding lines are implanted in the reserved holes of the coating steel bars to form intelligent coating steel bars. After replacing the steel bars at specific positions of the bored pile steel cage and connecting the measuring fiber grating demodulator and depth sounder, a measurement system for online monitoring of the steel cage length and horizontal displacement of the foundation pit is realized, which is of great significance to ensuring the construction quality of bored piles and the safety of foundation pit construction.

[0027] 2. The present invention uses CFRP bars with fiber Bragg grating reserved holes and enameled metal wire reserved holes on both sides to solve the problem that the stiffness of the inclinometer tube in the prior art is different from that of the concrete of the cast-in-place pile, resulting in inconsistent deformation of the two.

[0028] 3. The present invention connects two intelligent covering steel bars through a sleeve, thus solving the problem of the prior art in which the joint position is dislocated due to the horizontal displacement of the soil.

[0029] 4. The present invention uses a sleeve, which does not require welding and will not damage the optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The technical solutions of the embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings, but it should be noted that these drawings are designed only for explanation purposes and are not intended to limit the scope of the present application. In addition, unless otherwise specified, these drawings are intended only to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0031] Figure 1 It is a schematic diagram of a system for measuring deformation of a cast-in-place pile body and length of a steel cage based on intelligent coated steel bars of the present invention;

[0032] Figure 2 It is a schematic diagram of the structure of the intelligent covering steel bar in the present invention;

[0033] Figure 3 This is a connection diagram of the intelligent covering steel bars in the present invention;

[0034] Figure 4 It is a schematic diagram of the application of the present invention in foundation pit support.

[0035] In the figure: 1 is a bored pile, 2 is a high-pressure jet grouting pile, 3 is a wireless data transceiver, and 4 is a data receiving and processing system;

[0036] 5 is an intelligent coated steel bar, 6 is a conventional steel bar, 7 is a stainless steel coating, 8 is a CFRP bar, 9 is a fiber Bragg grating reserved hole, 10 is an enameled metal wire reserved hole, 11 is a distributed fiber Bragg grating cable, 12 is an enameled metal wire, 13 is a sleeve, 14 is a high-strength fastener bolt, 15 is a rubber plug, and 16 is an anchor rod. DETAILED DESCRIPTION

[0037] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0038] Example 1

[0039] The intelligent coated steel bar 5 is composed of a stainless steel coating 7, a CFRP bar 8, a fiber Bragg grating reserved hole 9, and an enameled metal wire reserved hole 10. The CFRP bar 8 is a smooth round bar with holes reserved on both sides, which are the fiber Bragg grating reserved hole 9 and the enameled metal wire reserved hole 10, which are used to measure the horizontal displacement of the pile foundation and the length of the steel cage when the bored pile is used as a supporting pile.

[0040] The two intelligent covering steel bars 5 are connected by a sleeve 13. Figure 3 The sleeve and the covering steel bar are both provided with marks, the sleeve has threads inside, the covering steel bar has threads outside, the covering steel bar on the upper part of the sleeve and the covering steel bar on the lower part of the sleeve are aligned with the marks on the sleeve before starting to tighten, and it is ensured that after several turns of tightening, the reserved holes of the upper and lower covering steel bars are aligned. In short, the sleeve 13 can ensure that after the covering steel bar 5 is screwed in, the reserved holes between the upper and lower bars are aligned.

[0041] A high-strength fastener bolt 14 is designed at the bottom of the intelligent coated steel bar 5. The high-strength fastener bolt 14 includes a screw and a nut. The middle of the screw is a hollow inner hole. A side hole is opened on the side of the screw below the nut. The side hole is connected to the inner hole. After the distributed fiber grating 11 and the enameled metal wire 12 pass through the inner hole and the side hole of the high-strength fastener bolt 14, they are tightened to the bottom of the coated steel bar 5 by the nut. A rubber plug 15 with a hole in the center is designed on the top. When the distributed fiber grating 11 and the enameled metal wire 12 pass through the fiber grating reserved hole 9 and the enameled metal wire reserved hole 10, they are inserted into the holes to ensure that the distributed fiber grating 11 and the enameled metal wire 12 are in a tensioned state.

[0042] Example 2

[0043] The invention discloses an intelligent measuring system for deformation of a cast-in-place pile and length of a steel cage, which is composed of an intelligent coating steel bar 5, a wireless data transceiver 3 and a data receiving and processing system 4.

[0044] The wireless data transceiver 3 is used to receive the measurement data of the distributed optical fiber grating 11 and the enameled metal wire 12, and transmit the measurement data to the data receiving and processing system 4 via wireless.

[0045] The data receiving and processing system 4 is used to receive the pile horizontal displacement data measured by the distributed fiber grating 11 and the steel cage length data measured by the enameled metal wire 12 transmitted by the wireless data transceiver 3, and perform real-time analysis and processing.

[0046] Example 3

[0047] The test method of the intelligent measurement system for cast-in-place pile deformation and steel cage length specifically includes the following steps:

[0048] Step 1: Connect multiple smart coating steel bars 5 through sleeves 13, and the length of the connected steel bars is the same as the designed length of the steel cage.

[0049] Step 2: Insert the distributed fiber grating cable 11 and the enameled metal wire 12 into the fiber grating reserved hole 9 and the enameled metal wire reserved hole 10 respectively, pass through the bottom of the intelligent coated steel bar 5, and fix it with high-strength fastener bolts 14 to fix the bottom cable; pass the rubber plug 15 through the distributed fiber grating cable 11 and the enameled metal wire 12 respectively, and then insert it into the fiber grating reserved hole 9 and the enameled metal wire reserved hole 10 to fix the top cable.

[0050] Step 3: Welding and processing of the steel cage, using a single intelligent coating steel bar 5 to replace the outermost steel bars on the foundation pit of the bored pile 1, and using conventional steel bars 6 for reinforcement at other locations.

[0051] Step 4: On-site pile foundation construction, first drive high-pressure jet grouting piles 2 to form a cement-soil composite in the soil and consolidate the soil layer. Then carry out bored cast-in-place pile construction 1, drilling holes, lowering steel cages, and pouring concrete. After the construction is completed, the two are engaged to achieve water stopping of the foundation pit.

[0052] Step 5: Connect the distributed fiber grating cable 11 and the enameled metal wire 12 on the upper part of the intelligent coated steel bar 5 to the wireless data transceiver 3, and use the data receiving and processing system 4 to receive and process the monitoring data to guide the construction in real time.

[0053] Step 6: After the bored piles 1 and the high-pressure jet grouting piles 2 are constructed, the foundation pit is excavated. The bored piles 1 can be used as cantilever piles or can be used in conjunction with the anchor rods 16 for joint support.

[0054] Step 7: After the overall construction is completed, the wireless data transceiver device 3 is recovered.

[0055] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0056] This embodiment adopts the pre-embedded method to pre-fix the distributed fiber grating cable and the resistance depth measurement line inside the intelligent coated steel bar, and uses the intelligent coated steel bar to replace the traditional steel bar to monitor the length of the steel cage and the horizontal displacement of the foundation pit. The test accuracy is high and real-time online monitoring is realized, which is of great significance to ensure the construction quality of bored piles and the safety of foundation pit construction. In addition, the system does not require the drilling equipment to enter and exit the site multiple times, and does not require destructive drilling of bored piles. The economic benefits are obvious and have certain promotion value.

[0057] In summary, the present invention provides an intelligent measurement system and test method for bored pile deformation and steel cage length based on intelligent coated steel bar technology, which can measure the horizontal displacement of bored pile body and steel cage length, and can realize online monitoring of bored pile construction quality and foundation pit construction safety.

[0058] The above embodiments describe the present invention in detail, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. An intelligent cladding steel bar, characterized in that: The smart cladding steel bar comprises a CFRP bar, an end surface of the CFRP bar is provided with a through hole, a central axis of the through hole is parallel to the central axis of the CFRP bar, and the outer side of the CFRP bar is covered by a stainless steel cladding; The number of the through holes is two, which are recorded as a fiber grating reserved hole and an enameled metal wire reserved hole; A high-strength fastener bolt is provided at one end of the through hole, and the high-strength fastener bolt includes a screw and a nut, the middle of the screw is a hollow inner hole, and a side hole is opened on the side of the screw below the nut, and the side hole is connected to the inner hole; a rubber plug is inserted into the through hole, and a hole is provided in the center of the rubber plug; Both the sleeve and the covering steel bar are marked, the sleeve has threads inside, and the covering steel bar has threads outside. The covering steel bars on the upper part of the sleeve and the covering steel bars on the lower part of the sleeve are aligned with the marks on the sleeve before starting to tighten. Ensure that after several turns of tightening, the reserved holes of the upper and lower covering steel bars are aligned. The sleeve is used to ensure that after the covering steel bars are screwed in, the reserved holes between the upper and lower bars are aligned.

2. An intelligent measurement system for cast-in-place pile deformation and steel cage length, characterized by: The intelligent measurement system for cast-in-place pile deformation and steel cage length comprises the intelligent coated steel bar according to claim 1, and the intelligent coated steel bar replaces at least one conventional steel bar on the steel cage.

3. The intelligent measurement system for cast-in-place pile deformation and steel cage length according to claim 2 is characterized by: The two intelligent covering steel bars are connected via a sleeve.

4. The intelligent measurement system for cast-in-place pile deformation and steel cage length according to claim 2 is characterized by: The distributed optical fiber grating and / or the enameled metal wire passes through the through hole, one end passes through the through hole of the rubber plug, and the other end is fixed by a high-strength fastener bolt.

5. The intelligent measurement system for cast-in-place pile deformation and steel cage length according to claim 4 is characterized in that: The intelligent measurement system for cast-in-place pile deformation and steel cage length also includes a wireless data transceiver and a data receiving and processing system. The wireless data transceiver receives the measurement data of the distributed fiber grating and / or enameled metal wire and transmits it to the data receiving and processing system via wireless.

6. An intelligent testing method for cast-in-place pile deformation and steel cage length, characterized by: The intelligent testing method for cast-in-place pile deformation and steel cage length adopts the intelligent measurement system for cast-in-place pile deformation and steel cage length as described in any one of claims 2-5.

7. The intelligent testing method for cast-in-place pile deformation and steel cage length according to claim 6 is characterized by: The intelligent testing method for cast-in-place pile deformation and steel cage length comprises the following steps: Step 1: Connect multiple smart cladding steel bars through sleeves, and the length of the connected steel bars is the same as the designed length of the steel cage; Step 2: Insert the distributed fiber Bragg grating cable and the enameled metal wire into the fiber Bragg grating reserved hole and the enameled metal wire reserved hole respectively, pass through the bottom of the smart coated steel bar, and then fix it with high-strength fastener bolts; insert the rubber plug into the fiber Bragg grating reserved hole and the enameled metal wire reserved hole after passing through the distributed fiber Bragg grating cable and the enameled metal wire respectively; Step 3: Steel cage processing: Use smart covering steel bars to replace at least one conventional steel bar on the bored pile, and use conventional steel bars for reinforcement at other locations; Step 4: On-site pile foundation construction: first, high-pressure jet grouting piles are constructed, followed by bored cast-in-place pile construction; Step 5: Connect the distributed fiber grating cables and enameled metal wires on the upper part of the intelligent coated steel bar to the wireless data transceiver, and use the data receiving and processing system to receive and process the monitoring data.

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