Fiber-optic-based piston-type large-deformation prestressed anchor cable monitoring device and construction method

Abstract

The present invention provides an optical fiber-based piston-type large-deformation prestressed anchor cable monitoring device and a construction method, comprising a piston-type large-deformation prestressed anchor cable, an anchor cable axial force monitoring device, a piston slippage monitoring device and an edge / landslide deformation position monitoring device. The piston-type large-deformation prestressed anchor cable is a piston-type large-deformation device arranged at the end of the anchoring section, and the piston-type large-deformation device comprises a pressure plate, a large-tonnage spring and a piston cylinder; the anchor cable axial force monitoring is an axial force monitoring sensor arranged between the pressure plate and the large-tonnage spring; the piston slippage monitoring device is a displacement monitoring sensor arranged between the guide head and the pressure plate. The monitoring device of the present application has a device that simultaneously and automatically monitors the three monitoring indicators of the sliding force, deformation and deformation position of the edge / landslide, and can be widely used in the fields of mineral resources, hydropower resources and transportation infrastructure.

Description

Technical Field

[0001] The present invention relates to the field of automated monitoring technology, and in particular to an optical fiber-based piston-type large-deformation prestressed anchor cable monitoring device and a monitoring method. Background Art

[0002] Currently, the main monitoring methods for edge / landslide deformation include deep displacement monitoring, surface displacement monitoring and landslide force monitoring.

[0003] The inventors of this application discovered that while conventional constant-resistance, high-deformation anchor cables can simultaneously and automatically monitor their axial force and slippage, they cannot accurately determine the location of edge / slope deformation. Currently, there are no reports of automated, real-time monitoring devices for the axial force, slippage, and edge / slope deformation of prestressed anchor cables with high deformation. Summary of the Invention

[0004] The embodiments of the present application provide an optical fiber-based piston-type large deformation prestressed anchor cable monitoring device and construction method, aiming to solve the problem that traditional constant resistance large deformation anchor cables cannot simultaneously monitor the deformation parts of the edge / landslide.

[0005] In order to solve the above technical problems, the technical solution proposed in this application is:

[0006] The present invention provides an optical fiber-based piston-type large-deformation prestressed anchor cable monitoring device, comprising: a piston-type large-deformation prestressed anchor cable, an anchor cable axial force monitoring device, a piston slippage monitoring device, and a slope deformation location monitoring device;

[0007] The piston-type large deformation prestressed anchor cable includes a guide head, a piston-type large deformation device, a steel strand, and an anchor; the piston-type large deformation device includes a pressure plate, a spring, and a piston cylinder. The two ends of the spring are respectively abutted against the pressure plate and the bottom plate of the piston cylinder and can move in the piston cylinder. The guide head is fixed to the front end of the piston cylinder. One end of the steel strand is anchored to the pressure plate, and the other end is anchored to the anchor.

[0008] The anchor cable axial force monitoring device includes a limit plate, a bolt and a piezoresistive pressure sensor. A fixing hole with a thread corresponding to the bolt is opened on the pressure plate. The piezoresistive pressure sensor is placed between the limit plate and the pressure plate and fixed with bolts.

[0009] The piston slippage monitoring device includes a hook screw, a displacement sensor and a hook on a guide head. The hook is preset inside the guide head, a hole is opened on the front side of the pressure plate to provide a thread corresponding to the hook screw, the hook screw is fixed to the pressure plate, and the displacement sensor is fixed between the hook screw and the hook;

[0010] The slope deformation monitoring device includes a distributed optical fiber and a rope buckle for fixing the optical fiber. The distributed optical fiber is tied to the steel strand through the rope buckle and fixed along its entire length by cement slurry.

[0011] Furthermore, the pressure value F1 of the piezoresistive pressure sensor is calculated as follows:

[0012] ;

[0013] Where: U represents the voltage across the piezoresistive pressure sensor; represents the ratio of the unit pressure of the piezoresistive pressure sensor to its elongation; S represents the cross-sectional area of ​​the piezoresistive pressure sensor; I represents the current at both ends of the piezoresistive pressure sensor; k represents the ratio of the unit resistance of the piezoresistive pressure sensor to its elongation.

[0014] Furthermore, the spring compression deformation calculation formula is:

[0015] ;

[0016] Where: F2 represents the preload of the steel strand, G represents the shear modulus of elasticity of the spring, d represents the diameter of the spring steel, D represents the center diameter of the spring, and n represents the effective number of coils of the spring. Represents the compression deformation of the spring; considering the tensile deformation and elongation of the slope deformation steel strand, the compression deformation value of the spring is less than or equal to the deformation value of the slope.

[0017] The calculation formula for the change range of the pressure plate movement is:

[0018]

[0019] Where: l represents the length of the displacement sensor when no prestressing is applied; x represents the length of the displacement sensor after prestressing is applied.

[0020] Furthermore, when the slope deforms, the distributed optical fiber can accurately monitor the deformation position of the cement slurry. Combined with the drilling angle, the depth h of the sliding surface can be determined, that is:

[0021]

[0022] Where: h represents the depth of the sliding surface, Represents the distance between the deformation site monitored by distributed optical fiber and the orifice; Represents the angle between the length direction of the drill hole and the horizontal direction.

[0023] Furthermore, the distributed optical fiber includes a pulse optical signal generator, several circulators and optical detectors. The pulse optical signal generator is installed at one end of the distributed optical fiber. The emitted optical signal generates Brillouin scattering and then passes through the circulator and is received by the optical detector arranged at the other end of the distributed optical fiber.

[0024] Furthermore, it also includes: a data acquisition and processing system, which is used to collect and process monitoring signals from the anchor cable axial force monitoring device, the piston slippage monitoring device and the slope deformation part monitoring device.

[0025] On the other hand, the present application also protects a construction method of the aforementioned optical fiber-based piston-type large deformation prestressed anchor cable monitoring device, comprising the following steps:

[0026] S1: Install a spring into the piston cylinder and seal the pressure plate at the entrance of the piston cylinder so that both ends of the spring abut against the bottom plate of the piston cylinder and the pressure plate respectively;

[0027] S2: A fixing hole with a thread corresponding to the bolt is opened on the pressure plate, and a piezoresistive pressure sensor is placed between the limit plate and the pressure plate and fixed with bolts;

[0028] S3: Pass the steel strand through the preset holes on the piston cylinder and the pressure plate, and anchor one end of the steel strand to the pressure plate through the extrusion sleeve, and fix the other end of the steel strand through a temporary anchoring device;

[0029] S4: Four hooks are preset inside the guide head. Holes are opened on the front face of the pressure plate to provide threads corresponding to the hook screws. The hook screws are fixed to the threads. The displacement sensor is fixed between the hook screws and the guide head hooks. The guide head is then fastened to the piston cylinder.

[0030] S5: Arrange the distributed optical fiber along the entire length of the steel strand and secure it with a rope lock;

[0031] S6: Drill a hole at a preset point, install the overall structure formed in step S5 in the hole, inject cement slurry into the hole to form a grouting body, construct a frame beam, place a steel plate on the frame beam, place an anchor on the steel plate, tension the steel strand, apply prestress, and then seal the anchor to form an anchor pier.

[0032] Furthermore, the method further includes: in steps S2 and S4: respectively leading out the piezoresistive sensor and the displacement sensor along the steel strand through wires.

[0033] Furthermore, the method further includes: S7: connecting the wires of the piezoresistive pressure sensor and the displacement sensor to the data acquisition instrument, connecting the distributed optical fiber to the modem, and connecting them to the data acquisition and processing system respectively.

[0034] Compared with the existing technology, the optical fiber-based piston-type large deformation prestressed anchor cable monitoring device and construction method of the present invention have achieved the following beneficial technical effects:

[0035] The optical fiber-based piston-type large-deformation prestressed anchor cable monitoring device and construction method of the present invention can be flexibly set according to protection needs, and can simultaneously obtain three monitoring indicators of the edge / landslide, namely the landslide force, deformation amount and deformation position, through a single drilling hole, greatly reducing the monitoring cost of the edge / landslide. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is a structural diagram of an optical fiber-based piston-type large deformation prestressed anchor cable monitoring device provided in an embodiment of the present invention.

[0038] Figure 2 A longitudinal cross-sectional view of the large deformation structure of a piston of an optical fiber-based large deformation prestressed anchor cable monitoring device provided in an embodiment of the present invention.

[0039] Figure 3 A cross-sectional view of the large deformation structure of a piston of an optical fiber-based large deformation prestressed anchor cable monitoring device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0041] like Figure 1 and Figure 2 As shown, the present application provides an optical fiber-based piston-type large deformation prestressed anchor cable monitoring device, comprising: a piston-type large deformation prestressed anchor cable, an anchor cable axial force monitoring device, a piston slippage monitoring device, and an edge / landslide deformation portion monitoring device;

[0042] like Figure 3As shown, the piston-type large deformation prestressed anchor cable includes a guide head 3, a piston-type large deformation device 5, a steel strand 6, and an anchor 9; the piston-type large deformation device 5 includes a pressure plate 501, a spring 502, and a piston cylinder 503. The two ends of the spring 502 are respectively abutted on the pressure plate 501 and the bottom plate of the piston cylinder 503 and can move in the piston cylinder 503. The guide head 3 is fixed to the front end of the piston cylinder 503. One end of the steel strand 6 is anchored on the pressure plate 501, and the other end is anchored on the anchor 9.

[0043] The anchor cable axial force monitoring device includes a limit plate 12, a bolt 13 and a piezoresistive pressure sensor 14. A fixing hole with a thread corresponding to the bolt 13 is opened on the pressure plate 501. The piezoresistive pressure sensor 14 is placed between the limit plate 12 and the pressure plate 501 and fixed with the bolt 13.

[0044] The piston slippage monitoring device includes a hook screw 15, a displacement sensor 16 and a hook 17 on the guide head. The hook 17 is preset inside the guide head 3, and a hole is opened on the front side of the pressure plate 501 to set a thread corresponding to the hook screw 15. The hook screw 15 is fixed on the pressure plate 501, and the displacement sensor 16 is fixed between the hook screw 15 and the hook 17; the displacement sensor 16 can monitor the slip deformation value of the landslide in real time.

[0045] The device for monitoring the deformation of landslides includes a distributed optical fiber 11 and a rope clip 18 for securing the optical fiber. The distributed optical fiber 11 is tied to the steel strand 6 via the rope clip 18 and secured along its entire length with cement slurry 2. The distributed optical fiber 11 is installed along the entire length of the steel strand 6, from the bottom of the anchoring section (extrusion sleeve 4) to the opening (anchor 9) of the free section.

[0046] The pressure value F1 of the piezoresistive pressure sensor 14 is calculated using the following formula:

[0047] ;

[0048] Wherein: U represents the voltage across the piezoresistive pressure sensor 14; represents the ratio of the unit pressure of the piezoresistive pressure sensor 14 to its elongation deformation; S represents the cross-sectional area of ​​the piezoresistive pressure sensor 14; I represents the current at both ends of the piezoresistive pressure sensor 14; k represents the ratio of the unit resistance of the piezoresistive pressure sensor 14 to its elongation deformation.

[0049] The calculation formula of the compression deformation of the spring 502 is:

[0050] ;

[0051] Where: F2 represents the preload of the steel strand 6, G represents the shear modulus of elasticity of the spring 502, d represents the diameter of the steel material of the spring 502, D represents the center diameter of the spring 502, and n represents the effective number of turns of the spring 502. represents the compression deformation of the spring 502;

[0052] The calculation formula for the variation range of the movement of the pressure plate 501 is:

[0053]

[0054] Wherein: l represents the length of the displacement sensor 16 when no prestress is applied; x represents the length of the displacement sensor 16 after prestress is applied.

[0055] In the embodiment of the present application, four fixing holes with corresponding threaded holes for bolts are opened on the pressure plate 501. A piezoresistive pressure sensor 14 is placed between the limit plate 12 and the pressure plate 501 and secured with bolts. The spring 502 contacts the limit plate 12. This prevents the anchor cable from breaking during earthquakes or landslide deformation.

[0056] In the embodiment of the application, the distributed optical fiber 11 is fixed to the steel strand 6 via a rope clip 18. After the stress anchor cable of the large deformation piston device is installed in the borehole 1, cement slurry 2 is injected into the borehole 1. The entire length of the distributed optical fiber is bonded to the cement slurry 2. When the landslide deforms, the distributed optical fiber can accurately monitor the deformation position of the cement grouting body. Combined with the drilling angle, the depth of the sliding surface can be determined, that is:

[0057]

[0058] Where: h represents the depth of the sliding surface, Represents the distance between the deformation site monitored by distributed optical fiber and the orifice; Represents the angle between the length direction of the drill hole and the horizontal direction.

[0059] The present application discloses a construction method for an optical fiber-based piston-type large-deformation prestressed anchor cable monitoring device, comprising the following steps:

[0060] S1: Install the spring 502 into the piston cylinder 503 and seal the pressure plate 501 at the entrance of the piston cylinder 503 so that both ends of the spring 502 abut against the bottom plate of the piston cylinder 503 and the pressure plate 501 respectively;

[0061] S2: Open a fixing hole with a thread corresponding to the bolt 13 on the pressure plate 501, place the piezoresistive pressure sensor 14 between the limit plate 12 and the pressure plate 501, and fix it with the bolt 13;

[0062] S3: Pass the steel strand 6 through the preset holes on the piston cylinder 503 and the pressure plate 501, and anchor one end of the steel strand 6 on the pressure plate 501 through the extrusion sleeve 4, and fix the other end of the steel strand 6 through a temporary anchoring device;

[0063] S4: Four hooks 17 are pre-set inside the guide head 3. Threads corresponding to the hook screws 15 are opened on the front surface of the pressure plate 501. The hook screws 15 are fixed to the threads. The displacement sensor 16 is fixed between the hook screws 15 and the guide head hooks 17. The guide head 3 is then fastened to the piston cylinder 503.

[0064] S5: Arrange the distributed optical fiber 11 along the entire length of the steel strand 6 and secure it with a rope lock 18;

[0065] S6: Drill a borehole 1 at a preset point, install the overall structure formed in step S5 in the borehole 1, inject cement slurry 2 into the borehole 1 to form a grouting body, construct a frame beam 7, place a steel pad 8 on the frame beam, place an anchor 9 on the steel pad 8, tension the steel strand 6, apply prestress, and then seal the anchor to form an anchor pier 10.

[0066] The method further includes: in steps S2 and S4: respectively leading the piezoresistive sensor 14 and the displacement sensor 16 along the steel strand 6 through wires.

[0067] It also includes: S7: connecting the wires of the piezoresistive pressure sensor 14 and the displacement sensor 16 to the acquisition instrument for communication, connecting the distributed optical fiber 11 to the modem for communication, and connecting them to the data acquisition and processing system respectively.

[0068] The invention patent achieves large deformation of the edge / landslide, and can also capture the three monitoring indicators of the sliding force, sliding amount and deformation position of the edge / landslide in real time, and obtain automatic real-time monitoring and data display at the same time.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A construction method of an optical fiber-based piston-type large deformation prestressed anchor cable monitoring device, characterized in that: The monitoring device includes: a piston-type large deformation prestressed anchor cable, an anchor cable axial force monitoring device, a piston slippage monitoring device and an edge / landslide deformation part monitoring device; The piston-type large deformation prestressed anchor cable comprises a guide head (3), a piston-type large deformation device (5), a steel strand (6), and an anchor (9); the piston-type large deformation device (5) comprises a pressure plate (501), a spring (502), and a piston cylinder (503); the two ends of the spring (502) are respectively abutted against the bottom plates of the pressure plate (501) and the piston cylinder (503), and can move in the piston cylinder (503); the guide head (3) is fixed to the front end of the piston cylinder (503); one end of the steel strand (6) is anchored to the pressure plate (501), and the other end is anchored to the anchor (9); The anchor cable axial force monitoring device comprises a limit plate (12), a bolt (13) and a piezoresistive pressure sensor (14); a fixing hole with a thread corresponding to the bolt (13) is provided on the pressure plate (501); the piezoresistive pressure sensor (14) is placed between the limit plate (12) and the pressure plate (501) and fixed with the bolt (13); The piston slippage monitoring device comprises a hook screw (15), a displacement sensor (16) and a hook (17) on a guide head. The hook (17) is preset inside the guide head (3). A thread corresponding to the hook screw (15) is provided in a hole on the front side of the pressure plate (501). The hook screw (15) is fixed on the pressure plate (501). The displacement sensor (16) is fixed between the hook screw (15) and the hook (17). The edge / landslide deformation monitoring device comprises a distributed optical fiber (11) and a rope buckle (18) for fixing the optical fiber, wherein the distributed optical fiber (11) is tied to the steel strand (6) through the rope buckle (18) and fixed along its entire length by cement slurry (2); The pressure value F1 calculation formula of the piezoresistive pressure sensor (14) is: Where: U represents the voltage across the piezoresistive pressure sensor (14); K ε represents the ratio of the unit pressure of the piezoresistive pressure sensor (14) to its elongation deformation; S represents the cross-sectional area of ​​the piezoresistive pressure sensor (14); I represents the current at both ends of the piezoresistive pressure sensor (14); k represents the ratio of the unit resistance of the piezoresistive pressure sensor (14) to its elongation deformation; The construction method comprises the following steps: S1: Install a spring (502) into the piston cylinder (503), and seal the pressure plate (501) at the entrance of the piston cylinder (503) so that both ends of the spring (502) are in contact with the bottom plate of the piston cylinder (503) and the pressure plate (501) respectively; S2: A fixing hole with a thread corresponding to the bolt (13) is opened on the pressure plate (501), a piezoresistive pressure sensor (14) is placed between the limit plate (12) and the pressure plate (501), and fixed with the bolt (13); S3: The steel strand (6) is passed through the preset holes on the piston cylinder (503) and the pressure plate (501), and one end of the steel strand (6) is anchored on the pressure plate (501) through the extrusion sleeve (4), and the other end of the steel strand (6) is fixed by a temporary anchoring device; S4: Four hooks (17) are preset inside the guide head (3), and threads corresponding to the hook screws (15) are opened on the front end surface of the pressure plate (501). The hook screws (15) are fixed on the threads, and the displacement sensor (16) is fixed between the hook screws (15) and the guide head hooks (17). Then, the guide head (3) is fastened to the piston cylinder (503); S5: Arrange the distributed optical fiber (11) along the entire length of the steel strand (6) and secure it with a rope lock (18); S6: Drill a borehole (1) at a preset point, install the integral structure formed in step S5 in the borehole (1), inject cement slurry (2) into the borehole (1) to form a grouting body, construct a frame beam (7), place a steel pad (8) on the frame beam, place an anchor (9) on the steel pad (8), tension the steel strand (6), apply prestress, and then seal the anchor to form an anchor pier (10).

2. The construction method of the optical fiber-based piston-type large deformation prestressed anchor cable monitoring device according to claim 1 is characterized in that: The calculation formula of the compression deformation of the spring (502) is: Where: F2 represents the preload of the steel strand (6), G represents the shear elastic modulus of the spring (502), d represents the diameter of the steel material of the spring (502), D represents the center diameter of the spring (502), n represents the effective number of turns of the spring (502), and Δl represents the compression deformation of the spring (502); considering that the steel strand deformed by the edge / landslide is stretched and elongated, the compression deformation value of the spring is less than or equal to the deformation value of the edge / landslide; The calculation formula of the variation range of the movement of the pressure plate (501) is: l≤x≤l+Δl Wherein: l represents the length of the displacement sensor (16) when no prestress is applied; x represents the length of the displacement sensor (16) after the prestress is applied.

3. The construction method of the optical fiber-based piston-type large deformation prestressed anchor cable monitoring device according to claim 1 is characterized in that: When the edge / slide deforms, the distributed optical fiber (11) can accurately monitor the deformation position of the cement slurry (2). Combined with the drilling angle, the depth h of the sliding surface can be determined, that is: h=x l ×sinα Where: h represents the depth of the sliding surface, x l represents the distance between the deformation part monitored by distributed optical fiber and the hole mouth; α represents the angle between the length direction of the borehole and the horizontal direction.

4. The construction method of the optical fiber-based piston-type large deformation prestressed anchor cable monitoring device according to claim 3 is characterized in that: The distributed optical fiber (11) includes a pulse optical signal generator, a plurality of circulators and a light detector. The pulse optical signal generator is installed at one end of the distributed optical fiber (11). The emitted optical signal generates Brillouin scattering, passes through the circulator, and is received by the light detector arranged at the other end of the distributed optical fiber (11).

5. The construction method of the optical fiber-based piston-type large deformation prestressed anchor cable monitoring device according to claim 1 is characterized in that: Also includes: The data acquisition and processing system is used to collect and process monitoring signals from the anchor cable axial force monitoring device, the piston slippage monitoring device and the edge / landslide deformation part monitoring device.

6. The construction method of the optical fiber-based piston-type large deformation prestressed anchor cable monitoring device according to claim 1 is characterized in that: Also includes: In steps S2 and S4: the piezoresistive pressure sensor (14) and the displacement sensor (16) are respectively led out along the steel strand (6) through wires.

7. The construction method of the optical fiber-based piston-type large deformation prestressed anchor cable monitoring device according to claim 1 is characterized in that: Also includes: S7: Connect the wires of the piezoresistive pressure sensor (14) and the displacement sensor (16) to the acquisition instrument, connect the distributed optical fiber (11) to the modem, and connect them to the data acquisition and processing system respectively.

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