A device and method for detecting the anchoring quality of prestressed anchor cables on slopes

Abstract

The present invention belongs to the technical field of slope cable detection, and particularly relates to a device and a method for detecting the anchoring quality of prestressed cables on slopes. Stress wave excitation devices are connected to both ends of the steel strand. The percussion hammer of the stress wave excitation device is slidably arranged inside a hollow sleeve provided with a magnetization circuit. Permanent magnets are arranged on the left end cover assembly and / or the right end cover, and an elastic excitation member is arranged on the right end cover. By using the cooperation of the magnetization circuit, the percussion hammer, the permanent magnets, and the elastic excitation member, stress wave pulse signals are generated at the ends of the cable. By connecting stress wave excitation devices to both ends of the steel strand and remotely controlling the magnetization circuit by the controller to magnetize or demagnetize the percussion hammer, stress wave pulse signals are synchronously generated at both ends of the cable. The two stress wave pulse signals are superimposed and enhanced during propagation, reducing the signal attenuation amplitude of the stress wave pulse signals during long-distance propagation and ensuring that the stress wave pulse signals can be effectively collected.

Description

Technical Field

[0001] The present invention belongs to the technical field of slope anchor cable detection, and particularly relates to a device and a method for detecting the anchoring quality of prestressed anchor cables for slopes. Background Art

[0002] The prestressed anchor cable can anchor the shallow unstable sliding mass of the slope and the deep stable rock mass together by applying prestress to itself, so as to reliably improve the overall stability of the slope and is widely used in slope reinforcement projects. In order to ensure that the prestressed anchor cable can reach the predetermined anchoring force, on the one hand, the prestressed anchor cable should meet the designed length so that it can penetrate through the unstable rock and soil layers to the stable rock and soil layers, and on the other hand, the grouting quality of the anchoring section of the prestressed anchor cable should be ensured, that is, there are no defects in the anchoring section so that it can provide sufficient tensile capacity. However, the prestressed anchor cable for slopes belongs to an underground hidden project. After its construction is completed, it is impossible to use intuitive means to judge whether the prestressed anchor cable can meet the above two requirements. Therefore, it is necessary to detect the anchoring quality of the prestressed anchor cable for slopes, so as to identify the construction deficiencies of the prestressed anchor cable for slopes at an early stage and realize the effective supervision of the construction quality of the prestressed anchor cable.

[0003] The traditional method for detecting the anchoring quality of prestressed anchor cables for slopes is usually the pull-out method, which conducts partial sampling inspection on the prestressed anchor cables for slopes by pulling out the prestressed anchor cables. Although this method is the most intuitive, it is destructive, troublesome to operate and has a high detection cost. More importantly, it is impossible to detect all the prestressed anchor cables for slopes, making it difficult to be widely applied in actual projects. Therefore, there is an urgent need in the engineering field for a non-destructive detection technology for the anchoring quality of prestressed anchor cables for slopes.

[0004] At present, the non-destructive detection technology for the anchoring quality of prestressed anchor cables for slopes is mainly realized by the method of embedding components and the stress wave reflection method. The method of embedding components is to paste components such as strain gauges and anchor cable meters on the surface of the anchor cable to monitor the anchoring quality of the prestressed anchor cable for a long time. However, the components are extremely easy to be damaged during use, making the effect of this detection often poor. In addition, the components can only detect the local health status of the prestressed anchor cable and are difficult to reflect the overall quality of the anchor cable, which is not conducive to engineering personnel making accurate judgments. The principle of the stress wave reflection method is to generate a stress wave pulse signal at one end of the anchor cable. For example, the existing patent with the publication number CN206378464U discloses a scheme. The stress wave pulse signal propagates back and forth inside the prestressed anchor cable and generates reflections at different interfaces, and then these stress wave signal pulse signals are received by the sensor arranged at the end, and then the time domain, frequency spectrum and energy attenuation of the signals are analyzed to realize the rapid evaluation of the global quality of the anchor cable. The stress wave reflection method has the advantages of economy, rapidity, simplicity and reliability, and can accurately obtain information such as the length and grouting quality of the anchor cable under the premise of non-destruction, and is widely used in the detection of the anchoring quality of prestressed anchor cables for slopes.

[0005] However, as the engineering construction advances towards difficult and dangerous areas, the engineering geological conditions of the slope become increasingly complex. When strengthening the slope, the prestressed anchor cables are designed to be longer and have a greater buried depth. Due to the energy attenuation during the propagation of stress waves, which is more obvious in the prestressed anchor cables of deep and long slopes, in the current stress wave reflection method technology, since no effective compensation or attenuation reduction is carried out, it is difficult for the stress wave sensors at the end of the anchor cable to collect effective stress wave pulse signals. Furthermore, this causes difficulties in data analysis and even leads to misjudgment of results, unable to meet the actual needs. Summary of the Invention

[0006] The present invention provides a device for detecting the anchoring quality of prestressed anchor cables for slopes, which includes an anchor cable composed of at least one positioning ring and several steel strands parallelly passing through the positioning ring. Stress wave excitation devices are connected to both ends of at least one of the steel strands; the stress wave excitation device includes a locking member, a sleeve assembly, and a hammer. The end of the steel strand is fixed inside the locking member. The sleeve assembly further includes a left end cover assembly, a hollow sleeve, and a right end cover connected in sequence. The locking member is connected to the left end cover assembly. The left end cover assembly is provided with a through hole communicating with the hollow sleeve. A stress wave sensor is arranged inside the left end cover assembly. The stress wave sensor is connected to a host computer. The stress wave sensor is provided with an avoidance through hole communicating with the through hole. A part of the end face of the steel strand is attached to the stress wave sensor for receiving stress wave pulse signals and sending the stress wave pulse signals to the host computer. Another part of the end face of the steel strand faces the avoidance through hole; the hammer is slidably arranged inside the hollow sleeve. A magnetization circuit is arranged inside the hollow sleeve. The magnetization circuit is connected to an external controller for remotely controlling the magnetization circuit to magnetize or demagnetize the hammer. Permanent magnets are arranged on the left end cover assembly and / or the right end cover. An elastic excitation member is arranged on the right end cover. When the hammer is magnetized, the hammer slides towards the right end cover under the magnetic force of the permanent magnet and compresses the elastic excitation member. When the hammer is demagnetized, the hammer moves towards the left end cover assembly under the restoring force of the elastic excitation member. A part of the hammer passes through the through hole and the avoidance through hole to impact the end face of the steel strand, thereby generating stress wave pulse signals.

[0007] In a specific embodiment, the locking member is of a cylindrical structure, which includes a rubber sleeve and two semi-cylindrical shells. The two semi-cylindrical shells are connected into a cylinder. The rubber sleeve is placed inside the two semi-cylindrical shells for covering the peripheral side wall of the end of the steel strand. The two semi-cylindrical shells are connected by bolts to lock and fix the steel strand together with the rubber sleeve.

[0008] In a specific embodiment, the left end cover assembly includes a connecting ring and a limiting plate. The first end of the connecting ring is provided with an internal thread, and the semi-circular housing is provided with an external thread. The first end of the connecting ring and the semi-circular housing are connected through the internal thread and the external thread. The limiting plate is fixed to the end of the second end of the connecting ring. The through hole is provided on the limiting plate. The stress wave sensor is connected to the limiting plate through a first spring, which is used to ensure that a part of the end face of the steel strand is in close contact with the stress wave sensor. The permanent magnet on the left end cover assembly (321) is fixed to the limiting plate.

[0009] In a specific embodiment, the hollow sleeve includes a round tube and a square tube. The square tube is placed inside the round tube, and the outer wall of the square tube and the inner wall of the round tube are connected into one body through a web plate. The hammer slides along the length direction of the square tube and is arranged inside the square tube. The hammer includes a protective shell and an iron core. The protective shell covers the outer wall of the iron core. The end of the iron core facing the limiting plate has a conical knocking part protruding from the protective shell. The magnetization circuit includes a power supply VCC, a power supply positive connection piece, a power supply negative connection piece, a coil first end connection piece, a coil second end connection piece and a coil. The power supply VCC is arranged on the square tube. The power supply positive connection piece and the power supply negative connection piece are both arranged on the inner wall of the square tube along the length direction of the square tube and are respectively connected to the positive and negative electrodes of the power supply VCC. The coil is wound around the iron core. The coil first end connection piece and the coil second end connection piece are arranged on the outer wall of the protective shell and are respectively connected to both ends of the coil. The power supply positive connection piece is in sliding contact with the coil first end connection piece, and the power supply negative connection piece is in sliding contact with the coil second end connection piece to form a conductive loop.

[0010] In a specific embodiment, a number of freely rolling balls are embedded on the outer wall of the protective shell, and the balls are in rolling contact with the inner wall of the square tube.

[0011] In a specific embodiment, the power supply positive connection piece and the power supply negative connection piece are elastic pieces.

[0012] In a specific embodiment, the magnetization circuit further includes a first optoelectronic sensor, a second optoelectronic sensor, a first silicon-controlled rectifier SCR1, an electromagnetic relay, a current-limiting resistor R1, a second silicon-controlled rectifier SCR2, and a current-limiting resistor R2. The first optoelectronic sensor is disposed on the inner wall of the square tube near the end face of the steel strand, and the second optoelectronic sensor is disposed on the inner wall of the square tube near the right end cap. The positive terminal of the photoresistor in the first optoelectronic sensor is connected to the positive electrode of the power supply VCC through a pull-up resistor R3, and the negative terminal of the photoresistor in the first optoelectronic sensor is connected to the negative electrode of the power supply VCC. The base of the triode in the first optoelectronic sensor is connected to the photoresistor in the first optoelectronic sensor through an optical path. The collector of the triode in the first optoelectronic sensor is connected to the positive electrode of the power supply VCC through a pull-up resistor R4, and the emitter of the first optoelectronic sensor is connected to the negative electrode of the power supply VCC. The anode of the first silicon-controlled rectifier SCR1 is connected to the positive electrode of the power supply VCC, the cathode of the first silicon-controlled rectifier SCR1 is connected to the positive electrode of the electromagnetic relay, the negative electrode of the electromagnetic relay is connected to the negative electrode of the power supply VCC, and the gate of the first silicon-controlled rectifier SCR1 is connected between the pull-up resistor R4 and the collector of the triode in the first optoelectronic sensor. The fixed end of the armature in the electromagnetic relay is connected to the negative electrode of the power supply VCC through a current-limiting resistor R1, and the moving end of the armature in the electromagnetic relay is in normally closed contact with the coil second-end connecting piece. The positive terminal of the photoresistor in the second optoelectronic sensor is connected to the gate of the first silicon-controlled rectifier SCR1 through a pull-up resistor R6, and the negative terminal of the photoresistor in the first optoelectronic sensor is connected to the negative electrode of the power supply VCC. The base of the triode in the first optoelectronic sensor is connected to the photoresistor in the second optoelectronic sensor through an optical path. The collector of the triode in the second optoelectronic sensor is connected to the gate of the first silicon-controlled rectifier SCR1 through a pull-up resistor R5, and the emitter of the second optoelectronic sensor is connected to the negative electrode of the power supply VCC. The anode of the second silicon-controlled rectifier SCR2 is connected to the coil second-end connecting piece, the cathode of the second silicon-controlled rectifier SCR2 is connected to the negative electrode of the power supply VCC through a current-limiting resistor R2, and the gate of the second silicon-controlled rectifier SCR2 is connected between the pull-up resistor R5 and the collector of the triode in the second optoelectronic sensor. Wherein, the resistance value of the current-limiting resistor R2 is greater than that of the current-limiting resistor R1.

[0013] In a specific embodiment, the right end cap is connected to the circular tube and the square tube. The elastic excitation member includes a second spring and a push block. The first end of the second spring is connected to the right end cap, and the second end of the second spring extends into the square tube and is connected to the push block.

[0014] The present invention also provides a method for detecting the anchoring quality of prestressed anchor cables on slopes. During construction, the first end of the anchor cable in the above detection device, together with the stress wave excitation device at the first end, is inserted into the deep rock and soil of the slope, and cement mortar is injected for dense fixation to construct the anchoring section of the anchor cable. The second end of the anchor cable is buried in the shallow rock and soil of the slope to construct the free section of the anchor cable. The end of the free section and its stress wave excitation device are fixed on the slope surface through a locking device, so that the anchor cable has prestress. During detection, the magnetization circuits of the two stress wave excitation devices are remotely controlled by an external controller to magnetize their respective percussion hammers, so that the percussion hammers compress the elastic excitation members under the magnetic force of the permanent magnets. Then, the magnetization circuits of the two stress wave excitation devices are simultaneously disconnected, causing the percussion hammers to demagnetize. The two percussion hammers simultaneously strike both ends of the anchor cable under the action of their respective elastic excitation members, and stress wave pulse signals are simultaneously excited at both ends of the anchor cable. The stress wave sensors send the stress wave pulse signals to the upper computer for analyzing the anchoring quality of the anchor cable.

[0015] In a specific embodiment, no stress wave sensor is configured in the stress wave excitation device of the anchoring section.

[0016] Advantages of the present invention: In the present invention, the stress wave excitation device realizes the generation of stress wave pulse signals at the ends of the anchor cable through the cooperation of a magnetization circuit, a percussion hammer, a permanent magnet, and an elastic excitation member, making the excitation of stress waves more convenient, autonomous, controllable, uniform, reliable, and effective. Moreover, it effectively reduces the detection cost, improves the detection efficiency, and reduces the operation difficulty, frequency, and human and material costs at the construction site. By setting stress wave excitation devices at both ends of the anchor cable and remotely controlling the magnetization circuit of the percussion hammer to magnetize or demagnetize through an external controller, stress wave pulse signals can be simultaneously generated at both ends of the anchor cable. The two stress wave pulse signals are superimposed and enhanced during propagation, reducing the signal attenuation amplitude of the stress wave pulse signals during long-distance propagation and ensuring that the stress wave pulse signals can be effectively collected. Thus, it effectively solves the dilemma that in the prior art, stress wave pulse signals are only generated at one end of the anchor cable, and it is difficult to apply the method of stress wave reflection to the effective detection of the anchoring quality of long prestressed anchor cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an assembly structure diagram of the positioning ring and the steel strand in the anchor cable.

[0018] Figure 2 It is a structure diagram of the anchor cable fixed in the slope.

[0019] Figure 3 It is an overall structure diagram of the detection device.

[0020] Figure 4 It is an assembly structure diagram of the locking member and the steel strand.

[0021] Figure 5 It is an exploded view structure diagram of the locking device.

[0022] Figure 6 It is an assembly structure diagram of the sleeve assembly and the steel strand.

[0023] Figure 7 It is an exploded longitudinal sectional view structure diagram of the sleeve assembly.

[0024] Figure 8 It is an exploded view structure diagram of the knocking hammer.

[0025] Figure 9 It is a front view after the knocking hammer is assembled into the hollow sleeve.

[0026] Figure 10 It is Figure 9 The partial enlarged view of part A in

[0027] Figure 11 It is the schematic diagram of the magnetization circuit control.

[0028] Reference numerals: positioning ring 1, steel strand 2, stress wave excitation device 3, locking device 31, rubber sleeve 311, semi-circular housing 312, flange 313, bolt 314, external thread 315, sleeve assembly 32, left end cover assembly 321, connecting ring 3211, limiting plate 3212, stress wave sensor 3213, first spring 3214, internal thread 3215, hollow sleeve 322, circular tube 3221, square tube 3222, right end cover 323, second spring 3231, push block 3232, knocking hammer 33, protective housing 331, ball 3311, iron core 332, conical knocking part 3321, power supply positive connection piece 41, power supply negative connection piece 42, coil first end connection piece 43, coil second end connection piece 44, coil 45, first photoelectric sensor 46, second photoelectric sensor 47, electromagnetic relay 48, permanent magnet 5, slope 9. Specific embodiments

[0029] Please refer to Figures 1-3 , a slope prestressed anchor cable anchoring quality detection device provided by the present invention, includes an anchor cable composed of at least one positioning ring 1 and a plurality of steel strands 2 arranged in parallel through the positioning ring 1, and stress wave excitation devices 3 are connected to both ends of at least one steel strand 2.

[0030] Taking the subgrade slope 9 project of a certain expressway as an example, the designed slope height of the slope 9 is 20 m, the slope angle is 40°, the slope 9 is composed of crushed stone soil, and the natural unit weight γ = 19.2 kN / m 3 , the cohesion c = 28.5 kPa, the internal friction angle φ= 38.9°. Meanwhile, there is a weak interlayer developed inside the slope 9, and the dip direction of the weak interlayer is the same as that of the slope 9, with a dip angle of 56°. Its natural unit weight γ = 19.2 kN / m 3 , cohesion c = 3.8 kPa, and the internal friction angle φ = 21.2°. According to the provisions of the Technical Code for Building Slope Engineering (GB50330 - 2013), combined with the actual needs of the project, two-thirds of the prestressed anchor cables of the slope 9 are selected for quality inspection. The distribution positions of the prestressed anchor cables to be inspected are selected according to the design requirements, and according to the provisions of the Technical Specification for Anchor Bolt Detection and Monitoring (JGJT401 - 2017), the stress wave frequency required for detection and the sensitivity of the stress wave sensor are determined, and then a suitable stress wave excitation device 3 is selected and matched. During construction, the first end of the anchor cable in the detection device together with the stress wave excitation device 3 at the first end is inserted into the deep geotechnical layer of the slope 9, and cement mortar is injected and compacted and fixed to construct the anchorage section of the anchor cable. The second end of the anchor cable is buried in the shallow geotechnical layer of the slope 9 to construct the free section of the anchor cable. The end of the free section and its stress wave excitation device 3 are fixed on the slope surface of the slope 9 through a locking device, so that the anchor cable has prestress.

[0031] Please refer to Figures 3-5 [[ID=!13]]As shown in the figure, the stress wave excitation device 3 further includes a locking member 31, a sleeve assembly 32 and a hammer 33. The locking member 31 is of a cylindrical structure, with a length dimension of 45 mm to 55 mm and an outer diameter dimension of 30 mm to 35 mm. The locking member 31 includes a rubber sleeve 311 and two semi-cylindrical shells 312. The two semi-cylindrical shells 312 are made of aluminum material. On the outer wall of the open ends of the two semi-cylindrical shells 312, flanges 313 are arranged along their length directions. The length of the flange 313 is less than four-fifths of the length of the semi-cylindrical shell 312. Bolt holes are arranged on the flange 313. The two semi-cylindrical shells 312 are connected into a cylinder through bolts 314. The rubber sleeve 311 is placed inside the two semi-cylindrical shells 312. The circumferential side wall of the end of the steel strand 2 is covered by the rubber sleeve 311 and is locked and fixed together under the locking force of the bolt 314. The thickness of the rubber sleeve 311 is from 3 mm to 6 mm, and the inner diameter dimension is from 16 m to 22 mm. The size of the rubber sleeve 311 is selected according to the actual diameter size of the steel strand 2 to ensure that the locking assembly can tightly fit on the steel strand 2. At the same time, it blocks the cement mortar from entering the inside of the stress wave excitation device 3 during the grouting of the anchorage section.

[0032] Please refer to Figure 6 As shown in the figure, the overall length dimension of the sleeve assembly 32 is 115 mm to 125 mm, and it includes a left end cover assembly 321, a hollow sleeve 322 and a right end cover 323 which are connected in sequence.

[0033] Please refer to It should be noted that there may be some inaccuracies in the translation due to the complexity of the technical content. It is recommended to cross-check with relevant professionals for more accurate understanding.Figures 7-8 , the left end cover assembly 321 further includes a connecting ring 3211 and a limiting plate 3212. The first end of the connecting ring 3211 is provided with an internal thread 3215, and the two semi-circular shells 312 of the locking member 31 are provided with external threads 315 within one-fifth of their lengths. The first end of the connecting ring 3211 and the two semi-circular shells 312 are connected and fixed together through the internal thread 3215 and the external thread 315. With this detachable connection structure, the stress wave excitation device 3 at the end of the free section can connect the sleeve assembly 32 and the hammer 33 to the locking member 31 only when detection is required. When detection is not required, the sleeve assembly 32 together with the hammer 33 can be detached from the locking member 31 for recycling, thereby reducing the maintenance cost of the stress wave excitation device 3. The limiting plate 3212 is fixed at the end of the second end of the connecting ring 3211. A through hole is provided on the limiting plate 3212, and a stress wave sensor 3213 is arranged inside the connecting ring 3211. The stress wave sensor 3213 is connected to the limiting plate 3212 through a first spring 3214. The stress wave sensor 3213 is connected to the upper computer. An avoidance through hole communicating with the through hole is provided on the stress wave sensor 3213. Under the elastic force of the first spring 3214, a part of the end face of the steel strand 2 is in close contact with the stress wave sensor 3213, for receiving the stress wave pulse signal and sending the stress wave pulse signal to the upper computer, and another part of the end face of the steel strand 2 faces the avoidance through hole.

[0034] The hollow sleeve 322 includes a round tube 3221 and a square tube 3222. The square tube 3222 is placed inside the round tube 3221, and the outer wall of the square tube 3222 and the inner wall of the round tube 3221 are connected as a whole through a web plate. The hammer 33 is slidably arranged inside the square tube 3222 along the length direction of the square tube 3222. The hammer 33 includes a protective shell 331 and an iron core 332. The protective shell 331 covers the outer wall of the iron core 332. The end of the iron core 332 facing the limiting plate 3212 has a conical knocking part 3321 protruding from the protective shell 331. A number of freely rolling balls 3311 are embedded on the outer wall of the protective shell 331. The balls 3311 are in rolling contact with the inner wall of the square tube 3222, for the rolling and support of the hammer 33 inside the square tube 3222, ensuring that the hammer 33 slides linearly inside the square tube 3222 without deviation. A magnetization circuit is arranged inside the hollow sleeve 322. The magnetization circuit is connected to an external controller. Please refer to Figures 7-10, the magnetization circuit includes a power supply VCC, a power supply positive connection piece 41, a power supply negative connection piece 42, a coil first-end connection piece 43, a coil second-end connection piece 44, and a coil 45. The power supply VCC is arranged on the square tube 3222. The power supply positive connection piece 41 and the power supply negative connection piece 42 are both arranged on the inner wall of the square tube 3222 along the length direction of the square tube 3222 and are respectively connected to the positive and negative poles of the power supply VCC. The coil 45 is wound around the iron core 332. The coil first-end connection piece 43 and the coil second-end connection piece 44 are arranged on the outer wall of the protective housing 331 and are respectively connected to both ends of the coil 45. The power supply positive connection piece 41 is in sliding contact with the coil first-end connection piece 43, and the power supply negative connection piece 42 is in sliding contact with the coil second-end connection piece 44 to form an electrical conduction loop, so that the magnetization circuit can be remotely controlled by an external controller to magnetize or demagnetize the hammer 33. The power supply positive connection piece 41 and the power supply negative connection piece 42 are elastic pieces, so that the power supply positive connection piece 41 and the coil first-end connection piece 43 always maintain sliding contact without breaking the circuit, and the power supply negative connection piece 42 and the coil second-end connection piece 44 also always maintain sliding contact without breaking the circuit. Two power supply positive connection pieces 41, two power supply negative connection pieces 42, two coil first-end connection pieces 43, and two coil second-end connection pieces 44 are respectively arranged to further ensure sliding contact without breaking the circuit.

[0035] Four permanent magnets 5 are arranged on both the limiting plate 3212 of the left end cover assembly 321 and the right end cover 323. The outer wall of the square tube 3222 and the inner wall of the circular tube 3221 are just separated into four accommodating cavities by the radial plates. The four permanent magnets 5 are respectively inserted into the four accommodating cavities, making the overall structure of the sleeve assembly 32 simpler and more compact. The permanent magnets 5 on the limiting plate 3212 and the permanent magnets 5 on the right end cover 323 are arranged with the same-sex magnetic poles facing each other. The magnetic pole of the hammer 33 after being magnetized by the magnetization circuit and the permanent magnet 5 on the limiting plate 3212 are in a state of the same-sex magnetic repulsion, and the magnetic pole of the hammer 33 after being magnetized by the magnetization circuit and the permanent magnet 5 on the right end cover 323 are in a state of opposite-sex magnetic attraction. With such a setting, after the hammer 33 is magnetized by the magnetization circuit, it can quickly slide towards the right end cover 323 under the repulsive force of the permanent magnet 5 on the limiting plate 3212 and the attractive force of the permanent magnet 5 on the right end cover 323.

[0036] The right end cover 323 is connected to the circular tube 3221 and the square tube 3222. An elastic excitation member is provided on the right end cover 323. The elastic excitation member includes a second spring 3231 and a push block 3232. The first end of the second spring 3231 is connected to the right end cover 323, and the second end of the second spring 3231 extends into the square tube 3222 and is connected to the push block 3232. When the hammer 33 is magnetized, the hammer 33 slides towards the right end cover 323 under the magnetic force of the permanent magnet 5 and compresses the second spring 3231. When the hammer 33 is demagnetized, the hammer 33 moves towards the left end cover assembly 321 under the restoring force of the second spring 3231. The conical knocking portion 3321 of the hammer 33 passes through the through hole of the limiting plate 3212 and the avoidance through hole of the stress wave sensor 3213 to strike the end face of the steel strand 2, thereby generating a stress wave pulse signal. The limiting plate 3212 has the function of installing the permanent magnet 5 on the one hand and limiting the movement stroke of the hammer 33 on the other hand.

[0037] Please refer to Figure 7 and Figure 11, in the embodiment of the present invention, the magnetization circuit further includes a first photoelectric sensor 46, a second photoelectric sensor 47, a first one-way thyristor SCR1, an electromagnetic relay 48, a current-limiting resistor R1, a second one-way thyristor SCR2, and a current-limiting resistor R2. The first photoelectric sensor 46 is disposed on the inner wall of the square tube 3222 near the end face of the steel strand 2, and the second photoelectric sensor 47 is disposed on the inner wall of the square tube 3222 near the right end cover 323. The positive terminal of the photoresistor in the first photoelectric sensor 46 is connected to the positive electrode of the power supply VCC through a pull-up resistor R3, and the negative terminal of the photoresistor in the first photoelectric sensor 46 is connected to the negative electrode of the power supply VCC. The base of the triode in the first photoelectric sensor 46 is connected to the photoresistor in the first photoelectric sensor 46 through an optical path. The collector of the triode in the first photoelectric sensor 46 is connected to the positive electrode of the power supply VCC through a pull-up resistor R4, and the emitter of the first photoelectric sensor 46 is connected to the negative electrode of the power supply VCC. The anode of the first one-way thyristor SCR1 is connected to the positive electrode of the power supply VCC, the cathode of the first one-way thyristor SCR1 is connected to the positive electrode of the electromagnetic relay 48, and the negative electrode of the electromagnetic relay 48 is connected to the negative electrode of the power supply VCC. The gate of the first one-way thyristor SCR1 is connected between the pull-up resistor R4 and the collector of the triode in the first photoelectric sensor 46. The fixed end of the armature in the electromagnetic relay 48 is connected to the negative electrode of the power supply VCC through a current-limiting resistor R1, and the moving end of the armature in the electromagnetic relay 48 is in normally closed contact with the coil second-end connecting piece 44. The positive terminal of the photoresistor in the second photoelectric sensor 47 is connected to the gate of the first one-way thyristor SCR1 through a pull-up resistor R6, and the negative terminal of the photoresistor in the first photoelectric sensor 46 is connected to the negative electrode of the power supply VCC. The base of the triode in the first photoelectric sensor 46 is connected to the photoresistor in the second photoelectric sensor 47 through an optical path. The collector of the triode in the second photoelectric sensor 47 is connected to the gate of the first one-way thyristor SCR1 through a pull-up resistor R5, and the emitter of the second photoelectric sensor 47 is connected to the negative electrode of the power supply VCC. The anode of the second one-way thyristor SCR2 is connected to the coil second-end connecting piece 44, the cathode of the second one-way thyristor SCR2 is connected to the negative electrode of the power supply VCC through a current-limiting resistor R2, and the gate of the second one-way thyristor SCR2 is connected between the pull-up resistor R5 and the collector of the triode in the second photoelectric sensor 47. Among them, the resistance value of the current-limiting resistor R2 is greater than the resistance value of the current-limiting resistor R1.

[0038] By introducing the first photoelectric sensor 46, the second photoelectric sensor 47, the first one-way thyristor SCR1, the electromagnetic relay 48, the current-limiting resistor R1, the second one-way thyristor SCR2, and the current-limiting resistor R2 into the magnetization circuit and designing the circuit according to the above connection method, the magnetization and demagnetization of the knocking hammer 33 can be automatically controlled after the magnetization circuit is turned on.

[0039] The specific control principle is as follows: The power supplies VCC in the magnetization circuits of the two stress wave excitation devices 3 are remotely controlled by an external controller to be turned on simultaneously. At this time, only the abc branch formed by the coil 45 and the current-limiting resistor R1 and the second photoelectric sensor 47 in the magnetization circuit are turned on, and the first silicon-controlled rectifier SCR1 will not be turned on. The loop formed by the coil 45 and the current-limiting resistor R1 makes the current value flowing through the coil 45 relatively large. After the iron core 332 is magnetized, a relatively large magnetic field is formed, so that the percussion hammer 33 can slide rapidly towards the right end cover 323 under the magnetic force of the permanent magnet 5. In addition, if the installation direction of the stress wave excitation device 3 is such that the conical percussion part 3321 of the percussion hammer 33 faces the same direction as the gravity direction, the percussion hammer 33 may block the first photoelectric sensor 46 just when the power supply VCC is turned on, which will cause the magnetization circuit not to operate in the set manner. Therefore, when the power supply VCC of the magnetization circuit is just turned on, the first photoelectric sensor 46 cannot be set to the conductive state to prevent the first photoelectric sensor 46 from interfering with the entire magnetization circuit. The magnetization circuit in this embodiment cleverly solves this problem.

[0040] When the percussion hammer 33 slides towards the right end cover 323 under the magnetic force of the permanent magnet 5 and compresses the second spring 3231 of the elastic excitation member in place, the percussion hammer 33 blocks the optical path of the second photoelectric sensor 47. A small current will enter the gate of the first silicon-controlled rectifier SCR1 in the magnetization circuit, thereby turning on the electromagnetic relay 48 and the first photoelectric sensor 46. After the electromagnetic relay 48 is turned on, the moving end of the armature in the electromagnetic relay 48 is disconnected from the coil second end connection piece 44, causing the coil 45 to be open-circuited, that is, the branch abc in the magnetization circuit is open-circuited. At the same time, the silicon-controlled rectifier SCR2 is not turned on yet, so the branch abd is also in an open-circuited state. At this time, the percussion hammer 33 is demagnetized and moves towards the limit plate 3212 under the thrust of the elastic excitation member, hitting the end face of the steel strand 2 to generate a stress wave pulse signal. The percussion hammers 33 of the two stress wave excitation devices 3 simultaneously strike both ends of the anchor cable under the action of their respective elastic excitation members, and stress wave pulse signals are simultaneously excited at both ends of the anchor cable. The stress wave sensor 3213 sends the stress wave pulse signal to the upper computer for analyzing the anchoring quality of the anchor cable.

[0041] After the impact hammer 33 strikes the end face of the steel strand 2 to generate a stress wave pulse signal, the impact hammer 33 blocks the optical path of the first optoelectronic sensor 46. Subsequently, a small current will enter the gate of the second unilateral thyristor SCR2. Then, the branch circuit abd in the magnetization circuit will continuously flow in current, magnetizing the impact hammer 33 again to prevent the impact hammer 33 from colliding with the end face of the steel strand 2 for the second time. Since the resistance value of the current-limiting resistor R2 in the branch circuit abd is greater than that of the current-limiting resistor R1, the magnetic field formed by the impact hammer 33 magnetized by the branch circuit abd is smaller than the magnetic field formed by the impact hammer 33 magnetized by the branch circuit abc. This makes the impact hammer 33 only move to a certain safe distance from the end face of the steel strand 2, rather than compressing the second spring 3231 or being insufficient to compress the second spring 3231 to trigger the branch circuit abd to open and demagnetize the impact hammer 33. After the detection is completed, disconnect the power supply VCC to start a new round of detection.

[0042] It should be noted that in other embodiments of the present invention, it is not necessary to provide permanent magnets 5 on both the limit plate 3212 and the right end cover 323. Instead, it is only necessary to provide a permanent magnet 5 on either the limit plate 3212 or the right end cover � As long as it is ensured that after the impact hammer 33 is magnetized by the magnetization circuit, the impact hammer 33 slides towards the right end cover 323 under the magnetic force of the permanent magnet 5 and compresses the second spring 3231 to a specified position.

[0043] It should be noted that in other embodiments of the present invention, the stress wave sensors 3213 of the stress wave excitation devices 3 of all the anchor cables on the slope 9 can be connected to the upper computer, and the magnetization circuits of all the anchor cables on the slope 9 can be connected to an external controller, so as to carry out large-scale fully automatic and unmanned detection of the anchoring quality of prestressed anchor cables.

[0044] In this embodiment, considering that the stress wave excitation device 3 on one side of the anchorage section of the anchor cable needs to be buried deep in the internal of deep rock and soil for a long time, in order to reduce the detection cost, the stress wave sensor 3213 and the first spring 3214 are not configured in the stress wave excitation device 3 of the anchorage section. A part of the end face of the steel strand 2 is directly in close contact with the limit plate 3212, and another part of the end face of the steel strand 2 faces the through hole on the limit plate 3212.

[0045] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions and substitutions can still be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A device for detecting the anchoring quality of prestressed anchor cables on slopes, characterized in that, An anchor cable includes a positioning ring (1) and several steel strands (2) parallelly passing through the positioning ring (1). Stress wave excitation devices (3) are connected to both ends of at least one of the steel strands (2). The stress wave excitation device (3) includes a locking member (31), a sleeve assembly (32) and a hammer (33). The end of the steel strand (2) is fixed inside the locking member (31). The sleeve assembly (32) further includes a left end cover assembly (321), a hollow sleeve (322) and a right end cover (323) connected in sequence. The locking member (31) is connected to the left end cover assembly (321). The left end cover assembly (321) is provided with a through hole communicating with the hollow sleeve (322). A stress wave sensor (3213) is arranged inside the left end cover assembly (321). The stress wave sensor (3213) is connected to a host computer. An avoidance through hole communicating with the through hole is provided on the stress wave sensor (3213). A part of the end face of the steel strand (2) is attached to the stress wave sensor (3213) for receiving stress wave pulse signals and sending the stress wave pulse signals to the host computer. Another part of the end face of the steel strand (2) faces the avoidance through hole. The hammer (33) is slidably arranged inside the hollow sleeve (322). A magnetization circuit is arranged inside the hollow sleeve (322). The magnetization circuit is connected to an external controller for remotely controlling the magnetization circuit to magnetize or demagnetize the hammer (33). A permanent magnet (5) is arranged on the left end cover assembly (321) and / or the right end cover (323). An elastic excitation member is arranged on the right end cover (323). When the hammer (33) is magnetized, the hammer (33) slides towards the right end cover (323) under the magnetic force of the permanent magnet (5) and compresses the elastic excitation member. When the hammer (33) is demagnetized, the hammer (33) moves towards the left end cover assembly (321) under the restoring force of the elastic excitation member. A part of the hammer (33) passes through the through hole and the avoidance through hole to impact the end face of the steel strand (2), thereby generating stress wave pulse signals. The hollow sleeve (322) includes a circular tube (3221) and a square tube (3222). The square tube (3222) is disposed inside the circular tube (3221), and the outer wall of the square tube (3222) is integrally connected to the inner wall of the circular tube (3221) through radial plates. The knocking hammer (33) is slidably disposed in the square tube (3222) along the length direction of the square tube (3222). The knocking hammer (33) includes a protective shell (331) and an iron core (332). The protective shell (331) covers the outer wall of the iron core (332). The iron core (332) has a conical knocking portion (3321) protruding from the protective shell (331). The magnetization circuit includes a power supply VCC, a power supply positive connection piece (41), a power supply negative connection piece (42), a coil first end connection piece (43), a coil second end connection piece (44), and a coil (45). The power supply VCC is disposed on the square tube (3222). The power supply positive connection piece (41) and the power supply negative connection piece (42) are both disposed on the inner wall of the square tube (3222) along the length direction of the square tube (3222) and are respectively connected to the positive and negative poles of the power supply VCC. The coil (45) is wound around the iron core (332). The coil first end connection piece (43) and the coil second end connection piece (44) are disposed on the outer wall of the protective shell (331) and are respectively connected to both ends of the coil (45). The power supply positive connection piece (41) is in sliding contact with the coil first end connection piece (43), and the power supply negative connection piece (42) is in sliding contact with the coil second end connection piece (44) to form a conductive loop. The magnetization circuit further includes a first photoelectric sensor (46), a second photoelectric sensor (47), a first one-way thyristor SCR1, an electromagnetic relay (48), a current-limiting resistor R1, a second one-way thyristor SCR2, and a current-limiting resistor R2. In the magnetization circuit, the coil (45) and the current-limiting resistor R1 form an abc branch, and the coil (45), the second one-way thyristor SCR2, and the current-limiting resistor R2 form an abd branch. In the magnetization circuit, the resistance value of the current-limiting resistor R2 in the branch abd is greater than that of the current-limiting resistor R1. Therefore, the magnetic field formed by the knocking hammer (33) magnetized by the branch abd is smaller than the magnetic field formed by the knocking hammer (33) magnetized by the branch abc, so that the knocking hammer (33) will only move to a certain safe distance from the end face of the steel strand (2). That is, when the knocking hammer (33) is magnetized again, it can prevent the knocking hammer (33) from colliding with the end face of the steel strand (2) for the second time.

2. The slope prestressed anchor cable anchoring quality detection device according to claim 1, characterized in that, The locking member (31) has a cylindrical structure and includes a rubber sleeve (311) and two semi-cylindrical shells (312). The two semi-cylindrical shells (312) are connected to form a cylinder, and the rubber sleeve (311) is placed inside the two semi-cylindrical shells (312) for covering the peripheral side wall of the end of the steel strand (2). The two semi-cylindrical shells (312) are connected by bolts (314) to lock and fix the steel strand (2) together with the rubber sleeve (311).

3. The slope prestressed anchor cable anchoring quality detection device according to claim 2, characterized in that The left end cover assembly (321) includes a connecting ring (3211) and a limiting plate (3212). The first end of the connecting ring (3211) is provided with an internal thread (3215), and the semi-cylindrical shell (312) is provided with an external thread (315). The first end of the connecting ring (3211) and the semi-cylindrical shell (312) are connected through the internal thread (3215) and the external thread (315). The limiting plate (3212) is fixed at the end of the second end of the connecting ring (3211). The through hole is provided on the limiting plate (3212). The stress wave sensor (3213) is connected to the limiting plate (3212) through a first spring (3214) to ensure that a part of the end face of the steel strand (2) is in close contact with the stress wave sensor (3213). The permanent magnet (5) on the left end cover assembly (321) is fixed on the limiting plate (3212).

4. The slope prestressed anchor cable anchoring quality detection device according to claim 1, characterized in that Two coil first-end connecting pieces (43) and two coil second-end connecting pieces (44) are respectively provided to further ensure sliding contact without open circuit.

5. The slope prestressed anchor cable anchoring quality detection device according to claim 4, characterized in that A number of freely rolling balls (3311) are embedded in the outer wall of the protective shell (331), and the balls (3311) are in rolling contact with the inner wall of the square tube (3222).

6. The slope prestressed anchor cable anchoring quality detection device according to claim 4, characterized in that, The power supply positive connecting piece (41) and the power supply negative connecting piece (42) are elastic pieces.

7. The slope prestressed anchor cable anchorage quality detection device according to claim 4, characterized in that, The first photoelectric sensor (46) is arranged on the inner wall of the square tube (3222) close to the end face of the stranded wire (2), and the second photoelectric sensor (47) is arranged on the inner wall of the square tube (3222) close to the right end cover (323); the positive terminal of the photosensitive resistor in the first photoelectric sensor (46) is connected to the positive pole of the power supply VCC through a pull-up resistor R3, and the negative terminal of the photosensitive resistor in the first photoelectric sensor (46) is connected to the negative pole of the power supply VCC; the base of the triode in the first photoelectric sensor (46) is connected to the photosensitive resistor in the first photoelectric sensor (46) through an optical path, the collector of the triode in the first photoelectric sensor (46) is connected to the positive pole of the power supply VCC through a pull-up resistor R4, and the emitter in the first photoelectric sensor (46) is connected to the negative pole of the power supply VCC; the anode of the first unidirectional thyristor SCR1 is connected to the positive pole of the power supply VCC, the cathode of the first unidirectional thyristor SCR1 is connected to the positive pole of the electromagnetic relay (48), the negative pole of the electromagnetic relay (48) is connected to the negative pole of the power supply VCC, and the gate of the first unidirectional thyristor SCR1 is connected between the pull-up resistor R4 and the collector of the triode in the first photoelectric sensor (46); the fixed end of the armature in the electromagnetic relay (48) is connected to the negative pole of the power supply VCC through a current-limiting resistor R1, and the moving end of the armature in the electromagnetic relay (48) is in normally-closed contact with the coil second-end connecting piece (44); the positive terminal of the photosensitive resistor in the second photoelectric sensor (47) is connected to the gate of the first unidirectional thyristor SCR1 through a pull-up resistor R6, and the negative terminal of the photosensitive resistor in the first photoelectric sensor (46) is connected to the negative pole of the power supply VCC; the base of the triode in the first photoelectric sensor (46) is connected to the photosensitive resistor in the second photoelectric sensor (47) through an optical path, the collector of the triode in the second photoelectric sensor (47) is connected to the gate of the first unidirectional thyristor SCR1 through a pull-up resistor R5, and the emitter in the second photoelectric sensor (47) is connected to the negative pole of the power supply VCC; the anode of the second unidirectional thyristor SCR2 is connected to the coil second-end connecting piece (44), the cathode of the second unidirectional thyristor SCR2 is connected to the negative pole of the power supply VCC through a current-limiting resistor R2, and the gate of the second unidirectional thyristor SCR2 is connected between the pull-up resistor R5 and the collector of the triode in the second photoelectric sensor (47); wherein, the resistance value of the current-limiting resistor R2 is greater than that of the current-limiting resistor R1.

8. The slope prestressed anchor cable anchorage quality detection device according to claim 4, characterized in that The right end cover (323) is connected to the circular tube (3221) and the square tube (3222), and the elastic excitation member includes a second spring (3231) and a push block (3232). The first end of the second spring (3231) is connected to the right end cover (323), and the second end of the second spring (3231) extends into the square tube (3222) and is connected to the push block (3232).

9. A method for detecting the anchoring quality of prestressed anchor cables on slopes, characterized in that, During construction, the first end of the anchor cable in the detection device according to any one of claims 1 to 8, together with the stress wave excitation device (3) at the first end, is inserted into the deep rock and soil of the slope (9), and cement mortar is injected for dense fixation to construct the anchorage section of the anchor cable. The second end of the anchor cable is buried into the shallow rock and soil of the slope (9) to construct the free section of the anchor cable. The end of the free section and its stress wave excitation device (3) are fixed on the slope surface of the slope (9) through a locking device, so that the anchor cable has prestress. During detection, the magnetization circuits of the two stress wave excitation devices (3) are remotely controlled by an external controller to magnetize their respective percussion hammers (33), so that the percussion hammers (33) compress the elastic excitation members under the magnetic force of the permanent magnet (5). Then, the magnetization circuits of the two stress wave excitation devices (3) are simultaneously disconnected to demagnetize the percussion hammers (33). The two percussion hammers (33) simultaneously strike both ends of the anchor cable under the action of their respective elastic excitation members, and stress wave pulse signals are simultaneously excited at both ends of the anchor cable. The stress wave sensor (3213) sends the stress wave pulse signals to the upper computer for analyzing the anchorage quality of the anchor cable.

10. The method for detecting the anchoring quality of prestressed anchor cables on slopes according to claim 9, characterized in that, A stress wave sensor (3213) is not arranged in the stress wave excitation device (3) of the anchorage section.

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