CN115752829A - Anchor cable stress monitoring device and method - Google Patents
Anchor cable stress monitoring device and method Download PDFInfo
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- CN115752829A CN115752829A CN202211482258.0A CN202211482258A CN115752829A CN 115752829 A CN115752829 A CN 115752829A CN 202211482258 A CN202211482258 A CN 202211482258A CN 115752829 A CN115752829 A CN 115752829A
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Abstract
The invention discloses an anchor cable stress monitoring device and method, which belong to the technical field of in-situ test and construction of coastal deep foundation pit engineering, and comprise a plurality of positioning brackets which are arranged at intervals along the length of an anchor cable, wherein the middle part of each positioning bracket is provided with a hole for a grouting pipe to pass through; the anchor cable comprises a plurality of steel strands, a plurality of resistance type strain gauges are arranged on the surface of any steel strand, the resistance type strain gauges are connected with resistance type strain gauge shielding wires, the resistance type strain gauge shielding wires are connected with a static strain acquisition instrument, and the static strain acquisition instrument is connected with an upper computer. The device mainly adopts the mode of implanting resistance-type foil gage on the anchor rope, can monitor the transmission law of the change condition and the axle power of anchor rope stress along with foundation ditch excavation comprehensively.
Description
Technical Field
The invention belongs to the technical field of in-situ test and construction of coastal deep foundation pit engineering, and particularly relates to an anchor cable stress monitoring device and method.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
In recent years, the prestressed anchor cable has the advantages of effectively reducing deformation of strata and buildings, relieving surface subsidence, advancing deformation time points of soil bodies around a foundation pit, avoiding arranging an inner support inside the foundation pit and the like due to small disturbance on an undisturbed soil body, and has obvious economic benefit compared with a traditional deep foundation pit inner support supporting mode. When the deep foundation pit is constructed, the prestressed anchor cable and the support pile (wall) are combined to form a powerful support system, so that the influence of foundation pit excavation on the existing surrounding buildings and environment can be reduced while the earthwork displacement and settlement are reduced. The construction technology of the prestressed anchor cable at the present stage is widely applied to various projects, and particularly has remarkable effects on the aspects of side slopes, underground caverns, deep foundation pit supports and the like.
In order to master the change condition of the stress of the prestressed anchor cable along the anchoring depth direction, analyze the stress characteristics, the change rule, the bearing mechanism and the interface bonding characteristics of the prestressed anchor cable, ensure the construction safety and the engineering quality and provide a reference basis for design, the stress of the prestressed anchor cable is very necessary to be monitored in real time in the foundation pit excavation process.
At present, the conventional drawing test is mostly adopted to monitor the stress of a prestressed anchor cable in engineering to determine the ultimate bearing capacity and check whether the stress of the anchor cable meets the design requirements. The anchor cable dynamometer is generally adopted and installed between an anchor head and an anchor base plate, and axial force change and prestress loss of a prestressed anchor cable in the foundation pit excavation process are monitored. Due to the complex condition of the rock-soil body, the stress action direction on the prestressed anchor cable is different from the stress direction monitored by the anchor cable dynamometer, so that the difference exists between the stress test value and the actual value, and the anchor cable dynamometer is damaged seriously to lose the test capability. In addition, the anchor cable dynamometer can only monitor the axial force at the anchor head position, and is difficult to monitor the stress distribution condition of the anchor cable in the depth direction. The stress monitoring means of the prestressed anchor cable is limited by the terrain, rock mass, environment and monitoring tools.
At present, chinese patent ZL201420353667.5 discloses a prestressed anchor cable stress distribution testing arrangement, specifically lays grating sensor between sleeve pipe inner wall and steel strand wires, does not have direct contact between grating sensor and the steel strand wires, can't directly test the stress of anchor cable, and the true atress of anchor cable can not be reflected in the result, influences the reliability of test data, and in addition, grating sensor cost is high, and it has the limitation to promote in the engineering. Chinese patent ZL201520331138.X discloses a sensor for measuring stress of a side slope anchor rod, and the technology sleeves a novel threaded steel pipe on a solid anchor rod, so that direct contact between the sensor and an anchoring body is effectively avoided, and on one hand, the contact surface between a sleeve and the anchoring body is large, so that the bonding effect of an anchor cable and the anchoring body is influenced; on the other hand, the sensor is not subjected to waterproof and moistureproof treatment by the technology, and the sensor is not high in survival rate due to the fact that the sensor is wetted when encountering water and is easy to short circuit. Therefore, a device capable of monitoring the stress of the anchor cable and ensuring reliable monitoring data is urgently needed.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the anchor cable stress monitoring device and the anchor cable stress monitoring method.
In order to achieve the purpose, the invention is realized by the following technical scheme:
in a first aspect, the invention provides an anchor cable stress monitoring device, which comprises a plurality of positioning brackets arranged at intervals along the length of an anchor cable, wherein the middle parts of the positioning brackets are provided with holes for a grouting pipe to pass through; the anchor cable comprises a plurality of steel strands, a plurality of resistance type strain gauges are arranged on the surface of any steel strand, the resistance type strain gauges are connected with resistance type strain gauge shielding wires, the resistance type strain gauge shielding wires are connected with a static strain acquisition instrument, and the static strain acquisition instrument is connected with an upper computer.
As a further technical scheme, a plurality of clamping grooves are formed in the periphery of the positioning support, and the steel strand penetrates through the clamping grooves to be fixedly positioned.
As a further technical scheme, the plurality of resistance type strain gauges are arranged on the surface of the steel strand at intervals, the plurality of resistance type strain gauges are aligned in the longitudinal direction, the wiring ends of the resistance type strain gauges and the resistance type strain gauge shielding wires face the direction of the free end of the anchor rope, and the resistance type strain gauge shielding wires lead to the end of the free end of the anchor rope along the steel strand.
As a further technical scheme, the outer side of the resistance-type strain gauge is provided with a silicon rubber waterproof layer, the steel strand corresponding to the outer side of the resistance-type strain gauge is provided with a PVC pipe steel bar planting adhesive mold, and two ends of the PVC pipe steel bar planting adhesive mold are provided with binding bands for fixation.
As a further technical scheme, the outer side of the silicon rubber waterproof layer is provided with a steel bar planting adhesive protection layer, and the steel bar planting adhesive protection layer completely covers the silicon rubber waterproof layer and the wiring part of the resistance type strain gauge shielding wire.
As a further technical scheme, a PVC wiring pipe is arranged at the leading-out position of the shielding wire of the resistance type strain gauge.
As a further technical scheme, the resistance type strain gauge shielding wire is fixed on a steel stranded wire which is not provided with the resistance type strain gauge through a binding belt.
In a second aspect, the present invention also provides a monitoring method for the anchor cable stress monitoring device, including the following steps:
determining the length of an anchoring section and the length of a free section of the anchor cable, and arranging a resistance type strain gauge on a steel strand of the anchor cable;
leading the resistance type strain gauge shielding wire to the end point of the free end of the anchor cable, and connecting the terminal of the resistance type strain gauge shielding wire with the resistance type strain gauge;
after wiring is finished, uniformly coating silicon rubber on the outer layers of the resistance-type strain gauges and the wires thereof to form a silicon rubber waterproof layer; sleeving a PVC pipe bar-planting glue mold on a measuring point of the steel strand; thick coating the steel strand measuring point by using bar planting glue, and completely covering the resistance type strain gauge and the wiring end;
the method comprises the following steps of protecting a sleeve of a lead-out resistance type strain gauge shielding wire by using a PVC (polyvinyl chloride) wiring pipe, grouting through a grouting pipe after drilling, connecting the resistance type strain gauge shielding wire with a static strain acquisition instrument, connecting the static strain acquisition instrument with an upper computer, recording the micro strain of a steel strand as an initial value before excavation of a foundation pit, and performing data acquisition on subsequent excavation and tensioning according to a monitoring period until the foundation pit is excavated to a designed elevation;
in the excavation process of the foundation pit, acquiring a strain value of a resistance type strain gauge, and solving a stress value of a section to be detected of the steel strand by using the following formula:
in the formula: a: the cross section of the anchor cable; e: the elastic modulus of the anchor cable; epsilon: strain at a measuring point X; d: the diameter of the anchor cable; n: the number of anchor cables in the same drill hole.
As a further technical scheme, after the resistance type strain gauge shielding wire is arranged, resistance detection is carried out on the resistance type strain gauge shielding wire; after the silicon rubber waterproof layer is formed, straightening the resistance type strain gauge shielding wire at the free end of the anchor cable, and fixing the resistance type strain gauge shielding wire on the steel stranded wire without the measuring point by using a binding belt.
As a further technical scheme, before the anchor cable is installed, the end part of the resistance type strain gauge shielding wire is wrapped by a waterproof adhesive tape to be subjected to waterproof and moistureproof treatment; when the anchor cable is installed, one side of the anchoring section of the anchor cable is led into the drill hole; the anchor cable tensioning operation is carried out after the anchor body reaches 70% of the design strength, the anchor cables are alternately tensioned and pretensioned, and the anchor cables are locked according to a preset prestress locking value.
The beneficial effects of the invention are as follows:
according to the monitoring device, the resistance type strain gauge is arranged on the steel strand, so that the stress distribution condition of the prestressed anchor cable in the depth direction can be monitored in real time, and the anchoring mechanism of the prestressed anchor cable can be better researched; the stress monitoring adopts a resistance type sensor consisting of resistance type strain gauges, so that the manufacturing cost is low, and the installation is convenient.
According to the monitoring device, the PVC pipe embedded bar glue mold is arranged at each measuring point, so that the silicon rubber protective layer and the wiring port can be fully bonded with the embedded bar glue to form the embedded bar glue protective layer, the resistance type strain gauge is well protected, damage to the anchor cable in the installation process is reduced, the influence of underground water on a test result can be effectively controlled after the resistance type strain gauge is packaged, and the test data distortion is avoided.
The monitoring device provided by the invention adopts a casing drilling process, can play a role of supporting in a drilling process, can be more suitable for various stratums, particularly for some near-sea soil filling stratums, reduces the settlement of peripheral soil bodies, reduces the disturbance of construction on the peripheral soil layers, and plays a role of protecting the subsequent placement of anchor cables.
The monitoring device has high reliability, low manufacturing cost and real-time performance, can reflect the real service state of the anchor cable, not only can effectively protect the bonding area of the strain gauge, but also can reduce the influence caused by the constructions such as drilling, grouting and the like of a drilling machine, is suitable for various complex stratums such as coastal or coastal strata, and can monitor the stress of the anchor cable in real time; the stress distribution rule of the prestressed anchor cable in the near-sea soil rock deep foundation pit along the depth direction and the change trend along with time can be effectively monitored, and a reliable basis is provided for comprehensively evaluating the stability of the near-sea soil rock deep foundation pit engineering.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
Fig. 1 is a schematic structural diagram of a main body of the anchor cable stress testing device of the present invention;
FIG. 2 is a schematic view of an anchor cable model according to the present invention;
FIG. 3 is a schematic diagram of a protection method of a resistance strain gage according to the present invention;
FIG. 4 is a schematic diagram of the relative positions of the prestressed anchorage cable, the positioning bracket and the casing when the prestressed anchorage cable is installed according to the present invention;
in the figure: the mutual spacing or size is exaggerated to show the position of each part, and the schematic diagram is only used for illustration;
wherein, 1 steel strand wires, 2PVC slip casting pipe, 3 resistance-type foil gage, 4 silicon rubber waterproof layers, 5 bar planting glue protective layers, 6 resistance-type foil gage shielding wires, 7PVC bunch pipe, 8 static strain collection appearance, 9 host computers, 10 locating supports, 11PVC pipe bar planting glue mould, 12 gauzes, 13 ligature area, 14 grout, 15 sleeve pipes.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
In an exemplary embodiment of the present invention, as shown in fig. 1, a cable stress monitoring device is provided, which can be used for stress testing of a prestressed cable in a near-sea filling formation.
The main structure of the monitoring device comprises: steel strand wires 1, PVC slip casting pipe 2, resistance-type foil gage 3, silicon rubber waterproof layer 4, bar planting glue protective layer 5, resistance-type foil gage shielding wire 6, PVC bunch pipe 7, static strain collection appearance 8, host computer 9, locating support 10, PVC pipe bar planting glue mould 11, gauze 12, ligature area 13, grout 14, sleeve pipe 15.
The specification of the steel strand 1 is 15.2mm in diameter, the length is cut according to design paper, and the length of the steel strand is 21m in the embodiment. The prestressed anchor cable adopted by the monitoring device comprises three steel strands 1 with the same specification and is sequentially fixed on a plurality of positioning supports 10, a PVC grouting pipe 2 penetrates through a central hole of each positioning support 10, the length of each PVC grouting pipe 2 is slightly smaller than that of each steel strand 1, and the diameter of each PVC grouting pipe is about 30mm. The positioning brackets 10 are arranged at proper intervals, in this embodiment, the positioning brackets are arranged at intervals of 1.5m, and the positioning brackets 10 corresponding to the free sections of the anchor cables should be separated from the rod body and can slide relatively.
A plurality of clamping grooves are formed in the periphery of the positioning support 10, the steel strands penetrate through the clamping grooves to be fixed and positioned, and one steel strand penetrates through one clamping groove.
16 resistance-type strain gauges 3 need to be arranged on the surface of any steel strand 1 of the prestressed anchor cable, and the 16 resistance-type strain gauges 3 need to be aligned in the longitudinal direction. The type 3 of the resistance type strain gauge adopted in the embodiment is BF120-5AA-P300-D, the resistance value is 119.6 +/-0.3 omega, the survival rate of the resistance type strain gauge needs to be checked by using a universal meter before the resistance type strain gauge is used, and whether the resistance type strain gauge fails in the transportation and carrying processes is checked.
The resistance type strain gauge 3 can be arranged on the steel strand 1 in a sticking mode, a measuring point is polished by using abrasive paper before the resistance type strain gauge 3 is stuck, after the surface is polished to be smooth, the resistance type strain gauge 3 is stuck to the measuring point of the steel strand 1 by using glue, the long side direction of the resistance type strain gauge 3 is consistent with the axis direction of the steel strand 1, the wiring end of the resistance type strain gauge 3 faces to the free end direction of the prestressed anchor cable, and the resistance type strain gauge 3 and the resistance type strain gauge shielding wire 6 are conveniently connected and led out; when the resistor type strain gauge is pasted, bubbles on the pasting surface of the resistor type strain gauge 3 need to be extruded, and the next operation can be carried out after the resistor type strain gauge 3 is completely fixed.
The resistance type strain gage shielding wire 6 adopts a flame-retardant polyvinyl chloride shielding signal wire with two cores, 0.2m is reserved from the measuring point position to the end position of the free end of the prestressed anchor cable along the lead wire 1, and the rear wiring is convenient. Two wires of each resistance type strain gage 3 are respectively connected with two core wires of the resistance type strain gage shielding wire 6 through an electric adhesive tape, each resistance type strain gage 3 corresponds to one resistance type strain gage shielding wire 6, the length of each resistance type strain gage shielding wire 6 led to the end part of the free end of the prestressed anchor cable is the same, 16 resistance type strain gage shielding wires 6 need to be led out from 16 resistance type strain gages 3, and a binding belt 13 needs to be used between every two measuring points to fix the resistance type strain gage shielding wires 6 on the same steel strand 1 which is not adhered with the resistance type strain gage 3.
The silicone rubber waterproof layer 4 can adopt 704 silicone rubber, after the resistance-type strain gauge 3 is pasted and wired, the outer layer of the silicone rubber waterproof layer is evenly coated with 704 silicone rubber, the silicone rubber waterproof layer 4 is solidified to form, the resistance-type strain gauge 3 and the conducting wire need to be completely covered during coating, and the operation of coating the bar-planting adhesive can be carried out after the coating is finished and the standing is carried out for 12 hours.
The PVC pipe bar planting glue die 11 adopts a PVC hose (the diameter of the PVC hose is 2-3 times of the diameter of the steel strand) with the diameter of about 40mm, the length of the PVC hose is cut by the front edge in the diameter direction to be about 20cm, the resistance-type strain gauge 3 and the lead can be completely covered by the PVC hose, and then the PVC hose is cut along the length direction and sleeved on a measuring point of the steel strand 1. Need to carry out the ligature with ligature area 13 at 11 both ends of PVC pipe bar planting glue mould before paining bar planting glue, prevent that bar planting glue from spilling.
The bar planting glue protective layer 5 is made of bar planting glue, after the silicon rubber waterproof layer 4 is solidified, the outer layer of the bar planting glue protective layer is coated thickly, the wire connection parts of the silicon rubber waterproof layer 4 and the resistance type strain gauge shielding wire 6 need to be completely covered, two layers of gauze 12 are laid for reinforcement before hardening, and the bar planting glue protective layer 5 is obtained after complete hardening.
In the process of pasting the resistance-type strain gauge 3, after relevant steps related to the resistance-type strain gauge 3 are completed, the survival condition of the resistance-type strain gauge needs to be detected by a universal meter, and if the resistance-type strain gauge 3 fails, the resistance-type strain gauge is replaced in time.
The other end of the resistance type strain gauge shielding wire 6 is connected with a static strain acquisition instrument 8; the static strain acquisition instrument 8 is connected with the upper computer 9 to acquire strain data, and whether an initial value of strain is introduced or not should be noticed during data acquisition. In this embodiment, the static strain acquiring instrument 8 is a DH3816N static strain acquiring instrument.
In the embodiment, a steel pipe with the diameter of 160mm and the wall thickness of about 10mm is used as the sleeve 15, and the sleeve 15 needs to be installed on a drilling machine for drilling in sections until the depth is 0.5m below the designed depth before the prestressed anchor cable is installed.
After drilling is finished, arranging the steel strands, the positioning support, the grouting pipes and the like in the drill holes, then grouting into the grouting pipes, adopting cement slurry 14 as the grouting material of the grouting pipes 2, adopting common silicate cement 42.5R as the cement slurry 14, stopping grouting when the grout overflows from the holes during grouting, filling the grout into the holes, and performing grout filling when the grout is hardened and cannot fill the holes. The cement paste 14 coats the steel strand and the positioning bracket in the steel strand and the positioning bracket.
In the whole installation and test process, the connection part of the resistance-type strain gauge 3 and the resistance-type strain gauge shielding wire 6 needs to be prevented from applying force in the leading-out process of the resistance-type strain gauge shielding wire 6, so that the connection part is prevented from being disconnected.
In another exemplary embodiment of the present invention, a monitoring method of the anchor cable stress monitoring device is provided, which includes the following steps:
(1) According to the test scheme, firstly, the length of an anchoring section and the length of a free section of the prestressed anchor cable are determined, wherein the anchoring section of the prestressed anchor cable adopted in the embodiment is 9.0m, and the free section is 12.0m;
(2) Determining the sticking position of the resistance type strain gauge 3 of the test scheme, wherein the resistance type strain gauge is respectively arranged at the positions 0.1m, 1.0m, 2.0m, 3.0m, 4.0m, 4.5m, 5.0m, 5.5m, 6.0m, 6.5m, 7.0m, 7.5m, 8.0m, 8.5m, 9.0m and 15.0m away from the anchoring section of the prestressed anchorage cable, and the sticking position is marked by chalk in the embodiment;
(3) Polishing rust at a preset measuring point of the steel strand 1 by using sand paper, after polishing to be smooth, sticking a resistance type strain gage 3 on the measuring point by using 502 glue, wherein the long side direction of the resistance type strain gage 3 is consistent with the length direction of the steel strand 1, and the lead end of the resistance type strain gage 3 is required to face the direction of the end point of the free section of the prestressed anchor cable; when the resistor type strain gauge is pasted, bubbles on the pasting surface of the resistor type strain gauge 3 need to be extruded, and the next operation can be carried out after the resistor type strain gauge 3 is completely fixed;
(4) One end of the resistance type strain gauge shielding wire 6 is temporarily fixed at each measuring point by using an adhesive tape, so that subsequent wiring is facilitated, the other end of the resistance type strain gauge shielding wire 6 is led to a free end point, the length of about 3m is reserved, so that data collection is facilitated, and the reserved length of each resistance type strain gauge shielding wire 6 needs to be the same. After the 16 lead wires of the resistance type strain gauge shielding wire 6 are finished, labels are respectively pasted at two ends of the resistance type strain gauge shielding wire 6, so that the survival rate of the resistance type strain gauge 3 can be conveniently checked subsequently, and the work of accurately connecting the static strain acquisition instrument 8 is facilitated.
(5) Connecting two poles of two-core copper wires of a wiring end of a resistance-type strain gauge shielding wire 6 temporarily fixed at a measuring point in the step (4) with two poles of a wire of a resistance-type strain gauge 3 respectively, wiring by using an electric adhesive tape, and performing resistance detection on the resistance-type strain gauge shielding wire 6 at the free end of the prestressed anchor cable by using a universal meter so as to detect whether the resistance-type strain gauge 3 fails or the wiring end is broken and timely replaced and wired;
(6) After wiring is finished, uniformly coating 704 silicon rubber on the outer layers of the resistance-type strain gauge 3 and the lead thereof, standing for 12 hours, and curing to form a silicon rubber waterproof layer 4, wherein the resistance-type strain gauge 3 and the lead thereof need to be completely covered during coating;
(7) The steps are completed, the resistance-type strain gauge shielding wire 6 at the free end of the prestressed anchor cable is straightened, the resistance-type strain gauge shielding wire 6 is fixed on one of the steel strands 1 which is not provided with the measuring points by using a binding belt 13, and the resistance-type strain gauge shielding wire 6 is fixed once between every two measuring points so as to prevent the resistance-type strain gauge shielding wire 6 from falling off when the prestressed anchor cable is carried and installed in the follow-up process;
(8) After the silicone rubber waterproof layer 4 is formed, cutting a PVC hose with the diameter of about 40mm to the length of about 20cm along the diameter direction, then cutting the PVC hose along the length direction, sleeving the PVC hose on a measuring point of the steel strand 1 to form a PVC pipe bar planting adhesive mold 11, and binding and fixing two ends of the PVC pipe bar planting adhesive mold 11 by using binding bands 13 before applying bar planting adhesive to prevent the bar planting adhesive from leaking;
(9) Thick coating the measuring point of the steel strand 1 by using bar-planting glue, covering the resistance-type strain gauge 3 and the wiring end completely, coating two layers of gauze 15 before the bar-planting glue is not hardened for reinforcement, and obtaining a bar-planting glue protective layer 5 after the bar-planting glue is completely hardened;
(10) After the bar planting adhesive protection layer 5 is completely formed, the PVC bunching pipe 7 is used for protecting the resistance type strain gauge shielding wire 6 led out from the free end position of the prestressed anchor cable in a sleeving manner, the PVC bunching pipe 7 is fixed on site when the prestressed anchor cable is installed, and the resistance type strain gauge shielding wire 6 is prevented from being damaged in the carrying and installing processes of the prestressed anchor cable;
(11) Determining the drilling position of the prestressed anchor cable in a construction site, adjusting the drilling angle of the anchoring drilling machine according to the terrain and geological conditions, and sleeving a special drill bit tail sleeve on the anchoring drilling machine; firmly connecting the sleeve 15 with a drill bit tail sleeve, sleeving a drill bit at the front end of the first sleeve 15, determining the drilling depth according to geological conditions, splicing the sleeves 15 on site, after one sleeve 15 is drilled, sleeving a connecting sleeve with an artificially-coated lubricant at the tail part of the previous sleeve 15, and then connecting the next sleeve 15 until each sleeve 15 is drilled to the required length;
(12) Before the prestressed anchor cable is installed, the end part of the resistance type strain gage shielding wire 6 is wrapped by a waterproof adhesive tape to carry out waterproof and moistureproof treatment; when the prestressed anchor cable is installed, one side of the anchoring section of the prestressed anchor cable needs to be led into a drill hole by a careful wing, so that the bar planting adhesive protective layer 5 and the resistance type strain gauge shielding wire 6 are prevented from being damaged in the installation process;
(13) After the prestressed anchor indexes a specified depth, the sleeve 15 is led out in sections by using an anchoring drilling machine, grouting is carried out through the PVC grouting pipe 2, the grouting can be stopped when grout overflows from an orifice, the grouting needs to be full, and grout is supplemented when the grout cannot be filled in the full orifice after being hardened;
(14) After the step (13) is completed, assembling the channel steel wale according to design requirements, wherein in the embodiment, 25C channel steel is selected as the steel material, and the wale is installed after the surface layer construction is completed;
(15) Connecting a resistance type strain gauge shielding wire 6 with a static strain acquisition instrument 8, connecting the static strain acquisition instrument 8 with an upper computer 9, recording the micro-strain of the steel strand 1 as an initial value before excavation of the foundation pit, and performing data acquisition on subsequent excavation and tensioning according to a monitoring period until the foundation pit is excavated to a designed elevation;
(16) The prestressed anchor cable tensioning operation can be carried out after the strength of the anchoring body and the waist beam reaches 70% of the designed strength, the prestressed anchor cables are alternately tensioned according to the specification requirement and locked according to the designed prestress locking value; the prestressed anchor cable of the layer is not locked according to the prestress required by the design, and excavation of the next layer of earth and stone is forbidden;
(17) In the foundation ditch excavation process, with the strain value of static strain acquisition instrument 8 and upper computer 9 real-time recording resistance-type foil gage, utilize equation (1) can try to get the sectional stress value that awaits measuring of steel strand wires 1:
in the formula: a: anchor cable cross-sectional area; e: the elastic modulus of the anchor cable; epsilon: strain at a measuring point X; d: the diameter of the anchor cable; n: the number of anchor cables in the same drill hole.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An anchor cable stress monitoring device is characterized by comprising a plurality of positioning brackets which are arranged at intervals along the length of an anchor cable, wherein the middle parts of the positioning brackets are provided with holes for a grouting pipe to pass through; the anchor cable comprises a plurality of steel strands, a plurality of resistance type strain gauges are arranged on the surface of any steel strand, the resistance type strain gauges are connected with resistance type strain gauge shielding wires, the resistance type strain gauge shielding wires are connected with a static strain acquisition instrument, and the static strain acquisition instrument is connected with an upper computer.
2. The cable bolt stress monitoring device of claim 1, wherein the positioning bracket has a plurality of notches formed in its periphery, and the steel strand is passed through the notches to be fixed and positioned.
3. The cable bolt stress monitoring device of claim 1, wherein the plurality of resistive strain gages are spaced apart on the surface of the steel strand, and the plurality of resistive strain gages are longitudinally aligned with the terminal of the resistive strain gage shield wire facing the free end of the cable bolt, and the resistive strain gage shield wire is routed along the steel strand to a position at the end of the free end of the cable bolt.
4. The anchor cable stress monitoring device of claim 1, wherein a waterproof silicone rubber layer is disposed on the outer side of the resistive strain gauge, a PVC tube steel planting glue mold is disposed on the outer side of the steel strand corresponding to the resistive strain gauge, and binding bands are disposed at two ends of the PVC tube steel planting glue mold for fixation.
5. The anchor cable stress monitoring device of claim 4, wherein the silicon rubber waterproof layer is provided with a steel bar planting adhesive protective layer, and the steel bar planting adhesive protective layer completely covers the silicon rubber waterproof layer and the wiring part of the resistance strain gauge shielding wire.
6. The anchor cable stress monitoring device of claim 1, wherein a PVC cable tube is provided at the leading-out position of the resistance strain gauge shielding wire.
7. The anchor cable stress monitoring device of claim 1, wherein the resistive strain gage shielding wire is secured to the steel strand that is not provided with a resistive strain gage by a tie wrap.
8. A method of monitoring anchor cable stress monitoring apparatus as claimed in any one of claims 1 to 7, including the steps of:
determining the length of an anchoring section and the length of a free section of the anchor cable, and arranging a resistance type strain gauge on a steel strand of the anchor cable;
leading the resistance type strain gauge shielding wire to the end point of the free end of the anchor cable, and connecting the terminal of the resistance type strain gauge shielding wire with the resistance type strain gauge;
after wiring is finished, uniformly coating silicon rubber on the outer layers of the resistance-type strain gauges and the wires thereof to form a silicon rubber waterproof layer; sleeving a PVC pipe bar-planting glue mold on a measuring point of the steel strand; thick coating the steel strand measuring point by using bar planting glue, and completely covering the resistance type strain gauge and the wiring end;
the method comprises the following steps of protecting a led-out resistance type strain gage shielding wire by using a PVC (polyvinyl chloride) bundle pipe in a sleeve mode, drilling by adopting a sleeve drilling mode, grouting by using a grouting pipe, connecting the resistance type strain gage shielding wire with a static strain acquisition instrument, connecting the static strain acquisition instrument with an upper computer, recording the micro strain of a steel strand as an initial value before excavation of a foundation pit, and carrying out data acquisition on subsequent excavation and tensioning according to a monitoring period until the foundation pit is excavated to a designed elevation;
in the excavation process of the foundation pit, strain values of the resistance type strain gauges are collected, and the stress value of the section to be measured of the steel strand is obtained by the following formula:
in the formula: a: anchor cable cross-sectional area; e: the elastic modulus of the anchor cable; epsilon: strain at point X; d: the diameter of the anchor cable; n: the number of anchor cables in the same drill hole.
9. The monitoring method according to claim 8, wherein after the resistive strain gauge shield wire is arranged, the resistive strain gauge shield wire is subjected to resistance detection; after the silicone rubber waterproof layer is formed, straightening the resistance-type strain gauge shielding wire at the free end of the anchor cable, and fixing the resistance-type strain gauge shielding wire on the steel stranded wire without measuring points by using a binding belt.
10. The monitoring method according to claim 8, wherein before the anchor cable is installed, the end of the resistance type strain gauge shielding wire is wrapped with a waterproof tape to perform waterproof and moisture-proof treatment; when the anchor cable is installed, one side of the anchoring section of the anchor cable is led into the drill hole; the anchor cable tensioning operation is carried out after the anchor body reaches 70% of the design strength, the anchor cables are alternately tensioned and pretensioned, and the anchor cables are locked according to a preset prestress locking value.
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2248951A1 (en) * | 2009-05-08 | 2010-11-10 | Keller Holding gmbh | Method and device for determining the axial force progression in a pressure-grouted anchor |
| CN104198366A (en) * | 2014-09-01 | 2014-12-10 | 北京科技大学 | Method for monitoring corrosion of steel strand of post-tensioned prestressed concrete structure |
| CN105064356A (en) * | 2015-08-07 | 2015-11-18 | 青岛理工大学 | Prestress compound bar and cable anchoring device for supporting soft and loose soil mass |
| CN204898667U (en) * | 2015-08-07 | 2015-12-23 | 青岛理工大学 | A anchor rope clamping orient device that is used for prestressing force coupled pole cable anchor system |
| CN107991189A (en) * | 2017-12-06 | 2018-05-04 | 东北大学 | A kind of prestressed cable anchorage performance testing device and test method |
| CN211472485U (en) * | 2019-09-27 | 2020-09-11 | 中国二十冶集团有限公司 | Prestressed anchor cable structure for controlling anchor cable deformation and prestress loss |
| CN114062248A (en) * | 2021-11-02 | 2022-02-18 | 西南交通大学 | System and method for testing friction resistance value of free section of rock-soil anchor cable pipeline |
| CN114922174A (en) * | 2022-06-02 | 2022-08-19 | 包钢勘察测绘研究院 | Prestressed anchor cable for detecting underwater coagulation and hardening process of anchoring body and detection method |
| CN115233747A (en) * | 2022-07-13 | 2022-10-25 | 青岛理工大学 | Device and method for testing stress of micro steel pipe pile in miscellaneous filled stratum |
-
2022
- 2022-11-24 CN CN202211482258.0A patent/CN115752829A/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2248951A1 (en) * | 2009-05-08 | 2010-11-10 | Keller Holding gmbh | Method and device for determining the axial force progression in a pressure-grouted anchor |
| CN104198366A (en) * | 2014-09-01 | 2014-12-10 | 北京科技大学 | Method for monitoring corrosion of steel strand of post-tensioned prestressed concrete structure |
| CN105064356A (en) * | 2015-08-07 | 2015-11-18 | 青岛理工大学 | Prestress compound bar and cable anchoring device for supporting soft and loose soil mass |
| CN204898667U (en) * | 2015-08-07 | 2015-12-23 | 青岛理工大学 | A anchor rope clamping orient device that is used for prestressing force coupled pole cable anchor system |
| CN107991189A (en) * | 2017-12-06 | 2018-05-04 | 东北大学 | A kind of prestressed cable anchorage performance testing device and test method |
| CN211472485U (en) * | 2019-09-27 | 2020-09-11 | 中国二十冶集团有限公司 | Prestressed anchor cable structure for controlling anchor cable deformation and prestress loss |
| CN114062248A (en) * | 2021-11-02 | 2022-02-18 | 西南交通大学 | System and method for testing friction resistance value of free section of rock-soil anchor cable pipeline |
| CN114922174A (en) * | 2022-06-02 | 2022-08-19 | 包钢勘察测绘研究院 | Prestressed anchor cable for detecting underwater coagulation and hardening process of anchoring body and detection method |
| CN115233747A (en) * | 2022-07-13 | 2022-10-25 | 青岛理工大学 | Device and method for testing stress of micro steel pipe pile in miscellaneous filled stratum |
Non-Patent Citations (2)
| Title |
|---|
| 刘新荣;刘永权;康景文;杨忠平;: "基坑锚索预应力损失规律及分步张拉控制措施研究", 岩土工程学报, no. 10 * |
| 刘永权;刘新荣;杨忠平;康景文;: "不同类型预应力锚索锚固性能现场试验对比研究", 岩石力学与工程学报, no. 02, 29 February 2016 (2016-02-29), pages 275 - 283 * |
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