CN108844807B - Indoor simulation test method for stress characteristic of fiber rib anti-floating anchor rod - Google Patents
Indoor simulation test method for stress characteristic of fiber rib anti-floating anchor rod Download PDFInfo
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
- G01B7/24—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge using change in magnetic properties
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/10—Measuring force or stress, in general by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
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- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
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Abstract
The invention belongs to the technical field of foundation engineering tests, and relates to an indoor simulation test method for the stress characteristics of a fiber rib anti-floating anchor rod, which is closer to the actual engineering and can quickly and accurately test the anti-pulling bearing capacity and the rod body stress change rule of the fiber rib anti-floating anchor rod, most importantly, the method can simultaneously simulate the anchoring working mechanism with bedrock and the anchoring working mechanism with a foundation slab, namely, a self-compensating fiber grating sensor is arranged on the rod body of the fiber rib anti-floating anchor rod, the other end of the rod body is connected with the foundation slab after the rod body is placed into a reserved grouting hole of the bedrock to be anchored, and an indoor simulation test device is adopted to carry out the anti-pulling bearing capacity and the deformation test of the anti-; the method is simple, convenient to install, strong in operability, safe, reliable, high in testing precision, low in cost and high in reuse rate.
Description
The technical field is as follows:
the invention belongs to the technical field of foundation engineering tests, and relates to an indoor simulation test method for the stress characteristics of a fiber-reinforced anti-floating anchor rod.
Background art:
the fiber bar is a novel material which is formed in one step by taking fiber materials (carbon fibers, glass fibers, aramid fibers, basalt fibers and the like) as reinforcing materials and synthetic resin as a base material, impregnating resin glue solutions such as unsaturated polyester resin containing various auxiliaries such as curing agents, accelerators and the like with fiber yarns, and then performing pultrusion, thread winding and curing. The fiber rib anti-floating anchor rod has the advantages of high tensile strength, light weight, corrosion resistance, electromagnetic interference resistance, high cost performance and the like. In the anti-floating engineering, the fiber reinforced anti-floating anchor rod can overcome the chemical corrosion of ions such as chloride ions and sulfate radicals in underground water on the metal material anti-floating anchor rod in the service process and the electrochemical corrosion of the metal material caused by stray current generated by direct current in urban rail transit construction projects in coastal regions, so that the bearing capacity and the durability of the anti-floating anchor rod are ensured. Meanwhile, as the fiber ribs belong to anisotropic materials, when the fiber ribs are used as the anti-floating anchor rod, the anti-shearing performance is poor, the fiber ribs are not suitable for bending, the workload of a drawing test is large, the consumed time is long, and unnecessary troubles are caused to engineering. Chinese patent 201720304289.5 discloses a drawing test device for anchor rod stress characteristic research, which comprises an anchor rod preparation system and a loading system; the anchor rod preparation system comprises a system frame, a base plate, a first shell and a plurality of second shells, wherein the loading system comprises an axial force loading device and a normal force loading device, the anchor rod preparation and stress test are integrated for the first time, the anchor rod can be prepared firstly and then axial tension is applied to the anchor rod, the stress condition of the anchor rod is analyzed, in the anchor rod drawing test process, controllable normal stress action can be applied to an anchor rod mortar body, the actual axial stress condition of the anchor rod is simulated approximately, so that the related research result of the axial stress characteristic of the anchor rod is more reasonable and applicable, and the design and construction of the anchor rod are better served; 201710052406.8 discloses a test device and a method for testing anchor rod stressometers under different working conditions, the test device comprises a test platform, the upper surface of the test platform is provided with two mutually perpendicular support rails, each support rail is provided with a rolling support, the center of the upper part of the rolling support is provided with a rotating shaft, the top of the rotating shaft is provided with a clamping device, an anchor rod is clamped between the two rolling supports, the middle of the anchor rod is provided with the anchor rod stressometer, two strain gauges and two jacks, and the anchor rod stressometer and the strain gauges are connected with a data acquisition unit through data lines; the method comprises the following steps: (1) installing a test device; (2) installing an anchor rod; (3) fixing the rolling support; (4) installing a data acquisition unit; (5) testing the anchor rod; (6) the principle of the invention is simpler, the stress state of the simulation anchor rod is real, but the accuracy of the measured data is not high in the actual test, and the cost is high; 201420358169.X discloses a test bed for testing comprehensive mechanical properties of an anchor rod, which comprises a propelling and stirring test mechanism, an installation pre-tightening test mechanism, a bending load test mechanism, an axial load test mechanism, a shearing load test mechanism and an impact load test mechanism, wherein the propelling and stirring test mechanism, the installation pre-tightening test mechanism, the bending load test mechanism, the axial load test mechanism, the shearing load test mechanism and the impact load test mechanism are arranged on the installation test bed; the test bed can simulate the installation and working process of the anchor rod in a laboratory, and apply single or multiple combined external forces such as torsion, stretching, bending, shearing, impact and the like to the anchor rod; the anchor rod is loaded by the mutually independent loading systems, so that independent tests of various loads in the anchor rod installation and working process can be respectively carried out, and combined loading tests of several kinds of arbitrary working stress such as stretching, shearing and impact caused by installation stress and surrounding rock deformation can also be carried out, so that the comprehensive mechanical property of the anchor rod under the combined action of various external forces can be effectively tested. Therefore, in order to verify the feasibility of the fiber rib anti-floating anchor rod in engineering application, a reasonable, quick and effective drawing test device is urgently designed, and the device has very important practical significance and theoretical value.
The invention content is as follows:
the invention aims to overcome the defects in the prior art, and provides an indoor simulation test method for the stress characteristics of a fiber rib anti-floating anchor rod on the premise of reducing the test cost and improving the test efficiency, so that the method is closer to the actual engineering, can quickly and accurately test the anti-pulling bearing capacity and the rod body stress change rule of the fiber rib anti-floating anchor rod, and most importantly can simulate the working mechanism of a real anti-floating anchor rod system (simultaneously simulating the anchoring with bedrock and the anchoring with a base bottom plate).
In order to achieve the purpose, the invention is realized in an indoor simulation test device for the stress characteristic of the fiber rib anti-floating anchor rod, and the concrete process is as follows:
(1) preparing a bedrock: firstly, vertically building a template of bedrock, fixing a PVC pipe coated with a release agent on the outer side on the position of a central axis in the template of the bedrock, pouring concrete by adopting the prior art, manufacturing a concrete standard test block under the same condition, taking out the PVC pipe to form a grouting hole before final setting, inserting a fiber bar anti-floating anchor rod body planted with an anchor rod body stressometer into the grouting hole, installing a centering device at the pre-marked position of the fiber bar anti-floating anchor rod body, pouring M30 cement mortar, manufacturing a mortar test block at the same time, curing to the age to form a mortar anchoring body, and detecting the strength of the mortar anchoring body; in the process, the stress meter of the anchor rod body is well protected, and the survival rate of the anchor rod body is ensured to reach 95 percent;
(2) manufacturing a foundation slab: horizontally placing a bed rock with the strength reaching 100% on a supporting platform of a smooth base, sequentially penetrating a second constant-stiffness plate, a jack and a load sensor through a fiber rib anti-floating anchor rod body and installing the second constant-stiffness plate, the jack and the load sensor on the upper surface of a bearing platform, ensuring that the centroids of the second constant-stiffness plate, the jack, the load sensor and the fiber rib anti-floating anchor rod body are in the same straight line, building a template of a foundation slab on the supporting platform, binding a reinforcement cage, fixing the position of the fiber rib anti-floating anchor rod body in the bed rock in the template of the foundation slab, finally pouring concrete to manufacture the foundation slab, manufacturing a concrete standard test block under the same condition, testing the strength of the concrete standard test block, curing the concrete standard test block to the age, determining the relative positions of the foundation slab and the bed rock again before final setting of the concrete standard test block, and ensuring the level;
(3) and mounting a displacement meter: firstly, drilling holes in the positions, which are above the centers of a foundation slab and bedrock, of an electric drill to install expansion bolts and steel plates of a displacement base, then adhering anchor rod rigid wings to corresponding positions by using epoxy resin and curing agent mixed liquid with the mass ratio of 2:1, maintaining for 3 days, adsorbing a magnetic seat on a supporting steel plate after the epoxy resin is completely cured, installing an automatic displacement acquisition meter, finally compressing a telescopic rod of the automatic displacement acquisition meter for a certain distance (ensuring that the telescopic rod can extend for at least 4cm during testing, and considering that the anchor rod is damaged when the displacement exceeds 4 cm), aligning and placing the telescopic rod rigid wings on the anchor rod to ensure that the automatic displacement acquisition meter is horizontal and vertical;
(4) and (3) carrying out a test: the jack and the external hydraulic oil pump are firmly connected by a matched oil pipe, the automatic displacement acquisition meter and the anchor rod body stress meter are respectively connected with a demodulator interface of an external acquisition system, initial reading is recorded, the survival rate of the sensor meets the requirement and then is loaded step by step, test data is recorded, and the test loading, unloading and termination loading conditions and the anchor rod damage judgment standard are executed according to the technical specification for supporting the foundation pit of the building (JGJ 120-2012).
The main structure of the invention comprises a smooth base, a supporting platform, a bearing platform, a foundation slab, bedrock, a grouting hole, a fiber rib anti-floating anchor rod body, an anchor rod body stress meter, a first constant stiffness plate, a second constant stiffness plate, a jack, a load sensor, an automatic displacement acquisition meter, a displacement base, an anchor rod rigid wing and a centering device; the base system is composed of a smooth base and supporting platforms, two supporting platforms are symmetrically arranged on the smooth base, five spherical hinge supports are uniformly welded in the center of the lower surface of each supporting platform along the horizontal direction, a bearing platform is arranged between the two supporting platforms, a foundation slab and a bedrock are respectively arranged on the two supporting platforms, the length of the bedrock is larger than that of the foundation slab, a grouting hole is formed in the centroid position of the bedrock, a fiber rib anti-floating anchor rod body and the foundation slab are jointly poured for simulating the anchoring of the anti-floating anchor rod and the foundation slab, and the fiber rib anti-floating anchor rod body is placed in the center of the grouting hole and is poured with M30 cement mortar for simulating the anchoring of the anti-floating anchor rod in the bedrock; the anchor rod body stress meter is embedded in the fiber bar anti-floating anchor rod body in a quasi-distribution mode, the anchor rod body stress meter is a multi-point fiber bragg grating string consisting of self-compensation type micro fiber bragg grating strain sensors, the self-compensation type micro fiber bragg grating strain sensors are arranged in a quasi-distribution mode, one is arranged at intervals of 5cm in a range of 30cm near a loading surface of a foundation slab and bedrock, and one is arranged at intervals of 10cm when the loading surface exceeds the range; the first constant stiffness plate, the second constant stiffness plate and the jack form a loading system, the central axis of the loading system is collinear with the axis of the fiber rib anti-floating anchor rod body, the first constant stiffness plate is installed on the loading surface of the foundation slab and the bedrock, the second constant stiffness plate is installed on the side surface of the first constant stiffness plate on the same side with the loading surface, the jack is arranged above the bearing platform, a load sensor is arranged between the second constant stiffness plate and the jack, the load sensor, the automatic displacement acquisition meter, the displacement base and the anchor rod rigid wing form a measuring system together, and the anchor rod rigid wing is arranged at a position 5cm away from the foundation slab and the top surface of the bedrock; the automatic displacement acquisition meter is horizontally arranged on the anchor rod rigid wing, the displacement base is arranged at the upper end of the loading surface, three centering rings are arranged at trisection positions in the length direction of the bedrock, and the centering rings are connected with the fiber rib anti-floating anchor rod body in a coupling mode.
The smooth base is made of a single-side smooth steel plate with the length of 5m, the width of 2m and the thickness of 2cm and is used for reducing the friction resistance of the bottom surface in a drawing test; the supporting platform is made of steel plates with the thickness of 3cm, the length of 1.2m and the width of 0.8m, and can reduce friction between the supporting base plate and bedrock and the ground and ensure the weight of the supporting base plate and the bedrock.
The bearing platform is made by placing a steel plate on a steel cushion block, wherein the thickness of the steel plate is 1cm, the length of the steel plate is 80cm, the width of the steel plate is 50cm, the thickness of the steel cushion block is 3cm, the length of the steel cushion block is 40cm, and the width of the steel cushion block is 40cm, and during a test, the steel cushion block is used for lifting 3-2 parts of the steel plate to a loading position required by the test to be used as a temporary supporting and positioning platform of a loading system.
The foundation slab is of a cast-in-place reinforced concrete cuboid structure, the strength grade of concrete is determined according to design requirements, the strength grade of the concrete is C30 in general conditions, the length of the foundation slab is 1m, the width of the foundation slab is 0.8m, and the height of the foundation slab is 0.8 m; the bedrock is a cast-in-place concrete to simulate a medium-stroke cemented hard rock, the strength of the bedrock is controlled according to the compressive strength of the concrete, and the bedrock is 1.5m long, 0.8cm wide and 0.8m high; the grouting holes are through holes reserved by PVC pipes (the diameter is 9cm, the length is 1m, vaseline is coated on the outer surfaces of the PVC pipes, and the PVC pipes are conveniently taken out after the concrete reaches the curing time) when concrete is poured; the fiber-reinforced anti-floating anchor rod body is a full-thread solid rod made of glass fiber reinforced composite (GFRP), so that the bond stress between the anchor rod body and an anchoring body can be enhanced, and sufficient anchoring friction force is provided; the self-compensating miniature fiber bragg grating strain sensor in the anchor rod body stress meter is small in size and convenient to implant, influences of temperature changes on test results can be eliminated, and the temperature sensor does not need to be arranged independently.
The first constant-rigidity plate is 15cm long, 15cm wide and 3cm thick; the second constant-rigidity plate is 20cm long, 15cm wide and 3cm thick; the jack adopts a 50-ton oil pressure punching jack for providing enough drawing force.
The load sensor is a vibrating wire type automatic acquisition pressure sensor, the automatic displacement acquisition meter is a dial indicator displacement meter, and the automatic displacement acquisition meter is connected with an external acquisition system to realize automatic acquisition of deformation in the loading process; the displacement base consists of a magnetic base, a lever, an expansion bolt, a nut and a supporting steel plate, wherein the magnetic base is arranged on the supporting steel plate, the lever is arranged in the middle of the magnetic base, and the supporting steel plate in the displacement base is respectively fixed on the foundation slab and the bedrock by the expansion bolt and the matched nut; the anchor rod rigid wing is formed by welding angle iron of 5cm multiplied by 0.5cm and a semicircular steel pipe with the outer diameter of 2cm and the wall thickness of 0.3cm, and is adhered to the body of the fiber rib anti-floating anchor rod by structural adhesive; the centering device is a plastic frame ring with the outer diameter of 8 cm.
Before the device is used, in order to ensure that the axis of the rod body of the fiber rib anti-floating anchor rod is pulled in a drawing test, the horizontal of the central axis of the foundation slab, the central axis of the bedrock, the central axis of the fiber rib anti-floating anchor rod and the central axis of the loading system are ensured as much as possible; the compactness and the strength of the mortar and the epoxy resin in the concrete and the grouting holes of the foundation slab and the bedrock are ensured.
Compared with the prior art, the method is simple, convenient and fast to install, strong in operability, safe, reliable, high in testing precision, low in cost and high in repeated utilization rate, and can truly and accurately reflect the working state of the anti-floating anchor rod in the actual engineering.
Description of the drawings:
fig. 1 is a schematic diagram of a main structure principle of an indoor simulation test device for stress characteristics of the fiber rib anti-floating anchor rod.
Fig. 2 is a top view of a main structure of the device for performing an indoor simulation test on the stress characteristic of the fiber rib anti-floating anchor rod.
Fig. 3 is a schematic structural diagram of the anchor rod rigid wing of the present invention, wherein (a) is a front view and (b) is a top view.
Fig. 4 is a schematic structural diagram of the centralizer of the present invention.
Fig. 5 is a schematic structural diagram of the displacement base according to the present invention, wherein (a) is a front view and (b) is a top view.
The specific implementation mode is as follows:
the invention is further illustrated by the following examples in conjunction with the accompanying drawings.
Example (b):
this embodiment carries out indoor simulation test device realization through anti-floating anchor rod atress characteristic of fibre muscle, and its concrete process is:
(1) manufacturing a bedrock 5: firstly, vertically building a template of bedrock 5, fixing a PVC pipe coated with a release agent on the outer side on the position of an axis in the template of the bedrock 5, pouring concrete by adopting the prior art, manufacturing a concrete standard test block under the same condition, taking out the PVC pipe to form a grouting hole 6 before final setting, inserting a fiber bar anti-floating anchor bar body 7 implanted with a bar body stress meter 8 into the grouting hole 6, installing a centering device 16 at the pre-marked position of the fiber bar anti-floating anchor bar body 7, pouring M30 cement mortar, manufacturing a mortar test block at the same time, curing to the age to form a mortar anchoring body, and detecting the strength of the mortar anchoring body; in the process, the stress meter 8 of the anchor rod body is well protected, and the survival rate of the anchor rod body is ensured to reach 95 percent;
(2) manufacturing a foundation slab 4: horizontally placing a bed rock 5 with the strength reaching 100% on a supporting platform 2 of a smooth base 1, sequentially penetrating a second constant-stiffness plate 10, a jack 11 and a load sensor 12 through a fiber rib anti-floating anchor rod body 7 and installing the second constant-stiffness plate, the jack 11, the load sensor 12 and the fiber rib anti-floating anchor rod body 7 on the upper surface of a bearing platform 3 to ensure that the centroids of the second constant-stiffness plate 10, the jack 11, the load sensor 12 and the fiber rib anti-floating anchor rod body 7 are in the same straight line, building a template of a foundation slab 5 on the supporting platform 2, binding a reinforcement cage, fixing the position of the fiber rib anti-floating anchor rod body 7 in the foundation rock 5 in the template of the foundation slab 4, pouring concrete, manufacturing a concrete standard test block and testing the strength under the same condition, curing to the age, determining the relative position of the foundation slab 4 and the relative position of the bed rock 5 again before final setting of the concrete standard test block, and ensuring;
(3) and mounting a displacement meter: firstly, drilling holes at the positions above the centers of a foundation slab 4 and a bedrock 5 by using an electric drill to install expansion bolts and steel plates of a displacement base 14, then adhering anchor rod rigid wings 15 at corresponding positions by using epoxy resin and curing agent mixed liquid with the mass ratio of 2:1, maintaining for 3 days, adsorbing a magnetic seat 14-1 on a supporting steel plate 14-5 after the epoxy resin is completely cured, installing an automatic displacement acquisition meter 13, and finally compressing a telescopic rod of the automatic displacement acquisition meter 13 for a certain distance (ensuring that the telescopic rod can extend for at least 4cm during a test and the anchor rod is damaged when the displacement exceeds 4 cm) to be aligned and placed on the anchor rod rigid wings 15, so as to ensure that the automatic displacement acquisition meter 13 is horizontal and vertical;
(4) and (3) carrying out a test: the jack 11 and an external hydraulic oil pump are firmly connected by a matched oil pipe, the automatic displacement acquisition meter 13 and the anchor rod body stress meter 8 are respectively connected with a demodulator interface of an external acquisition system, initial reading is recorded, the survival rate of the sensor to be tested meets the requirement and then is loaded step by step, test data is recorded, and the test loading, unloading and termination loading conditions and the judgment standard of anchor rod damage are executed according to the technical specification for supporting foundation pits of buildings (JGJ 120-2012).
The main structure of the device for performing indoor simulation test on the stress characteristic of the fiber rib anti-floating anchor rod in the embodiment comprises a smooth base 1, a supporting platform 2, a bearing platform 3, a foundation slab 4, bedrock 5, a grouting hole 6, a fiber rib anti-floating anchor rod body 7, an anchor rod body stress meter 8, a first constant stiffness plate 9, a second constant stiffness plate 10, a jack 11, a load sensor 12, an automatic displacement acquisition meter 13, a displacement base 14, an anchor rod rigid wing 15 and a centering device 16; the base system is formed by a smooth base 1 and supporting platforms 2 together, two supporting platforms 2 are symmetrically placed on the smooth base 1, five spherical hinge supports 17 are uniformly welded in the center of the lower surface of each supporting platform 2 along the horizontal direction, a bearing platform 3 is arranged between the two supporting platforms 2, a foundation slab 4 and a bedrock 5 are respectively installed on the two supporting platforms 2, the length of the bedrock 5 is larger than that of the foundation slab 4, a grouting hole 6 is formed in the centroid position of the bedrock 5, a fiber rib anti-floating anchor rod body 7 and the foundation slab 4 are poured together for simulating the anchoring of an anti-floating anchor rod and the foundation slab, and the fiber rib anti-floating anchor rod body 7 is placed in the center of the grouting hole 6 and is poured with M30 cement mortar for simulating the anchoring of the anti-floating anchor rod in the bedrock; the anchor rod body stress meter 8 is embedded in the fiber bar anti-floating anchor rod body 7 in a quasi-distribution mode, the anchor rod body stress meter 8 is a multi-point fiber bragg grating string consisting of self-compensation type micro fiber bragg grating strain sensors, the self-compensation type micro fiber bragg grating strain sensors are arranged in a quasi-distribution mode, one is arranged in a range of 30cm near the loading surface of the foundation slab 4 and the bedrock 5 every 5cm, and one is arranged in a range of 10cm beyond the range; the first constant stiffness plate 9, the second constant stiffness plate 10 and the jack 11 form a loading system, the central axis of the loading system is collinear with the axis of the fiber rib anti-floating anchor rod body 7, the first constant stiffness plate 9 is installed on the loading surface of the foundation slab 4 and the bedrock 5, the second constant stiffness plate 10 is installed on the side surface of the first constant stiffness plate 9 on the same side of the loading surface, the jack 11 is arranged above the bearing platform 3, a load sensor 12 is arranged between the second constant stiffness plate 10 and the jack 11, the load sensor 12, an automatic displacement acquisition meter 13, a displacement base 14 and an anchor rod rigid wing 15 form a measuring system together, and the anchor rod rigid wing 15 is arranged at a position 5cm away from the top surfaces of the foundation slab 4 and the bedrock 5; the automatic displacement acquisition meter 13 is horizontally arranged on the anchor rod rigid wing 15, the displacement base 14 is arranged at the upper end of the loading surface, three centering rings 16 are arranged at trisection positions in the length direction of the bedrock 5, and the centering rings 16 are coupled and connected with the fiber rib anti-floating anchor rod body 7.
The smooth base 1 of the embodiment is made of a single-sided smooth steel plate with the length of 5m, the width of 2m and the thickness of 2cm, and is used for reducing the friction resistance of the bottom surface during a drawing test; the supporting platform 2 is made of a steel plate with the thickness of 3cm, the length of 1.2m and the width of 0.8m, and the supporting platform 2 can reduce friction between the supporting base plate 4 and the bedrock 5 and the ground and ensure the weight of the supporting base plate 4 and the bedrock 5.
In the embodiment, the bearing platform 3 is formed by placing a steel plate 3-2 on a steel cushion block 3-1, the steel plate 3-2 is 1cm thick, 80cm long and 50cm wide, the steel cushion block 3-1 is 3cm thick, 40cm long and 40cm wide, and the steel cushion block 3-1 is used for raising the steel plate 3-2 to a loading position required by a test to be used as a temporary supporting and positioning platform of a loading system during the test.
In this embodiment, the foundation slab 4 is a rectangular structure of cast-in-place reinforced concrete, the strength grade of the concrete is determined according to the design requirement, the strength grade of the concrete is C30 in general cases, the length of the foundation slab 4 is 1m, the width is 0.8m, and the height is 0.8 m; the bedrock 5 is made of cast-in-place concrete to simulate the stroke hardened rock, the strength of the bedrock 5 is controlled according to the compressive strength of the concrete, and the length is 1.5m, the width is 0.8cm, and the height is 0.8 m; the grouting hole 6 is a through hole reserved by a PVC pipe (the diameter is 9cm, the length is 1m, vaseline is coated on the outer surface of the PVC pipe, and the PVC pipe is conveniently taken out after the concrete reaches the curing time) when concrete is poured; the fiber bar anti-floating anchor rod body 7 is a full-thread solid rod made of glass fiber reinforced composite (GFRP), so that the bond stress between the anchor rod body and an anchoring body can be enhanced, and sufficient anchoring friction force is provided; the self-compensating miniature fiber bragg grating strain sensor in the anchor rod body stress meter 8 is small in size and convenient to implant, influences of temperature changes on test results can be eliminated, and the temperature sensor does not need to be arranged independently.
In the embodiment, the length of the first constant-stiffness plate 9 is 15cm, the width of the first constant-stiffness plate is 15cm, and the thickness of the first constant-stiffness plate is 3 cm; the second constant stiffness plate 10 is 20cm long, 15cm wide and 3cm thick; the jack 11 uses a 50 ton hydraulic feed-through jack for providing sufficient pull-out force.
In this embodiment, the load sensor 12 is a vibrating wire type automatic acquisition pressure sensor, the automatic displacement acquisition meter 13 is a dial gauge displacement meter, and the automatic displacement acquisition meter 13 is connected with an external acquisition system to realize automatic acquisition of deformation in a loading process; the displacement base 14 consists of a magnetic base 14-1, a lever 14-2, an expansion bolt 14-3, a nut 14-4 and a supporting steel plate 14-5, wherein the magnetic base 14-1 is arranged on the supporting steel plate 14-5, the lever 14-2 is arranged in the middle of the magnetic base 14-1, and the supporting steel plate 14-5 in the displacement base 14 is respectively fixed on the foundation slab 4 and the bedrock 5 by the expansion bolt 14-3 and the matched nut 14-4; the anchor rod rigid wing 15 is formed by welding angle iron of 5cm multiplied by 0.5cm and a semicircular steel pipe with the outer diameter of 2cm and the wall thickness of 0.3cm, and is adhered to the fiber rib anti-floating anchor rod body 7 by structural adhesive; the centralizer 16 is a plastic cage ring with an outer diameter of 8 cm.
Claims (7)
1. The indoor simulation test method for the stress characteristic of the fiber rib anti-floating anchor rod is characterized by being realized in an indoor simulation test device for the stress characteristic of the fiber rib anti-floating anchor rod, and the concrete process is as follows:
(1) preparing a bedrock: firstly, vertically building a template of bedrock, fixing a PVC pipe coated with a release agent on the outer side on the position of a central axis in the template of the bedrock, pouring concrete by adopting the prior art, manufacturing a concrete standard test block under the same condition, taking out the PVC pipe to form a grouting hole before final setting, inserting a fiber bar anti-floating anchor rod body planted with an anchor rod body stressometer into the grouting hole, installing a centering device at the pre-marked position of the fiber bar anti-floating anchor rod body, pouring M30 cement mortar, manufacturing a mortar test block at the same time, curing to the age to form a mortar anchoring body, and detecting the strength of the mortar anchoring body; in the process, the stress meter of the anchor rod body is well protected, and the survival rate of the anchor rod body is ensured to reach 95 percent;
(2) manufacturing a foundation slab: horizontally placing a bed rock with the strength reaching 100% on a supporting platform of a smooth base, sequentially penetrating a second constant-stiffness plate, a jack and a load sensor through a fiber rib anti-floating anchor rod body and installing the second constant-stiffness plate, the jack and the load sensor on the upper surface of a bearing platform, ensuring that the centroids of the second constant-stiffness plate, the jack, the load sensor and the fiber rib anti-floating anchor rod body are in the same straight line, building a template of a foundation slab on the supporting platform, binding a reinforcement cage, fixing the position of the fiber rib anti-floating anchor rod body in the bed rock in the template of the foundation slab, finally pouring concrete to manufacture the foundation slab, manufacturing a concrete standard test block under the same condition, testing the strength of the concrete standard test block, curing the concrete standard test block to the age, determining the relative positions of the foundation slab and the bed rock again before final setting of the concrete standard test block, and ensuring the level;
(3) mounting a displacement meter: firstly, drilling holes at the positions above the centers of a foundation slab and bedrock by using an electric drill, mounting expansion bolts and steel plates of a displacement base, then sticking anchor rod rigid wings at corresponding positions by using epoxy resin and curing agent mixed liquid with the mass ratio of 2:1, maintaining for 3 days, adsorbing a magnetic base on a supporting steel plate after the epoxy resin is completely cured, mounting an automatic displacement acquisition meter, and finally compressing and aligning a telescopic rod of the automatic displacement acquisition meter on the anchor rod rigid wings to ensure that the automatic displacement acquisition meter is horizontal and vertical;
(4) the test was carried out: the jack and the external hydraulic oil pump are firmly connected by a matched oil pipe, the automatic displacement acquisition meter and the anchor rod body stress meter are respectively connected with a demodulator interface of an external acquisition system, initial reading is recorded, the survival rate of the sensor meets the requirement and then is loaded step by step, test data is recorded, and the test loading, unloading and termination loading conditions and the anchor rod damage judgment standard are executed according to the technical specification for supporting the foundation pit of the building (JGJ 120-2012).
2. The method for indoor simulation test of stress characteristics of the fiber-reinforced anti-floating anchor rod according to claim 1, wherein the main structure of the device for indoor simulation test of stress characteristics of the fiber-reinforced anti-floating anchor rod comprises a smooth base, a supporting platform, a bearing platform, a foundation slab, bedrock, a grouting hole, a fiber-reinforced anti-floating anchor rod body, an anchor rod body stress meter, a first constant stiffness plate, a second constant stiffness plate, a jack, a load sensor, an automatic displacement acquisition meter, a displacement base, an anchor rod rigid wing and a centering device; the base system is composed of a smooth base and supporting platforms, two supporting platforms are symmetrically arranged on the smooth base, five spherical hinge supports are uniformly welded in the center of the lower surface of each supporting platform along the horizontal direction, a bearing platform is arranged between the two supporting platforms, a foundation slab and a bedrock are respectively arranged on the two supporting platforms, the length of the bedrock is larger than that of the foundation slab, a grouting hole is formed in the centroid position of the bedrock, a fiber rib anti-floating anchor rod body and the foundation slab are jointly poured for simulating the anchoring of the anti-floating anchor rod and the foundation slab, and the fiber rib anti-floating anchor rod body is placed in the center of the grouting hole and is poured with M30 cement mortar for simulating the anchoring of the anti-floating anchor rod in the bedrock; the anchor rod body stress meter is embedded in the fiber bar anti-floating anchor rod body in a quasi-distribution mode, the anchor rod body stress meter is a multi-point fiber bragg grating string consisting of self-compensation type micro fiber bragg grating strain sensors, the self-compensation type micro fiber bragg grating strain sensors are arranged in a quasi-distribution mode, one is arranged at intervals of 5cm in a range of 30cm near a loading surface of a foundation slab and bedrock, and one is arranged at intervals of 10cm when the loading surface exceeds the range; the first constant stiffness plate, the second constant stiffness plate and the jack form a loading system, the central axis of the loading system is collinear with the axis of the fiber rib anti-floating anchor rod body, the first constant stiffness plate is installed on the loading surface of the foundation slab and the bedrock, the second constant stiffness plate is installed on the side surface of the first constant stiffness plate on the same side with the loading surface, the jack is arranged above the bearing platform, a load sensor is arranged between the second constant stiffness plate and the jack, the load sensor, the automatic displacement acquisition meter, the displacement base and the anchor rod rigid wing form a measuring system together, and the anchor rod rigid wing is arranged at a position 5cm away from the foundation slab and the top surface of the bedrock; the automatic displacement acquisition meter is horizontally arranged on the anchor rod rigid wing, the displacement base is arranged at the upper end of the loading surface, three centering rings are arranged at trisection positions in the length direction of the bedrock, and the centering rings are connected with the fiber rib anti-floating anchor rod body in a coupling mode.
3. The indoor simulation test method for the stress characteristic of the fiber-reinforced anti-floating anchor rod according to claim 2, wherein the smooth base is made of a single-sided smooth steel plate with the length of 5m, the width of 2m and the thickness of 2cm and is used for reducing the friction resistance of the bottom surface during a drawing test; the supporting platform is made of steel plates with the thickness of 3cm, the length of 1.2m and the width of 0.8m, and can reduce friction between the supporting base plate and bedrock and the ground and ensure the weight of the supporting base plate and the bedrock.
4. The indoor simulation test method for the stress characteristics of the fiber-reinforced anti-floating anchor rod according to claim 2, wherein the bearing platform is made of a steel plate which is placed on a steel cushion block, the steel plate is 1cm thick, 80cm long and 50cm wide, the steel cushion block is 3cm thick, 40cm long and 40cm wide, and the steel cushion block is used for raising the steel plate to a loading position required by the test to serve as a temporary supporting and positioning platform of a loading system during the test.
5. The indoor simulation test method for the stress characteristic of the fiber-reinforced anti-floating anchor rod according to claim 2, wherein the foundation slab is a cast-in-place reinforced concrete rectangular structure, the strength grade of concrete is C30, the length of the foundation slab is 1m, the width of the foundation slab is 0.8m, and the height of the foundation slab is 0.8 m; the bedrock is a cast-in-place concrete to simulate a medium-stroke cemented hard rock, the strength of the bedrock is controlled according to the compressive strength of the concrete, and the bedrock is 1.5m long, 0.8cm wide and 0.8m high; the grouting hole is a through hole reserved by a PVC pipe when concrete is poured; the fiber-reinforced anti-floating anchor rod body is a full-thread solid rod made of glass fiber reinforced composite materials, so that the gripping force between the anchor rod body and an anchoring body can be enhanced, and sufficient anchoring friction force is provided; the self-compensating miniature fiber bragg grating strain sensor in the anchor rod body stress meter is small in size and convenient to implant, influences of temperature changes on test results can be eliminated, and the temperature sensor does not need to be arranged independently.
6. The indoor simulation test method for the stress characteristics of the fiber-reinforced anti-floating anchor rod according to claim 2, wherein the first constant-stiffness plate is 15cm long, 15cm wide and 3cm thick; the second constant-rigidity plate is 20cm long, 15cm wide and 3cm thick; the jack adopts a 50-ton oil pressure punching jack for providing enough drawing force.
7. The indoor simulation test method for the stress characteristics of the fiber-reinforced anti-floating anchor rod according to claim 2, wherein the load sensor is a vibrating wire type automatic acquisition pressure sensor, the automatic displacement acquisition meter is a dial gauge displacement meter, and the automatic displacement acquisition meter is connected with an external acquisition system to realize automatic acquisition of deformation in a loading process; the displacement base consists of a magnetic base, a lever, an expansion bolt, a nut and a supporting steel plate, wherein the magnetic base is arranged on the supporting steel plate, the lever is arranged in the middle of the magnetic base, and the supporting steel plate in the displacement base is respectively fixed on the foundation slab and the bedrock by the expansion bolt and the matched nut; the anchor rod rigid wing is formed by welding angle iron of 5cm multiplied by 0.5cm and a semicircular steel pipe with the outer diameter of 2cm and the wall thickness of 0.3cm, and is adhered to the body of the fiber rib anti-floating anchor rod by structural adhesive; the centering device is a plastic frame ring with the outer diameter of 8 cm.
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