CN113281190A - Hydraulic engineering asphalt concrete direct tensile test device and application method thereof - Google Patents
Hydraulic engineering asphalt concrete direct tensile test device and application method thereof Download PDFInfo
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- CN113281190A CN113281190A CN202110400382.7A CN202110400382A CN113281190A CN 113281190 A CN113281190 A CN 113281190A CN 202110400382 A CN202110400382 A CN 202110400382A CN 113281190 A CN113281190 A CN 113281190A
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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
- G01N3/18—Performing tests at high or low temperatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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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
- G01N2203/0014—Type of force applied
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- G01N2203/0017—Tensile
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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
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Abstract
The invention discloses a hydraulic engineering asphalt concrete direct tensile test device which comprises a test piece connecting system, a sensor system, an acquisition system, a loading system and a temperature control system, wherein the sensor system is connected with the test piece connecting system; the test piece connecting system comprises a sliding T-shaped connecting piece, a floating spherical hinge, a stretching clamp, a test piece, a Y-shaped joint and an I-shaped joint, the floating spherical hinge is connected with the T-shaped connecting piece, the stretching clamp and the Y-shaped joint and the I-shaped joint, and the test piece is bonded with the stretching clamp; the sensor comprises a force sensor and a grating displacement sensor, and the force sensor is respectively connected with the T-shaped connecting piece and the floating spherical hinge; the loading system is an MTS (maximum Transmission System) static power actuator fixed on a loading table board and can provide static and sine and other dynamic loading modes, the temperature control system is a high-low temperature environment box, and the application method of the device is further provided, so that the problems that the installation and loading processes are difficult to align, the size of a test piece is small, the connection between the test piece and a clamp is not firm, the installation process is complicated, and the test precision is low in a hydraulic asphalt concrete tensile test are solved.
Description
Technical Field
The invention belongs to the technical field of civil engineering experiments, and relates to a direct tensile test device for hydraulic asphalt concrete.
The invention also relates to an application method of the hydraulic engineering asphalt concrete direct tensile test device.
Background
The hydraulic asphalt concrete is a composite material formed by mixing coarse aggregate, fine aggregate, asphalt, filler and other materials according to a certain proportion, has the advantages of good deformability, strong seepage-proofing performance and the like, and is mainly applied to hydraulic seepage-proofing body structures, such as seepage-proofing core walls or panels of earth and rockfill dams. A large number of researches show that when the dam foundation of the earth-rock dam is unevenly settled, the asphalt concrete face plate is inevitably under the action of tensile stress; when the earth-rock dam is subjected to slip deformation towards the center of a river valley along a steep bank slope, the asphalt concrete core wall shoulder is inevitably subjected to tensile stress, and the tensile stress is increased along with the increase of the height of the core wall dam. In actual engineering, the tensile strength and tensile deformation of asphalt concrete are far lower than the compressive strength and compressive deformation, so the size and damage degree of a structural damage area of the seepage-proofing body depend on the tensile mechanical characteristics of asphalt concrete materials to a great extent, and when the asphalt concrete is subjected to structural tensile fracture damage, the structural tensile fracture damage inevitably causes great harm to the safety of a dam.
The common methods for testing the tensile mechanical property indexes of the asphalt concrete material comprise a direct tensile test, a splitting test and a bending test, and the axial direct tensile test is the most suitable and accurate test method for obtaining the tensile mechanical property of the material. However, there are several problems in currently conducting axial direct tensile tests on bituminous concrete materials: firstly, the test piece is difficult to guarantee the axle center tensile state in the installation and loading process, and the tensile mechanics index that leads to the test has great error. Secondly, the proper size of the tensile test piece is selected according to the raw material and the forming characteristics of the hydraulic asphalt concrete. The existing test piece for carrying out the direct tensile test of the hydraulic asphalt concrete is a prism with the size of 40mm multiplied by 220mm, and for the small-size prism test piece, if the test piece is directly molded and prepared, the compactness cannot be ensured, and the requirement of the anti-seepage performance of the hydraulic asphalt concrete cannot be met, so under the normal condition, the prism test piece is formed by firstly performing laboratory molding (Marshall compaction molding, static pressure molding and the like) or on-site core drilling and sampling, then performing cutting, and performing cutting again can inevitably cause initial damage to the test piece. In addition, the maximum aggregate size of the hydraulic asphalt concrete is 19mm, and the influence of the aggregate size effect needs to be considered when a tensile test is carried out by adopting a test piece with the cross-sectional size of 40mm multiplied by 40 mm. Thirdly, the accuracy of the test result is influenced by the connection mode of the test piece and the clamp. As an inhomogeneous phase change material, the temperature or the loading rate has obvious influence on the mechanical properties of tensile strength, rigidity and the like of the asphalt concrete, and the rigidity of the asphalt concrete is increased along with the reduction of the temperature or the improvement of the loading rate, so that the connection rigidity of a test piece and a clamp is required to be higher. In addition, when a tensile test is carried out using a test piece having a larger cross-sectional size, higher requirements are placed on the connection rigidity and stability of the test piece and the jig. And fourthly, when the material is cracked, the crack is rapidly expanded, the stress is rapidly reduced, and the acquisition precision of the conventional sensor is difficult to accurately measure the stress-strain curve of the test piece after the test piece reaches the peak stress.
Therefore, aiming at the characteristics of the hydraulic asphalt concrete material, the research on the hydraulic asphalt concrete axial tensile test device and the application method thereof has very important theoretical significance and engineering application value.
Disclosure of Invention
The invention aims to provide a hydraulic engineering asphalt concrete direct tensile test device, which solves the problems that the existing hydraulic engineering asphalt concrete tensile test is difficult to center in the installation and loading processes, the size of a test piece is small, the connection between the test piece and a clamp is not firm, the installation process is complicated, and the test precision is low.
The invention also aims to provide an application method of the hydraulic engineering asphalt concrete direct tensile test device.
The hydraulic engineering asphalt concrete direct tensile test device comprises a support frame body, wherein a horizontal cross beam is arranged at the top of the support frame body, a loading table top parallel to the cross beam is arranged at the bottom of the support frame body, an MTS actuator is connected to the bottom of the cross beam, a first sliding T-shaped connecting piece is connected to the bottom of the MTS actuator, and the first sliding T-shaped connecting piece is connected with a first tensile clamp through a first floating spherical hinge; a tension sensor is also arranged between the first sliding T-shaped connecting piece and the first floating spherical hinge;
the top of the loading table top is connected with a loading platform base, one end of the loading platform base, which is far away from the loading table top, is connected with a second sliding T-line connecting piece, the second sliding T-line connecting piece is connected with a second stretching clamp through a second floating spherical hinge, the first stretching clamp and the second stretching clamp are opposite, and all the parts are positioned on the central axis of the beam and the loading table top; the device comprises a first tensile clamp, a second tensile clamp, a grating displacement sensor and a high and low temperature environment box, and is characterized by further comprising a test piece, wherein the test piece is clamped between the first tensile clamp and the second tensile clamp, the grating displacement sensor is further arranged on the test piece, and the test piece is located in the high and low temperature environment box.
The first technical solution of the present invention is also characterized in that:
the supporting frame body also comprises two steel columns which are arranged in parallel, the two steel columns are positioned between the cross beam and the loading table top, and the steel columns are perpendicular to the cross beam;
the first sliding T-shaped connecting piece comprises a first sliding groove and a first clamping groove, the first sliding groove is fixedly connected with the MTS actuator, the first sliding T-shaped connecting piece further comprises a first T-shaped connecting piece, the horizontal end of the first T-shaped connecting piece is embedded into the first clamping groove, a plurality of steel rollers are further arranged on the inner side of the first clamping groove, and the first T-shaped connecting piece is movably connected with the first clamping groove through the steel rollers; the end part of the vertical end of the first T-shaped connecting piece is provided with a screw hole, a screw rod is embedded in the screw hole, the first T-shaped connecting piece is fixedly connected with the first floating spherical hinge through the screw rod, and the tension sensor is positioned at the vertical end of the first T-shaped connecting piece;
fastening bolts are arranged on two sides of the outer portion of the first clamping groove respectively and extend into the first clamping groove to be connected with the first T-shaped connecting piece;
the structure of the second sliding T-shaped connecting piece is the same as that of the first sliding T-shaped connecting piece, a sliding chute of the second sliding T-shaped connecting piece extends into the loading platform base to be fixedly connected with the loading platform base, and a T-shaped connecting piece of the second sliding T-shaped connecting piece is connected with a second floating spherical hinge;
the first stretching clamp comprises a C-shaped clamp and side plates positioned on two sides of the C-shaped clamp, the side plates are connected with the C-shaped clamp through bolts, the bottom of the C-shaped clamp is further provided with screw holes, screw rods are embedded in the screw holes, and one end, far away from the first sliding T-shaped connecting piece, of the first floating spherical hinge is fixedly connected with the first stretching clamp through the screw rods;
the second stretching clamp is the same as the first stretching clamp in structure, the bottom of the second stretching clamp is connected with a Y-shaped joint through a screw hole, an I-shaped joint is embedded in the opening end of the Y-shaped joint, the second stretching clamp further comprises a cylindrical pin, the cylindrical pin sequentially penetrates through the Y-shaped joint and the I-shaped joint to fix the Y-shaped joint and the I-shaped joint, and one end, far away from the Y-shaped joint, of the I-shaped joint is connected with one end, far away from the second sliding T-shaped connecting piece, of a second floating spherical hinge;
the test piece is a dumbbell-shaped test piece, the height and width dimension B of a test area of the test piece is 3-5 times of the maximum aggregate, the length-width ratio L/B of the test area is 1.2-1.5, the ratio of the total length L of the test piece to the width B of the middle part of the test area is 3.5-4.5, the ratio of the total length L to the width B of the end part of the test piece is 2.5-3, and the side slope n is 2.5-4; the test piece is positioned between the first tensile clamp and the second tensile clamp, one end of the test piece is embedded into the C-shaped clamp of the clamp, the test piece is fixedly connected with the C-shaped clamp through a strong adhesive layer, and a rubber pad is arranged between the side plate and the test piece;
wherein crowning low temperature environment bottom of the case both ends still are connected with the crane respectively, the crane is fixed in and is located loading platform base both sides on the loading mesa, and crowning low temperature environment bottom of the case both sides still are connected with the wheel, and crane and crowning low temperature environment case junction tip are provided with the guide rail, the guide rail is embedded to have the draw-in groove, and the wheel is located the guide rail and cooperates with the guide rail.
The second technical scheme of the invention is that the application method of the hydraulic engineering asphalt concrete direct tensile test device is implemented by adopting the hydraulic engineering asphalt concrete direct tensile test device according to the following steps:
the specific process of on-site forming is as follows: the method comprises the steps of preparing by on-site core drilling sampling, firstly drilling a sample with the length of not less than 320mm by using a drill bit with the inner diameter of not less than 150mm, and then cutting the sample according to the shape of the sample; the length, width and height size deviations of the test piece obtained by the method are +/-2 mm, +/-1 mm and +/-1 mm respectively;
the specific process of laboratory forming is as follows: at first, make up forming die, forming die includes two shaping curb plates, two end plates and bottom plate, all passes through bolted connection between the plywood piece, shaping curb plate center department be provided with test piece complex arch, the shaping technology is the two-sided real shaping of hitting of individual layer, concrete step is: firstly mixing an asphalt mixture, heating a forming die to 100-110 ℃ when the temperature range of the asphalt mixture is 145-155 ℃, coating a release agent, feeding the prepared asphalt mixture into the forming die, placing a flat plate on the upper part after the asphalt mixture is flattened, adjusting the flatness of the asphalt mixture by observing a leveling bead, pulling a compaction hammer to a preset height to freely fall down, uniformly compacting a test piece, then installing a bottom plate in the forming die on the upper part, overturning the test piece, compacting the test piece for the second time by adopting the same steps, and compacting the test piece for times until the density of the test piece reaches +/-1% of the density of a Marshall standard compacted test piece, wherein the height size deviation is +/-1 mm;
step 2, polishing the test piece, removing the mold after the test piece is naturally cooled, polishing the connection area of the end part of the test piece, polishing the upper end surface and the lower end surface of the test piece to be flat, and polishing the side surface and the inclined surface into a honeycomb pitted surface;
step 3, connecting the test piece with a clamp; connecting two ends of a test piece with a first tensile fixture and a second tensile fixture respectively through a strong adhesive and a rubber pad, then dividing a test area, wherein the length of the test area is not less than 100mm, measuring and recording the section size at two ends and the middle part of the test area by using vernier calipers, and installing grating displacement sensors in the test area, wherein the grating displacement sensors are symmetrically distributed and arranged in a flush manner around the test piece;
step 4, mounting a test piece; vertically arranging a first sliding T-shaped connecting piece and a second sliding T-shaped connecting piece, respectively connecting and fixing the sliding chutes of the two connecting pieces with an MTS actuator and a loading table top, adjusting the position of the T-shaped connecting piece through a steel roller, ensuring the central lines of the upper T-shaped connecting piece and the lower T-shaped connecting piece to be overlapped through an infrared vertical instrument, and then screwing and fixing the clamping groove to fix the T-shaped connecting piece; connecting a tension sensor, a first floating spherical hinge, a first tensile fixture and a test piece with a first sliding T-shaped connecting piece in sequence, connecting a second floating spherical hinge with a second sliding T-shaped connecting piece to enable the test piece to be in a free plumb state, connecting a Y-shaped joint and an I-shaped joint with the second tensile fixture and the second floating spherical hinge respectively, and inserting a cylindrical pin to complete the connection and installation of the test piece and loading equipment; adjusting the initial stretching state by adjusting the screw spacing between the second floating spherical hinge and the Y-shaped joint and the I-shaped joint;
The invention has the beneficial effects that:
according to the direct tensile test device for the hydraulic asphalt concrete and the application method thereof, the eccentric problem generated in the installation and tensile process of the asphalt concrete is reduced to the greatest extent by the sliding T-shaped connecting piece and the floating ball hinge; the Y-shaped joint and the I-shaped joint of the test piece connecting system can realize quick installation; the shape of the test piece and the connection mode of the test piece and the tensile clamp break through the problem that the asphalt concrete tensile test is limited by the size of the test piece, and the tensile fracture surface can be approximately generated on the middle section of the test piece; the test piece connecting system is provided with the high-precision and high-sensitivity tension sensor and the displacement sensor, so that not only can the mechanical data of the test piece before the tensile strength is reached be accurately acquired, but also indexes such as load, deformation and the like of the test piece after the tensile strength is reached can be accurately tested; in a word, the direct tensile test device for the hydraulic asphalt concrete and the application method thereof can not only carry out the direct tensile test of the hydraulic asphalt concrete in a unidirectional loading state, but also test the tensile mechanical properties of the hydraulic asphalt concrete under the reciprocating loading conditions of pull-pull circulation, loading and unloading and the like; the method is not only suitable for developing static and dynamic tensile mechanical tests of the asphalt concrete under the normal temperature condition, but also can test the tensile mechanical property under the low temperature condition.
Drawings
FIG. 1 is a schematic diagram of a direct tensile test device for a hydraulic asphalt concrete specimen according to the present invention;
FIG. 2a is a schematic diagram of the test piece size in the direct tensile test device for a hydraulic asphalt concrete test piece according to the present invention;
FIG. 2b is a schematic diagram showing the dimension of one end of a hydraulic engineering asphalt concrete specimen direct tensile test device;
FIG. 2c is a schematic diagram of the size of the other end of the test piece in the hydraulic engineering asphalt concrete test piece direct tensile test device;
FIG. 3a is a schematic side view of a sliding T-shaped member in a direct tensile testing apparatus for a hydraulic asphalt concrete specimen according to the present invention;
FIG. 3b is a schematic structural diagram of the front side of a sliding T-shaped member in the direct tensile test device for a hydraulic asphalt concrete specimen according to the present invention;
FIG. 4 is a schematic view of a tensile fixture in the direct tensile test device for a hydraulic asphalt concrete specimen according to the present invention;
FIG. 5a is a front view of the connection between a test piece and a tensile clamp in the direct tensile test device for a hydraulic asphalt concrete test piece of the invention;
FIG. 5b is a side view of the connection between the test piece and the tensile fixture in the direct tensile test device for the hydraulic asphalt concrete test piece of the present invention;
FIG. 6 is a schematic view of a Y-shaped joint in a direct tensile test device for a hydraulic asphalt concrete specimen according to the present invention;
FIG. 7 is a schematic view of an I-shaped joint in a direct tensile testing device for a hydraulic asphalt concrete specimen according to the present invention;
fig. 8 is a schematic view of a forming die in a hydraulic asphalt concrete specimen direct tensile test device of the invention.
In the figure, 1, a first sliding T-shaped connecting piece, 2, a second sliding T-shaped connecting piece, 3, a first stretching clamp, 4, a first floating spherical hinge, 5, a second floating spherical hinge, 6, a test piece, 7, a tension sensor, 8, a grating displacement sensor, 9, a cylindrical pin, 10, a high-temperature and low-temperature environment box, 11, an MTS actuator, 12, a loading platform base, 13, a loading table top, 14, a steel column, 15, a cross beam, 16, a first sliding chute, 17, a first clamping groove, 18, a steel roller, 19, a screw hole, 20, a first T-shaped connecting piece, 21, a side plate, 22, a C-shaped clamp, 23, a fastening bolt, 24, a strong adhesive layer, 25, a rubber pad, 26, a Y-shaped joint, 27, an I-shaped joint, 28, a guide rail, 29, a wheel, 30, a lifting frame, 31, an end plate, 32, a molded side plate, 33, a bottom plate, 34, a second stretching clamp and 35.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention provides a hydraulic engineering asphalt concrete direct tensile test device, which comprises a supporting frame body, wherein a horizontal cross beam 15 is arranged at the top of the supporting frame body, a loading table top 13 parallel to the cross beam 15 is arranged at the bottom of the supporting frame body, the supporting frame body also comprises two steel columns 14 arranged in parallel, the two steel columns 14 are positioned between the cross beam 15 and the loading table top 13, and the steel columns 14 are vertical to the cross beam 15; the bottom of the cross beam 15 is connected with an MTS actuator 11, the bottom of the MTS actuator 11 is connected with a first sliding T-shaped connecting piece 1, and the first sliding T-shaped connecting piece 1 is connected with a first stretching clamp 3 through a first floating spherical hinge 4; a tension sensor 7 is also arranged between the first sliding T-shaped connecting piece 1 and the first floating spherical hinge 4; the measurement ranges of the tension sensor 7 are 0-10 kN and 0-40 kN respectively, and the measurement precision is 0.05N-0.1N;
the top of the loading table top 13 is connected with a loading platform base 12, one end of the loading platform base 12, which is far away from the loading table top 13, is connected with a second sliding T-row connecting piece 2, the second sliding T-row connecting piece 2 is connected with a second stretching clamp 34 through a second floating spherical hinge 5, the first stretching clamp 3 is opposite to the second stretching clamp 34, and all the parts are positioned on the central axis of the beam 15 and the loading table top 13; the device also comprises a test piece 6, wherein the test piece 6 is clamped between the first stretching clamp 3 and the second stretching clamp 34, the test piece 6 is also provided with a grating displacement sensor 8, the measurement range of the grating displacement sensor 8 is 0-5 mm, the measurement precision is 0.001-0.005 mm, the working temperature range is-40-50 ℃, and the acquisition frequency of the data acquisition system is not less than 10000; the device also comprises a high-low temperature environment box 10, wherein the temperature variation range is-50 ℃, the control precision is 0.1-0.5 ℃, the clearance height size is 700-900 mm, and the clearance length and width size is 400-500 mm; the test piece 6 is positioned in the high-low temperature environment box 10; the two ends of the bottom of the high and low temperature environment box 10 are respectively connected with a lifting frame 30, the lifting frames 30 are fixed on the loading table top 13 and are positioned on two sides of the loading platform base 12, the two sides of the bottom of the high and low temperature environment box 10 are also connected with wheels 29, the end part of the joint of the lifting frame 30 and the high and low temperature environment box 10 is provided with a guide rail 28, a clamping groove is embedded in the guide rail 28, and the wheels 29 are positioned in the guide rail 28 and are matched with the guide rail; the high-low temperature environment box 10 can move on the loading table top 13 through a guide rail 28, move up and down through a lifting frame 30 and is fixed in a test area through a clamping groove;
the first floating spherical hinge 4 and the second floating spherical hinge 5 freely rotate within the range of-10 degrees to 10 degrees;
as shown in fig. 3a and 3b, the first sliding T-shaped connecting member 1 includes a first sliding groove 16 and a first clamping groove 17, the first sliding groove 16 is fixedly connected with the MTS actuator 11, and further includes a first T-shaped connecting member 20, a horizontal end of the first T-shaped connecting member 20 is embedded into the first clamping groove 17, a plurality of steel rollers 18 are further disposed inside the first clamping groove 17, and the first T-shaped connecting member 20 is movably connected with the first clamping groove 17 through the steel rollers 18; a screw hole 19 is formed in the end part of the vertical end of the first T-shaped connecting piece 20, a screw rod is embedded in the screw hole 19, the first T-shaped connecting piece 20 is fixedly connected with the first floating spherical hinge 4 through the screw rod, the tension sensor 7 is positioned at the vertical end of the first T-shaped connecting piece 20, fastening bolts 23 are respectively arranged on two sides of the outer part of the first clamping groove 17 and extend into the first clamping groove 17 to be connected with the first T-shaped connecting piece 20;
the second sliding T-row connecting piece 2 has the same structure as the first sliding T-row connecting piece 2, a sliding chute of the second sliding T-row connecting piece 2 extends into the loading platform base 12 to be fixedly connected with the loading platform base 12, and a T-shaped connecting piece of the second sliding T-row connecting piece 2 is connected with the second floating spherical hinge 5;
as shown in fig. 4, the first stretching clamp 3 includes a C-shaped clamp 22 and side plates 21 located at two sides of the C-shaped clamp 22, the side plates 21 are connected with the C-shaped clamp 22 through bolts 35, a screw hole is further formed in the bottom of the C-shaped clamp 22, a screw rod is embedded in the screw hole, and one end of the first floating spherical hinge (4) far away from the first sliding T-shaped connector 2 is fixedly connected with the first stretching clamp 3 through the screw rod;
as shown in fig. 6 and 7, the second stretching clamp 34 has the same structure as the first stretching clamp 3, the bottom of the second stretching clamp 34 is connected with a Y-shaped joint 26 through a screw hole, an I-shaped joint 27 is embedded in an open end of the Y-shaped joint 26, the second stretching clamp further comprises a cylindrical pin 9, the cylindrical pin 9 sequentially penetrates through the Y-shaped joint 26 and the I-shaped joint 27 to fix the Y-shaped joint 26 and the I-shaped joint 27, and one end of the I-shaped joint 27 far from the Y-shaped joint 26 is connected with one end of the second floating ball hinge 5 far from the second sliding T-row connector 2; the screw shaft diameters of the Y-shaped joint 26 and the I-shaped joint 27 are not less than 20 mm;
as shown in fig. 2a, 2B, 2c, 5a and 5B, the specimen 6 is a dumbbell-shaped specimen, the height and width dimension B of the test area of the specimen is 3-5 times of the maximum aggregate, the length-width ratio L/B of the test area is 1.2-1.5, the ratio of the total length L of the specimen to the middle width B of the test area is 3.5-4.5, the ratio of the total length L to the end width B of the specimen is 2.5-3, and the side slope n is 2.5-4; the test piece 6 is positioned between the first tensile clamp 3 and the second tensile clamp 34, one end of the test piece 6 is embedded into the C-shaped clamp 22 of the clamps, the test piece 6 is fixedly connected with the C-shaped clamp 22 through a strong adhesive layer 24, and a rubber pad 25 with the thickness of 1-2 mm is further arranged between the side plate 21 and the test piece 6;
the invention also provides an application method of the hydraulic engineering asphalt concrete direct tensile test device, and the hydraulic engineering asphalt concrete direct tensile test device is implemented according to the following steps:
the specific process of on-site forming is as follows: the method comprises the steps of preparing by on-site core drilling sampling, firstly drilling a sample with the length of not less than 320mm by using a drill bit with the inner diameter of not less than 150mm, and then cutting the sample according to the shape of a test piece 6; the length, width and height size deviations of the test piece obtained by the method are +/-2 mm, +/-1 mm and +/-1 mm respectively;
if the molding is carried out in a laboratory, a molding die matched with the molding method needs to be processed, and the specific process of the molding in the laboratory is as follows: as shown in fig. 8, at first, make up forming die, forming die includes two shaping curb plates 32, two end plates 31 and bottom plate 33, all passes through bolted connection between the plywood piece, and shaping curb plate 32 center department is provided with the arch with test piece 6 complex, and the forming process is the two-sided real shaping of hitting of individual layer, and concrete step is: preparing an asphalt mixture according to the mixing ratio required by the 'hydraulic asphalt concrete standard', wherein the temperature range of the asphalt mixture is 145-155 ℃, heating a forming die to 100-110 ℃, coating a release agent, feeding the prepared asphalt mixture into the forming die, placing a flat plate on the upper part after the asphalt mixture is flattened, adjusting the flatness of the asphalt mixture by observing a leveling bead, pulling a compaction hammer to a preset height to freely fall down, uniformly compacting a test piece, mounting a bottom plate 33 in the forming die on the upper part, overturning the test piece, carrying out secondary compaction on the test piece by adopting the same steps, the compaction times are based on that the density of the test piece reaches +/-1% of the density of a Marshall standard compaction test piece, and the height size deviation is +/-1 mm;
step 2, polishing the test piece 6, removing the mold after the test piece 6 is naturally cooled, polishing the connecting area of the end part of the test piece 6, polishing the upper end surface and the lower end surface of the test piece to be flat, and polishing the side surface and the inclined surface to be a honeycomb pitted surface;
step 3, connecting the test piece with a clamp; connecting two ends of a test piece 6 with a first tensile clamp 3 and a second tensile clamp 34 respectively through a strong adhesive and a rubber pad 25, then dividing a test area, measuring the length of the test area to be not less than 100mm, measuring and recording the section size at two ends and the middle part of the test area by using vernier calipers, installing grating displacement sensors 8 in the test area, and symmetrically distributing and arranging the grating displacement sensors 8 around the test piece 6 in a flush manner;
step 4, mounting a test piece; vertically arranging a first sliding T-shaped connecting piece 1 and a second sliding T-shaped connecting piece 2, respectively connecting and fixing sliding chutes of the two connecting pieces with an MTS actuator 11 and a loading table top 13, adjusting the position of the T-shaped connecting piece through a steel roller, ensuring the central lines of an upper T-shaped connecting piece and a lower T-shaped connecting piece to be superposed through an infrared vertical instrument, and then screwing a fixing clamping groove to fix the T-shaped connecting piece; connecting a tension sensor 7, a first floating spherical hinge 4, a first tensile fixture 3 and a test piece 6 with a first sliding T-shaped connecting piece 1 in sequence, connecting a second floating spherical hinge 5 with a second sliding T-shaped connecting piece 2 to enable the test piece 6 to be in a free plumb state, connecting a Y-shaped joint 26 and an I-shaped joint 27 with a second tensile fixture 34 and the second floating spherical hinge 5 respectively, and inserting a cylindrical pin 9 to complete the connection and installation of the test piece 6 and loading equipment; adjusting the initial stretching state by adjusting the screw distance between the second floating spherical hinge 5 and the Y-shaped joint 26 and the I-shaped joint 27;
Claims (10)
1. The direct tensile test device for the hydraulic asphalt concrete is characterized by comprising a support frame body, wherein a horizontal cross beam (15) is arranged at the top of the support frame body, a loading table top (13) parallel to the cross beam (15) is arranged at the bottom of the support frame body, the bottom of the cross beam (15) is connected with an MTS actuator (11), the bottom of the MTS actuator (11) is connected with a first sliding T-shaped connecting piece (1), and the first sliding T-shaped connecting piece (1) is connected with a first tensile clamp (3) through a first floating spherical hinge (4); a tension sensor (7) is also arranged between the first sliding T-shaped connecting piece (1) and the first floating spherical hinge (4);
the top of the loading table top (13) is connected with a loading platform base (12), one end, far away from the loading table top (13), of the loading platform base (12) is connected with a second sliding T-row connecting piece (2), the second sliding T-row connecting piece (2) is connected with a second stretching clamp (34) through a second floating spherical hinge (5), the first stretching clamp (3) is opposite to the second stretching clamp (34), and all the parts are located on central axes of the cross beam (15) and the loading table top (13); the device is characterized by further comprising a test piece (6), wherein the test piece (6) is clamped between the first tensile clamp (3) and the second tensile clamp (34), the test piece (6) is further provided with a grating displacement sensor (8), the device further comprises a high-temperature and low-temperature environment box (10), and the test piece (6) is located in the high-temperature and low-temperature environment box (10).
2. The direct tensile test device of hydraulic asphalt concrete according to claim 1, wherein the support frame body further comprises two steel columns (14) arranged in parallel, the two steel columns (14) are located between the cross beam (15) and the loading platform (13), and the steel columns (14) are perpendicular to the cross beam (15).
3. The direct tensile test device of hydraulic asphalt concrete according to claim 1, wherein the first sliding T-shaped connecting piece (1) comprises a first sliding groove (16) and a first clamping groove (17), the first sliding groove (16) is fixedly connected with the MTS actuator (11), the direct tensile test device further comprises a first T-shaped connecting piece (20), the horizontal end of the first T-shaped connecting piece (20) is embedded into the first clamping groove (17), a plurality of steel rollers (18) are further arranged on the inner side of the first clamping groove (17), and the first T-shaped connecting piece (20) is movably connected with the first clamping groove (17) through the steel rollers (18); screw hole (19) have been seted up to the vertical end tip of first T type connecting piece (20), and screw hole (19) are embedded to have a screw rod, and first T type connecting piece (20) are passed through screw rod and first ball pivot (4) fixed connection that float, and force sensor (7) are located the vertical end of first T type connecting piece (20).
4. The direct tensile test device of hydraulic asphalt concrete according to claim 3, wherein fastening bolts (23) are respectively arranged on two sides of the outer part of the first clamping groove (17), and the fastening bolts extend into the first clamping groove (17) and are connected with the first T-shaped connecting piece (20).
5. The direct tensile test device of hydraulic asphalt concrete according to claim 3, wherein the second sliding T-shaped connecting piece (2) has the same structure as the first sliding T-shaped connecting piece (2), a chute of the second sliding T-shaped connecting piece (2) extends into the loading platform base (12) to be fixedly connected with the loading platform base (12), and a T-shaped connecting piece of the second sliding T-shaped connecting piece (2) is connected with the second floating spherical hinge (5).
6. The direct tensile test device of hydraulic asphalt concrete of claim 1, wherein the first tensile clamp (3) comprises a C-shaped clamp (22) and side plates (21) positioned on two sides of the C-shaped clamp (22), the side plates (21) are connected with the C-shaped clamp (22) through bolts (35), a screw hole is further formed in the bottom of the C-shaped clamp (22), a screw rod is embedded into the screw hole, and one end, away from the first sliding T-shaped connecting piece (2), of the first floating spherical hinge (4) is fixedly connected with the first tensile clamp (3) through the screw rod.
7. The direct tensile test device of hydraulic asphalt concrete of claim 1, characterized in that, the tensile anchor clamps of second (34) is the same with first tensile anchor clamps (3) structure, and tensile anchor clamps of second (34) bottom is connected with Y type through the screw hole and connects (26), the open end of Y type joint (26) is embedded to have I type to connect (27), still includes cylinder pin (9), cylinder pin (9) pass Y type joint (26) and I type joint (27) fixed Y type joint (26) and I type joint (27) in proper order, and the one end that Y type joint (26) was kept away from in I type joint (27) is connected with the one end that second slip T line connecting piece (2) was kept away from in second ball pivot (5) that floats.
8. The direct tensile test device of hydraulic asphalt concrete according to claim 6 or 7, wherein the test piece (6) is a dumbbell type test piece, the height and width dimension B of the test area of the test piece is 3 to 5 times of the maximum aggregate, the length-width ratio L/B of the test area is 1.2 to 1.5, the ratio of the total length L of the test piece to the middle width B of the test area is 3.5 to 4.5, the ratio of the total length L to the end width B of the test piece is 2.5 to 3, and the side slope n is 2.5 to 4; the test piece (6) is located between the first tensile clamp (3) and the second tensile clamp (34), one end of the test piece (6) is embedded into the C-shaped clamp (22) of the clamps, the test piece (6) is fixedly connected with the C-shaped clamp (22) through a strong adhesive layer (24), and a rubber pad (25) is further arranged between the side plate (21) and the test piece (6).
9. The direct tensile test device of hydraulic engineering asphalt concrete of claim 1, characterized in that, high low temperature environment case (10) bottom both ends still are connected with crane (30) respectively, crane (30) are fixed in and are located loading platform base (12) both sides on loading mesa (13), and high low temperature environment case (10) bottom both sides still are connected with wheel (29), and crane (30) and high low temperature environment case (10) junction tip are provided with guide rail (28), guide rail (28) are embedded to have the draw-in groove, and wheel (29) are located guide rail (28) and cooperate with the guide rail.
10. An application method of a hydraulic engineering asphalt concrete direct tensile test device is characterized in that the hydraulic engineering asphalt concrete direct tensile test device is adopted according to claims 1-9, and the application method is implemented according to the following steps:
step 1, forming a test piece: forming in a laboratory or on site;
the specific process of on-site forming is as follows: the on-site core drilling sampling preparation is carried out, firstly, a drill bit with the inner diameter not smaller than 150mm is used for drilling a sample with the length not smaller than 320mm, and then, the sample is cut according to the shape of the test piece (6); the length, width and height size deviations of the test piece obtained by the method are +/-2 mm, +/-1 mm and +/-1 mm respectively;
the specific process of laboratory forming is as follows: at first, make up forming die, forming die includes two shaping curb plates (32), two end plates (31) and bottom plate (33), all through bolted connection between the plywood piece, shaping curb plate (32) center department be provided with test piece (6) complex protruding, the shaping technology is the two-sided real shaping of hitting of individual layer, concrete step is: firstly mixing an asphalt mixture, heating a forming die to 100-110 ℃ when the temperature range of the asphalt mixture is 145-155 ℃, coating a release agent, feeding the prepared asphalt mixture into the forming die, placing a flat plate on the upper part after the asphalt mixture is flattened, adjusting the flatness of the asphalt mixture by observing a leveling bead, pulling a compaction hammer to a preset height to freely fall down, compacting the test piece uniformly, then installing a bottom plate (33) in the forming die on the upper part, overturning the test piece, compacting the test piece for the second time by adopting the same steps, and compacting the test piece for the second time by taking the density of the test piece as the standard of +/-1% of the density of a Marshall standard compacted test piece, wherein the height size deviation is +/-1 mm;
step 2, polishing the test piece (6), removing the mold after the test piece (6) is naturally cooled, polishing the connecting area of the end part of the test piece (6), polishing the upper end surface and the lower end surface of the test piece to be flat, and polishing the side surface and the inclined surface to be a honeycomb pitted surface;
step 3, connecting the test piece with a clamp; connecting two ends of a test piece (6) with a first tensile clamp (3) and a second tensile clamp (34) respectively through a strong adhesive and a rubber pad (25), then dividing a test area, measuring and recording the section size at two ends and the middle part of the test area by using vernier calipers, mounting grating displacement sensors (8) in the test area, and symmetrically distributing and leveling the grating displacement sensors (8) around the test piece (6);
step 4, mounting a test piece; vertically arranging a first sliding T-shaped connecting piece (1) and a second sliding T-shaped connecting piece (2), respectively connecting and fixing sliding chutes of the two connecting pieces with an MTS actuator (11) and a loading table top (13), adjusting the positions of the T-shaped connecting pieces through steel rollers, ensuring the central lines of the upper and lower T-shaped connecting pieces to be overlapped through an infrared vertical instrument, and then screwing and fixing clamping grooves to fix the T-shaped connecting pieces; sequentially connecting a tension sensor (7), a first floating spherical hinge (4), a first tensile fixture (3) and a test piece (6) with a first sliding T-shaped connecting piece (1), connecting a second floating spherical hinge (5) with a second sliding T-shaped connecting piece (2), enabling the test piece (6) to be in a free plumb state, respectively connecting a Y-shaped joint (26) and an I-shaped joint (27) with a second tensile fixture (34) and a second floating spherical hinge (5), and inserting a cylindrical pin (9) to complete the connection and installation of the test piece (6) and loading equipment; adjusting the initial stretching state by adjusting the screw distance between the second floating spherical hinge (5) and the Y-shaped joint (26) and the I-shaped joint (27);
step 5, test preloading; connecting a tension sensor (7) and a grating displacement sensor (8) into an acquisition system, checking each test device, debugging an MTS actuator (11), setting a loading system, preloading at room temperature, wherein the preloading range is 20-40% of the tensile strength of the hydraulic asphalt concrete, and when the reading of the displacement sensor is uniformly changed, carrying out the next step, or debugging a test piece connecting system again until the preloading condition is met;
step 6, carrying out constant temperature test piece; fixing the high-temperature environment (10) and the low-temperature environment through a fixed clamping groove, setting the test temperature, and keeping the temperature of the test piece (6) constant for not less than 6 hours; if the test temperature is not specially specified, the annual average temperature of the engineering place or 20 ℃ and 5 ℃ can be adopted;
step 7, carrying out formal loading on the test; after the preparation of the steps is finished, performing a tensile test according to a set loading system, recording data of the tension sensor and the displacement sensor in the test process until the test piece is loaded and damaged, calculating information such as tensile strength and deformation, and drawing a tensile stress-strain curve.
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