CN108196039B - Device and method for simulating crack characteristics among broken blocks and influence of crack characteristics on layering - Google Patents
Device and method for simulating crack characteristics among broken blocks and influence of crack characteristics on layering Download PDFInfo
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- CN108196039B CN108196039B CN201810212947.7A CN201810212947A CN108196039B CN 108196039 B CN108196039 B CN 108196039B CN 201810212947 A CN201810212947 A CN 201810212947A CN 108196039 B CN108196039 B CN 108196039B
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- 238000000034 method Methods 0.000 title claims abstract description 13
- 238000012360 testing method Methods 0.000 claims abstract description 74
- 239000004567 concrete Substances 0.000 claims abstract description 66
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000004568 cement Substances 0.000 claims abstract description 50
- 239000002131 composite material Substances 0.000 claims abstract description 41
- 238000004088 simulation Methods 0.000 claims abstract description 35
- 230000007246 mechanism Effects 0.000 claims description 38
- 239000011384 asphalt concrete Substances 0.000 claims description 27
- 238000001125 extrusion Methods 0.000 claims description 23
- 230000005484 gravity Effects 0.000 claims description 18
- 230000001133 acceleration Effects 0.000 claims description 15
- 239000010426 asphalt Substances 0.000 claims description 12
- 238000003860 storage Methods 0.000 claims description 12
- 238000005520 cutting process Methods 0.000 claims description 10
- 238000011161 development Methods 0.000 claims description 10
- 230000000694 effects Effects 0.000 claims description 9
- 239000011265 semifinished product Substances 0.000 claims description 9
- 238000005096 rolling process Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000000149 penetrating effect Effects 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 229920006332 epoxy adhesive Polymers 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 3
- 230000007480 spreading Effects 0.000 claims description 3
- 238000003892 spreading Methods 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 claims description 3
- 238000009825 accumulation Methods 0.000 abstract description 4
- 238000013461 design Methods 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 4
- 230000001808 coupling effect Effects 0.000 abstract description 3
- 239000010410 layer Substances 0.000 description 67
- 230000006378 damage Effects 0.000 description 6
- 230000007613 environmental effect Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 3
- 230000008439 repair process Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
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- 230000008859 change Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
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- 239000002344 surface layer Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
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- G01N33/383—Concrete or cement
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention provides a simulation device and a simulation method for crack characteristics among broken blocks and influence of the crack characteristics on paving layers, wherein the simulation device comprises an environment box, a base is arranged at the lower part of the environment box, a composite layer test piece with prefabricated cracks is arranged at the middle part of the base, and a constraint frame is sleeved on the composite layer test piece; the two sides of the lower part of the composite layer test piece are provided with horizontal direction loading devices, the upper part of the composite layer test piece is provided with a paving layer loading device and a rainfall simulation device, the lower part of the paving layer loading device is fixed on the base, and the horizontal direction loading device, the rainfall simulation device and the paving layer loading device are all connected with the acquisition control system. The invention can simulate the influence of the coupling effect of factors such as driving load, temperature, water and the like on the composite structure; the method can simulate the embedding and squeezing force of the blocks and the crack form among the blocks to develop the upper paving crack truly, and provides technical support and accumulation for the crack resistance of the rubblizing technology and the reconstruction design of old cement concrete pavement of road engineering.
Description
Technical Field
The invention relates to the technical field of road engineering, mainly relates to old cement concrete road transformation, in particular to a simulation device and a simulation method for crack characteristics among broken blocks and influence of the broken blocks on paving, and is used for simulating and evaluating the influence of embedding and extrusion biting force among broken blocks of cement concrete and crack forms among blocks on development of upper asphalt paving cracks.
Background
Cement concrete pavement is one of the important forms of pavement structures in China. Under the current rapidly growing traffic conditions in China, the cement concrete pavement starts to be damaged seriously in a large area, and the repair and transformation of the cement concrete pavement are urgent. The cement concrete pavement rubblizing technology can effectively inhibit the occurrence of road cracks.
At present, due to the problems of overload, insufficient maintenance and the like of the existing cement concrete pavement in China during the use period, a considerable part of the existing cement concrete pavement approaches or exceeds the design age limit of the existing cement concrete pavement, and more old cement concrete pavement is subjected to repair work. The asphalt pavement not only has good travelling comfort, but also is easier to repair than the cement concrete pavement, so that the asphalt layer is additionally paved on the old cement concrete pavement, and the asphalt pavement is an effective measure for improving the service performance of the old cement concrete pavement.
The damage of the asphalt concrete pavement is mainly caused by the original defect of the crack or seam of the old cement concrete pavement and the damage, and the stress concentration and the internal damage of the asphalt concrete pavement are caused, and the main appearance form of the damage is asphalt pavement crack. Road cracks not only can influence driving comfort, but also can lead to the road surface to be immersed under water, and influence the strength and stability of the roadbed. More importantly, under the influence of repeated action of running load and periodically changing environmental temperature, cracks are often caused to rapidly spread to the periphery, and the service life of the asphalt surface layer is greatly shortened.
For the problem of cracks of asphalt paving layers in old road reconstruction, a comprehensive test method and reliable evaluation indexes still lack at present, and the influence of the embedding extrusion force between cement concrete blocks and the crack form on the upper paving layers under the actual working condition cannot be systematically reduced.
Disclosure of Invention
Aiming at the technical problem that the impact of the inter-block embedding extrusion force and inter-block crack form on the development of upper paving cracks after the cement concrete pavement is not deeply researched and simulated, the invention provides a simulation device and a simulation method for the characteristics of the cracks among broken blocks and the impact on the paving, which are used for simulating and grading the impact of the inter-block embedding extrusion force and inter-block crack form of the cement concrete on the development of upper paving cracks; the development of the layered cracks is reduced by evaluating how to crack and how to roll by the road roller through the crack expansion rate, strain and destruction stress, and technical support and accumulation are provided for practical engineering.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows: the device comprises an environment box, wherein a base is arranged at the lower part of the environment box, a composite layer test piece with prefabricated cracks is arranged in the middle of the base, and a constraint frame is sleeved on the composite layer test piece; the two sides of the lower part of the composite layer test piece are provided with horizontal direction loading devices, the upper part of the composite layer test piece is provided with a paving loading device and a rainfall simulation device, the lower part of the paving loading device is fixed on the base, and the horizontal direction loading device, the rainfall simulation device and the paving loading device are all connected with the acquisition control system.
The composite layer test piece comprises a precast split concrete beam provided with a precast split and an asphalt concrete paving layer, wherein the asphalt concrete paving layer is arranged on the upper part of the precast split concrete beam; the upper part of the asphalt concrete paving layer is provided with a strain gauge which is arranged below the paving layer loading device and connected with the acquisition control system; the prefabricated cracks are vertical cracks, oblique cracks or V-shaped cracks.
The manufacturing method of the composite layer test piece comprises the following steps: pouring a cement concrete beam, and cutting the middle part of the cement concrete beam to obtain a prefabricated crack after the cement concrete beam reaches a curing age; after cutting, adhering the base to the middle of the base by using an epoxy adhesive to form a test piece, and fixing the constraint frame on the test piece; setting a horizontal loading device to load the two sides of the broken cement concrete layer, loading the two sides of the cement concrete after cutting cracks, simulating block embedding extrusion force, and stabilizing for 1h until the self-adaptive stage is stable; uniformly spreading penetrating layer oil on the upper part of the cement concrete after the crack is cut, and standing for 2h at room temperature to form a semi-finished product test piece; and paving the mixed asphalt mixture on a semi-finished product test piece to form a paving layer, rolling the semi-finished product test piece by using a loading wheel of an upper paving layer loading device, firstly rolling for 2 times in one direction, continuously compacting for 24 times after rotating for 90 degrees, then placing the test piece at room temperature for 48 hours, and pasting three strain gauges on the middle part of the paving layer to finish the sample preparation of the composite layer test piece.
The restraint frame is a transparent detachable frame body with openings on the upper surface and the lower surface and openings on the lower parts of the two side surfaces.
The horizontal direction loading device comprises a horizontal power system, a connecting beam, a loading plate and a transverse load sensor, wherein the loading plate is vertically arranged on two sides of the precast split concrete beam, the loading plate is connected with the connecting beam, and the connecting beam is connected with the horizontal power system; and the connecting beam is provided with a transverse load sensor which is connected with the acquisition control system.
The layering loading device comprises a support platform, a stand column, a horizontal shaft, a cross rod, a vertical load sensor, a vertical loading shaft and a loading wheel, wherein the lower part of the stand column is fixed on a base, the upper part of the stand column is fixed with the horizontal shaft, the horizontal shaft is connected with the support platform through a sliding block, and the support platform is provided with a horizontal driving mechanism and a vertical loading mechanism; the vertical loading mechanism is connected with a cross rod arranged below the horizontal shaft, the lower part of the cross rod is fixedly provided with a vertical loading shaft, the lower part of the vertical loading shaft is movably connected with a loading wheel, the vertical loading sensor is arranged on the vertical loading shaft, and the vertical loading sensor is connected with the acquisition control system.
The horizontal driving mechanism comprises a prime motor, a connecting rod mechanism and an acceleration sensor, wherein the prime motor is connected with the connecting rod mechanism, the connecting rod mechanism is connected with one end of the support platform, the acceleration sensor is arranged on the connecting rod mechanism, and the prime motor and the acceleration sensor are both connected with the acquisition control system; and limiting springs for limiting the horizontal movement range of the support platform are arranged at two ends of the horizontal shaft.
The vertical loading mechanism comprises a gravity loading device, a guide pillar and a jack, wherein the jack and a guide sleeve matched with the guide pillar are fixed on the support platform, the gravity loading device is fixed on the upper part of the guide pillar, and the jack is positioned below the middle part of the gravity loading device; the lower part of the guide post is fixedly connected with the cross rod.
The rainfall simulation device comprises a water guide pipe, a pressure sensor, an air compressor, a water storage tank and a water outlet pipe, wherein the water guide pipe and the air compressor are connected with the water storage tank, the water guide pipe is connected with the water outlet pipe, and the water outlet pipe passes through the support platform and is arranged above the loading wheel; and a pressure sensor is arranged between the air compressor and the water storage tank, and the pressure sensor and the air compressor are connected with the acquisition control system.
The method for simulating the expansion of the crack of the upper paving layer by adopting the simulation device and adopting the embedding extrusion force between the blocks of the cement concrete and the crack form between the blocks comprises the steps of S1, manufacturing and fixing a composite layer test piece according to the crack form between the blocks of the cement concrete and the embedding extrusion force, and applying the embedding extrusion occlusion effect of a horizontal direction loading device on a precast cracked concrete beam; s2, the acquisition control system sets the test temperature in the environment box through a refrigerator at the upper part of the environment box and a heating device at the lower part of the environment box, controls the water flow rate of the rainfall simulation device, and controls the horizontal driving mechanism and the vertical loading mechanism to respectively adjust the speed and the load of the loading wheel; s3, starting the paving layer loading device until the simulation is finished, enabling the loading wheel to reciprocate left and right on the asphalt concrete paving layer, generating horizontal and vertical acting forces on the asphalt concrete paving layer simultaneously, generating water flow by the rainfall simulation device, and evaluating the influence of the block embedding extrusion force and the inter-block crack form on crack development of the upper asphalt concrete paving layer.
The invention has the beneficial effects that: the influence of the environmental temperature on the test piece is simulated, the effect of precipitation is considered, and the influence of the coupling effect of factors such as driving load, temperature, water and the like on the composite structure can be simulated; the effect of different vehicle speeds and different load vehicles on the paving layer can be simulated; the application range is wide, different crack forms and different front extrusion biting forces can exist in the tested composite structure, and the tested composite structure material can be changed; the method can simulate the embedding and squeezing force of the blocks and the crack form among the blocks to develop the upper paving crack truly, and provides technical support and accumulation for the crack resistance of the rubblizing technology and the reconstruction design of old cement concrete pavement of road engineering.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural view of the present invention.
Fig. 2 is a schematic structural view of a constraint frame of the present invention.
Wherein, 1, prime mover; 2. a link mechanism; 3. an acceleration sensor; 4. a gravity loading device; 5. a guide post; 6. a jack; 7. a support platform; 8. a water conduit; 9. a pressure sensor; 10. an air compressor; 11. a water storage tank; 12. a limit spring; 13. a horizontal axis; 14. a cross bar; 15. a water outlet pipe; 16. a vertical loading shaft; 17. a vertical load sensor; 18. a loading wheel; 19. a constraint frame; 20. paving asphalt concrete; 21. prefabricating a slit concrete beam; 22. a strain gage; 23. prefabricating cracks; 24. a lateral load sensor; 25. a connecting beam; 26. a horizontal power system; 27. a base; 28. the acquisition control system; 29. an environmental box; 30. a loading plate; 31. and (5) a column.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without any inventive effort, are intended to be within the scope of the invention.
As shown in FIG. 1, the simulation device for the crack characteristics among broken blocks and the influence of the crack characteristics on the added layers comprises an environment box 29, wherein a base 27 is arranged at the lower part of the environment box 29, a composite layer test piece with prefabricated cracks is arranged at the middle part of the base 27, and a constraint frame 19 is sleeved on the composite layer test piece; the both sides of composite bed test piece lower part are equipped with horizontal direction loading device, and the upper portion of composite bed test piece is equipped with and adds layering loading device and rainfall simulation device, and the lower part that adds layering loading device is fixed on base 27, and horizontal direction loading device, rainfall simulation device and layering loading device are all connected with collection control system 28. The horizontal direction loading device and the layering loading device can act on the composite layer test piece at the same time, but the horizontal direction loading device and the layering loading device do not affect each other. The acquisition control system 28 adjusts the corresponding power plant to achieve the corresponding control by measuring the acceleration of the horizontal motion, the magnitude of the lateral and vertical loads, and the flow rate of the water. The environment tank 29 is provided with a temperature control device, which includes a refrigerator provided at an upper portion in the environment tank 29 and a heating device provided at a lower portion in the environment tank 29. The temperature control device can simulate working conditions of different temperatures, including working conditions of severe cold freezing and hot high temperature.
The composite layer test piece comprises a precast split concrete beam 21 provided with a precast split 23 and an asphalt concrete paving layer 20, wherein the asphalt concrete paving layer 20 is arranged on the upper part of the precast split concrete beam 21; the upper part of the asphalt concrete paving layer 20 is provided with a strain gauge 22, the strain gauge 22 is arranged below the paving layer loading device, the strain gauge 22 is connected with the acquisition control system 28, and the strain gauge 22 senses the strain force acted on the upper paving layer loading device and transmits only the acquisition control system 28.
The manufacturing method of the composite layer test piece comprises the following steps: firstly pouring a cement concrete beam, and cutting the middle part of the cement concrete beam to obtain a prefabricated crack 23 after the cement concrete beam reaches a curing age, wherein the prefabricated crack 23 is a common vertical crack, an oblique crack or a V-shaped crack and the like; after cutting, adhering the base 27 to the middle part of the base by using an epoxy adhesive to form a test piece, and fixing the constraint frame 19 on the test piece; setting a horizontal loading device to load the two sides of the broken cement concrete layer, loading the two sides of the cement concrete after cutting cracks, simulating block embedding extrusion force, and stabilizing for 1h until the self-adaptive stage is stable; uniformly spreading penetrating layer oil on the upper part of the cement concrete after the crack is cut, and standing for 2h at room temperature to form a semi-finished product test piece; and paving the mixed asphalt mixture on a semi-finished product test piece to form a paving layer, rolling the semi-finished product test piece by using a loading wheel of an upper paving layer loading device, firstly rolling for 2 times in one direction, continuously compacting for 24 times after rotating for 90 degrees, then placing the test piece at room temperature for 48 hours, and pasting three strain gauges 22 in the middle of the paving layer to finish the sample preparation of the composite layer test piece.
As shown in fig. 2, the restraining frame 19 is a transparent detachable frame with an opening on the upper surface and the lower surface and an opening on the lower part of the two side surfaces. The front and rear surfaces of the restraint frame 19 are solid and can limit the composite test piece. The constraint frame 19 is closer to the actual working condition of the constraint around the actual pavement, the constraint frame 19 mainly plays a role in fixing and constraining the asphalt concrete paving layer 20 on the upper portion, and the constraint frame is transparent so as to observe the crack change of the asphalt concrete paving layer 20 in the test process.
The horizontal direction loading device comprises a horizontal power system 26, a connecting cross beam 25, a loading plate 30 and a transverse load sensor 24, wherein the loading plate 30 is vertically arranged on two sides of the precast split concrete beam 21, and the loading plate 30 is matched with openings on two sides of the constraint frame 19, so that limit constraint of the constraint frame 19 on a composite layer test piece is not affected. The loading plate 30 is connected with the connecting beam 25, and the connecting beam 25 is connected with the horizontal power system 26; the connecting beam 25 is provided with a transverse load sensor 24, and the transverse load sensor 24 is connected with an acquisition control system 28. The horizontal direction loading device can apply stable force to the crushed cement concrete layer through the loading plate 30 so as to ensure the embedding and extruding force between the blocks of the simulated precast split concrete beam 21.
The layering loading device comprises a support platform 7, a stand column 31, a horizontal shaft 13, a cross rod 14, a vertical load sensor 17, a vertical loading shaft 16 and loading wheels 18, wherein the lower part of the stand column 31 is fixed on a base 27, the horizontal shaft 13 is fixed on the upper part of the stand column 31, the horizontal shaft 13 is connected with the support platform 7 through a sliding block, the horizontal shaft 13 serves as a horizontal slideway, and the support platform 7 is connected to the upper part of the horizontal shaft 13 in a sliding mode. A horizontal driving mechanism and a vertical loading mechanism are arranged on the bracket platform 7; the vertical loading mechanism is connected with a cross rod 14 arranged below the horizontal shaft 13, a vertical loading shaft 16 is fixed at the lower part of the cross rod 14, a loading wheel 18 is movably connected at the lower part of the vertical loading shaft 16, a vertical load sensor 17 is arranged on the vertical loading shaft 16, and the vertical load sensor 17 is connected with an acquisition control system 28.
The horizontal driving mechanism comprises a prime motor 1, a connecting rod mechanism 2 and an acceleration sensor 3, wherein the prime motor 1 is connected with the connecting rod mechanism 2, the connecting rod mechanism 2 is connected with one end of a support platform 7, the acceleration sensor 3 is arranged on the connecting rod mechanism 2, and the prime motor 1 and the acceleration sensor 3 are both connected with an acquisition control system 28; two ends of the horizontal shaft 13 are provided with limiting springs 12 for limiting the horizontal movement range of the support platform 7, so that the loading wheels 18 are prevented from moving out of the composite layer test piece under the drive of the support platform 7, and the reliability of the whole device is improved. The prime motor 1 drives the support platform 7 to do reciprocating motion in the horizontal direction through the link mechanism 2, the moving acceleration of the support platform 7 is measured through the acceleration sensor 3, and the acquisition control system 28 controls the control speed of the prime motor 1 to simulate the effect of different vehicle speeds on the road surface.
The vertical loading mechanism comprises a gravity loading device 4, a guide column 5 and a jack 6, wherein the jack 6 and a guide sleeve matched with the guide column 5 are fixed on a support platform 7, the gravity loading device 4 is fixed on the upper part of the guide column 5, and the lower part of the guide column 5 is fixedly connected with a cross rod 14. The gravity load device 4 is connected with the cross bar 14 by two guide posts 5 penetrating through the bracket platform 7, and the jack 6 on the bracket platform 7 is a lifting adjusting device, so that a vertical load sensor 17 and a loading wheel 18 which are sequentially connected with the lower part of the cross bar 14 are adjusted. The jack 6 is located below the middle part of the gravity loading device 4, can be lifted upwards from the middle part of the gravity loading device 4, and ensures the stability in the adjusting process. The vertical pressure is realized through the jack 6 and the gravity load device 4, the jack 6 can be jacked to the gravity load device 4 through rotating a screw rod, so that the vertical pressure of the pressure adjusting cross rod 14 to the loading wheel 18 is generated, the load of the loading wheel 18 is measured by the cross rod 14 through the vertical load sensor 17 above the loading wheel 18, and the load of the loading wheel 18 can be controlled through adjusting the jack 6, so that the effect of different load vehicles is simulated. The gravity loading device 4 has a plurality of adjustable numbers of weights, so that adjustment of the different gravity loads of the loading wheel 18 is achieved.
The rainfall simulation device comprises a water guide pipe 8, a pressure sensor 9, an air compressor 10, a water storage tank 11 and a water outlet pipe 15, wherein the water guide pipe 8 and the air compressor 10 are connected with the water storage tank 11, the water guide pipe 8 is connected with the water outlet pipe 15, and the water outlet pipe 15 passes through the bracket platform 7 and is arranged above the loading wheel 18; a pressure sensor 9 is arranged between the air compressor 10 and the water storage tank 11, and the pressure sensor 9 and the air compressor 10 are connected with an acquisition control system 28. The water outlet pipe 15 is placed in the middle of the cross rod 14, the air compressor 10 can generate air pressure to press water into the water outlet pipe 15, and the pressure sensor 9 measures the air pressure output by the air compressor, so that the air compressor 10 is adjusted to control the water pressure through the acquisition control system 28, and different rainfall levels are simulated.
The working principle of the device is as follows: firstly, the horizontal direction loading device is controlled by the sampling stage acquisition control system 28 to set horizontal embedding and extrusion biting force, the horizontal power system 26 generates power, the connecting cross beam 25 transmits the horizontal force to the vertical loading plate 30, the loading plate 30 directly acts on the precast split concrete beam 21, namely the crushed cement concrete layer, and the horizontal load sensor 24 detects the load in the horizontal direction in real time, so that the horizontal embedding and extrusion force is stable. The upper refrigerator and the lower heating device in the environment tank 29 regulate the temperature therein. The prime motor 1 at the upper part drives the link mechanism 2 to drive the bracket platform 7 to reciprocate in the horizontal direction, the acquisition control system 28 detects the acceleration of the movement of the link mechanism 2 in real time through the acceleration sensor, the speed is controlled by adjusting the prime motor 1, and the limit springs 12 at the left and right ends of the horizontal shaft 13 control the left and right positions of the loading wheels 18. The vertical pressure is generated by the jack 6 by rotating the screw, which can be pushed up to the gravity loading device 4, and acts directly on the asphalt concrete paving layer 20 through the loading wheel 18. A vertical load sensor 17 is arranged above the loading wheel 18, and the load of the loading wheel 18 can be controlled by adjusting the elongation of the jack 6 and the weight of the counterweight block of the gravity load device 4. Meanwhile, the rainfall simulation device generates air pressure through the air compressor 10, the pressure sensor 9 detects the pressure in real time to adjust the air compressor 10 to control the water outlet flow rate, the water in the water storage tank 11 is pressed into the water outlet pipe, and the water flow acts on the asphalt concrete paving layer 20. The whole device generates stable horizontal force for crushing the cement concrete layer, the upper loading wheel 18 reciprocates left and right on the asphalt concrete paving layer 20, horizontal and vertical acting forces are generated on the asphalt concrete paving layer 20, meanwhile, the rainfall simulation device generates water flow, and finally, the influence of block mutual embedding extrusion force and block crack form on the development of upper paving layer cracks is evaluated.
The method for simulating the expansion of the crack of the upper paving layer by adopting the simulation device and adopting the embedding extrusion force between the blocks of the cement concrete and the crack form between the blocks comprises the steps of S1, manufacturing and fixing a composite layer test piece according to the crack form between the blocks of the cement concrete and the embedding extrusion force, wherein the size of the composite layer test piece is based on a constraint frame which can be placed at the lower part of a support platform, and carrying out embedding extrusion occlusion on a precast cracked concrete beam 21 in the horizontal direction by a horizontal direction loading device; s2, according to a specific test type, the acquisition control system 28 sets a test temperature in the environment box 29 through a refrigerator at the upper part of the environment box and a heating device at the lower part of the environment box, the acquisition control system 28 controls the water flow rate of the rainfall simulation device, the acquisition control system 28 controls a horizontal driving mechanism and a vertical loading mechanism to respectively adjust the speed and the load of the loading wheel 18, and a corresponding switch and a computer controller are opened; s3, starting the paving layer loading device until the simulation is finished, enabling the loading wheel 18 to reciprocate left and right on the asphalt concrete paving layer 20, generating horizontal and vertical acting forces on the asphalt concrete paving layer 20, simultaneously simulating water flow generated by the rainfall device, obtaining time and length in crack development and strain and damage stress in crack development through computer control, and evaluating influence of block embedding extrusion force and inter-block crack form on crack development of the upper asphalt concrete paving layer 20.
In the test, the test ending conditions such as the loading cycle number N, strain values at two ends of the crack or crack breaking stress can be set according to different requirements, and after the test is finished, data can be exported to the storage equipment for further data analysis.
Further, in step S1, the specific process of preparing the composite layer test piece includes:
s11, pouring a concrete beam with the size capable of being placed in the lower half part of the fixed constraint frame 19, cutting a prefabricated crack in the middle of the beam after the beam reaches the curing age, and specifically designing the form of the prefabricated crack according to the requirements of different tests;
step S12, placing the cement concrete beam with the crack cut in a constraint frame at the bottom, starting a horizontal loading device below a bracket platform 7 to enable the crack to be tightly attached, simultaneously smearing epoxy adhesive at the bottom of a test piece to fix the test piece on an experiment platform, and standing for more than 1h until the state of the test piece is stable;
step S13, uniformly spraying a layer of penetrating oil on the upper part of the cement concrete beam, standing and cooling for more than 2 hours at room temperature;
step S14, adding the uniformly mixed asphalt mixture into the constraint frame on which the cement concrete beam is placed, and primarily compacting the asphalt mixture;
step S15, rolling the sample by using a loading wheel 18 in a vertical loading mechanism, wherein the rolling is performed for 2 times in one direction; continuously compacting for 24 times after rotating for 90 degrees to obtain a finally formed sample;
and S16, placing the prepared sample at normal temperature and normal pressure for 48 hours, and performing subsequent test steps.
The termination conditions for the end of the experiment of simulating the horizontally-opened reflective crack by the reflective crack are as follows: 1. the set cyclic loading times are reached; 2. breaking the crack penetrating surface of the test piece to be tested; 3. the middle part of the test piece to be tested reaches a set strain value; 4. the middle part of the test piece to be tested reaches a set stress value; 5. the middle part of the test piece to be tested is damaged. The final evaluation was performed by its cycle N, crack propagation rate: μ=h/T, fracture end strain epsilon, failure stress sigma=e ∙ epsilon, and the like.
In the invention, one period of crack simulation is that the maximum displacement is reached from the initial distance and then the initial position is returned to be one period, and the time taken by one period can be adjusted. The device has wide application range, different crack forms and different front extrusion biting forces can exist in the tested composite layer test piece, and the materials of the tested composite layer test piece can be changed.
The invention not only simulates the influence of the environmental temperature on the test piece, but also considers the effect of precipitation, and can simulate the influence of the coupling effect of factors such as driving load, temperature, water and the like on the test piece of the composite layer. The invention can simulate the effect of different vehicle speeds and different on-load vehicles on layering. The invention can simulate the embedding and squeezing force of the blocks and the crack form among the blocks to develop the upper paving crack in a true close way, and provides technical support and accumulation for crack resistance of the rubblizing technology and the reconstruction design of old cement concrete pavement of road engineering.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (4)
1. The device for simulating crack characteristics among broken blocks and the influence of the crack characteristics on the added layers comprises an environment box (29), and is characterized in that a base (27) is arranged at the lower part of the environment box (29), a composite layer test piece for prefabricating cracks is arranged at the middle part of the base (27), and a constraint frame (19) is sleeved on the composite layer test piece; the two sides of the lower part of the composite layer test piece are provided with horizontal direction loading devices, the upper part of the composite layer test piece is provided with a paving layer loading device and a rainfall simulation device, the lower part of the paving layer loading device is fixed on a base (27), and the horizontal direction loading device, the rainfall simulation device and the paving layer loading device are all connected with an acquisition control system (28);
the composite layer test piece comprises a precast split concrete beam (21) provided with a precast split (23) and an asphalt concrete paving layer (20), wherein the asphalt concrete paving layer (20) is arranged on the upper part of the precast split concrete beam (21); the upper part of the asphalt concrete paving layer (20) is provided with a strain gauge (22), the strain gauge (22) is arranged below the paving layer loading device, and the strain gauge (22) is connected with the acquisition control system (28); the prefabricated cracks (23) are vertical cracks, oblique cracks or V-shaped cracks;
the constraint frame (19) is a transparent detachable frame body with openings on the upper surface and the lower surface and openings on the lower parts of the two side surfaces;
the rainfall simulation device comprises a water guide pipe (8), a pressure sensor (9), an air compressor (10), a water storage tank (11) and a water outlet pipe (15), wherein the water guide pipe (8) and the air compressor (10) are connected with the water storage tank (11), the water guide pipe (8) is connected with the water outlet pipe (15), and the water outlet pipe (15) passes through a support platform (7) of the layering loading device and is arranged above a loading wheel (18); a pressure sensor (9) is arranged between the air compressor (10) and the water storage tank (11), and the pressure sensor (9) and the air compressor (10) are connected with an acquisition control system (28);
the manufacturing method of the composite layer test piece comprises the following steps: pouring a cement concrete beam, and cutting the middle part of the cement concrete beam to obtain a prefabricated crack (23) after the cement concrete beam reaches a curing age; after cutting, adhering the base (27) to the middle part of the base by using an epoxy adhesive to form a test piece, and fixing the constraint frame (19) on the test piece; setting a horizontal loading device to load the two sides of the broken cement concrete layer, loading the two sides of the cement concrete after cutting cracks, simulating block embedding extrusion force, and stabilizing for 1h until the self-adaptive stage is stable; uniformly spreading penetrating layer oil on the upper part of the cement concrete after the crack is cut, and standing for 2h at room temperature to form a semi-finished product test piece; paving the mixed asphalt mixture on a semi-finished product test piece to form a paving layer, rolling the semi-finished product test piece by using a loading wheel of an upper paving layer loading device, firstly rolling for 2 times in one direction, continuously compacting for 24 times after rotating for 90 degrees, then placing the test piece at room temperature for 48 hours, and pasting three strain gauges (22) on the middle part of the paving layer to finish the sample preparation of the composite layer test piece;
the horizontal direction loading device comprises a horizontal power system (26), a connecting cross beam (25), a loading plate (30) and a transverse load sensor (24), wherein the loading plate (30) is vertically arranged on two sides of the precast split concrete beam (21), the loading plate (30) is connected with the connecting cross beam (25), and the connecting cross beam (25) is connected with the horizontal power system (26); a transverse load sensor (24) is arranged on the connecting cross beam (25), and the transverse load sensor (24) is connected with an acquisition control system (28);
the layering loading device comprises a support platform (7), a vertical column (31), a horizontal shaft (13), a cross rod (14), a vertical load sensor (17), a vertical loading shaft (16) and a loading wheel (18), wherein the lower part of the vertical column (31) is fixed on a base (27), the horizontal shaft (13) is fixed on the upper part of the vertical column (31), the horizontal shaft (13) is connected with the support platform (7) through a sliding block, and a horizontal driving mechanism and a vertical loading mechanism are arranged on the support platform (7); the vertical loading mechanism is connected with a cross rod (14) arranged below the horizontal shaft (13), a vertical loading shaft (16) is fixed at the lower part of the cross rod (14), a loading wheel (18) is movably connected at the lower part of the vertical loading shaft (16), a vertical load sensor (17) is arranged on the vertical loading shaft (16), and the vertical load sensor (17) is connected with an acquisition control system (28).
2. The simulation device for the crack characteristics among broken blocks and the influence on the layering according to claim 1, wherein the horizontal driving mechanism comprises a prime motor (1), a connecting rod mechanism (2) and an acceleration sensor (3), the prime motor (1) is connected with the connecting rod mechanism (2), the connecting rod mechanism (2) is connected with one end of a support platform (7), the acceleration sensor (3) is arranged on the connecting rod mechanism (2), and the prime motor (1) and the acceleration sensor (3) are connected with an acquisition control system (28); and limiting springs (12) used for limiting the horizontal movement range of the support platform (7) are arranged at two ends of the horizontal shaft (13).
3. The simulation device for the crack characteristics among broken blocks and the influence on the layering according to claim 2, wherein the vertical loading mechanism comprises a gravity loading device (4), a guide pillar (5) and a jack (6), the jack (6) and a guide sleeve matched with the guide pillar (5) are fixed on a bracket platform (7), the gravity loading device (4) is fixed on the upper part of the guide pillar (5), and the jack (6) is positioned below the middle part of the gravity loading device (4); the lower part of the guide post (5) is fixedly connected with the cross rod (14).
4. A method for simulating crack characteristics between crushed cement concrete blocks and their effect on paving by using the simulation device according to any one of claims 1 to 3, characterized in that: s1, manufacturing and fixing a composite layer test piece according to crack forms and embedding extrusion forces among cement concrete blocks, and applying a horizontal embedding extrusion occlusion effect on a precast cracked concrete beam (21) by a horizontal direction loading device; s2, a collection control system (28) sets a test temperature in an environment box (29) through a refrigerator at the upper part of the environment box and a heating device at the lower part of the environment box, the collection control system (28) controls the water flow rate of the rainfall simulation device, and the collection control system (28) controls a horizontal driving mechanism and a vertical loading mechanism to respectively adjust the speed and the load of a loading wheel (18); s3, starting the paving layer loading device until the simulation is finished, enabling the loading wheel (18) to reciprocate left and right on the asphalt concrete paving layer (20), generating horizontal and vertical acting forces on the asphalt concrete paving layer (20) simultaneously, generating water flow by the rainfall simulation device, and evaluating the influence of the block embedding extrusion force and the inter-block crack form on crack development of the upper asphalt concrete paving layer (20).
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| CN111289391B (en) * | 2020-03-12 | 2022-09-09 | 长沙理工大学 | Reciprocating movement loading test system for testing roadbed and pavement deformation and test method thereof |
| CN112539997B (en) * | 2020-12-15 | 2024-02-20 | 扬州大学 | Basalt fiber reinforced asphalt mortar in-situ tensile fracture test method |
| CN113484107B (en) * | 2021-05-20 | 2023-12-08 | 扬州大学 | Special cutting device of Overlay test piece |
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