CN112268815B - Test method for ice pulling force of concrete dam in cold area - Google Patents
Test method for ice pulling force of concrete dam in cold area Download PDFInfo
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- 238000010998 test method Methods 0.000 title claims abstract description 18
- 238000012360 testing method Methods 0.000 claims abstract description 95
- 238000010008 shearing Methods 0.000 claims abstract description 64
- 239000000203 mixture Substances 0.000 claims abstract description 23
- 238000005520 cutting process Methods 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 claims abstract description 11
- 238000011068 loading method Methods 0.000 claims abstract description 10
- 238000001514 detection method Methods 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 131
- 239000004831 Hot glue Substances 0.000 claims description 12
- 238000000227 grinding Methods 0.000 claims description 9
- 239000010687 lubricating oil Substances 0.000 claims description 7
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 238000007790 scraping Methods 0.000 claims description 6
- 239000003755 preservative agent Substances 0.000 claims description 5
- 230000002335 preservative effect Effects 0.000 claims description 5
- 229910000831 Steel Inorganic materials 0.000 claims description 3
- 238000010009 beating Methods 0.000 claims description 3
- 238000011049 filling Methods 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 239000008213 purified water Substances 0.000 claims description 3
- 238000005507 spraying Methods 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 239000010959 steel Substances 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims 1
- 238000004321 preservation Methods 0.000 description 8
- 238000011144 upstream manufacturing Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 6
- 238000007710 freezing Methods 0.000 description 4
- 230000008014 freezing Effects 0.000 description 4
- 230000001066 destructive effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000008239 natural water Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
- 239000002699 waste material Substances 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
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/38—Diluting, dispersing or mixing samples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
- G01N2001/366—Moulds; Demoulding
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- Life Sciences & Earth Sciences (AREA)
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- Analytical Chemistry (AREA)
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- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a test method for ice pulling force of a concrete dam in a cold area, which comprises the following specific processes: step 1, manufacturing a cube concrete test piece; step 2, cutting the cubic concrete test piece into two equal cuboid concrete test pieces, and reserving the cuboid concrete test pieces with the plastering surfaces; step 3, manufacturing an ice cube-concrete mixture test piece by using the reserved cuboid concrete test piece; step 4, placing the ice block-concrete mixture test piece into a shearing box of a low Wen Zhijian instrument; and 5, setting the temperature of a temperature control system in a low Wen Zhijian instrument, standing, setting the pressure in a vertical pressurizing system in a low Wen Zhijian instrument, setting the shearing speed of a horizontal loading system in a low Wen Zhijian instrument, and starting detection to obtain a shearing stress-strain curve of the contact surface of ice cubes and concrete, thereby obtaining the shearing strength of the contact surface of ice cubes and concrete. The testing method can effectively and intuitively measure the shear strength of the contact surface of the concrete and the ice blocks.
Description
Technical Field
The invention belongs to the technical field of hydraulic building protection, and particularly relates to a test method for ice pulling force of a concrete dam in a cold region.
Background
With the continuous development of water conservancy projects in China, the development of water conservancy projects towards high and cold areas and high altitude areas becomes a necessary trend, such as Tibet, xinjiang, sichuan and other places. When the temperature is lower than 0 ℃, the freezing layer and the upstream dam surface of the dam body are frozen together due to the fact that the water surface of the reservoir is frozen, when the storage flow of the reservoir is smaller than the delivery flow, the water level is lowered to separate the water body from the freezing layer, the freezing layer is subjected to the action of self gravity, and downward destructive force is caused to the upstream dam surface connected with the freezing layer. When the storage flow of the reservoir is larger than the delivery flow, the water level rises, the water body can generate an upward buoyancy force on the frozen layer, an upward destructive force can be generated on the upstream dam surface, and the upstream dam surface is damaged by ice pulling, especially in winter.
In some old water conservancy buildings in severe cold areas of China, as no heat preservation and moisture preservation layers are arranged, ice drawing damage directly acts on concrete, and serious hidden danger is caused to safety and stability of a dam body, some measures are needed to reduce the ice drawing damage. In the newly built hydraulic engineering in the high-cold and high-altitude areas, due to the arrangement of the corresponding heat preservation and moisture preservation layers, ice pulling damage acts on the heat preservation and moisture preservation layers, so that damage to the dam body can be reduced. However, no matter the corresponding measures are taken on the old water conservancy building or the heat preservation and moisture preservation layer is arranged on the new building, the corresponding data indexes are needed to guide the measures, so that the ice pulling damage effect can be effectively reduced, and the resource waste can be avoided.
The prior China patent 201710826801.7 discloses a detection box and a detection method for detecting the ice thrust and ice pulling damage of reservoir icing to a hydraulic building, which can effectively detect the ice thrust of water icing to the hydraulic building in a laboratory and detect whether a test material can resist the ice pulling damage. However, the magnitude of the shear strength of the test material against ice breaking cannot be measured, and in practical situations, the shear strength of the test material against ice breaking is an important measure for measuring the performance of the test material, so a test method capable of detecting the shear strength of the test material against ice breaking is needed.
Disclosure of Invention
The invention aims to provide a test method for the ice pulling force of a concrete dam in a cold region, which can effectively and intuitively measure the shear strength of the contact surface of concrete and ice cubes.
The technical scheme adopted by the invention is that the method for testing the ice pulling force of the concrete dam in the cold area is implemented according to the following steps:
step 1, manufacturing a cube concrete test piece;
step 2, cutting the cubic concrete test piece manufactured in the step 1 into two cuboid concrete test pieces with equal sizes, and reserving the cuboid concrete test pieces with the trowelling surfaces in the cuboid concrete test pieces;
step 3, manufacturing an ice cube-concrete mixture test piece by using the cuboid concrete test piece reserved in the step 2;
step 4, placing the ice cube-concrete mixture test piece manufactured in the step 3 into a shearing box of a low Wen Zhijian instrument;
and 5, setting the temperature of a temperature control system in a low Wen Zhijian instrument, standing, setting a numerical value in a vertical pressurizing system in a low Wen Zhijian instrument, setting the shearing speed of a horizontal loading system in the low Wen Zhijian instrument, starting detection, obtaining a shearing stress strain curve of the contact surface of ice cubes and concrete, and obtaining the shearing strength of the contact surface of ice cubes and concrete through the shearing stress strain curve, thus completing the test.
The invention is also characterized in that:
the step 1 is specifically implemented according to the following steps:
step 1.1, manufacturing a cubic concrete test piece by using a stainless steel die A with the specification of 100mm and concrete, and uniformly coating a layer of lubricating oil on the inner wall of the die A;
step 1.2, after the step 1.1 is completed, taking concrete and uniformly stirring, wherein the particle size of concrete aggregate is not more than 25mm;
step 1.3, placing the concrete obtained in the step 1.2 into a die A treated in the step 1.1, placing the die A with the concrete into a vibrating table for vibrating, keeping the die A without beating until the surface of the concrete is pulped, and then filling a flat steel plate with the thickness of 5mm on the top of the concrete, hammering the concrete by using a rubber hammer to compact the concrete and make the surface flat;
step 1.4, after the concrete processed in the step 1.3 is molded for 24 hours, the die A is disassembled to obtain a cube concrete test piece;
and 1.5, placing the cube concrete test piece obtained in the step 1.4 into a curing box with the temperature of 20 ℃ and the relative humidity of more than 95% for curing for 28 days for later use.
The die A comprises a square bottom plate, wherein one group of two adjacent edges of the bottom plate are vertically provided with first baffle plates, the other group of two adjacent edges of the bottom plate are vertically provided with second baffle plates, baffle plates and bottom plate fixing blocks are arranged on the first baffle plates and the bottom plate and on the second baffle plates and the bottom plate, the adjacent baffle plates and the bottom plate fixing blocks are connected through bolts, baffle plates and baffle plate fixing blocks are arranged at one ends, adjacent to the second baffle plates, of the first baffle plates, and the adjacent baffle plates and the baffle plate fixing blocks are connected through bolts.
The step 2 is specifically implemented according to the following steps:
step 2.1, marking the cube concrete test piece obtained in the step 1 along a half of the height of the cube concrete test piece and drawing cutting lines;
and 2.2, cutting along the cutting line drawn in the step 2.1 by using a cutting machine to obtain two cuboid concrete test pieces with equal sizes, and reserving the cuboid concrete test pieces with the trowelling surfaces.
The step 3 is specifically implemented according to the following steps:
step 3.1, disassembling the die A, uniformly coating a layer of lubricating oil on the inner wall of the die A, and uniformly and flatly attaching a preservative film on the inner wall of the die A;
step 3.2, reassembling the die A, and placing the cuboid concrete test piece with the plastering surface obtained in the step 2.2 into the die A, wherein the cutting surface is placed downwards and is contacted with the bottom plate of the die A, and the plastering surface is positioned in the middle of the die A;
step 3.3, after the hot melt adhesive gun with the hot melt adhesive rod is powered on, preheating for 5 minutes, then treating the joint of the die A with the cuboid concrete test piece with the plastering surface obtained in the step 3.2, and uniformly spraying along the outer part of each contact joint of the die A by using the hot melt adhesive gun until all joints are sprayed;
step 3.4, injecting purified water into the die A treated in the step 3.3 to the water surface and the top level of the die A;
step 3.5, putting the die A treated in the step 3.4 into a refrigerator with the temperature of minus 20 ℃ to be frozen for 10 hours;
step 3.6, taking the die A processed in the step 3.4 out of the refrigerator, scraping ice higher than the top of the die A, fixing the die A on a concrete grinding machine, and grinding the scraped surface to be horizontal to the top of the die A by using the concrete grinding machine to obtain an ice block-concrete mixture test piece;
and 3.7, scraping the hot melt adhesive sprayed at the joint of the die A, disassembling the die A, taking out the ice block-concrete mixture test piece obtained in the step 3.6 from the die, upwards placing the ice block, and placing the concrete in a refrigerator with the temperature of-20 ℃ downwards for later use.
The specific process of the step 4 is as follows: the ice blocks of the ice block-concrete mixture test piece are placed in an upper shearing box of a low Wen Zhijian instrument, and the concrete is placed in a lower shearing box of a low Wen Zhijian instrument, so that the contact interface of the ice blocks and the concrete is kept consistent with the shearing planes of the upper shearing box and the lower shearing box.
Step 5 is specifically implemented according to the following steps:
step 5.1, keeping the temperature set by a temperature control system in the low-temperature direct shear device unchanged, setting different pressures by a vertical pressurizing system, and starting the direct shear device to measure, so that the shear strength of the interface between the ice blocks and the concrete under the action of different ice thrust can be detected when the ice block-concrete mixture test piece is at the same temperature;
step 5.2, the pressure set by the vertical pressurizing system in the low-temperature direct shear device is kept unchanged, the temperature control system is set at different temperatures, the direct shear device is started to measure, and the shearing strength of the interface between the ice blocks and the concrete under the same ice thrust force and the different temperatures can be detected;
and 5.3, keeping the temperature set by a temperature control system in the low-temperature direct shear device unchanged, setting different pressures by a vertical pressurizing system, repeating the step 5.1, keeping the pressure set by the vertical pressurizing system in the low-temperature direct shear device unchanged, setting different temperatures by the temperature control system, and repeating the step 5.2, thereby detecting the shearing strength of the contact surface of ice cubes and concrete under the action of different temperatures and different ice thrusts.
The dimensions of the cubic concrete test pieces in step 1 were 100 x 100mm.
The dimensions of the two cuboids in step 2 were 100 x 50mm.
The invention has the beneficial effects that:
(1) The test method for the ice pulling force of the concrete dam in the cold region has the advantages that the test flow is simple and convenient, the result is easy to realize, the problems that the construction verification of the past test material is required to be carried out on the actual hydraulic engineering, the cost is huge and the time consumption is long are solved, and the laboratory research and application are effectively promoted;
(2) According to the test method for the ice pulling force of the concrete dam in the cold region, the pressure of the vertical pressurizing system can be automatically regulated according to the requirement to simulate the ice pushing force, the temperature of the shearing box is regulated by the temperature control system to reflect the environmental temperature of different projects, the shearing damage condition of the ice pulling action of the upstream dam surface of the concrete dam under the actual condition is effectively simulated, the measured shear stress-strain curve is clear, and the shearing strength of the contact surface of the obtained ice blocks and the concrete is accurate;
(3) According to the test method for the ice pulling force of the concrete dam in the cold region, the concrete dam simulation test piece and the ice layer test piece are manufactured equivalently according to actual working conditions so as to meet the requirements of test instruments, and the test result can accurately and intuitively reflect the stress-strain relation between the concrete dam and the ice layer in the cold region.
Drawings
FIG. 1 is a schematic diagram of the structure of a test piece of an ice-concrete mixture involved in the experimental test method of the present invention;
FIG. 2 is a schematic view of the disassembled structure of the mold A involved in the experimental test method of the present invention;
FIG. 3 is a schematic structural view of a mold A involved in the experimental test method of the present invention;
FIG. 4 is a schematic diagram of the structure of a low Wen Zhijian instrument used in the experimental test method of the present invention.
In the figure, 1, a first baffle, 2, a second baffle, 3, a bottom plate, 4, a baffle and baffle fixing block, 5, a baffle and bottom plate fixing block, 6, ice cubes, 7, concrete, 8, a device fixing system, 9, an upper shearing box, 10, a lower shearing box, 11, a vertical pressurizing system, 12, a horizontal loading system, 13, an automatic data acquisition system and 14, a temperature control system.
Detailed Description
The invention will be described in detail below with reference to the drawings and the detailed description.
The invention discloses a test method for ice pulling force of a concrete dam in a cold region, which is implemented according to the following steps:
step 1, manufacturing 100 x 100mm cubic concrete test pieces;
step 1.1, manufacturing a cubic concrete test piece by using a stainless steel die A with the specification of 100mm and concrete, and uniformly coating a layer of lubricating oil on the inner wall of the die A, wherein the lubricating oil is used for conveniently taking out from the die A after the concrete is finally set;
as shown in fig. 2 and 3, the mold a comprises a square bottom plate 3, wherein a first baffle plate 1 is arranged on one group of two adjacent edges of the bottom plate 3 and is perpendicular to the bottom plate 3, a second baffle plate 2 is arranged on the other group of two adjacent edges of the bottom plate 3 and is perpendicular to the bottom plate 3, baffle plate and bottom plate fixing blocks 5 are arranged on the first baffle plate 1, the bottom plate 3, the second baffle plate 2 and the bottom plate 3, the adjacent baffle plates are connected with the bottom plate fixing blocks 5 through bolts, baffle plate and baffle plate fixing blocks 4 are arranged at one ends of the first baffle plate 1, the adjacent baffle plate and the second baffle plate 2, and the adjacent baffle plates are connected with the baffle plate fixing blocks 4 through bolts;
step 1.2, after the step 1.1 is completed, taking concrete and uniformly stirring, wherein the particle size of concrete aggregate is not more than 25mm;
step 1.3, placing the concrete obtained in the step 1.2 into a die A treated in the step 1.1, placing the die A with the concrete into a vibrating table for vibrating, keeping the die A without beating until the surface of the concrete is pulped, and then filling a flat steel plate with the thickness of 5mm on the top of the concrete, hammering the concrete by using a rubber hammer to compact the concrete and make the surface flat;
step 1.4, after the concrete processed in the step 1.3 is molded for 24 hours, the die A is disassembled to obtain a cube concrete test piece;
step 1.5, placing the cubic concrete test piece obtained in the step 1.4 into a curing box with the temperature of 20 ℃ and the relative humidity of more than 95% for curing for 28 days for later use;
step 2, cutting the cubic concrete test piece manufactured in the step 1 into two 100 x 50mm cuboid concrete test pieces with the same size, and reserving the cuboid concrete test piece with a plastering surface;
step 2.1, marking the cubic concrete test piece obtained in the step 1 along the position of 50mm in height and drawing cutting lines;
step 2.2, cutting along the cutting line drawn in the step 2.1 by using a cutting machine to obtain two cuboid concrete test pieces with the same size of 100 x 50mm, and reserving the cuboid concrete test pieces with a plastering surface;
step 3, manufacturing an ice cube-concrete mixture test piece shown in fig. 1 by using the cuboid concrete test piece reserved in the step 2;
step 3.1, disassembling the die A, uniformly coating a layer of lubricating oil on the inner wall of the die A, uniformly and flatly attaching a preservative film on the inner wall (a first baffle, a second baffle and a bottom plate) of the die A, ensuring that the preservative film is flatly and uniformly, and mainly preventing ice cubes from being frozen together with the die A to cause difficult die disassembly; the method comprises the steps of carrying out a first treatment on the surface of the
Step 3.2, reassembling the die A, and putting the cuboid concrete test piece with the plastering surface obtained in the step 2 into the die A, wherein the cutting surface is placed downwards and is contacted with the bottom plate of the die A, and the plastering surface is positioned in the middle of the die A and is used for simulating the actual situation that the upstream dam surface of the concrete is vertical and contacted with water, so that the integrity of the preservative film is ensured and the scratch is avoided when the concrete is placed;
step 3.3, after the hot melt adhesive gun with the hot melt adhesive rod is powered on, preheating for 5 minutes, then treating the joint of the die A with the cuboid concrete test piece with the plastering surface obtained in the step 3.2, and uniformly spraying the hot melt adhesive gun along the outer part of each contact joint of the die A until all joints are sprayed, so that good sealing performance of the die A is ensured, and no water leakage is caused;
step 3.4, injecting purified water into the die A treated in the step 3.3 to the water surface and the top level of the die A;
step 3.5, putting the die A treated in the step 3.4 into a refrigerator with the temperature of minus 20 ℃ to be frozen for 10 hours;
step 3.6, taking the die A processed in the step 3.4 out of the refrigerator, scraping off ice (redundant ice generated due to expansion) higher than the top of the die A, fixing the die A on a concrete grinding machine, and grinding the scraped surface to be horizontal to the top of the die A by using the concrete grinding machine to obtain an ice block-concrete mixture test piece;
step 3.7, scraping the hot melt adhesive sprayed at the joint of the die A, disassembling the die A, taking out the ice block-concrete mixture test piece obtained in the step 3.6 from the die, upwards placing the ice block, and downwards placing the concrete in a refrigerator with the temperature of-20 ℃ for later use;
step 4, placing the ice cube-concrete mixture test piece manufactured in the step 3 into a shearing box of a low Wen Zhijian instrument;
as shown in fig. 4, the low Wen Zhijian instrument is an STY-1000 low Wen Zhijian instrument manufactured by the Sichuan Xiang instruments, inc., and comprises an upper shearing box 9 and a lower shearing box 10 which are arranged up and down, wherein the heights of the upper shearing box 9 and the lower shearing box 10 are 50mm, the interface between the upper shearing box 9 and the lower shearing box 10 is a shearing plane, the bottom of the lower shearing box 10 is provided with a device fixing system 8, the outer parts of the upper shearing box 9 and the lower shearing box 10 are provided with a temperature control system 14, the temperature during testing can be set, the temperature range of the temperature control system 14 is 0-20 ℃, the top of the upper shearing box 9 is provided with a vertical pressurizing system 11 for simulating ice pushing force generated during icing, the pressure can be adjusted by itself, one side surface of the upper shearing box 9 is provided with a horizontal loading system 12, the horizontal loading system 12 is connected with an automatic data acquisition system 13, and the shearing stress-strain curve of the contact interface between ice blocks and concrete can be obtained directly during measurement;
placing the ice cubes 6 of the ice cube-concrete mixture test piece into an upper shearing box 9 of the low-temperature direct shear apparatus, and placing the concrete 7 into a lower shearing box 10 of the low-temperature direct shear apparatus, so that the contact interface of the ice cubes 6 and the concrete 7 is consistent with the shearing planes of the upper shearing box 9 and the lower shearing box 10;
step 5, setting the temperature of the temperature control system 14 in the low Wen Zhijian instrument and standing for 10min, setting the pressure in the vertical pressurizing system 11 in the low Wen Zhijian instrument, setting the shearing speed of the horizontal loading system 12 in the low Wen Zhijian instrument to be 0.8mm/min, starting detection, obtaining a shearing stress-strain curve of the contact surface of ice cubes and concrete, and obtaining the shearing strength of the contact surface of ice cubes and concrete through the shearing stress-strain curve;
step 5.1, keeping the temperature set by the temperature control system 14 in the low-temperature direct shear device unchanged, setting different pressures by the vertical pressurizing system 11, and starting the direct shear device to measure, so that the shear strength of the interface between the ice blocks and the concrete under the action of different ice thrust can be detected when the ice block-concrete mixture test piece is at the same temperature;
step 5.2, the pressure set by the vertical pressurizing system 11 in the low-temperature direct shear apparatus is kept unchanged, the temperature control system 14 is set at different temperatures, and the direct shear apparatus is started to measure, so that the shearing strength of the interface between the ice blocks and the concrete under the action of the same ice thrust can be detected;
and 5.3, keeping the temperature set by the temperature control system 14 in the low-temperature direct shear device unchanged, setting different pressures by the vertical pressurizing system 11, repeating the step 5.1, keeping the pressure set by the vertical pressurizing system 11 in the low-temperature direct shear device unchanged, setting different temperatures by the temperature control system 14, and repeating the step 5.2, thereby detecting the shearing strength of the contact surface of ice cubes and concrete under the action of different temperatures and different ice thrusts.
The invention provides a test method for the ice pulling force of a concrete dam in a cold region, which can effectively and intuitively measure the shear strength of the contact surface of concrete and ice cubes and has the following principle:
in practical situations, the contact interface between the frozen layer and the upstream dam face of the concrete is a weak face of the integral structure, so that concrete is easy to damage and destroy on the contact face, and the shear strength of the contact face of ice cubes and the concrete is an important index for measuring the structural stability of the ice cubes and the concrete, so that the shear strength of the contact face of the ice cubes and the concrete is necessary to be measured. The method comprises the steps of simulating the situation that a natural water body and a concrete dam surface are frozen together in a laboratory, preparing an ice cube-concrete mixture test piece, and then performing a direct shear test on the ice cube-concrete mixture test piece by using a low Wen Zhijian instrument which is provided with an upper shear box, a lower shear box, a vertical pressurizing system, a horizontal loading system and a temperature control system, wherein the temperature control system can adjust different temperatures and simulate different temperatures under practical conditions; the vertical pressurizing system can adjust different pressures and simulate different ice pushing forces of ice cubes on the concrete dam surface under actual conditions; the horizontal loading system is used for simulating the action of self gravity of ice cubes and the action of water body on the buoyancy of the ice cubes under the actual condition. In the shearing process, the ice blocks and the concrete are assumed to be rigid bodies, the ice blocks and the concrete are not deformed, displacement only occurs at the contact surface of the ice blocks and the concrete, the horizontal loading system is connected with the data automatic acquisition system, a shearing stress-strain curve can be automatically processed and drawn, and finally the shearing strength of the contact surface of the ice blocks and the concrete can be obtained.
The invention provides a test method for the ice pulling force of a concrete dam in a cold region, which can effectively and directly measure the shear strength of the contact surface of concrete and ice cubes, is simple to operate and easy to realize, can automatically adjust the pressure of a vertical pressurizing system according to requirements to simulate the ice pushing force, can effectively simulate the shearing damage condition of the ice pulling action of the upstream dam surface of the concrete dam under actual conditions by adjusting the temperature of a temperature control system, has a clear measured shear stress-strain curve, has accurate shear strength of the contact surface of the ice cubes and the concrete, and can effectively avoid the condition that the effect of an ice pulling resistant device is not ideal or resources are wasted due to no corresponding data index guidance in the past.
Claims (7)
1. The test method for the ice pulling force of the concrete dam in the cold area is characterized by comprising the following steps of:
step 1, manufacturing a cube concrete test piece;
the step 1 is specifically implemented according to the following steps:
step 1.1, manufacturing a cubic concrete test piece by using a stainless steel die A with the specification of 100mm and concrete, and uniformly coating a layer of lubricating oil on the inner wall of the die A;
step 1.2, after the step 1.1 is completed, taking concrete and uniformly stirring, wherein the particle size of concrete aggregate is not more than 25mm;
step 1.3, placing the concrete obtained in the step 1.2 into a die A treated in the step 1.1, placing the die A with the concrete into a vibrating table for vibrating, keeping the die A without beating until the surface of the concrete is pulped, and then filling a flat steel plate with the thickness of 5mm on the top of the concrete, hammering the concrete by using a rubber hammer to compact the concrete and make the surface flat;
step 1.4, after the concrete processed in the step 1.3 is molded into 24h, the die A is disassembled to obtain a cubic concrete test piece;
step 1.5, placing the cubic concrete test piece obtained in the step 1.4 into a curing box with the temperature of 20 ℃ and the relative humidity of more than 95% for curing for 28 days for later use;
step 2, cutting the cubic concrete test piece manufactured in the step 1 into two cuboid concrete test pieces with equal sizes, and reserving the cuboid concrete test pieces with the trowelling surfaces in the cuboid concrete test pieces;
step 3, manufacturing an ice cube-concrete mixture test piece by using the cuboid concrete test piece reserved in the step 2;
the step 3 is specifically implemented according to the following steps:
step 3.1, disassembling the die A, uniformly coating a layer of lubricating oil on the inner wall of the die A, and uniformly and flatly attaching a preservative film on the inner wall of the die A;
step 3.2, reassembling the die A, and placing the cuboid concrete test piece with the plastering surface obtained in the step 2 into the die A, wherein the cutting surface is placed downwards and is contacted with the bottom plate of the die A, and the plastering surface is positioned in the middle of the die A;
step 3.3, after the hot melt adhesive gun with the hot melt adhesive rod is powered on, preheating for 5 minutes, then treating the joint of the die A with the cuboid concrete test piece with the plastering surface obtained in the step 3.2, and uniformly spraying along the outer part of each contact joint of the die A by using the hot melt adhesive gun until all joints are sprayed;
step 3.4, injecting purified water into the die A treated in the step 3.3 to the water surface and the top level of the die A;
step 3.5, putting the die A treated in the step 3.4 into a refrigerator with the temperature of minus 20 ℃ to be frozen for 10 hours;
step 3.6, taking the die A processed in the step 3.4 out of the refrigerator, scraping ice higher than the top of the die A, fixing the die A on a concrete grinding machine, and grinding the scraped surface to be horizontal to the top of the die A by using the concrete grinding machine to obtain an ice block-concrete mixture test piece;
step 3.7, scraping the hot melt adhesive sprayed at the joint of the die A, disassembling the die A, taking out the ice block-concrete mixture test piece obtained in the step 3.6 from the die, upwards placing the ice block, and downwards placing the concrete in a refrigerator with the temperature of-20 ℃ for later use;
step 4, placing the ice cube-concrete mixture test piece manufactured in the step 3 into a shearing box of a low Wen Zhijian instrument;
setting the temperature of a temperature control system (14) in a low Wen Zhijian instrument, standing, setting the pressure in a vertical pressurizing system (11) in a low Wen Zhijian instrument, setting the shearing speed of a horizontal loading system (12) in a low Wen Zhijian instrument, starting detection, obtaining a shearing stress-strain curve of the contact surface of ice cubes and concrete, and obtaining the shearing strength of the contact surface of ice cubes and concrete through the shearing stress-strain curve, thus completing the test;
the step 5 is specifically implemented according to the following steps:
step 5.1, keeping the temperature set by a temperature control system (14) in the low-temperature direct shear device unchanged, setting different pressures by a vertical pressurizing system (11), and starting the direct shear device to measure, so that the shearing strength of the interface between the ice and the concrete under the action of different ice thrusts can be detected when the ice-concrete mixture test piece is at the same temperature;
step 5.2, the pressure set by the vertical pressurizing system (11) in the low-temperature direct shear apparatus is kept unchanged, the temperature control system (14) is set at different temperatures, and the direct shear apparatus is started to measure, so that the shearing strength of the interface between the ice and the concrete under the same ice thrust and different temperatures can be detected;
and 5.3, keeping the temperature set by a temperature control system (14) in the low-temperature direct shear device unchanged, setting different pressures by a vertical pressurizing system (11), repeating the step 5.1, keeping the pressure set by the vertical pressurizing system (11) in the low-temperature direct shear device unchanged, setting different temperatures by the temperature control system (14), and repeating the step 5.2, thereby detecting the shearing strength of the contact surface of ice cubes and concrete under the action of different ice thrusts at different temperatures.
2. The test method for the ice pulling force of the concrete dam in the cold area according to claim 1, wherein the die A comprises a square bottom plate (3), a first baffle (1) is arranged on one group of two adjacent edges of the bottom plate (3) and perpendicular to the bottom plate (3), a second baffle (2) is arranged on the other group of two adjacent edges of the bottom plate (3) and perpendicular to the bottom plate (3), baffle and bottom plate fixing blocks (5) are arranged on the first baffle (1) and the bottom plate (3) and on the second baffle (2) and the bottom plate (3), adjacent baffle and bottom plate fixing blocks (5) are connected through bolts, baffle and baffle fixing blocks (4) are arranged at one ends, adjacent to the first baffle (1) and the second baffle (2), and the adjacent baffle and baffle fixing blocks (4) are connected through bolts.
3. The method for testing the ice pulling force of the concrete dam in the cold area according to claim 1, wherein the step 2 is specifically implemented according to the following steps:
step 2.1, marking the cube concrete test piece obtained in the step 1 along a half of the height of the cube concrete test piece and drawing cutting lines;
and 2.2, cutting along the cutting line drawn in the step 2.1 by using a cutting machine to obtain two cuboid concrete test pieces with equal sizes, and reserving the cuboid concrete test pieces with the trowelling surfaces.
4. The method for testing the ice pulling force of the concrete dam in the cold area according to claim 1, wherein the specific process of the step 4 is as follows: the ice cubes (6) of the ice cube-concrete mixture test piece are placed in an upper shearing box (9) of a low Wen Zhijian instrument, and the concrete is placed in a lower shearing box (10) of a low Wen Zhijian instrument, so that the contact interface of the ice cubes (6) and the concrete (7) is kept consistent with the shearing planes of the upper shearing box (9) and the lower shearing box (10).
5. The method for testing ice pulling force of concrete dams in cold regions according to claim 1, wherein the dimensions of the cubic concrete test pieces in step 1 are 100 x 100mm.
6. The method for testing ice pulling force of concrete dams in cold regions according to claim 1, wherein the dimensions of the two rectangular solids in step 2 are 100×100×50mm.
7. The method for testing ice pulling force of concrete dams in cold regions according to claim 1, wherein in step 5, the standing time is 10min, and the shearing speed is 0.8mm/min.
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| CN114397241B (en) * | 2022-01-11 | 2024-01-09 | 西安理工大学 | Method for testing adhesion performance between asphalt and acidic aggregate by considering water flow effect |
| CN114544487B (en) * | 2022-01-11 | 2023-10-27 | 西安理工大学 | Method for testing adhesion performance of asphalt and aggregate interface transition area in core wall dam |
| CN114397198A (en) * | 2022-01-14 | 2022-04-26 | 南通理工学院 | Novel test method for Z-shaped precast crack concrete shear strength test specimen |
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