CN114894606B - Device and method for testing creep property of geosynthetic material - Google Patents
Device and method for testing creep property of geosynthetic material Download PDFInfo
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- 238000012360 testing method Methods 0.000 title claims abstract description 179
- 239000000463 material Substances 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 12
- 239000002689 soil Substances 0.000 claims abstract description 49
- 230000007246 mechanism Effects 0.000 claims abstract description 15
- 238000010998 test method Methods 0.000 claims abstract description 5
- 238000006073 displacement reaction Methods 0.000 claims description 16
- 239000012780 transparent material Substances 0.000 claims description 4
- 238000004088 simulation Methods 0.000 abstract description 6
- 230000007774 longterm Effects 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
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- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000036316 preload Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 239000005061 synthetic rubber Substances 0.000 description 1
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- G—PHYSICS
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- 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
- G01N3/02—Details
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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
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01N2203/0001—Type of application of the stress
- G01N2203/0003—Steady
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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
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0042—Pneumatic or hydraulic means
- G01N2203/0048—Hydraulic means
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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
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0071—Creep
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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
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
- G01N2203/0222—Temperature
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Abstract
The invention provides a device for testing creep property of a geosynthetic material, which comprises: the device comprises a shell, a test box, a vertical loading device, a horizontal loading device, a clamp and a control system; the test box comprises a pair of adjustable side walls, and a height-adjustable test port is arranged on each adjustable side wall; the horizontal loading device is installed on the test bed through the support frame, a height adjusting mechanism is arranged between the horizontal loading device and the support frame and used for adjusting the height of the horizontal loading device, so that the heights of the horizontal loading device and the test port are kept consistent. The invention also provides a test method of the test device based on the geosynthetic material creep property, and the method realizes the simulation test of the geosynthetic material creep property under different soil depth conditions by adjusting the positions of the test port and the horizontal loading device, so as to obtain more accurate and reliable creep property data, and has important guiding significance on the structural safety of reinforced soil.
Description
Technical Field
The invention belongs to the technical field of geosynthetic material performance tests, and particularly relates to a device for testing the creep performance of a geosynthetic material, and a method for testing the creep performance of the geosynthetic material.
Background
The earthwork composite material is a civil engineering material, which is produced by using artificially synthesized polymer (such as plastics, chemical fiber and synthetic rubber) as raw material to prepare different types of products, and placing the products in the interior or on the surface of soil body to play the role of reinforcing or protecting the soil body. Creep of geosynthetic materials is a phenomenon in which strain increases over time, while maintaining the stress unchanged. When the geosynthetic material is placed in the soil, it is subjected to long-term loading of the soil, a stretched state is formed, and long-term accumulation of the above phenomenon affects the stability of the soil. Creep of geosynthetic materials can result in changes in internal stresses of the reinforced earth structure, thereby affecting the long-term stability of the reinforced earth structure, causing instability or excessive deformation of the reinforced earth. Thus, predicting long-term creep of geosynthetics is important to the safety of reinforced earth structures.
At present, researchers have developed test devices for creep properties of geosynthetics to achieve simulation tests for creep properties of the geotechnical materials, however, such devices have problems including: (1) The clamps arranged up and down are affected by gravity, so that the measurement result is inaccurate; (2) The loading of the weight cannot meet the requirement of uniform stress of the material; (3) The equipment test is long in time consumption, large in workload, difficult to control in displacement speed adjustment and the like. The existence of the problems causes larger deviation between the creep performance test result and the actual situation, and accurate and reliable creep performance test data cannot be obtained.
The China patent with the application number 201710639007.1 discloses a test platform for testing creep performance of a geosynthetic material, which is characterized in that soil is filled in a test box, and then the geotechnical material to be tested is placed in the soil, so that the creep performance under the condition of soil restraint/lateral limitation is tested. The device enables the test result to be more close to the real situation through simulating the real environment, and improves the test accuracy.
However, the device is only tested on the premise of adopting a test box with a fixed form and filling a fixed amount of soil, can only obtain the creep performance of the geotechnical material under a certain fixed condition in a limited way, and has no wide applicability. In addition, more researches show that the geosynthetic material has different reinforcement effects under different depth conditions in the soil, and different creep phenomena are generated due to different forces suffered by the geosynthetic material, so that the measurement of the creep performance of the geosynthetic material under the soil conditions with different depths has important significance.
Based on the above, how to improve the conventional geosynthetic material creep performance testing device, so that the device can test the creep performance of the geosynthetic material under different soil depth conditions to obtain more accurate and reliable creep performance data, has important guiding significance for structural safety assessment and stability analysis of reinforced soil, and is a technical problem to be solved.
Disclosure of Invention
One of the purposes of the invention is to provide a device capable of testing the creep performance of the geosynthetic material under different soil depth conditions.
The second purpose of the invention is to provide a test method for simulating the creep performance of the geosynthetic material under different soil depth conditions.
One of the achievement purposes of the invention adopts the technical proposal that: there is provided a geosynthetic material creep performance testing apparatus comprising: the device comprises a shell, a test box, a vertical loading device, a horizontal loading device, a clamp, a temperature control assembly and a control system;
The test box is arranged on a test bed at the bottom of the shell; the test box comprises a pair of fixed side walls and a pair of adjustable side walls, and a test port with adjustable height is arranged on the adjustable side walls;
the vertical loading device is positioned above the test box, and the fixed end of the vertical loading device is arranged on a transverse frame at the top of the shell; the movable end of the vertical loading device is used for applying vertical pressure to soil in the test box;
the horizontal loading device is positioned at two sides of a pair of adjustable side walls of the test box and is arranged on the test bed through a supporting frame; the movable end of the horizontal loading device is connected with a clamp, and the clamp is provided with a clamping jaw for clamping a geosynthetic material sample;
A height adjusting mechanism is arranged between the horizontal loading device and the supporting frame; the height adjusting mechanism is used for adjusting the height of the horizontal loading device so that the height of the horizontal loading device is consistent with the height of the test port;
The control system comprises a power supply, a displacement sensor, a tension sensor, a temperature regulator, a display screen and a control panel.
On the basis of the technical scheme, the adjustable side wall of the test box comprises an adjusting frame, a top fixing plate, a bottom fixing plate and a plurality of sliding plates;
Slide rails for the sliding plates to move are arranged on two sides of the adjusting frame; and the test ports are formed between adjacent sliding plates, between the sliding plates and the top fixed plate or between the sliding plates and the bottom fixed plate by moving the sliding plates.
On the basis of the technical scheme, the test port is positioned at 1/4-3/4 of the height of the test box.
On the basis of the technical scheme, the fixed side wall of the test box is made of high-strength transparent materials, and a scale is arranged at the edge of the fixed side wall adjacent to the adjustable side wall.
On the basis of the technical scheme, the vertical loading device is a hydraulic servo loading device and comprises a loading plate positioned at the bottom of the movable end, and the loading plate is used for applying vertical pressure to soil in the test box.
On the basis of the technical scheme, the horizontal loading device comprises a horizontal hydraulic servo device, the horizontal loading device is used for providing pre-loading tension for the geosynthetic material sample, and the tension rate provided by the horizontal loading device is 0.1-50 mm/min.
On the basis of the technical scheme, the height adjusting mechanism is an electric servo telescopic rod, the fixed end of the height adjusting mechanism is arranged on the top plate of the supporting frame, and the movable end of the height adjusting mechanism is connected with the horizontal loading device.
On the basis of the technical scheme, the temperature control assembly comprises a temperature control box covered outside the test box, and the temperature regulation range in the temperature control box is-20-99 ℃.
The second technical scheme adopted for realizing the purpose of the invention is as follows: the invention provides a method for testing the creep property of a geosynthetic material, which comprises the following steps:
S1, adjusting the positions of the test ports on a pair of adjustable side walls and the height of a horizontal loading device to enable the positions of the test ports and the height of the horizontal loading device to be on the same horizontal line;
s2, paving a first layer of soil to be flush with the horizontal loading device;
S3, transversely placing the geosynthetic material sample in a test box filled with soil, and clamping two ends of the geosynthetic material sample by using clamping jaws of a clamp;
s4, laying a second layer of soil to be flush with the top of the fixed side wall;
S5, adjusting the temperature control assembly to set a test temperature, starting the vertical loading device, and applying preset pressure to soil in the test box;
And S6, data acquisition is carried out at intervals of a certain time until the time required by the test is reached, and the test is ended.
On the basis of the above technical solution, before the step S5, the method further includes the following steps: and applying a preloading pulling force to the geosynthetic material sample by using a horizontal loading device to enable the geosynthetic material sample to generate 1% tensile strength preloading, recording a pulling force value by using a pulling force sensor, and recording corresponding displacement by using a displacement sensor.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention provides a test device for creep property of geosynthetic materials, which comprises a test box, wherein the test box comprises a pair of fixed side walls and a pair of adjustable side walls, and the adjustable side walls are provided with height-adjustable test ports. The horizontal loading devices arranged on two sides of the pair of adjustable side walls are connected with the supporting frame through the height adjusting mechanisms, the vertical heights of the horizontal loading devices can be adjusted through controlling the height adjusting mechanisms, the heights of the horizontal loading devices and the test ports are kept consistent, and then the geosynthetic material samples are placed according to the positions of the test ports and filled with different amounts of soil, so that the creep performance of the geosynthetic material is tested under the condition of different soil depths.
(2) According to the test method for the creep property of the geosynthetic material, provided by the invention, the test box with the height-adjustable test port is utilized, and the adjustment of the placement position of the geosynthetic material in the test box is realized by matching with the height-adjustable horizontal loading device, so that the tensile creep or tensile creep rupture of the geosynthetic material under different soil depths is more truly simulated, and an effective way is provided for further exploring the creep property of the geosynthetic material. In addition, by comparing the creep performance data of the geosynthetic materials under a plurality of groups of different depth conditions, the most suitable soil depth condition of the geosynthetic materials can be found, and the method has important guiding significance for soil reinforcement operation in actual engineering.
Drawings
FIG. 1 is a schematic diagram of the overall structure of a geosynthetic material creep performance testing device according to an embodiment of the invention;
FIG. 2 is a schematic structural diagram of a test box according to an embodiment of the present invention;
FIG. 3 is a top view of a test chamber provided in an embodiment of the present invention;
FIG. 4 is a schematic structural view of a fixed sidewall according to an embodiment of the present invention;
Fig. 5 is a schematic structural view of a clamping jaw of a clamp according to an embodiment of the present invention;
fig. 6 is a side view of a support stand according to an embodiment of the present invention.
Wherein, 1-shell; 11-a test stand; 12-supporting frames; 2-a test box; 21-securing the side walls; 212-scale; 22-adjustable side walls; 221-an adjusting frame; 222-top fixing plate; 223-bottom securing plate; 224-sliding plate; 23-test port; 3-a vertical loading device; 31-loading plate; 4-horizontal loading means; 41-a height adjustment mechanism; 5-clamping; 51-clamping jaw; 6-a temperature control component; 61-temperature control box.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The invention will be further illustrated, but is not limited, by the following examples.
Example 1
Referring to fig. 1, the embodiment provides a test device for creep performance of a geosynthetic material, which includes: the device comprises a shell 1, a test box 2, a vertical loading device 3, a horizontal loading device 4, a clamp 5, a temperature control assembly 6 and a control system;
The test box 2 is arranged on the test bed 11 at the bottom of the shell 1, the test box 2 comprises a pair of fixed side walls 21 and a pair of adjustable side walls 22, and a test port 23 with adjustable height is arranged on the adjustable side walls 22; the vertical loading device 3 is positioned above the test box 2, the fixed end of the vertical loading device is arranged on a transverse frame at the top of the shell 1, and the movable end of the vertical loading device is used for applying vertical pressure to soil in the test box 2; the horizontal loading device 4 is arranged on two sides of a pair of adjustable side walls 22 of the test box 2 and is arranged on the test stand 11 through a support frame 12; the movable end of the horizontal loading device 4 is connected with a clamp 5, and the clamp 5 is provided with a clamping jaw 51 for clamping a geosynthetic material sample; a height adjusting mechanism 41 is also arranged between the horizontal loading device 4 and the supporting frame 12; the height adjusting mechanism 41 is used for adjusting the height of the horizontal loading device 4 so that the height of the horizontal loading device 4 is consistent with the height of the test port 23.
The control system comprises a power supply, a displacement sensor, a tension sensor, a temperature regulator, a display screen and a control panel. In the present embodiment, the displacement sensor and the tension sensor are respectively provided on both sides of the position of the horizontal loading device 4 near the support frame 12. The tension sensor is used for measuring the tension loaded on the geosynthetic material, and the displacement sensor is used for measuring the elongation of the geosynthetic material. The temperature regulator is used for regulating the test temperature of the temperature control assembly 6, and the control panel is used for regulating horizontal and vertical pulling force and pressure. The signal output end of the industrial personal computer of the control system is connected with a display screen, and the display screen displays the vertical loading pressure, the horizontal loading tension and the elongation of the geosynthetic material.
According to the test device for the creep performance of the geosynthetic material, provided by the embodiment, the heights of the test port 23 and the horizontal loading device 4 are adjustable, a tester can adjust the position of the opening of the test port 23 and the height position of the horizontal loading device 4 according to the test requirement of the geosynthetic material sample to determine the placement position of the geosynthetic material sample, and fill soil below and above the geosynthetic material sample, so that the purpose of placing the geosynthetic material in soil environments with different heights of the test box and performing simulation test is achieved. The testing device can simulate creep dynamics of the geosynthetic material under different soil depths, and compared with the past testing device, the testing result of the device is closer to the actual engineering situation.
Referring to fig. 2 and 3, the test box 2 of the present embodiment has a rectangular parallelepiped structure, with an open top and a closed bottom, and side walls are provided around the test box, and the side walls adjacent to the horizontal loading device 4 are adjustable side walls 22. The adjustable side wall 22 comprises an adjusting frame 221, a top fixing plate 222, a bottom fixing plate 223 and a plurality of sliding plates 224; slide rails for the sliding plate 224 to move are provided on both sides of the adjusting frame 221; by moving the sliding plates 224, the test port 23 is formed between the adjacent sliding plates 224, between the sliding plates 224 and the top fixing plate 222, or between the sliding plates 224 and the bottom fixing plate 223.
In the present embodiment, the distance between the top fixing plate 222 and the bottom fixing plate 223 is the adjustable range of the opening of the test port 23. Preferably, the test port 23 is located at 1/4-3/4 of the height of the test box 2, and the height position and opening size of the test port 23 can be adjusted by adjusting the position of the sliding plate 224 (including moving the upper sliding plate 224 downward, the lower sliding plate 224 upward, or both the upper and lower sliding plates 224). Further, the adjusting frame 221 is provided with sliding rails, each sliding plate 224 is slidably connected with the sliding rails through a sliding block, and each sliding block is provided with a locking button for locking the position of the sliding plate 224.
Specifically, the number and size of the sliding plates 224 can be flexibly set according to actual test requirements. In this embodiment, the top fixing plate 222, the bottom fixing plate 223 and the sliding plate 224 have the same size, two sliding rails are respectively disposed on two sides of the adjusting frame 221, and one sliding plate 224 (i.e. four sliding plates in total) is disposed on each sliding rail. The pair of sliding plates 224 located on the inner side are mainly used for adjusting the height position and the opening size of the test port 23, the pair of sliding plates 224 located on the outer side play an auxiliary supporting role, the auxiliary supporting role is moved to the outer side of the joint of the fixed plate and the sliding plates 224, the reinforcing role can be played on the test box 2, and then the overall stability of the test box 2 in the test process is maintained.
Referring to fig. 4, the fixed side wall 21 of the test chamber 2 is made of a high-strength transparent material, and graduations 212 are provided on the edge of the fixed side wall 21 adjacent to the adjustable side wall 22. In this embodiment, the fixed side wall 21 is made of tempered glass, so that a tester can observe the test from outside the housing 1. The edge of the fixed side wall 21 is provided with a scale 212, the scale 212 is provided with scales for marking the position of the test port 23, the height of the sliding plate 224 is convenient to adjust, the set position of the test port 23 is controlled, and the accuracy of the simulation test is improved.
In this embodiment, the height of the test box is 400mm, the lengths of the top fixing plate 222, the bottom fixing plate 223 and the four sliding plates 224 are 100mm, the thickness is 10mm, and the scale range of the scale 212 is 1/4 to 3/4 of the height of the test box. In some other embodiments, the above dimensions may also be adjusted according to the soil depth tested and the specifications of the geosynthetic material.
Further, the vertical loading device 3 adopts a hydraulic servo loading device, and comprises a loading plate 31 positioned at the bottom of the movable end, wherein the loading plate 31 is used for extending into the test box 2 to apply vertical pressure to soil in the test box 2 and compacting the soil in the test box 2. The size of the loading plate 31 is slightly smaller than the size of the top opening of the test box 2 to ensure uniform loading of the load.
The horizontal loading device 4 comprises a horizontal hydraulic servo device, the horizontal loading device 4 is used for providing a pre-loading pulling force for the geosynthetic material sample, and the pulling force rate provided by the horizontal loading device 4 is 0.1-50 mm/min.
Referring to fig. 5, the clamp 5 includes a pair of clamping jaws 51, the clamping jaws 51 are provided with an upper clamping plate and a lower clamping plate, and the contact surfaces of the upper clamping plate and the lower clamping plate are engaged in a saw-tooth shape, so as to ensure stable clamping of the sample. The clamping jaw 51 is also provided with an adjusting member for adjusting the spacing between the upper and lower clamping plates to accommodate testing requirements for samples of different thickness.
Referring to fig. 6, a supporting frame 12 is fixed on a test stand 11, a height adjusting mechanism 41 is an electric servo telescopic rod, a fixed end of the electric servo telescopic rod is fixedly connected with the top of the supporting frame 12, and a movable end of the electric servo telescopic rod is connected with a horizontal loading device 4. The height position of the horizontal loading device 4 is adjusted by controlling the extending length of the movable end of the electric servo telescopic rod, so that the height of the clamp 5 connected with the horizontal loading device 4 is consistent with the height of the sample in the test port 23 (basically on the same horizontal line).
In this embodiment, the testing device is further provided with a temperature control assembly 6, the temperature control assembly 6 includes a temperature control box 61 covered outside the testing box, and the temperature adjustment range in the temperature control box 61 is-20-90 ℃. By adjusting the temperature in the temperature control box 61, the soil and the geosynthetic material in the test box 2 are subjected to simulation tests of creep properties under different temperature conditions, so that the test conditions are more similar to the actual application scenes. Preferably, the temperature control box 61 is made of transparent materials, so that the internal test condition of the temperature control box can be conveniently observed.
Furthermore, in order to ensure the accuracy and timeliness of timing, the control system of the test device of the embodiment further comprises a timing device, and the timing device is connected with the control system, and can continuously record or record the elongation of the sample at specified time intervals and the time when the sample breaks, so that special recording is not needed, and the workload of test operators is reduced. The testing device of the embodiment can be further provided with a power failure protection device and an emergency stop device so as to cope with emergency situations in the testing process and ensure the testing safety.
Example 2
The present embodiment provides a test method based on the test device for creep property of geosynthetic material in embodiment 1, comprising the following steps:
S1, adjusting the positions of the test ports 23 on the pair of adjustable side walls 22 and the height of the horizontal loading device 4 to enable the positions of the test ports and the height of the horizontal loading device to be on the same horizontal line;
s2, paving a first layer of soil to be flush with the horizontal loading device 4;
s3, transversely placing the geosynthetic material sample in a test box 2 filled with soil, and clamping two ends of the geosynthetic material sample by using clamping jaws 51 of a clamp 5;
s4, laying a second layer of soil to be flush with the top of the fixed side wall 21;
s5, adjusting the temperature control assembly 6 to set a test temperature, starting the vertical loading device 3, and applying preset pressure to soil in the test box 2;
And S6, data acquisition is carried out at intervals of a certain time until the time required by the test is reached, and the test is ended.
Further, before the step S5, the method further includes the following steps: the horizontal loading device 4 is used for applying a pre-loading tension to the geosynthetic material sample so as to generate 1% tensile strength pre-loading, a tension value is recorded through a tension sensor, and corresponding displacement is recorded through a displacement sensor.
In the operation, the horizontal loading device 4 is used for preloading, so that the geosynthetic material generates preloading with the tensile strength of about 1%, the tension value is recorded through the tension sensor, and the corresponding displacement is recorded through the displacement sensor, so that the test is started, the good contact of each part of the test piece can be ensured, the relationship between the load and the deformation tends to be stable, the accuracy of the test result is improved, and the smooth performance of the test is ensured.
In this embodiment, the horizontal loading device 4 is accurate to + -1%, and the speed can be adjusted to be 0.1-50 mm/min. After the horizontal preload is applied, the vertical pressure is gradually increased until the target value is reached after about 1 minute. And continuously collecting displacement data of the geosynthetic material by using a displacement sensor after the loading process is finished, continuously testing according to the specified testing time, and automatically collecting and recording related data once every 1 minute until the test is finished.
Because the test device for creep performance of the geosynthetic material adopted in this embodiment has the characteristic that the height of the test port 23 is adjustable, in a specific test, the same batch of geosynthetic material samples can be placed in different soil heights to respectively perform creep performance tests. For example, the creep performance data of the geosynthetic material can be tested by placing the geosynthetic material at the positions with the scales of 1/4, 1/3, 1/2, 2/3 and 3/4 on the fixed side wall 21, comparing the five sets of data, and calculating the creep performance data under the real soil environment according to the simulation test proportion, so as to obtain the creep performance change curves of the geosynthetic material under the conditions of different soil depths.
Further, after each test is completed, the horizontal loading device 4 and the clamp 5 are adjusted in horizontal state, so that the effects of further reducing test errors and improving test precision are achieved.
The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the embodiments and scope of the present invention, and it should be appreciated by those skilled in the art that equivalent substitutions and obvious variations may be made using the teachings of the present invention, which are intended to be included within the scope of the present invention.
Claims (9)
1. A geosynthetic creep performance testing device, comprising: the device comprises a shell (1), a test box (2), a vertical loading device (3), a horizontal loading device (4), a clamp (5), a temperature control assembly (6) and a control system;
The test box (2) is arranged on a test bed (11) at the bottom of the shell (1); the test box (2) comprises a pair of fixed side walls (21) and a pair of adjustable side walls (22), and a height-adjustable test port (23) is arranged on the adjustable side walls (22);
The vertical loading device (3) is positioned above the test box (2), and the fixed end of the vertical loading device is arranged on a transverse frame at the top of the shell (1); the movable end of the vertical loading device (3) is used for applying vertical pressure to soil in the test box (2);
The horizontal loading device (4) is positioned on two sides of a pair of adjustable side walls (22) of the test box (2), and is arranged on the test bed (11) through a supporting frame (12); the movable end of the horizontal loading device (4) is connected with a clamp (5), and the clamp (5) is provided with a clamping jaw (51) for clamping a geosynthetic material sample;
A height adjusting mechanism (41) is arranged between the horizontal loading device (4) and the supporting frame (12); the height adjusting mechanism (41) is used for adjusting the height of the horizontal loading device (4) to enable the height of the horizontal loading device (4) to be consistent with the height of the test port (23);
the control system comprises a power supply, a displacement sensor, a tension sensor, a temperature regulator, a display screen and a control panel;
the adjustable side wall (22) of the test box (2) comprises an adjusting frame (221), a top fixing plate (222), a bottom fixing plate (223) and a plurality of sliding plates (224);
slide rails for the sliding plates (224) to move are arranged on two sides of the adjusting frame (221); the test port (23) is formed between adjacent slide plates (224), between the slide plates (224) and the top fixing plate (222), or between the slide plates (224) and the bottom fixing plate (223) by moving the slide plates (224).
2. The test device according to claim 1, characterized in that the test port (23) is located at 1/4~3/4 of the height of the test box (2).
3. Testing device according to claim 1, characterized in that the fixed side wall (21) of the testing box (2) is made of a high-strength transparent material, and that the edge of the fixed side wall (21) adjacent to the adjustable side wall (22) is provided with a scale (212).
4. The testing device according to claim 1, characterized in that the vertical loading device (3) is a hydraulic servo loading device comprising a loading plate (31) at the bottom of the movable end, the loading plate (31) being adapted to apply a vertical pressure to the soil in the testing box (2).
5. The test device according to claim 1, wherein the horizontal loading device (4) comprises a horizontal hydraulic servo device, the horizontal loading device (4) is used for providing a pre-loading tension for the geosynthetic material sample, and the tension rate provided by the horizontal loading device (4) is 0.1-50 mm/min.
6. The testing device according to claim 1, wherein the height adjusting mechanism (41) is an electric servo telescopic rod, the fixed end of which is mounted on the top plate of the supporting frame (12), and the movable end of which is connected with the horizontal loading device (4).
7. The testing device according to claim 1, wherein the temperature control assembly (6) comprises a temperature control box (61) covered outside the testing box (2), and the temperature adjustment range in the temperature control box (61) is-20-99 ℃.
8. A testing method based on the testing device of the creep properties of a geosynthetic material according to any one of claims 1 to 7, comprising the steps of:
s1, adjusting the positions of the test ports (23) on a pair of adjustable side walls (22) and the height of a horizontal loading device (4) to enable the positions of the test ports and the height of the horizontal loading device to be on the same horizontal line;
S2, paving a first layer of soil to be flush with the horizontal loading device (4);
S3, transversely placing the geosynthetic material sample in a test box (2) filled with soil, and clamping two ends of the geosynthetic material sample by using clamping jaws (51) of a clamp (5);
s4, laying a second layer of soil to be flush with the top of the fixed side wall (21);
S5, adjusting the temperature control assembly (6) to set a test temperature, starting the vertical loading device (3), and applying preset pressure to soil in the test box (2);
And S6, data acquisition is carried out at intervals of a certain time until the time required by the test is reached, and the test is ended.
9. The test method according to claim 8, wherein: before the step S5, the method further includes the following steps: and (3) applying a preloading pulling force to the geosynthetic material sample by using a horizontal loading device (4) to enable the geosynthetic material sample to generate 1% tensile strength preloading, recording a pulling force value by using a pulling force sensor, and recording corresponding displacement by using a displacement sensor.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107356482A (en) * | 2017-07-31 | 2017-11-17 | 石家庄铁道大学 | Test the test platform of Creep of Geosynthetics performance |
| CN109187223A (en) * | 2018-11-21 | 2019-01-11 | 石家庄铁道大学 | Test the testing equipment and test method of Creep of Geosynthetics performance |
| CN113049399A (en) * | 2021-03-12 | 2021-06-29 | 广西科技大学 | Geosynthetic material multifunctional creep tester and test method thereof |
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| AU2003257232A1 (en) * | 2002-08-26 | 2004-03-11 | James Hardie International Finance B.V. | Soil test box |
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| CN107356482A (en) * | 2017-07-31 | 2017-11-17 | 石家庄铁道大学 | Test the test platform of Creep of Geosynthetics performance |
| CN109187223A (en) * | 2018-11-21 | 2019-01-11 | 石家庄铁道大学 | Test the testing equipment and test method of Creep of Geosynthetics performance |
| CN113049399A (en) * | 2021-03-12 | 2021-06-29 | 广西科技大学 | Geosynthetic material multifunctional creep tester and test method thereof |
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| 土工合成材料的蠕变特性和试验方法;王钊;岩土力学;20040530;全文 * |
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