Reinforced retaining wall testing device considering traffic load and freeze-thaw cycle effect

Abstract

The utility model discloses a reinforced soil retaining wall testing device considering traffic load and freeze-thaw cycle effects. The reinforced soil retaining wall testing device comprises a model box, a loading device, a cycle freeze-thaw box, a reinforced soil retaining wall model and a detection device, a cavity for arranging a reinforced soil retaining wall model is formed in the model box, and a temperature control device is arranged at the bottom of the model box and used for controlling the temperature of a soil body at the bottom of the reinforced soil retaining wall model; the model box is arranged in the circulating freezing and thawing box, the circulating freezing and thawing box is used for applying a freezing and thawing circulating effect to the reinforced soil retaining wall model, and the loading device is arranged at the top of the model box and used for applying a load to the reinforced soil retaining wall model; the detection device comprises a sensor and an image acquisition device, the sensor is embedded in the reinforced soil retaining wall model, and the image acquisition device is used for acquiring a deformation image of the reinforced soil retaining wall model; the stress performance of the reinforced retaining wall under different traffic loads and freezing and thawing temperatures can be simulated, then the damage mechanism of the reinforced retaining wall is researched, and the structure of the reinforced retaining wall is optimized according to the research result.

Description

Technical Field

[0001] The utility model relates to the technical field of construction equipment, in particular to a reinforced retaining wall testing device taking into account traffic load and freeze-thaw cycle effects. Background Art

[0002] Reinforced earth retaining walls are widely used in roadbed reinforcement projects due to their many advantages such as simple construction, low cost, and beautiful appearance. During their service life, reinforced earth retaining walls often experience varying degrees of lateral deformation, threatening traffic safety. Therefore, it is necessary to study the actual stress and deformation of reinforced earth retaining walls.

[0003] Reinforced earth retaining wall tests include prototype tests and scaled model tests. Prototype tests can best reflect the actual stress and deformation of the structure, but prototype tests require a lot of manpower and material resources, are expensive, and are costly, which limits their application. Therefore, scaled model tests are an important method for studying retaining wall structures, that is, making a proportional retaining wall model for load testing. The existing test device fixes the retaining wall model and then performs a load test. First, the existing test device is prone to deformation on both sides during the test, resulting in load dispersion, making the test data inaccurate, and the operation process is complicated. In addition, the existing test device does not consider the impact of the climate environment on the retaining wall in special areas. For example, in the seasonal frozen soil area of ​​Xinjiang, due to periodic temperature changes, the retaining wall is affected by the freeze-thaw cycle for a long time. The solid-liquid phase change of water during the freeze-thaw process causes the volume change of the soil and structural damage. In this case, the existing test device cannot truly reflect the actual stress and deformation data of the reinforced earth retaining wall. Utility Model Content

[0004] In response to the problems existing in the prior art, the utility model provides a reinforced retaining wall test device that takes into account traffic loads and freeze-thaw cycle effects. It can simulate the stress performance of reinforced retaining walls under different traffic loads and freeze-thaw temperatures, and then study their failure mechanism.

[0005] The utility model is realized through the following technical solutions:

[0006] A reinforced retaining wall test device that takes into account traffic loads and freeze-thaw cycle effects includes a model box, a loading device, a freeze-thaw cycle box, a reinforced retaining wall model, and a detection device;

[0007] The model box is formed with a cavity for setting the reinforced earth retaining wall model, and a temperature control device is provided at the bottom of the model box for controlling the temperature of the bottom soil of the reinforced earth retaining wall model;

[0008] The model box is arranged in a freeze-thaw cycle box, which is used to apply freeze-thaw cycles to the reinforced soil retaining wall model. The loading device is arranged on the top of the model box, which is used to apply loads to the reinforced soil retaining wall model.

[0009] The detection device comprises a sensor and an image acquisition device, the sensor is embedded in the reinforced earth retaining wall model, and the image acquisition device is used to acquire a deformation image of the reinforced earth retaining wall model.

[0010] Preferably, the model box is an open structure at the top and one side, and the wall panels of the reinforced earth retaining wall model are located at the opening positions of the side walls of the model box.

[0011] Preferably, an observation window is provided on the side wall of the model box, and a heat preservation device is provided in the interlayer of the side wall of the model box.

[0012] Preferably, the temperature control device includes a heat preservation plate, a load-bearing plate and a temperature control box;

[0013] The insulation board is arranged at the inner bottom of the model box, the bearing board is arranged on the top of the insulation board, the bearing board is embedded with an insulation coil, and the insulation coil is connected to the temperature control box.

[0014] Preferably, a supporting device is provided on the top of the model box, the loading device is connected to the supporting device, and the supporting device is slidably connected to the top of the model box for adjusting the position of the loading device.

[0015] Preferably, the support device includes a column and a beam;

[0016] Two columns are spaced apart and arranged on the top of the side wall of the model box, two ends of the crossbeam are fixedly connected with the two columns, and a loading device is arranged on the crossbeam and located on the top of the reinforced earth retaining wall model.

[0017] Preferably, the lower end of the column is connected to the model box through a track structure.

[0018] Preferably, the columns are provided with a plurality of connection holes for connecting to the cross beams at intervals from top to bottom.

[0019] Preferably, the loading device includes an electromagnetic hammer, which is connected to an intelligent operating system via a current controller.

[0020] Preferably, the sensors include a dynamic acceleration sensor, a dynamic displacement sensor, a temperature sensor, a displacement meter, a strain gauge, a vertical earth pressure cell and a horizontal earth pressure cell.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] The utility model provides a reinforced retaining wall test device which takes traffic load and freeze-thaw cycle effects into consideration. The test device comprises the following steps: a model box is arranged in a cyclic freeze-thaw box; a temperature control device is arranged at the bottom of the model box to control the temperature of the bottom of the reinforced earth retaining wall model to simulate the temperature of a constant temperature area in a deep layer of a roadbed; a cyclic freeze-thaw box is used to apply cyclic freeze-thaw effects to the surface layer of the reinforced earth retaining wall model; a loading device is arranged on the top of the model box to simulate the force of the traffic load on the reinforced earth retaining wall model; the test device simultaneously applies traffic load and freeze-thaw cycle effects to the reinforced retaining wall, accurately simulates the deformation process of the reinforced retaining wall under the condition of double forces, and provides accurate theoretical data for the structural optimization of the reinforced retaining wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural diagram of the reinforced retaining wall test device of the utility model;

[0024] Figure 2 This is a structural diagram of the model box of the utility model;

[0025] Figure 3 It is a three-dimensional schematic diagram of the model box of the utility model;

[0026] Figure 4 This is a schematic diagram of the structure of the double-layer vacuum glass of the utility model;

[0027] Figure 5 This is a schematic structural diagram of the thermal insulation interlayer of the utility model;

[0028] Figure 6 This is a schematic structural diagram of the temperature control device of the present utility model;

[0029] Figure 7 This is a schematic structural diagram of the electromagnetic loading device of the utility model;

[0030] Figure 8 This is a schematic diagram of the arrangement of the sensor of the present utility model.

[0031] In the figure: model box 1, support device 2, electromagnetic loading device 3, cyclic freeze-thaw box 4, reinforced soil retaining wall model 5, high-definition camera 6, bottom plate 101, baffle 102, back plate 103, steel frame 104, insulation board 106, back plate 107, insulation interlayer 108, temperature control device 109, polystyrene foam frame 1081, tempered glass 1082, tempered glass 1083, polystyrene foam interlayer frame 1084, polystyrene foam board 1091, load-bearing board 1092 , insulation coil 1093, water pump 1094, temperature control box 1095, polystyrene foam board 106, column 201, beam 202, bolt 203, electromagnetic hammer 301, current controller 302, intelligent operating system 303, dynamic acceleration sensor 501, dynamic displacement sensor 502, temperature sensor 503, displacement meter 504, reinforcement strip 505, wall panel 506, backfill soil 507, strain gauge 508, vertical soil pressure box 509, horizontal soil pressure box 510. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings, which are intended to explain rather than limit the present invention.

[0033] See Figure 1-8 A reinforced retaining wall test device considering traffic loads and freeze-thaw cycle effects includes a model box 1, a support device 2, an electromagnetic loading device 3, a cyclic freeze-thaw box 4, a reinforced soil retaining wall model 5, and a high-definition camera 6.

[0034] The reinforced earth retaining wall model 5 is arranged in a model box 1, the model box 1 is located in a cyclic freeze-thaw box 4, the support device 2 is arranged on the top of the reinforced earth retaining wall model box 1, the electromagnetic loading device 3 is connected to the support device 2, and the high-definition camera 6 is facing the reinforced earth retaining wall model 5 for collecting real-time images of the test process of the reinforced earth retaining wall model 5.

[0035] A cavity for accommodating the reinforced earth retaining wall model 5 is formed in the model box 1. An observation window is provided on the side wall of the model box 1. A supporting device is provided on the top of two mutually parallel side walls of the model box. The electromagnetic loading device 3 is located on the top of the reinforced earth retaining wall model 5.

[0036] See Figure 2-5The model box 1 includes a base plate 101, a steel frame 104, and a rear plate 107. The two steel frames 104 are perpendicularly and parallelly arranged on either side of the base plate. The rear plate is located at the rear end of the base plate. Both sides of the rear plate 107 are fixedly connected to the two steel frames. The top and front of the model box are open. The base plate 101, steel frames 104, and rear plate 107 are fixedly connected to each other, which can be fixed by riveting or welding. Baffles 102 are welded to the exterior of the two steel frames 104 to prevent the insulation interlayer 109 from shifting outward due to soil pressure.

[0037] The steel frame 104 is provided with a thermal insulation interlayer 108, a polystyrene foam board 106 is provided between the two rear plates (103 and 107), and a temperature control device 109 is provided at the bottom of the bottom plate for controlling the temperature of the constant temperature area of ​​the reinforced earth retaining wall model 5 to simulate the temperature of the constant temperature area at the bottom of the actual roadbed to improve the accuracy of the experiment; the model box realizes two-way freezing of the reinforced earth retaining wall model 5, that is, only the upper and front side models are affected by the ambient temperature.

[0038] The observation window is arranged on two steel frames 104. The observation window is double-layer vacuum glass, including a polystyrene foam interlayer frame 1084, with an inner tempered glass 1082 and an outer tempered glass 1083 respectively arranged on both sides. The inner tempered glass 1082 and the outer tempered glass 1083 are vacuumed. A polystyrene foam frame 1081 is arranged on the outside of the polystyrene foam interlayer frame 1084. The polystyrene foam frame 1081 and the polystyrene foam interlayer frame 1084 are integrally formed. The inner tempered glass 1082 and the outer tempered glass 1083 are flush with the surface of the polystyrene foam frame 1081. A window is opened on the steel frame 104. The double-layer vacuum glass is sealed and fixed to the window. The splicing edge of the tempered glass and the window is sealed to prevent external air from entering. The double-layer vacuum glass has a built-in polystyrene interlayer, which effectively prevents the inner tempered glass from being displaced outward due to soil pressure.

[0039] The polystyrene foam frame 1081 is mounted on the polystyrene foam interlayer frame 1084 and filled in the interlayer of the steel frame. The thermal conductivity coefficient of the polystyrene foam frame 1081 is 0.04 W / (m·K), which is a poor conductor of heat. It is used to prevent heat from entering the glass interlayer frame and avoid contact between the glass and the steel frame, thereby protecting the glass. The thermal conductivity coefficient of the tempered glass is 7 W / (m·K), and the thermal conductivity coefficient of the polystyrene foam interlayer is 0.033 W / (m·K). Although the insulation interlayer is vacuum treated, for technical reasons, the thermal conductivity coefficient of the vacuum layer is 0.005 to ensure structural reliability. W / (m·K); the polystyrene foam frame 1081 is composed of a rectangular plate with a length of 1300 mm, a width of 1000 mm, and a thickness of 50 mm, with the middle hollowed out to form a rectangular plate with a length of 1200 mm, a width of 900 mm, and a thickness of 50 mm; the inner and outer tempered glass are sized at a length of 1200 mm, a width of 900 mm, and a thickness of 10 mm; the polystyrene foam sandwich frame 01084 is composed of a rectangular plate with a length of 1200 mm, a width of 900 mm, and a thickness of 30 mm, with the interior hollowed out to form a rectangular plate with a length of 1100 mm, a width of 800 mm, and a thickness of 30 mm;

[0040] The conversion formula of thermal conductivity coefficient of different materials based on the perpendicular heat transfer direction (1) and the conversion formula of thermal conductivity coefficient of different materials based on the parallel heat transfer direction (2):

[0041] (1)

[0042] (2)

[0043] 、 、 are the thermal conductivity coefficients of different materials respectively; 、 Different material thicknesses; 、 、 are the cross-sectional areas of different materials respectively; is the converted thickness; is the converted thermal conductivity coefficient; is the converted cross-sectional area.

[0044] Calculation shows that the comprehensive thermal conductivity of the polystyrene foam frame is about 0.02W / (m·K), which means there is almost no heat exchange, indicating that the vacuum-treated polystyrene foam frame has a good thermal insulation effect.

[0045] See Figure 6 The temperature control device 109 includes a polystyrene bubble board 1091, an insulation coil 1093, a carrying plate 1092, a water pump 1094 and a temperature control box 1095.

[0046] The polystyrene bubble plate 1091 is set on the top of the base plate, the supporting plate 1092 is set on the polystyrene bubble plate, the insulation coil 1093 is buried in the supporting plate 1092, one end of the insulation coil 1093 is connected to the temperature control box 1095 through the water pump 1094, and the other end of the insulation coil 1093 is connected to the temperature control box 1095 to make the heating medium circulate.

[0047] The polystyrene foam board 1091 prevents heat exchange with the outside, so that the temperature control device only acts on the upper model; the insulation coil 1093 is a copper tube with a wall thickness of 3mm and an inner diameter of 27mm, and contains an insulation agent inside. The insulation agent is an aqueous solution with a mass ratio of ethylene glycol to water between 4:6 and 4.5:5.5, with a freezing point roughly between -22°C and -27°C and a boiling point between 105°C and 106°C, which can serve as an excellent insulation agent. Holes are opened in the insulation board 106 and the rear plate 103 to extend the insulation coil to connect to the water pump 1094 and the temperature control box 1095, and the extended portion is insulated to reduce heat exchange with the environment. The water pump 1094 provides power, and the temperature control box 1095 heats and cools the insulation agent. The temperature of the bottom temperature control device is controlled according to specific circumstances.

[0048] According to the values ​​of the specific heat capacity of ethylene glycol aqueous solution between -20°C and 20°C, the function of the specific heat capacity of ethylene glycol aqueous solution with temperature change (4) is obtained:

[0049] (4)

[0050] is the thermal conductivity coefficient of ethylene glycol aqueous solution; is the specific heat capacity of ethylene glycol aqueous solution; For temperature.

[0051] It can be found that the specific heat capacity of ethylene glycol aqueous solution changes slightly with temperature, and its specific heat capacity is 3.401 kJ / (kg·K).

[0052] The heat transfer of the bottom temperature control device is mainly vertically transferred from the bearing plate 1092 to the upper reinforced earth retaining wall model 5. The other methods are quite different from it, so only this method of transfer is considered. When the output heat is equal to the input heat, the temperature of the temperature control device is kept constant. The heat conductivity coefficient of the bearing plate 1092 is 48.5W / (m·K), and the internal temperature of the temperature control device and the temperature of the upper part of the bearing plate are determined by the temperature sensor. Based on the heat conduction formula (5) and the heat formula (6):

[0053] (5)

[0054] (6)

[0055] 、 are heat output and heat input respectively;

[0056] is the heat transfer coefficient of the load-bearing plate; Main area of ​​the load-bearing plate; Temperature inside the temperature control device; Temperature of the upper part of the load plate; Specific heat capacity of ethylene glycol aqueous solution; Mass rate Temperature of ethylene glycol aqueous solution.

[0057] Available mass rate When meeting the requirements of this device.

[0058] See Figure 7 The support device 2 is movably arranged on the top of the model box 1 and is used to change the loading position of the electromagnetic loading device 3. The electromagnetic loading device 3 includes an electromagnetic hammer 301, a current controller 302 and an intelligent operating system 303; the electromagnetic hammer 301 is connected to the intelligent operating system 303 through the current controller 302.

[0059] The supporting device includes a column 201 and a beam 202. The two columns are respectively installed on the top of the model box steel frame through a track structure. The two columns are connected by a beam. The two ends of the beam are respectively connected to the columns through multiple bolts 203. Multiple bolt holes are arranged on the columns from top to bottom to condition the installation position of the beam so as to control the distance between the electromagnetic hammer and the reinforced earth retaining wall model 5.

[0060] A mounting hole is provided in the middle of the crossbeam 202, and the electromagnetic hammer 301 is set in the mounting hole and fixed by bolts. The closer the distance between the loading position of the electromagnetic hammer and the wall panel 506 is, the more serious the impact on the internal stability of the reinforced earth retaining wall model 5; therefore, the center of the loading position is roughly located between 30 cm and 60 cm from the wall panel.

[0061] The supporting device is connected to the model box through a track structure, which includes a T-slot and a T-block. The T-slot is set at the lower end of the column, and the T-block is set at the top of the steel frame. The T-slot and the T-block are arranged on each other. When the column is moved, the T-slot and the T-block slide against each other.

[0062] The reinforced earth retaining wall model 5 includes backfill 507 and wall panels 506 . The wall panels 506 are arranged at the side wall openings of the model box. The backfill 507 is filled in the model box, and a reinforcement strip 505 is arranged in the backfill 507 .

[0063] See Figure 8The reinforced earth retaining wall model 5 is embedded with a detection device, including a dynamic acceleration sensor 501, a dynamic displacement sensor 502, a temperature sensor 503, a displacement meter 504, a strain gauge 508, a vertical earth pressure box 509 and a horizontal earth pressure box 510.

[0064] Dynamic acceleration sensor 501 and dynamic displacement sensor 502 study the dynamic effects under traffic loads and freeze-thaw cycles; temperature sensor 503 is used to study the temperature pattern inside the retaining wall; displacement meter 504 studies the horizontal displacement and top deformation of the wall panel 506; strain gauge 508 is used to study the deformation of the reinforcement strip 505; vertical earth pressure cell 509 is used to study the vertical stress at the bottom; horizontal earth pressure cell 510 is used to study the horizontal stress on the wall panel 506; in order to facilitate the observation of the deformation of the retaining wall soil, the backfill soil 507 is backfilled with colored sand on the left and right sides.

[0065] A high-definition camera 6 is placed in the freeze-thaw cycle box 4. By adjusting the angle, it can cover the entire side of the reinforced earth retaining wall to record the deformation of the colored sand on the side of the reinforced earth retaining wall and further reflect the deformation of the soil.

[0066] An I-steel is placed in the freeze-thaw cycle box 4, and the reinforced soil retaining wall model box 5 is placed on the I-steel to facilitate the movement and transportation of the model box.

[0067] The following describes the test method of the reinforced retaining wall test device, including the following process:

[0068] A wall panel 506 was constructed on the open side of the model box, and then the model box was filled with backfill soil. During the filling process, colored sand was used on both sides to backfill the soil so that the displacement changes of the soil during the test could be observed through the observation window. At the same time, sensors were buried in the soil during the backfill process. The buried positions of each sensor are shown in the figure. Figure 8 .

[0069] A supporting device and an electromagnetic loading device are installed on the top of the model box, and the position of the electromagnetic loading device is adjusted by the position of the track and the mounting hole. In this embodiment, the center of the loading position is approximately located between 30 cm and 60 cm from the wall panel.

[0070] The temperature control device is started to control the temperature of the constant temperature zone at the bottom of the reinforced earth retaining wall model 5 so that the zone reaches the set temperature.

[0071] The cyclic freeze-thaw box 4 is started to perform cyclic freeze-thaw on the reinforced earth retaining wall model 5. When necessary, the cyclic freeze-thaw action only acts on the wall panel and the top of the reinforced earth retaining wall model 5.

[0072] The electromagnetic hammer 301 is started to continuously apply load to the reinforced earth retaining wall model 5 .

[0073] The control unit collects data from each sensor, while the high-definition camera collects color displacement process. The deformation process of the reinforced earth retaining wall model is analyzed based on the collected data. The structure of the reinforced earth retaining wall model can be optimized based on the analysis results.

[0074] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects, characterized in that: It includes a model box, a loading device, a freeze-thaw cycle box, a reinforced soil retaining wall model and a detection device; The model box is formed with a cavity for setting the reinforced earth retaining wall model, and a temperature control device is provided at the bottom of the model box for controlling the temperature of the bottom soil of the reinforced earth retaining wall model; The model box is arranged in a freeze-thaw cycle box, which is used to apply freeze-thaw cycles to the reinforced soil retaining wall model. The loading device is arranged on the top of the model box, which is used to apply loads to the reinforced soil retaining wall model. The detection device comprises a sensor and an image acquisition device, the sensor is embedded in the reinforced earth retaining wall model, and the image acquisition device is used to acquire a deformation image of the reinforced earth retaining wall model.

2. A reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 1, characterized in that: The model box is a structure with openings on the top and one side, and the wall panels of the reinforced earth retaining wall model are located at the openings on the side walls of the model box.

3. A reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 1, characterized in that: An observation window is provided on the side wall of the model box, and a heat preservation device is provided in the interlayer of the side wall of the model box.

4. A reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 1, characterized in that: The temperature control device includes a heat preservation plate, a load-bearing plate and a temperature control box; The insulation board is arranged at the inner bottom of the model box, the bearing board is arranged on the top of the insulation board, the bearing board is embedded with an insulation coil, and the insulation coil is connected to the temperature control box.

5. The reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 1 is characterized in that: A supporting device is provided on the top of the model box, and the loading device is connected to the supporting device. The supporting device is slidably connected to the top of the model box and is used to adjust the position of the loading device.

6. A reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 5, characterized in that: The supporting device includes a column and a beam; Two columns are spaced apart and arranged on the top of the side wall of the model box, two ends of the crossbeam are fixedly connected with the two columns, and a loading device is arranged on the crossbeam and located on the top of the reinforced earth retaining wall model.

7. A reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 6, characterized in that: The lower end of the column is connected to the model box through a track structure.

8. A reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 7, characterized in that: The columns are provided with a plurality of connection holes for connecting with the cross beams at intervals from top to bottom.

9. The reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 1 is characterized in that: The loading device includes an electromagnetic hammer, which is connected to an intelligent operating system through a current controller.

10. The reinforced retaining wall test device considering traffic load and freeze-thaw cycle effects according to claim 1, characterized in that: The sensors include a dynamic acceleration sensor, a dynamic displacement sensor, a temperature sensor, a displacement meter, a strain gauge, a vertical earth pressure box and a horizontal earth pressure box.

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