Test system and application of embankment on consolidated soft soil-gravel pile foundation under traffic load

Abstract

The application discloses a kind of test systems of consolidation soft soil-gravel pile foundation embankment under traffic load and application.The test system includes model box, embankment model, material platform, water collecting tank, power loading device, mechanical sensor, data acquisition instrument and image acquisition equipment;Wherein, power loading device is hoisted at the top of model box, embankment model is laid in model box, the mechanical sensor is buried in the inside of embankment model, data acquisition instrument is placed outside model box and is connected with mechanical sensor, at least one side wall plate in the model box is transparent plate, and image acquisition equipment is set towards the transparent plate;The material platform is used to mix configuration or temporary storage of raw material of embankment model;The power loading device is used to apply static load or dynamic load to embankment model.The invention test system is easy to operate, low in cost, high in matching degree, strong in visibility, and accurate and reliable in considering consolidation and loading process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of embankment dynamic test, more particularly, relates to a test system for embankment of consolidated soft soil-gravel pile foundation under traffic load and application. BACKGROUND

[0002] Newly-built embankments are concentrated in coastal areas and southern areas where soft soil is widely distributed. Since soft soil has low strength, poor engineering properties and many geological disasters, it is necessary to reinforce and treat the soft soil foundation embankment. The increase in speed and load puts forward higher requirements for the smoothness of the embankment.

[0003] Gravel pile is a composite foundation reinforcement pile made of gravel or pebble as the main material. Gravel pile belongs to one kind of granular material pile, and is often used to reinforce soft soil foundation due to its characteristics of abundant material, cost saving, convenient construction, superior drainage performance and small post-construction settlement.

[0004] The dynamic response and cumulative deformation mechanism of embankment under traffic load are complex, and there are many subdivided influencing factors and research objects. The research is not mature. The field test has high cost and long cycle, and the size effect of unit test is large. The model test is simple to operate and reliable, and can provide parameter support and verification for numerical simulation and theoretical research. However, the existing test system has the problems of large process simplification error, high cost and many limitations of site conditions, complex operation, weak pertinence and poor visibility. Therefore, it is particularly important to design a matched high-precision visual model test system. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a test system for embankment of consolidated soft soil-gravel pile foundation under traffic load and application, which aims to provide a traffic load test system with simple operation, cost saving and strong visibility for soft soil foundation embankment, so as to realize the test of dynamic response and cumulative deformation of embankment model and understand its law and mechanism.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present application, a test system for embankment of consolidated soft soil-gravel pile foundation under traffic load is provided, which comprises a model box, a material platform, an electric loading device, a mechanical sensor, a data acquisition instrument and an image acquisition equipment; wherein the electric loading device is hoisted at the top of the model box, a drainage assembly is arranged at the bottom of the model box, an embankment model is laid in the model box, the mechanical sensor is embedded in the interior of the embankment model, the data acquisition instrument is arranged outside the model box and connected with the mechanical sensor, at least one side wall plate in the model box is a transparent plate, and the image acquisition equipment is arranged facing the transparent plate; the material platform is used for mixing and configuring or temporarily storing the raw materials of the embankment model; and the electric loading device is used for applying static load or dynamic load to the embankment model.

[0007] Preferably, the front plate of the model box is transparent tempered glass, the back plate is detachable steel plate, and the left and right side plates are steel plates, and one of the left and right side plates is provided with an outlet hole.

[0008] Preferably, a mounting hole is arranged on the top of the model box, a steel support beam provided with corresponding hole positions is fixed on the mounting hole through bolts, and the power loading device is fixed on the beam through bolts.

[0009] Preferably, the drainage assembly comprises drainage valves and a water collecting tank arranged around the bottom of the model box, and the drainage valves are arranged at equal intervals.

[0010] Preferably, the embankment model comprises three layers, a bottom layer of quartz sand underlayer, a middle layer of composite foundation layer, the composite foundation layer comprising soft cohesive soil and replaced gravel pile after consolidation, and an upper layer of graded sand subgrade layer; wherein the soft cohesive soil is obtained by mixing highland clay and water.

[0011] Preferably, the power loading device comprises a servo motor for pre-pressing consolidation, a servo cylinder for traffic dynamic load, and controllers and loading plates matched with the servo motor and the servo cylinder respectively.

[0012] Preferably, the mechanical sensor comprises a soil pressure cell, a displacement sensor, a pore water pressure gauge, an acceleration sensor and a strain gauge.

[0013] Preferably, the height of the material platform is higher than that of the model box, and the material platform comprises a mixer. The material platform is provided with sand and stone fillers and a small mixer with a sliding plate, and the mixer is used for mixing highland clay and water similar to engineering practice, as homogeneous soft cohesive soil before consolidation.

[0014] Preferably, the image acquisition device comprises a high-speed camera and a fixing frame, and is arranged to face the transparent tempered glass front plate of the model box, and is used for continuously shooting the change of the embankment model in the whole test process.

[0015] According to another aspect of the present application, an application of the test system is provided for testing and data acquisition of a consolidated soft soil-gravel pile foundation embankment model under traffic load.

[0016] Preferably, the consolidated soft soil-gravel pile foundation embankment model comprises three layers, a bottom layer of quartz sand underlayer, a middle layer of composite foundation layer, the composite foundation layer comprising soft cohesive soil and replaced gravel pile after consolidation, and an upper layer of graded sand subgrade layer; wherein the soft cohesive soil is obtained by mixing highland clay and water.

[0017] Preferably, the application comprises the following steps:

[0018] (1) Fill the quartz sand underlayer and the soft cohesive soil layer from the material platform to the model box, and bury the mechanical sensors at the preset positions, and connect the mechanical sensors to the data acquisition instrument through wires;

[0019] (2) Start the servo motor in the electric loading device for pre-consolidation, open the drainage valve to drain water into the water collecting tank, and make the soft cohesive soil layer gradually drain and consolidate;

[0020] (3) After the soft cohesive soil layer is consolidated, the soft cohesive soil layer is excavated and replaced, the gravel pile is formed, and the graded sand roadbed layer is continuously filled, and the mechanical sensors are buried at the preset positions, and the mechanical sensors are connected to the data acquisition instrument through wires;

[0021] (4) Start the servo cylinder in the electric loading device for traffic dynamic load to apply traffic excitation load to the embankment model;

[0022] (5) Obtain the data in the data acquisition instrument and the image acquisition equipment.

[0023] Overall, compared with the prior art, the above technical solutions conceived by the present application can at least achieve the following beneficial effects.

[0024] (1) The material platform for mixing raw materials of the embankment model and the test model box are integrated in one system, which is very suitable for mixing raw materials on site to simulate soft soil, and the uniform preparation of the soft cohesive soil layer ensures the consistency between multiple tests, so that the results are more accurate. In addition, the consideration of the pre-consolidation process is close to the engineering practice, so that the results are more reliable and not too simplified.

[0025] (2) The electric loading device in the present application is directly hoisted on the top of the model box, without the need for additional large counterforce frames or counterforce walls, so it is not only easy to disassemble, but also occupies less space. The loading equipment is driven by electricity, without the need for special personnel to operate, without the need for oil cylinders and their supporting pipes and basements used in most current dynamic tests, with lower requirements for the conditions of the test site, without the need for consumption and replacement of oil storage, saving costs and being more sustainable. The servo cylinder for traffic dynamic load has a sufficient loading range, excitation frequency, displacement stroke and waveform type to simulate actual conditions, and has the ability to simulate traffic load, with high adaptability.

[0026] (3) The data acquisition instrument and the image acquisition equipment provided in the present application are helpful for real-time observation of the deformation evolution process of the embankment soil body, with strong visibility.

[0027] (4) The application has wide application range and can be popularized in the related scientific research fields of geotechnical engineering and road engineering, overcomes the defects of poor economy and long cycle of the field test and large size effect of the unit test, and can provide parameter support and verification for numerical simulation and theoretical research. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a structural top view of a test system of a soft soil-gravel pile foundation embankment under traffic load provided by the application;

[0029] Figure 2 is a structural schematic view of cooperation of an embankment model and a loading device of the test system of the soft soil-gravel pile foundation embankment under traffic load provided by the application.

[0030] In all the drawings, the same reference signs are used to represent the same elements or structures, in which: 1 - model box, 101 - transparent tempered glass, 102 - detachable steel plate, 103 - wire outlet hole, 104 - drainage valve, 105 - mounting hole, 2 - embankment model, 201 - quartz sand underlayer, 202 - composite foundation layer, 2021 - soft cohesive foundation soil, 2022 - gravel pile, 203 - graded sand roadbed layer, 3 - material platform, 301 - sand and stone filler, 302 - mixer, 4 - water collecting tank, 5 - electric loading device, 6 - mechanical sensor, 7 - data acquisition instrument, 8 - image acquisition equipment. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the application clearer, the application is further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application. In addition, the technical features involved in each embodiment of the application described below can be combined with each other as long as they do not conflict with each other.

[0032] The embodiment of the application provides a test system of a soft soil-gravel pile foundation embankment under traffic load, referring to Figure 1 and Figure 2 , the test system comprises a model box 1, an embankment model 2, a material platform 3, a water collecting tank 4, an electric loading device 5, a mechanical sensor 6, a data acquisition instrument 7 and an image acquisition equipment 8; wherein the electric loading device 5 is hoisted on the top of the model box 1; the embankment model 2 is laid in the model box 1, the mechanical sensor 6 is embedded in the interior of the embankment model 2, the data acquisition instrument 7 is arranged outside the model box 1 and connected with the mechanical sensor 6, at least one side wall plate in the model box 1 is a transparent plate, and the image acquisition equipment 8 is arranged to face the transparent plate; the material platform 3 is used for mixing and configuring or temporarily storing raw materials of the embankment model 2; and the electric loading device 5 is used for applying static load or dynamic load to the embankment model 2.

[0033] In a feasible mode, the front plate of the model box 1 is a transparent tempered glass 101, the back plate is a detachable steel plate 102, the left and right side wall plates are steel plates, and a wire hole 103 is formed in one of the left and right side wall plates. A mounting hole 105 is arranged at the top of the model box 1, a steel support beam provided with a corresponding hole is fixed on the mounting hole 105 through bolts, and the power loading device 5 is fixed on the beam through bolts.

[0034] Specifically, the drainage valve 104 is arranged around the bottom of the model box 1, and the water collecting tank 4 is arranged outside the four sides of the model box 1. The drainage valves 104 are arranged at equal intervals. In actual application, equal-interval pipes can be extended from the bottoms of the four side wall plates of the model box 1, and the pipes are connected in parallel and drained through a drainage valve, or a drainage valve is arranged on each pipe.

[0035] The embankment model 2 in the embodiment of the application comprises three layers, the bottom layer is a quartz sand underlayer 201, the middle layer is a composite foundation layer 202, the composite foundation layer comprises soft cohesive soil 2021 and replaced gravel pile 2022 after consolidation, and the upper layer is a graded sand embankment layer 203; wherein the soft cohesive soil 2021 is obtained by stirring proportional kaolin and water.

[0036] Further, the power loading device 5 comprises a servo motor for pre-pressing consolidation, a servo cylinder for traffic dynamic load, and controllers and loading plates matched with the servo motor and the servo cylinder respectively; the mechanical sensor 6 comprises a soil pressure cell, a displacement sensor, a pore water pressure gauge, an acceleration sensor and a strain gauge, the soil pressure cell and the acceleration sensor are uniformly arranged in the embankment model 2, the pore water pressure gauge is uniformly arranged in the soft cohesive soil 2021, the displacement sensor is arranged on the upper surface of the embankment model 2, and the strain gauge is attached to the possible geosynthetic material.

[0037] The height of the material platform 3 is higher than that of the model box 1, and the material platform 3 comprises a mixer 302. The image acquisition device 8 comprises a high-speed camera and a fixing frame, and is arranged to face the transparent tempered glass front plate of the model box, and is used for continuously shooting the change of the embankment model in the whole test process.

[0038] Another embodiment of the application provides an application of the test system, which is used for testing and data acquisition of a consolidated soft soil-gravel pile foundation embankment model under traffic load.

[0039] The embankment model of the consolidated soft soil-gravel pile foundation includes three layers, the bottom layer is a quartz sand underlayer 201, the middle layer is a composite foundation layer 202 including soft cohesive foundation soil 2021 and replaced gravel piles 2022 after consolidation, and the upper layer is a graded sand embankment layer 203; wherein the soft cohesive foundation soil 2021 is obtained by stirring high-kaolin clay and water.

[0040] Further, the application comprises the following steps:

[0041] (1) Fill the quartz sand underlayer and the soft cohesive foundation soil layer from the material platform to the model box, and bury the mechanical sensors at the preset positions, and connect the mechanical sensors to the data acquisition instrument through wires;

[0042] (2) Start the servo motor in the electric loading device for pre-consolidation, open the drainage valve to drain water into the water collecting tank, and gradually drain and consolidate the soft cohesive foundation soil layer;

[0043] (3) After the soft cohesive foundation soil layer is consolidated, excavate and replace the soft cohesive foundation soil layer to complete the gravel pile, and continue to fill the graded sand embankment layer, and bury the mechanical sensors at the preset positions, and connect the mechanical sensors to the data acquisition instrument through wires;

[0044] (4) Start the servo cylinder in the electric loading device for traffic dynamic load to apply traffic excitation load to the embankment model;

[0045] (5) Obtain the data in the data acquisition instrument and the image acquisition equipment.

[0046] In construction, the uniform preparation of the soft cohesive foundation soil layer 2021 ensures consistency between multiple groups of tests, making the results more accurate; the consideration of the pre-consolidation process is close to the engineering practice, making the results more reliable; the electric loading devices 5 are all driven by electricity, without the need for oil cylinders and their supporting pipes and basements, without the need for consuming and replacing oil storage, and more sustainable; the electric loading devices 5 are directly mounted on the top of the model box 1 through bolts and mounting holes 105, convenient to disassemble, without the need for counterforce frames or counterforce walls, and with lower requirements for the conditions of the test site; the servo cylinder for traffic dynamic load has a sufficient loading range, excitation frequency, displacement stroke and waveform type to simulate the actual conditions, with high adaptability; the data acquisition instrument 7 and the image acquisition equipment 8 are helpful for observing the deformation evolution process of the embankment soil, with strong visibility.

[0047] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. Use of a test system for embankment of soft soil-gravel pile foundation under traffic load, characterized in that, The application relates to a test system for testing and data acquisition of a cemented soft soil-gravel pile foundation embankment model under traffic load, which comprises a model box (1), a material platform (3), a power loading device (5), a mechanical sensor (6), a data acquisition instrument (7) and an image acquisition device (8). The power loading device (5) is hung on the top of the model box (1), a drainage assembly is arranged at the bottom of the model box (1), an embankment model (2) is laid in the model box (1), the mechanical sensor (6) is embedded in the embankment model (2), the data acquisition instrument (7) is arranged outside the model box (1) and connected with the mechanical sensor (6), at least one side wall plate of the model box (1) is a transparent plate, and the image acquisition device (8) is arranged to face the transparent plate. The material platform (3) is used for mixing and arranging raw materials of the embankment model (2) or temporarily storing the raw materials. The power loading device (5) is used for applying static load or dynamic load to the embankment model (2). The embankment model (2) comprises three layers, the bottom layer is a quartz sand underlayer (201), the middle layer is a composite foundation layer (202) which comprises soft cohesive foundation soil (2021) and replaced gravel piles (2022) after consolidation, and the upper layer is a graded sand subgrade layer (203). The soft cohesive foundation soil (2021) is obtained by stirring highland clay and water. The application comprises the following steps: (1) filling the quartz sand underlayer and the soft cohesive foundation soil layer into the model box from the material platform, embedding the mechanical sensor at a preset position, and connecting the mechanical sensor to the data acquisition instrument through wires; (2) starting the servo motor in the power loading device for pre-pressing consolidation, opening the drainage valve to make water flow into the water collecting tank, and gradually draining and consolidating the soft cohesive foundation soil layer; (3) after the soft cohesive foundation soil layer is consolidated, excavating and replacing the soft cohesive foundation soil layer, completing the gravel pile forming, continuing to fill the graded sand subgrade layer, embedding the mechanical sensor at a preset position, and connecting the mechanical sensor to the data acquisition instrument through wires; (4) starting the servo cylinder in the power loading device for traffic dynamic load, and applying traffic exciting load to the embankment model; (5) acquiring data in the data acquisition instrument and the image acquisition device.

2. Use according to claim 1, wherein The front plate of the model box (1) is transparent tempered glass (101), the back plate is a detachable steel plate (102), the left and right side wall plates are steel plates, and a wire outlet hole (103) is formed in one of the left and right side wall plates.

3. Use according to claim 2, wherein the compound is ###0002### Mounting holes (105) are arranged on the top of the model box (1), steel support beams provided with corresponding hole positions are fixed on the mounting holes (105) through bolts, and the power loading device (5) is fixed on the beams through bolts.

4. Use according to claim 1 or 2, wherein the compound is ###0002### The drainage assembly comprises a drainage valve (104) arranged around the bottom of the model box (1) and a water collecting tank (4) arranged around the outside of the model box (1), and the drainage valves (104) are arranged at equal intervals.

5. The use according to claim 1, wherein The electric loading device (5) includes a servo motor for pre-pressing consolidation, a servo cylinder for traffic dynamic loading, and controllers and loading plates matched with the two respectively; the mechanics sensor (6) includes a soil pressure cell, a displacement sensor, a pore water pressure gauge, an acceleration sensor and a strain gauge.

6. The use according to claim 1, wherein The height of the material platform (3) is higher than that of the model box (1), and the material platform (3) comprises a stirrer (302).

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