Large-scale dynamic model for aeolian sand high-fill roadbed

Abstract

The utility model relates to the technical field of dynamic models, and particularly discloses an aeolian sand high-fill roadbed large-scale dynamic model which comprises a model groove, a fine sand foundation is arranged at the bottom end of the inner groove wall of the model groove, five layers of model roadbeds are arranged at the top end of the fine sand foundation, and two test sensors are respectively installed in the five layers of model roadbeds. Settlement rods are connected in the five layers of model roadbeds in a penetrating manner; according to the utility model, the model tank is arranged, and the fine sand foundation, the model roadbed, the steel plate, the test sensor and the settlement rod are arranged in the model tank, so that the change rules of the dynamic stress, the overall deformation and the slope stability of the roadbed under the cyclic load repetition effect are effectively analyzed; the construction standards of the slope ratio and the roadbed height of the aeolian sand roadbed are provided, guarantee is provided for the design of the expressway aeolian sand roadbed in the desert area, the uncontrollability of some factors of field tests is solved, and the accuracy of model tests is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of dynamic models, and in particular relates to a large-scale dynamic model of a high-fill roadbed of aeolian sand. Background Art

[0002] Field tests are the basic means of studying the dynamic characteristics of roadbeds. They can provide first-hand information and are very important for in-depth research on the dynamic characteristics of roadbeds. Most field tests are used to explore the dynamic characteristics of roadbeds.

[0003] However, indoor testing is the most effective method to study the dynamic characteristics of roadbed. Although field testing is the most direct, it has many limitations. There are many factors that affect the dynamic characteristics of roadbed. At present, the models used in many indoor tests are only a small disturbance sample made of roadbed filler. There is a size effect, the test data is not accurate, and it is impossible to simulate the effect of vehicle load on the roadbed. It is impossible to analyze the overall dynamic characteristics of the roadbed and the stability of the slope, and the influencing factors of the roadbed itself cannot be considered. Utility Model Content

[0004] The utility model aims to provide a large-scale dynamic model of aeolian sand high-fill roadbed to solve the problems raised in the above-mentioned background technology.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] A large-scale dynamic model of aeolian sand high-fill roadbed, comprising:

[0007] Model slot;

[0008] A fine sand foundation is arranged at the bottom end of the inner groove wall of the model groove, a five-layer model roadbed is arranged at the top end of the fine sand foundation, and two test sensors are respectively installed in the five-layer model roadbed;

[0009] Settlement rods are interspersed and connected in the five layers of the model roadbed, and a steel plate is arranged on the top of the model roadbed of the top layer.

[0010] Preferably, the test sensors are arranged in two rows.

[0011] Compared with the prior art, the beneficial effects of the utility model are:

[0012] (1) The article effectively analyzes the changing laws of the dynamic stress, overall deformation and slope stability of the roadbed under the repeated action of cyclic loads, and proposes construction standards for the slope ratio and roadbed height of the aeolian sand roadbed, which provides a guarantee for the design of aeolian sand roadbeds on highways in desert areas.

[0013] (2) Through similarity theory, similarity coefficients are obtained to conduct large-scale model tests, which solves the uncontrollability of some factors in field experiments. Model tests can control external conditions and change the properties of soil samples, thereby conducting dynamic characteristic tests under multiple factors and multiple working conditions. According to similarity theory, physical quantity ratios are converted. When a reasonable similarity ratio is selected, the model test can have a higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a three-dimensional diagram of the utility model;

[0015] In the figure: 1. Settlement rod; 2. Fine sand foundation; 3. Model roadbed; 4. Model trough; 5. Steel plate; 6. Test sensor. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] Embodiment 1:

[0018] See also Figure 1 As shown, a large-scale dynamic model of aeolian sand high-fill roadbed includes:

[0019] Model slot 4;

[0020] A fine sand foundation 2 is arranged at the bottom of the inner groove wall of the model groove 4, a five-layer model roadbed 3 is arranged at the top of the fine sand foundation 2, and two test sensors 6 are respectively installed in the five-layer model roadbed 3;

[0021] The five layers of the model roadbed 3 are interlaced with the settlement rods 1, and the top of the top layer of the model roadbed 3 is provided with a steel plate 5;

[0022] The test sensors 6 are arranged in two rows.

[0023] As can be seen from the above, the model roadbed 3 is composed of a slope and a roadbed. The steel plate 5 is set at the load action position on the top model roadbed 3 to simulate the wheel action. Its area is equivalent to the wheel action area. The model trough 4 is set to be 1.2 meters high, 1 meter wide and 2.5 meters long. The model roadbed 3 is 1.0 meters high, the fine sand foundation 2 is 10 cm thick, and the height of the settlement rod 1 is 1.1 meters.

[0024] The filler of the model roadbed 3 is aeolian sand transported from the on-site desert area. First, fill the bottom surface of the model groove 4 with fine sand foundation 2, fill it to a height of 10 cm, and tamp it. When the roadbed filling height in the model groove 4 reaches 30 cm, 50 cm, 70 cm, 90 cm and 110 cm respectively, tamp it, and then select two different positions to test the compaction by sand filling method to ensure that the compaction of all test positions reaches 96% of the designed compaction. The compaction of each layer is controlled by strict quality control.

[0025] After the roadbed in the model groove 4 is filled and compacted, the test sensors 6 are placed in groups of two in the five-layer model roadbed 3 and arranged in two rows. After one layer is placed, the next layer is filled and compacted. The previous step is repeated. When the model roadbed 3 is filled and compacted, the settlement rod 1 is inserted into the model roadbed 3 in a vertical state.

[0026] In order to prevent the slope from sliding during the test and ensure the stability of the roadbed, the aeolian sand roadbed slope should be protected. In the test, wooden boards were used to simulate clay edging materials.

[0027] The test sensors 6 are buried on the surface of the roadbed, the middle of the roadbed and the bottom surface of the roadbed respectively. The dynamic stress, elastic deformation and permanent deformation are tested. The dynamic stress is measured using a BW pressure box with a measuring range of 60kPa. The dynamic deformation test uses a settlement rod 1 pre-arranged in the model, and the vertical dynamic deformation of the settlement rod 1 is measured by a displacement sensor. For the cumulative settlement test, in order to ensure the stability of the measured cumulative settlement, three micrometers for measuring the permanent displacement of the roadbed surface are installed on the roadbed surface. The cumulative settlement is read manually at the agreed number of vibrations.

[0028] Working principle: A total of ten test locations are selected. According to the specifications, since the strength and stiffness of the pavement structure layer are much greater than that of the roadbed layer, the fill embankment and foundation have formed a weak underlying layer relative to the pavement structure layer. Therefore, when determining the dynamic stress level of the vehicle load transferred to the top surface of the roadbed, it is necessary to first consider the diffusion effect of the stress in the process of load transmission from the road to the embankment layer. The stress diffusion angle can be determined according to the modulus ratio between the upper and lower layers, and then the force transmitted to the top surface of the roadbed under the standard axle load is calculated. After calculation, the equivalent load size of the highway vehicle load transferred from the road surface to the top surface of the roadbed is about 8.5KPa. Considering heavy traffic, 20KPa is used as the long-term dynamic load value;

[0029] The layered settlement method considering lateral deformation and slope ratio is used to calculate and predict the settlement of high, aeolian sand filled roadbed. The specific method is: through the relationship between lateral displacement and central settlement, it can be deduced that if the lateral displacement is calculated, the magnitude of its vertical displacement can be determined based on the ratio relationship. According to this theory, the passive earth pressure generated by the roadbed slope is used as the load, and the layered sum settlement method is used to calculate the magnitude of its lateral deformation. Then the vertical displacement is derived based on the ratio, and finally the slope ratio parameter is taken into account for fitting.

[0030] In order to simulate the dynamic load effect of vehicle load on high-fill aeolian sand roadbed, the vehicle NVH laboratory dynamic loading system is used to apply dynamic cyclic load to the compacted roadbed. The loading system includes MTS channel servo test machine control system, hydraulic power system, reaction steel frame beam and actuator. The maximum load that the MTS test machine can provide is 100kN, the load accuracy is ±1% of the indicated value, the actuator stroke is ±25mm, the displacement accuracy is ≤±1%FS, and the excitation frequency is 0.01~150Hz. Different loading waveform signals can be generated through control system programming. This model test uses sinusoidal cyclic dynamic load, and the corresponding loading waveform can be selected according to the specific situation.

[0031] The loading frequencies are set to 0.5, 1, 3 and 5 Hz, representing different driving speeds respectively. Different dynamic stress amplitudes are set at different slope ratios and roadbed heights. The loading is repeated 100,000 times. When loading to 1,000 times, 5,000 times, 10,000 times, 50,000 times and 100,000 times respectively, the test data of each sensor is read through the data acquisition system. If any abnormality is found in the test, the test should be stopped in time to troubleshoot the problem before the test can be carried out again.

[0032] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A large-scale dynamic model of aeolian sand high-fill roadbed, characterized in that: include: Model slot (4); A fine sand foundation (2) is arranged at the bottom end of the inner groove wall of the model groove (4), a five-layer model roadbed (3) is arranged at the top end of the fine sand foundation (2), and two test sensors (6) are respectively installed in the five-layer model roadbed (3); The five layers of the model roadbed (3) are connected together with settlement rods (1) inserted therein, and a steel plate (5) is arranged at the top of the top layer of the model roadbed (3).

2. A large-scale dynamic model of aeolian sand high-fill roadbed according to claim 1, characterized in that: The test sensors (6) are arranged in two rows.

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