CN105738599A

CN105738599A - Landslide test device

Info

Publication number: CN105738599A
Application number: CN201610322721.3A
Authority: CN
Inventors: 刘吉夫; 邓志飞; 石瑶; 邢颖; 高慧; 郭兰兰
Original assignee: Beijing Normal University
Current assignee: Beijing Normal University
Priority date: 2015-05-12
Filing date: 2015-05-12
Publication date: 2016-07-06
Anticipated expiration: 2035-05-12
Also published as: CN105738599B

Abstract

The invention provides a landslide test device. The landslide test device comprises an airflow generator arranged above the slope of a geotechnical model, wherein the airflow generator is in a conical cylinder structure; at least one tangential air inlet is formed in the lower part of the airflow generator and an air outlet is formed in the upper part of the airflow generator; the airflow generator is connected with a model box by a first connecting rod and a second connecting rod; a wind inlet formed in the top of the model box is formed in the top of the first connecting rod; a wind outlet formed in the top of the model box is formed in the top of the second connecting rod; the wind inlet and the wind outlet are in a horn-shaped structure; the wind inlet is connected with the tangential air inlets by a pipeline; the wind outlet is connected with the air outlet by a pipeline. The device used for landslide geotechnical model tests, which is provided by the invention, can generate airflow outside the geotechnical model, so that the impacts of extreme airflow conditions, such as typhoon and tornado, on landslide can be simulated in centrifugal model tests.

Description

Landslide test device

Technical Field

The invention relates to the technical field of landslide physical models, in particular to a device for a landslide geotechnical model test.

Background

In the research work of the landslide mechanism, the used method can be mainly summarized as follows: the method comprises the following steps of site investigation and test, site monitoring, theoretical analysis and numerical calculation, physical model test and the like. Due to the complexity of the landslide forming mechanism, the physical model test is one of the important research means for reproducing the occurrence of landslide.

A landslide physical model test belongs to the field of geomechanical model tests, and the theory of the landslide physical model test is derived from a structural model test. The landslide model test is a test technology aiming at a landslide which is a specific research object in a geomechanical model test, the development of the landslide model test is subjected to test stages such as a frame type model test, a bottom surface friction model test, an on-site three-dimensional and full-scale model test, a water seepage force model test, a geotechnical centrifugal model test and the like, and most of the geomechanical model tests commonly used at home and abroad at present are in two forms of the frame type model test and the centrifugal model test.

In the centrifugal model test, because the centrifugal force generated by the high-speed rotation of the geotechnical centrifuge is used for simulating gravity, under the Ng condition, the stress and the strain of a small-size centrifugal model can be the same as or similar to those of a prototype, so that the centrifugal model test is widely applied to landslide research, and a great deal of documents are disclosed in the prior art for simulating earthquake and rainfall conditions through a vibrating table and a rainfall device in the centrifugal model test, such as a rainfall device for the geotechnical centrifugal model test disclosed in Chinese patent CN204108697U, a rainfall simulation method for the centrifugal model disclosed in CN104391103A and a device thereof; however, there is no relevant research on how to simulate extreme airflow conditions such as typhoon and tornado in a centrifugal model test so as to study the influence of the extreme airflow conditions on landslide.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a landslide test apparatus to reduce or avoid the aforementioned problems.

In order to solve the technical problem, the invention provides a landslide test device which is arranged on a model box for placing an earth model and comprises an air flow generator arranged above a slope of the earth model, wherein the air flow generator is of a cone-shaped structure, at least one tangential air inlet is arranged below the air flow generator, an air outlet is arranged above the air flow generator, the air flow generator is connected with the model box through a first connecting rod and a second connecting rod, an air collecting opening is formed in the top of the first connecting rod and is positioned at the top of the model box, an air outlet is formed in the top of the second connecting rod and is positioned at the top of the model box, the air collecting opening and the air outlet are of a horn-shaped structure, the air collecting opening is connected with the tangential air inlet through a pipeline, and the air outlet is connected with the air outlet through a pipeline.

Preferably, the air outlet is provided with a solenoid valve.

Preferably, the air collecting opening is provided with an electromagnetic valve.

Preferably, the tangential air inlet is spaced from the bottom edge of the flow generator by a distance no less than 1/8 of the height of the flow generator.

Preferably, the tangential air inlet has an angle of inclination of 3-8 degrees to the base of the airflow generator.

Preferably, the tangential air inlet is spaced from a tangent to the inner wall of the flow generator parallel thereto by a distance of 2-5 mm.

The device for landslide geotechnical model test provided by the invention can generate airflow outside the geotechnical model, so that the influence of extreme airflow conditions such as typhoon, tornado and the like on landslide can be simulated in centrifugal model test.

Drawings

The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein,

FIG. 1 shows a schematic of the construction of a geotechnical centrifuge;

fig. 2 is a schematic structural diagram of an apparatus for landslide earth model test according to an embodiment of the present invention;

figure 3 shows a schematic cross-sectional view of a tangential inlet of the airflow generator of figure 2;

figure 4 shows a cross-sectional schematic view of the airflow generator of figure 2.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings. Wherein like parts are given like reference numerals.

FIG. 1 shows a schematic structural view of a geotechnical centrifuge; referring to fig. 1, in a centrifugal model test, a centrifugal model is usually set in a model box, the model box is placed in a basket 1 of a geotechnical centrifuge, when the geotechnical centrifuge rotates at a high speed, a centrifugal acceleration of Ng is generated in the basket 1, and at this time, a small-sized centrifugal model can obtain the same or similar stress and strain as a prototype, and thus, a landslide research on an actual mountain slope can be realized. Typically, when studying landslides, the centrifugal acceleration of the geotechnical centrifuge will be above 30g, even over 50 g. Therefore, high-speed airflow is generated outside the mold box, but because the mold box used in the conventional centrifugal model test is an open structure, the airflow outside the centrifugal model is relatively smooth in the mold box, that is, the airflow outside the centrifugal model is relatively static.

Fig. 2 is a schematic structural diagram of an apparatus for landslide earth model test according to an embodiment of the present invention; figure 3 shows a schematic cross-sectional view of a tangential inlet of the airflow generator of figure 2; figure 4 shows a cross-sectional schematic view of the airflow generator of figure 2. Referring to fig. 2-4, in order to control the air flow outside the centrifugal model and thus simulate the extreme air flow of typhoon, tornado, etc. in the centrifugal model test, the invention provides a device for landslide geotechnical model test, which is arranged on a model box 3 for placing geotechnical model 2, and comprises an air flow generator 41 arranged above the slope of geotechnical model 2, wherein the air flow generator 41 is in a cone structure, at least one tangential air inlet 4111 is arranged below the air flow generator 41, an air outlet 412 is arranged above the air flow generator, the air flow generator 41 is connected with the model box 3 through a first connecting rod 42 and a second connecting rod 43, an air collecting port 44 is arranged at the top of the model box 3, an air outlet 45 is arranged at the top of the model box 3 at the top of the second connecting rod 43, the air collecting opening 44 and the air outlet 45 are both in a horn-shaped structure, the air collecting opening 44 is connected with the tangential air inlet 4111 through a pipeline, and the air outlet 45 is connected with the air outlet 412 through a pipeline.

During installation, a cross beam may be provided on the top of the mold box 3 so as to fix the first connecting rod 42 and the second connecting rod 43, the first connecting rod 42 is located on the windward side of the mold box 3 during rotation, and the second connecting rod 43 is located on the leeward side of the mold box 3 during rotation.

When the geotechnical centrifuge rotates at a high speed, the air flow entering the tangential air inlet 411 through the air collecting opening 44 has a reduced cross section, so that the flow speed is increased, a rotational flow air field is generated in the air flow generator 41 after the air flow enters the air flow generator 41 from the tangential air inlet 411, negative pressure is formed outside the geotechnical model 2, and extreme air flow conditions such as tornado and the like which can generate negative pressure can be simulated. The air flow that generates the swirling flow and the air flow sucked into the air flow generator 41 can be discharged from the air outlet 45 through the air outlet 412 via a duct. So that the gas field environment inside the mold box 3 is not excessively affected.

As shown in fig. 3, the distance d between the passage of the tangential air inlet 411 and the nearest tangent line parallel to the passage of the inner wall of the airflow generator 41 may be set to be 2-5mm, so that the airflow entering from the tangential air inlet 411 can be ensured to generate a swirling flow conveniently, and the tangential air inlet 411 can be processed conveniently.

Referring to fig. 2, in order to calculate the pressure generated by the air flow to the geotechnical model 2, the air flow generator 41 is arranged parallel to the slope of the geotechnical model 2, that is, the air flow generator 41 has an inclination angle corresponding to the bottom of the model box 3, in this case, in order to ensure that the swirling air field in the air flow generator 41 converges to the top of the air flow generator 41, as shown in fig. 4, the distance H1 between the tangential air inlet 411 and the bottom edge of the air flow generator 41 is not less than 1/8 of the height H of the air flow generator 41, and the channel of the tangential air inlet 411 and the bottom edge of the air flow generator 41 have an inclination angle α of 3-8 degrees.

The number of the tangential air inlets 411 may be plural, for example, two or four tangential air inlets may be symmetrically arranged along the center of a circle on the cross section. Therefore, the stability of the central position of the rotational flow air field generated under the conditions of different air inlet flow rates can be ensured.

Referring to fig. 4, the air outlet 412 is only used as an outflow channel of the swirling air flow, so it can be disposed on the side wall of the air flow generator 41 near the top edge, of course, it can also be disposed on the top edge of the air flow generator 41, a solenoid valve can be disposed at the air outlet 412, so that the air outlet 412 can be closed by closing the solenoid valve, when the air outlet 412 is closed, the air entering the air flow generator 41 from the tangential air inlet 411 will overflow onto the geotechnical model 2, so as to simulate the extreme air flow condition of typhoon, etc. which can generate positive pressure.

The air intake 44 may be provided with a solenoid valve (not shown) to adjust the amount of air intake during the test.

The air pressure generated by the device for landslide geotechnical model test provided by the invention in centrifugal test can be measured by arranging air pressure sensors in the air flow generator 41 and the model box.

It should be appreciated by those of skill in the art that while the present invention has been described in terms of several embodiments, not every embodiment includes only a single embodiment. The description is given for clearness of understanding only, and it is to be understood that all matters in the embodiments are to be interpreted as including technical equivalents which are related to the embodiments and which are combined with each other to illustrate the scope of the present invention.

The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations can be made by those skilled in the art without departing from the spirit and principles of the invention.

Claims

1. A landslide test device is arranged on a model box for placing a geotechnical model and is characterized by comprising an airflow generator arranged above a slope of the geotechnical model; the airflow generator is of a cone-shaped structure, at least one tangential air inlet is arranged below the airflow generator, and an air outlet is arranged above the airflow generator; the airflow generator is connected with the model box through a first connecting rod and a second connecting rod, the top of the first connecting rod is provided with an air collecting opening which is positioned at the top of the model box, the top of the second connecting rod is provided with an air outlet which is positioned at the top of the model box, the air collecting opening is of a horn-shaped structure, the air collecting opening is connected with the tangential air inlet through a pipeline, the air outlet is connected with the air outlet through a pipeline, the air outlet is provided with an electromagnetic valve, and the air collecting opening is provided with an electromagnetic valve.