Indoor physical model test system for loess collapsibility research

Abstract

The invention relates to the technical field of loess area rock soil testing, and particularly discloses an indoor physical model test system for loess collapsibility research, which comprises a base, at least one subsidence device is arranged on the upper side of the base, the subsidence device comprises a cylindrical mold and a load device, the cylindrical mold is filled with a soil body, and the load device is arranged in the cylindrical mold. The load device applies load to a soil body from an opening in the upper side of the cylindrical mold, the cylindrical mold comprises a supporting ring and a bottom plate, and a cylindrical rubber film cylinder is fixedly connected between the bottom plate and the supporting ring; a plurality of protection plates are arranged on the outer side of the rubber membrane cylinder in an annular array mode and pulled outwards through a tensioning device; and sheet-shaped first pressure sensors are arranged on the inner cylinder wall of the rubber membrane cylinder at intervals. The soil body is filled in the rubber membrane cylinder, after the soil body is immersed into a set amount of water, a load is applied above the soil body through the load device, the outer side of the flexible rubber membrane cylinder is pulled to deform so as to be matched with subsidence deformation of the soil body, and the environment of lateral pressure borne by the soil body underground is simulated, so that the research on the collapsibility of the soil body is more practical.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical testing in loess areas, and particularly to an indoor physical model test system for studying the collapsibility of loess. Background Art

[0002] The collapsibility of loess and its evaluation method have always been technical problems concerned and studied in the field of geotechnical engineering in loess areas. Methods for testing and evaluating the collapsibility of loess and the collapsible deformation of the foundation: taking undisturbed loess in layers on site, testing the collapsibility coefficient based on the soaking collapsibility test of loess specimens under the uniaxial compression and confined deformation stress conditions in the laboratory, first calculating the collapsible deformation of each soil layer with the same collapsibility in layers, and then summing up to evaluate the collapsible deformation of the site foundation.

[0003] In the indoor collapsibility test method, the scale of the specimen is small, and the stress conditions of the specimen under confined deformation compression are ignored. Therefore, there are differences from the changes in stress conditions during the collapsible deformation of the actual formation. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies in the prior art and propose an indoor physical model test system for studying the collapsibility of loess, thereby solving the problems existing in the prior art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: An indoor physical model test system for studying the collapsibility of loess, including a base, at least one subsidence device is provided on the upper side of the base. The subsidence device includes a cylindrical mold and a loading device. The cylindrical mold is filled with soil, and the loading device applies a load to the soil from the upper open end of the cylindrical mold. The cylindrical mold includes a support ring and a bottom plate, and a cylindrical rubber membrane tube is fixedly connected between the bottom plate and the support ring; A plurality of guard plates are arranged in an annular array on the outer side of the rubber membrane tube, and the guard plates are pulled outward through a tensioning device; Sheet-shaped first pressure sensors are arranged at intervals on the inner cylindrical wall of the rubber membrane tube.

[0006] Preferably, the guard plate has an arc-shaped structure. One end of the guard plate is rotatably connected to the base through a rotating shaft. The tensioning device includes a driving ring. The rotating shaft of the guard plate is fixedly connected to a first gear, and the driving ring meshes with the first gear. The driving ring is rotatably connected to the upper side of the base; The driving ring is driven to rotate by conventional power; Fixed rubber columnar filaments are uniformly distributed on the inner arc surface of the guard plate and the outer wall of the rubber membrane tube.

[0007] Preferably, the diameter of the rubber columnar filament gradually decreases from the corner at the upper end of the guard plate far from the first gear towards the first gear.

[0008] Preferably, the load device includes a vertical plate fixedly connected to the upper side of the base. One side of the vertical plate is fixedly connected to a support rod, and the support rod is fixedly connected to a support ring. A chute is provided on one side of the vertical plate, and a slider is slidably connected in the chute. A cylinder is fixedly connected to the upper side of the vertical plate, and the telescopic rod of the cylinder is fixedly connected to the slider; One side of the slider is fixedly connected to a cross bar, the cross bar is fixedly connected to a cylinder body, a cover plate is fixedly connected to the upper side of the cylinder body, at least one through hole is provided on the cover plate, a measuring rod is slidably connected in the through hole, scale lines are provided on the outer side of the measuring rod, a second pressure sensor is fixedly connected to the bottom of the measuring rod, a placement hole is provided at the upper end of the measuring rod, and a counterweight column is provided in the placement hole.

[0009] Preferably, the cover plate is fixedly connected to a side plate, the side plate is arranged corresponding to the measuring rod, and the side plate is threadedly connected to a locking rod.

[0010] Preferably, at least three measuring rods are provided, and an elastic membrane is fixedly connected to the bottom of the cylinder body.

[0011] The advantages of the present invention are as follows: The indoor physical model test system for studying the collapsibility of loess provided by the present invention fills the soil body in the rubber membrane cylinder. After the soil body is immersed in a set amount of water, a load is applied above the soil body through the load device to simulate the collapsible settlement of the soil body, so as to study a reasonable soil improvement plan. Aiming at the defect that the outer wall of the soil body in the conventional test cylinder is restricted by the rigid cylinder, and the stress of the soil body expanding around is quite different from the actual construction environment; when the soil body subsides, the outer side of the flexible rubber membrane cylinder is pulled and deformed to cooperate with the subsidence deformation of the soil body, and an expansion force that can monitor the magnitude of the pressure is applied to simulate the environment of the lateral pressure suffered by the soil body underground, so that the study of the collapsibility of the soil body is more in line with the actual situation.

[0012] The present invention can conveniently adjust the magnitude and position of the subsidence acting force applied to the soil surface, and the binding force on the side of the soil body (simulating the lateral pressure suffered by the soil body in the underground environment) can be easily adjusted, so as to facilitate the theoretical study of the collapsibility of loess. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the basic structure of the present invention; Figure 2 is a schematic diagram of the connection structure of the measuring rod of the load device of the present invention; Figure 3 is the front view of the guard plate of the present invention; In the figure: base - 1; servo motor - 10; cylindrical mold - 2; support ring - 21; bottom plate - 22; rubber membrane cylinder - 23; protection plate - 24; tensioning device - 3; drive ring - 31; first gear - 32; rubber columnar wire - 33; load device - 4; vertical plate - 41; support rod - 42; slider - 44; cylinder - 45; cross bar - 46; cylinder body - 47; cover plate - 48; measuring rod - 5; scale line - 51; second pressure sensor - 52; counterweight column - 53; side plate - 54; locking rod - 55; elastic membrane - 56. Detailed implementation mode

[0014] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Embodiment 1

[0015] As Figures 1-3 shown, an indoor physical model test system for studying the collapsibility of loess provided by the present invention includes a base 1, and at least one settlement device is provided on the upper side of the base 1. The settlement device includes a cylindrical mold 2 and a load device 4. The cylindrical mold 2 is filled with soil, and the load device 4 applies a load to the soil from the upper opening of the cylindrical mold 2. The cylindrical mold 2 includes a support ring 21 and a bottom plate 22, and a cylindrical rubber membrane cylinder 23 is fixedly connected between the bottom plate 22 and the support ring 21; A plurality of protection plates 24 are arranged in an annular array on the outer side of the rubber membrane cylinder 23, and the protection plates 24 are pulled outwards through a tensioning device 3; The inner cylindrical wall of the rubber membrane cylinder 23 is provided with sheet - shaped first pressure sensors at intervals.

[0016] In the present invention, the soil is filled in the rubber membrane cylinder 23, and the soil is sampled from the construction site by using an annular cylindrical mold (the principle of the ring knife method). After the soil is immersed in a set amount of water, a load is applied to the soil from above through the load device 4 to simulate the collapsible settlement of the soil, so as to study a reasonable soil improvement plan. Aiming at the defect that the outer wall of the soil in the conventional test cylinder is restricted by the rigid cylinder, and the stress of the soil expanding around is quite different from the actual construction environment; when the soil settles, the outer side of the flexible rubber membrane cylinder 23 is pulled and deformed to cooperate with the settlement deformation of the soil, and an expansion force that can monitor the pressure magnitude (monitored by the first pressure sensor) is applied to simulate the lateral pressure environment of the soil underground, so that the study of the collapsibility of the soil is more in line with the actual situation. Embodiment 2

[0017] As Figures 1-3As shown in the figure, the guard plate 24 has an arc-shaped structure. One end of the guard plate 24 is rotatably connected to the base 1 through a rotating shaft. The tensioning device 3 includes a driving ring 31. The rotating shaft of the guard plate 24 is fixedly connected to a first gear 32. The driving ring 31 meshes with the first gear 32. The driving ring 31 is rotatably connected to the upper side of the base 1; The driving ring 31 is driven to rotate by conventional power. When two settlement devices are used for simulation tests, the conventional power is a servo motor 10. The main shaft of the servo motor 10 is fixedly connected to a driving gear. The driving rings 31 of the two settlement devices have different outer diameters. Through the gear transmission ratio design of the existing technology, the servo motor 10 can be used to rotate a driving gear by an angle. Due to different transmission ratios, the driving rings 31 of the two settlement devices rotate different angles, and the corresponding guard plate 24 rotates different angles, forming a gap between the guard plate 24 and the rubber membrane cylinder 23 for the soil to push the rubber membrane cylinder 23 outwards to deform, so as to realize multi-level lateral pressure adjustment and adapt to the collapsible loess with different burial depths and the collapsibility research under different lateral soil pressure environments; Rubber columnar filaments 33 are evenly distributed and fixed on the outer wall of the rubber membrane cylinder 23 on the inner arc surface of the guard plate 24. The diameter of the rubber columnar filaments 33 gradually decreases from the corner at one end of the upper side of the guard plate 24 away from the first gear 32 towards the first gear 32.

[0018] Due to different soil burial depths, the greater the lateral soil pressure is towards the lower part. The rubber columnar filaments 33 with smaller diameters are more likely to elongate first by themselves without exerting a pulling effect on the rubber membrane cylinder 23. Since the rubber columnar filaments 33 in the upper part have larger diameters, the length deformation amount of the upper rubber columnar filaments 33 is small when the guard plate 24 rotates, and it can easily drive the rubber membrane cylinder 23 in the upper position to deform, enabling the contacted soil to expand outwards (i.e., the resistance received is small). On the contrary, the rubber columnar filaments 33 at the bottom have small diameters. When the guard plate 24 rotates, the rubber columnar filaments 33 deform first, and the rubber membrane cylinder 23 is not easily deformed outwards. The binding reaction force received by the soil at the bottom inside the rubber membrane cylinder 23 is large, simulating the environment with large lateral soil pressure in the deep soil. Through the gradient design of the diameter of the rubber columnar filaments 33, the collapsibility of the soil under different depth lateral pressure environments is studied. Embodiment 3

[0019] As Figures 1-3 As shown in the figure, the load device 4 includes a vertical plate 41. The vertical plate 41 is fixedly connected to the upper side of the base 1. One side of the vertical plate 41 is fixedly connected to a support rod 42. The support rod 42 is fixedly connected to the support ring 21. A chute is provided on one side of the vertical plate 41. A slider 44 is slidably connected in the chute. A cylinder 45 is fixedly connected to the upper side of the vertical plate 41. The telescopic rod of the cylinder 45 is fixedly connected to the slider 44; One side of the slider 44 is fixedly connected to a cross bar 46, the cross bar 46 is fixedly connected to a cylinder 47, the upper side of the cylinder 47 is fixedly connected to a cover plate 48, the cover plate 48 is provided with at least one through hole, a measuring rod 5 is slidably connected in the through hole, a scale line 51 is provided on the outer side of the measuring rod 5, a second pressure sensor 52 is fixedly connected to the bottom of the measuring rod 5, the second pressure sensor 52 collects the pressure applied to the soil, a placement hole is provided at the upper end of the measuring rod 5, a counterweight column 53 is provided in the placement hole, the counterweight column 53 samples multiple sections of lead columns, and sampling is achieved by increasing the number of lead columns when different counterweights are used.

[0020] The cover plate 48 is fixedly connected to the side plate 54, and the side plate 54 is arranged corresponding to the measuring rod 5. The side plate 54 is threadedly connected to the locking rod 55; before the measuring rod 5 contacts the soil surface, it is supported by the locking rod 55. When the sinking test starts, the locking rod 55 is loosened, and the measuring rod 5 is pressed down by the counterweight column 53 to sink the soil below, and the settlement displacement is recorded by the displacement of the measuring rod 5 sliding down relative to the cover plate 48. Example 4

[0021] like Figures 1-3 As shown, at least three measuring rods 5 are arranged, and the bottom of the cylinder 47 is fixedly connected to the elastic membrane 56; the soil collapsibility under different measuring rods 5 may be different, and the sinking of all measuring rods 5 and the downward deformation of the elastic membrane 56 can form a three-dimensional structure of the settlement cavity model, which is convenient for the subsequent regional study of the soil, and the theoretical study of the influence of soil structure, component content and other factors on the settlement.

[0022] The test process of the present invention is as follows: the soil is placed in the rubber membrane cylinder 23, and after the soil is immersed in a set amount of water, the cylinder 45 lowers the cylinder 47 to the elastic membrane 56 to contact the soil surface, and the locking rod 55 fixing the measuring rod 5 is loosened. Under the action of gravity, the measuring rod 5 exerts a sinking force on the soil surface; Among them, the size and position of the force exerted on the soil surface to cause sinking can be conveniently adjusted through the present invention, and the restraining force on the side of the soil (simulating the lateral pressure exerted on the soil in an underground environment) can be conveniently adjusted, thereby facilitating theoretical research on the collapsibility of loess.

[0023] 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. An indoor physical model test system for studying the collapsibility of loess, comprising a base (1), wherein at least one sinking device is provided on the upper side of the base (1), wherein the sinking device comprises a cylindrical mold (2) and a loading device (4), wherein soil is contained in the cylindrical mold (2), and the loading device (4) applies a load to the soil through an opening on the upper side of the cylindrical mold (2), wherein: The cylindrical mold (2) comprises a support ring (21) and a bottom plate (22), and a cylindrical rubber membrane cylinder (23) is fixedly connected between the bottom plate (22) and the support ring (21); A plurality of guard plates (24) are provided in an annular array outside the rubber membrane cylinder (23), and the guard plates (24) are pulled outwards by a tensioning device (3); A sheet-shaped first pressure sensor is arranged at intervals on the inner cylinder wall of the rubber membrane cylinder (23).

2. The indoor physical model test system for loess collapsibility research according to claim 1 is characterized by: The guard plate (24) has an arc-shaped structure, one end of the guard plate (24) is rotatably connected to the base (1) via a rotating shaft, the tensioning device (3) comprises a drive ring (31), the rotating shaft of the guard plate (24) is fixedly connected to the first gear (32), the drive ring (31) is meshed with the first gear (32), and the drive ring (31) is rotatably connected to the upper side of the base (1); The driving ring (31) is driven to rotate by conventional power; The inner arc surface of the guard plate (24) and the outer wall of the rubber membrane cylinder (23) are evenly distributed and fixed with rubber columnar threads (33).

3. The indoor physical model test system for loess collapsibility research according to claim 2 is characterized by: The diameter of the rubber cylindrical wire (33) gradually decreases from a corner at one end of the upper side of the guard plate (24) away from the first gear (32) towards the first gear (32).

4. The indoor physical model test system for loess collapsibility research according to claim 1, characterized in that: The load device (4) comprises a vertical plate (41), the vertical plate (41) is fixedly connected to the upper side of the base (1), one side of the vertical plate (41) is fixedly connected to a support rod (42), the support rod (42) is fixedly connected to a support ring (21), a slide groove is provided on one side of the vertical plate (41), a slider (44) is slidably connected in the slide groove, the upper side of the vertical plate (41) is fixedly connected to a cylinder (45), and a telescopic rod of the cylinder (45) is fixedly connected to the slider (44); One side of the slider (44) is fixedly connected to a crossbar (46), the crossbar (46) is fixedly connected to a cylinder (47), the upper side of the cylinder (47) is fixedly connected to a cover plate (48), the cover plate (48) is provided with at least one through hole, a measuring rod (5) is slidably connected in the through hole, a scale line (51) is provided on the outer side of the measuring rod (5), a second pressure sensor (52) is fixedly connected to the bottom of the measuring rod (5), a placement hole is provided at the upper end of the measuring rod (5), a counterweight column (53) is provided in the placement hole.

5. The indoor physical model test system for loess collapsibility research according to claim 4, characterized in that: The cover plate (48) is fixedly connected to the side plate (54), the side plate (54) is arranged corresponding to the measuring rod (5), and the side plate (54) is threadedly connected to the locking rod (55).

6. The indoor physical model test system for loess collapsibility research according to claim 5, characterized in that: At least three measuring rods (5) are provided, and the bottom of the cylinder (47) is fixedly connected to an elastic membrane (56).

Images