WO2019015511A1

WO2019015511A1 - Flexible test device for studying three-dimensional soil arching effect and operation method

Info

Publication number: WO2019015511A1
Application number: PCT/CN2018/095162
Authority: WO
Inventors: 庄妍; 崔晓艳; 刘奂孜; 梁栋; 李嘉俊; 吴敏; 陶志威
Original assignee: 河海大学
Priority date: 2017-07-17
Filing date: 2018-07-10
Publication date: 2019-01-24
Also published as: CN107505196A; CN107505196B

Abstract

Provided are a flexible test device for studying a three-dimensional soil arching effect and an operation method. The device comprises a model frame (1), a sand storage container (7), and a plurality of auxiliary test devices, so as to ensure a test can be implemented and is accurate. The invention provides a distribution rule for vertical and horizontal stresses along an embankment according to the embankment height, such that it is possible to determine whether embankment filling materials are in an active or passive soil pressure state and to create a soil arch contour. The method changes the embankment height, pile spacing, and the size of a pile cap (3) in order to analyze a change in the stress states of the embankment, such that it is possible to study a three-dimensional soil arching effect generation mechanism in a pile-supported reinforced embankment. Placing a reinforcing body (6) at different heights of the embankment allows analysis of the use of the multi-layer reinforcing body (6) to enhance or impede the soil arching effect, so as to determine an effective reinforced area of the reinforcing body (6). Changing the position of colored sand facilitates observation of a settlement nephogram of the embankment filling materials in order to determine the size of deformations and the settlement trends of the embankment filling materials, thereby evaluating the vertical bearing capacity of soft soil in the pile-supported reinforced embankment.

Description

Three-dimensional soil arch effect research and test device and operation method capable of flexibly operating

Technical field

The invention relates to a test device for indoor model test research of highway and railway engineering, in particular to a three-dimensional soil arch effect research and test device and a method for operating the same in a pile-supported reinforced embankment.

Background technique

In the pile-supported embankment, since the strength of the pile is much larger than the strength of the soft soil, uneven settlement will occur in the embankment fill layer, which will promote the shear strain or the shear plane, resulting in the phenomenon of stress redistribution, from the embankment and The vertical stress of the upper load is redistributed, so that the vertical stress transmitted to the top of the pile increases, and the vertical stress transmitted to the soft soil decreases by an equal amount. This phenomenon of stress redistribution due to uneven settlement is Defined as the "earth arch effect." Hewlett & Randolph analyzed the soil arching effect through indoor model tests, pointing out that the shape of the plane earth arch is semi-circular, the shape of the space earth arch is hemispherical, the destruction of the soil arch only occurs at the pile cap and the vault, and the limit state is analyzed. At the two upper unit soils, two pile load sharing ratio expressions are obtained, and the small value is taken as the actual pile load sharing ratio. When there is no soil arching effect in the pile-supported embankment, all the soils are in the state of static earth pressure; when the soil arching effect occurs, the horizontal stress of the soil at the top of the arch gradually increases under the action of friction. At this time, the earth pressure coefficient will be greater than 1, and the soil at the vault is subjected to passive earth pressure. Under the limit condition, the soil is in a state of passive earth pressure failure; and the soil at the pile cap is in the vertical direction. Gradually increasing, the earth pressure coefficient is less than 1, and the soil at the pile cap is subjected to active earth pressure. Under the limit condition, the soil will be in the state of active earth pressure failure. Therefore, it is necessary to provide a research and test device, by which the vertical stress and horizontal stress above the pile cap and the soil body can be better studied, and the earth pressure coefficient of the soil body can be calculated, and then the limit balance method is used. It can be judged whether the soil is in the state of ultimate failure, so as to study the mechanism of the soil arching effect in the pile-supported reinforced embankment.

Summary of the invention

The object of the present invention is to provide a flexible three-dimensional soil arching effect research and test device and an operation method thereof, which can quickly and effectively layer and fill sand, lay colored sand, and accurately place earth pressure boxes and unload soil. By changing the embankment height, pile spacing and pile cap size, the variation of vertical and horizontal stress states in the embankment can be analyzed, and the distribution law of earth pressure coefficient can be calculated to study the mechanism of three-dimensional soil arching effect in pile-supported embankment. . The invention can study the effective reinforcement area of the reinforced body, and can also observe the settlement cloud diagram of the embankment filler by changing the position of the colored sand, judging the settlement deformation magnitude and the trend of the embankment filling, thereby evaluating the three-dimensional case, the soft soil is piled-type plus Vertical bearing capacity in the reinforced embankment.

In order to achieve the above object, the technical solution adopted by the present invention is:

A flexible three-dimensional soil arching effect research and test device, the test device mainly comprises a model trough, an embankment filling auxiliary device, a colored sand laying auxiliary device, an embankment filling upper plane leveling auxiliary device, and a earth pressure box mounting auxiliary device composition;

Wherein, the model groove is a cubic shape, wherein one side is a viewing surface made of a transparent material, and the left and right sides adjacent to the observation surface are respectively provided with a sand discharging port, and the sand discharging port is provided with a sand discharging gate. A test operation door is disposed on a rear side opposite to the observation surface, and the test operation door is formed by arranging a plurality of steel plate doors with handles arranged vertically, and the upper layer of the model groove is provided with sand for simulating the embankment filling. There are several earth pressure boxes in the sand, square piles in the lower layer, pile caps on the top of the square piles, square pile supports around the lower part of the piles, and the surrounding piles are filled to simulate the soft soil of the foundation. Foam particles, and a sand barrier layer between the upper layer and the lower layer for preventing the embankment filler from leaking into the simulated foundation soft soil;

The model tank is externally connected with a sand storage box, and the sand storage box surrounds the left side, the right side and the rear side of the model tank, and a cover plate is arranged above the sand storage box;

The embankment filling auxiliary device comprises a plane frame with a spiral track and a filling funnel which can be placed on the track and moves along the track, and the filling funnel is provided with a switch valve for controlling the falling speed of the sand, and filling There is a roller on the funnel, the roller can move along the spiral track, and the plane frame can be movable on the model groove;

The colored sand laying auxiliary device comprises a linear track beam and a laying funnel which can be placed on the track, and the colored sand can be placed in the laying funnel, the roller is arranged on the outer circumference of the laying funnel, the roller can move on the linear track, and the funnel is laid. There is a switch valve for controlling the falling speed of the colored sand, and the linear track beam can be movable on the model slot;

The plane leveling auxiliary device on the embankment fill comprises a square grille net, a height control column, a vertically intersecting overlapping beam and a horizontal ruler, wherein the lower end of the height control column is fixedly connected with the square grille net, and the height control column and the height control column The plane of the square grille is vertical, the height control column is movably connected with the lap beam, and the height control column can move up and down along the vertical direction, the level ruler is fixed on the square grid net, and the lap beam can be moved on the model slot;

The earth pressure box mounting auxiliary device is composed of two movable overlapping beams and a laser projector which are perpendicular to each other and can be moved back and forth, and the laser projector is disposed at the intersection of the two beams, and the emission port of the laser projector is vertical Down, the movable lap beam can be mounted on the model slot.

The earth pressure box is placed at a position where a horizontal and vertical earth pressure box is placed at a height above the pile and above the soft soil to measure the vertical and horizontal stress of the embankment along with the height of the embankment, This calculates the earth pressure coefficient to determine whether the soil at different locations in the embankment is in an active or passive earth pressure state. According to Hewlett & Randolph theory (the soil at the vault is in a state of passive earth pressure, the soil at the pile cap is in the state of active earth pressure, and the shape of the arch is hemispherical in three dimensions), and the soil arch contour is made in combination with the test results. By changing the height of embankment, the spacing of piles and the size of pile caps, the variation of stress state in embankment is analyzed, and the mechanism of three-dimensional soil arching effect in pile-supported embankment is not produced, partially produced and completely generated. The criterion is: when the vertical stress measurement in the embankment and the straight line γh (γ is the gravity of the embankment; h is the filling height of the embankment), the soil arching effect is not generated; when the vertical stress measurement in the embankment is in a straight line Below the γh, and when there is differential settlement on the embankment fill surface, the soil arch is generated; when the vertical stress measurement in the embankment is below the straight line γh, and the isosurface is observed in the embankment filling, the soil arch is completely produce.

The utility model further comprises at least one reinforcing body, wherein the left and right sides and the rear side of each of the reinforcing bodies are respectively provided with a steel frame with a hole, and the boundary of the reinforcing body is fixed in the hole of the steel frame, and the steel frame passes The fixing frame is fixed on the inner wall of the model groove, and the reinforcing body is located above the sand blocking layer, and a plurality of strain gauges are evenly arranged on the surface thereof.

The reinforced body is placed at different heights of the embankment, and the variation of the pile-soil stress ratio under different working conditions is analyzed. The influence of the multi-layer reinforced body on the soil arching effect is promoted or suppressed, and the effective reinforcement area of the reinforced body is determined. . The colored sand is layered at different heights of the embankment, and the settlement cloud map of the embankment filling is observed through the change of the position of the colored sand, thereby judging the settlement deformation trend and trend of the embankment filling, and thereby calculating the three-dimensional case, the soft soil is in the pile-supporting type. Vertical bearing capacity in reinforced embankments.

The sand simulation embankment filler is covered with colored sand on the side of the observation surface.

The observation surface is made of tempered tempered glass.

A scale is arranged inside and outside the edge of the model groove and the sand storage box.

The invention provides a method for operating a three-dimensional earth arch effect research and test device which can be flexibly operated, and the method comprises the following steps:

(1) Place the model tank on a horizontal site, clean the tank, apply Vaseline on the inner wall of the observation surface, and lay a PVC film on the inner wall of the other three sides. According to the specific requirements of the test, set the embankment height, pile spacing, and pile position. , the size of the pile cap, the arrangement position of the earth pressure box;

(2) Fixing the pile body and the pile cap, and filling the foam particles for simulating the soft soil of the foundation around the pile body, and arranging the sand barrier layer;

(3) Arrange the earth pressure box: install the earth pressure box to install the auxiliary device on the model slot, determine the lateral and longitudinal position of the earth pressure box according to the specific requirements of the test, fix the position of the laser emitter, and shoot the laser on the upper surface of the bottom layer. The precise arrangement of the earth pressure box, the earth pressure box and the data acquisition instrument are connected to collect the earth pressure data;

(4) Filling the sand: The embankment filling auxiliary device is placed on the model trough, and then the sand is filled in the filling funnel, and the funnel is moved on the spiral track to fill the sand;

(5) Plane leveling on the embankment fill: After the sand fill is completed, the embankment filling auxiliary device is removed, and then the plane leveling auxiliary device on the embankment fill is set on the model trough to adjust the height of the square grille net. Up to the height of the filling, by observing the height difference and level of the plane on the fill and the square grille, leveling with a brush;

(6) Laying colored sand: After the sand leveling is completed, remove the plane leveling auxiliary device on the embankment filling, install the colored sand laying auxiliary device on the model trough, add colored sand to the laying funnel, and bring the linear track close to The observation surface of the model groove moves the moving funnel on the linear track to lay the colored sand on the upper surface of the sand near the observation surface;

(7) Repeat the steps of arranging the earth pressure box, filling the sand, leveling the plane on the embankment, and laying the colored sand according to the specific test requirements;

(8) After the embankment is completed, use a digital camera to capture the color sand position displayed on the front tempered glass at this time, and let it stand for more than 24 hours;

(9) After the completion of the positioning, the data collection is ended, and the color sand position displayed by the front tempered glass at this time is photographed by a digital camera;

(10) Open the sand discharge port, let the sand discharge into the surrounding sand storage box with gravity, collect the earth pressure box, and clean the model tank.

The invention also provides a method for operating a flexible three-dimensional soil arching research and test device, the method comprising the following steps:

(1) Place the model tank on a horizontal site, clean the tank, apply Vaseline on the inner wall of the observation surface, and lay a PVC film on the inner wall of the other three sides. According to the specific requirements of the test, set the embankment height, pile spacing, and pile position. , the size of the pile cap, the height of the reinforced body, and the arrangement position of the earth pressure box;

(4) Arranging the reinforced body: fixing the reinforced body and the perforated steel frame according to the specific conditions of the test;

(5) Filling the sand: The embankment filling auxiliary device is placed on the model trough, and then the sand is filled in the filling funnel, and the funnel is moved on the spiral track to fill the sand;

(6) Plane leveling on embankment fill: After the sand fill is completed, the embankment filling auxiliary device is removed, and then the plane leveling auxiliary device on the embankment fill is set on the model trough to adjust the height of the square grille net. Up to the height of the filling, by observing the height difference and level of the plane on the fill and the square grille, leveling with a brush;

(7) Laying colored sand: After the sand leveling is completed, remove the plane leveling auxiliary device on the embankment filling, install the colored sand laying auxiliary device on the model trough, add colored sand to the laying funnel, and bring the linear track close to The observation surface of the model groove moves the moving funnel on the linear track to lay the colored sand on the upper surface of the sand near the observation surface;

(8) Repeat the steps of arranging the earth pressure box, filling the sand, leveling the plane on the embankment, and laying the colored sand according to the specific test requirements;

(9) After the embankment is completed, use a digital camera to capture the position of the colored sand displayed on the front tempered glass at this time, and let it stand for more than 24 hours;

(10) After the completion of the positioning, the data collection is ended, and the color sand position displayed by the front tempered glass at this time is photographed by a digital camera;

(11) Open the sand discharge port, let the sand discharge into the surrounding sand storage box with gravity, collect the earth pressure box, and clean the model tank.

In step (4), according to the specific conditions of the test, when multiple layers of reinforcing ribs need to be arranged, the first layer of the first layer of reinforcing ribs and the perforated steel frame are first fixed, and the flat surface of the filled sand and embankment is leveled. Then arrange the second layer of ribs, and so on, until the top layer of ribs is placed.

In the step (4), according to the specific conditions of the test, the earth pressure box and the colored sand are arranged in the sand between the adjacent reinforcing ribs.

Advantageous Effects: The test device provided by the invention can quickly and effectively layer and fill sand, lay colored sand, place earth pressure box and unload soil; can reveal the distribution law of vertical and horizontal stress along the embankment height in the embankment Therefore, it is judged that the embankment packing is in an active or passive earth pressure state, and a soil arch contour is formed. By changing the height of embankment, the spacing of piles and the size of pile caps, the variation of stress state in embankment is analyzed, and the mechanism of three-dimensional soil arching effect in pile-supported embankment is studied. The reinforced body is placed at different heights of the embankment, and the multi-layer reinforced body is analyzed to promote or inhibit the soil arching effect to determine the effective reinforcement area of the reinforced body. Observing the settlement cloud map of embankment filling by changing the position of colored sand, judging the settlement deformation trend and trend of embankment filling, and evaluating the vertical bearing capacity of soft soil in pile-supported embankment.

DRAWINGS

Figure 1 is a top view of a three-dimensional soil arching effect test device;

Figure 2 is a cross-sectional view of a three-dimensional soil arching effect test device;

Figure 3 is a schematic view showing the structure of a square pile, a pile cap and a square pile support;

Figure 4 is a schematic view showing the structure inside the model groove;

Figure 5 is a plan view of the embankment filling auxiliary device;

Figure 6 is a schematic structural view of an embankment filling auxiliary device;

7 is a schematic structural view of a plane leveling auxiliary device on an embankment fill;

Figure 8 is a schematic structural view of an earth pressure box mounting auxiliary device;

9 is a schematic structural view of a color sand laying auxiliary device;

1 is a model trough, 2 is a square pile, 3 is a pile cap, 4 is a square pile support, 5 is a foam particle, 6 is a reinforced body, 7 is a sand storage box, 8 is a sand discharge port, and 9 is a sand discharge port. Gate gate, 10 is earth pressure box, 11 is tempered glass, 12 is strain gauge, 13 is sand barrier, 14 is steel slot, 15 is steel frame, 16 is fixed frame, 17 is handle, 18 is test operation Door, 19 is a filling funnel, 20 is a plane frame with a spiral track, 21 is a lap beam, 22 is a square grid, 23 is a height control column, 24 is a level ruler, 25 is a laser projector, 26 is The movable overlapping beam, 27 is a linear track beam, and 28 is a laying funnel.

Detailed ways

The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The scope of protection of the present invention is not limited to the specific embodiments, but is defined by the claims.

Example 1

A flexible three-dimensional soil arching effect research and test device, the test device is mainly composed of a model tank 1, an embankment filling auxiliary device, a colored sand laying auxiliary device, an embankment filling plane flat leveling auxiliary device, and an earth pressure box installation auxiliary device. Device composition

As shown in Figures 1, 2, and 4, the model groove 1 is of a cubic type, one side of which is a viewing surface made of a transparent material, and the observation surface can be made of tempered glass 11, and can be made by steel slots on both sides. fixed. The left and right sides adjacent to the observation surface are respectively provided with two sand discharge ports 8 at the three equal points on the horizontal line at a distance of 800 mm from the upper edge, and the sand discharge port 8 is long in length and width is 100 mm, and the sand is discharged. There are slots on the left side, the right side, and the lower side of the port 8, and a steel plate with a handle can be inserted as the sand vent gate 9, and the slit is sealed with a rubber strip. A test operation door 18 is disposed on the rear side opposite to the observation surface, and the test operation door 18 is formed by arranging seven steel plate doors with handles having a height of 100 mm and a length of 600 mm from top to bottom, corresponding to the model groove. The height and length of the rear door frame are 700mm and 600mm respectively. There are slots on the left side, right side and lower side of the door frame, and the gap is sealed with rubber strips. At the beginning of the test, the lowermost (first layer) test operation door is closed, the other layer test operation doors are opened, and the auxiliary device is used to fill and level the sand, lay the colored sand, and place the earth pressure box. The two-layer test operation door is closed, and so on, the operation door is gradually closed from the lower layer to the upper layer. This process can quickly and efficiently complete the stratified uniform filling of the embankment filling and the placement of the earth pressure box.

The upper layer of the model tank 1 is placed with sand for simulating the embankment filling, and a plurality of earth pressure boxes are arranged in the sand, and the square pile 2 is placed in the lower layer. As shown in FIG. 3, the pile cap 3 is arranged on the top of the square pile 2, A square pile support 4 is arranged around the lower part of the square pile 2, and soft and rigid polypropylene foam particle 5 having a size of 1 cm ³ for simulating the foundation soft soil is filled around the pile of the square pile 2, and between the upper layer and the lower layer a sand barrier layer 13 for preventing leakage of the embankment filler into the simulated foundation soft soil;

As shown in Figures 1, 2, and 4, the outside of the model tank 1 is connected to the sand storage box 7 by welding, and the sand filled in the model tank can be quickly unloaded into the sand storage box through the sand discharge port when the test is completed. The sand storage box 7 surrounds the left side, the right side and the rear side of the model tank 1, and the outer boundary of the sand storage box 7 is separated from the inner boundary by 500 mm, and a cover plate is arranged above the sand storage box 7; the model tank 1 and the sand storage box 7 are edged. There is a scale with a minimum scale of 1mm inside and outside.

As shown in Figures 5 and 6, the embankment filling assisting device comprises a plane frame 20 with a spiral track and a filling funnel 19 which can be placed on the track and moved along the track, and the sand can be placed in the funnel to fill the funnel. There is a switch valve for controlling the falling speed of the sand. The filling funnel 19 has rollers on the spiral type track, and the filling process is carried out with the movement, so that the filling can be well controlled. The plane frame 20 can be mounted on the model slot 1 and can be detached;

As shown in Fig. 9, the colored sand laying auxiliary device comprises a linear track beam 27 and a laying funnel 28 which can be placed on the track. The laying funnel can be placed with colored sand, the laying funnel has rollers on the outer circumference, and the roller can be in a straight line. Moving on the track, the leakage of the laying funnel can be placed directly above the required laying position. During the movement of the funnel, the colored sand can be leaked into the designated position through the laying funnel, and the laying funnel is provided with the falling speed of controlling the colored sand. The switch valve, the linear track beam 27 can be mounted on the model slot 1 and can be detached;

As shown in FIG. 7, the plane leveling auxiliary device on the embankment fill includes a square grille net 22, a height control column 23, a vertically intersecting overlapping beam 21 and a horizontal ruler 24, wherein the lower end of the height control column 23 and the square grille The net 22 is welded, and the height control column 23 is perpendicular to the plane of the square grille net 22, the height control column 23 is movably connected to the overlapping beam 21, and the height control column 23 is movable up and down in the vertical direction, and the level 24 is fixed in the square. On the grille net 22, the lap beam 21 can be placed on the model slot 1 and can be detached; the height control column can be moved up and down by the pulley, fixed at different height positions, and the level ruler is fixed on the grid net, and the upper surface of the fill is observed. And the relative height and level of the plane of the grille to determine whether the surface of the fill is horizontal, and a small brush can be used to assist in leveling the upper surface of the fill. By fixing the planar grille mesh at different heights, the height of the upper surface of the fill soil is controlled, and the height difference at different positions of the plane fill is intuitively sensed, and the flattening is carried out in a targeted manner.

As shown in FIG. 8, the earth pressure box mounting auxiliary device is composed of two movable overlapping beams 26 and a laser projector 25 which are perpendicular to each other and can be moved back and forth, and the laser projector is disposed at the intersection of the two beams, and the laser projection The launching port of the device is vertically downward, and the movable overlapping beam 26 is movable on the model slot 1. After setting the position of the earth pressure box, according to the scale of each side of the model groove, two beams can be fixed at the position above the groove wall. The laser projector can be placed at the intersection of the two beams, and then vertically according to the laser projector. Projected on the surface of the fill surface to accurately determine where the earth pressure box should be placed.

The specific steps of the operation method of the three-dimensional soil arching effect research and test device (excluding the rib) in this embodiment are as follows:

(1) Place the model tank 1 on a horizontal site, clean the tank, apply Vaseline on the inner wall of the tempered glass 11, and lay a PVC film on the inner wall of the other three sides to reduce the influence of the side wall friction of the model groove. According to the specific requirements of the test, set the embankment height, pile spacing, pile position, pile cap size, arranging height of the reinforced body, and the arrangement position of the earth pressure box;

(2) Square piles with length, width and height of 50mm×50mm×400mm with square pile support are placed according to the specific design position. In order to fix the pile body, the adjacent piles at the bottom of the model groove can be laid 100mm thick. The dense dry sand can be installed after the pile is fixed. A 300mm thick soft and rigid polypropylene foam foam particle of 1cm ³ is used to simulate the foundation soft soil around the pile body. A layer of low strength is laid at the location of the pile cap 3 and the surface of the simulated foundation soft soil. Separate the sand layer (to avoid affecting the test results), prevent the embankment packing from leaking into the simulated foundation soft soil;

(3) Arrange the earth pressure box: install the earth pressure box to install the auxiliary device on the model slot, determine the lateral and longitudinal position of the earth pressure box according to the specific requirements of the test, fix the position of the laser emitter, and shoot the laser on the upper surface of the bottom layer. The soil pressure box is accurately arranged on the surface of the soft soil and above the pile cap. The earth pressure box 10 is placed according to the laser projection position, and the horizontal pressure and vertical stress at different positions of the soil are measured by the earth pressure box 10, the earth pressure box and the data. Collecting instrument connection to collect earth pressure data;

(4) Filling the sand: The embankment filling auxiliary device is placed on the model trough, then the sand is filled in the filling funnel, the filling funnel 19 is opened, and the filling funnel 19 is placed in the spiral orbital plane frame. 20 moves along the track, and the sand is evenly filled on the top of the pile beam and the top of the foam. During the filling process, 50 mm is used as a layer to fill;

(6) Laying colored sand: After the sand leveling is completed, remove the plane leveling auxiliary device on the embankment filling, install the colored sand laying auxiliary device on the model trough, add colored sand to the laying funnel, and bring the linear track close to Observing the surface of the model groove, moving the moving funnel on the linear track, laying a thin layer of colored sand on the upper surface of the sand near the tempered glass 11; observing the settlement cloud image of the embankment filling through the change of the position of the colored sand, the observation of the embankment can be visually observed Deformation mode of fill fill at different fill heights;

(9) After the completion of the positioning, the data collection is ended, and the position of the colored sand displayed by the front tempered glass is taken by the digital camera, and the data collected by the data acquisition instrument (the earth pressure, the horizontal earth pressure, the reinforced strain, etc.) are recorded. related data);

(10) After the test is finished, open the sand discharge port, let the sand discharge into the surrounding sand storage box with gravity, collect the earth pressure box, and clean the model tank.

By changing the height of the embankment, the spacing of the piles and the size of the pile caps, the vertical earth pressure and the horizontal earth pressure at different heights in the soft soil and the embankment above the pile cap are measured, and the settlement occurred at different positions in the embankment by means of colored sand. A curve of the vertical earth pressure along the height of the embankment can be made (the height of the embankment is the ordinate and the earth pressure is the abscissa). By comparing the relationship between the curve and the γh line, it can be judged whether the soil arching effect occurs: when the curve and When the γh line is close to coincidence, no soil arching effect occurs; when the curve falls below the γh line (indicating that the measured earth pressure value is less than the value of γh), and there is no equal subsidence surface in the embankment, the soil arching effect is partially generated; When the curve falls below the γh line and there is an equal surface in the embankment, the soil arching effect occurs completely. According to this condition, the quantitative relationship between the embankment height, the pile spacing, and the pile cap size can be judged when the soil arch is completely not generated, partially generated, or completely generated. At the same time, according to the vertical earth pressure and the horizontal earth pressure at different heights in the measured embankment, the distribution law of earth pressure coefficient with embankment height can be obtained (earth pressure coefficient=horizontal earth pressure/vertical earth pressure). The earth pressure coefficient will increase first and then decrease along the embankment depth, and the earth pressure coefficient will increase from the sudden change to the decrease, which is the height of the inner arch of the soil arch, so that the effect of soil arching can be analyzed. region.

In summary, the present invention obtains the strain and vertical deformation of the reinforced body by changing the strength and arrangement of the reinforced body, the strength of the soft soil of the foundation, the settlement of the soft soil and the vertical stress and horizontal direction of the embankment filler under different conditions. The distribution of earth pressure, thereby analyzing the effect of the multi-layered reinforcement on the soil arching effect, and determining the effective reinforcement area of the reinforced body. Through the measurement of the soft soil settlement, the vertical bearing capacity of the soft soil in the pile-supported reinforced embankment is calculated.

Example 2

The upper layer of the model tank 1 is placed with sand for simulating the embankment filling, and a plurality of earth pressure boxes are arranged in the sand, and the square pile 2 is placed in the lower layer. As shown in FIG. 3, the pile cap 3 is arranged on the top of the square pile 2, A square pile support 4 is arranged around the lower part of the square pile 2, and foam particles 5 for simulating the soft soil of the foundation are filled around the pile of the square pile 2, and between the upper layer and the lower layer, the embankment filler is prevented from leaking into the simulated foundation soft soil. Sand barrier layer 13;

For the test considering the reinforced body, the left and right sides and the rear side of the reinforced body 6 are respectively provided with a steel frame 15 with a hole, and the boundary of the reinforced body 6 is fixed in the hole of the steel frame 15, and the steel frame 15 passes through the fixing frame 16 is fixed on the inner wall of the model groove 1, and the reinforced body 6 is located above the sand barrier layer 13, and a plurality of strain gauges 12 are uniformly disposed on the surface thereof. For the single-layer reinforced test, the reinforced body 6 is arranged 20 mm above the pile cap 3; for the two-layer reinforced body 6, each layer of the reinforced body 6 is respectively arranged at the top of the square pile 2 at 20 mm, 50 mm; The layer reinforced body 6 is arranged at 20 mm, 50 mm, and 100 mm above the top of the square pile 2, and the strain gauge 12 is attached to the reinforced body 6 according to design requirements.

The specific steps of the operation method of the three-dimensional soil arching effect research and test device (including the rib) in this embodiment are as follows:

(3) Arrange the earth pressure box: install the earth pressure box to install the auxiliary device on the model slot, determine the lateral and longitudinal position of the earth pressure box according to the specific requirements of the test, fix the position of the laser emitter, and shoot the laser on the upper surface of the bottom layer. The precise arrangement of the earth pressure box is to place the earth pressure box 10 according to the laser projection position, and the earth pressure box 10 is used to measure the horizontal and vertical stresses at different positions of the soil body, and the earth pressure box is connected with the data collecting instrument to collect the earth pressure data;

(4) Arranging the reinforced body: According to the specific conditions of the test, the reinforced body and the perforated steel frame are fixed; for the single layer reinforced test, the reinforced body 6 is arranged 20 mm above the pile cap 3; The rib body 6, each layer of the reinforced body 6 is arranged at 20 mm and 50 mm above the top of the square pile 2; for the three-layer reinforced body 6, each layer of reinforced 6 bodies is respectively arranged above the top of the square pile 2 20 mm, 50 mm, 100 mm At the rib body 6, the strain gauge 12 is attached according to the design requirements. When arranging the multi-layer ribs, first fix the first reinforced ribs at the bottom and the steel frame with holes, fill the sand and embankment, level the plane on the embankment, arrange the second layer of ribs, and so on. Until the top layer of ribs is placed. According to the specific conditions of the test, the earth pressure box and the position near the observation surface can be laid in the sand between the adjacent reinforcing ribs.

(5) Filling the sand: The embankment filling auxiliary device is placed on the model trough, then the sand is filled in the filling funnel, the filling funnel 19 switch is opened, and the filling funnel 19 is placed in the spiral orbital plane frame. 20 moves along the track, and the sand is evenly filled on the top of the pile beam and the top of the foam. During the filling process, 50 mm is used as a layer to fill;

(7) Laying colored sand: After the sand leveling is completed, remove the plane leveling auxiliary device on the embankment filling, install the colored sand laying auxiliary device on the model trough, add colored sand to the laying funnel, and bring the linear track close to Observing the surface of the model groove, moving the moving funnel on the linear track, laying a thin layer of colored sand on the upper surface of the sand near the tempered glass 11; observing the settlement cloud image of the embankment filling through the change of the position of the colored sand, the observation of the embankment can be visually observed Deformation mode of fill fill at different fill heights;

(10) After the completion of the positioning, the data collection is ended, and the position of the colored sand displayed by the front tempered glass at this time is photographed by a digital camera, and the data collected by the data acquisition instrument (the earth pressure, the horizontal earth pressure, the reinforced strain, etc.) are recorded. related data);

(11) After the test is finished, open the sand discharge port, let the sand discharge into the surrounding sand storage box with gravity, collect the earth pressure box, and clean the model tank.

Claims

A flexible three-dimensional earth arch effect research and test device, characterized in that: the test device mainly comprises a model trough (1), an embankment filling auxiliary device, a colored sand laying auxiliary device, an embankment filling upper plane leveling auxiliary device, And an earth pressure box mounting auxiliary device;

Wherein, the model groove (1) has a cubic shape, wherein one side is a viewing surface made of a transparent material, and the left and right sides adjacent to the observation surface are respectively provided with a sand discharging opening (8), and the sand discharging opening ( 8) There is a sand discharge gate (9), and a test operation door (18) is arranged on the rear side opposite to the observation surface, and the test operation door (18) is a multi-layer steel plate door with a handle arranged up and down. Forming, the upper layer of the model tank (1) is placed with sand for simulating the embankment filling, and a plurality of earth pressure boxes are arranged in the sand, and the square pile (2) is placed on the lower layer, and the top end of the square pile (2) is provided. The pile cap (3) and the square pile support (4) are arranged around the lower part of the square pile (2). The square pile (2) is filled with foam particles (5) for simulating the foundation soft soil, and the upper layer and the lower layer are filled. There is a sand barrier layer (13) for preventing sand leakage from simulating embankment filling into simulated soft soil;

The model tank (1) is externally connected with a sand storage box (7), and the sand storage box (7) surrounds the outer left side, the right side and the rear side of the model tank (1), and a cover plate is arranged above the sand storage box (7);

The embankment filling auxiliary device comprises a plane frame (20) with a spiral track and a filling funnel (19) which can be placed on the track and moved along the track, and the filling funnel (19) is provided with control sand The falling speed of the opening and closing valve, the filling funnel (19) has a roller, the roller can move along the spiral track, and the plane frame (20) can be movably mounted on the model groove (1);

The colored sand laying auxiliary device comprises a linear track beam (27) and a laying funnel (28) which can be placed on the track. The laying funnel can be placed with colored sand, the laying funnel has a roller on the outer circumference, and the roller can be in a straight line. Moving on the track, the laying funnel is provided with a switching valve for controlling the falling speed of the colored sand, and the linear track beam (27) can be movable on the model groove (1);

The plane leveling auxiliary device on the embankment fill comprises a square grille net (22), a height control column (23), a vertically intersecting overlapping beam (21) and a level ruler (24), wherein the height control column (23) The lower end is fixedly connected to the square grille net (22), and the height control column (23) is perpendicular to the plane of the square grille net (22), and the height control column (23) is movably connected to the overlapping beam (21), and the height is The control column (23) can be moved up and down in a vertical direction, the horizontal ruler (24) is fixed on the square grille net (22), and the overlapping beam (21) can be moved on the model slot (1);

The earth pressure box mounting auxiliary device is composed of two movable overlapping beams (26) and a laser projector (25) which are perpendicular to each other and can be moved back and forth, and the laser projector is disposed at the intersection of the two beams, and the laser projection The launching port of the device is vertically downward, and the movable overlapping beam (26) is movable on the model groove (1).
A flexible three-dimensional soil arching effect research and test apparatus according to claim 1, further comprising at least one layer of reinforced body (6), said left and right sides of said reinforced body (6) And the rear side is respectively provided with a steel frame (15) with a hole, and the boundary of the reinforced body (6) is fixed in the hole of the steel frame (15), and the steel frame (15) is fixed by the fixing frame (16) On the inner wall of the model tank (1), the reinforced body (6) is located above the sand barrier layer (13), and a plurality of strain gauges (12) are uniformly disposed on the surface thereof.
The invention relates to a flexible operation three-dimensional soil arching effect research and test device according to claim 1, wherein the sand simulation embankment filler is covered with colored sand on a side close to the observation surface.
A flexible three-dimensional earth arch effect research and test device according to claim 1, wherein the observation surface is made of tempered glass (11).
The invention relates to a flexible operation three-dimensional soil arching effect research and test device according to claim 1, characterized in that: the model groove (1) and the sand storage box (7) are provided with scales inside and outside the edge of the sand storage box (7).
The method for operating a flexible three-dimensional earth arch effect research and test device according to claim 1, wherein the method comprises the following steps:

(1) Place the model tank on a horizontal site, clean the tank, apply Vaseline on the inner wall of the observation surface, and lay a PVC film on the inner wall of the other three sides. According to the specific requirements of the test, set the embankment height, pile spacing, and pile position. , the size of the pile cap, the arrangement position of the earth pressure box;

(2) Fixing the pile body and the pile cap, and filling the foam particles for simulating the soft soil of the foundation around the pile body, and arranging the sand barrier layer;

(3) Arrange the earth pressure box: install the earth pressure box to install the auxiliary device on the model slot, determine the lateral and longitudinal position of the earth pressure box according to the specific requirements of the test, fix the position of the laser emitter, and shoot the laser on the upper surface of the bottom layer. The precise arrangement of the earth pressure box, the earth pressure box and the data acquisition instrument are connected to collect the earth pressure data;

(4) Filling the sand: The embankment filling auxiliary device is placed on the model trough, and then the sand is filled in the filling funnel, and the funnel is moved on the spiral track to fill the sand;

(5) Plane leveling on the embankment fill: After the sand fill is completed, the embankment filling auxiliary device is removed, and then the plane leveling auxiliary device on the embankment fill is set on the model trough to adjust the height of the square grille net. Up to the height of the filling, by observing the height difference and level of the plane on the fill and the square grille, leveling with a brush;

(6) Laying colored sand: After the sand leveling is completed, remove the plane leveling auxiliary device on the embankment filling, install the colored sand laying auxiliary device on the model trough, add colored sand to the laying funnel, and bring the linear track close to The observation surface of the model groove moves the moving funnel on the linear track to lay the colored sand on the upper surface of the sand near the observation surface;

(7) Repeat the steps of arranging the earth pressure box, filling the sand, leveling the plane on the embankment, and laying the colored sand according to the specific test requirements;

(8) After the embankment is completed, use a digital camera to capture the color sand position displayed on the front tempered glass at this time, and let it stand for more than 24 hours;

(9) After the completion of the positioning, the data collection is ended, and the color sand position displayed by the front tempered glass at this time is photographed by a digital camera;

(10) Open the sand discharge port, let the sand discharge into the surrounding sand storage box with gravity, collect the earth pressure box, and clean the model tank.
The method for operating a flexible three-dimensional earth arch effect research and test device according to claim 1, wherein the method comprises the following steps:

(1) Place the model tank on a horizontal site, clean the tank, apply Vaseline on the inner wall of the observation surface, and lay a PVC film on the inner wall of the other three sides. According to the specific requirements of the test, set the embankment height, pile spacing, and pile position. , the size of the pile cap, the number and arrangement height of the reinforced body, and the arrangement position of the earth pressure box;

(2) Fixing the pile body and the pile cap, and filling the foam particles for simulating the soft soil of the foundation around the pile body, and arranging the sand barrier layer;

(3) Arrange the earth pressure box: install the earth pressure box to install the auxiliary device on the model slot, determine the lateral and longitudinal position of the earth pressure box according to the specific requirements of the test, fix the position of the laser emitter, and shoot the laser on the upper surface of the bottom layer. The precise arrangement of the earth pressure box, the earth pressure box and the data acquisition instrument are connected to collect the earth pressure data;

(4) Arranging the reinforced body: fixing the reinforced body and the perforated steel frame;

(5) Filling the sand: The embankment filling auxiliary device is placed on the model trough, and then the sand is filled in the filling funnel, and the funnel is moved on the spiral track to fill the sand;

(6) Plane leveling on embankment fill: After the sand fill is completed, the embankment filling auxiliary device is removed, and then the plane leveling auxiliary device on the embankment fill is set on the model trough to adjust the height of the square grille net. Up to the height of the filling, by observing the height difference and level of the plane on the fill and the square grille, leveling with a brush;

(7) Laying colored sand: After the sand leveling is completed, remove the plane leveling auxiliary device on the embankment filling, install the colored sand laying auxiliary device on the model trough, add colored sand to the laying funnel, and bring the linear track close to The observation surface of the model groove moves the moving funnel on the linear track to lay the colored sand on the upper surface of the sand near the observation surface;

(8) Repeat the steps of arranging the earth pressure box, filling the sand, leveling the plane on the embankment, and laying the colored sand according to the specific test requirements;

(9) After the embankment is completed, use a digital camera to capture the position of the colored sand displayed on the front tempered glass at this time, and let it stand for more than 24 hours;

(10) After the completion of the positioning, the data collection is ended, and the color sand position displayed by the front tempered glass at this time is photographed by a digital camera;

(11) Open the sand discharge port, let the sand discharge into the surrounding sand storage box with gravity, collect the earth pressure box, and clean the model tank.
The method for operating a flexible three-dimensional soil arching research and test device according to claim 7, wherein in the step (4), according to the specific conditions of the test, it is necessary to arrange a plurality of reinforcing ribs, firstly After the first layer of reinforcing ribs and the perforated steel frame are fixed, the sand and the embankment are filled with the flat surface, and then the second layer of reinforcing ribs is arranged, and so on, until the uppermost layer of reinforcing ribs is arranged.
The method for operating a flexible three-dimensional soil arching research and test device according to claim 8, wherein in step (4), sand is between adjacent reinforcing ribs according to specific conditions of the test. The earth pressure box and the colored sand are arranged inside.