A device and method for preparing sand and clay interbedded soil

Abstract

The application provides a sand and clay interbedded soil preparation device and method, and relates to the field of geotechnical centrifugal testing. The sand and clay interbeded soil preparation device comprises a drum centrifuge and a plurality of model boxes. The drum centrifuge is provided with a rotating cylinder, and the plurality of model boxes are circumferentially and spacedly arranged in the interior of the rotating cylinder. The model box is further provided with a water-permeable barrier layer, a test soil sample and a drainage pipeline. The model box is provided with a sample loading port on the side facing the center of the rotating cylinder. The water-permeable barrier layer is arranged on the inner side of the model box, and the test soil sample is filled in the interior of the water-permeable barrier layer. The test soil sample comprises at least two clay layers and a sand layer between the two clay layers. The layers of the at least two clay layers and the sand layer are all arranged perpendicularly to the radial direction of the rotating cylinder. The drainage pipeline is arranged between the model box and the water-permeable barrier layer. The drainage pipeline has a water inlet and a drainage outlet. The water inlet of the drainage pipeline is located in the interior of the model box, and the drainage outlet of the drainage pipeline extends to the outside of the sample loading port.

Description

Technical Field

[0001] This invention relates to the field of geotechnical centrifuge testing technology, and in particular to a preparation apparatus and method for sand-clay interlayered soil. Background Technology

[0002] In marine geotechnical engineering, the properties of soil are mainly determined by its in-situ stress level. Due to the anisotropic and nonlinear characteristics of soil materials, conventional geotechnical model tests under one times gravity acceleration are difficult to reproduce the in-situ stress level of the soil, and the test results are prone to distortion.

[0003] Existing geotechnical centrifuge model tests involve placing a scaled-down geotechnical model in a high-speed rotating centrifuge. The centrifugal inertial frame compensates for the model's weight loss due to the scaling effect, thus simulating the true level of in-situ stress in the soil. In recent years, geotechnical centrifuge model testing technology has been widely used to solve complex geotechnical engineering problems. The drum centrifuge is one of the implementation devices for geotechnical centrifuge model tests, using the centrifugal force generated by high-speed rotation to provide the geotechnical model with hypergravity acceleration. In actual marine engineering, the common distribution of seabed strata is interbedded sand and clay. However, the sand in existing geotechnical centrifuge models is cohesive-free soil with poor self-supporting properties under saturation, making it prone to collapse during centrifugation tests, resulting in poor-quality sand samples.

[0004] Therefore, existing geotechnical centrifuge model tests cannot realistically simulate the in-situ stress level of seabed soil layers, cannot guarantee the forming effect of seabed strata geotechnical models, and the accuracy of subsequent test results is low. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a preparation apparatus and method for sand-clay interbedded soil, thereby solving the problems that existing geotechnical centrifugal model tests cannot realistically simulate the in-situ stress level of seabed soil layers, cannot guarantee the forming effect of seabed strata geotechnical models, and result in low accuracy of subsequent test results.

[0006] The technical solution of the apparatus for preparing sand-clay interbedded soil of the present invention is as follows:

[0007] The apparatus for preparing sandy-clay interbedded soil includes a drum centrifuge and multiple model boxes. The drum centrifuge is equipped with a rotating cylinder, and the multiple model boxes are circumferentially spaced inside the rotating cylinder.

[0008] The model box is also equipped with a permeable barrier layer, a test soil sample and a drainage pipe. The model box has a sample loading port on the side facing the center of the rotating cylinder. The permeable barrier layer is set inside the model box, and the test soil sample is filled inside the permeable barrier layer.

[0009] The test soil sample includes at least two clay layers and a sand layer between the two clay layers, and the layers of the at least two clay layers and the sand layer are arranged perpendicular to the radial direction of the rotating cylinder;

[0010] The drainage pipe is disposed between the model box and the water-permeable barrier layer. The drainage pipe has an inlet and an outlet. The inlet of the drainage pipe is located inside the model box, and the outlet of the drainage pipe extends to the outside of the sample loading port.

[0011] Furthermore, the model box is rectangular in shape, and includes a back plate and four side plates fixedly connected to the back plate. The back plate of the model box is attached to the wall of the rotating cylinder.

[0012] Furthermore, the permeable barrier layer is at least one layer of permeable geotextile, and the permeable barrier layer is attached to the back plate and the inner side of the four side plates of the model box.

[0013] Furthermore, the drainage pipeline includes multiple U-shaped drainage pipes, and multiple water inlets are provided on the pipe wall of the U-shaped drainage pipes, with the drainage outlets located at the ends of the U-shaped drainage pipes;

[0014] The U-shaped drain pipe includes a middle section and two parallel sections. The middle section of the U-shaped drain pipe is located inside the back panel of the model box, and the parallel sections of the U-shaped drain pipe are located inside the side panels of the model box.

[0015] Furthermore, the test soil sample includes a first clay layer, a second sand layer, a third clay layer, and a fourth sand layer, which are arranged sequentially from the back plate of the model box toward the sample loading port; the surface of the fourth sand layer is also covered with a surface geotextile and a saturated clay layer.

[0016] The technical solution of the method for preparing sand-clay interbedded soil of the present invention is as follows:

[0017] The preparation method using the above-mentioned apparatus for preparing interbedded sand and clay soil includes the following steps:

[0018] S1. Install drainage pipes and a water-permeable barrier layer inside the model box;

[0019] S2. For the clay used in the preparation of sand-clay interbedded soil, the relative density d of the clay particles is obtained based on the hydrostatic bottle method. s Based on the standard consolidation test, the dry density ρ of the clay required for the test was calculated. d ;

[0020] S3. For sand used in the preparation of sand-clay interbedded soil, obtain the minimum dry density ρ of the sand required for the test based on the funnel method or graduated cylinder method. dmin The maximum dry density ρ of the sand required for the experiment was obtained based on the vibration hammer method. dmax Based on the relative density of the sand required for the experiment, the dry density ρ of the sand was obtained. d ;

[0021] S4. Based on the required thickness of the first layer of clay for the experiment, calculate the required mass of the first layer of dry clay using the mass-density formula. Take a mass of M1 of dry clay and mix it thoroughly with sufficient water to prepare a uniform clay slurry.

[0022] S5. Start the drum centrifuge and spray the mud prepared in step S4 into the model box through the pipeline. The spraying process is carried out layer by layer from bottom to top. The centrifugal force of rotation is used to consolidate and load the test soil sample to simulate the in-situ stress level of the test soil sample.

[0023] S6. Based on the required thickness of the second layer of sand for the test, calculate the required mass of the second layer of dry sand using the mass-density formula. Take a mass of M2 of dry sand and mix it thoroughly with sufficient water to prepare a uniform sand slurry.

[0024] S7. Based on the required thickness of the third layer of clay for the experiment, calculate the required mass of the third layer of dry clay using the mass-density formula. Take a mass of M3 of dry clay and mix it thoroughly with sufficient water to prepare a uniform clay slurry.

[0025] S8. Restart the drum centrifuge and spray the sand slurry prepared in step S6 into the model box through the pipeline. The spraying process is carried out layer by layer from bottom to top. After the sand slurry is sprayed, spray the clay slurry prepared in step S7 onto the surface of the sand layer. The cohesion of the clay is used to enhance the self-support of the sand layer, and the centrifugal force of rotation is used to consolidate the test soil sample to simulate the in-situ stress level of the test soil sample.

[0026] S9. Based on the required thickness of the fourth layer of sand for the test, calculate the required mass of the fourth layer of dry sand using the mass-density formula. Take a mass of M4 of dry sand and mix it thoroughly with sufficient water to prepare a homogeneous sand slurry.

[0027] S10. Spray the prepared sand and soil slurry into the model box. After the sand slurry is sprayed, cover the surface of the sand layer with a layer of surface geotextile, and spray a layer of saturated clay on the surface of the surface geotextile. Use centrifugal force to consolidate the test soil sample to simulate the in-situ stress level of the test soil sample.

[0028] S11. Peel off the surface geotextile and saturated clay layer from step S10 to complete the preparation of sand-clay interbedded soil.

[0029] Furthermore, in step S2, based on the standard consolidation test, an e-log(p) curve is plotted with the void ratio e as the ordinate and the logarithm of the normal pressure p as the ordinate. The void ratio e is obtained from the curve based on the overburden stress p required for the test, and then the formula is used. Calculate the dry density of the clay required for the experiment, where ρ w This is the density of water.

[0030] Furthermore, in step S3, based on the required relative density D of the sand for the experiment... r According to the formula Calculate the dry density ρ of the sand. d .

[0031] Furthermore, in step S4, based on the cross-sectional area S of the sample loading port of the model box and the required thickness H1 of the first layer of clay for the test, the required volume V1 = SH1 of the first layer of clay for the test is calculated, and then calculated according to the formula M1 = ρ d V1 calculates the required mass M1 of dry clay.

[0032] Furthermore, in step S6, based on the cross-sectional area S of the sample loading port of the model box and the required thickness H2 of the second layer of sand for the test, the required volume V2 = SH2 of the second layer of sand for the test is calculated, and then calculated according to the formula M2 = ρ d V2 calculates the required mass of dry sand, M2.

[0033] Beneficial effects: The preparation device for this sand-clay interbedded soil employs a drum centrifuge, multiple model boxes, a permeable barrier layer, test soil samples, and drainage pipes. Multiple model boxes are circumferentially spaced inside the rotating drum of the drum centrifuge, with the sample loading port of each model box facing the center of the rotating drum. Before the test, the test soil sample is filled into the model box through the loading port. After the drum centrifuge is turned on, the rotating drum begins to rotate, generating centrifugal force radially outward. This centrifugal force can realistically simulate the in-situ stress level of the seabed soil layers, enabling the simultaneous and efficient preparation of multiple seabed geotechnical models.

[0034] Furthermore, a permeable barrier layer is placed inside the model box, and the test soil sample is filled inside the permeable barrier layer. The test soil sample includes at least two clay layers and a sand layer between the two clay layers. During centrifugation preparation, water in the test soil sample flows into the inlet through the permeable barrier layer and is discharged to the outside of the model box through the drainage pipe. Clay and sand particles are trapped inside the permeable barrier layer, effectively consolidating the clay and sand layers to form a sand-clay interlayer. In addition, the cohesion of the clay layer overcomes the problems of poor self-support and easy collapse of the sand layer during soil sample preparation, while ensuring the forming effect of the seabed geotechnical model and improving the accuracy of subsequent test results. Attached Figure Description

[0035] Figure 1 This is a three-dimensional schematic diagram of the apparatus for preparing sand-clay interbedded soil according to a specific embodiment of the present invention.

[0036] Figure 2 for Figure 1 A top view schematic diagram of the preparation device for medium sand and clay interbedded soil;

[0037] Figure 3 This is a three-dimensional schematic diagram of the model box in a specific embodiment of the preparation device for sand-clay interbedded soil of the present invention;

[0038] Figure 4 This is an exploded view of the model box in a specific embodiment of the preparation device for sand-clay interbedded soil of the present invention;

[0039] Figure 5 This is a cross-sectional schematic diagram of the preparation apparatus when the preparation method of sand-clay interbedded soil is completed in step S5 of a specific embodiment of the preparation apparatus of the present invention.

[0040] Figure 6 This is a cross-sectional view of the preparation apparatus when the preparation method of sand-clay interbedded soil is completed in step S8, according to a specific embodiment of the preparation apparatus of the present invention.

[0041] Figure 7 This is a cross-sectional view of the preparation apparatus when the preparation method of sand-clay interbedded soil is completed in step S10, as described in a specific embodiment of the preparation apparatus for sand-clay interbedded soil of the present invention.

[0042] Figure 8 This is a cross-sectional view of the preparation apparatus when step S11 of the sand-clay interbedded soil preparation method of the present invention is completed, in a specific embodiment of the preparation apparatus for sand-clay interbedded soil.

[0043] In the diagram: 1-rotating cylinder, 2-model box, 20-sample loading port, 3-permeable barrier layer, 4-test soil sample, 41-clay layer, 42-sand layer, 43-surface geotextile, 5-drainage pipe, 50-drainage outlet. Detailed Implementation

[0044] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0045] A specific embodiment 1 of the apparatus for preparing sand-clay interbedded soil of the present invention is as follows: Figures 1 to 8As shown, the preparation device for sand-clay interbedded soil includes a drum centrifuge and multiple model boxes 2. The drum centrifuge is equipped with a rotating cylinder 1, and multiple model boxes 2 are installed circumferentially at intervals inside the rotating cylinder 1. The model box 2 is also equipped with a permeable barrier layer 3, a test soil sample 4, and a drainage pipe 5. The model box 2 has a sample loading port 20 on the side facing the center of the rotating cylinder 1. The permeable barrier layer 3 is set inside the model box 2, and the test soil sample 4 is filled inside the permeable barrier layer 3.

[0046] The test soil sample 4 includes at least two clay layers 41 and a sand layer 42 between the two clay layers 41. The layers of the at least two clay layers 41 and the sand layer 42 are all arranged perpendicular to the radial direction of the rotating cylinder 1. The drainage pipe 5 is arranged between the model box 2 and the permeable barrier layer 3. The drainage pipe 5 has an inlet and an outlet 50. The inlet of the drainage pipe 5 is located inside the model box 2, and the outlet 50 of the drainage pipe 5 extends to the outside of the sample loading port 20.

[0047] The preparation device for this sand-clay interbedded soil adopts a design consisting of a drum centrifuge, multiple model boxes 2, a permeable barrier layer 3, test soil samples 4, and drainage pipes 5. The multiple model boxes 2 are circumferentially spaced inside the rotating drum 1 of the drum centrifuge, with the sample loading port 20 of each model box 2 facing the center of the rotating drum 1. Before the test, the test soil sample 4 is filled into the model box 2 through the sample loading port 20. After the drum centrifuge is turned on, the rotating drum 1 begins to rotate, generating centrifugal force radially outward along the rotating drum 1. This centrifugal force can realistically simulate the in-situ stress level of the seabed soil layers, enabling the simultaneous and efficient preparation of multiple seabed geotechnical models.

[0048] Furthermore, a permeable barrier layer 3 is located inside the model box 2, and the test soil sample 4 is filled inside the permeable barrier layer 3. The test soil sample 4 includes at least two clay layers 41 and a sand layer 42 between the two clay layers 41. During the centrifugation preparation process, the water in the test soil sample 4 flows into the inlet through the permeable barrier layer 3 and is discharged to the outside of the model box 2 through the drainage pipe 5 and the drainage outlet 50. The clay particles and sand particles are blocked inside the permeable barrier layer 3, so that the clay layer 41 and the sand layer 42 are effectively consolidated to form a sand-clay interlayer. In addition, the cohesion of the clay layer 41 overcomes the problem of poor self-support of the sand layer 42 and easy collapse during soil sample preparation, while ensuring the forming effect of the seabed strata geotechnical model and improving the accuracy of subsequent test results.

[0049] In this embodiment, the model box 2 is rectangular in shape and includes a back plate and four side plates fixedly connected to the back plate. The back plate of the model box 2 is attached to the wall of the rotating cylinder 1. That is, the model box 2 is an open-top rectangular box. Under the action of centrifugal force, the test soil sample 4 is stacked layer by layer on the back plate of the model box 2. The side plates in the four directions can prevent the mud-like test soil sample 4 from overflowing outward.

[0050] As a further preferred embodiment, the permeable barrier layer 3 is at least one layer of permeable geotextile, which is attached to the back plate and the inner sides of the four side plates of the model box 2. The permeable pore size of the permeable barrier layer 3 is larger than that of the clay and sand particles, which prevents clay and sand particles from being lost from the inside of the model box 2 during the preparation process, thus ensuring the molding effect of the prepared sand-clay interlayer geotechnical model.

[0051] Specifically, the drainage pipe 5 includes multiple U-shaped drainage pipes, and multiple water inlets are opened on the pipe wall of the U-shaped drainage pipes. The drainage outlet 50 is located at the end of the U-shaped drainage pipe. The U-shaped drainage pipe includes a middle section and two parallel sections. The middle section of the U-shaped drainage pipe is located inside the back plate of the model box 2, and the parallel sections of the U-shaped drainage pipe are located inside the side plate of the model box 2.

[0052] In addition, the test soil sample 4 includes a first clay layer, a second sand layer, a third clay layer, and a fourth sand layer, which are arranged sequentially from the back plate of the model box 2 towards the sample loading port 20. The surface of the fourth sand layer is also covered with a surface geotextile 43 and a saturated clay layer 41. The surface geotextile 43 and the saturated clay layer 41 stabilize the fourth sand layer, preventing it from collapsing and ensuring that the test soil sample 4 can be consolidated using centrifugal force.

[0053] The preparation method using the above-mentioned apparatus for preparing interbedded sand and clay soil includes the following steps:

[0054] S1. Install drainage pipes 5 and water-permeable barrier layer 3 inside the model box 2;

[0055] S2. For the clay used in the preparation of sand-clay interbedded soil, the relative density d of the clay particles is obtained based on the hydrostatic bottle method. s Based on the standard consolidation test, the dry density ρ of the clay required for the test was calculated. d In step S2, based on the standard consolidation test, an e-log(p) curve is plotted with the void ratio e as the ordinate and the logarithm of the normal pressure p as the ordinate. The void ratio e is obtained from the curve based on the overburden stress p required for the test, and the formula is used to calculate the void ratio e. Calculate the dry density of the clay required for the experiment, where ρ w This is the density of water.

[0056] S3. For sand used in the preparation of sand-clay interbedded soil, obtain the minimum dry density ρ of the sand required for the test based on the funnel method or graduated cylinder method. dmin The maximum dry density ρ of the sand required for the experiment was obtained based on the vibration hammer method. dmax Based on the relative density of the sand required for the experiment, the dry density ρ of the sand was obtained. d In step S3, based on the required relative density D of the sand for the experiment... r According to the formula Calculate the dry density ρ of the sand. d .

[0057] S4. Based on the required thickness of the first layer of clay for the experiment, calculate the required mass of the first layer of dry clay using the mass-density formula. Take a mass of M1 of dry clay and mix it thoroughly with sufficient water to prepare a homogeneous clay slurry. In step S4, based on the cross-sectional area S of the sample loading port of the model box and the required thickness H1 of the first layer of clay for the experiment, calculate the required volume V1 = SH1 of the first layer of clay for the experiment. According to the formula M1 = ρ d V1 calculates the required mass M1 of dry clay.

[0058] S5. Start the drum centrifuge and spray the clay slurry prepared in step S4 into the model box through the pipeline. The spraying process should proceed from bottom to top, layer by layer. Figure 5 As shown, centrifugal force is used to consolidate the test soil sample to simulate the in-situ stress level of the test soil sample.

[0059] S6. Based on the required thickness of the second layer of sand for the experiment, calculate the required mass of the second layer of dry sand using the mass-density formula. Take a mass of M2 of dry sand and mix it thoroughly with sufficient water to prepare a homogeneous sand slurry. In step S6, based on the cross-sectional area S of the sample loading port of the model box and the required thickness H2 of the second layer of sand for the experiment, calculate the required volume V2 = SH2 of the second layer of sand for the experiment. Then, use the formula M2 = ρ d V2 calculates the required mass of dry sand, M2.

[0060] S7. Based on the required thickness of the third layer of clay for the experiment, calculate the required mass of the third layer of dry clay using the mass-density formula. Referring to the calculation method of the mass M1 of the dry clay in step S4, obtain the mass M3 of the third layer of dry clay. Take the dry clay with a mass of M3 and mix it thoroughly with sufficient water to prepare a uniform clay slurry.

[0061] S8. Restart the drum centrifuge and spray the sand slurry prepared in step S6 into the model box through the pipeline, spraying layer by layer from bottom to top; after the sand slurry is sprayed, spray the clay slurry prepared in step S7 onto the surface of the sand layer, such as... Figure 6As shown, the cohesion of clay is used to enhance the self-support of the sand layer, and centrifugal force is used to consolidate the test soil sample to simulate the in-situ stress level of the test soil sample.

[0062] S9. Based on the required thickness of the fourth layer of sand for the experiment, and using the mass-density formula, refer to the calculation method of the mass M1 of the dry clay in step S4 to obtain the mass M4 of the fourth layer of dry sand. Take the dry sand with a mass of M4 and mix it thoroughly with sufficient water to prepare a homogeneous sand slurry.

[0063] S10. Spray the prepared sand slurry into the model box. After the slurry spraying is complete, cover the surface of the sand layer with a layer of geotextile, and then spray a layer of saturated clay onto the surface of the geotextile. Figure 7 As shown, centrifugal force was used to consolidate the soil sample 4 to simulate the in-situ stress level of the soil sample 4.

[0064] S11. Stripping the surface geotextile and saturated clay layer from step S10, such as Figure 8 As shown, after stripping the surface geotextile and saturated clay layer, the seabed geotechnical model consisting of the first clay layer, the second sand layer, the third clay layer and the fourth sand layer is retained to complete the preparation of the sand-clay interlayer soil.

[0065] The specific embodiments of the method for preparing sand-clay interbedded soil of the present invention are the same as the specific embodiments of the method for preparing sand-clay interbedded soil using the preparation apparatus of the present invention, and will not be repeated here.

[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an apparatus for preparing interbedded sand and clay soil, characterized in that, The preparation device for the sand-clay interbedded soil includes a drum centrifuge and multiple model boxes. The drum centrifuge is equipped with a rotating cylinder, and the multiple model boxes are circumferentially spaced inside the rotating cylinder. The model box is also equipped with a permeable barrier layer, a test soil sample and a drainage pipe. The model box has a sample loading port on the side facing the center of the rotating cylinder. The permeable barrier layer is set inside the model box, and the test soil sample is filled inside the permeable barrier layer. The test soil sample includes at least two clay layers and a sand layer between the two clay layers, and the layers of the at least two clay layers and the sand layer are arranged perpendicular to the radial direction of the rotating cylinder; The drainage pipe is disposed between the model box and the water-permeable barrier layer. The drainage pipe has an inlet and an outlet. The inlet of the drainage pipe is located inside the model box, and the outlet of the drainage pipe extends to the outside of the sample loading port. The model box is rectangular in shape and includes a back plate and four side plates fixedly connected to the back plate. The back plate of the model box is attached to the wall of the rotating cylinder. The permeable barrier layer is at least one layer of permeable geotextile, and the permeable barrier layer is attached to the back plate and the inner side of the four side plates of the model box. The drainage pipeline includes multiple U-shaped drainage pipes, and multiple water inlets are provided on the pipe walls of the U-shaped drainage pipes. The drainage outlets are located at the ends of the U-shaped drainage pipes. The U-shaped drain pipe includes a middle section and two parallel sections. The middle section of the U-shaped drain pipe is located inside the back panel of the model box, and the parallel sections of the U-shaped drain pipe are located inside the side panels of the model box. The preparation method includes the following steps: S1. Install drainage pipes and a water-permeable barrier layer inside the model box; S2. For the clay used in the preparation of sand-clay interbedded soil, the relative density of clay particles is obtained based on the hydrostatic bottle method. Based on the standard consolidation test, the dry density of the clay required for the test was calculated. ; S3. For sand used in the preparation of sand-clay interbedded soil, obtain the minimum dry density of the sand required for the test based on the funnel method or graduated cylinder method. The maximum dry density of the sand required for the experiment was obtained based on the vibration hammer method. Based on the required relative density of the sand for the experiment, the dry density of the sand was determined. ; S4. Based on the required thickness of the first clay layer for the experiment, calculate the required mass of the first dry clay layer using the mass-density formula, and take the mass as... The dry clay is thoroughly mixed with sufficient water to prepare a uniform clay slurry. S5. Start the drum centrifuge and spray the mud prepared in step S4 into the model box through the pipeline. The spraying process is carried out layer by layer from bottom to top. The centrifugal force of rotation is used to consolidate and load the test soil sample to simulate the in-situ stress level of the test soil sample. S6. Based on the required thickness of the second layer of sand for the experiment, calculate the required mass of the second layer of dry sand using the mass-density formula, and take the mass as... The dry sand is thoroughly mixed with sufficient water to prepare a uniform sand slurry; S7. Based on the required thickness of the third clay layer for the experiment, calculate the required mass of the third dry clay layer using the mass-density formula, and take the mass as... The dry clay is thoroughly mixed with sufficient water to prepare a uniform clay slurry. S8. Restart the drum centrifuge and spray the sand slurry prepared in step S6 into the model box through the pipeline. The spraying process is carried out layer by layer from bottom to top. After the sand slurry is sprayed, spray the clay slurry prepared in step S7 onto the surface of the sand layer. The cohesion of the clay is used to enhance the self-support of the sand layer, and the centrifugal force of rotation is used to consolidate the test soil sample to simulate the in-situ stress level of the test soil sample. S9. Based on the required thickness of the fourth sand layer for the experiment, calculate the required mass of the fourth dry sand layer using the mass-density formula, and take the mass as... The dry sand is thoroughly mixed with sufficient water to form a homogeneous sand slurry. S10. Spray the prepared sand and soil slurry into the model box. After the sand and soil slurry is sprayed, cover the surface of the sand layer with a layer of surface geotextile, and spray a layer of saturated clay on the surface of the surface geotextile. Use centrifugal force to consolidate the test soil sample to simulate the in-situ stress level of the test soil sample. S11. Peel off the surface geotextile and saturated clay layer from step S10 to complete the preparation of sand-clay interbedded soil.

2. The preparation method of the apparatus for preparing sand-clay interbedded soil according to claim 1, characterized in that, The test soil sample includes a first clay layer, a second sand layer, a third clay layer, and a fourth sand layer, which are arranged sequentially from the back plate of the model box toward the sample loading port; the surface of the fourth sand layer is also covered with a surface geotextile and a saturated clay layer.

3. The preparation method of the apparatus for preparing sand-clay interbedded soil according to claim 2, characterized in that, In step S2, based on the standard consolidation test, the porosity is... The vertical axis represents the normal pressure. Using the logarithm of the x-axis, plot the graph. The curve is used to obtain the corresponding porosity from the overlying stress required for the experiment. Using the formula Calculate the dry density of the clay required for the experiment, where This is the density of water.

4. The preparation method of the apparatus for preparing sand-clay interbedded soil according to claim 2, characterized in that, in In step S3, based on the relative density of the sand required for the experiment... According to the formula Calculate the dry density of the sand. .

5. The preparation method of the apparatus for preparing sand-clay interbedded soil according to claim 2, characterized in that, In step S4, the cross-sectional area of ​​the sample loading port corresponding to the model box is determined. and the required thickness of the first layer of clay for the experiment Calculate the volume of the first layer of clay required for the experiment. According to the formula Calculate the required mass of dry clay. .

6. The preparation method of the apparatus for preparing sand-clay interbedded soil according to claim 2, characterized in that, in In step S6, the cross-sectional area of ​​the sample loading port corresponding to the model box is determined. and the required thickness of the second layer of sand for the experiment Calculate the volume of the second layer of sand required for the experiment. According to the formula Calculate the required mass of dry sand. .

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