A preparation method of a centrifuge shaking table test heterogeneous model

Abstract

The application discloses a preparation method of a heterogeneous model for centrifuge shaking table test. The method comprises the following steps: measuring the depth of a prototype site, the thicknesses of liquefiable soil layers and overburden layers in the prototype site, determining the centrifugal acceleration of the test and calculating the thickness of a model liquefiable soil layer, determining the thicknesses of heterogeneous material layers and the thickness and process of an artificial interface functional layer in the model according to the material specific weight, preparing the model layer by layer according to the thickness of the model liquefiable soil layer and the heterogeneous material layers in the model, and performing simulation test on the actual site by using the prepared model to obtain the physical properties such as the acceleration, pore water pressure and shear wave velocity of the soil layers in the actual site. The application breaks through the bottleneck of the simulation capacity of the existing centrifuge shaking table and improves the simulation scale of the centrifuge shaking table in the depth direction without changing the hardware facilities of the centrifuge shaking table based on the stress equivalence idea.

Description

Technical Field

[0001] This invention belongs to the field of physical model test theory technology, and specifically relates to a method for preparing a heterogeneous model for a centrifuge shaking table test. Background Technology

[0002] In my country's engineering construction, there are some sites with deep foundations. When constructing high dams, high embankments, or tall superstructures on these sites, the underlying foundation soil is under high overburden stress, posing a risk of liquefaction. However, my country's seismic design code only provides empirical liquefaction assessment for soil layers up to 20m below the surface. The US NCEER code recommends liquefaction assessment for soil layers up to 23m below the surface, while the recommended depths in Japanese and New Zealand codes do not exceed 20m. Given the limited ability of existing codes to assess liquefaction, conducting physical model tests to study conditions with deep overburden layers and high overburden stress has become a new approach. Centrifuge shaking table physical simulation tests, with their ability to reproduce the original stress field, are increasingly being used.

[0003] The principle of the centrifuge model experiment is that the centrifuge arm rotates the model box with an angular velocity ω, applying a hypergravity field with an acceleration N times that of gravity to the model box, where N = ω. 2 With a stress ratio of r / g, if the same material as the prototype is used, the geometric dimensions of the prototype site can be reduced by a factor of N to achieve a stress field consistent with the prototype. Therefore, centrifuge testing is also called isostatic testing, primarily overcoming a series of problems caused by unequal stress in constant gravity testing. However, centrifuge testing has insufficient simulation capabilities when simulating conditions such as deep overburden layers. In some parts of western my country, deep overburden layers can reach hundreds of meters, while the world's most advanced centrifuge shaking table at UC Davis has a simulation capability of only 52.5 meters. Therefore, improving the simulation capability of centrifuges is an urgent technical problem to be solved. Summary of the Invention

[0004] To address the problems in the background technology and improve the simulation scale of centrifuge shaking tables along the depth direction, the present invention aims to provide a method for preparing a heterogeneous model for centrifuge shaking table tests. The basic idea of ​​the present invention is to use heterogeneous materials several times larger than the in-situ soil to increase part of the self-weight stress of the model, ensure that the overburden stress of the soil layer under study is equivalent, and thus realize the study of the dynamic response of the model under constant stress test conditions.

[0005] The technical solution adopted in this invention is as follows, including the following steps:

[0006] Step S1: First, obtain the depth H of the test prototype site. p And the thickness h of the liquefiable soil layer in the prototype site s pThe thickness h of the overburden layer in the prototype site is obtained by processing it according to the following formula. t p :

[0007] h t p =H p -h s p

[0008] Among them, H p h represents the total depth of the prototype site to be tested. s p The thickness of the liquefiable soil layer in the prototype site.

[0009] Step S2: Next, determine the centrifugal acceleration 'a' for the centrifuge shaking table test to be carried out, a = N * g, where N represents the preset scaling ratio during the centrifuge shaking table test, and g represents the gravitational acceleration, taken as g = 9.80 m / s². 2 And obtain the thickness h of the liquefiable soil layer unit of the experimental model. k m ;

[0010] Step S3: Next, based on the thickness h of the overburden layer in the prototype site... t p Obtain the stress σ of the overburden layer in the prototype site. v The specific weight γ of the pre-selected heterogeneous material is determined, and the thickness h of the overlying heterogeneous material layer of the experimental model is obtained based on the specific weight γ. t m ;

[0011] Step S4: Based on the above steps, the thickness h of the liquefiable soil layer element in the model is determined. k m and the thickness h of the overlying heterogeneous material layer t m The target experimental model is prepared layer by layer, and then the prepared target experimental model is used to conduct simulation tests on the prototype site to obtain the acceleration, pore water pressure and shear wave velocity of the soil layer in the prototype site.

[0012] The prototype site includes natural overburden, foundation pit, dam, etc.

[0013] In step S2, the thickness h of the liquefiable soil layer unit in the experimental model k m The specific steps to obtain it are as follows:

[0014] First, the liquefiable soil layer in the prototype site is divided into n prototype liquefiable soil layer units. Then, the thickness of each prototype liquefiable soil layer unit is measured. Next, the thickness h of the k-th liquefiable soil layer unit in the experimental model is obtained according to the following formula.k m :

[0015] h k m =h k p / N

[0016] Where k represents the ordinal number of the prototype liquefiable soil layer unit, the liquefiable soil layer in the prototype site is layered from top to bottom, k = 1, 2 ... n, n represents the total number of prototype liquefiable soil layer units, h k p This represents the thickness of the k-th prototype liquefiable soil layer unit.

[0017] In step S3, the material density γ and the thickness h of the overlying heterogeneous material layer are obtained. t m The specific steps are as follows:

[0018] Step S31: First, perform a density calibration test on the pre-prepared heterogeneous material to obtain the material density ρ of the heterogeneous material. Then, use the following formula to obtain the material specific weight γ of the heterogeneous material:

[0019] γ = ρ * g;

[0020] Step S32: Obtain the thickness h of the overlying heterogeneous material layer of the experimental model using the following formula. t m :

[0021] h t m =σ v / (N*γ).

[0022] The specific steps of S4 are as follows:

[0023] Step S41: First, take the soil of the liquefiable soil layer in the prototype site as the calibration soil. In the indoor laboratory, use the calibration soil as raw material to pour the liquefiable soil layer in layers to form the experimental model.

[0024] Step S42: Pour an artificial interface functional layer onto the upper surface of the liquefiable soil layer of the experimental model to form the initial model;

[0025] Step S43: Place the initial model inside a vacuum chamber, and then continuously inject a viscous liquid with a viscosity N times that of water into the initial model, while simultaneously saturating the initial model with soil.

[0026] If the liquid surface formed after the viscous liquid is injected is flush with the upper surface of the artificial interface functional layer, it indicates that the soil saturation is complete. Stop injecting the viscous liquid and then remove the initial model from the vacuum box.

[0027] If the liquid level formed after the injection of viscous liquid is lower than the upper surface of the artificial interface functional layer, it indicates that the soil saturation is not complete, and the injection of viscous liquid should continue.

[0028] Step S44: After the initial model is saturated, heterogeneous material is continuously poured onto the upper surface of the initial model, forming a heterogeneous material layer on the upper surface of the initial model. Simultaneously, sensors are embedded within the heterogeneous material layer. When the thickness of the heterogeneous material layer reaches the thickness h of the overlying heterogeneous material layer... t m The casting of heterogeneous materials was stopped at a certain time, and the initial model with the heterogeneous material layer cast at this time was used as the target experimental model. Finally, the prepared target experimental model was used to simulate the prototype site to be tested in order to obtain the acceleration, pore water pressure and shear wave velocity of the prototype site.

[0029] In step S41, the specific steps for casting the liquefiable soil layer of the experimental model are as follows: according to the thickness of the liquefiable soil layer unit of the n experimental models, n layers of liquefiable soil layer units of the experimental models are cast respectively, and sensors are buried between adjacent liquefiable soil layer units of the experimental models. The liquefiable soil layer of the experimental model is mainly formed by stacking n layers of liquefiable soil layer units of the experimental models from top to bottom.

[0030] In step S42, the thickness h of the artificial interface functional layer is obtained according to the following formula:

[0031]

[0032] Where, ρ 异 ρ' is the density of the heterogeneous material layer overlying the experimental model, ρ′ is the effective density of the liquefiable soil layer of the experimental model, and k is the density of the heterogeneous material layer overlying the experimental model. m k is the permeability coefficient of the artificial interface functional layer. p denoted as the permeability coefficient of the heterogeneous material layer covering the experimental model.

[0033] The artificial interface functional layer is designed with a serrated shape, which allows the liquefiable soil layer and the heterogeneous material layer of the experimental model to be tightly bonded together through the serrated artificial interface functional layer.

[0034] In step S44, the acceleration, pore water pressure, and shear wave velocity of the prototype site are obtained in the following ways:

[0035] First, a basic soil experiment is conducted on the target experimental model to obtain the acceleration, pore water pressure, and shear wave velocity of the target experimental model. The acceleration of the prototype site is the acceleration of the target experimental model / N, the pore water pressure of the prototype site is the same as that of the target experimental model, and the shear wave velocity of the prototype site is the same as that of the target experimental model.

[0036] The sensor in step S4 is an acceleration sensor, a pressure sensor, or a portable bending element sensor.

[0037] To enhance the maximum simulation scale of current centrifuge shaking tables, this invention proposes a method for preparing a heterogeneous model without modifying existing hardware. Based on the concept of stress equivalence, it employs high-density heterogeneous materials to increase part of the model's self-weight stress, ensuring that the overlying stress of the soil layer under study is equivalent to that in situ, thus restoring the true stress field. Ultimately, this achieves the goal of reflecting the in-situ response in the centrifuge shaking table test results. This invention overcomes the limitations of existing centrifuge shaking table simulation capabilities without altering the centrifuge shaking table hardware, thereby improving the simulation scale along the depth direction.

[0038] This invention is applicable to centrifuge shaking table tests simulating deep overburden layers and high-fill overlying structures. Based on the concept of stress equivalence, it uses high-density heterogeneous materials to increase part of the model's self-weight stress, ensuring that the stress of the soil layer under study and the model's permeability coefficient are consistent with the prototype, thus restoring the real stress field and permeability boundary. Ultimately, it achieves the goal of reflecting the in-situ response in the centrifuge shaking table test results. It is simple to operate, low-carbon, and environmentally friendly.

[0039] Beneficial results of the present invention:

[0040] 1. No modifications were made to the centrifuge vibration table hardware. A relatively simple model preparation process was used, which reduced the difficulty of operation and simplified the test process to the greatest extent. Furthermore, the heterogeneous material does not come into contact with the oil, making it reusable, clean, hygienic, energy-saving, emission-reducing, low-carbon, and environmentally friendly.

[0041] 2. Based on the principle of stress equivalence, a heterogeneous material layer was poured on top of the soil layer of interest, ensuring the mechanical equivalence of the overlying stress and the authenticity of the centrifuge shaking table test results.

[0042] 3. Based on the principle of permeability equivalence, an artificial interface functional layer is added above the soil layer of interest and between the heterogeneous material layer to ensure that the pore water dissipation time of the model is consistent with that of the prototype.

[0043] 4. Based on the principle of dynamic similarity, ensure that the dynamic shear stress transmitted at the boundary of the heterogeneous model is not distorted.

[0044] 5. It avoids stress reflection, minimizing the refraction and reflection of seismic waves at material interfaces.

[0045] 6. This method can be applied to the centrifuge acceleration value Ng and the thickness h1 of the soil layer of interest model. m Changes alter the thickness h2 of the material layer in the heterogeneous model m Flexible and adaptable. Attached Figure Description

[0046] Figure 1 A schematic diagram illustrating the basic principles of similar design;

[0047] Figure 2 This is a schematic cross-sectional view of the centrifuged heterogeneous model in the embodiment. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0049] In a specific embodiment, the prototype site to be tested is simplified to a total overburden layer with a depth of 70m. The soil within 8-10m above the bottom of the total overburden layer is taken as the research object. The soil type of the total overburden layer is mainly saturated sandy soil, and the soil density is taken as 2g / cm³. 3 The permeability coefficient is taken as 6*10 -2 cm / s, the permeability coefficient of the geotextile is taken as 1*10 cm / s. -6 cm / s. The present invention prepares a target soil layer model equivalent to the overlying stress of the prototype site in a centrifuge shaking table test. The specific steps of the present invention are as follows:

[0050] Step S1: First, obtain the depth H of the test prototype site. p And the thickness h of the liquefiable soil layer in the prototype site s p The thickness h of the overburden layer in the prototype site is obtained by processing it according to the following formula. t p :

[0051] h t p =H p -h s p

[0052] Among them, H p h represents the total depth of the prototype site to be tested. s p The thickness of the liquefiable soil layer in the prototype site is given by the superscript p, which indicates the prototype site; in actual implementation, the depth H of the prototype site is... p =70m, the thickness h of the liquefiable soil layer in the prototype site s p Take 9m as an example, and the thickness of the soil cover layer h at the prototype site. t p =H p -h s p=61m.

[0053] Step S2: Next, determine the centrifugal acceleration 'a' for the centrifuge shaking table test to be carried out, a = N * g, where N represents the preset scaling ratio during the centrifuge shaking table test, and g represents the gravitational acceleration, taken as g = 9.80 m / s². 2 And obtain the thickness h of the liquefiable soil layer unit of the experimental model. k m ;

[0054] The model to be prepared is placed in an external model box.

[0055] In practice, based on the performance of the external centrifuge and the size of the model box, a centrifugal acceleration of 60g was selected, and the scaling ratio N = 60, i.e., prototype size / experimental model size = 60, and the thickness h of the liquefiable soil layer of the experimental model was calculated. s m =h s p / N=15cm;

[0056] In step S2, the thickness h of the liquefiable soil layer unit in the experimental model is... k m The specific steps to obtain it are as follows:

[0057] First, the liquefiable soil layer in the prototype site is divided into n prototype liquefiable soil layer units. Then, the thickness of each prototype liquefiable soil layer unit is measured. Next, the thickness h of the k-th liquefiable soil layer unit in the experimental model is obtained according to the following formula. k m :

[0058] h k m =h k p / N

[0059] Where k represents the ordinal number of the prototype liquefiable soil layer unit, the liquefiable soil layer in the prototype site is layered from top to bottom, k = 1, 2 ... n, n represents the total number of prototype liquefiable soil layer units, h k p This represents the thickness of the k-th prototype liquefiable soil layer unit.

[0060] Step S3: Next, based on the thickness h of the overburden layer in the prototype site... t p Obtain the stress σ of the overburden layer in the prototype site. v The specific weight γ of the pre-selected heterogeneous material is determined, and the thickness h of the overlying heterogeneous material layer of the experimental model is obtained based on the specific weight γ. t m ;

[0061] In step S3, the material density γ and the thickness h of the overlying heterogeneous material layer are obtained. t m The specific steps are as follows:

[0062] Step S31: First, conduct a density calibration test on the pre-prepared heterogeneous material to obtain the material density ρ when the heterogeneous material falls freely at a preset collapse height H. Then, use the following formula to obtain the material specific weight γ of the heterogeneous material:

[0063] γ = ρ * g;

[0064] The specific procedure for the density calibration test is as follows: at a preset collapse height H, the heterogeneous material is allowed to fall freely into a cubic container with a volume of V. After the cubic container is filled with heterogeneous material, the total weight of the heterogeneous material in the cubic container is weighed as M. The material density is obtained by the formula ρ=M / V.

[0065] In this embodiment, a density calibration test was conducted on heterogeneous materials. Lead sand was used as the heterogeneous material. During the test, the lead sand was dropped freely from a height of 50cm from the experimental table into a metal container with sides of 10cm. After the container was full, the surface was smoothed to remove excess lead sand, and the tare mass was measured to be 6577.2g. The density ρ can then be calculated using the definition of density. 铅 =M / L 3 =6577.2g / 1000cm 3 =6.577g / cm 3 ;

[0066] Step S32: Obtain the thickness h of the overlying heterogeneous material layer of the experimental model using the following formula. t m :

[0067] h t m =σ v / (N*γ).

[0068] In practical implementation, the stress σ of the overburden layer in the prototype site v =ρ 土 gh t p =2 * 9.8 * 61 = 1195.6 kPa. h is calculated based on the density of lead sand and the centrifugal acceleration value of the centrifuge. t m =σ v / (N*γ)=30.9cm; After the above calculations are completed, the model preparation will begin;

[0069] Step S4: Based on the above steps, the thickness h of the liquefiable soil layer element in the model is determined. k mand the thickness h of the overlying heterogeneous material layer t m The target experimental model is prepared layer by layer, and then the prepared target experimental model is used to conduct simulation tests on the prototype site to obtain the physical properties of the soil layer in the prototype site, such as acceleration, pore water pressure and shear wave velocity.

[0070] Prototype sites for implementation include natural overburden, foundation pits, dams, etc.

[0071] Step S4 is as follows:

[0072] Step S41: First, take the soil of the liquefiable soil layer in the prototype site as the calibration soil. In the indoor laboratory, use the calibration soil as raw material to pour the liquefiable soil layer in layers to form the experimental model.

[0073] The specific steps for casting the liquefiable soil layer of the experimental model are as follows: according to the thickness of the liquefiable soil layer unit of the n experimental models, the n layers of liquefiable soil layer units of the experimental models are cast respectively, and sensors are buried between adjacent liquefiable soil layer units of the experimental models. The liquefiable soil layer of the experimental model is mainly formed by the n layers of liquefiable soil layer units of the experimental models stacked from top to bottom.

[0074] During the pouring process, the thickness of the k-th liquefiable soil layer unit in the experimental model is h. k m k = 1, 2, ..., n, where n represents the total number of liquefiable soil layers in the experimental model.

[0075] In practice, acceleration sensors and bore pressure sensors are installed at distances of 4cm, 8cm, and 12cm from the bottom of the model box, and bending element sensors are installed at distance of 8cm from the bottom of the model box.

[0076] Step S42: Pour an artificial interface functional layer on the upper surface of the liquefiable soil layer of the experimental model to form an initial model. The initial model is mainly composed of the model liquefiable soil layer and the artificial interface functional layer stacked together.

[0077] Step S43: Place the initial model inside a vacuum chamber, and then continuously inject a viscous liquid with a viscosity N times that of water into the initial model, while simultaneously saturating the initial model with soil.

[0078] If the liquid surface formed after the viscous liquid is injected is flush with the upper surface of the artificial interface functional layer, it indicates that the soil saturation is complete. Stop injecting the viscous liquid and then remove the initial model from the vacuum box.

[0079] If the liquid level formed after the injection of viscous liquid is lower than the upper surface of the artificial interface functional layer, it indicates that the soil saturation is not complete, and the injection of viscous liquid should continue.

[0080] If the liquid level formed after the injection of viscous liquid is higher than the upper surface of the artificial interface functional layer, it indicates that the soil is saturated and there is excess viscous liquid. Stop injecting viscous liquid and use a syringe to extract the excess viscous liquid so that the viscous liquid does not overflow the top surface of the artificial interface functional layer. Then take the initial model out of the vacuum box.

[0081] In practice, the artificial interface functional layer uses geotextile material. A coarse sand layer is uniformly poured on top of the liquefiable soil layer of the experimental model, and a geotextile layer is laid on top of the coarse sand layer. The thickness of the geotextile is determined to be 0.6 cm according to the formula to ensure that the pore water at the bottom of the model dissipates in the same time as the prototype and to transfer the dynamic shear stress. A methyl silicone oil solution with a viscosity of 60 times that of water is used as a saturated solution (viscous liquid). The model is saturated and vacuumed. After the model is saturated, it is taken out and the excess oil is extracted with a syringe to prevent the oil from overflowing the top surface of the artificial interface functional layer.

[0082] Step S44: After the initial model is saturated, heterogeneous material is continuously poured onto the upper surface of the initial model, forming a heterogeneous material layer on the upper surface of the initial model. Simultaneously, sensors are embedded within the heterogeneous material layer. When the thickness of the heterogeneous material layer reaches the thickness h of the overlying heterogeneous material layer... t m The casting of heterogeneous materials is stopped at a certain time, and the initial model with the heterogeneous material layer cast at this time is used as the target experimental model. The target experimental model is mainly formed by layering the heterogeneous material layer, the artificial interface functional layer and the liquefiable soil layer of the experimental model from top to bottom. Finally, the prepared target experimental model is used to simulate the prototype site to be tested in order to obtain the physical properties of the prototype site such as acceleration, pore water pressure and shear wave velocity.

[0083] In step S44, the acceleration, pore water pressure, and shear wave velocity of the prototype site are obtained as follows: First, a foundation soil test is conducted on the target experimental model to obtain the acceleration, pore water pressure, and shear wave velocity of the target experimental model. The acceleration of the prototype site is the acceleration of the target experimental model divided by N. The pore water pressure of the prototype site is the same as that of the target experimental model. The shear wave velocity of the prototype site is the same as that of the target experimental model. The conversion relationship between the physical properties of the target experimental model and the prototype site is shown in Table 1.

[0084] Table 1. Criteria for Converting Experimental Results of Foundation Soil

[0085]

[0086] In practice, lead sand is poured starting 50cm from the top surface of the artificial interface functional layer, maintaining this spacing throughout the pouring process. Accelerometers are placed at distances of 4cm, 15cm, and 26cm from the top surface of the artificial interface functional layer. The model is complete when the heterogeneous material layer reaches the designated height (48cm from the bottom of the model box). Figure 2 As shown.

[0087] In step S42, the artificial interface functional layer uses materials such as geotextiles that have the ability to dissipate energy and reduce stress reflection.

[0088] The sensor in step S4 is an acceleration sensor, a pressure sensor, or a portable bending element sensor, etc.

[0089] The method of this invention incorporates three similarity design principles: stress similarity, permeability similarity, and dynamic similarity;

[0090] Similar design principle SL1: After the centrifuge is switched to Ng, Figure 1 The self-weight stress at the bottom of the overlying heterogeneous material layer in the left-middle model (Model A) and Figure 1 The self-weight stress at the bottom of the overlying sand layer is the same in the equivalent model on the right (Model B);

[0091] Similarity Design Principle SL2: When the shaking table vibrates, the dynamic shear stress time history transmitted upward by the artificial interface functional layer in Model A is the same as the dynamic shear stress time history transmitted upward by the virtual layered interface in Model B.

[0092] Similar design principle SL3: After vibration causes excess pore pressure in the liquefiable soil layer, the saturated fluid infiltration time of the liquefiable layer in Model A into the overburden is the same as the fluid infiltration time of the liquefiable layer into the overburden in Model B.

[0093] In step S42, the thickness h of the artificial interface functional layer is obtained according to the following formula:

[0094]

[0095] Where, ρ 异 ρ' is the density of the heterogeneous material layer overlying the experimental model, ρ′ is the effective density of the liquefiable soil layer of the experimental model, and k is the density of the heterogeneous material layer overlying the experimental model. m k is the permeability coefficient of the artificial interface functional layer. p denoted as the permeability coefficient of the heterogeneous material layer covering the experimental model.

[0096] In step S42, the selection of materials and the fabrication process of the artificial interface functional layer should ensure that the dynamic shear stress time history transmitted by the artificial interface of the experimental model (i.e., model A) is consistent with the dynamic shear stress time history transmitted by the virtual layered interface of model B. The model fabrication process includes, but is not limited to, the following: Figure 1The serrated interlocking design described herein can fit tightly with the overlying heterogeneous material layer to transfer dynamic shear stress propagating upwards from the lower layer.

[0097] The artificial interface functional layer can be made of flexible materials (such as geotextiles) with certain permeability and elastic wave transmission capability to ensure that the infiltration time through the artificial interface functional layer in Model A is consistent with the infiltration time through the overburden layer on the virtual layered interface in Model B. The thickness of the artificial interface in Model A is determined based on the infiltration velocity derived from Darcy's law of one-dimensional seepage.

Claims

1. A method for preparing a heterogeneous model for a centrifuge shaking table test, characterized in that, Includes the following steps: Step S1: First, obtain the depth of the test site. H p And the thickness of the liquefiable soil layer in the prototype site h s p The thickness of the overburden layer in the prototype site is obtained by processing it according to the following formula. h t p : h t p = H p - h s p Step S2: Next, determine the centrifugal acceleration 'a' for the centrifuge shaking table test, a = N * g, where N represents the preset scaling ratio during the centrifuge shaking table test, and g represents the gravitational acceleration. Also, obtain the thickness of the liquefiable soil layer unit in the experimental model. h k m ; Step S3: Next, based on the thickness of the overburden layer in the prototype site... h t p Obtain the stress σ of the overburden layer in the prototype site. v The stress σv is obtained according to the following formula: s v =p 土 g h t p ; Density calibration tests were conducted on the pre-selected heterogeneous materials to obtain their material density ρ. Then, the specific weight γ of the heterogeneous materials was obtained using the following formula: γ=ρ*g; Then, the thickness of the overlying heterogeneous material layer of the experimental model is obtained based on the material density γ. h t m The thickness h t m Obtained using the following formula: h t m =s v / (N*γ); Step S4: Based on the above steps, determine the thickness of the liquefiable soil layer unit in the model. h k m and the thickness of the overlying heterogeneous material layer h t m The target experimental model is prepared layer by layer, and then the prepared target experimental model is used to conduct simulation tests on the prototype site to obtain the acceleration, pore water pressure and shear wave velocity of the soil layer in the prototype site.

2. The method for preparing a heterogeneous model for a centrifuge shaking table test according to claim 1, characterized in that: In step S2, the thickness of the liquefiable soil layer unit in the experimental model h k m The specific steps to obtain it are as follows: First, the liquefiable soil layer in the prototype site was divided into... n The prototype liquefiable soil layer unit was first constructed, and then the thickness of each prototype liquefiable soil layer unit was measured. Then, the thickness of the liquefiable soil layer unit in the experimental model was obtained according to the following formula. k Thickness of liquefiable soil layer unit h k m : h k m = h k p / N in, k This indicates the ordinal number of the prototype liquefiable soil layer unit. n This indicates the total number of layers in the prototype liquefiable soil unit. h k p Indicates the first k The thickness of the prototype liquefiable soil layer unit.

3. The method for preparing a heterogeneous model for a centrifuge shaking table test according to claim 1, characterized in that: The specific steps of S4 are as follows: Step S41: First, take the soil of the liquefiable soil layer in the prototype site as the calibration soil. In the indoor laboratory, use the calibration soil as raw material to pour the liquefiable soil layer in layers to form the experimental model. Step S42: Pour an artificial interface functional layer onto the upper surface of the liquefiable soil layer of the experimental model to form the initial model; Step S43: Place the initial model inside a vacuum chamber, and then continuously inject a viscous liquid with a viscosity N times that of water into the initial model, while simultaneously saturating the initial model with soil. If the liquid surface formed after the viscous liquid is injected is flush with the upper surface of the artificial interface functional layer, it indicates that the soil saturation is complete. Stop injecting the viscous liquid and then remove the initial model from the vacuum box. If the liquid level formed after the injection of viscous liquid is lower than the upper surface of the artificial interface functional layer, it indicates that the soil saturation is not complete, and the injection of viscous liquid should continue. Step S44: After the initial model is saturated, heterogeneous material is continuously poured onto the upper surface of the initial model, forming a heterogeneous material layer on the upper surface of the initial model. Simultaneously, sensors are embedded within the heterogeneous material layer. When the thickness of the heterogeneous material layer reaches the thickness of the overlying heterogeneous material layer... h t m The casting of heterogeneous materials was stopped at a certain time, and the initial model with the heterogeneous material layer cast at this time was used as the target experimental model. Finally, the prepared target experimental model was used to simulate the prototype site to be tested in order to obtain the acceleration, pore water pressure and shear wave velocity of the prototype site.

4. The method for preparing a heterogeneous model for a centrifuge shaking table test according to claim 3, characterized in that: In step S41, the specific steps for pouring the liquefiable soil layer of the experimental model are as follows: pour the liquefiable soil layer according to the thickness of each of the n experimental model units. n The experimental model consists of liquefiable soil layer units, with sensors embedded between adjacent liquefiable soil layer units. The liquefiable soil layer of the experimental model mainly comprises... n The experimental model is formed by stacking liquefiable soil layers in sequence.

5. The method for preparing a heterogeneous model for a centrifuge shaking table test according to claim 3, characterized in that: In step S42, the thickness h of the artificial interface functional layer is obtained according to the following formula: ； in, ρ 异 ρ is the density of the heterogeneous material layer overlying the experimental model, and ρ′ is the effective density of the liquefiable soil layer in the experimental model. k m The permeability coefficient of the artificial interface functional layer. k p denoted as the permeability coefficient of the heterogeneous material layer covering the experimental model.

6. The method for preparing a heterogeneous model for a centrifuge shaking table test according to claim 3, characterized in that: The artificial interface functional layer is designed with a serrated shape, which allows the liquefiable soil layer and the heterogeneous material layer of the experimental model to be tightly bonded together through the serrated artificial interface functional layer.

7. The method for preparing a heterogeneous model for a centrifuge shaking table test according to claim 3, characterized in that: In step S44, the acceleration, pore water pressure, and shear wave velocity of the prototype site are obtained in the following ways: First, a basic soil experiment is conducted on the target experimental model to obtain the acceleration, pore water pressure, and shear wave velocity of the target experimental model. The acceleration of the prototype site is the acceleration of the target experimental model / N, the pore water pressure of the prototype site is the same as that of the target experimental model, and the shear wave velocity of the prototype site is the same as that of the target experimental model.

8. The method for preparing a heterogeneous model for a centrifuge shaking table test according to claim 3, characterized in that: The sensor in step S4 is an acceleration sensor, a pressure sensor, or a portable bending element sensor.

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