Vacuum preloading plastic drainage plate foundation lateral deformation prediction method

Abstract

The invention discloses a method for predicting lateral deformation of a vacuum preloading plastic drainage plate foundation. Comprising the steps of calculating initial undrained shear strength of foundation soil, calculating dimensionless characteristic parameters, calculating a representative stress ratio, calculating a ratio of the representative stress ratio to a static soil pressure coefficient, calculating a ratio of corrected horizontal strain to one-dimensional compression strain under vacuum preloading, and calculating one-dimensional compression strain under vacuum preloading. Calculating corrected horizontal strain; and calculating lateral deformation of the foundation. According to the method, the relational graph of the stress ratio and the characteristic parameters and the quantitative relational graph of the corrected horizontal strain / the one-dimensional compression strain of the soil body and the representative stress ratio of the soil body / the static soil pressure coefficient of the soil body are taken as main bodies, so that the lateral deformation of the plastic drainage plate foundation under the vacuum preloading can be quickly calculated; and reference is provided for related design of the vacuum preloading treatment drainage plate foundation.

Description

Technical Field

[0001] The present invention belongs to the technical field of soft soil foundation treatment, and particularly relates to a method for predicting the lateral deformation of a vacuum preloading plastic drainage board foundation. Background Art

[0002] When treating a soft soil foundation by using the vacuum preloading combined with the plastic drainage board method, since the vacuum pressure is similar to the isotropic consolidation stress, it will cause the soil body to produce settlement and inward lateral deformation. The research and analysis of ground settlement have been relatively in-depth, and the technical methods are also relatively mature; the research on the inward lateral deformation is not complete enough, and the inward lateral deformation will cause surface cracking, and in severe cases, it will affect the integrity of the foundation, thus affecting the safety of surrounding buildings. Therefore, accurately predicting and analyzing the lateral deformation of the soft soil foundation has important guiding significance for engineering design and construction.

[0003] However, the current prediction method for the lateral deformation of the drainage board foundation under vacuum preloading is proposed based on the assumption that the volume strain of the soil body under the vacuum preloading condition is equal to the volume strain of the soil body under the one-dimensional condition. The rationality of its assumption conditions remains to be discussed, and it does not comprehensively reflect the influence of the soil stress state on the lateral deformation of the foundation. The patents with the patent numbers CN202410607768.9 and CN202310286028.5, titled "Method for Predicting Lateral Deformation of a Surcharge Preloading Plastic Drainage Board Foundation" and "Method for Predicting Lateral Deformation of a Vacuum Combined Surcharge Preloading Drainage Board Foundation" respectively, disclosed by the inventor in the early stage, although they can predict the lateral deformation of the drainage board foundation, still have the following deficiencies: First, their applicable ranges are relatively narrow, only applicable to the working conditions of surcharge preloading and vacuum combined surcharge preloading respectively, and both cannot be applied to the prediction and calculation of the lateral deformation of the drainage board foundation under vacuum preloading; Second, in the process of establishing the prediction method, it is not considered that the horizontal strain of the soil element obtained from the triaxial test of the unit body and the simulation of the unit body is not equal to the actual horizontal strain of the foundation soil. The horizontal strain of the soil body obtained based on the unit test or simulation under vacuum preloading and surcharge preloading is often greater than the actual horizontal strain of the foundation soil. Therefore, the horizontal strain of the soil element cannot accurately represent the horizontal strain of the foundation soil in the large-area vacuum preloading area; Due to the above influencing factors not being considered comprehensively enough, it increases the uncertainty of the prediction results of the existing methods.

[0004] In summary, it is necessary to propose a method that comprehensively considers the main influencing factors and can more accurately calculate the lateral deformation of the drainage board foundation under vacuum preloading. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for predicting the lateral deformation of a plastic drainage board foundation under vacuum preloading. This application is mainly based on the relationship diagram between the stress ratio and the characteristic parameter and the quantitative relationship diagram between the modified horizontal strain / one-dimensional compression strain of the soil and the stress ratio of the soil / the coefficient of earth pressure at rest of the soil, and can quickly calculate the lateral deformation of the plastic drainage board foundation under vacuum preloading, providing a reference for the relevant design of the drainage board foundation treated by vacuum preloading.

[0006] To this end, the method for predicting the lateral deformation of a drainage board foundation under vacuum preloading provided by the present invention includes the following steps:

[0007] S1. Calculate the initial undrained shear strength S of the foundation soil u0

[0008] S2. Calculate the dimensionless characteristic parameter β

[0009] According to the vacuum pressure P v , the undrained shear strength S of the soil u0 , the dimensionless parameter μ and the parameters related to the drainage consolidation of the drainage board foundation, the characteristic parameter β is calculated by the following formula:

[0010]

[0011] In the formula, t n = 1 day, without actual physical meaning, aiming to make β a dimensionless parameter, c h is the horizontal consolidation coefficient of the soil, r e is the equivalent radius of the influence area of the drainage board, P a is the standard atmospheric pressure; μ is a dimensionless parameter in the theory of radial drainage consolidation considering the drainage board spacing, smearing effect and well resistance;

[0012] S3. According to the characteristic parameter β calculated in step S2, referring to the β-K e relationship diagram, the soil stress ratio K e is calculated according to the following formula:

[0013] K e = -0.36841e (-β / 4.934) + 0.78487(9)

[0014] S4. Calculate the ratio K e of the stress ratio K e to the known coefficient of earth pressure at rest K0; e / K0;

[0015] S5. Under the condition of vacuum preloading, carry out multi-condition unit tests or simulation simulations to obtain multiple groups of horizontal strain ε h data of the soil unit, and for the horizontal strain ε hThe data is corrected to obtain the corrected horizontal strain ε of the drain board foundation h * Data:

[0016]

[0017] In the formula: ε h * is the corrected horizontal strain of the drain board foundation, and ξ is the correction coefficient;

[0018] The vertical strain ε under one-dimensional compression conditions v1 and the coefficient of earth pressure at rest K0 are used to normalize the data of the corrected horizontal strain ε h * and K e data, and the relationship between ε h * / ε v1 and K e / K0 is obtained through fitting analysis:

[0019] f(x) = 0.28942e (-x / 1.416) -0.14052(11)

[0020] In the formula, f(x) = ε h * / ε v1 ; x = K e / K0; ε h * is the corrected horizontal strain, and ε v1 is the one-dimensional compression strain;

[0021] S6. Calculate the one-dimensional compression strain ε under actual vacuum preloading v1 , as follows:

[0022]

[0023] In the formula, C c is the compression index, e0 is the initial void ratio, |P v | is the absolute value of the vacuum pressure, and σ′ vo is the initial vertical effective stress;

[0024] S7. Calculate the value of ε h * / ε v1 under actual vacuum preloading according to the relationship obtained in step S5, and at the same time, combined with the ε v1 value obtained in step S6, calculate the corrected horizontal strain ε h * under actual vacuum preloading;

[0025] S8. Calculate the lateral deformation of the drain foundation under actual vacuum preloading based on the corrected horizontal strain ε obtained in step 7 and the width B of the vacuum preloading area. h * Specifically, the specific expression of μ is as follows:

[0026]

[0027]

[0028] In the formula, r s is the radius of the smeared zone, r w is the equivalent radius of the drain, l is the length of the drain, q w is the drainage volume per unit time of the drain, k h is the horizontal permeability coefficient of the non-smeared zone, k s is the permeability coefficient of the smeared zone.

[0029] Specifically, for the plane strain condition, the horizontal strain under triaxial conditions needs to be converted into the horizontal strain under plane strain conditions according to Equation (14):

[0030]

[0031] In the formula, ε hp * is the horizontal strain of the soil under plane strain conditions, and ν is the Poisson's ratio of the soil.

[0032] Specifically, the calculation process of the initial undrained shear strength S u0 is as follows:

[0033] Calculate the undrained shear strength S of the soil according to the initial effective stress conditions and the soil property parameters through Equations (1)-(4): u0 :

[0034]

[0035] q = σ v ′0 - σ h ′0(3)

[0036]

[0037] In the formula, p' and q are the average effective stress and deviator stress of the soil, respectively; OCR is the overconsolidation ratio of the soil, σ′ vo is the initial vertical effective stress of the soil, σ′ h0 is the initial horizontal effective stress of the soil, C c is the compression index, C s is the swelling index, Λ is related to C c and C sThe relevant dimensionless parameter, where M is the slope of the critical stress state line of the soil mass.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The present invention comprehensively considers the influence of relevant parameters of drainage boards, soil consolidation characteristics, vacuum preloading conditions, etc. Taking the relationship diagram between the soil stress ratio K e and the characteristic parameter β and ε h * / ε v1 and K e / K0's quantitative relationship diagram as the main body, the given relationship diagram is relatively simple, avoiding the relatively complex analysis process in the existing graphical method. Using the method of the present invention, the lateral deformation of the drainage board foundation under vacuum preloading can be quickly calculated, providing a reference for the relevant design of the vacuum preloading plastic drainage board foundation.

[0040] 2. The method of the present invention takes into account that the horizontal strain of the soil element obtained from the triaxial test of the unit body and the simulation of the unit body is not equal to the actual horizontal strain of the foundation soil. The horizontal strain of the soil mass obtained based on the unit body test or simulation under vacuum preloading is often greater than the actual horizontal strain of the foundation soil. Therefore, during the establishment of the prediction method, based on the effective stress ratio of the soil mass, a reduction correction coefficient for mapping the horizontal strain of the unit body to the actual horizontal strain of the foundation soil is proposed, increasing the accuracy of the prediction result of the foundation lateral deformation.

[0041] In summary, the method of the present invention improves the deficiencies of the existing method in predicting the lateral deformation of the drainage board foundation under vacuum preloading. Moreover, it constructs the mapping relationship between the stress ratio and the dimensionless characteristic parameter with the stress ratio corresponding to the median point of the excess pore water pressure of the plastic drainage board foundation during the vacuum preloading consolidation stage, which is more representative. In addition, it takes into account that the horizontal strain of the soil mass obtained based on the unit body test or simulation under vacuum preloading is often greater than the actual horizontal strain of the foundation soil, thereby reducing the horizontal strain and making the prediction result more accurate and reliable. Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0043] Figure 1 is the relationship diagram between the soil stress ratio K e and the characteristic parameter β of the present invention;

[0044] Figure 2 is ε h / ε v1 With K e Quantitative relationship diagram with K0. Specific implementation mode

[0045] The following will combine the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] The method for predicting the lateral deformation of a plastic drainage board foundation under vacuum preloading provided by the present invention includes the following steps:

[0047] S1. According to the initial effective stress conditions (σ' h0 and σ' v0 ) and the soil property parameters (C c , C s and M), calculate the undrained shear strength S u0 of the soil through formulas (1)-(4):

[0048]

[0049] q = σ v ′0 - σ h ′0(3)

[0050]

[0051] In the formula, p' and q are the average effective stress and deviator stress of the soil respectively; OCR is the overconsolidation ratio of the soil, σ′ v0 is the initial vertical effective stress of the soil, σ′ h0 is the initial horizontal effective stress of the soil, C c is the compression index, C s is the swelling index, Λ is a dimensionless parameter related to C c and C s ;

[0052] M is the slope of the critical stress state line of the soil, and for the triaxial compression test, it can be calculated according to the following formula:

[0053]

[0054] Among them, is the effective internal friction angle of the soil.

[0055] S2. Calculate the dimensionless characteristic parameter β

[0056] The main factors affecting the lateral deformation and effective stress ratio of the drain board foundation under vacuum preloading include the vacuum pressure P v , the initial effective stress of the soil mass, and the consolidation parameters of the drain board foundation. Among them, the relevant consolidation parameters include the smear effect, well resistance effect, spacing of the drain board (PVD), size of the drain board, and consolidation coefficient of the soil mass. Existing radial drainage consolidation theories indicate that the radial consolidation of the drain board foundation is mainly controlled by the horizontal consolidation time factor (T h ), and its expression is:

[0057]

[0058] In the formula, c h is the horizontal consolidation coefficient of the soil mass; t is the consolidation time; r e is the equivalent radius of the influence area of the drain board; μ is a dimensionless parameter.

[0059] The above formula shows that, except for the consolidation time t, the consolidation of the drain board foundation is mainly determined by the horizontal consolidation coefficient of the soil mass (c h ), the radius of the soil element (i.e., the equivalent radius of the influence area of the drain board) r e , and the dimensionless parameter μ. The expression of the dimensionless parameter μ is:

[0060]

[0061] In the formula, r s is the radius of the smear zone, r w is the equivalent radius of the drain board (PVD), l is the length of the drain board, q w is the drainage volume per unit time of the drain board, k h is the horizontal permeability coefficient of the non-smear zone, and k s is the permeability coefficient of the smear zone. It can be seen from the above formula that the dimensionless parameter μ comprehensively considers the influences of the smear effect, well resistance effect, drain board spacing, and drain board size, while the consolidation coefficient c h can reflect the influence of the consolidation characteristics of the soil mass.

[0062] The basic theory of soil mechanics indicates that the initial effective stress of the soil mass largely determines its initial undrained shear strength (S u0 ), so S u0 can be used to reflect the influence of the initial effective stress of the soil mass. In addition, existing research shows that the lateral deformation and stress ratio of the drain board foundation are related to the 0.2 power of the ratio of the vacuum pressure P v to the standard atmospheric pressure (P a ). In this regard, the present invention combines the above main influencing factors (c h , μ, r e , S u0 , (P v / Pa ) 0.2 ) Integrate them to form a dimensionless parameter β, and the expression of β is as follows:

[0063]

[0064] In the formula, t n = 1 day, which has no actual physical meaning and is intended to make β a dimensionless parameter; P v is the vacuum pressure; P a is the standard atmospheric pressure.

[0065] S3. Refer to Figure 1 , according to the characteristic parameter β calculated in step S2, refer to the β-K e relationship diagram, and calculate the soil stress ratio K according to the following formula e :

[0066] K e = -0.36841e (-β / 4.934) + 0.78487(9)

[0067] S4. Based on the triaxial compression test with radial drainage, establish a finite element simulation model, carry out simulation calculations under multiple working conditions, and analyze the lateral deformation and stress state characteristics of the soil element body. A total of 16 simulation working conditions are calculated and analyzed. The inventor's research found that according to the analysis of the simulation calculation results, the horizontal strain of the soil element body under each working condition is not equal to the actual horizontal strain. The horizontal strain of the soil obtained based on the unit test or simulation under vacuum preloading is greater than the horizontal strain of the actual drain board foundation. Therefore, during the establishment of the prediction method, it is necessary to correct the horizontal strain ε h data of the soil element body to obtain the corrected horizontal strain ε h * . The correction coefficient ξ is 0.25K e , and this value is obtained by back-calculating the measured lateral deformation of the actual project. That is:

[0068]

[0069] In the formula, ξ is the correction coefficient. The value of the correction coefficient ξ is 0.25K e .

[0070] Under different soil properties and loading conditions, the value of K e will change accordingly, which means that the correction coefficient ξ will also change with the specific working conditions. The larger K e is, the stronger the vacuum preloading effect is, the more significant the horizontal preloading effect on the actual soil body is, and the correction coefficient ξ will increase accordingly. To form a lateral deformation prediction method applicable to different soft soils with universal significance, the vertical strain ε under one-dimensional compression conditions is respectively used v1and the coefficient of earth pressure at rest K0 on the corrected horizontal strain ε h * data and K e The data is normalized, and through fitting analysis, ε h * / ε v1 and K e / K0 have the following relationship:

[0071] f(x) = 0.28942e (-x / 1.416) -0.14052(11)

[0072] where f = ε h * / ε v1 ; x = K e / K0; ε h * is the corrected horizontal strain, and ε v1 is the one-dimensional compression strain.

[0073] S5. Refer to Figure 2 , according to the quantitative relationship diagram between ε h * / ε v1 and K e / K0, calculate ε h * / ε v1

[0074] S6. Calculate the one-dimensional compression strain ε v1 under vacuum preloading, as follows:

[0075]

[0076] where C c is the compression index, e0 is the initial void ratio, |P v | is the absolute value of the vacuum pressure, and σ′ v0 is the initial vertical effective stress.

[0077] S7. Calculate the value of ε h * / ε v1 under the actual vacuum preloading according to the relationship obtained in step S5, and at the same time, combined with the value of ε v1 obtained in step S6, calculate the corrected horizontal strain ε h * ;

[0078] S8. According to the corrected horizontal strain ε h *The lateral deformation of the drain board foundation is calculated according to the following formula considering the value and the width B of the vacuum preloading area:

[0079]

[0080] The proposed prediction method for the lateral deformation of the drain board foundation under vacuum preloading is obtained based on improved triaxial compression tests and numerical simulation analysis. Therefore, it can be directly applied to calculate the lateral deformation of the drain board foundation under vacuum preloading under triaxial conditions. However, in actual engineering, there are often engineering cases of drain board foundations under vacuum preloading that are approximately plane strain. Therefore, when applying the above method to solve the problem of calculating lateral deformation in such projects, the horizontal strain under triaxial conditions needs to be converted into the horizontal strain under plane strain conditions according to the following formula:

[0081]

[0082] In the formula, ε hp * is the horizontal strain of the soil under plane strain conditions, and ν is the Poisson's ratio of the soil.

[0083] It can be understood that referring to Figure 1 , in the β-K e relationship diagram drawn based on the above calculations, the coefficient of determination R e of the fitting curve in the figure is 0.989, which is greater than 0.98, indicating a good fitting effect. 2 =0.989 is greater than 0.98, and the fitting effect is good.

[0084] Compared with the prediction methods for the lateral deformation of the drain board foundation under vacuum surcharge preloading and the prediction method for the lateral deformation of the prefabricated vertical drain foundation under surcharge preloading proposed by the inventor in the early stage (Patent Nos.: CN202310286028.5, CN202410607768.9), the method of the present invention has the following essential differences:

[0085] 1. Different applicable ranges: The prediction method for the lateral deformation of the drain board foundation under vacuum surcharge preloading is applicable to the working condition of vacuum combined surcharge preloading. The prediction method for the lateral deformation of the prefabricated vertical drain foundation under surcharge preloading is applicable to the working condition of surcharge preloading. However, the method of the present invention is applicable to the working condition of vacuum preloading.

[0086] 2. Different selection of representative values of the stress ratio: The prediction method for the lateral deformation of the drain board foundation under vacuum surcharge preloading mainly calculates the stress ratio at the end of surcharge as the representative value K e by reading the excess pore water pressure value at the end of surcharge. The prediction method for the lateral deformation of the prefabricated vertical drain foundation under surcharge preloading is for the working condition of surcharge preloading alone, and analyzes the representative stress ratio K e *, the method of the present invention is aimed at the working condition of vacuum preloading alone, and analyzes the representative stress ratio K of the soil element based on the median point of the excess pore water pressure during the consolidation stage of vacuum preloading. e .

[0087] 3. The calculation of horizontal strain is different: the prediction method of the lateral deformation of the drain board foundation under vacuum-surcharge preloading and the prediction method of the lateral deformation of the plastic drain board foundation under surcharge preloading calculate the required horizontal strain based on the horizontal deformation of the soil mass output by the triaxial test simulation. The method of the present invention takes into account that the horizontal strain of the soil mass obtained based on the unit test or simulation under vacuum preloading is often greater than the horizontal strain of the actual foundation soil, and thus reduces and corrects the horizontal strain.

[0088] To verify the reliability of the method of the present application, the method of the present invention is respectively applied to the calculation of the lateral deformation in two actual engineering cases, comprehensively considering common engineering practices. Through verification and analysis, it shows that the predicted value of the lateral deformation is in good agreement with the measured value, and the predicted lateral deformation trend and curve are basically the same, indicating that the method can effectively predict the lateral deformation of the drain board foundation under vacuum preloading.

[0089] The following takes one of the engineering cases as an example for a brief description: This project is located in the Pudong area of Shanghai, west of Huadong Road and north of Chuanyang River. Table 1 lists the physical parameters of the soil layers. In the table, the OCR value is an assumed value, the c v value is back-calculated by fitting the measured compression curves of each soil layer, and the other parameter values are from the geological report. h is the thickness of the soil layer, e0 is the initial void ratio of the soil mass, γ t is the unit weight of the soil, c′ is the cohesion, is the effective internal friction angle of the soil mass, OCR is the overconsolidation ratio of the soil mass, C c is the compression index, C s is the swelling index, taking 0.1C c , c v is the vertical consolidation coefficient of the soil mass, k v is the vertical permeability coefficient of the soil mass. The horizontal consolidation coefficient c h is taken as 4c v ; the horizontal permeability coefficient k h of the soil mass is taken as 4 times the vertical permeability coefficient k v ; the value of k h / k s is taken as 4.0, and the coefficient of earth pressure at rest K0 of the soil mass is calculated according to .

[0090] The plastic drain boards are installed in a square pattern with a spacing of 1 m and a length of 20 m, and their drainage parameters are: q w = 0.274 m 3 / day, r w , rs and r e are taken as 0.026 m, 0.052 m and 0.565 m respectively. The vacuum is -85 kPa, the width of the preloading area is 90 m, and the vacuum attenuation rate within the length of the drainage board is 2 kPa / m.

[0091] Table 1 Physical parameters of soil

[0092]

[0093] After calculation, from Figure 1 the lateral deformation calculation values at the depths of 4 m and 9 m obtained from the analysis of the relationship between the soil stress ratio K e and the characteristic parameter β are 201 mm and 107 mm respectively (the lateral deformation is towards the inner side of the subgrade), both of which are between the measured values of 190 - 208 mm and 101 - 115 mm, indicating that the calculated values are in good agreement with the measured values.

[0094] The above embodiments are merely examples clearly illustrating the present invention, rather than limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for predicting the lateral deformation of a foundation with vacuum preloading plastic drainage plates, characterized in that It includes the following steps: S1. Calculate the initial undrained shear strength S of the foundation soil u0 S2. Calculate the dimensionless characteristic parameter β According to the vacuum pressure P v , the undrained shear strength S of the soil mass u0 , the dimensionless parameter μ and the parameters related to the drainage consolidation of the vertical drain foundation, the characteristic parameter β is calculated by the following formula: where t n = 1 day, without actual physical meaning, aiming to make β a dimensionless parameter, c h is the horizontal consolidation coefficient of the soil mass, r e is the equivalent radius of the influence area of the drain board, P a is the standard atmospheric pressure; μ is a dimensionless parameter considering the drain board spacing, smear effect and well resistance in the radial drainage consolidation theory; S3. According to the characteristic parameter β calculated in step S2, referring to the β-K e relationship diagram, calculate the soil stress ratio K according to the following formula e : K e = -0.36841e (-β / 4.934) +0.78487(9) S4. Calculate the stress ratio K e according to the value of K e and the ratio K e / K0 of the known coefficient of earth pressure at rest K0; S5. Under the condition of vacuum preloading, carry out multi-condition unit tests or simulation simulations to obtain multiple groups of horizontal strain ε of soil unit bodies h data, and correct the horizontal strain ε h data of soil unit bodies to obtain the corrected horizontal strain ε h * data of the drain board foundation: where: ε h * is the modified horizontal strain of the drain board foundation, and ξ is the correction coefficient; Adopt the vertical strain ε under one-dimensional compression conditions v1 and the coefficient of earth pressure at rest K0 for the modified horizontal strain ε h * data and K e Normalize the data and obtain the relationship between ε h * / ε v1 and K e / K0 through fitting analysis: f(x) = 0.28942e (-x / 1.416) -0.14052(11) where f(x) = ε h * / ε v1 ; x = K e / K0; ε h * is the corrected horizontal strain, and ε v1 is the one-dimensional compression strain; S6. Calculate the one-dimensional compression strain ε under vacuum preloading v1 , as shown in the following formula: where C c is the compression index, e0 is the initial void ratio, |P v | is the absolute value of the vacuum pressure, and σ′ vo is the initial vertical effective stress; S7. Calculate the ε value under the actual vacuum preloading according to the relational expression obtained in step S5, and at the same time, combine with the ε value obtained in step S6 to calculate the corrected horizontal strain ε under the actual vacuum preloading; h * / ε v1 value, and at the same time, combine with the ε v1 value obtained in step S6 to calculate the corrected horizontal strain ε h * ; S8. Calculate the lateral deformation of the drain board foundation under actual vacuum preloading based on the corrected horizontal strain ε h * value obtained in Step 7 and the width B of the vacuum preloading area.

2. The method for predicting the lateral deformation of a vacuum preloading plastic drain foundation according to claim 1, wherein: The specific expression of μ is as follows: Wherein, r s is the radius of the smearing zone, r w is the equivalent radius of the drain board, l is the length of the drain board, q w is the drainage volume per unit time of the drain board, k h is the horizontal permeability coefficient of the non-smearing zone, k s is the permeability coefficient of the smearing zone.

3. The method for predicting the lateral deformation of a vacuum preloading plastic drain foundation according to claim 1, characterized in that: For the plane strain condition, it is necessary to convert the horizontal strain under the triaxial condition into the horizontal strain under the plane strain condition according to Equation (14): where ε hp * is the horizontal strain of the soil under plane strain conditions, and ν is the Poisson's ratio of the soil.

4. The method for predicting the lateral deformation of a vacuum preloading plastic drain foundation according to claim 1, wherein: Initial undrained shear strength S u0 The calculation process is as follows: According to the initial effective stress conditions and the soil property parameters, the undrained shear strength S of the soil is calculated by equations (1)-(4). u0 : q = σ v ′0 - σ h ′0(3) Wherein, p' and q are the average effective stress and deviator stress of the soil mass respectively; OCR is the over-consolidation ratio of the soil mass, σ′ v0 is the initial vertical effective stress of the soil mass, σ′ h0 is the initial horizontal effective stress of the soil mass, C c is the compression index, C s is the swelling index, Λ is a dimensionless parameter related to C c and C s and M is the slope of the critical stress state line of the soil mass.

5. The method for predicting the lateral deformation of a vacuum preloading plastic drainage board foundation according to claim 1, characterized in that: Calculate the lateral deformation of the drain board foundation according to the following formula:

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