Estimation and evaluation method and system for subgrade settlement deformation at the intersection of fill and cut section during operation under vehicle load

Abstract

The present invention discloses a method and system for estimating and evaluating the settlement deformation of the embankment at the intersection of excavation and filling during operation under vehicle load. The specific estimating method comprises the following steps: sampling the excavation section and the filling section at the intersection of excavation and filling of the embankment; performing static triaxial tests and dynamic triaxial tests on the samples, and obtaining the deformation modulus E of the embankment soil under static load through the static triaxial tests. t and the tangent Poisson's ratio ν t ; The damping ratio λ of the embankment soil under vehicle load is obtained through dynamic triaxial test d ; Establish a two-dimensional model of the fill-cut junction section of the roadbed during the operation period, and obtain the vertical stress σ corresponding to each node 1i , lateral stress σ 3i , the dynamic stress σ′ corresponding to each node di ; Then the total settlement deformation of any vertical section in the longitudinal length direction of the roadbed is obtained. The present invention provides a method for estimating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load, which fully considers the deformation of the roadbed soil and can more accurately and efficiently estimate the settlement deformation of the roadbed at the intersection of fill and cut.

Description

Technical Field

[0001] The invention belongs to the technical field of roadbed engineering, and relates to a method and system for estimating and evaluating the settlement deformation of a roadbed at a filling and cutting junction section during operation under vehicle load. Background Art

[0002] At present, the problem of differential settlement of roadbed is a common highway disease, especially in the hot and humid southern region of my country. The foundation soil in southern my country is mainly special soil foundation, which has the characteristics of high water content, low strength and high compressibility. During the operation period of the highway, the foundation soil is prone to consolidation and shear failure, resulting in obvious differential settlement after construction and lateral cracking, which greatly shortens the service life of the highway and poses a great hidden danger to road driving safety.

[0003] There are many existing methods for evaluating differential settlement of roadbeds at the junction of cut-fill and fill sections, which are mainly concentrated in the following three aspects: (1) Predicting the settlement and deformation of the roadbed at the junction of cut-fill and fill sections during the operation period through on-site monitoring during the construction period, and further effectively controlling differential settlement. (2) Predicting the settlement and deformation of the roadbed at the junction of cut-fill and fill sections during the operation period through a theoretical combination model, and comprehensively evaluating the differential settlement of the roadbed at the junction of cut-fill and fill sections based on on-site settlement monitoring data; (3) Preventing and controlling differential settlement of the roadbed at the junction of cut-fill and fill sections through methods such as pavement overlay and grouting foundation reinforcement. Although the above methods can effectively evaluate and control differential settlement of roadbeds at the junction of cut-fill and fill sections, they have many shortcomings and deficiencies:

[0004] First, long-term observation is susceptible to external interference and is costly. The monitoring period is during the highway operation period, which poses a safety hazard to the monitoring staff.

[0005] Second, the prediction accuracy of the theoretical combination model is low, and the actual deformation of the roadbed soil is not taken into account. The measured differential settlement value is quite different from the actual value, which makes it difficult to use accurate methods to prevent and control differential settlement of the roadbed.

[0006] Therefore, it is particularly important to design a method for estimating and evaluating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load, especially in the field of roadbed engineering. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a method for estimating the settlement deformation of the roadbed at the junction of fill and cut during the operation period under the action of vehicle load, which comprehensively considers the deformation of the roadbed soil and can more accurately and efficiently estimate the settlement deformation of the roadbed at the junction of fill and cut, thus solving the problems existing in the prior art.

[0008] Another object of the present invention is to provide a method for evaluating roadbed settlement.

[0009] Another object of the present invention is to provide a system for estimating the settlement and deformation of the roadbed at the intersection of fill and cut during operation under the action of vehicle load.

[0010] The technical solution adopted by the present invention is a method for estimating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load, which is specifically carried out in the following steps:

[0011] S1, sampling at the excavation section and filling section at the junction of the embankment and fill;

[0012] S2, static triaxial test and dynamic triaxial test are performed on the samples in step S1, and the test conditions of different confining pressure, compaction degree and water content are set in the test. The deformation modulus E of the embankment soil under static load is obtained through static triaxial test. t and the tangent Poisson's ratio ν t ; The damping ratio λ of the embankment soil under vehicle load is obtained through dynamic triaxial test d ;

[0013] S3, using numerical simulation software to establish a two-dimensional model of the roadbed at the intersection of the fill and cut section during the operation period, including the cut section and the fill section; meshing the two-dimensional model, and numbering the nodes in any vertical section from top to bottom, where i represents the node number; the deformation modulus E obtained in step S2 is t and the tangent Poisson's ratio ν t As input parameters, the vertical stress σ corresponding to each node is obtained 1i , lateral stress σ 3i ; The deformation modulus E obtained in step S2 t , damping ratio λ d As the input parameter, the dynamic stress σ′ corresponding to each node is obtained di ;

[0014] S4, the vertical stress σ of each node in the excavation section and the filling section 1i , lateral stress σ 3i Substitute them into the corresponding permanent strain model under the action of dynamic load, obtain the strain of each node under the action of dynamic load, and obtain the settlement value of a certain vertical section of the fill section and the excavation section of the fill-excavation junction section under the action of dynamic load according to the corresponding strain;

[0015] S5, the vertical stress σ of each node in the excavation section and the filling section 1i , lateral stress σ 3i Substitute into the corresponding dynamic elastic modulus model to obtain the dynamic elastic modulus E of each node di , combined with the dynamic stress corresponding to each node, the strain value of each node under the simultaneous action of dynamic load and static load is obtained, and then according to the corresponding strain value, the settlement value of a certain vertical section of the fill section and the excavation section of the fill-excavation junction roadbed under the simultaneous action of static load and dynamic load is obtained respectively;

[0016] S6, based on the superposition of unit node settlement, the two settlement values ​​of the same vertical section are added together to obtain the total settlement deformation of any vertical section in the longitudinal length direction of the roadbed.

[0017] Furthermore, the step S1 is specifically as follows: on-site sampling is carried out in the excavation section at the junction of the embankment excavation and fill section; original soil is taken from the embankment fill section and samples are prepared by static pressure method; impurities are removed from the excavation section samples and sealed with plastic wrap to keep the samples in the original state of the soil; impurities are removed from the fill section soil samples, air-dried, sieved, and samples are prepared by static pressure method, and the sample size is consistent with that of the excavation section samples.

[0018] Furthermore, in step S2, the static triaxial test is carried out by the drainage consolidation method, the confining pressure is set to 10 kPa to 50 kPa, the compaction degree of the filling section is set to 90% to 96%, and the consolidation degree of the excavation section is set to U t Set to 70%, 80%, 90%, 100%, the excavation section uses the natural moisture content, and the filling section uses the optimal moisture content.

[0019] Furthermore, in step S4, the permanent strain model of the roadbed under the dynamic load of the filling section is shown in formula (7-1), and the permanent strain model of the roadbed under the dynamic load of the excavation section is shown in formula (7-2);

[0020]

[0021]

[0022] Among them, k5, k6, k7, k8, k9, k 10 , b2, b3 are test parameters, ε p is the initial plastic strain of the fill section, e is a constant, P a is the standard atmospheric pressure; ε 1di Indicates the permanent strain of the roadbed under the dynamic load of the fill section; k'5, k'6, k'7, k'8, k'9, k' 10 , b'2, b'3 are test parameters, ε' p is the initial plastic strain of the excavation section, ε′ 1di represents the permanent strain of the roadbed under the dynamic load of the excavation section; σ 11 represents the major principal stress of the soil in the fill section, σ 31 represents the minor principal stress of the soil in the fill section, σ 11 / σ 31 represents the stress ratio of the fill section soil, ω1 represents the water content of the fill section soil, K represents the compaction degree of the fill section soil; σ 12 represents the major principal stress of the soil in the excavation section, σ 32 represents the minor principal stress of the soil in the excavation section, σ12 / σ 32 represents the stress ratio of the soil in the excavation section, and ω2 represents the moisture content of the soil in the excavation section;

[0023] The vertical stress σ of each node in the fill section 1i , lateral stress σ 3i Substitute into formula (7-1) to calculate the strain ε of each node under dynamic load 1di , calculate the average strain value of the adjacent upper and lower nodes of the vertical section, and obtain the average strain value between the adjacent upper and lower nodes. Add the average strain value between the adjacent upper and lower nodes and divide it by the total number of node segments n of the vertical section to obtain It represents the average strain value of the vertical section of the roadbed under dynamic load;

[0024] The settlement value S between the two adjacent upper and lower nodes on the vertical section under dynamic load is calculated by formula (8): 1f :

[0025]

[0026] Among them, h f represents the length between the upper and lower nodes of the fth node segment, f = 1, 2, ... n; then the settlement value S of a certain vertical section of the fill section roadbed at the fill-cut junction under the action of dynamic load is calculated by formula (9): 1x , x represents a point on the longitudinal length X of the roadbed, that is, the position of the vertical section on the X-axis;

[0027]

[0028] The vertical stress σ of each node in the excavation section 1i , lateral stress σ 3i Substitute it into formula (7-2) and follow the other steps to find the settlement value S′ of a vertical section of the excavation section of the fill-excavation junction under the action of dynamic load. 1x .

[0029] Furthermore, in step S5, the soil dynamic elastic modulus model of the filling section is shown in formula (6-1), and the soil dynamic elastic modulus model of the excavation section is shown in formula (6-2);

[0030]

[0031]

[0032] Among them, k1, k2, k3, k4, b1 are test parameters, P a is the standard atmospheric pressure, E0 is the initial dynamic elastic modulus of the filling section, E 2drepresents the dynamic elastic modulus of the soil in the fill section, e is a constant; k'1, k'2, k'3, k'4, b'1 are test parameters, P a is the standard atmospheric pressure, E'0 is the initial dynamic elastic modulus of the excavation section, and E' 2d represents the dynamic elastic modulus of the excavation section, U t Indicates the degree of consolidation of the soil in the excavation section;

[0033] The vertical stress σ corresponding to each node of the filling section obtained in step S3 is 1i , lateral stress σ 3i Substituting into formula (6-1), the dynamic elastic modulus E of each node is calculated. 2di ; The stress σ of each node under the simultaneous action of dynamic load and static load is calculated by formula (10): di :

[0034] σ di =σ 1i +σ′ di (10)

[0035] The stress σ di Substituting into formula (11), we can obtain the strain value ε of each node under the simultaneous action of dynamic load and static load: 2di :

[0036] ε 2di =σ di / E di (11)

[0037] According to the strain values ​​ε of the adjacent upper and lower nodes of the vertical section 2di Calculate the average value to obtain the average strain between the two adjacent upper and lower nodes. Add the average strain between the two adjacent upper and lower nodes and divide it by the total number of segments n to obtain It represents the average strain value of the vertical section of the roadbed under the simultaneous action of dynamic load and static load;

[0038] The settlement value S between the two adjacent upper and lower nodes on the vertical section under the simultaneous action of static load and dynamic load is calculated by formula (12): 2f :

[0039]

[0040] In the formula, h f represents the length between the upper and lower nodes of the fth node segment, f = 1, 2, ... n; then the settlement value S of a certain vertical section of the fill section roadbed at the fill-cut junction under the simultaneous action of static load and dynamic load is calculated by formula (13): 2x :

[0041]

[0042] The vertical stress σ of each node in the excavation section 1i , lateral stress σ 3i Substitute it into formula (6-2), and follow the same steps to find the settlement value S′ of a certain vertical section of the excavation section of the fill-excavation junction under the simultaneous action of static load and dynamic load. 2x .

[0043] Furthermore, in step S2, the deformation modulus E t , Tangent Poisson's ratio ν t The Duncan-Zhang hyperbolic model is used to fit the experimental data, as shown in formula (1):

[0044]

[0045] Where P a is the standard atmospheric pressure, K and n are experimental constants, c is the cohesion, and φ is the internal friction angle; is the center of the circle, The method and formula for drawing the drained consolidation Mohr stress circle and strength envelope on the τ-σ plane with radius τ f =σtanφ+c to calculate the parameters c and φ; τ f is the shear strength of soil, σ is the normal stress on the shear sliding surface;

[0046] σ 1f represents the ultimate major principal stress, σ 3f represents the limiting minor principal stress, σ3 represents the minor principal stress, σ1 represents the major principal stress, R f represents the destruction ratio;

[0047]

[0048] Where (σ1-σ3) ult is the limit deviation stress, (σ1-σ3) f is the peak value of the deviatoric stress;

[0049]

[0050] Where G, F, and D are material constants.

[0051] Furthermore, in step S2, the damping ratio λ d It is obtained by the hysteresis curve method and calculated according to formula (5);

[0052]

[0053] Where ΔF is the area of ​​the hysteresis curve, and F is the area of ​​the triangle formed by the point on the hysteresis curve where the horizontal axis reaches the maximum value, the intersection of the perpendicular line from this point and the horizontal axis, and the origin.

[0054] A method for evaluating roadbed settlement is based on the above-mentioned method for estimating roadbed settlement deformation at the intersection of fill and cut during operation under vehicle load, specifically:

[0055] The maximum settlement deformations of the excavation section and the filling section of the roadbed at the junction of excavation and fill during the operation period are compared, and the larger one is compared with the standard deformation design value. If the maximum settlement deformation value is greater than the standard deformation design value, the roadbed does not meet the standard requirements; if the maximum settlement deformation value is less than the standard deformation design value, the roadbed meets the standard requirements.

[0056] A method for evaluating roadbed settlement is based on the above-mentioned method for estimating roadbed settlement deformation at the intersection of fill and cut during operation under vehicle load, specifically:

[0057] The maximum node strain value ε of the top surface of the roadbed under the simultaneous action of dynamic load and static load calculated in step S5 2dimax Compared with the standard strain value of cement concrete water-stable base in the specification, if ε 2dimax If ε is greater than the design strain value, it does not meet the specification requirements; 2dimax If it is less than the design strain value, it meets the specification requirements.

[0058] A system for estimating the settlement deformation of the filling and cutting junction section of the roadbed during the operation period under the action of vehicle loads, including a test system, wherein the test system includes a static triaxial test and a dynamic triaxial test, which are used to provide relevant calculation parameters for the numerical simulation system: the deformation modulus E of the soil in the filling section and the cutting section under the action of static loads; t , Tangent Poisson's ratio ν t and the damping ratio λ d ;

[0059] Numerical simulation system, used to establish a two-dimensional model of the cut-fill junction section of the roadbed during operation, calculate and derive the vertical stress σ corresponding to each node 1i , lateral stress σ 3i , dynamic stress σ′ di ;

[0060] Differential settlement prediction system is used to estimate the vertical stress σ 1i , lateral stress σ 3i , permanent strain model under dynamic load, dynamic elastic modulus model, dynamic stress σ′ corresponding to each node di The total settlement deformation of any vertical section in the longitudinal length direction of the roadbed is obtained.

[0061] The beneficial effects of the present invention are:

[0062] 1. The estimated roadbed settlement deformation of the present invention includes the roadbed deformation under static load (elastic deformation), the roadbed deformation under dynamic load (dynamic deformation) and the deformation caused by time change (creep deformation), which fully considers the deformation of the roadbed soil, effectively prevents road surface cracking, and solves the problem that the roadbed settlement calculation in the prior art only considers the single variable of elastic deformation or dynamic deformation, resulting in inaccurate roadbed settlement calculation.

[0063] 2. The present invention provides relevant calculation parameters for numerical simulation through dynamic and static triaxial tests. The test conditions of the dynamic triaxial test and the static triaxial test correspond to each other, fully considering the influence of vehicle load on the actual deformation of the soil and the influence of soil deadweight on the differential settlement of the roadbed at the junction of fill and excavation during the operation period, which is closer to the actual situation and has higher accuracy.

[0064] 3. The present invention is composed of a test system, a numerical simulation system, and a differential settlement evaluation system. It integrates tests and numerical simulations, and can consider the actual conditions of the subgrade soil at the junction of fill and excavation in many aspects. By comparing the total settlement deformation value with the standard value, and comparing the strain value of the subgrade top surface with the strain value of the pavement material, it can effectively and comprehensively evaluate the differential settlement of the subgrade at the junction of fill and excavation, thereby saving costs, time and effort. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0066] Figure 1 is a flow chart of an embodiment of the present invention.

[0067] Figure 2 This is a grid division diagram in an embodiment of the present invention. DETAILED DESCRIPTION

[0068] The following will be combined with 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0069] The basic concept of the embodiment of the present invention is as follows:

[0070] At present, the research on roadbed settlement deformation mainly focuses on the study of embankment settlement deformation under layered loading. The study of embankment settlement deformation under layered loading adopts the modulus reduction method, that is, the modulus of the soil body is reduced accordingly, and the amount of settlement deformation of the roadbed is reflected by the reduction coefficient. Few people have studied the post-construction settlement deformation of the intersection section of the roadbed during the operation period under dynamic loads. The reasons are: (1) During the operation period of the roadbed, it is impossible to fully understand the real-time condition of the soil inside the roadbed; (2) At present, the stress and strain of the specimen can only be tested through dynamic triaxial tests to calculate the deformation of the local soil. The settlement deformation of the entire roadbed can only be obtained through model prediction, and the prediction error is large.

[0071] The existing technology for calculating settlement deformation only considers the elastic deformation or dynamic deformation of the roadbed soil, but does not consider the creep deformation of the roadbed soil over time; the dynamic deformation cannot be calculated directly, and is usually calculated by extracting the stress-strain model under dynamic load with the help of dynamic triaxial test of the soil, which has large errors; the roadbed will undergo deformation characteristics over time (called creep) during the operation period. Compared with the elastic deformation of the roadbed soil, the creep of the roadbed soil is smaller, but it cannot be ignored. The creep of the roadbed soil is also one of the important factors leading to roadbed cracking. Therefore, the measured differential settlement value is quite different from the actual value.

[0072] The stress state of the subgrade soil at the junction of fill and cut is more complicated than that of other subgrades, with uneven force, obvious differential settlement after construction, and serious lateral cracking. It is necessary to comprehensively consider elastic deformation, dynamic deformation, and creep deformation to estimate the subgrade settlement. Mastering the subgrade settlement characteristics at the junction of fill and cut is of great significance to the subsequent safe and smooth operation of the road.

[0073] Embodiment 1,

[0074] A system for estimating the subsidence deformation of a roadbed at a filling-cut junction section during operation under vehicle load, comprising a test system, a numerical simulation system, and a differential settlement estimation system;

[0075] The test system includes static triaxial test and dynamic triaxial test, which are used to provide relevant calculation parameters for the numerical simulation system: deformation modulus E of the soil in the filling section and the excavation section under static load t , Tangent Poisson's ratio ν t and the damping ratio λ d ;

[0076] Numerical simulation system, used to establish a two-dimensional model of the cut-fill junction section of the roadbed during operation, calculate and derive the vertical stress σ corresponding to each node 1i , lateral stress σ 3i , dynamic stress σ′ di ;

[0077] Differential settlement prediction system is used to estimate the vertical stress σ1i , lateral stress σ 3i , permanent strain model under dynamic load, dynamic elastic modulus model, dynamic stress σ′ corresponding to each node di The total settlement deformation of any vertical section in the longitudinal length direction of the roadbed is obtained.

[0078] Embodiment 2,

[0079] A method for estimating the settlement deformation of a roadbed at a filling-cut junction section during operation under vehicle load is specifically performed in the following steps:

[0080] S1, on-site sampling is carried out at the excavation section at the junction of the embankment and fill excavation. It refers to cylindrical specimens with a diameter of D = 100mm and a height of h = 200mm. The original soil, i.e., loose soil samples, are taken from the embankment fill section. Determine the appropriate location for sampling in the fill section and the excavation section. The appropriate location refers to the road section with differential settlement, such as the roadbed at the junction of the embankment and fill excavation.

[0081] The excavation section samples are cleaned of impurities and sealed with plastic wrap to keep the samples in the original state of the soil.

[0082] The soil samples of the filling section are cleaned of impurities, air-dried, passed through a 5mm geosieve, and sampled using the static pressure method. The sample size is consistent with that of the excavation section sample; the sample size is diameter D = 100mm, height h = 200mm.

[0083] S2, a static triaxial test is performed on the sample obtained in step S1, and different test conditions such as confining pressure, compaction degree, and water content are set in the test to obtain the strength parameter 1 of the embankment soil under static load, that is, the deformation modulus E of the soil under static load. t and the tangent Poisson's ratio ν t .

[0084] The static triaxial test was carried out using the drainage consolidation method. The confining pressure was set to 10kPa~50kPa, the compaction degree of the fill section was set to 90%~96%, and the consolidation degree of the excavation section was set to U t (Take clay as an example) Set it to 70%, 80%, 90%, 100%, the excavation section uses the natural moisture content, and the filling section uses the optimal moisture content;

[0085] Deformation modulus E t , Tangent Poisson's ratio ν t The Duncan-Zhang hyperbolic model is used to fit the experimental data, as shown in formula (1):

[0086]

[0087] In the formula, p a is atmospheric pressure, p a=101.4kPa or approximately equal to 100kPa, K, n are test constants, c is cohesion, φ is internal friction angle; is the center of the circle, The method and formula for drawing the drained consolidation Mohr stress circle and strength envelope on the τ-σ plane with radius τ f =σtanφ+c to calculate the parameters c and φ; τ f is the shear strength of soil, σ is the normal stress on the shear sliding surface;

[0088] σ 1f represents the ultimate major principal stress, σ 3f represents the limiting minor principal stress, σ3 represents the minor principal stress, σ1 represents the major principal stress, R f Indicates the destruction ratio.

[0089]

[0090] Where (σ1-σ3) ult is the limit deviation stress, (σ1-σ3) f is the peak value of the deviatoric stress;

[0091]

[0092] Where G, F, and D are material constants.

[0093] The sample taken in step S1 is subjected to a dynamic triaxial test. The test conditions such as different stress ratios, compaction degrees, and water contents are set to obtain the strength parameter 2 of the embankment soil under vehicle load, i.e., the damping ratio λ d .

[0094] By processing the test data, the dynamic stress-strain relationship curves and the dynamic elastic modulus-confining pressure relationship curves were drawn. The dynamic stress-strain relationship and the dynamic elastic modulus-confining pressure variation law of the filling section and the excavation section soil under different compaction degrees, water contents and stress ratios were obtained respectively. An empirical model of the dynamic elastic modulus of soil was proposed. According to the relationship between dynamic stress and dynamic strain in the dynamic triaxial test, the permanent strain model of the roadbed was established.

[0095] The stress ratio is set with the initial stress ratio of 1:1 and gradually increased by 0.1 to 0.3 times, specifically 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2; the compaction degree of the filling section is set to 90%, 93%, 96%, and the consolidation degree of the excavation section is set to U t The settings are 70%, 80%, 90%, and 100%, the soil saturation is 20%, 40%, 60%, 80%, and 95%, and the number of dynamic load actions is 10,000 times.

[0096] Damping ratio λ dIt is obtained by the hysteresis curve method and calculated according to formula (5);

[0097]

[0098] Where ΔF is the area of ​​the hysteresis curve, and F is the area of ​​the triangle formed by the point on the hysteresis curve where the horizontal axis reaches the maximum value, the intersection of the perpendicular line from this point and the horizontal axis, and the origin.

[0099] S31, establish a two-dimensional model of the fill-cut junction section of the roadbed during the operation period through numerical simulation software such as ABAQUS or ANSYS, including the fill section and the cut section, such as Figure 2 As shown, the X-axis represents the longitudinal length of the roadbed, and the Y-axis represents the height of the roadbed; the other two-dimensional models along the transverse direction of the roadbed adopt the same method; the two-dimensional model is meshed, and the mesh shape is a rectangle. Taking a vertical section as an example, the height of the upper and lower adjacent nodes is h i , number the nodes from top to bottom, the first point of the vertical section is numbered J (0，j) , the following node codes are J (1，j) , J (2，j) …J (q，j) , q represents the number of rows of the node, and j represents the number of columns of the node (q, j = 0, 1, 2...).

[0100] The deformation modulus E of the soil under static load in the filling section obtained in step S2 is t and the tangent Poisson's ratio ν t , and the deformation modulus E of the soil under static load in the excavation section t and the tangent Poisson's ratio ν t As the calculation parameters of the two-dimensional model 1, the coordinates of each node in the two-dimensional model 1 and the vertical stress σ corresponding to each node are derived 1i , lateral stress σ 3i , i refers to the node number, i = 0, 1, 2,…

[0101] S32, a two-dimensional model 2 of the roadbed at the intersection of fill and cut section is established through numerical simulation software, and the grid division method is consistent with the division method of the two-dimensional model 1.

[0102] The deformation modulus E of the soil under static load in the filling section obtained in step S2 is t and the damping ratio λ d , and the deformation modulus E of the soil under static load in the excavation section t and the damping ratio λ dAs the calculation parameters of the two-dimensional model 2, dynamic analysis is used to apply a semi-sine wave load on the top surface of the roadbed, with a loading frequency of 2 times / s, a dynamic stress action time of 0.2s, and a dynamic stress interval time of 0.3s. The roadbed model is calculated to derive the dynamic stress σ′ corresponding to each node in the two-dimensional model 2. di , i refers to the node number, i = 0, 1, 2, .... The dynamic load application of the two-dimensional model established by the finite element software is achieved by editing the subroutine, importing it into the finite element software, and loading the program in the corresponding numerical simulation load step to realize the application of dynamic load.

[0103] S33, establish soil dynamic elastic modulus model and roadbed permanent strain model;

[0104] By processing the test data, the dynamic stress and dynamic strain relationship curves and the dynamic elastic modulus and confining pressure relationship curves are drawn. The dynamic stress and strain relationship and the dynamic elastic modulus and confining pressure variation law of the filling section and the excavation section soil under different compaction degrees, water content and other conditions are obtained, and the dynamic elastic modulus model of the soil in the filling section is proposed, as shown in formula (6-1):

[0105]

[0106] Specifically, k1, k2, k3, k4, b1 are test parameters, P a is the standard atmospheric pressure, E0 is the initial dynamic elastic modulus of the filling section, E 2d represents the dynamic elastic modulus of the soil in the fill section, e is a constant, σ 11 represents the major principal stress of the soil in the fill section, σ 31 represents the minor principal stress of the soil in the fill section, σ 11 / σ 31 It represents the stress ratio of the soil in the filling section, ω1 represents the water content of the soil in the filling section, and K represents the compaction degree of the soil in the filling section.

[0107] A multivariate linear regression analysis was performed on the test data. Based on the relationship between dynamic stress and dynamic strain in the dynamic triaxial test, a permanent strain model of the roadbed under dynamic load in the fill section was established, as shown in formula (7-1):

[0108]

[0109] Specifically, k5, k6, k7, k8, k9, k 10 , b2, b3 are test parameters, ε p is the initial plastic strain of the fill section, e is a constant, ε 1di It represents the permanent strain of the roadbed under the dynamic load of the fill section, and K represents the compaction degree of the soil in the fill section.

[0110] The methods for establishing the dynamic elastic modulus model and permanent strain model of the excavation section are the same as those for the filling section. The formulas for the dynamic elastic modulus model and permanent strain model of the excavation section are as follows (6-2) and (7-2), respectively:

[0111] Dynamic elastic modulus model of excavation section:

[0112]

[0113] k'1, k'2, k'3, k'4, b'1 are test parameters, P a is the standard atmospheric pressure, E'0 is the initial dynamic elastic modulus of the excavation section, and E' 2d represents the dynamic elastic modulus of the excavation section, U t represents the consolidation degree of the soil in the excavation section, σ 12 represents the major principal stress of the soil in the excavation section, σ 32 represents the minor principal stress of the soil in the excavation section, σ 12 / σ 32 It represents the stress ratio of the soil in the excavation section, and ω2 represents the water content of the soil in the excavation section.

[0114] Permanent strain model for excavation section:

[0115]

[0116] Where k'5, k'6, k'7, k'8, k'9, k' 10 , b'2, b'3 are test parameters, ε' p is the initial plastic strain of the excavation section, ε′ 1di It represents the permanent strain of the roadbed under the dynamic load of the excavation section.

[0117] Fully consider the state of the roadbed soil, such as: the model sets multiple factors such as stress ratio, confining pressure, consolidation ratio, and moisture content, to overcome the problem that the existing technology only considers a single factor or two of the factors, fails to fully consider the state of the soil, and thus extracts an inaccurate model.

[0118] S4, the vertical stress σ of each node in the fill section 1i , lateral stress σ 3i Substituting into formula (7-1), σ 1i Corresponding to σ in equation (7-1) 11 , σ 3i Corresponding to σ in equation (7-1) 31 ; Calculate the strain ε of each node under dynamic load 1diThen, the strain values ​​of the two adjacent upper and lower nodes of the vertical section are averaged to obtain the average strain value between the two adjacent upper and lower nodes. The average strain value between the two adjacent upper and lower nodes is added and divided by the total number of node segments n of the vertical section (that is, the number of all node segments divided by the vertical section), and the value is obtained. It represents the average strain value of the vertical section of the roadbed under dynamic load.

[0119] The settlement value S between the two adjacent upper and lower nodes on the vertical section under dynamic load is calculated by formula (8): 1f :

[0120]

[0121] Among them, h f represents the length between the upper and lower nodes of the fth node segment, f = 1, 2, ... n; then the settlement value S of a certain vertical section of the fill section of the fill-cut junction section under the action of dynamic load is calculated by formula (9): 1x , x represents a point on the longitudinal length X of the roadbed, that is, the position of the vertical section on the X-axis;

[0122]

[0123] The vertical stress σ of each node in the excavation section 1i , lateral stress σ 3i Substituting into formula (7-2), σ 1i Corresponding to σ in equation (7-2) 12 , σ 3i Corresponding to σ in equation (7-2) 32 ; The rest of the steps are the same, and the settlement value S′ of a certain vertical section of the excavation section of the fill-excavation junction under the action of dynamic load is calculated 1x .

[0124] S5, the vertical stress σ corresponding to each node of the fill section 1i , lateral stress σ 3i Substituting into formula (6-1), σ 1i Corresponding to σ in equation (6-1) 11 , σ 3i Corresponding to σ in equation (6-1) 31 ; Get the dynamic elastic modulus E of each node di , the stress σ of each node under the simultaneous action of dynamic load and static load is calculated by formula (10): di :

[0125] σ di =σ 1i +σ′ di (10)

[0126] Among them, σ′di Represents the dynamic stress at each node derived from the two-dimensional model.

[0127] The stress σ at each node di Substitute into formula (11) to calculate the strain value ε of each node under the simultaneous action of dynamic load and static load 2di :

[0128] ε 2di =σ di / E di (11)

[0129] According to the strain values ​​ε of the adjacent upper and lower nodes of the vertical section 2di Calculate the average value to obtain the average strain between the two adjacent upper and lower nodes. Add the average strain between the two adjacent upper and lower nodes and divide it by the total number of segments n (that is, the number of all node segments divided by the vertical section) to obtain It represents the average strain value of the vertical section of the roadbed under the simultaneous action of dynamic load and static load.

[0130] The settlement value S between the two adjacent upper and lower nodes on the vertical section under the simultaneous action of static load and dynamic load is calculated by formula (12): 2f :

[0131]

[0132] In the formula, h f represents the length between the upper and lower nodes of the fth node segment, f = 1, 2, ... n; then the settlement value S of a certain vertical section of the fill section of the fill-cut junction roadbed under the simultaneous action of static load and dynamic load is calculated by formula (13): 2x :

[0133]

[0134] The vertical stress σ of each node in the excavation section 1i , lateral stress σ 3i Substituting into formula (6-2), σ 1i Corresponding to σ in equation (6-2) 12 , σ 3i Corresponding to σ in equation (6-2) 32 ; The rest of the steps are the same, and the settlement value S′ of a certain vertical section of the excavation section of the fill-excavation junction section under the simultaneous action of static load and dynamic load is calculated 2x .

[0135] In steps S4 and S5, the strain of each section is obtained by averaging the strains of the upper and lower nodes, and then multiplied by the height of each section to obtain the deformation value of each section. Then, the settlement value of the section is obtained by cumulative summation. By analogy, the settlement deformation value of any cross-sectional position of the road surface can be calculated, which can fully consider the actual stress state of the roadbed soil, accurately and reliably; and overcomes the problem that the existing technology calculates the roadbed settlement through the prediction model and the actual value has a large error discrepancy.

[0136] S6, based on the superposition of unit node settlement, the total settlement deformation S of the fill section and the excavation section of the fill-excavation junction section at a certain vertical section is calculated according to formula (14): x , S′ x , that is, the total settlement deformation of any vertical section in the longitudinal length direction of the roadbed is obtained;

[0137] S x =S 1x +S 2x , S′ x =S′ 1x +S′ 2x (14).

[0138] Embodiment 3,

[0139] Evaluation of roadbed condition by total settlement:

[0140] The maximum settlement deformation of the excavation section and the filling section of the subgrade at the intersection of excavation and filling during the operation period is compared, and the larger one is compared with the standard deformation design value. If the maximum settlement deformation value is greater than the standard deformation design value, the subgrade does not meet the standard requirements and preventive measures need to be taken; if the maximum settlement deformation value is less than the standard deformation design value, the subgrade meets the standard requirements and is in good condition. The standard is the "Highway Subgrade Design Code" (JTG D30-2015), the highway grade is heavy, and the subgrade deformation design value is 20mm.

[0141] Evaluate the roadbed condition from the perspective of material tensile strength:

[0142] The maximum node strain value ε of the top surface of the roadbed under the simultaneous action of dynamic load and static load calculated in step S5 2dimax (i.e. the peak strain value of the top surface after construction) is compared with the standard strain value of cement concrete water-stable base in the specification. If ε 2dimax If the strain of cement concrete water-stable base is greater than the design value, the pavement water-stable base will crack and preventive measures need to be taken; 2dimaxIf the strain is less than the design value of the standard strain, the pavement water-stable base will not crack and will be in good condition. The standard is "Technical Specifications for Highway Cement Concrete Pavement Construction" (JTG / T F30-2014). The standard strain value is obtained by the formula ε=σ / E. The highway grade is heavy, and its tensile strength is 2.0MPa. The strength grade of lean concrete is C30, and its elastic modulus E=3.35×10 4 MPa.

[0143] Both evaluation results should meet the requirements at the same time.

[0144] The creep deformation process is very long and the deformation is very small, but the deformation of the roadbed cannot be ignored; the most common method for monitoring roadbed creep deformation is deformation monitoring, so as to timely discover safety hazards, but long-term deformation monitoring observation is easily interfered by the outside world and costs a lot of money. At the same time, the actual measured data of the project is often limited to a few points, which cannot fully reflect the changes in soil properties and the interaction characteristics between soil and structures, and cannot predict the deformation of the roadbed in advance. The self-weight stress level of general model tests is very low, and the influence of capillary phenomena is prominent. The model test results cannot realistically reflect the characteristics of the actual engineering situation, especially for soft clay roadbeds. The study of soil creep deformation characteristics mainly uses indoor physical and mechanical properties tests and creep constitutive models. Indoor tests cannot fully simulate the creep process of soil under actual conditions, and cannot accurately extract creep constitutive models, resulting in large errors.

[0145] Embodiment 4,

[0146] Static triaxial test test conditions: the confining pressure is set to 10kPa, 20kPa, 30kPa, 40kPa, 50kPa, the compaction degree of the fill section is set to 90%, 93%, 96%, and the consolidation degree of the excavation section is set to U t (Take clay as an example) Set it to 70%, 80%, 90%, 100%, the excavation section uses the natural moisture content of 31.2%, and the filling section uses the optimal moisture content of 23.5%;

[0147] Test conditions of dynamic triaxial test: stress ratio with initial stress ratio of 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8 and 1:2; compaction degree of soil in fill section is set to 90%, 93% and 96%, consolidation degree of soil in excavation section is set to 70%, 80%, 90% and 100%, natural moisture content of soil in excavation section is 31.2%, and optimum moisture content of soil in fill section is 23.5%; number of dynamic load actions is 10,000 times.

[0148] According to the above test conditions, dynamic and static triaxial tests are performed respectively to obtain relevant parameters, as shown in steps S1 and S2.

[0149] Two-dimensional models one and two are established respectively by numerical simulation software, and relevant calculation parameters are assigned respectively, as shown in steps S31 and S32 for details.

[0150] The test data were processed and the soil dynamic elastic modulus models of the excavation section and the filling section and the permanent strain model of the roadbed were established respectively.

[0151] Dynamic elastic modulus model of fill section:

[0152] Unit: MPa

[0153] Permanent strain model of roadbed fill section:

[0154]

[0155] Dynamic elastic modulus model of excavation section:

[0156] Unit: MPa

[0157] Permanent strain model of roadbed excavation section:

[0158]

[0159] Take a vertical section in the fill section model as an example (q = 6), and derive the vertical stress σ of the vertical section 1i , lateral stress σ 3i , then the vertical stress σ 1i , lateral stress σ 3i Substituting into the permanent strain model of the roadbed fill section, the calculation results are shown in Table 1, and the steps are detailed in S4. The settlement calculation method of any vertical section of the roadbed fill section is consistent with the settlement calculation method of the vertical section.

[0160] Table 1 Roadbed fill section S 1x Calculate the correlation data (K = 0.96)

[0161]

[0162] The vertical stress σ 1i , lateral stress σ 3i Substituting into the dynamic elastic modulus model of the roadbed fill section, the calculation results are shown in Table 2, and the steps are detailed in S5.

[0163] Table 2 Roadbed filling section S 2x Calculate the correlation data (K = 0.96)

[0164]

[0165] Based on the above data, the total settlement deformation value S of the roadbed fill section is calculated by formula 14. x =26.98mm.

[0166] Two-dimensional models 1 and 2 are established respectively by numerical simulation software, and relevant calculation parameters are assigned respectively, as shown in steps S31 and S32. A vertical section in the excavation section model is taken as an example (q=5), and the vertical stress σ of the vertical section is derived. 1i , lateral stress σ 3i , then the vertical stress σ 1i , lateral stress σ 3i Substituting into the permanent strain model of the roadbed excavation section, the calculation results are shown in Table 3, and the steps are detailed in S4. The settlement calculation method of any vertical section of the roadbed excavation section is consistent with the settlement calculation method of the vertical section.

[0167] Table 3 Roadbed excavation section S 1x Calculate relevant data (U t =0.90)

[0168]

[0169]

[0170] The vertical stress σ 1i , lateral stress σ 3i Substituting into the dynamic elastic modulus model of the roadbed excavation section, the calculation results are shown in Table 4, and the steps are detailed in S5.

[0171] Table 4 Roadbed filling section S 2x Calculate relevant data (U t =0.90)

[0172]

[0173] In the table, "6.2796E-06" means 6.2796×10 -6 .

[0174] Based on the above data, the total settlement deformation value S′ of the roadbed excavation section is calculated by formula 14 x =1.23mm. The maximum total settlement of the roadbed occurs in the filling section, and its value is S x =26.98mm>h=20mm, which does not meet the total settlement index of the specification. According to the data in Tables 2 and 4, the maximum strain value of the top node ε 2dmax =6.0284×10 -4 , the highway grade is heavy, its tensile strength is 2.0MPa, the lean concrete strength grade is C30, its elastic modulus E=3.35×10 4 MPa, calculate its strain value ε d =0.597×10 -4 , because ε 2dmax =6.0284×10 -4>ε d =0.597×10 -4 , the pavement's water-stable base will crack and preventive measures need to be taken.

[0175] Taking the two points of roadbed excavation section J(0,5) and filling section J(0,6) as examples, the total settlement values ​​of the two points were measured by an electronic level through engineering examples, recorded as the total settlement measured value. The measurement time was in March, June, September and December. The total settlement values ​​of the two points were calculated using the above technical method, recorded as the total settlement calculated value. The relative error and average relative error between the two were calculated, as shown in Table 5 below;

[0176] Table 5 Error analysis between calculated and measured values ​​of roadbed settlement

[0177]

[0178] It can be concluded from Table 5 that the average relative errors between them are all within 10%, which is within the allowable range, verifying the accuracy of the estimated settlement deformation of the roadbed at the intersection of fill and cut during the operation period of the present invention.

[0179] The embodiment of the present invention is composed of a test system, a numerical simulation system, and a differential settlement evaluation system, which integrates dynamic and static triaxial tests and numerical simulations, and calculates the settlement deformation of the roadbed at the intersection of fill and excavation during the operation period under the action of vehicle loads, and can fully consider various states such as consolidation of the roadbed soil during the operation period and various adverse external factors. The embodiment of the present invention combines the results of dynamic and static triaxial tests with finite element analysis. The settlement of the embankment model under static load is obtained by numerical calculation by using the relevant parameters of the static triaxial test to establish a model. The settlement of the embankment model under dynamic load is obtained by numerical calculation by using the relevant parameters of the static triaxial test and the relevant parameters of the dynamic triaxial test to establish a model. Both settlement calculations involve the superposition of unit node settlements. The settlement calculation is performed on each node of the roadbed model, and the influence of the settlement generated by each node on the total settlement is fully considered. The settlement value obtained is more accurate and has higher reliability.

[0180] The present invention sets the soil weight parameter during the modeling process, thereby reflecting the roadbed deformation (elastic deformation) under the static load; the dynamic stress σ′ corresponding to each node obtained in step S32 di It reflects the deformation of the roadbed under the action of dynamic load (dynamic deformation); the permanent strain model of the roadbed under the action of dynamic load established in step S33 reflects the permanent deformation (creep deformation) caused by slow changes; the embodiment of the present invention organically combines elastic deformation, dynamic deformation and creep deformation, comprehensively and accurately considers the deformation caused by the roadbed soil, greatly improves the estimation accuracy of the settlement deformation of the roadbed in the fill-excavation junction section, and effectively prevents road cracking.

[0181] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for estimating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load, characterized in that: Follow these steps: S1, sampling at the excavation section and filling section at the junction of the embankment and fill; S2, static triaxial test and dynamic triaxial test are performed on the samples in step S1, and the test conditions of different confining pressure, compaction degree and water content are set in the test. The deformation modulus E of the embankment soil under static load is obtained through static triaxial test. t and the tangent Poisson's ratio ν t ; The damping ratio λ of the embankment soil under vehicle load is obtained through dynamic triaxial test d ; S3, using numerical simulation software to establish a two-dimensional model of the roadbed at the intersection of the fill and cut section during the operation period, including the cut section and the fill section; meshing the two-dimensional model, and numbering the nodes in any vertical section from top to bottom, where i represents the node number; the deformation modulus E obtained in step S2 is t and the tangent Poisson's ratio ν t As input parameters, the vertical stress σ corresponding to each node is obtained 1i , lateral stress σ 3i ; The deformation modulus E obtained in step S2 t , damping ratio λ d As the input parameter, the dynamic stress σ corresponding to each node is obtained d ' i ; S4, the vertical stress σ of each node in the excavation section and the filling section 1i , lateral stress σ 3i Substitute them into the corresponding permanent strain model under the action of dynamic load, obtain the strain of each node under the action of dynamic load, and obtain the settlement value of a certain vertical section of the fill section and the excavation section of the fill-excavation junction section under the action of dynamic load according to the corresponding strain; S5, the vertical stress σ of each node in the excavation section and the filling section 1i , lateral stress σ 3i Substitute into the corresponding dynamic elastic modulus model to obtain the dynamic elastic modulus E of each node di , combined with the dynamic stress corresponding to each node, the strain value of each node under the simultaneous action of dynamic load and static load is obtained, and then according to the corresponding strain value, the settlement value of a certain vertical section of the fill section and the cut section of the fill-cut junction roadbed under the simultaneous action of static load and dynamic load is obtained respectively; S6, based on the superposition of unit node settlement, the two settlement values ​​of the same vertical section are added together to obtain the total settlement deformation of any vertical section in the longitudinal length direction of the roadbed; In step S4, the permanent strain model of the roadbed under the dynamic load of the filling section is shown in formula (7-1), and the permanent strain model of the roadbed under the dynamic load of the excavation section is shown in formula (7-2); Among them, k5, k6, k7, k8, k9, k 10 , b2, b3 are test parameters, ε p is the initial plastic strain of the fill section, e is a constant, P a is the standard atmospheric pressure; ε 1di Indicates the permanent strain of the roadbed under the dynamic load of the fill section; k'5, k'6, k'7, k'8, k'9, k' 10 , b'2, b'3 are test parameters, ε' p is the initial plastic strain of the excavation section, ε 1di represents the permanent strain of the roadbed under the dynamic load of the excavation section; σ 11 represents the major principal stress of the soil in the fill section, σ 31 represents the minor principal stress of the fill section soil, σ 11 / σ 31 represents the stress ratio of the fill section soil, ω1 represents the water content of the fill section soil, K represents the compaction degree of the fill section soil; σ 12 represents the major principal stress of the soil in the excavation section, σ 32 represents the minor principal stress of the soil in the excavation section, σ 12 / σ 32 represents the stress ratio of the soil in the excavation section, and ω2 represents the moisture content of the soil in the excavation section; The vertical stress σ of each node in the fill section 1i , lateral stress σ 3i Substitute into formula (7-1) to calculate the strain ε of each node under dynamic load 1di , calculate the average strain value of the adjacent upper and lower nodes of the vertical section, and obtain the average strain value between the adjacent upper and lower nodes. Add the average strain value between the adjacent upper and lower nodes and divide it by the total number of node segments n of the vertical section to obtain It represents the average strain value of the vertical section of the roadbed under dynamic load; The settlement value S between the two adjacent upper and lower nodes on the vertical section under dynamic load is calculated by formula (8): 1f : Among them, h f represents the length between the upper and lower nodes of the fth node segment, f = 1, 2, ... n; then the settlement value S of a certain vertical section of the fill section roadbed at the fill-cut junction under the action of dynamic load is calculated by formula (9): 1x , x represents a point on the longitudinal length X of the roadbed, that is, the position of the vertical section on the X-axis; The vertical stress σ of each node in the excavation section 1i , lateral stress σ 3i Substitute it into formula (7-2) and follow the other steps to find the settlement value S′ of a vertical section of the excavation section of the fill-excavation junction under the action of dynamic load. 1x ; In step S5, the dynamic elastic modulus model of the soil in the filling section is shown in formula (6-1), and the dynamic elastic modulus model of the soil in the excavation section is shown in formula (6-2); Among them, k1, k2, k3, k4, b1 are test parameters, P a is the standard atmospheric pressure, E0 is the initial dynamic elastic modulus of the filling section, E 2d represents the dynamic elastic modulus of the soil in the filling section, e is a constant; k'1, k'2, k'3, k'4, b'1 are test parameters, E'0 is the initial dynamic elastic modulus of the excavation section, E' 2d represents the dynamic elastic modulus of the excavation section, U t Indicates the degree of consolidation of the soil in the excavation section; The vertical stress σ corresponding to each node of the filling section obtained in step S3 is 1i , lateral stress σ 3i Substituting into formula (6-1), the dynamic elastic modulus E of each node is calculated. 2di ; The stress σ of each node under the simultaneous action of dynamic load and static load is calculated by formula (10): di : s di =s 1i +s′ di (10) The stress σ di Substituting into formula (11), we can obtain the strain value ε of each node under the simultaneous action of dynamic load and static load: 2di : e 2di =s di / E di (11) According to the strain values ​​ε of the adjacent upper and lower nodes of the vertical section 2di Calculate the average value to obtain the average strain between the two adjacent upper and lower nodes. Add the average strain between the two adjacent upper and lower nodes and divide it by the total number of segments n to obtain It represents the average strain value of the vertical section of the roadbed under the simultaneous action of dynamic load and static load; The settlement value S between the two adjacent upper and lower nodes on the vertical section under the simultaneous action of static load and dynamic load is calculated by formula (12): 2f : In the formula, h f represents the length between the upper and lower nodes of the fth node segment, f = 1, 2, ... n; then the settlement value S of a certain vertical section of the fill section roadbed at the fill-cut junction under the simultaneous action of static load and dynamic load is calculated by formula (13): 2x : The vertical stress σ of each node in the excavation section 1i , lateral stress σ 3i Substitute it into formula (6-2), and follow the same steps to find the settlement value S′ of a certain vertical section of the excavation section of the fill-excavation junction under the simultaneous action of static load and dynamic load. 2x .

2. According to the method of claim 1, the method is characterized by: The step S1 specifically comprises: taking on-site sampling at the excavation section at the junction of the embankment excavation and filling section; taking original soil from the embankment filling section and preparing samples by static pressure method; removing impurities from the excavation section samples and sealing them with plastic wrap to keep the samples in the original state of the soil; removing impurities from the filling section soil samples, air drying them, sieving them, and preparing samples by static pressure method, and the sample size is consistent with that of the excavation section samples.

3. According to the method for estimating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load in claim 1, it is characterized in that: In step S2, the static triaxial test is carried out by the drainage consolidation method, the confining pressure is set to 10 kPa to 50 kPa, the compaction degree of the filling section is set to 90% to 96%, and the consolidation degree of the excavation section is set to U t Set to 70%, 80%, 90%, 100%, the excavation section soil adopts natural moisture content, and the filling section soil adopts optimal moisture content.

4. According to the method for estimating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load in claim 1, it is characterized in that: In step S2, the deformation modulus E t , Tangent Poisson's ratio ν t The Duncan-Zhang hyperbolic model is used to fit the experimental data, as shown in formula (1): Where P a is the standard atmospheric pressure, K and n are experimental constants, c is the cohesion, and φ is the internal friction angle; is the center of the circle, The method and formula for drawing the drained consolidation Mohr stress circle and strength envelope on the τ-σ plane with radius τ f =σtanφ+c to calculate the parameters c and φ; τ f is the shear strength of soil, σ is the normal stress on the shear sliding surface; σ 1f represents the ultimate major principal stress, σ 3f represents the limiting minor principal stress, σ3 represents the minor principal stress, σ1 represents the major principal stress, R f represents the destruction ratio; Where (σ1-σ3) ult is the limit deviation stress, (σ1-σ3) f is the peak value of the deviatoric stress; Where G, F, and D are material constants.

5. According to the method for estimating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load in claim 1, it is characterized in that: In step S2, the damping ratio λ d It is obtained by the hysteresis curve method and calculated according to formula (5); Where ΔF is the area of ​​the hysteresis curve, and F is the area of ​​the triangle formed by the point on the hysteresis curve where the horizontal coordinate reaches the maximum value, the intersection of the vertical line of this point with the horizontal axis, and the origin.

6. A method for evaluating roadbed settlement, characterized in that: Based on the method for estimating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load as claimed in claim 1, specifically: The maximum settlement deformations of the excavation section and the filling section of the roadbed at the junction of excavation and fill during the operation period are compared, and the larger one is compared with the standard deformation design value. If the maximum settlement deformation value is greater than the standard deformation design value, the roadbed does not meet the standard requirements; if the maximum settlement deformation value is less than the standard deformation design value, the roadbed meets the standard requirements.

7. A method for evaluating roadbed settlement, characterized in that: Based on the method for estimating the settlement deformation of the roadbed at the intersection of fill and cut during operation under vehicle load as claimed in claim 1, specifically: The maximum node strain value ε of the top surface of the roadbed under the simultaneous action of dynamic load and static load calculated in step S5 2dimax Compared with the standard strain value of cement concrete water-stable base in the specification, if ε 2dimax If ε is greater than the design strain value, it does not meet the specification requirements; 2dimax If it is less than the design strain value, it meets the specification requirements.

8. A system for estimating the settlement and deformation of the roadbed at the intersection of fill and cut during operation under vehicle load, characterized in that: Based on the method for estimating the settlement deformation of the fill-excavation junction section of the operation period under the vehicle load described in claim 1, the test system includes a static triaxial test and a dynamic triaxial test, which are used to provide relevant calculation parameters for the numerical simulation system: the deformation modulus E of the soil in the fill section and the excavation section under the static load t , Tangent Poisson's ratio ν t and the damping ratio λ d ; Numerical simulation system, used to establish a two-dimensional model of the intersection of fill and cut section of the roadbed during operation, calculate and derive the vertical stress σ corresponding to each node 1i , lateral stress σ 3i , dynamic stress σ′ di ; Differential settlement prediction system is used to estimate the vertical stress σ 1i , lateral stress σ 3i , permanent strain model under dynamic load, dynamic elastic modulus model, dynamic stress σ′ corresponding to each node di The total settlement deformation of any vertical section in the longitudinal length direction of the roadbed is obtained.

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