A method for designing a monolithic panel structure for a reinforced soil retaining wall

Abstract

The application discloses a kind of integral panel structure design method for reinforced earth retaining wall, comprising the following steps: S1. the earth pressure of integral panel is calculated, the earth pressure of integral panel is between the active earth pressure determined by double-wedge method and static earth pressure;S2. the earth pressure of integral panel and the load acting on the top of reinforced earth retaining wall are used as external force, the internal force of integral panel is calculated;Integral panel is regarded as continuous beam, and the reinforced material of integral panel is used as spring support point, the combined design response value of integral panel and reinforced material is calculated, and the stress of integral panel structure and the stress of reinforced material are calculated;S3. the drawing design of reinforced material is carried out;S4. the reinforcement of integral panel is calculated.The method fully considers the characteristics of the earth pressure of reinforced soil and the flexible creep characteristics of reinforced material, effectively solves the problem that the integral panel structure design of reinforced earth retaining wall is unreasonable, and easily causes panel damage and excessive deformation.

Description

Technical Field

[0001] This invention relates to the field of transportation subgrade infrastructure technology, and in particular to a design method for an integral panel structure for reinforced soil retaining walls. Background Technology

[0002] Reinforced soil retaining walls have been widely used in my country's railway, highway, water conservancy, construction, and coal mining sectors, primarily for geotechnical structures such as roadbeds, platforms, bridge abutments, dams, revetments, and waterway wharves. As a retaining structure, reinforced soil retaining walls offer advantages such as simple construction, small footprint, aesthetically pleasing appearance, and low cost. A reinforced soil retaining wall mainly consists of wall panels, reinforcing bars, and fill material. The friction between the fill material and the reinforcing bars transfers lateral earth pressure to the bars, stabilizing the soil mass. This composite structure also resists earth pressure at the rear of the reinforced soil mass, thus maintaining the stability of the entire structure.

[0003] Currently, most railways in my country use reinforced concrete panels. When the panels are directly connected to the tie rods, structural design is required due to the horizontal earth pressure from the wall and the resistance of the tie rods. Commonly used panels are classified according to the wall structure as: composite panels and monolithic panels. Hollow concrete modules, wire mesh spraying, and other lightweight wall materials can also be used. Among them, monolithic panels, due to their reinforced casing, are theoretically considered not to bear earth pressure. Therefore, C30 reinforced concrete is used with reinforcement arranged according to structural requirements to beautify the wall surface, protect the tie rods from mechanical damage, and prevent the tie rod material from aging due to sunlight.

[0004] In practical engineering, monolithic panels have strong resistance to deformation. However, due to the creep of the reinforcing materials, the panels are still subjected to significant soil pressure. Therefore, it is not reasonable to design monolithic panels according to structural requirements, as this can easily lead to panel damage and excessive deformation. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of unreasonable design of existing integral panel structures, which easily lead to panel damage and excessive deformation, and to provide an integral panel structure design method for reinforced soil retaining walls.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A method for designing an integral panel structure for reinforced soil retaining walls includes the following steps:

[0008] S1. Calculate the earth pressure on the monolithic panel, wherein the earth pressure on the monolithic panel is between the active earth pressure determined by the double wedge method and the at-rest earth pressure.

[0009] S2. Using the earth pressure on the monolithic panel and the load acting on the top of the reinforced soil retaining wall as external forces, calculate the internal forces of the monolithic panel; treating the monolithic panel as a continuous beam and the reinforcing material of the monolithic panel as a spring fulcrum, calculate the combined design response value of the action of the monolithic panel and the reinforcing material, and calculate the structural forces of the monolithic panel and the forces of the reinforcing material.

[0010] S3. Perform the pull-out design of the reinforcing material;

[0011] S4. Calculate the reinforcement of the monolithic panel.

[0012] The present invention provides a design method for an integral panel structure of reinforced soil retaining walls. This method establishes a complete and effective design method for an integral panel structure of reinforced soil retaining walls, which fully considers the soil pressure characteristics of reinforced soil and the flexible creep characteristics of reinforcing materials. The method generalizes the integral reinforced concrete panel as an elastically supported continuous beam with one end simply supported and the other end free, and assumes that the reinforcing materials are a series of extensible and deformable spring supports, which facilitates the subsequent calculation of the loads on the integral panel and the reinforcing materials. The method effectively solves the problem that unreasonable design of integral panel structures of reinforced soil retaining walls can easily lead to panel damage and excessive deformation.

[0013] Optionally, the at-rest earth pressure coefficient determined by the double-wedge method in S1 is calculated using Formula 1, which is:

[0014]

[0015] In the formula:

[0016] K0—the coefficient of earth pressure at rest determined by the double-wedge method;

[0017] K h —Horizontal seismic coefficient;

[0018] —The internal friction angle of the back of a reinforced soil retaining wall, in °.

[0019] Optionally, the active earth pressure determined by the double-wedge method in S1 is calculated as follows:

[0020] Assuming all forces are in a state of limit equilibrium, the region of the reinforced soil retaining wall near the fill is defined as zone B, and the region of the reinforced soil retaining wall near the monolithic panel is defined as zone F. The reaction force in zone B is calculated as follows:

[0021] Formula 2:

[0022] Formula 3:

[0023] The reaction force in region F is calculated as follows:

[0024] Formula 4:

[0025] Formula 5:

[0026] Formulas 2 through 5:

[0027] W B —Weight of wedge B, in kN / m;

[0028] W F —Weight of wedge F, in kN / m;

[0029] L B —Load acting on wedge B, unit: kN / m;

[0030] L F —Load acting on the wedge F, unit: kN / m;

[0031] P F —Resultant earth pressure, unit: kN / m;

[0032] P BF —Resultant earth pressure of wedge B, unit: kN / m;

[0033] R F —The reaction force at the bottom of the wedge F, in kN / m;

[0034] R B —The reaction force at the bottom of wedge B, in kN / m;

[0035] —Inner friction angle of reinforced soil retaining wall, unit: °;

[0036] —Internal friction angle between wedges, unit: °;

[0037] —Internal friction angle of wedge B packing, unit: °;

[0038] —Internal friction angle of wedge F packing, unit: °;

[0039] θ B —Angle between the fracture surface of wedge B and the horizontal line, unit: °;

[0040] θ BF —Angle between wedge B and the vertical line, unit: °;

[0041] θ F —Angle between the fracture surface of wedge F and the horizontal line, unit: °;

[0042] θ FW —Angle between the back of the reinforced soil retaining wall and the vertical line, unit: °;

[0043] The equivalent uniformly distributed stress of the reinforced soil retaining wall is calculated using Formula Six, which is:

[0044]

[0045] In the formula:

[0046] P Fx —Horizontal earth pressure exerted on the monolithic panel by the double wedges, unit: kN;

[0047] H—Height of reinforced soil retaining wall, in meters;

[0048] M—Bending moment of reinforced soil retaining wall, unit: kN.m;

[0049] q1—Uniformly distributed stress at the top of the reinforced soil retaining wall, unit: kPa;

[0050] q2—Uniformly distributed stress at the bottom of the reinforced soil retaining wall, unit: kPa.

[0051] Optionally, in S2, the spring coefficient of the reinforcing material is calculated using Formula 7, which is:

[0052] K s =a s ×T s / (0.05×L)

[0053] In the formula:

[0054] K s —The spring coefficient of the reinforcing material;

[0055] T s —Tensile strength of air-reinforced material when stretched by 5% strain;

[0056] L—Standard length of the reinforcing material, in meters;

[0057] a s — Correction factor for reinforced materials considering constraints.

[0058] Optionally, in S2, the method for calculating the structural stress of the integral panel and the stress of the reinforcing material is as follows:

[0059] Based on the elastically supported continuous beam, establish 2n+1 equations to form Formula 8. Calculate the 2n+1 bending moments and deformation values ​​at the junction of the reinforced material and the integral panel. Formula 8 is:

[0060]

[0061] In the formula,

[0062] M i — Bending moment at the junction of the reinforcing material at point i and the monolithic panel, unit: kN / m;

[0063] v i —Deformation of the reinforcing material at point i, unit: kN / m;

[0064] EI—Integral panel stiffness, unit: kN / m 2 ;

[0065] q i —The earth pressure load stress at the i-th point reinforced material, in kPa;

[0066] K s —The spring coefficient of the reinforcing material.

[0067] Optionally, S3 includes the following steps:

[0068] The ultimate limit state calculation of the crack bearing capacity of the reinforced material is performed according to Formula 9, which is:

[0069] γ0S d ≤R d

[0070] In the formula:

[0071] γ0 — Structural importance coefficient;

[0072] S d —Combined action design response value;

[0073] R d —Design value of structural resistance;

[0074] The expressions for the combined design response value of the reinforcing material and the design value of the structural resistance of the reinforcing material are as follows:

[0075] Formula 10: S di =K si ·v i

[0076] Formula 11: R di =T i =min(T) P ,T k )

[0077] In Formulas 10 and 11:

[0078] R di —Design value of structural resistance of the reinforcing material at point i;

[0079] S di—Design response value of the reinforcement material at point i;

[0080] K si —The spring coefficient of the reinforcing material at point i;

[0081] T i —Design tensile force of the reinforcing material, unit: kN / m;

[0082] T p —Tensile strength of the reinforcing material, unit: kN / m;

[0083] T k — Pull-out resistance of the reinforcing material, unit: kN / m;

[0084] The reinforcing material is designed for normal use based on formulas 12 and 13:

[0085] Formula 12: S d ≤C

[0086] Formula Thirteen: S d =v i

[0087] In the formula:

[0088] C—the limit specified for deformation.

[0089] Optionally, calculating the reinforcement of the monolithic panel in S4 involves designing the bending, shear, and crack resistance of the reinforced concrete members on each section of the monolithic panel, including the following steps:

[0090] S41. Perform bending resistance calculation. The reinforced concrete member shall be checked for crack bearing capacity ultimate limit state according to Formula 9.

[0091] S42. Perform shear resistance check. The reinforced concrete member shall be checked for ultimate shear capacity according to Formula 9.

[0092] S43. Crack calculation is performed, and the serviceability limit state design of the reinforced concrete member adopts Formula Twelve.

[0093] Optionally, S in S41 d The calculation formula is:

[0094] For normal water levels in general areas and flooded areas, Formula Fourteen is used:

[0095] S d =γ G S Gk +γ Q S Qk

[0096] In the formula:

[0097] S Gk —Bending moment or shear force generated by earth pressure;

[0098] S Qk — Bending moment or shear force generated by dynamic load;

[0099] γ G —Earth pressure effect coefficient using limit state design;

[0100] γ Q —Load action factor using limit state design;

[0101] When the flood level is under immersion conditions, Formula 15 is used:

[0102] S d =γ G S Gk +S wk +γ Q S Qk

[0103] In the formula:

[0104] S wk —Bending moment or shear force generated by water pressure;

[0105] In earthquake conditions, Formula Sixteen is used:

[0106] S d =γ G S Gk +γ I S Ek +γ Q S Qk

[0107] In the formula:

[0108] S Ek —The bending moment or shear force generated by the earthquake force;

[0109] γ I —Seismic action coefficients based on limit state design;

[0110] S41 R d The calculation formula is Formula Seventeen:

[0111]

[0112] The height x of the concrete compression zone is determined according to Formula 18. Formula 18:

[0113] α1f c bx = f y A s -f′ y A′ s

[0114] The height x of the concrete compression zone meets the conditions of Formulas 19 and 20:

[0115] Formula 19: x≤ξ b h0

[0116] Formula 20: x≥2a′ s

[0117] Formulas 17 to 20:

[0118] a1 — coefficient, taken as 1.0;

[0119] f c —Design value of axial compressive strength of concrete;

[0120] f y —Design strength value for ordinary steel reinforcement;

[0121] A s —Cross-sectional area of ​​longitudinal ordinary reinforcing bars in the tension zone, unit: N / mm² 2 ;

[0122] A s — Cross-sectional area of ​​longitudinal ordinary reinforcing bars in the compression zone, unit: N / mm² 2 ;

[0123] b—Unit width of the integral panel, unit: mm;

[0124] h0—Effective height of the integral panel section, unit: mm;

[0125] a′ s —The distance from the resultant point of the longitudinal reinforcing bars in the compression zone to the compression edge of the section, in mm;

[0126] ξ b —Relative limit pressure zone height, unit: mm.

[0127] Optionally, in S42, the combined action design response value is calculated according to Formula XIV and Formula XV;

[0128] S42 in R d The calculation formula is:

[0129] Formula 21: R d =0.025β c f c bh0

[0130] In the formula:

[0131] β c —Concrete strength influence coefficient, taken as 1.0;

[0132] When stirrups or bent-up bars are used, the formula for calculating the design value of the shear resistance of the inclined section of a reinforced concrete flexural member is as follows:

[0133] Formula 22: R d =V cs +V bs

[0134] Formula 23:

[0135] Formula 24: V bs =0.8f yv A sb sinα s

[0136] Formulas 22 to 24:

[0137] V cs —Design values ​​of shear resistance of concrete and stirrups on the inclined section of the member;

[0138] V bs —Design value of tensile strength of bent-up reinforcement on the inclined section of the component;

[0139] α cv —Shear resistance coefficient of inclined concrete section;

[0140] A sv —The total cross-sectional area of ​​each leg of the stirrups configured in the same cross section;

[0141] S— Spacing of stirrups along the length of the member;

[0142] f yv —Design value of tensile strength of stirrups or bent-up bars;

[0143] A sb —The cross-sectional area of ​​bent-up reinforcing bars in the same plane;

[0144] α s —The angle between the bent-up reinforcement on the inclined section and the longitudinal axis of the member.

[0145] Optionally, in S43, the formula for calculating the maximum crack width is as follows:

[0146] Formula 25:

[0147] Formula 26:

[0148] Formula 27:

[0149] Formula 28:

[0150] Formula 29:

[0151] Formulas 25 to 29:

[0152] α cr —Component stress characteristic coefficient;

[0153] ψ—Coefficient of non-uniform strain of longitudinal tensile reinforcement between cracks;

[0154] σ sq —Longitudinal tensile reinforcement stress in reinforced concrete members calculated according to the quasi-permanent load combination, unit: n / mm 2 ;

[0155] E s —Elastic modulus of reinforcing steel, unit: n / mm 2 ;

[0156] c s —The distance from the outermost longitudinal tensile reinforcement to the bottom edge of the tension zone, in mm;

[0157] d eq —Equivalent diameter of longitudinal reinforcement in the tension zone, unit: mm;

[0158] ρ te —The longitudinal tensile reinforcement ratio calculated based on the effective tensile concrete cross-sectional area;

[0159] f tk This refers to the standard value of the axial tensile strength of concrete, in N / mm². 2 ;

[0160] A s —Cross-sectional area of ​​longitudinal ordinary reinforcing bars in the tension zone, unit: N / mm² 2 ;

[0161] h0—Effective height of the integral panel section, unit: mm;

[0162] A te —Effective tensile concrete cross-sectional area, unit: N / mm² 2 ;

[0163] d i —The nominal diameter of the i-th type of longitudinal tensile reinforcement in the tension zone, in mm;

[0164] n i —The number of the i-th type of longitudinal tensile reinforcement bars in the tension zone;

[0165] v i —The relative bond characteristic coefficient of the i-th type of longitudinal reinforcement in the tension zone;

[0166] In Formula 27, Mq When using standard combinations,

[0167] S d =S Gk +S Qk

[0168] In Formula 27, M q When using quasi-permanent combinations,

[0169] S d =S Gk +ψ q S Qk

[0170] In the formula:

[0171] ψ q —The quasi-permanent value coefficient of variable action, ψ q ≥0.6.

[0172] Compared with the prior art, the beneficial effects of the present invention are:

[0173] 1. The present invention provides a design method for an integral panel structure of reinforced soil retaining walls, establishing a complete and effective design method for integral panel structures of reinforced soil retaining walls. This method fully considers the soil pressure characteristics of the reinforced soil and the flexible creep characteristics of the reinforcing materials. The method generalizes the integral reinforced concrete panel as a continuous elastically supported beam with one end simply supported and the other end free, and assumes the reinforcing materials as a series of extensible and deformable spring supports, facilitating subsequent calculations of the loads on the integral panel and the reinforcing materials. This method effectively solves the problem of unreasonable integral panel structure design in reinforced soil retaining walls, which easily leads to panel damage and excessive deformation.

[0174] 2. The monolithic panel structure design method for reinforced soil retaining walls provided by this invention takes into full account the tensile, pull-out, and deformation characteristics of each layer of reinforcing material and the monolithic panel joint, considering the characteristics of geosynthetic materials. It sets the pull-out bearing capacity of each layer of geosynthetic material to be less than or equal to the minimum value of the tensile and pull-out forces of the reinforcing material. Based on the pull-out test of geosynthetic materials, the deformation limit is taken as the deformation value of the standard reinforcing material length stretched by 5% in air, and the limit state equation is established. Attached Figure Description

[0175] Figure 1 Schematic diagram of reinforced soil retaining wall;

[0176] Figure 2 Force analysis diagram of wedge B;

[0177] Figure 3 The force analysis diagram of wedge F is shown below;

[0178] Figure 4This is a stress calculation model diagram for the integral panel and reinforcing materials.

[0179] Attached diagram labels: 1-Integral panel, 2-Reinforcing material, 3-Area B, 4-Area F. Detailed Implementation

[0180] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0181] Example 1

[0182] like Figure 1-4 As shown, a design method for an integral panel structure for reinforced soil retaining walls includes the following steps:

[0183] S1. Calculate the earth pressure of the monolithic panel 1, which is between the active earth pressure and the at-rest earth pressure determined by the double wedge method.

[0184] Furthermore, the at-rest earth pressure coefficient determined by the double-wedge method in S1 is calculated using Formula 1, which is:

[0185]

[0186] In the formula:

[0187] K0—the coefficient of earth pressure at rest determined by the double-wedge method;

[0188] K h —Horizontal seismic coefficient;

[0189] —The internal friction angle of the back of the reinforced soil retaining wall.

[0190] The active earth pressure determined by the double-wedge method in S1 is calculated as follows:

[0191] The calculation diagram of the double wedge method is shown in the figure below. Figure 1 As shown, assuming that all forces are in a state of limit equilibrium, the area of ​​the reinforced soil retaining wall near the fill is defined as area B3, and the area of ​​the reinforced soil retaining wall near the monolithic panel 1 is defined as area F4. The reaction force of the sliding surface can be calculated according to the force equilibrium condition formula, and the earth pressure acting on the wall of the reinforced soil retaining wall can be obtained.

[0192] The reaction force in area B3 is calculated as follows:

[0193] Formula 2:

[0194] Formula 3:

[0195] The reaction force in region F4 is calculated as follows:

[0196] Formula 4:

[0197] Formula 5:

[0198] Formulas 2 through 5:

[0199] W B —Weight of wedge B, in kN / m;

[0200] W F —Weight of wedge F, in kN / m;

[0201] L B —Load acting on wedge B, unit: kN / m;

[0202] L F —Load acting on the wedge F, unit: kN / m;

[0203] P F —Resultant earth pressure, unit: kN / m;

[0204] P BF —Resultant earth pressure of wedge B, unit: kN / m;

[0205] R F —The reaction force at the bottom of the wedge F, in kN / m;

[0206] R B —The reaction force at the bottom of wedge B, in kN / m;

[0207] —The inner friction angle of the back wall of a reinforced soil retaining wall;

[0208] —Internal friction angle between wedges;

[0209] —The internal friction angle of the wedge-shaped packing;

[0210] —The internal friction angle of the wedge-shaped F-type packing;

[0211] θ B —Angle between the fracture surface of wedge B and the horizontal line;

[0212] θ BF —Angle between wedge B and the vertical line;

[0213] θ F —Angle between the fracture surface of wedge F and the horizontal line;

[0214] θ FW—The angle between the back of the reinforced soil retaining wall and the vertical line;

[0215] The equivalent uniformly distributed load of the reinforced soil retaining wall is calculated using Formula Six, which is:

[0216]

[0217] In the formula:

[0218] P Fx —Horizontal earth pressure exerted on the monolithic panel 1 by the double wedges, unit: kN;

[0219] H—Height of reinforced soil retaining wall, in meters;

[0220] M—Bending moment of reinforced soil retaining wall, unit: kN.m;

[0221] q1—Uniformly distributed stress at the top of the reinforced soil retaining wall, unit: kPa;

[0222] q2—Uniformly distributed stress at the bottom of the reinforced soil retaining wall, unit: kPa.

[0223] S2. To ensure the stability of the monolithic panel 1 under earth pressure, the earth pressure of the monolithic panel 1 obtained in the internal stability analysis and the load acting on the top of the reinforced soil retaining wall will be used as external forces to calculate the internal forces of the monolithic panel 1. The design will ensure that the stress generated in the monolithic panel 1 is within acceptable limits. The stress calculation model of the monolithic panel 1 and its reinforcing material 2 is as follows: Figure 2 and Figure 3 As shown;

[0224] Treating the monolithic panel 1 as a continuous beam and the stiffening material 2 as a spring fulcrum, calculate the combined design response value S of the monolithic panel 1 and the stiffening material 2. d Calculate the structural stress of the integral panel 1 and the stress of the reinforcing material 2.

[0225] Furthermore, in S2, the spring constant K of the stiffening material 2 used in the stress calculation of the integral panel 1 is... s Using the tensile force at 5% strain in the tension test, the spring constant K of the stiffener 2 is... s Calculated using Formula 7, Formula 7 is:

[0226] K s =a s ×T s / (0.05×L)

[0227] In the formula:

[0228] K s —The spring constant of reinforced material 2;

[0229] T s—Tensile strength of air-reinforced material 2 when stretched by 5% strain;

[0230] L—Standard length of reinforcing material 2. L can be selected as 15m in length. Unit: m;

[0231] a s —The correction factor for the constraint of reinforced material 2 is considered. Reinforced material 2 is constrained by the soil, and its value is larger than that obtained from the tension test, approximately 40 to 60 times that of the tension load test. Usually, when calculating the panel displacement, a is used. s =40 for calculation.

[0232] In S2, the method for calculating the structural forces of the monolithic panel 1 and the forces of the reinforcing material 2 is as follows:

[0233] Given that the loads on the monolithic panel 1 are q1, q2, ..., q i ,…q n+1 The rigidity of the integral panel 1 is EI, and the spring constant of the reinforcing material 2 is K. s Based on the elastically supported continuous beam, establish 2n+1 equations to form Formula 8, and calculate the 2n+1 bending moments and deformation values ​​(M1…M) at the junction of the stiffening material 2 and the monolithic panel 1. i …M n ,v1…v i …v n ,v n+1 Formula 8 is:

[0234]

[0235] In the formula,

[0236] M i —Bending moment at the junction of the reinforcing material 2 at point i and the monolithic panel 1, unit: kN / m;

[0237] v i —Deformation of the reinforcing material 2 at point i, in kN / m;

[0238] EI—Stiffness of Integral Panel 1, unit: kN / m 2 ;

[0239] q i —The earth pressure load stress at point i, where the reinforcement material is located, in kPa;

[0240] K s —The spring coefficient of reinforced material 2.

[0241] S3. Perform the pull-out design of the reinforcing material 2.

[0242] Furthermore, in S3: the ultimate limit state calculation of the crack bearing capacity of reinforced material 2 is performed according to formula nine, and the combined action design response value S d and structural resistance design value R d The expression is:

[0243] Formula 9: γ0S d ≤R d

[0244] In the formula:

[0245] γ0 — Structural importance coefficient;

[0246] S d —The combined action design response value mainly refers to deformation, cracks, etc.;

[0247] R d —Design value of structural resistance;

[0248] The combined design response value S of the reinforcement material at point i is as follows: di The structural resistance design value R of the reinforcement material 2 at point i. di The expression is as follows:

[0249] Formula 10: S di =K si ·v i

[0250] Formula 11: R di =T i =min(T) P ,T k )

[0251] In Formulas 10 and 11:

[0252] R di —Design value of structural resistance of the reinforcing material 2 at point i;

[0253] S di —Design response value of the reinforcement material 2 at point i;

[0254] K si —The spring constant of the reinforcing material 2 at point i;

[0255] T i —Design tensile force of reinforcing material 2, unit: kN / m;

[0256] T p —Tensile strength of reinforced material 2, unit: kN / m;

[0257] T k — Pull-out resistance of reinforced material 2, unit: kN / m;

[0258] Unlike anchor bolts and other materials with small deformation, reinforced material 2 will undergo larger horizontal deformation when subjected to horizontal thrust. Normal use deformation checks of reinforced material 2 can be performed according to Formulas XII and XIII.

[0259] Formula 12: S d ≤C

[0260] Formula Thirteen: S d =v i

[0261] In the formula:

[0262] C—The limit value specified for deformation, which is generally the corresponding limit value specified by the design for deformation, cracks, etc., 0.05L = 75mm.

[0263] S4. Calculate the reinforcement of monolithic panel 1.

[0264] Detailed calculations of stress in reinforced concrete monolithic panels can be performed by detailed design of the bending, shear, and crack resistance of the reinforced concrete members at each section. The specific design should be carried out in accordance with the "Standard for Design of Concrete Structures" (GB50010).

[0265] Furthermore, in S4, the detailed calculation of the stress of the reinforced concrete monolithic panel 1 can be achieved by designing the bending, shear, and crack resistance of the reinforced concrete members on each section of the monolithic panel 1. The design can be carried out in accordance with the "Standard for Design of Concrete Structures" (GB50010), including the following steps:

[0266] S41. Perform bending resistance calculations. For reinforced concrete members, perform crack bearing capacity ultimate state calculations according to Formula Nine.

[0267] Furthermore, the combined design response value S of the structural bending action in S41 is... d It is generally composed of a combination of earth pressure behind the wall, train dynamic load, groundwater pressure, seismic force, etc. For different design conditions, the individual components of the combined action effect can be calculated according to formulas fourteen to seventeen, and the partial factors are shown in Table 1:

[0268] Table 1 Partial Factors for the Effects of Ultimate Limit State Design of Structural Components

[0269]

[0270] In general areas and flooded areas with normal water levels, the basic combination in Table 1 can be used, and Formula Fourteen can be adopted:

[0271] S d =γ G S Gk +γ Q S Qk

[0272] In the formula:

[0273] S Gk —Bending moment or shear force generated by earth pressure;

[0274] S Qk — Bending moment or shear force generated by dynamic load;

[0275] γ G —Earth pressure effect coefficient using limit state design;

[0276] γ Q —Load action factor using limit state design;

[0277] When the flood level is under immersion conditions, the random combinations in Table 1 can be used, and Formula 15 can be applied:

[0278] S d =γ G S Gk +S wk +γ Q S Qk

[0279] In the formula:

[0280] S wk —Bending moment or shear force generated by water pressure;

[0281] Under seismic conditions, the seismic combinations in Table 1 can be used, and Formula Sixteen can be employed:

[0282] S d =γ G S Gk +γ I S Ek +γ Q S Qk

[0283] In the formula:

[0284] S Ek —The bending moment or shear force generated by the earthquake force;

[0285] γ I — Seismic action coefficients based on limit state design.

[0286] In S41, when the reinforced concrete flexural member has a rectangular cross-section, the structural resistance design value R is... d The calculation formula is Formula Seventeen:

[0287]

[0288] The height x of the concrete compression zone is determined according to Formula 18. Formula 18:

[0289] α1f c bx = f y A s -f′ y A′ s

[0290] The height x of the concrete compression zone meets the conditions of Formulas 19 and 20:

[0291] Formula 19: x≤ξ b h0

[0292] Formula 20: x≥2a′ s

[0293] Formulas 17 to 20:

[0294] a1 — coefficient, taken as 1.0;

[0295] f c —Design value of axial compressive strength of concrete;

[0296] f y —Design strength value for ordinary steel reinforcement;

[0297] A s —Cross-sectional area of ​​longitudinal ordinary reinforcing bars in the tension zone, unit: N / mm² 2 ;

[0298] A s — Cross-sectional area of ​​longitudinal ordinary reinforcing bars in the compression zone, unit: N / mm² 2 ;

[0299] b—Unit width of integral panel, unit: mm;

[0300] h0—Effective height of the integral panel section 1, unit: mm;

[0301] a′ s —The distance from the resultant point of the longitudinal reinforcing bars in the compression zone to the compression edge of the section, in mm;

[0302] ξ b —The relative limit compression zone height can be determined according to the "Code for Design of Concrete Structures" (GB50010-2010), unit: mm.

[0303] S42. Perform shear resistance calculation; the shear stress on the panel is as follows: Figure 2 , Figure 3 As shown, the ultimate limit state check of the shear bearing capacity of reinforced concrete members is performed according to Formula 9.

[0304] In S42, the combined action design response value S d Calculate according to formulas fourteen and fifteen;

[0305] In S42, when the reinforced concrete flexural member has a rectangular cross-section, the structural resistance design value R is... d The calculation formula is:

[0306] Formula 21: R d =0.025β c f c bh0

[0307] Where: β c —Concrete strength influence coefficient, taken as 1.0;

[0308] When stirrups or bent-up bars are used, the formula for calculating the design value of the shear resistance of the inclined section of a reinforced concrete flexural member with a rectangular cross-section is as follows:

[0309] Formula 22: R d =V cs +V bs

[0310] Formula 23:

[0311] Formula 24: V bs =0.8f yv A sb sinα s

[0312] Formulas 22 to 24:

[0313] V cs —Design values ​​of shear resistance of concrete and stirrups on the inclined section of the member;

[0314] V bs —Design value of tensile strength of bent-up reinforcement on the inclined section of the component;

[0315] α cv —The shear resistance coefficient of inclined concrete sections can be taken as 0.7 for general flexural members;

[0316] A sv —The total cross-sectional area of ​​each leg of the stirrups configured in the same cross section;

[0317] S— Spacing of stirrups along the length of the member;

[0318] f yv —Design value of tensile strength of stirrups or bent-up bars;

[0319] A sb —The cross-sectional area of ​​bent-up reinforcing bars in the same plane;

[0320] α s—The angle between the bent-up reinforcement on the inclined section and the longitudinal axis of the member.

[0321] S43. Crack checks are performed. Formula XII is used for the serviceability limit state design check of reinforced concrete members. In the design of retaining structures, foundation compressive stress, crack width, deflection, and displacement belong to this category.

[0322] In S43, the maximum crack width of reinforced concrete flexural members can be calculated according to the standard load combination or quasi-permanent combination, taking into account the long-term effects:

[0323] Formula 25:

[0324] Formula 26:

[0325] Formula 27:

[0326] Formula 28:

[0327] Formula 29:

[0328] Formulas 25 to 29:

[0329] α cr —The stress characteristic coefficient of the member is taken as 1.9 for reinforced concrete flexural members;

[0330] ψ—Coefficient of non-uniform strain of longitudinal tensile reinforcement between cracks: When ψ<0.2, take ψ=0.2; when ψ>1.0, take ψ=1.0; for members directly subjected to repeated loads, take ψ=1.0;

[0331] σ sq —Longitudinal tensile reinforcement stress in reinforced concrete members calculated according to the quasi-permanent load combination, unit: N / mm 2 ;

[0332] E s —Elastic modulus of reinforcing steel, unit: N / mm 2 Select according to Appendix B of the "Code for Design of Railway Subgrade Retaining Structures" (TB10025);

[0333] c s —The distance from the outermost longitudinal tensile reinforcement to the bottom edge of the tension zone, in mm; when c s When <20mm, take c s =20mm, when c s When the diameter is >65mm, take c. s =65mm;

[0334] d eq—Equivalent diameter of longitudinal reinforcement in the tension zone, unit: mm;

[0335] ρ te —The longitudinal tensile reinforcement ratio calculated based on the effective tensile concrete cross-sectional area, when ρ te When ρ < 0.01, take ρ te =0.01;

[0336] f tk —Standard value of axial tensile strength of concrete, unit: N / mm² 2 Select according to Appendix A of the "Code for Design of Railway Subgrade Retaining Structures" (TB10025);

[0337] A s —Cross-sectional area of ​​longitudinal ordinary reinforcing bars in the tension zone, unit: N / mm² 2 ;

[0338] h0—Effective height of the cross section, unit: mm;

[0339] A te —Effective tensile concrete cross-sectional area, unit: N / mm² 2 For T-section bending members with rectangular and flange compression, take A. te =0.5bh;

[0340] d i —The nominal diameter of the i-th type of longitudinal tensile reinforcement in the tension zone, in mm;

[0341] n i —The number of the i-th type of longitudinal tensile reinforcement bars in the tension zone;

[0342] v i —The relative bond characteristic coefficient of the i-th type of longitudinal reinforcement in the tension zone, which is 0.7 for smooth reinforcement and 1.0 for ribbed reinforcement;

[0343] In Formula 27, M q When using standard combinations,

[0344] S d =S Gk +S Qk

[0345] In Formula 27, M q When using quasi-permanent combinations,

[0346] S d =S Gk +ψ q S Qk

[0347] In the formula:

[0348] ψq —The quasi-permanent value coefficient for variable actions can be determined based on observational data and engineering experience, ψ q ≥0.6.

[0349] Example 2

[0350] This embodiment adopts the integral panel structure design method for reinforced soil retaining walls provided in Embodiment 1, wherein the calculation parameters of the integral panel 1 of the reinforced soil retaining wall are shown in Table 2.

[0351] Table 2 Design parameters for geotechnical engineering and retaining walls

[0352]

[0353] S1. Calculate the earth pressure on the integral panel 1.

[0354] refer to Figures 1-4 As shown, the reaction force in region B3 is calculated as follows:

[0355]

[0356]

[0357] The reaction force in region F4 is calculated as follows:

[0358]

[0359]

[0360] The equivalent uniformly distributed stress is calculated as follows:

[0361]

[0362] M = P Fx ·H / 3=86.05×5.8 / 3=166.36kN·m

[0363]

[0364] S2. Calculate the structural forces on the monolithic panel 1 and the forces on the reinforcing material 2.

[0365] The spring constant K of the stiffening material 2 used in the stress calculation of the integral panel 1 s The tensile force at 5% strain in the tension test is used, that is:

[0366] K s =a s ×T s / (0.05×L)=40×30 / (0.05×1.5)=16000kN / m

[0367] Given that the loads on the monolithic panel 1 are q1, q2, ..., q i ,…q n+1 The rigidity of the integral panel 1 is EI, and the spring constant of the reinforcing material 2 is K. s Based on the elastically supported continuous beam, establish 2n+1 equations to form Formula 8, and calculate the 2n+1 bending moments and deformation values ​​(M1…M) at the junction of the stiffening material 2 and the monolithic panel 1. i …M n ,v1…v i …v n ,v n+1 Formula 8 is:

[0368]

[0369] The specific calculation results are shown in Table 3.

[0370] Table 3. Structural stress and reinforcement material stress calculation for integral panel.

[0371]

[0372]

[0373] Table 4 Pull-out Calculation Table for Reinforced Materials

[0374]

[0375] S3. Perform the pull-out design of the reinforcing material 2.

[0376] The ultimate limit state calculation of the crack bearing capacity of reinforced material 2 was performed according to Formula 9; the normal service deformation calculation of reinforced material 2 was performed according to Formulas 12 and 13. The calculation results are shown in Table 4.

[0377] S4. Calculate the reinforcement of monolithic panel 1.

[0378] Detailed calculation of the stress of the monolithic reinforced concrete panel 1 can be achieved by detailed design of the bending resistance, shear resistance, and crack resistance of the reinforced concrete members on each section. The specific design should be carried out in accordance with the "Standard for Design of Concrete Structures" (GB50010). The reinforcement calculation results of the monolithic panel 1 structure are shown in Table 5.

[0379] Table 5. Calculation results of reinforcement for monolithic panel structures

[0380] project Steel reinforcement usage Main reinforcement Φ10@125 stirrups Φ8@200 Maximum crack 0.019mm<0.200mm

[0381] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A design method for an integral panel structure for reinforced soil retaining walls, characterized in that, Includes the following steps: S1. Calculate the earth pressure on the monolithic panel (1). The earth pressure on the monolithic panel (1) is the resultant earth pressure P calculated using the double wedge method and formula four. F ; S2. Using the earth pressure of the integral panel (1) and the load acting on the top of the reinforced soil retaining wall as external forces, calculate the internal forces of the integral panel (1); Treat the integral panel (1) as a continuous beam, and the reinforcing material (2) of the integral panel (1) as a spring fulcrum. Calculate the combined design response value of the integral panel (1) and the reinforcing material (2), and calculate the structural stress of the integral panel (1) and the stress of the reinforcing material (2). S3. Perform the pull-out design of the reinforcing material (2); S4. Calculate the reinforcement of the monolithic panel (1); The at-rest earth pressure coefficient determined by the double-wedge method in S1 is calculated using Formula 1, which is: In the formula: —The coefficient of earth pressure at rest determined by the double-wedge method; —Horizontal seismic coefficient; —Inner friction angle of reinforced soil retaining wall, unit: °; The active earth pressure determined by the double-wedge method in S1 is calculated as follows: Assuming all forces are in a state of limit equilibrium, the area of ​​the reinforced soil retaining wall near the fill is defined as zone B (3), and the area of ​​the reinforced soil retaining wall near the monolithic panel (1) is defined as zone F (4). The reaction force of zone B (3) is calculated as follows: Formula 2: ; Formula 3: ; The reaction force in region F (4) is calculated as follows: Formula 4: ; Formula 5: ; Formulas 2 through 5: —Weight of wedge B, in kN / m; —Weight of wedge F, in kN / m; —Load acting on wedge B, unit: kN / m; —Load acting on the wedge F, unit: kN / m; —Resultant earth pressure, unit: kN / m; —Resultant earth pressure of wedge B, unit: kN / m; —The reaction force at the bottom of the wedge F, in kN / m; —The reaction force at the bottom of wedge B, in kN / m; —Inner friction angle of reinforced soil retaining wall, unit: °; —Internal friction angle between wedges, unit: °; —Internal friction angle of wedge B packing, unit: °; —Internal friction angle of wedge F packing, unit: °; —Angle between the fracture surface of wedge B and the horizontal line, unit: °; —Angle between wedge B and the vertical line, unit: °; —Angle between the fracture surface of wedge F and the horizontal line, unit: °; —Angle between the back of the reinforced soil retaining wall and the vertical line, unit: °; The equivalent uniformly distributed stress of the reinforced soil retaining wall is calculated using Formula Six, which is: ； In the formula: —Horizontal earth pressure on the double wedge body of the integral panel (1), unit: kN; —Height of reinforced soil retaining wall, in meters; — Bending moment of reinforced soil retaining wall, unit: kN.m; —Uniformly distributed stress at the top of the reinforced soil retaining wall, unit: kPa; —Uniformly distributed stress at the bottom of the reinforced soil retaining wall, unit: kPa; In S2, the spring coefficient of the reinforcing material (2) is calculated using Formula 7, which is: In the formula: —Spring coefficient of the reinforcing material (2), unit: kN / m 2 ; —Tensile strength of air-reinforced material (2) at 5% strain, unit: kN / m; —Standard length of the reinforcing material (2), in meters; —Reinforced material (2) Considering the correction factor for constraints; In S2, the method for calculating the structural stress of the integral panel (1) and the stress of the reinforcing material (2) is as follows: Based on the elastically supported continuous beam, establish 2n+1 equations to form Formula 8, and calculate the 2n+1 bending moments and deformation values ​​at the junction of the reinforced material (2) and the integral panel (1). Formula 8 is as follows: In the formula, —No. i Bending moment at the junction of the point-reinforced material (2) and the monolithic panel (1), unit: kN / m; —No. i Deformation of the point-reinforced material (2), unit: m; —Stiffness of integral panel (1), unit: kN / m 2 ; —No. i Earth pressure load stress at point reinforcement material (2), unit: kPa; —The spring coefficient of the reinforced material (2).

2. The method for designing an integral panel structure for reinforced soil retaining walls according to claim 1, characterized in that, S3 includes the following steps: The ultimate limit state calculation of the crack bearing capacity of the reinforced material (2) is performed according to Formula 9. Formula 9 is: In the formula: —Structural importance coefficient; —Combined action design response value; —Design value of structural resistance; The expressions for the combined action design response value of the reinforcing material (2) at point i and the structural resistance design value of the reinforcing material (2) at point i are as follows: Formula 10: Formula 11: In Formulas 10 and 11: —No. i Design value of structural resistance of point-reinforced material (2); —No. i The combined design response value of the point-reinforced material (2); —No. i The spring constant of the point-reinforced material (2); —Design tensile force of the reinforcing material (2), unit: kN / m; —Tensile strength of the reinforcing material (2), unit: kN / m; — Pull-out resistance of the reinforcing material (2), unit: kN / m; According to Formulas 12 and 13, the reinforcing material (2) is designed for normal use under deformation conditions: Official 12: Formula Thirteen: In the formula: —The limits specified for deformation.

3. The method for designing an integral panel structure for reinforced soil retaining walls according to claim 2, characterized in that, S4 calculates the reinforcement of the monolithic panel (1), which involves designing the bending, shear, and crack resistance of the reinforced concrete members on each section of the monolithic panel (1), including the following steps: S41. Perform bending resistance calculation. The reinforced concrete member shall be checked for crack bearing capacity ultimate limit state according to Formula 9. S42. Perform shear resistance check. The reinforced concrete member shall be checked for ultimate shear capacity according to Formula 9. S43. Crack calculation is performed, and the serviceability limit state design of the reinforced concrete member adopts Formula Twelve.

4. The method for designing an integral panel structure for reinforced soil retaining walls according to claim 3, characterized in that, S41 The calculation formula is: For normal water levels in general areas and flooded areas, Formula Fourteen is used: In the formula: —Bending moment or shear force generated by earth pressure; — Bending moment or shear force generated by dynamic load; —Earth pressure effect coefficient using limit state design; —Load action factor using limit state design; When the flood level is under immersion conditions, Formula 15 is used: In the formula: —Bending moment or shear force generated by water pressure; In earthquake conditions, Formula Sixteen is used: In the formula: —The bending moment or shear force generated by the earthquake force; —Seismic action coefficients based on limit state design; S41 The calculation formula is Formula Seventeen: Concrete compression zone height x Determined according to Formula 18, Formula 18: Concrete compression zone height x The conditions of Formula 19 and Formula 20 are met: Formula 19: Formula 20: Formulas 17 to 20: — Coefficient, set to 1.0; —Design value of axial compressive strength of concrete; —Design strength value for ordinary steel reinforcement; —Cross-sectional area of ​​longitudinal ordinary reinforcing bars in the tension zone, unit: ; —Cross-sectional area of ​​longitudinal ordinary reinforcing bars in the compression zone, unit: ; —Integral panel (1) unit width, unit: mm; —Effective height of integral panel (1) section, unit: mm; —The distance from the resultant point of the longitudinal reinforcing bars in the compression zone to the compression edge of the section, in mm; —Relative limit pressure zone height, unit: mm.

5. The method for designing an integral panel structure for reinforced soil retaining walls according to claim 4, characterized in that, In S42, the combined action design response value is calculated according to Formula XIV and Formula XV; S42 in The calculation formula is: Formula 21: In the formula: —Concrete strength influence coefficient, taken as 1.0; When stirrups or bent-up bars are used, the formula for calculating the design value of the shear resistance of the inclined section of a reinforced concrete flexural member is as follows: Formula 22: Formula 23: Formula 24: Formulas 22-24: —Design values ​​of shear resistance of concrete and stirrups on the inclined section of the member; —Design value of tensile strength of bent-up reinforcement on the inclined section of the component; —Shear resistance coefficient of inclined concrete section; —The total cross-sectional area of ​​each leg of the stirrups configured in the same cross section; — Spacing of stirrups along the length of the member; —Design value of tensile strength of stirrups or bent-up bars; —The cross-sectional area of ​​bent-up reinforcing bars in the same plane; —The angle between the bent-up reinforcement on the inclined section and the longitudinal axis of the member.

6. The method for designing an integral panel structure for reinforced soil retaining walls according to claim 5, characterized in that, In S43, the formula for calculating the maximum crack width is as follows: Formula 25: Formula 26: Formula 27: Formula 28: Formula 29: Formulas 25 to 29: —Component stress characteristic coefficient; —Coefficient of non-uniform strain of longitudinal tensile reinforcement in cracks; —Longitudinal tensile reinforcement stress in reinforced concrete members calculated based on quasi-permanent load combinations, unit: ; —Elastic modulus of reinforcing steel, unit: ; —The distance from the outermost longitudinal tensile reinforcement to the bottom edge of the tension zone, in mm; —Equivalent diameter of longitudinal reinforcement in the tension zone, unit: mm; —The longitudinal tensile reinforcement ratio calculated based on the effective tensile concrete cross-sectional area; This is the standard value of the axial tensile strength of concrete, in units of: ; —Cross-sectional area of ​​longitudinal ordinary reinforcement in the tension zone, unit: ; —Effective height of the cross section, unit: mm; —Effective tensile concrete cross-sectional area, unit: ; —The first district of the affected area i The nominal diameter of longitudinal tensile reinforcement bars, in mm; —The first district of the affected area i The number of longitudinal tensile steel bars; —The first district of the affected area i The relative bond characteristic coefficient of longitudinal reinforcement; In Formula 27, When using standard combinations, In Formula 27, When using quasi-permanent combinations, In the formula: —The quasi-permanent value coefficient of variable action, .

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