Method for Calculating the Tensile Force of Reinforced Body in Reinforced Cushion Layer of Pile-Net Composite Foundation

Abstract

This invention discloses a method for analyzing and calculating the tensile force of reinforced bodies in a reinforced cushion layer of a pile-net composite foundation, comprising: S1, obtaining the basic parameters of the pile-net composite foundation according to the design scheme of the pile-net composite foundation, including embankment parameters and reinforced foundation parameters; S2, calculating the average stress of the soil between piles at the pile top plane of the pile-net composite foundation based on the embankment parameters and reinforced foundation parameters; S3, calculating the average ground reaction force at the base of the reinforced cushion layer of the pile-net composite foundation; S4, calculating the total tensile force of the reinforced bodies caused by vertical loads based on the average stress of the soil between piles obtained in S2 and the average ground reaction force obtained in S3; S5, calculating the total tensile force of the reinforced bodies caused by the slope thrust effect; S6, calculating the tensile force of each layer of reinforced bodies in the reinforced cushion layer of the pile-net composite foundation. This method is applicable to more complex application scenarios and is a means of calculating the tensile force of reinforced bodies in reinforced cushion layers with both high calculation efficiency and accuracy.

Description

Technical Field

[0001] This invention relates to the field of design of reinforced cushion layers for pile-net composite foundations in roadbed engineering, and in particular to a method for analyzing and calculating the tensile force of the reinforcing body in a pile-net composite foundation reinforced cushion layer. Background Technology

[0002] Pile-net composite foundations are a commonly used foundation reinforcement structure in railway subgrade engineering. They have advantages such as small settlement deformation, short stabilization time, easy quality control, and good economy, and are widely used in subgrade reinforcement projects in deep soft soil areas. In order to effectively homogenize the load of the superfill soil, reduce stress concentration at the pile top and pile cap edges, improve the overall bearing capacity of the pile-net composite foundation, and reduce the overall settlement, the cushion layer structure set at the pile top position generally needs to be reinforced with one or more layers of geogrid.

[0003] The reinforced cushion layer of the pile-grid composite foundation consists of two parts: large-diameter granular materials (sand, gravel, medium-coarse sand, etc.) and geogrid reinforcement. The granular materials can only transmit compressive stress, while the geogrid reinforcement can bear tensile force, better constraining the deformation of the granular materials and significantly improving the overall performance of the reinforced cushion layer. The calculation and control of the tensile force of the reinforcement is a key aspect of reinforced cushion layer design, directly determining the number of reinforcement layers required and the selection of their mechanical properties. Especially for multi-layer reinforced cushion layers, the placement of the reinforcement is directly related to the magnitude of the tensile force; generally, the strain of the lower layer is greater than that of the upper layer, and correspondingly, the tensile force of the bottom layer is also greater. Therefore, how to calculate the tensile force of each layer of geogrid reinforcement and ensure that the mechanical properties of the geogrid meet the requirements is a key technical issue that needs to be focused on in the engineering design of reinforced cushion layers.

[0004] At present, the calculation methods for the tensile force of the reinforced body in the reinforced cushion layer are mainly based on the soil arch theory and the tension membrane theory. However, these methods are only applicable to the case of single-layer reinforced body and cannot reflect the uneven distribution effect of multi-layer reinforced body on the total tensile force, thus failing to meet the design requirements of railway subgrade engineering. Summary of the Invention

[0005] To address the problems in the background art, the present invention provides a method for calculating the tensile force of reinforced bodies in pile-net composite foundation reinforced cushion layers, which can calculate the stress conditions of multi-layered reinforced bodies and whose calculation results are accurate, effective, and highly consistent with actual conditions.

[0006] Therefore, the present invention adopts the following technical solution:

[0007] A method for analyzing and calculating the tensile force of reinforcement in a reinforced cushion layer of a pile-mesh composite foundation includes the following steps:

[0008] S1. Obtain the basic parameters of the pile-net composite foundation based on the design scheme of the pile-net composite foundation, including the parameters of the embankment and the parameters of the reinforced foundation;

[0009] S2, Calculate the average stress between piles in the soil at the top plane of the pile-mesh composite foundation based on the embankment parameters and reinforced foundation parameters. :

[0010] S3, Calculate the average ground reaction force at the reinforced cushion layer base of the pile-net composite foundation. ;

[0011] S4, the average stress of the soil between piles obtained from S2. The average ground reaction force obtained from S3 Calculate the total tensile force of the stiffened body caused by vertical load. ;

[0012] S5, Calculate the total tensile force of the reinforced body caused by the slope thrust effect. ;

[0013] S6, obtained from S4 And S5 Calculate the tensile force of each layer of reinforcement in the reinforced cushion layer of the pile-mesh composite foundation. .

[0014] The tensile force of each layer of stiffeners described in S6 Calculated using the following formula:

[0015] ,

[0016] in:

[0017] For the first The first distribution coefficient of the layered reinforced body , This refers to the layer number of the reinforcing body in the reinforced pad layer. At that time, it was the top layer of reinforced structure; The proportionality coefficient for the tensile force in the reinforced body caused by vertical loads is determined based on the actual situation;

[0018] To calculate the first The second distribution coefficient for layered reinforced structures. .

[0019] The sum of the first distribution coefficients of all reinforced cushion layers in step S6 is 1.0; the sum of the second distribution coefficients of all reinforced cushion layers is also 1.0. .

[0020] The embankment parameters mentioned in step S1 include the embankment height. , fill density Comprehensive internal friction angle of embankment fill Embankment slope and the static load on the top surface of the embankment ;

[0021] The parameters for strengthening the foundation include: pile spacing. Clear distance between piles Circular pile cap diameter Equivalent square pile cap side length Porosity of reinforced mesh The internal friction angle of the reinforced cushion layer bearing the foundation soil and the total number of reinforced layers in the reinforced cushion layer .

[0022] The average stress acting on the soil between piles ,in, The average stress caused by the static load on the embankment fill. The average stress is caused by the dynamic stress of the distributed load on the train.

[0023] The average stress caused by the static load of the embankment fill in step S2 The calculation is performed using a spherical soil arch model, and the formula is as follows:

[0024] ;

[0025] In the formula:

[0026] For exponential parameters, ; The passive earth pressure coefficient of embankment fill;

[0027] and These are the parameters for pile placement. , ;

[0028] The height of the earthen arch, .

[0029] The average stress caused by the dynamic stress of the train distributed load in step S2 is calculated. First, determine the height of the earth embankment. If the height of the earth embankment is greater than 3m, then... Otherwise, the Boussinesq line load integral is used for calculation, as shown in the following formula:

[0030] ;

[0031] in, Train load distribution on the roadbed surface; and These are the vertical distance and the distance between the additional stress calculation point and the micro-segment of the train's distributed load, respectively; The coordinates of the start and end points of the train load distribution on the roadbed surface; All are determined based on the design scheme in S1.

[0032] Average ground reaction force in step S3 Calculated using the following formula:

[0033] ;

[0034] in, The overall foundation stiffness of the pile-net composite foundation; To control strain in reinforced bodies, .

[0035] Total tensile force of the stiffened body in step S4 Calculated using the following formula:

[0036] ;

[0037] in, ; , To control strain in reinforced bodies, .

[0038] Total tensile force of the stiffened body in step S5 Calculated using the following formula:

[0039] ;

[0040] in, This is the active earth pressure coefficient of the embankment fill.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. In this invention, the calculation of the tensile force of the reinforced body in the reinforced cushion layer of the pile-net composite foundation is divided into two parts: the tensile force caused by the vertical load and the tensile force caused by the thrust of the embankment slope. According to the distribution characteristics of the two types of tensile forces, the tensile force of the reinforced body at different locations is determined by the proportional decreasing method and the average distribution method, respectively, so as to satisfy the calculation of the tensile force of the reinforced body in single-layer and multi-layer reinforced cushion layers with any number of layers.

[0043] 2. In the method of the present invention, all formulas used in the solution process are explicit analytical expressions, and the validity of the solution results can be manually verified. The entire solution process is more scientific, direct, effective and accurate. The solution process is more standardized and applicable to more complex application scenarios. It is a means of calculating the tensile force of the reinforced body in the reinforced cushion layer with high calculation efficiency and accuracy.

[0044] 3. In this invention, the tensile force calculation parameters of the reinforced body of the reinforced cushion layer are all commonly used geotechnical parameters, which are easy to obtain and have been verified by many engineering designs. They are more convenient to apply to the design of reinforced cushion layers for pile-net composite foundations in railway subgrade engineering. The obtained tensile force of the reinforcement can be used to select appropriate reinforcement materials. It can also be used to determine whether the number of reinforcement layers currently laid meets the tensile force requirements, thereby increasing or decreasing the number of reinforcement layers. Attached Figure Description

[0045] Figure 1 This is a flowchart of the method of the present invention;

[0046] Figure 2 This is a schematic diagram of the spherical soil arch and reinforced cushion layer bearing capacity of the pile-net composite foundation;

[0047] Figure 3 This is a schematic diagram showing the relative positional relationship between the spherical soil arch and the multi-layered reinforced cushion layer of the pile-net composite foundation;

[0048] Figure 4 This is a schematic diagram of the stress on the upper and lower surfaces of the reinforced pad layer;

[0049] Figure 5 This is a schematic diagram for calculating the different forces acting on the reinforced body in the reinforced cushion layer caused by vertical loads;

[0050] Figure 6 This is a schematic diagram of the different forces acting on the reinforced body in the reinforced cushion layer caused by the slope thrust effect;

[0051] In the diagram: 1. Embankment, 2. Rigid pile, 3. Pile cap, 4. Spherical soil arch, 5. Reinforced cushion layer, 6. Reinforced body. Detailed Implementation

[0052] The following describes in detail, with reference to the accompanying drawings, the method for analyzing and calculating the tensile force of the reinforcement body in the reinforced cushion layer of the pile-net composite foundation of the present invention.

[0053] See Figure 1 The method of the present invention includes the following steps:

[0054] S1, Determine the basic parameters of the pile-net composite foundation:

[0055] Based on the design scheme of the pile-net composite foundation, the basic parameters of the pile-net composite foundation are obtained. The basic parameters include the parameters of the embankment and the parameters of the reinforced foundation, among which:

[0056] The parameters for the earth-filled embankment include the embankment height. , fill density Comprehensive internal friction angle of embankment fill Embankment slope and the static load on the top surface of the embankment ;

[0057] The parameters for strengthening the foundation include: pile spacing. Clear distance between piles Circular pile cap diameter Equivalent square pile cap side length Porosity of reinforced mesh The internal friction angle of the reinforced cushion layer bearing the foundation soil and the total number of reinforced layers in the reinforced cushion layer .

[0058] Specifically: according to Figure 2 The composition of the pile-net composite foundation type of the mounted subgrade is determined, and the relevant embankment parameters and reinforced foundation parameters in the embankment 1 are determined respectively.

[0059] (1) Embankment height The distance from the top surface of the pile cap 3, located at the top of the rigid pile 2, to the top surface of the embankment 1, is the unit weight of the fill soil. The wet density of the fill material in its natural state, and the slope of the embankment. Determined based on the ratio of the horizontal projection length of the embankment slope to the height of the embankment slope;

[0060] (2) Comprehensive internal friction angle of embankment fill Suitable for cohesive or non-cohesive soil fillers;

[0061] When the embankment fill is cohesive soil, the internal friction angle of the fill should be determined based on the embankment slope height. and cohesion according to Convert to equivalent internal friction angle;

[0062] When the embankment fill is non-cohesive soil, the comprehensive internal friction angle of the embankment fill is... Angle of friction with backfill same.

[0063] (3) Calculate the static load on the top surface of the embankment First, determine the ancillary loads on the embankment slope, such as those for tracks, track spacing, and cable troughs. Then, based on the actual distribution width of each type of load, convert them into equivalent static loads on the top surface. ;

[0064] (4) Pile spacing The center-to-center distance between adjacent piles, and the net distance between piles. The net distance between adjacent piles or pile caps;

[0065] (5) Determine the diameter of the circular pile cap according to the type of pile cap installed on the pile top. Or the side length of a square pile cap The two satisfy the equivalent conversion relationship of equation (1):

[0066] (1)

[0067] (6) Determine the number of reinforcement layers based on the actual number of multi-layer reinforcement bodies 6 set in the reinforced cushion layer 5 at the top of the rigid pile 2. Other parameters are determined according to the design scheme.

[0068] S2, Calculate the average stress in the soil between piles at the top plane of the pile-net composite foundation. :

[0069] according to Figure 3 The relative positional relationship between the spherical soil arch 4 and the reinforced cushion layer 5 in the pile-net composite foundation and Figure 4 The stress on the upper and lower surfaces of the reinforced cushion layer, taking into account the combined effects of the static load of the embankment fill and the dynamic load of the train, yields the average stress of the soil between the piles. ;

[0070] Average stress in the soil between piles Average stress caused by static load of embankment fill Mean stress caused by dynamic stress It consists of two parts, namely .

[0071] Among them, the average stress caused by the static load of the embankment fill in the first part. The calculation was performed using a spherical earth arch model:

[0072] (2)

[0073] In the formula:

[0074] For exponential parameters, ;

[0075] The passive earth pressure coefficient of embankment fill;

[0076] and These are the parameters for pile placement. , ;

[0077] The height of the earthen arch, ;

[0078] Calculate the average stress caused by the dynamic stress of the distributed train load in Part 2. If the embankment height is greater than 3.0m, the dynamic stress of the train will be significantly attenuated in the roadbed. Therefore, the influence of the dynamic stress of the distributed train load is neglected. Otherwise, use the Boussinesq line load integral to... The calculation is performed as shown in equation (3):

[0079] (3)

[0080] in, Train load distribution on the roadbed surface; and These are the vertical distance and the distance between the additional stress calculation point and the micro-segment of the train's distributed load, respectively; The coordinates of the start and end points of the train load distribution on the roadbed surface; All are determined based on the design scheme.

[0081] In addition, the average stress caused by the dynamic stress of the distributed load on the train The average vertical stress of the reinforced body within the pile spacing range is taken.

[0082] S3, Calculate the average ground reaction force at the reinforced cushion layer base of the pile-net composite foundation. :

[0083] according to Figure 4 A schematic diagram of the forces acting on the upper and lower surfaces of the reinforced cushion layer 5. The reinforced cushion layer 5 bears the load on the elastic foundation under the vertical load on the upper surface. The average ground reaction force at the base of the reinforced cushion layer 5 in the pile-mesh composite foundation is shown. Determined using the elastic foundation reaction method:

[0084] Specifically, it is first assumed that the reinforced cushion layer 5 deforms in the form of a catenary deformation. Based on the catenary deformation morphology characteristics of the reinforced body 6 and the strain control of the reinforced body, Determine the mid-span deflection of the reinforced body Among them, the mid-span deflection of the reinforced structure. Control of strain with stiffened body The relationship between them satisfies equation (4):

[0085] (4)

[0086] Then, based on the control strain of the reinforced body in the reinforced cushion layer and the net distance between piles, the average reaction force of the foundation at the base of the reinforced cushion layer is obtained by using the method of calculating the reaction force of the flexible foundation on the elastic foundation. That is, equation (5);

[0087] (5)

[0088] In the formula, The overall foundation stiffness of the pile-net composite foundation; To control strain in reinforced structures, a strain rate of 4% to 6% is generally used.

[0089] S4, Calculate the total tensile force of the reinforced body caused by the vertical load. :

[0090] according to Figure 5 A schematic diagram illustrating the calculation of the total tensile force of the reinforced body in the reinforced cushion layer caused by vertical loads. The multi-layered reinforced body 6 in the reinforced cushion layer 5 is treated as a single layer, and the deformation of the reinforced body under vertical loads is assumed to be a catenary. The average stress caused by the static load on the embankment fill, determined based on S2 and S3, is also included. Average stress caused by dynamic stress of distributed load on train and the average ground reaction force of the reinforced foundation layer. This allows for the determination of the average stress borne by the reinforced body in the reinforced cushion layer. ; Specifically, it is the net load on the reinforced cushion layer after deducting the average reaction force of the foundation, which acts on the upper surface of an equivalent reinforced body.

[0091] Then, in the calculation of the total tensile force of the reinforced body caused by vertical load, the multi-layered reinforced body in the reinforced cushion layer is treated as a single layer. Based on the deformation characteristics of the reinforced body under vertical load, the catenary theory is used to calculate the total tensile force of the reinforced body. ;

[0092] (6)

[0093] (7)

[0094] S5, Calculate the total tensile force of the reinforced body caused by the slope thrust effect. :

[0095] according to Figure 6 A schematic diagram illustrating the calculation of the total tensile force of the reinforced body in the reinforced cushion layer caused by slope thrust effect. Combining the bearing capacity of the reinforced body in the pile-mesh composite foundation, and comprehensively considering the combined influence of the lateral thrust caused by the active earth pressure of the embankment slope and the base skin friction of the reinforced cushion layer on the tensile force of the reinforced body, the total tensile force of the reinforced body in the reinforced cushion layer caused by slope thrust effect is obtained through the balance relationship of the horizontal forces in the reinforced cushion layer. As shown in equation (8):

[0096] (8)

[0097] In the formula, The active earth pressure coefficient for embankment fill;

[0098] The calculation of the horizontal thrust effect on the slope adopts the active earth pressure calculation method, and the active earth pressure coefficient is... Rankine's active earth pressure coefficient or Coulomb's earth pressure coefficient can be used. The horizontal thrust is applied at the vertical section of the shoulder corner of the embankment slope. In addition, in establishing the balance relationship of the horizontal force of the reinforced cushion layer, the determination of the base friction of the reinforced cushion layer should take into account the influence of the self-weight of the embankment slope. The friction coefficient is determined by the internal friction angle of the foundation soil supported by the reinforced cushion layer.

[0099] S6, Calculate the tensile force of each layer of reinforcement in the reinforced cushion layer of the pile-net composite foundation:

[0100] First, the common in the reinforced cushion layer The reinforcement layers are numbered from bottom to top, with the bottom layer being layer 1 and the top layer being layer 2. The first vertical load caused by the first vertical load Tensile distribution coefficient of reinforced layer The tensile force of each layer decreases proportionally from bottom to top, and the first distribution coefficient of the tensile force of each layer of stiffeners is... The sum is 1.0. ,have:

[0101] (9)

[0102] In the formula, q is the proportionality coefficient of the tensile force of the stiffened body caused by the vertical load, which is determined according to the actual situation;

[0103] Then, the slope thrust effect caused the first Tensile distribution coefficient of layered reinforced body Based on the number of reinforced layers The distribution is determined by equal division, and the second distribution coefficient of the tensile force of each layer of stiffeners is determined by equal division. The sum is 1.0, therefore:

[0104] (10)

[0105] Finally, based on the total tensile force of the reinforced body caused by the vertical load... Total tensile force of reinforced body caused by slope thrust effect Considering the differences in the tensile force distribution coefficient of the reinforced body at different locations in the multi-layered reinforced pad, the following can be obtained: Tensile strength of layered reinforced body ;

[0106] (11) Example

[0107] To facilitate understanding and application by technical personnel in this industry, the following examples are provided, including determining the basic parameters of the pile-net composite foundation for embankment filling and reinforced foundation, calculating the average stress between piles in the pile top plane of the pile-net composite foundation, determining the average reaction force of the foundation at the base of the reinforced cushion layer of the pile-net composite foundation, calculating the total tensile force of the reinforced body caused by vertical load, determining the total tensile force of the reinforced body caused by slope thrust effect, and determining the tensile force of each layer of the reinforced cushion layer of the pile-net composite foundation. Finally, the tensile force of each layer of the reinforced cushion layer of the pile-net composite foundation is obtained.

[0108] Unless otherwise specified, the units of measurement for all process or calculation parameters involved in the following calculation methods shall be in standard units.

[0109] S1, Determine the basic parameters of the pile-net composite foundation:

[0110] (1) Obtain the parameters of the earth-filled embankment:

[0111] Embankment fill height ;

[0112] Embankment fill density ;

[0113] Comprehensive internal friction angle of embankment fill ;

[0114] Embankment fill slope

[0115] Equivalent external load on embankment surface

[0116] (2) Obtain embankment reinforcement parameters

[0117] Pile spacing ;

[0118] Clear distance between piles ;

[0119] Pile cap diameter ;

[0120] The side length of a round pile cap is equivalent to that of a square pile cap. ;

[0121] Number of geogrid layers ;

[0122] Reinforced cushion layer bearing the internal friction angle of foundation soil ;

[0123] Geogrid porosity .

[0124] S2, Calculate the average stress in the soil between piles at the top plane of the pile-net composite foundation. :

[0125] The calculation of the average acting stress on the pile top plane of the pile-net composite foundation is mainly based on the spherical soil arch model, neglecting the influence of the reinforced cushion layer on the spherical soil arch action. The calculation parameters and results are as follows:

[0126] Earth arch height : ;

[0127] Passive earth pressure coefficient K of embankment fill p :K p =[tan(0.25π+φ / 2)] 2 =3.00;

[0128] Staking parameters : ;

[0129] Staking parameters : ;

[0130] Exponential parameters : ;

[0131] Average stress of soil between piles at pile top plane ;

[0132] Embankment height Since the length is 4.8m, which is greater than 3.0m, and the influence of train dynamic load is not considered, the vertical stress of the stiffened body caused by train dynamic load is... .

[0133] S3, Calculate the average ground reaction force at the reinforced cushion layer base of the pile-net composite foundation. :

[0134] The calculation of the average reaction force of the foundation soil at the reinforced cushion layer of the pile-net composite foundation is based on an elastic foundation model. According to the aforementioned analysis process, the comprehensive foundation stiffness of the reinforced foundation is... Take 100kN / m 3 ;

[0135] The stiffeners in the reinforced cushion layer control strain ;

[0136] Mid-span deflection of reinforced pad : ;

[0137] Average reaction force of foundation : .

[0138] S4, Calculate the total tensile force of the reinforced body caused by the vertical load. :

[0139] Based on the calculation process of the tensile force of the reinforced body in the reinforced cushion layer caused by vertical load, and considering the force balance effect of the vertical load of the reinforced cushion layer and the foundation reaction force, the average stress borne by the vertical load is obtained. : ;

[0140] The total tensile force of the stiffened body is calculated using the catenary theory. : .

[0141] S5, Calculate the total tensile force of the reinforced body caused by the slope thrust effect. :

[0142] In calculating the tensile force of the reinforced body in the reinforced cushion layer caused by slope thrust effect, the Coulomb active earth pressure coefficient is applied to determine the active earth pressure of the embankment slope. The calculation process is as follows:

[0143] Active earth pressure coefficient of embankment fill ;

[0144] Tensile force in reinforced body caused by slope thrust effect : .

[0145] S6, Calculate the tensile force of each layer of reinforcement in the reinforced cushion layer of the pile-net composite foundation:

[0146] In determining the tensile force of each layer of reinforcement in the pile-grid composite foundation reinforced cushion layer, the tensile forces of the reinforcement caused by vertical loads and those caused by embankment slope thrust are superimposed to obtain the tensile force of each layer of geogrid. The proportionality coefficient for the tensile force of the reinforcement caused by vertical loads is specified. By setting the value to 0.6, the actual tensile force of each layer of stiffener can be obtained. The specific calculation process is as follows.

[0147] First layer (bottom layer) reinforced structure:

[0148] Tensile distribution coefficient of the first layer of reinforced body caused by vertical load : ;

[0149] The distribution coefficient of tensile force in the first layer of reinforced body caused by slope thrust ;

[0150] Tensile force of the first layer of reinforcement : ;

[0151] Second layer (from bottom to top) reinforced structure:

[0152] The tensile force distribution coefficient of the second-layer reinforced body caused by vertical load ;

[0153] Distribution coefficient of tensile force in the second layer of reinforced body caused by slope thrust ;

[0154] Second layer of reinforcing tensile strength : ;

[0155] The third layer (from bottom to top) is reinforced:

[0156] Tensile distribution coefficient of the third-layer reinforced body caused by vertical load ;

[0157] Distribution coefficient of tensile force in the third layer of reinforced body caused by slope thrust ;

[0158] Third layer of reinforcing tensile strength : ;

[0159] Fourth layer (from bottom to top) reinforced structure:

[0160] Tensile force distribution coefficient of the fourth-layer reinforced body caused by vertical load : ;

[0161] Distribution coefficient of tensile force in the fourth layer of reinforced body caused by slope thrust ;

[0162] Fourth layer of reinforced tensile strength : .

[0163] The tensile stress values ​​of the reinforcement layers mentioned above were compared with the measured results of the tensile stress of the reinforcement layers in pile-supported reinforced roadbeds at a high-speed railway test base. Under the same pile layout conditions, the maximum tensile strain of the bottom layer reinforcement layer with multiple layers of geogrid was: The corresponding measured tensile force of the stiffened body is If calculated using a safety factor of 1.3, the tensile force of the design stiffener would be... It is the same as the result calculated by the method according to the present invention. The similarity indicates that the calculation method of the present invention is reasonable and can be used for tensile analysis calculation of multi-layered reinforced bodies.

[0164] The results of the tensile forces obtained for each layer of stiffeners , , and It can also be used to determine whether the strength parameters of the reinforced geomaterials selected in the design scheme can withstand the above-mentioned tensile forces;

[0165] If the calculated tensile strength of the reinforced body is greater than the design value of the tensile strength of the reinforced material, consider using a higher strength grade of reinforced soil geotextile or laying more layers of reinforced body;

[0166] If the calculated tensile strength of the reinforced body is much smaller than the design value of the tensile strength of the reinforced material, it is advisable to use a lower strength grade and more cost-effective reinforced soil geotextile material or reduce the number of layers of reinforced body to save costs.

[0167] If the calculated tensile strength of the reinforced body is slightly less than the design value of the tensile strength of the reinforced material, then the strength of the reinforced material and the number of layers in the reinforced cushion layer are reasonably selected.

Claims

1. A method for calculating the tensile force of a reinforcement body in a pile-net composite foundation reinforced cushion layer, characterized in that, The method comprises the following steps: S1, obtaining basic parameters of the pile-net composite foundation according to a design scheme of the pile-net composite foundation, including embankment parameters and reinforced foundation parameters; S2, calculating the average action stress σ of the soil between the piles at the pile top plane of the pile-net composite foundation according to the parameters of the fill embankment and the parameters of the reinforced foundation z0 : S3, calculating the average ground reaction force σ of the reinforced mat base of the pile-net composite foundation d ; S4, average stress of soil between piles σ z0 and S3, average reaction force of foundation σ d Calculate total tensile force of the reinforced body T caused by vertical load arc ; S5, calculate the total tensile force T of the reinforced body caused by the effect of the slope thrust slp ; S6, T obtained from S4 arc and T obtained from S5 slp Calculate the tensile force T of each layer of reinforcement in the pile-net composite foundation reinforced cushion gi The calculation formula is: T gi = a i T arc + b i T slp , Wherein: alpha i the first distribution coefficient of the i-th layer of the reinforcement, i is the layer number of the reinforcement in the reinforced cushion, 1≤i≤m, i=m is the top layer of the reinforcement; q is the proportional coefficient of the tensile force of the reinforcement caused by the vertical load, which is determined according to the actual situation; β i To calculate the second distribution coefficient of the i-th layer of the reinforced body, The sum of the first distribution coefficients of all the reinforced cushion layers is 1.0; the sum of the second distribution coefficients of all the reinforced cushion layers is also 1.0, and 0.5≤q≤0.

7.

2. The method according to claim 1, wherein the method is characterized in that: The parameters of the fill embankment in step S1 include: embankment height h, fill bulk density γ, and comprehensive internal friction angle of embankment fill Slope n of embankment and static load p of embankment top surface s ; The reinforcement foundation parameters include: pile spacing s, net distance between piles l, circular pile cap diameter d, equivalent square pile cap side length a, reinforced body grid porosity δ, and reinforced cushion bearing foundation soil internal friction angle and the total number of reinforced bodies m in the reinforced cushion.

3. The method according to claim 2, wherein the method is characterized in that: The average stress σ of the soil between the piles z0 = σ z01 + σ z02 , wherein σ z01 is the average stress caused by the static load of embankment fill, and σ z02 is the average stress caused by the dynamic stress of train distributed load.

4. The method according to claim 3, wherein the method is characterized by, The average stress σ caused by the embankment fill static load in step S2 z01 The calculation is performed using a spherical soil arch model, and the formula is as follows: In the formula: χ is an index parameter, χ = d(k p -1) / (λ2s); k p is the passive earth pressure coefficient of embankment fill λ1 and λ2 are the rugosity parameters, λ1 = 0.125(s-d) 2 , λ2 = 0.5(s 2 +2ds-d 2 ) / s 2 ; h g for the soil arch height, 5. The method according to claim 4, wherein the method is characterized in that: When calculating the average stress σ caused by the train distributed load dynamic stress in step S2 z02 First, the height of the embankment is judged. If the height of the embankment is greater than 3m, σ z02 =0; otherwise, the Boussinesq line load integration is used for calculation, and the formula is as follows: Wherein, p(x) is the train distribution load on the roadbed surface; z and R1 are the vertical distance and distance between the additional stress calculation point and the train distribution load micro-section, respectively; x0 and x1 are the start and end coordinates of the train distribution load on the roadbed surface; p(x), R1, z, x0 and x1 are determined according to the design scheme in S1.

6. The method according to claim 5, wherein the method is characterized in that: The ground average reaction force σ in step S3 d is calculated by the following equation: where k s is the composite stiffness of the pile-net composite foundation; ε is the controlled strain of the reinforcement, 4%≤ε≤6%.

7. The method according to claim 6, wherein the method is characterized in that: Total tensile force T of the reinforcement in step S4 arc This is calculated by the following formula: where σ g = σ z01 + σ z02 - σ d ; ε is the strain controlled by the reinforcement, 4% < ε < 6%.

8. The method according to claim 7, wherein the method is characterized in that: Total tensile force T of the reinforcement in step S5 slp This is calculated by the following formula: where K a is the active earth pressure coefficient of embankment fill.

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