Design method of inclined anchor foundation of transmission line

Abstract

The application discloses a design method of a transmission line inclined anchor foundation, establishes five basic assumptions, establishes a balance equation group of the inclined anchor foundation under the action of external load based on the static balance of external load and the foundation reaction force on the bottom surface of the pile cap according to the basic assumptions, rewrites the balance equation group into a deformation equation group about the horizontal displacement, vertical displacement and rotation angle of the pile cap in a space rectangular coordinate system according to the deformation coordination principle, degenerates the deformation equation group into a degenerate equation group for the design of the inclined anchor foundation, and calculates, and finally calculates the anchor rod internal force and the foundation reaction force under each working condition. The application breaks through the requirement that the anchor rod pile cap must be embedded in rock, expands the anchor rod foundation to the soil foundation, can effectively reduce the pile cap buried depth, avoids the formation of a deep foundation pit and a high and steep slope in the construction process, improves the technical and environmental protection advantages of the anchor rod foundation, and expands the application scene of the anchor rod foundation in the transmission line engineering.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power transmission line foundation, in particular to a design method of power transmission line inclined anchor foundation. BACKGROUND

[0002] With the development of electric power construction, the corridor of power transmission line is increasingly scarce, and the conditions of the location of the foundation of the power transmission tower are increasingly poor, especially in mountainous areas. The foundation of the power transmission tower will inevitably be located on the top of the mountain or the half-mountain, etc. The terrain in mountainous areas is steep, and the vegetation is lush. The construction of the access road for large mechanical equipment used for foundation construction has high cost and causes great damage to the ecological environment, which restricts the popularization and application of the mechanized construction mode.

[0003] Under the dual requirements of mechanized construction and water and environmental protection in mountainous areas, the anchor rod foundation constructed by light drilling machines has obvious advantages. However, the current anchor rod foundation design needs to embed the pile cap into the rock layer at least 0.5m according to the requirements of the “Design Code for Anchor Rod Foundation of Overhead Transmission Line” (DL / T 5544 2018). When the overburden layer is thick, the design depth of the pile cap increases accordingly. During the construction process, deep foundation pits and high and steep slopes are easily formed, which causes the risk of foundation pit collapse, slope instability and soil erosion, greatly weakening the technical and environmental protection advantages of the anchor rod foundation, and restricting the popularization and application of the anchor rod foundation in mountainous area power transmission line projects. SUMMARY

[0004] The present application provides a design method of power transmission line inclined anchor foundation, which has strong practicality, simple and accurate calculation process.

[0005] To achieve the above-mentioned purpose, the present application provides a design method of power transmission line inclined anchor foundation, comprising:

[0006] S1) Establish five basic assumptions

[0007] Basic assumption 1: the pile cap only has overall translation and rotation displacement under the action of external load, and does not produce deformation; basic assumption 2: there is an explicit relationship between the pile cap bottom surface ground reaction force and the foundation settlement; basic assumption 3: the relative position relationship between the anchor rod and the anchor rod does not change under the stress state of the foundation; basic assumption 4: the anchor rod is a two-force rod unit with both ends hinged; basic assumption 5: the passive earth pressure on the side surface of the foundation is ignored;

[0008] and a space rectangular coordinate system is established with the center of the pile cap bottom surface as the coordinate origin, the x-axis pointing to the tower center, the z-axis perpendicular to the ground downward, and the y-axis determined by the right-hand rule;

[0009] S2) Based on the basic assumption 1 and the basic assumption 5 in the step S1), and according to the static balance of the external load acting on the pile cap and the foundation reaction force at the bottom surface of the pile cap, the balance equation set of the inclined anchor foundation under the action of the external load is established;

[0010] S3) According to the deformation compatibility principle, the balance equation set is rewritten into the deformation equation set about the horizontal displacement, the vertical displacement and the rotation angle of the pile cap in the space rectangular coordinate system;

[0011] S4) For the design of the inclined anchor foundation, the deformation equation set is degenerated into the degenerated equation set, and the 、 、 ;

[0012] Wherein, is the vertical displacement of the pile cap at the coordinate origin, is the horizontal displacement of the pile cap, is the rotation angle of the pile cap, and the direction of the horizontal displacement of the pile cap is the same as the positive direction of the x axis of the space rectangular coordinate system, and the rotation angle of the pile cap is clockwise;

[0013] S5) According to the calculation of the anchor rod internal force and the foundation reaction force under each working condition. 、 、

[0014] Further, in the step S1), the horizontal load resultant force direction is made to be on the same straight line with the horizontal component of the inclined anchor rod internal force by rotating the pile cap; meanwhile, the anchor rods are uniformly distributed in the normal direction of the horizontal load resultant force.

[0015] Further, in the step S2), the balance equation set is as formula (1):

[0016] (1)

[0017] In formula (1), is the number of anchor rods in the x axis direction; is the number of anchor rods in the y axis direction; is the internal force of the anchor rod No. is the inclination angle of the anchor rod No. is the vertical force acting on the top of the foundation column, which is positive along the positive direction of the z axis; is the horizontal force acting on the top of the foundation column, which is positive along the positive direction of the x axis; is the self weight of the foundation and the overlying soil; is the bending moment acting on the center of the bottom surface of the pile cap; is the internal force of the anchor rod No. ​​​Root anchor and cap connection point Coordinates Width of the cap Length of the cap Foundation reaction force distribution function Friction coefficient of the cap and the foundation soil

[0018] Foundation soil base coefficient k according to basic assumption 2 s The relationship between the foundation reaction force distribution and the cap displacement is described as formula (2);

[0019] (2)

[0020] Cap vertical displacement function in the spatial rectangular coordinate system according to basic assumption 1

[0021]

[0022] Wherein, Vertical displacement of the cap at the origin of coordinates, positive along the positive direction of the z-axis; Cap rotation angle, positive clockwise.

[0023] Further, the deformation equation set in step S3) is as formula (3):

[0024]

[0025] Wherein, Horizontal displacement of the cap;

[0026] Based on basic assumption 3 and basic assumption 4:

[0027] , , Vertical reaction force coefficient of the anchor group, respectively, the sum of the vertical reaction force, the sum of the horizontal reaction force and the sum of the bending moment reaction force acting on the cap generated in the anchor group when the cap has a unit vertical displacement;

[0028] , , Horizontal reaction force coefficient of the anchor group, respectively, the sum of the vertical reaction force, the sum of the horizontal reaction force and the sum of the bending moment reaction force acting on the cap generated in the anchor group when the cap has a horizontal displacement;

[0029] , , Rotation angle reaction force coefficient of the anchor group, respectively, the sum of the vertical reaction force, the sum of the horizontal reaction force and the sum of the bending moment reaction force acting on the cap generated in the anchor group when the cap has a unit rotation angle;

[0030]

[0031] wherein, is the stiffness coefficient of the root anchor; is the stiffness coefficient of the root anchor;

[0032] When the anchor is in tension:

[0033]

[0034]

[0035] wherein, is the anchoring length of the anchor in the soil layer; is the elastic modulus of the rod body; is the elastic modulus of the grouting body; is the combined elastic modulus of the anchoring body; is the cross-sectional area of the rod body; is the cross-sectional area of the anchoring body; is the inclination angle of the anchor;

[0036] When the anchor is in compression, is obtained or taken from tests, simulations or theoretical analysis.

[0037] Further, for the inclined anchor foundation design in step S4), the deformation equation set is degenerated into a degenerated equation set, and , , the specific process is:

[0038] For the design of inclined anchor foundation under uplift working condition, it is first assumed that the pile cap is completely separated from the soil, i.e. the pile cap does not bear the reaction force of the foundation =0, and the stiffness coefficient of the anchor is the tensile stiffness coefficient of the anchor, and the deformation equation set formula (3) in step S3) is degenerated into formula (4):

[0039] (4)

[0040] If , the assumption that the pile cap is completely separated from the soil is established, and , , is calculated according to formula (4).

[0041] If , solve , , by formula (3) in step S2), specifically: for the working condition of bending moment load causing the pile cap to rotate clockwise, i.e. When, the lower limit of integration in formula (3) is... Change to For the condition where the foundation rotates counterclockwise, i.e. When, the upper limit of integration in formula (3) is... Change to .

[0042] Furthermore, in step S4), if an error occurs during the solution process... direction and The opposite direction, i.e. Then Set it to 0 and the friction coefficient between the foundation and the soil. As a new unknown, it is recalculated, specifically by rewriting formula (3) into formula (5) and solving it according to formula (5). , , ;

[0043]

[0044] Furthermore, in step S4), for the design of the inclined anchor foundation, the deformation equation set is degenerated into a degenerate equation set, and the calculation is performed. , , The specific process is as follows:

[0045] For the design of inclined anchor foundations under downward pressure conditions, it is first assumed that the entire cross-section of the bottom surface of the pile cap is under compression. = At this point, the stiffness coefficient of the anchor rod is the compressive stiffness coefficient of the anchor rod. Formula (3) in step S2) is rewritten as formula (6):

[0046] (6)

[0047] like The assumption that the entire cross-section of the bottom surface of the foundation is under compression holds true, and the calculation is performed according to formula (4). , , ;

[0048] like Then, the solution is obtained by formula (3) in step S2). , , For the condition where the bending moment load causes the foundation to rotate clockwise, i.e. When, the lower limit of integration in formula (3) is... Change to For the condition where the foundation rotates counterclockwise, i.e. When, the upper limit of integration in formula (3) is... Change to .

[0049] Furthermore, in step S4), if an error occurs during the solution process... direction and The opposite direction, i.e. , should be Set it to 0 and the friction coefficient between the foundation and the soil. As a new unknown, recalculate and rewrite formula (3) into formula (5), and solve according to formula (5). , , ;

[0050]

[0051] Further, step S5) is based on the obtained , , The specific formulas for calculating the internal forces of the anchor bolts and the ground reaction forces under various working conditions are as follows:

[0052] (7)

[0053] (2)

[0054]

[0055] in, For the first Internal forces in the anchor bolt.

[0056] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention breaks through the requirement that anchor foundations must be embedded in rock, extending the anchor foundation into the soil foundation, which can effectively reduce the burial depth of the foundation, avoid the formation of deep foundation pits and steep slopes during construction, improve the technical and environmental advantages of anchor foundations, expand the application scenarios of anchor foundations in power transmission line projects, and has significant engineering significance for environmental protection, soil and water conservation, adaptation to steep terrain conditions, and improvement of mechanization level and inherent safety; at the same time, the calculation method of the internal force of the anchor and the reaction force of the foundation under the downward and upward pulling conditions of the inclined anchor foundation of the power transmission line of this invention is simple, accurate and highly practical. Attached Figure Description

[0057] Figure 1 This is a plan view of the inclined anchor bolts for the foundation of a power transmission line.

[0058] Figure 2 This is a schematic diagram for calculating foundation reaction force.

[0059] Figure 3 A schematic diagram of the basic deformation and resistance distribution;

[0060] Figure 4 The calculation chart of group anchor counterforce coefficient under unit vertical displacement;

[0061] Figure 5 The calculation chart of group anchor counterforce coefficient under unit horizontal displacement;

[0062] Figure 6 The calculation chart of group anchor counterforce coefficient under unit rotation angle. DETAILED DESCRIPTION

[0063] The present application will be further described below in conjunction with the drawings and specific embodiments.

[0064] When the anchor rod foundation platform is not embedded in rock, the horizontal load and the base bending moment caused thereby will become the main control factor of the bearing capacity of the anchor rod foundation. The following design method of the inclined anchor foundation of the power transmission line can reduce the adverse effects of the horizontal force. The specific process is as follows:

[0065] S1) Establish five basic assumptions

[0066] Basic assumption 1: the platform only has overall translation and rotation displacement under the action of external load, and does not produce deformation; basic assumption 2: there is an explicit relationship between the foundation counterforce of the platform bottom surface and the foundation settlement; basic assumption 3: the anchor rod angle and the relative position relationship between the anchor rods do not change under the stress state of the foundation; basic assumption 4: the anchor rod is a two-force rod element with both ends hinged; basic assumption 5: the passive earth pressure on the side surface of the foundation is ignored;

[0067] and the horizontal force of the horizontal load resultant force is on the same straight line by rotating the platform; at the same time, the anchor rods are uniformly distributed in the normal direction of the horizontal load resultant force, at which time the anchor rod internal forces on the same row are equal, and the anchor rod group stress is converted from a space problem to a plane problem;

[0068] At the same time, as shown in Figure 3 , a space rectangular coordinate system is established with the center of the platform bottom surface as the coordinate origin, the x-axis pointing to the tower center, and the z-axis perpendicular to the ground downward, and the y-axis is determined by the right-hand rule.

[0069] S2) Based on the basic assumption 1 and the basic assumption 5 in step S1), and according to the static balance of the external load acting on the platform and the foundation counterforce of the platform bottom surface, the balance equation set of the inclined anchor foundation under the action of the external load is established;

[0070] (1)

[0071] In formula (1), is the number of anchor rods in the x-axis direction; is the number of anchor rods in the y-axis direction; is the number of anchor rods in the z-axis direction; The internal force of the root anchor, positive in tension and negative in compression; The vertical force acting on the top of the foundation column, positive in the positive direction of the z-axis; The inclination angle of the root anchor, positive in the clockwise direction and negative in the counterclockwise direction from the anchor axis to the z-axis; The vertical force acting on the top of the foundation column, positive in the positive direction of the z-axis; The horizontal force acting on the top of the foundation column, positive in the positive direction of the x-axis; The self-weight of the foundation and the overlying soil; The bending moment acting on the center of the bottom surface of the pile cap; The vertical force acting on the top of the foundation column, positive in the positive direction of the z-axis; The connection point of the root anchor and the pile cap The coordinate; The width of the pile cap; The length of the pile cap; The ground reaction force distribution function;

[0072] The friction coefficient between the pile cap and the soil, refer to the "Technical Code for Building Pile Foundation" (JGJ94-2008) for value;

[0073] The ground soil base coefficient k according to basic assumption 2 s The relationship between the ground reaction force distribution and the pile cap displacement is described as formula (2); k s It can be determined by indoor test or field plate load test. The test method can be found in "Code for Geotechnical Engineering Investigation of Urban Rail Transit" (GB 50307-2012). Appendix H of the specification provides empirical values of base coefficients for various commonly used rock and soil layers.

[0074] (2)

[0075] The vertical displacement function of the pile cap in the spatial rectangular coordinate system according to basic assumption 1;

[0076]

[0077] Wherein, The vertical displacement of the pile cap at the origin of the coordinate system, positive in the positive direction of the z-axis; The rotation angle of the pile cap, positive in the clockwise direction.

[0078] According to the deformation compatibility principle, formula (1) is rewritten into a deformation equation group about the horizontal displacement, vertical displacement and rotation angle of the pile cap in the coordinate system:

[0079]

[0080] Wherein, The horizontal displacement of the pile cap;

[0081] Based on basic assumption 3 and basic assumption 4:

[0082] 、 、 is the vertical force coefficient of the group anchor, respectively, the sum of the vertical force, the sum of the horizontal force and the sum of the bending moment force acting on the pile cap generated by the unit vertical displacement of the pile cap in the anchor group;

[0083] 、 、 is the horizontal force coefficient of the group anchor, respectively, the sum of the vertical force, the sum of the horizontal force and the sum of the bending moment force acting on the pile cap generated by the horizontal displacement of the pile cap in the anchor group;

[0084] 、 、 is the rotation angle force coefficient of the group anchor, respectively, the sum of the vertical force, the sum of the horizontal force and the sum of the bending moment force acting on the pile cap generated by the unit rotation angle of the pile cap in the anchor group;

[0085] Based on Figure 4 、 5 , 6, the relationship between the internal force of the anchor rod and its deformation is described by Hooke's law and force balance:

[0086]

[0087] wherein, is the stiffness coefficient of the first anchor rod;

[0088] As shown in Figure 1 、 Figure 2 , all external loads equivalent to the center of the pile cap bottom are counted, and the anchor rod stiffness coefficient is calculated. According to the Technical Code for Building Slope Engineering (GB 50330-2013), the calculation method of the full-length bonded soil layer anchor rod uplift stiffness coefficient when lacking test data can be derived.

[0089] When the anchor rod is in tension:

[0090]

[0091]

[0092] wherein, is the anchoring length of the anchor rod in the soil layer; is the elastic modulus of the rod body; is the elastic modulus of the grouting body; is the combined elastic modulus of the anchoring body; is the cross-sectional area of the rod body; is the cross-sectional area of the anchoring body; is the anchoring rod inclination angle;

[0093] when the anchoring rod is in compression, is obtained or taken from tests, simulations, or theoretical analysis.

[0094] S3) For the design of the inclined anchor foundation under the uplift working condition, it is first assumed that the pile cap is completely separated from the soil, i.e., the pile cap does not bear the foundation reaction force = 0, and the stiffness coefficient of the anchoring rod is the uplift stiffness coefficient of the anchoring rod, and formula (3) in step S2) is degenerated into formula (4):

[0095] (4)

[0096] If , the assumption that the pile cap is completely separated from the soil is established, and , , are calculated according to formula (4).

[0097] If , is solved by formula (3) in step S2) , , , specifically: for the working condition in which the bending moment load causes the pile cap to rotate clockwise, i.e. , the lower limit of the integral in formula (3) is changed to ; for the working condition in which the pile cap rotates counterclockwise, i.e. , the upper limit of the integral in formula (3) is changed to .

[0098] In addition, if the direction is opposite to the direction, i.e. , should be set to 0 and the friction coefficient between the pile cap and the foundation soil is taken as a new unknown quantity to be recalculated, and formula (3) is rewritten as formula (5), and , , , are solved according to formula (5).

[0099]

[0100] or for the design of the inclined anchor foundation under the downward pressure working condition, it is first assumed that the entire cross-section of the pile cap bottom surface is under compression, i.e. = 0. At this time, the stiffness coefficient of the anchor rod is the compression stiffness coefficient of the anchor rod, and the formula (3) in step S2) is rewritten as formula (6):

[0101] (6)

[0102] If , the assumption that the entire cross section of the pile cap bottom surface is under compression is valid, and , , are calculated according to formula (4);

[0103] If , is solved by formula (3) in step S2) , , ; for the working condition in which the bending moment load causes the pile cap to rotate clockwise, i.e. , the lower limit of the integral in formula (3) is changed to ; for the working condition in which the pile cap rotates counterclockwise, i.e. , the upper limit of the integral in formula (3) is changed to ;

[0104] In addition, if the direction is opposite to the direction, i.e. , set to 0 and the friction coefficient between the pile cap and the foundation soil as a new unknown quantity to recalculate, rewrite formula (3) as formula (5), and solve , , according to formula (5);

[0105]

[0106] S4) Calculate the anchor rod internal force and the ground reaction force under each working condition according to , , obtained in step S3);

[0107] (7)

[0108] (2)

[0109]

[0110] wherein is the internal force of the i-th anchor rod.

[0111] ​The optimization method of the application is further described below in combination with specific embodiments

[0112] 1) Determine the basic information of the bearing platform, anchor rod and foundation soil and the working load

[0113] a) Determine the geometric size of the bearing platform and anchor rod, the material mechanics parameters of the anchor rod and the arrangement scheme

[0114] Determine the width of the bearing platform = 2.6 m, the length = 2.6 m, the height = 1.3 m; the height of the short column = 1 m, 0.2 m above the ground, the short column is arranged with an eccentricity of 0.35 m to reduce the bending moment of the bearing platform bottom surface under the horizontal load.

[0115] Determine the elastic modulus of the anchor rod = 200 GPa, the diameter of the anchor rod = 0.036 m, the elastic modulus of the grouting body = 30 GPa, the diameter of the anchor rod = 0.15 m, the calculation length of the anchor rod = 8.5 m. The stiffness coefficient of the anchor rod is 2.48 kN / m calculated according to the formula under tension , and 0 under compression for the sake of being conservative.

[0116] Determine the anchor rod arrangement scheme as 4 4 is uniformly distributed, that is, = = 4, the center distance of the anchor rod is 0.65 m, and the inclination angles of the anchor rods from left to right in the figure are -20°, -20°, 20° and 20°.

[0117] The weight of the foundation and the overlying soil is 20 kN / m³, the base coefficient of the foundation soil = 5000 kN / m³, and the friction coefficient = 0.3.

[0118] b) Determine the working load

[0119] Determine the axial load of the pulling working condition 1000 kN, the direction is the negative direction of the z-axis; the horizontal load of the pulling working condition 169.71 kN, the direction is the negative direction of the x-axis; the pulling bending moment acting on the center of the bearing platform bottom surface 40.32 kN·m, the direction is the positive direction of the y-axis, which causes the bearing platform to rotate counterclockwise. The axial load of the pressing working condition 1350 kN, the direction is the positive direction of the z-axis; the horizontal load of the pressing working condition 286.38 kN, direction is x axis positive direction; the down pressure bending moment acting on the bottom center of the bearing platform 186.17 kN.m, direction is y axis negative direction, making the bearing platform rotate clockwise. The foundation and the overburden weight 283.92 kN.

[0120] 2) Calculate the displacement of the bearing platform

[0121] a) Calculate the anchor internal force and the ground soil reaction force under the uplift working condition

[0122] First, calculate the group anchor reaction force coefficient according to the tensile stiffness of all anchors, and use the corresponding formula in step S2) to obtain 、 、 、 、 、 Assuming that the bearing platform is completely separated from the soil, equation set (5) is used to obtain 、 、 Since , the assumption that the bearing platform is completely separated from the soil is contradictory.

[0123] For the time being , it is judged that the bearing platform rotates counterclockwise. Change the upper limit of the integral of equation set (3) to , and solve to obtain 、 、 , which is contradictory to the premise of counterclockwise rotation of the bearing platform. Change the lower limit of the integral in equation set (3) to , and solve to obtain 、 、 , which is consistent with the premise of clockwise rotation of the bearing platform, and is in the same direction as .

[0124] Calculate the internal force of each anchor using formula (6) to obtain kN、 kN、 kN、 kN. Among them , indicating that the pressure generated by the anchor rod is contradictory to the premise of using tensile stiffness. The stiffness of the second row of anchors is modified to compressive stiffness (0) and the above calculation is repeated. Finally, the displacement of the bearing platform is obtained as 、 、 . The internal force of the anchor rod is 45.98 kN、 0 kN、 132.05 kN、 26.45 kN. The maximum ground reaction force is calculated by using equation (7) kPa, the minimum ground reaction force is .

[0125] b) Calculate the anchor internal force and ground reaction force in the compression condition

[0126] Here only the solving process and final results are described, and the error results in the trial process are not described. First, the group anchor reaction force coefficient is calculated according to the assumption that all anchors have uplift stiffness, and the bottom surface of the pile cap is assumed to be fully compressed, and the equation set (3) is solved, and it is found that is inconsistent with the assumption, and the upper limit or lower limit of the integral in the equation is judged according to the sign of , and the pile cap displacement is recalculated. The anchor internal force is calculated by using formula (6), and the stiffness is corrected according to whether the anchor is in tension or not, and finally the correct pile cap displacement is , , , the static friction coefficient . The anchor internal force is 0. The maximum ground reaction force is kPa, the minimum ground reaction force is kPa.

[0127] The calculation results of the two conditions are shown in the following table.

[0128]

[0129] The calculation diagram used in the above description is only for convenience of description, and the embodiments of the present application are not limited thereto. The ground soil base coefficient used in the calculation process of the present application is only a kind of explicit relationship selected for the assumption 2, and does not mean that the design method of the present application is only applicable to the case that the ground soil base coefficient can be used. The present application has deduced the design method considering the compression stiffness of the anchor, and at the same time, the calculation method without considering the compression stiffness coefficient of the anchor is given in the specific embodiment, which does not mean that the design method of the present application is only applicable to the case without considering the compression stiffness of the anchor. Any change, modification, substitution, combination and simplification made without departing from the spirit and principle of the present application shall be equivalent replacement, which is included in the protection scope of the present application.

Claims

1. A method of designing a foundation for a transmission line guy anchor, the method comprising: Comprising ​ S1 establishes five basic assumptions Basic assumption 1: the bearing platform only has overall translation and rotation displacement under the action of external load, and does not produce deformation; basic assumption 2: there is an explicit relationship between the bearing platform bottom ground reaction force and foundation settlement; basic assumption 3: the anchor rod included angle and the relative position relationship between the anchor rods do not change under the stress state of the inclined anchor foundation; basic assumption 4: the anchor rod is a two-force rod unit with both ends hinged; basic assumption 5: the passive soil pressure on the side surface of the foundation is ignored; S2 establishes a space rectangular coordinate system with the center of the bearing platform bottom surface as the coordinate origin, the x-axis pointing to the tower center, the z-axis perpendicular to the ground downward, and the y-axis determined by the right-hand rule; S2 establishes a balance equation set of the inclined anchor foundation under the action of external load based on the basic assumption 1 and the basic assumption 5 in step S1, and according to the static balance of the external load acting on the bearing platform and the bearing platform bottom ground reaction force; S3 rewrites the balance equation set into a deformation equation set about the horizontal displacement, vertical displacement and rotation angle of the bearing platform in the space rectangular coordinate system according to the deformation compatibility principle; S4 For the inclined anchor foundation design, the deformation equation set is degenerated into a degenerated equation set, and the , , ; wherein, is the vertical displacement of the pile cap at the coordinate origin, is the horizontal displacement of the pile cap, is the pile cap rotation angle, the horizontal displacement direction of the pile cap is positive in the same direction as the positive direction of the x-axis of the spatial rectangular coordinate system, and the pile cap rotation angle is positive in the clockwise direction. S5 according to , , calculate the anchor rod internal force and the foundation reaction force under each working condition; The balance equation set in step S2 is as formula (1): （1）； In formula (1), is the number of anchor rods in the x-axis direction; is the number of anchor rods in the y-axis direction; is the internal force of the i-th anchor rod, and is positive for tension and negative for compression; is the internal force of the i-th anchor rod, and is positive for tension and negative for compression; is the inclination angle of the i-th anchor rod, from the anchor rod axis to the z-axis direction, positive clockwise and negative counterclockwise; is the vertical force acting on the top of the foundation column, positive along the positive direction of the z-axis; is the horizontal force acting on the top of the foundation column, positive along the positive direction of the x-axis; is the self-weight of the foundation and overlying soil; is the bending moment acting on the center of the bottom surface of the pile cap; is the bending moment acting on the center of the bottom surface of the pile cap; is the connection point of the i-th anchor rod and the pile cap coordinate; is the width of the pile cap; is the length of the pile cap; is the length of the pile cap; is the ground reaction force distribution function; is the friction coefficient between the pile cap and the ground soil; For the basic assumption 2 to adopt the ground base bed coefficient k s The relationship between the ground reaction force distribution and the pile cap displacement is described as formula (2); （2）； is the vertical displacement function of the pile cap in the spatial orthogonal coordinate system according to the basic assumption 1; ； wherein, is the vertical displacement of the pile cap at the coordinate origin, positive along the positive z-axis; is the rotation angle of the pile cap, positive for clockwise rotation.

2. The method of designing a foundation for a power transmission line according to claim 1, wherein: In step S1, the horizontal load resultant force and the horizontal component of the internal force of the inclined anchor rod are also made to be on the same straight line by rotating the bearing platform; at the same time, the anchor rods are uniformly distributed in the normal direction of the horizontal load resultant force.

3. The method of designing a foundation for a power transmission line according to claim 1, wherein: The deformation equation set in step S3 is as formula (3): ； wherein, is the horizontal displacement of the pile cap; Based on the basic assumption 3 and the basic assumption 4: , , is the vertical reaction force coefficient of the group anchor, respectively, the sum of the vertical reaction force, the sum of the horizontal reaction force and the sum of the bending moment reaction force acting on the pile cap generated by the unit vertical displacement of the pile cap in the anchor group; , , are the horizontal reaction force coefficients of the group anchor, respectively, the sum of the vertical reaction force, the sum of the horizontal reaction force and the sum of the bending moment reaction force acting on the pile cap generated by the horizontal displacement of the pile cap in the anchor group; , , are the group anchor corner reaction force coefficients, respectively, the sum of the vertical reaction force, the sum of the horizontal reaction force and the sum of the bending moment reaction force acting on the pile cap generated in the anchor group when the pile cap occurs a unit corner. ； wherein is the first the stiffness coefficient of the root anchor When the anchor rod is in tension: ； ； wherein, is the anchoring length of the anchor rod in the soil layer; is the elastic modulus of the rod body; is the elastic modulus of the grouting body; is the combined elastic modulus of the anchoring body; is the cross-sectional area of the rod body; is the cross-sectional area of the anchoring body; is the inclination angle of the anchor rod; When the anchor rod is in a compression state, Obtained or taken from tests, simulations or theoretical analyses.

4. The method of designing a foundation for a power transmission line according to claim 3, wherein: In the step S4, for the design of the inclined anchor foundation, the deformation equation set is degenerated into a degenerated equation set, and the following is calculated , , The specific process is as follows: For the design of the inclined anchor foundation under the uplift condition, it is firstly assumed that the pile cap is completely separated from the soil, i.e. the pile cap does not bear the reaction force of the foundation =0, and the stiffness coefficient of the anchor rod is the tensile stiffness coefficient of the anchor rod, and the deformation equation set formula (3) in step S3 is degenerated into formula (4): （4）； If , the assumption that the pile cap is completely separated from the soil is valid, and the pile cap is calculated according to formula (4) , , ; If , then the integral lower limit in formula (3) is changed to in step S3. , specifically: for the working condition of bending moment load causing the pile cap to rotate clockwise, i.e. , the integral lower limit in formula (3) is changed to ; For the condition that the bearing platform rotates counterclockwise, i.e. , the upper limit of the integral in formula (3) is changed to . .

5. The method for designing a foundation for a power transmission line according to claim 4, characterized in that: In the step S4, if the following condition occurs in the solving process the direction is opposite to the direction, i.e. , the value of is set to 0 and the friction coefficient between the pile cap and the ground is recalculated as a new unknown quantity, specifically, formula (3) is rewritten as formula (5), and , , is solved according to formula (5). 。 6. The method of designing a foundation for a power transmission line according to claim 3, wherein: In the step S4, for the design of the inclined anchor foundation, the deformation equation set is degenerated into a degenerated equation set, and the following is calculated , , The specific process is as follows: For the design of the inclined anchor foundation under the down pressure condition, it is firstly assumed that the full section of the bottom surface of the pile cap is under pressure, i.e. = At this time, the stiffness coefficient of the anchor rod is the compression stiffness coefficient of the anchor rod, and the formula (3) in step S3 is rewritten as formula (6): （6）； If , the assumption of the full cross-section of the bottom surface of the pile cap being under compression is valid, and the formula (6) is used for calculation , , ; If , then the integral lower limit in formula (3) is changed to , ; for the case that the bending moment load makes the pile cap rotate clockwise, i.e. , the integral lower limit in formula (3) is changed to ; For the working condition that the bearing platform rotates counterclockwise, i.e. , the upper limit of the integral in formula (3) is changed to . .

7. The method for designing a foundation for a power transmission line according to claim 6, wherein: In the step S4, if the following condition occurs in the solving process the direction is opposite to the direction, i.e. , the value of is set to 0 and the friction coefficient between the pile cap and the ground soil is taken as a new unknown quantity to be recalculated, the formula (3) is rewritten as formula (5), and , , are solved according to the formula (5). 。 8. The method of designing a foundation for a power transmission line according to claim 1, wherein: The step S5 is based on the obtained , , The specific formula for calculating the anchor rod internal force and the foundation reaction force under each working condition is as follows: （7）； （2）； ； wherein is the first the internal force of the root anchor, is the first the stiffness coefficient of the root anchor.

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