Method for calculating uplift force of stiffened plate type foundation of power transmission line

Abstract

The invention relates to the technical field of electric power, and discloses a power transmission line stiffened plate type foundation uplift force calculation method, which adopts a friction reinforcement principle and a soil weight method, and combines a soil mechanics theory and an elastic mechanics theory to calculate the uplift force of a stiffened plate type foundation of a power transmission line. And calculating the upward pulling force of the plate type foundation under the combined action of the rib materials and the backfill soil. The invention discloses a method for calculating the uplift force of a stiffened plate type foundation of a power transmission line, and solves the problem that there is no suitable method for calculating the uplift force of the stiffened plate type foundation in the prior art.

Description

Technical Field

[0001] The invention relates to the field of electric power technology, in particular to a method for calculating the pullout force on a reinforced plate foundation of a power transmission line. Background Art

[0002] Transmission lines often pass through desert areas. Due to the nature of loose sand in the desert, slab foundation is a commonly used foundation type. Reinforced slab foundation has been tried in transmission lines. Tests have shown that reinforced slab foundation can significantly improve the pull-out bearing capacity of the slab foundation and has a better wind-proof and sand-fixing effect. However, there is no suitable method for calculating the pull-out force on the reinforced slab foundation. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a method for calculating the pullout force on a reinforced plate foundation of a power transmission line, thereby solving the problems existing in the prior art such as the lack of a suitable method for calculating the pullout force on a reinforced plate foundation.

[0004] The technical solution adopted by the present invention to solve the above problems is:

[0005] A method for calculating the pullout force on a reinforced slab foundation of a power transmission line adopts the friction reinforcement principle and the soil weight method, combines soil mechanics theory and elastic mechanics theory, and calculates the pullout force of the slab foundation under the combined action of reinforcement and backfill soil.

[0006] As a preferred technical solution, if dF>dT, the reinforcement remains stable; wherein dF represents the total friction force generated by the soil and the reinforcement on the plate foundation, and dT represents the tension exerted on the reinforcement.

[0007] As a preferred technical solution, dT=T1-T2, dF=2σfbdl; wherein dT represents the tension caused in the reinforcement of the micro-unit segment, T1 represents the force on the left section of the reinforcement, T2 represents the force on the right section of the reinforcement, σ represents the normal stress pressing the reinforcement, f represents the friction coefficient between the reinforcement and the soil, b represents the width of the reinforcement strip, and dl represents the length of the reinforcement anchoring section.

[0008] As a preferred technical solution, when h>h c When h≤h c When the soil is damaged, it is in the shape of a cone; h represents the burial depth of the plate foundation, h c Indicates the critical burial depth of the slab foundation.

[0009] As a preferred technical solution, T U =γ E (G U1 +T U2 +T U3) / K1+G / K2; where T U Indicates the standard value of the pull-out bearing capacity of the plate foundation, G U1 represents the deadweight of the soil within the uplift influence range, T U2 It represents the pull-out resistance of the geogrid laid on the surface of the slab foundation, T U3 It represents the pull-out resistance of the geogrid laid between the ground surface and the slab foundation surface, G represents the deadweight of the slab foundation, K1 represents the design safety factor related to the foundation resistance, K2 represents the design safety factor related to the deadweight of the foundation, γ E Represents the horizontal force influence coefficient.

[0010] As a preferred technical solution, when h>h c hour,

[0011]

[0012] Where γ represents the weighted degree of the soil above the bottom of the slab foundation, h c It represents the critical buried depth of the slab foundation, h represents the buried depth of the slab foundation, B represents the width of the slab foundation, α represents the upper pull-up angle, and V0 represents the volume of the slab foundation within the buried depth h.

[0013] As a preferred technical solution, when h≤h c hour,

[0014]

[0015] Where γ represents the weighted degree of the soil above the bottom of the slab foundation, h c It represents the critical buried depth of the slab foundation, h represents the buried depth of the slab foundation, B represents the width of the slab foundation, α represents the upper pull-up angle, and V0 represents the volume of the slab foundation within the buried depth h.

[0016] As a preferred technical solution, T U2 =(c1+γdtanφ1)A1(sinθ+cosθtanφ); where c1 represents the interfacial cohesion between reinforced aeolian sand and geogrid, γ represents the weighted measure of the soil above the bottom of the slab foundation, φ1 represents the interfacial friction angle between aeolian sand and geogrid, A1 represents the reinforcement area outside the rupture surface of the first layer of reinforcement, θ represents the geogrid pull-out angle, d represents the buried depth of the first layer of reinforcement, and φ represents the friction angle of reinforced aeolian sand.

[0017] As a preferred technical solution, T U3=(c1+γd1 tanφ1)A2(sinθ+cosθtanφ); where c1 represents the interfacial cohesion between reinforced aeolian sand and geogrid, γ represents the weighted measure of the soil above the bottom of the slab foundation, φ1 represents the interfacial friction angle between reinforced aeolian sand and geogrid, A2 represents the area of ​​the reinforcement outside the rupture surface of the second layer of reinforcement, θ represents the pull-out angle of the geogrid, and d1 represents the buried depth of the second layer of reinforcement.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention can consider the contribution of reinforcement to the uplift bearing capacity of the square bottom plate foundation, and propose a method for calculating the uplift bearing capacity of the reinforced soil composite foundation, which can give full play to the joint effect of reinforcement and soil, improve the uplift bearing capacity of the reinforced plate foundation, and has high economic value;

[0020] (2) It can effectively reduce the size of the slab foundation, save materials, and improve the economic benefits of the project.

[0021] (3) It can reduce the scope of excavation disturbance, which is beneficial to environmental protection and at the same time gives full play to the wind-proof and sand-fixing effects of the reinforced materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the failure model of reinforced soil composite;

[0023] Figure 2 for Figure 1 One of the partial enlarged pictures;

[0024] Figure 3 for Figure 1 The second partial enlarged image. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0026] Example 1

[0027] like Figures 1 to 3 As shown, the present invention adopts the friction reinforcement principle, combines the classical soil mechanics theory and the elastic mechanics theory, and proposes a method for calculating the pullout force on the reinforced soil slab foundation, taking into account the pullout force of the slab foundation under the combined action of the reinforcement material and the backfill soil.

[0028] 1) Friction reinforcement principle

[0029] The failure model of reinforced soil composite is as follows Figure 1 shown.

[0030] The length of the reinforcement anchorage section is dl, the force on the left section of the reinforcement is T1, the force on the right section of the reinforcement is T2, the normal stress pressing the reinforcement is σ, and the weight of the reinforcement strip and the weight of the micro-unit soil are ignored. Let the friction coefficient between the reinforcement and the soil be f, and let b be the width of the reinforcement strip. The tension caused in the reinforcement of the micro-unit is dT.

[0031] dT=T1-T2 (1)

[0032] Assuming dF is the total friction force generated by the soil and the reinforcement in this microelement segment, we have:

[0033] dF=2σfbdl (2)

[0034] dT=T1-T2, dF=2σfbdl; T1 represents the force on the left section of the reinforcement, T2 represents the force on the right section of the reinforcement, σ represents the normal stress pressing the reinforcement, f represents the friction coefficient between the reinforcement and the soil, b represents the width of the reinforcement strip, dl represents the length of the reinforcement anchorage section, dF represents the total friction force generated by the soil and the reinforcement on the slab foundation, and dT represents the tension exerted on the reinforcement.

[0035] According to the force analysis of the micro-unit, if dF>dT, there will be no mutual displacement between the reinforcement and the soil, and the reinforcement will remain stable, that is, the reinforcement will not be pulled out, indicating that the slab foundation under the joint action of reinforcement and soil can remain stable; in other words, the horizontal force of the soil is overcome by the friction between the reinforcement and the soil, and the micro-unit remains stable. Otherwise, it cannot remain stable.

[0036] 2) Calculation of ultimate pull-out bearing capacity

[0037] When h>h c =1.5B, where h is the depth of the foundation slab, and B is the width of the slab; the failure shape of the soil is a combination of a cone and a column, and the burial depth h c The shape of the damaged soil below is a column, and the shape at the base is approximately square. c The connection between the inverted cone and the cone is approximately circular; the buried depth h c The above soil failure form is approximately a frustum. c When the soil is damaged, the failure shape is a cone. Figure 1 shown.

[0038] The pull-out capacity of reinforced wind-blown sand should be equal to the vertical projection of the self-weight of the destroyed soil, the shear resistance of the side surface, and the pull-out capacity of each layer of geogrid. Under the ultimate pull-out displacement of the foundation slab, the total friction generated by the interface between the geogrid and the soil has an angle θ with the horizontal plane. The decomposition of the total friction in the vertical direction directly constitutes a part of the pull-out resistance, and the decomposition in the horizontal direction forms a horizontal constraint on the soil, increasing the shear resistance of the soil. Based on this integration, the following theoretical calculation formula is obtained:

[0039] T U =γ E (G U1 +T U2 +T U3 ) / K1+G / K2; where T U Indicates the standard value of the pull-out bearing capacity of the plate foundation, G U1 represents the deadweight of the soil within the uplift influence range, T U2 It represents the pull-out resistance of the geogrid laid on the surface of the slab foundation, T U3 It represents the pull-out resistance of the geogrid laid between the ground surface and the slab foundation surface, G represents the deadweight of the slab foundation, K1 represents the design safety factor related to the foundation resistance, K2 represents the design safety factor related to the deadweight of the foundation, γ E Represents the horizontal force influence coefficient.

[0040] 1) When h>h c hour,

[0041] 2) When h≤h c hour,

[0042] 3) Where γ represents the weighted mass of the soil above the bottom of the slab foundation (kN / m 3 ), h c Indicates the critical buried depth of the plate foundation (m), usually h c =1.5B, h represents the burial depth of the slab foundation (m), B represents the width of the slab foundation (m), α represents the uplift angle (°), V0 represents the volume of the slab foundation within the burial depth h (m 3 ).

[0043] T U2 =(c1+γdtanφ1)A1(sinθ+cosθtanφ); where c1 represents the interfacial cohesion between reinforced aeolian sand and geogrid (kPa), and γ represents the weighted mass of the soil above the bottom of the slab foundation (kN / m 3 ), φ1 represents the interface friction angle between aeolian sand and geogrid (°), A1 represents the reinforcement area outside the rupture surface of the first reinforcement layer (m 2), θ represents the geogrid pull-up angle (°), d represents the buried depth of the first layer of reinforcement (m), and φ represents the soil friction angle (°).

[0044] T U3 =(c1+γd1tanφ1)A2(sinθ+cosθtanφ); where c1 represents the interfacial cohesion between reinforced aeolian sand and geogrid (kPa), and γ represents the weighted mass of the soil above the bottom of the slab foundation (kN / m 3 ), φ1 represents the interface friction angle between reinforced aeolian sand and geogrid (°), A2 represents the reinforcement area outside the rupture surface of the second reinforcement layer (m 2 ), θ represents the geogrid pull-up angle (°), and d1 represents the buried depth of the second layer of reinforcement (m).

[0045] As described above, the present invention can be preferably implemented.

[0046] All features disclosed in all embodiments in this specification, or steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for calculating the pullout force on a reinforced plate foundation of a transmission line, characterized in that: The friction reinforcement principle and soil weight method are used, combined with soil mechanics theory and elastic mechanics theory, to calculate the uplift force of the slab foundation under the combined action of the reinforcement and backfill soil.

2. A method for calculating the pullout force on a reinforced plate foundation of a power transmission line according to claim 1, characterized in that: If dF>dT, the reinforcement remains stable; where dF represents the total friction force generated between the soil and the reinforcement on the slab foundation, and dT represents the tension exerted on the reinforcement.

3. The method for calculating the pullout force on the reinforced plate foundation of a power transmission line according to claim 2, characterized in that: dT=T1-T2, dF=2σfbdl; where dT represents the tension caused in the reinforcement of the micro-unit segment, T1 represents the force on the left section of the reinforcement, T2 represents the force on the right section of the reinforcement, σ represents the normal stress pressing the reinforcement, f represents the friction coefficient between the reinforcement and the soil, b represents the width of the reinforcement strip, and dl represents the length of the reinforcement anchorage section.

4. A method for calculating the pullout force on a reinforced plate foundation of a power transmission line according to claim 3, characterized in that: When h>h c When h≤h c When the soil is damaged, it is in the shape of a cone; where h represents the burial depth of the plate foundation, h c Indicates the critical burial depth of the slab foundation.

5. A method for calculating the pullout force on a reinforced plate foundation of a power transmission line according to claim 4, characterized in that: T U =γ E (G U1 +T U2 +T U3 ) / K1+G / K2; where T U Indicates the standard value of the pull-out bearing capacity of the plate foundation, G U1 represents the deadweight of the soil within the uplift influence range, T U2 It represents the pull-out resistance of the geogrid laid on the surface of the slab foundation, T U3 It represents the pull-out resistance of the geogrid laid between the ground surface and the slab foundation surface, G represents the deadweight of the slab foundation, K1 represents the design safety factor related to the foundation resistance, K2 represents the design safety factor related to the deadweight of the foundation, γ E Represents the horizontal force influence coefficient.

6. A method for calculating the pullout force on a reinforced plate foundation of a power transmission line according to claim 5, characterized in that: When h>h c hour, Where γ represents the weighted degree of the soil above the bottom of the slab foundation, h c It represents the critical buried depth of the slab foundation, h represents the buried depth of the slab foundation, B represents the width of the slab foundation, α represents the upper pull-up angle, and V0 represents the volume of the slab foundation within the buried depth h.

7. A method for calculating the pullout force on a reinforced plate foundation of a power transmission line according to claim 5, characterized in that: When h≤h c hour, Where γ represents the weighted degree of the soil above the bottom of the slab foundation, h c It represents the critical buried depth of the slab foundation, h represents the buried depth of the slab foundation, B represents the width of the slab foundation, α represents the upper pull-up angle, and V0 represents the volume of the slab foundation within the buried depth h.

8. The method for calculating the pullout force on the reinforced plate foundation of a power transmission line according to claim 5, characterized in that: T U2 =(c1+γdtanφ1)A1(sinθ+cosθtanφ); where c1 represents the interfacial cohesion between reinforced aeolian sand and geogrid, γ represents the weighted measure of the soil above the bottom of the slab foundation, φ1 represents the interfacial friction angle between aeolian sand and geogrid, A1 represents the reinforcement area outside the rupture surface of the first layer of reinforcement, θ represents the geogrid pull-out angle, d represents the buried depth of the first layer of reinforcement, and φ represents the friction angle of reinforced aeolian sand.

9. The method for calculating the pullout force on the reinforced plate foundation of a power transmission line according to claim 5, characterized in that: T U3 =(c1+γd1 tanφ1)A2(sinθ+cosθtanφ); where c1 represents the interfacial cohesion between reinforced aeolian sand and geogrid, γ represents the weighted measure of the soil above the bottom of the slab foundation, φ1 represents the interfacial friction angle between reinforced aeolian sand and geogrid, A2 represents the area of ​​the reinforcement outside the rupture surface of the second layer of reinforcement, θ represents the pull-out angle of the geogrid, and d1 represents the buried depth of the second layer of reinforcement.

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