Power transmission tower foundation design method considering tower footing joint effect

Abstract

The invention provides a power transmission tower foundation design method considering a tower footing joint effect, which comprises the following steps: establishing an iron tower overall model in simulation software, respectively applying horizontal and vertical loads to the tower foot of an iron tower, gradually increasing the loads from small to large to obtain a load-displacement curve, and determining the rigidity of the tower foot in the horizontal and vertical directions according to the load-displacement curve; based on a stiffness equivalent principle, establishing an arched beam, and adjusting the sectional area and arch height parameters of the arched beam to enable the stiffness in two directions of an arch foot to be equal to the stiffness in the horizontal direction and the vertical direction of the tower foot of the iron tower; four foundation models of the iron tower are established, and the adjacent foundations are connected through the arched beams; geological parameters are input, meanwhile, tower footing acting force obtained through iron tower calculation is applied to the top end of the foundation for overall foundation analysis, and the foundation size meeting the bearing capacity and deformation requirements is obtained. According to the method, basic modeling is simplified, the calculation efficiency is greatly improved, and good economic benefits and social benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of transmission tower design, and in particular relates to a transmission tower foundation design method taking into account the combined effect of the tower and base. Background Art

[0002] With the development of the power industry, more and more overhead transmission lines have been put into operation. While transmission line failures are common, they are rarely caused by insufficient foundation bearing capacity. This is due to conservative design methods for overhead transmission line foundations. A major reason for this is that tower foundations are calculated as independent foundations, without considering the contribution of tower stiffness to the coordinated foundation forces. In transmission line engineering design, tower foundations are calculated separately based on the tower base forces extracted after tower calculations. However, because the towers are fixed to four foundations, there is essentially a steel frame between the foundations to coordinate their deformation. Therefore, there must be a certain coordination effect between the forces and displacements of the foundations. However, current foundation calculation methods fail to consider the contribution of tower stiffness to foundation force coordination, which inevitably leads to an underestimation of the foundation bearing capacity, resulting in increased foundation engineering workload and low economic benefits. Summary of the Invention

[0003] This invention addresses the problem that existing transmission line foundation designs are calculated based on independent foundations, without considering the contribution of tower stiffness to the synergistic load-bearing of the foundation. By providing a transmission tower foundation design method that considers the combined effects of the tower and the foundation, this method fully considers the contribution of tower stiffness to the foundation's bearing capacity and deformation, saving foundation engineering effort and improving economic efficiency.

[0004] To achieve the above-mentioned purpose of the invention, the present invention provides a transmission tower foundation design method that takes into account the combined effect of the tower base. An overall model of the tower is established in simulation software, and horizontal and vertical loads are applied to the tower base. The loads increase step by step from small to large to obtain a load-displacement curve. The horizontal and vertical stiffness at the tower base is determined based on the load-displacement curve.

[0005] Based on the principle of stiffness equivalence, an arch beam is established. By adjusting its cross-sectional area and arch height parameters, the stiffness in two directions at the arch foot is made equal to the horizontal and vertical stiffness at the tower foot.

[0006] Four foundation models of the tower are established, and adjacent foundations are connected by the aforementioned arched beams.

[0007] Input geological parameters and apply the tower base force calculated by the tower to the top of the foundation to perform an overall foundation analysis to obtain the foundation dimensions that meet the bearing capacity and deformation requirements.

[0008] Furthermore, in the load-displacement curve, the load-displacement changes linearly, and the load / displacement is used as its stiffness.

[0009] Positive effects of this invention: It fully considers the contribution of tower stiffness to foundation bearing capacity and deformation. Conventional power transmission line projects typically use over ten different tower types, but often hundreds or even thousands of foundations. Simplifying the tower into an arched beam with uniform stiffness avoids the need to build the entire tower model and foundation simultaneously, simplifying foundation modeling and facilitating batch foundation calculations, significantly improving computational efficiency. This method has been proven to be safe and reliable, reducing foundation engineering workload by over 5%, and delivering significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the stiffness calculation at the tower foot;

[0011] Figure 2 It is a simplified calculation diagram considering the contribution of tower stiffness;

[0012] Figure 3 is a schematic diagram of the load-displacement curve;

[0013] The markings in the attached figure are as follows: 1. Horizontal load; 2. Vertical load; 3. Foundation model; 4. Arched beam. DETAILED DESCRIPTION

[0014] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a transmission tower foundation design method considering the combined effect of the tower and the base of the present invention in conjunction with the accompanying drawings.

[0015] Reference Figure 1 , establish a whole model of a certain tower in structural analysis or finite element software, apply horizontal load 1 and vertical load 2 to the tower foot respectively, and increase the load step by step from small to large to obtain the load-displacement curve. For example, its horizontal load-displacement curve is as follows Figure 3 shown.

[0016] The load-displacement changes basically linearly, and the load / displacement is used as its stiffness. That is, the slope of the curve can be used to obtain the horizontal stiffness at the tower foot, which is 1038N / mm. Similarly, the vertical stiffness can be obtained.

[0017] Based on the principle of stiffness equivalence, an arch beam 4 is established. By adjusting its parameters such as cross-sectional area and arch height, the stiffness in both directions at the arch foot is made equal to the horizontal and vertical stiffness at the tower foot.

[0018] Reference Figure 2Four foundation models 3 were built for the tower. Adjacent foundation models 3 were connected by the aforementioned arched beams 4. This transformed the previously independent foundations into a single, integrated foundation connected by arched beams 4, allowing for coordinated load bearing. Geological parameters were input, and the calculated tower base forces were applied to the tops of the foundations to perform an overall foundation analysis, determining foundation dimensions that met the required bearing capacity and deformation requirements.

[0019] Through comparative analysis, it can be seen that the foundation connected by coupling beams has better integrity and higher bearing capacity. In other words, the foundation size with coupling beams is smaller to achieve the same bearing capacity, which saves foundation engineering volume and reduces foundation investment.

Claims

1. A transmission tower foundation design method considering the combined effect of tower and base, characterized by: The whole model of the tower is established in the simulation software. The horizontal load (1) and vertical load (2) are applied to the tower foot respectively. The load increases step by step from small to large to obtain the load-displacement curve. The horizontal and vertical stiffness of the tower foot is determined according to the load-displacement curve. Based on the principle of stiffness equivalence, an arch beam (4) is established. By adjusting its cross-sectional area and arch height parameters, the stiffness of the arch foot in two directions is made equal to the horizontal stiffness and vertical stiffness of the tower foot. Establish four foundation models (3) of the iron tower, and connect adjacent foundation models (3) through the aforementioned arched beams (4); Input geological parameters and apply the tower base force calculated by the tower to the top of the foundation to perform an overall foundation analysis to obtain the foundation dimensions that meet the bearing capacity and deformation requirements.

2. The method for designing a transmission tower foundation considering the combined effect of the tower and the base according to claim 1, characterized in that: In the load-displacement curve, the load-displacement changes linearly, and the load / displacement is used as the stiffness.

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