Cracking Mechanism And Reinforcement Measures Of Tower Foundation Columns Under External Force And Temperature

In recent years,with the improvement of transmission line engineering construction requirements,the upper load and joint stiffness of the transmission tower base have become larger and larger,which puts higher requirements on the foundation bearing capacity and crack resistance performance.At present,more research at home and abroad focuses on the ultimate bearing capacity.In some UHV transmission line projects,the phenomenon of foundation cracking appears,and it is obvious that the study of foundation cracks is also very important.In this paper,the transmission tower project of the Certain Design Institute is taken as the research object.The causes of the foundation cracks are analyzed from the two angles of external force and temperature,and corresponding reinforcement measures are proposed.The main research contents and achievements include the following three aspects:(1)Studying the physical properties and material strength of concrete,and introducing the mechanism of hydration heat and temperature stress generation of mass concrete during construction.Using the APDL language in ANSYS finite element,the process simulation of the temperature field and temperature stress of the foundation concrete pouring process is compiled,and the distribution law of temperature field and stress is understood.The simulation results show that the maximum tensile stress in the pouring cycle is 1.45 MPa.And the maximum tensile stress is always less than the tensile strength during the age,and the concrete stress of the column causes less cracking.The effect of structural steel bars on concrete cracking is proposed and verified.The results show that the fine and dense steel bars have better anti-cracking effect.The whole process temperature detection was carried out for the concrete floor project pouring,and specific temperature control measures were proposed by comparing the finite element with the monitoring results.(2)Explain the action mechanism and construction technology of steel mesh reinforcement technology;deduct and establish the theoretical solution of single anchor tension,which lays a theoretical foundation for elastic analysis of foundation column anchor;compares whether there is any elastic work phase The influence of the steel mesh on the different safety factors of the concrete demonstrates the effect that the steel mesh can exert on the compression,and other reinforcement measures are needed for the tension.(3)The finite element analysis software ABAQUS's plastic damage constitutive relation is used to simulate the reinforcement process of the steel mesh.The results show that the ultimate bearing capacity of the steel mesh can be increased by 13% under pressure conditions.The reinforcement factors affecting the reinforcement effect of the steel mesh are obtained,and the load-displacement curves under different influence factors are obtained,and the effect of reinforcement is comprehensively evaluated to provide a basis for optimizing the layout of the mesh.This paper starts from the three aspects of theory,experiment and finite element to study the cracking reasons and prevention measures of the foundation.The finished work has certain reference value for the crack prevention research of the foundation engineering.