Analysis of uplift bearing capacity of tower spread footing in mudstone area under water seepage
[Objective]Mudstone is prone to expansion and disintegration or even degradation in water,which has a negative im-pact on the uplift bearing capacity of transmission tower foundation.It is urgent to study the uplift bearing characteristics of tower foundation under water seepage.[Methods]Based on the indoor test result of mudstone,this paper uses finite element software to establish the calculation model of the enlarged bottom foundation in mudstone,and introduces the method of temperature field analogy humidity field to simulate the expansion and deterioration of mudstone foundation after soaking,and studies the uplift bearing characteristics of the enlarged bottom foundation.On this basis,the specific reasons for the decrease of ultimate pull-out bearing capacity of belled foundation after immersion and infiltration of mudstone foundation are analyzed.The difference of ulti-mate uplift bearing capacity and the relationship between bearing capacity and buried depth under three working conditions of nat-ural state,immersion infiltration and saturation state of mudstone foundation are compared.[Results]The result show that in-creasing the buried depth of the foundation can improve the ultimate pull-out bearing capacity,but the growth is the slowest under saturated conditions.The influence of foundation immersion and infiltration on the ultimate uplift bearing capacity of the founda-tion decreases with the increase of the buried depth of the foundation.The ultimate uplift bearing capacity of the foundation with 2.0 m buried depth is only 63.2％of that in the natural state,while that with 5.0 m buiied depth is 94.2％.[Conclusion]The main reason for the decrease of ultimate uplift bearing capacity of foundation caused by foundation immersion is the deterioration of foundation mechanical parameters and the decrease of shear strength.The research result can provide some reference for the design of tower foundation in mudstone area.
mudstoneuplift bearing capacityspread footingnumerical simulationtemperature field
万方数据
维普
