Numerical Analysis Of Bearing Behavior Of Excavated Foundation In Transmission Line Under Combined Loads

The excavation foundation of transmission lines is to excavate the soil into foundation pits by using mechanical or manpower methods,and then to complete the construction of reinforced concrete skeletons in the foundation pits.Because of its outstanding advantages of small amount of soil,easy construction,reduced the losing of water and soil,and environmental protection,it is widely used in poles of overhead power transmission lines.In actual engineering,the load conditions of the towers of the transmission line are more complex.However,the research on the load-bearing characteristics of the excavation foundation under complex loading conditions is limited.Therefore,it is necessary to have a bearing mechanism under different load conditions.And destruction modes are studied.Because there are many factors affecting the excavation of the foundation bearing capacity,it will be very difficult to use field engineering test methods.Therefore,this paper uses the ABAQUS large-scale finite element software to perform numerical simulation analysis on the joint action of the excavation foundation and surrounding soil.Among them,the effect of the elastic modulus E of the soil on the load-displacement curve is eliminated by the normalization method,and a method for judging the basic ultimate bearing capacity based on the normalized load-displacement curve is proposed.In this paper,the finite element calculation model is first established when the foundation is subjected to individual vertical and horizontal loads.The loading method is based on displacement loading method.The influence of soil parameters on the ultimate bearing capacity of one-way foundation under different depth ratios is discussed.Strain cloud maps and displacement vector cloud diagrams analyze the failure modes of the foundation.Then,the finite element model of high grounding excavation foundation subjected to horizontal loads was established to simulate the conditions under which the foundation is subjected to horizontal forces and bending moments.The failure mechanism and load bearing characteristics under H-M combined loading were studied and the failure envelope was plotted.Comparing the numerical calculation results with the centrifuge test,the results of the two methods are close to each other,verifying the accuracy of the numerical analysis.Then,based on the ultimate bearing capacity of each unidirectional load,the load-displacement step loading method is used to analyze the failure mode and bearing characteristics of the foundation under the combined effect of horizontal force and uplift force(H-V)and the numerical simulation results are obtained.Conclusions and literature have been compared with field test results.Finally,based on the study of combined loads of H-M and H-V,the failure mode and load-bearing characteristics of H-M-V three-way loads are analyzed,and the basic failure envelope under H-M-V combination is plotted.According to the load-displacement,the basic failure envelope,the plastic strain cloud around the foundation,and the displacement vector cloud diagram,the interaction between the three loadings was analyzed.The basic failure mechanism and load bearing characteristics under different conditions analyzed in this paper provide reference for the design of transmission line digging foundation engineering.