| Numerical simulation is an important means to solve the problem of saturated soilstructure dynamic interaction,and an effective wave input method is a key link to ensure the accuracy of numerical simulation of saturated soil-structure dynamic interaction under earthquake action.In this paper,the seismic wave input method in the analysis of saturated soil-structure dynamic interaction problem is systematically studied.Based on the single-phase medium artificial boundary sub-structure method,the equivalent input seismic load is derived for the fluid-structure interaction u-p form governing equation considered the solid displacement and pore pressure as the basic unknown quantities.The expression,combined with the fluid-solid coupling pore pressure element and the saturated viscoelastic dynamic artificial boundary conditions,proposes a new method of inputting ground motion for the saturated soil-structure dynamic interaction problem,and implements it in the general software ABAQUS.Combined with the proposed seismic wave input method,the dynamic response characteristics of subway stations in a saturated foundation site under different types of seismic waves are studied.The main research contents and results of this article are as follows:(1)A new input method suitable for numerical simulation of saturated-soil structure dynamic interaction is proposed.Starting from the fluid-structure interaction dynamic equation in the u-p form of fluid-saturated media,the artificial boundary substructure method proposed by Liu Jingbo is extended to saturated two-phase media,and the calculation expression of equivalent input seismic load for saturated two-phase media is deduced,which is a new method.The proposal laid a theoretical foundation;in the realization of the new input method,it was mainly aimed at how to implement the method in general numerical simulation software as a starting point,combining the fluid-solid coupling pore pressure unit and the dynamic artificial boundary of the saturated porous medium.It is implemented in the general-purpose software ABAQUS.At the same time,an auxiliary program for generating the viscoelastic artificial boundary file(Spring&dashpot.inp)is developed based on the MATLAB computing platform,and the Python language is used to write the input file for generating the equivalent input seismic load(Amp&Cload.inp).Script provides technical support for the realization of the new input method.(2)The proposed new method is used in the study of the dynamic response characteristics of subway stations in saturated foundation sites,and the effects of the soil types and incident wave angles on the dynamic response of subway stations under different types of seismic waves are analyzed.After the new method was proposed,the saturated free field example was first used to verify that the new input method can be applied to the vertical incidence and oblique incidence of seismic waves.Then,according to the numerical analysis model of the subway station in the saturated foundation site,the seismic response characteristics of the subway station in the single-phase medium site and the saturated medium site under the action of different types of seismic waves,and the influence of the incident angle on the dynamic characteristics of the subway station are studied.The results show that: Due to the existence of pore water,the soil-structure dynamic interaction phenomenon in saturated sites is more obvious;in saturated sites,compared with SV waves,the change of incident angle has a greater impact on P waves;the dynamic response characteristics of underground structures are affected by types of seismic wave has a greater impact. |
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