| At present,China's marine engineering is in a period of vigorous development,and a large number of major construction projects,such as cross sea bridges,undersea tunnels,artificial islands and reefs,and offshore platforms,have been completed.With the national "ocean power" strategy,the "one belt and one road" initiative and the development and construction of the South China Sea Islands and reefs,the construction of the sea area project will be more frequent.However,the intensity and frequency of seismic activities in China's offshore areas are high,and there have been many strong earthquakes with magnitude of 6.0 or above in history.Therefore,the problems of engineering ground motion and disaster risk in the sea area are becoming increasingly prominent,which has become a hot issue in the scientific and Engineering circles in recent years.In view of some scientific problems exposed in the current seismic response analysis of the actual sea area engineering site,such as neglecting the influence of the self weight stress of the overlying sea water and the coupling effect of water and soil,still using the equivalent linearization method of one-dimensional frequency domain consistent with the land area engineering,inconsistent with the actual sea area saturated two-dimensional complex medium system,and insufficient research on the influence of the sea area soft soil on the sea area ground motion Through the combination of theoretical analysis and numerical simulation,this paper focuses on the differences of the peak value and spectrum characteristics of the ground motion in the land sea area,the influence of the self weight of the overlying sea water on the peak value and spectrum characteristics of the ground motion in the sea area,and the influence of the soft soil layer in the sea area on the peak value and spectrum characteristics of the ground motion on the seabed surface.Next is the main content and work of this paper.1.Under two different seismic wave inputs,no matter P wave or SV wave is input,there are some differences in peak acceleration and acceleration response spectrum between land site and sea site(seabed surface).The amplification coefficient and acceleration response spectrum of two different input seismic waves are quite different.2.For seismic wave as SV wave input,the peak acceleration of seabed surface of sea area site is less than that of land site,and the acceleration response spectrum of sea area site is lower in small period than that of land site,and reverse in large period.For seismic wave as P wave input,the peak acceleration of seabed surface in sea area is greater than that of land area,and the acceleration response spectrum of sea area is greater than that of land area in small period.The influence of the depth of overlying sea water on the ground motion under the input of SV wave can be ignored,but the influence on the ground motion under the input of P wave will be gradually reduced3.No matter in sea area or land area,the presence of silt soft soil will increase the amplification coefficient of the site and the peak value of the site response spectrum.From the acceleration response spectrum,it can be seen that the influence of soft soil on the smaller period is more obvious.The amplification effect of the peak acceleration of the silt soft soil layer in the sea area is greater than that of the soft soil layer in the land area.And the peak value of acceleration response spectrum of marine silt soft soil site is compared with that of land soft soil site.4.The difference of peak acceleration and acceleration response spectrum between sea area and sea area soft soil field is calculated and compared by equivalent linearization software LSSRLI-1 and FLAC 3D,and it is concluded that the input ground motion intensity is small,The results of FLAC 3D dynamic analysis overcome the influence of LSSRLI-1 under estimation of surface seismic response(high frequency component)This paper can provide a new idea and approach for the study of seismic field effect in the sea area,and can further improve the seismic capacity of construction projects in the coastal area and sea area.It has important scientific value and engineering significance for promoting the development of marine soil dynamics and engineering earthquake in the sea area. |
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