Study On Ground Motion Characteristics And Wave Input Of Valley Site Based On Ibiem

Most of my country’s hydropower resources are concentrated in the southwest region,which is located in an active seismic zone,where strong earthquakes and aftershocks occur frequently.The hydropower plant in the hydraulic structure is the main place where technicians work and water conservancy equipment operates,and its anti-seismic safety needs to be considered emphatically.For a period of time after the earthquake,it is often accompanied by high-frequency aftershocks.After the main shock damages the structure,it may encounter aftershocks again if it cannot be reinforced in a short period of time.The damage of hydraulic structures damaged by earthquakes will be further deepened under the action of aftershocks,especially some factors that play a key role in the damage of hydraulic structures will greatly enhance the damage of buildings,However,the current hydraulic seismic research only considers the response of the hydropower plant under the action of a single main shock,and the response of the hydropower plant to the combined main and aftershocks in strong earthquake areas is an important issue that needs to be solved urgently.In this paper,through the screening of the real main aftershock sequence and the construction of the artificial main aftershock sequence,the main aftershock sequence input and the oblique seismic wave input method are combined to study the three-dimensional hydropower plant under the far-field and near-fault SV wave and P wave oblique incidence excitation.Structural Response Law.The main work contents and conclusions include:(1)Mainly studied the selection and construction method of the main aftershock sequence and the method of seismic wave oblique incidence,rationally selected the real main aftershock sequence and constructed the artificial main aftershock sequence,and deduced the input method of seismic wave oblique incidence,combined the main aftershock sequence and viscous The elastic boundary seismic wave oblique input method is combined to achieve the purpose of inputting the foundation boundary of the plant model.(2)The far-field main aftershock sequence was selected from strong earthquake record databases such as Pacific Earthquake Center(PEER)NGA-WEST,Japan Institute of Disaster Prevention Science(NIED)K-NET and KIK-NET,and a three-dimensional model of the hydropower plant was constructed.The response of the far-field main aftershock sequence to the powerhouse structure is obtained.The calculation results show that under the same incident angle,the joint action of the main aftershock sequence has more obvious damage to the structure than the action of a single main shock,and the damage and cracking range is larger compared with the case of PGAMS<PGAAS and PGAMS>PGAAS,the damage increment caused by aftershocks is larger.The power plant damage under the action of the main aftershock sequence decreases with the increase of the incident angle.The typical concrete unit damage of the upper wall of the factory building,the Mises stress of the typical steel bar unit,the acceleration distribution coefficient of the upper wall of the factory building,and the dynamic principal stress of the upper concrete structure also increase rapidly in a short time after the peak seismic wave acceleration,and PGAMS<PGAAS The typical concrete damage evolution,reinforcement stress,upper wall acceleration distribution coefficient and dynamic principal stress of the concrete structure are also greater than the case of PGAMS>PGAAS.(3)The real main aftershock sequence near the fault was selected and some artificial main aftershock sequences were constructed,and the concrete damage of the powerhouse structure,the evolution of steel stress,the maximum story displacement angle of the upper wall structure and the The relative displacement of the upper and lower corbels along the river direction.The calculation results show that the cumulative damage to the upper part of the building under the acti on of the main aftershock sequence decreases with the increase of the incident angle,the pulse type of the main aftershock sequence will cause more serious damage than the non-pulse type,and the The stress of steel bars is also greater than that of non-pulse-type steel bars.When PGAMS<PGAAS,pulse-type main aftershocks cause extensive damage during the combined action of main and aftershocks,and the stress of steel bars increases gradually,and the safety margin decreases obviously.The maximum interstory,displacement angle of the upper wall of the factory building and the relative displacement of the upper and lower corbels along the river direction increase with the ratio of the ground motion intensity index PGAAS/PGAMS.The maximum interstory displacement angle of the upper wall and the relative displacement of the upper and lower corbels along the river direction of the pulse-type main aftershock are larger than those of the non-pulse-type main aftershock.(4)By calculating the development process and proportion of various parameters in the energy balance equation,the energy response of the main body of the powerhouse of the hydropower station at different incident angles under the condition of oblique incidence of the main aftershock sequence near the fault is obtained,and the damage of the concrete structure of the powerhouse is analyzed,the dynamic principal stress of the steel grid roof,the dynamic principal stress of concrete beams,columns and other main seismic responses.The results show that the energ y response and other responses of the powerhouse increase with the increase of the incident angle,and the energy response and other responses of the powerhouse under the action of the near-fault pulse PGAMS<PGAAS type main aftershock sequence are stronger than those of the other three types of main aftershocks sequence.