Seismic Response Analysis Of Drainage Rigid Pile Group Pile-soil System In Liquefied Lateral Spreading Site

Under strong earthquakes,the liquefied lateral spreading site is prone to large lateral displacement.The lateral flow of sand liquefaction is one of the main reasons for a large number of pile foundation damage,ground collapse and superstructure damage.There are many earthquakes all over the world,and the lateral expansion of liquefaction caused by earthquakes has caused serious personal harm and economic losses to all parts of the world.More and more scholars are following with interest in this kind of problem and have done a lot of pile-soil dynamic interaction research,and they are also looking for effective means to deal with the lateral expansion of sand liquefaction.The drainage method is an effective measure to deal with the liquefied site,but the flexible gravel piles in the past are difficult to meet the requirements of modern buildings for the bearing capacity.Therefore,Professor Liu Hanlong developed a new type of drainage rigid pile,which combines the vertical drainage channel with the rigid pile.This kind of piles can not only limit seismic liquefaction but also meet the requirements of bearing capacity.Most of the existing researches on drainage rigid piles focus on the study of the soil characteristics of the liquefied free site,verifying the drainage effect of the drainage rigid piles,but for the lateral spread site of the liquefaction,there are few studies on the dynamic characteristics of the drainage rigid pile foundations.Based on this,this paper will carry out the shaking table experiment of the drainage rigid pile group-soil system of the liquefaction lateral spread site,comparing the ordinary rigid pile group and the drainage rigid pile group,to verify the effect of the drainage rigid pile group to strengthen the liquefaction expansion site,and to pay attention to the internal force response and displacement response of pile groups under dynamic action.In this experiment,a group pile cap structure of drainage rigid pile is designed.This not only provides a certain reference basis for the seismic design requirements of drainage rigid pile groups,but also studies the possibility of the application of rigid pile group in wharf or breakwater.It is called drainage rigid pile group pile foundation in the following.The specific research content is as follows:(1)A series of shaking table test were carried out between drainage rigid pile group pile and ordinary rigid pile group pile foundation,basing on 3×3 pile group-cap-upper overlying structure.The comparative analysis of sand pore pressure,acceleration response,quay wall displacement and ground settlement shows that the drainage rigid pile group can effectively limit the seismic liquefaction and lateral expansion of sand soil,and it is an effective means to deal with the lateral expansion of the liquefaction site.(2)By changing the pile spacing,the relative density of the foundation and the distance between the quay wall and the pile group,the shaking table experiment of ordinary rigid pile groups and drainage rigid pile groups is carried out to study their influence on the disposal of liquefaction expansion site.The results show that the increase of the pile spacing will weaken the drainage effect of the drainage rigid pile group,and the increase of the relative density of the foundation will help the drainage rigid pile group to reinforce the liquefaction expansion site,which can limit the lateral deformation and reduce the degree of foundation liquefaction.(3)On the basis of verifying the anti-liquefaction performance of drained rigid piles,a series of tests were carried out to study the internal force and displacement response of the drained rigid pile groups under dynamic action.The distribution law of the pile body bending moment of the pile group and the difference of the force of the single pile at each position are obtained.This paper also studies the influence of different pile spacing and the relative density of the foundation on the dynamic response of pile groups.All of them will provide a certain basis for the seismic design of drainage rigid pile groups.