Study On Influence Of Underlying Karst Cave On Pile Foundation Crossing Scheme And Selection Of Pile Length Parameters

In this paper,the first phase of the No.5 plot in a project in Kunming is taken as the research background,combined with the basic assumptions of elastic mechanics,and analyzed according to the small deflection of the thin plate;GTS NX numerical simulation software is used to consider the vertical earthquake action and the dynamics of the superstructure The response is simulated and calculated,and the stability of the roof of the karst cave is evaluated through the three dimensions of force,displacement,and velocity.The stress,displacement,and velocity feedback of the karst cave-pile foundation system under the action of static and dynamic forces are studied.The influence degree and mechanism of the pile end action position and pile length parameter of the pile foundation finally select the reasonable pile foundation crossing scheme suitable for this project,and choose the reasonable pile length parameter according to the pile foundation action position of the pile foundation.The main research conclusions for the first phase of a plot 5 in Kunming are as follows:(1)Both the through-pile scheme and the non-through-pile scheme can meet the stability requirements of the roof of the karst cave.That is,the position of the pile foundation at the end of the pile can adopt the scheme of the pile end acting on the bottom of the cave or the pile end acting on the roof of the cave;(2)If the non-traversing pile scheme is adopted,that is,the pile end of the pile foundation acts on the roof of the karst cave,the reduction of the pile length can significantly increase the stability of the roof of the karst cave;when the pile length is 22 meters,the roof will lose under dynamic action.Stability and failure;when the pile length is 21 meters,the roof may be unstable and damaged under dynamic action,which needs to be analyzed in detail in accordance with the specific conditions of the site.When the pile length is 20 meters,the stability of the roof of the cave meets the safety requirements.(3)The non-traversing pile scheme is more effective than the traversing pile scheme,that is,the pile end acts on the top of the karst cave than the pile end acts on the bottom of the karst cave.The scope and degree of influence on the karst cave are greater,and the stress concentration on the side wall of the karst cave is more obvious,And the effect is more significant under the action of power.The research content of this paper provides a certain reference for the foundation type selection of the proposed site,and provides corresponding research ideas and methods for the selection of pile foundation parameters when the cave is covered.