Study On Design Method Of Short Piles-Cap-Foundation Based On Interaction

The Short Piles-Cap-Foundation is a new type of foundation,which is excavated in the upper part,the lower part is short pile and the common force is considered.In the process of pile foundation design,the pile foundation design is optimized by considering the reaction force of the foundation soil under the pile cap.This new type of foundation has important practical value in some specific geological complex areas.Through the optimization of this type of pile foundation,the pile foundation can meet the requirements of safety and economy.This paper through the investigation,comparison,summary way summarized the definition of short pile,and through the FLAC3D numerical simulation software to simulate the different pile length(L=2m,3m,4m,4.5m,5m,5.5m,6m,7m,8m,9m,10m,11m)the bearing capacity of the pile when the pile length is less than 4m.When the bearing capacity is low;when the pile length is 4～6m,its bearing capacity is increased greatly,probably around 35%.When the pile length is 6m,the bearing capacity is not significantly improved.In summary,this paper defines the short pile length 4m≤L≤6m,and the ratio of length to diameter 6<L/D<20.Systematic analysis of the stress state of short pile and soil interaction,the interaction of pile and soil mechanism of short pile foundation pile simulation experiment through FLAC3D numerical simulation,simulation of the different pile length short pile(L=4,5,6m),different pile spacing(Sa=2d,3d,4d,6d)short pile cap soil anti force changes.The results show that the reaction force of the pile cap is directly proportional to the pile spacing.When the pile spacing is Sa=4d-6d,the soil of the pile cap can fully play its role.The maximum value of the reaction force of the pile cap is located near the inner side of the side column,followed by the corner of the pile cap.In order to study the influence of different soil layers on the Short Piles-Cap-Foundation,the pile group simulation experiment was carried out under the condition of different soil layers.The test includes changes of soil with different pile(clay,sand and gravel soil),different pile changes(clay,sand,gravel soil),analysis of effects of soil changes on the load of raft ratio and short pile cap foundation settlement,and the connection of the two.The experimental results show that the maximum load sharing ratio is the largest and the settlement is the lowest.Through the analysis and comparison of the Q-s curves of different soil layers and the load sharing ratio curve of the pile cap,it is found that the settlement load is smaller than that of the soil layers.Based on the above research results,this paper considers The Short Piles-Cap-Foundation should be optimized for the type of shallow foundation,according to the design principle of bearing capacity and displacement control standards,the overall design idea is:starting from the natural foundation design,to meet the bearing capacity of the foundation under the condition of short pile in order to reduce the settlement and to set up a certain number of piles.Based on the study of the interaction design method and the key data,the design process of short pile cap soil interaction is completed.The design method of short pile cap soil interaction is used to redesign the actual project,and is verified by the numerical simulation software.The design method based on the above theoretical and short pile soil interaction,the use of VB6.0 programming software to complete the program design of short pile foundation ",which makes the design project of the foundation is simple and effective,improve the efficiency of application in practical engineering.