Study On Bearing Behavior Of The Single Pile Under Combined Lateral And Axial Loads

As we all know,the single pile foundation is one of the most important basic forms in foundation design.The single pile foundation of offshore drilling platforms,large transmission towers and offshore wind farms,should bear axial loads delivered from the upper structure.Then it needs to bear huge lateral loads generated by winds,waves,earthquakes and so on.The conventional methods for analysis of piles based on sub-grade reaction methods do not account for the interaction between the axial and lateral loads.It is of great significance to study the bearing behavior of the single pile under combined axial and lateral loads,so as to calculate the bearing capacity of single pile more accurately and reasonably.It is of great importance for the optimization design of pile foundation and the safety of pile foundation engineering.The main works carried out in this paper are as follows: This paper present recent works about the single pile under combined lateral and axial loads.The existing theory and calculation methods of pile foundations are introduced in detail;Indoor model tests have been completed to evaluate the influence of this interaction on both lateral and axial bearing capacity of the single pile under combined loads;Based on the field test in Gansu Province,a series of three-dimensional finite differences analyses is conducted to evaluate the interaction effects of the one loading on the other.The influence of related parameters,such as soil conditions and pile slenderness(L/B)ratio have also been studied in this paper.The results indicate that:(1)When the single pile is subjected to both lateral and axial loads,there is a coupling effect between lateral and axial loads.The coupling effect is affected by the soil conditions around pile and t pile slenderness(L/B)ratio.(2)In clayed soils,this coupling effect weakens both lateral and axial ultimate bearing capacity.The weakening degree of ultimate bearing capacity is greatly affected by the degree of soft and hard clay.The softer the clay,the greater the weakening of ultimate bearing capacity of the single pile.(3)In sandy soils,this coupling effect increases both lateral and axial ultimate bearing capacity.Axial loads in sandy soils with different compactness have little difference in the increase of ultimate horizontal bearing capacity.On the contrary,the improvement degree of axial ultimate bearing capacity under lateral loads is greatly affected by the compactness of sandy soil.The greater the compactness of sandy soil,the greater the improvement degree of axial ultimate bearing capacity under horizontal load.(4)When pile slenderness(L/B)ratio varies in clay soils,the weakening degree of axial load on lateral ultimate bearing capacity is nearly affected.On the contrary,the weakening degree of axial ultimate bearing capacity under lateral loads is related to the ratio of length to diameter.Which is,when pile slenderness(L/B)ratio is large,the axial ultimate bearing capacity is greatly affected by lateral loads.