Experimental Study On Bearing Characteristics Of Horizontal Multi-directional Single Piles In Clay

The previous studies on the laterally loaded pile in clay usually consider the loads along one particular horizontal direction;however,the horizontal loads can be much more complicated in many cases.For example,the horizontal forces exerted on pile foundations,as induced by wind,waves or earthquakes,are usually multidirectional,which vary in both magnitude and direction during loading process.The results of model tests on the pile in sand indicated that the horizontal bearing capacity of the pile under multidirectional paths is usually lower than its counterpart under the unidirectional path,and the degree of reduction depends on the characteristics of the loading paths.In this paper,behavior of a single pile in both soft clay and stiff clay and under monotonic and cyclic multidirectional paths is systematically studied by use of the laboratory model test.The main contents of this paper are as follows:(1)The background of utilization of piles to resist lateral loads is briefly introduced,and the research progress on this topic at home and abroad is summarized.Potential research direction is determined by identifying the scantiness in current research.(2)The response of a single pile in soft and stiff clay and under various monotonic multidirectional paths is studied through the model tests.It is found that the loading path has a significant effect on the horizontal bearing capacity of pile.(3)By use of the model tests,the response of a single pile along different horizontal directions,after it has been subject to unidirectional cyclic loading,is studied.The effect of the unidirectional cyclic loading on the bearing capacity of single pile at different horizontal directions is revealed.(4)The response of a single pile in soft and stiff clay and under different multidirectional horizontal loading is studied by the model tests.Comparison of the test results shows that the characteristics of the load-displacement curve under the multidirectional path are obviously different from that under the unidirectional path,and the maximum load in the former is always lower than that in the latter.(5)The observed phenomena and results of the tests in soft and stiff clay are compared and analyzed.It is found that the effect of loading path on the soil-pile interaction is more significant in soft clay.