Research On Bearing Capacity Of Jacked Pile Group Characteristics And Pile-Pile Interaction In Sandy Soil

In recent years,China has continuously improved the environmental pollution control,while vigorously advocating the prefabricated units should be used in the field of engineering construction to reduce the environmental pollution of construction.In the foundation engineering,the jacked pile is more and more attention by the designers because of its advantages such as small environmental pollution,no noise and vibration pollution,easy to control the quality of the prefabricated piles and the construction speed of faster.This paper briefly describes the development process of jacked pile and its commonly used research methods,the bearing capacity of jacked pile and jacked pile group(double pile)in unsaturated sand soil and the interaction between piles and piles in the process of double pile compaction are studied by model test.The main contents of this paper are as follows:(1)Using multi-function model pile to calibrate the testThe relatively dense sand layer was prepared to carry out calibration test,in the calibration tank,by using the self-developed sand deposition equipment.It is effective to avoid the significant lag of the unloading response of the membrane-type soil pressure box when using the calibration tank to combine the gas standard and sand standard method,and obtains the requirement of satisfying the test precision.One of the most effective ways to reduce the "soil arching effect" that it is possible to use the large-scale soil pressure.While it taking a more linear calibration results,in order to further the pile in the process of the stress characteristics of the study prepared.(2)Adopting multi-function model pile to carry out single pile compression testUsing the existing jacked pile system device,the single pile compression test is carried out on the same two model test pile.The relationship between the compressive strength of the model piles and the load-bearing capacity,the compressive force,the pile tip resistance and the lateral friction of pile are studied.The test results show that the pile pressure and the resistance of pile tip are increased with the depth of pile compression in the 12 D range.The lateral friction of pile and the bearing capacity of pile are non-linear increasing,and with the increase of the pressure depth,the proportion of the pile tip resistance is decreased gradually.On the contrary,the proportion of the pile force is gradually increased with the increase of the pressure depth.(3)Research on bearing capacity of jacked pile group(double pile)The relationship between pile spacing and pile depth or bearing capacity,compressivepile force,pile tip resistance and lateral friction of piles is studied by using different pile spacing in double-pile compression test.According to the test results,the bearing capacity of double piles is gradually increased with the increase of pile spacing,and the bearing capacity of the single pile is approaching two times.The compressive pile force,the pile tip resistance and the lateral friction of the pile are decreasing gradually in the process of post compaction,while gradually approaching the single-pile pressing state;the soil pressure subjected to the first pressed pile body decreases gradually,and then the compressive depth of the pile increases.With the increase of the compressive depth of the post pressure piles,the compressive pile force,the pile tip resistance and the lateral friction of piles are not linearly increased.(4)Study of the interaction between pile and pile in hydrostatic double-pile systemThrough the analysis of the displacement of the first-pressed piles caused by the post-pressed pile,the displacement of the pile body is decreased gradually with the increase of the pile spacing.With the increase of the pressure into the depth of the first pressed into the pile body displacement gradually increased.The more obvious the influence of the “soil arching effect” on the stability of pile body is the more that the pile spacing is smaller or the deeper depth.It is illustrated that the influence range of the new soil stress field produced in the pile-body compaction process is larger with the increase of the pressure depth.