Experimental Study On Response Of Gravel Pile Under Dynamic Loading

As a kind of foundation treatment technology,the gravel pile composite foundation has developed in practice and has been widely used in various weak foundation treatments.Its main advantages are simple construction,short construction period and low cost.However,there are also some problems:(a)Gravel piles have poor deformation resistance and when subjected to the upper load,piles have large settlement deformation(b)The gravel pile is composed of loose particles and has small cohesion.It is greatly affected by the surrounding earth pressureAt present,some mechanical research results on the participation of bulk materials in the structure are still in the stage of discussion and evaluation.,especially the research used to guide engineering practice is very few.For example,there are some researches on how to “unchoking” materials and avoid the “plugging” phenomenon of materials,but little research has been done on how to use the “plugging” of bulk materials in the reverse direction.Dynamic load refers to the load that changes with time.It is not necessarily a cyclical change.It may also be an irregular,irregularly changing load.As long as it changes with time,it is a dynamic load.In this paper,the triaxial test is used to test the shear strength and its parameters of graded gravel piles affected by different vibration factors.Furthermore,the paper analyzes the particle state,particle slip and the law of change affected by vibration during the loading process of gravel piles.According to the measured data of the triaxial test,compare the changes of the stress-strain curve,use the classical C-M yield criterion to draw the shear strength damage envelope,and determin the influence of the shear strength formula and parameters after vibration..Through the test and data processing,after different vibration times and waveform vibrations,the stress-strain relationship curve,the molar circle,the shear strength failure envelope diagram and the shear strength parameters of the gravel pile can be obtained.Therefore,the variation law of shear strength and stress movement of gravel pile affected by vibration were analyzed.After disturbing the gravel pile with different vibration times and the same waveform,the data processing and analysis results of the triaxial test of the gravel pile are as follows:The amplitude is within the allowable deformation control range of the gravel pile.After the vibration,the shear strength of the gravel pile is improved,and there is a vibration order.The internal friction angle of the gravel pile can reach the maximum.Defined as the number of extreme vibrations.After the number of extremevibrations,the friction angle of the gravel pile shows a weak wave trend with the number of vibrations increasing.Therefore,it is bold to guess that the internal friction angle of the gravel pile is less than the internal friction angle of the unvibrated gravel pile if it is subjected to a certain number of vibrations,and is initially defined as the number of pole vibrations.Multi-stage gravel piles are more affected by the number of vibrations than single-stage gravel piles,and the number of vibrations tolerated is generally higher than that of single-grained gravel piles.However,the gravel particles are pebbles or spherical particles.Gravel gravel piles generally have the lowest number of vibrations tolerated.After disturbing the gravel pile with different vibration waveforms and the same number of vibrations,the data processing and analysis results of the triaxial test of the gravel pile are as follows:The internal particles of the gravel pile not only have vertical particle slip under vibration,but also horizontal to particle slip,and the horizontal wave generated by the triangular wave slips less than the square wave and sine wave.Therefore,combined with the particle composition of different grades,the degree of reaction produced by pairing the three waveforms at different levels is quite different.There is a gap between the particles of the single-grained gravel pile,but there is no small-size filler in the void,and the void is reduced by the triangular wave vibration.Because the triangular wave vibrating particles are vertically slipped and destroy the interlocking,the horizontal slip of the particles is small and the new bite cooperation is less,the single-grained gravel pile has the smallest internal friction angle and the minimum shear strength after the triangular wave vibration.The multi-stage gravel pile has many interstices and small particle filling.Under the horizontal displacement,the small particles are more likely to leak downward.After the leakage,the bite cooperation between the gravel piles is seriously damaged.Therefore,the multi-staged gravel pile has the largest internal friction angle and the highest shear strength after the triangular wave vibration.After the sine wave is vibrated,the corresponding internal friction angle is the smallest and the shear strength is the smallest.