Model Test Study On Earth Pressure And Bearing Capacity Of Jacked Pipe Pile In Sand

Jacked pipe pile has many advantages such as fast construction,no pollution,low noise,no vibration,no impact,and so on,so it is widely used,especially in soft soil and other foundations.Jacked pipe pile is a squeezed pile,which is squeezed by the soil during the penetration process.The pile-soil interaction occurs in the single pile,so that the density of the surrounding soil changes,and then the earth pressure will change accordingly.After the completion of the increase with time,due to the soil of self-stabilization and remodeling,bearing capacity will be correspondingly improved.Therefore,it is effective to estimate the squeezing effect of the jacked pipe pile,to study the stress variation of the surrounding soil and its bearing characteristics,which is of great significance to the engineering.In this paper,the characteristics of the pile and the bearing capacity of the jacked pipe pile are summarized.At the same time,this paper focuses on the following research:(1)The theoretical calculation of the bearing capacity of the two kinds of piles is deduced in detail,including the comparison of the bearing capacity of the pile end and the formula of the foundation bearing capacity of the pile foundation.The general solution of the normal stress,radial stress and plastic zone displacement of the pile during the process of the jacked pipe pile is deduced.The general solution of the average volume of the plastic zone is given.On the basis of the final pressure of the pile the formula of the bearing capacity of the pile is given,and the bearing capacity of the pile is predicted by this formula.The classical formula of bearing capacity of two kinds of pile foundation is introduced.(2)In order to explore the interaction between pile and soil,it is necessary to measure the earth pressure of pile-soil section.Three methods of measuring earth pressure are put forward: membrane pressure sensor,earth pressure cell and cantilever earth pressure measuring device.Three methods were used for indoor calibration tests.Cantilever earth pressure measurement device can reduce the soil arching effect,the advantages of the earth pressure cell in the model pile test is more prominent,the film pressure sensor to be further studied.(3)Based on the vertical loading system of the jacked pipe pressure pile,the equipment is improved,and the rigidity of the pile system is improved by the sliding plate instead of the original slider.The vertical precision of the pile penetrating process is further improved.PLC servo motor cylinder control,to achieve automatic,stable and accurate loading.A multifunctional model test pile is developed independently.The model pile can accurately measure the earth pressure and the resistance of the pile end through the embedded earth pressure cell and its pile end force sensor.(4)In the model box,jacked pipe pile penetration process and the jacked load test were carried out to explore the earth pressure at each pile depth after the completion of the different pile speed,and the pile side friction,pile end resistance,pile force and pile end residual stress.Study on bearing capacity and regularity of jacked pipe single pile in single sand by jacked load test.The results of this experiment are compared with the theoretical calculation methods of bearing capacity,and the interrelations and differences between them are explored.