The Structure Optimization And Vibration Test Study Of The Drilling And Pipe Pile

The drilling and pipe pile as a kind of high degree of mechanization,no slurry pollution,easy construction speed and quality control of energy efficient and environmentally friendly new pile type.The special process consists of sinking piles,excavating,and taking soil at the same time.After the single pile has reached the design elevation,the bottom of the pile is closed with concrete,and the pile is then post-grouted.The vertical compressive bearing capacity of the single pile is significantly higher than that of the current static pressure pile and hammer driving,and reduces the damage to the pipe pile with the hammer blow and the holding pressure,which is applicable to the wide range of strata.At present,the connection between the pile pipe piles is also used in the traditional welding process,the welding time is long,which affects the improvement of the overall construction speed.This pile type pile shoe is used now is steel pile boots,cost is high.Therefore,a fast connecting device suitable for the pile type is designed,and a high cost effective pile shoe device is developed,and the anti-seismic model test is carried out.1.The design of a new fast connection device and the method of use with drilling and pipe pile;Through ABAQUS refinement modeling and simulation analysis,this paper studies the performance of its bending,anti-pulling and shear capacity,and verifies that the design meets the requirements of the specification and optimizes its analysis.Results show that the new fast connection device adopts Q460 steel,25 to 30 mm in thickness,the width in 320~360 mm,can not only meet the requirements of bearing capacity of shear,bending,tensile,also can save cost.2.Design a new type of pile shoe with drill and pipe pile;Based on the theory of elastic contact model,is proposed based on the plasticity and crack area is obtained by experiment of the ratio of width and circle the overall width of the ? simplified calculation formula of bearing capacity and pile shoe grade of concrete under different conditions to choose methods and schedule,for this shoe design and production to provide the theoretical basis and the construction guidance;Through the foot pressure test,it is observed that the pile shoe is damaged under the joint action of the bottom pressure crack and side tension crack and splashes all around.The stirrup-bending diameter and concrete strength have positive effect on the bearing capacity.The stirrup-straight diameter has little effect on the bearing capacity,and the diameter of the hoop will affect the flatness of the bottom surface,thus reducing the bearing capacity.Proves the rationality of the simplified calculation formula of bearing capacity of ?,when ? take 0.4,testing the bearing capacity characteristics.3.In seismic performance research results on the basis of summarizing predecessors’ pile,developed an in-plane shear garment and fundamental frequency adjustable round laminar shear box,the canal design while drilling grouting of the interface between pile and soil,the technology and simulation shaking table model test;The dynamic characteristics(self-oscillation frequency and critical damping ratio)of the model system were studied by processing the data of velocity sensor in the model sand soil.The acceleration response law of the model is studied.The effect of the seismic shear box designed by the laboratory on the effect of the boundary effect is to lay a solid foundation for the subsequent seismic performance of the drill string pile.Through the design and implementation of the aseismic model test of drilling and pipe pile,the following results and rules are obtained:(1)Tests show that the boundary effect of the circular layered shear box designed in this experiment is relatively small,and the boundary will not reflect and scatter the seismic waves under the constraint of the soil mass within the box.The grouting system designed in this experiment can well simulate the construction process of DPC pipe piles.(2)With the increase of vibration intensity,the natural vibration frequency of the soil decreases and the damping ratio increases.(3)From the bottom to the top of the soil around the pile,gradually filter out the high frequency away from the natural frequency of the soil,and turn into a single peak close to the frequency of natural vibration of the soil,indicating that the soil has a filtering effect.(4)With the increase of the peak acceleration of the input seismic wave,the peak amplification factor of the pile bottom acceleration gradually increases.From the shock-absorbing effect to the non-vibration-reducing effect,the acceleration peak amplification factor of the sand layer to the pile cap gradually decreases.