Study On The Technique Of Sand And Gravel Pile In The Treatment Of Soft Foundation

In the process of highway construction,the distribution of soft foundation is common,soft foundation has the characteristics of high compressibility,greater sensitivity,poor permeability and low bearing capacity of soil,etc.Therefore,in the foundation treatment,the reinforcement of bearing layer is particularly important.The soft foundation treatment technology of vibroflotation gravel pile can make full use of the abundant sand and stone resources around the site,facilitate the local materials,reduce the use of cement and steel,and reduce the cost of packing to a certain extent.The vibroflotation method has the advantages of fast construction speed,easy control of the precision of pile length and distance,stable quality of pile and obvious reinforcement effect for complex foundation.This method not only plays the role of drainage consolidation and soil stability in the process of soft foundation treatment,but also has significant effects on increasing the compressive strength of soil,vertical shear strength and reducing horizontal and vertical displacement.It is a safe,economic and reasonable construction technology method for strengthening soft foundation.In this paper,based on the soft soil foundation of K75+ 225-k75 +425 under the construction of xintai expressway,the soil quality of the soft foundation is analyzed,and the finite element software ABAQUS is used to carry out numerical simulation calculation on the composite foundation of sand and gravel piles under different working conditions.Combined with the field test,the reinforcement effect and influence rule of vibroflotation sand and gravel piles are compared and analyzed.The specific research content is as follows:(1)On the premise of extensively consulting the existing literature on the treatment of soft foundation by vibroflotation sand and gravel piles,the working mechanism,reinforcement method and construction process of the technology are described in detail,and the equipment model,applicable soil quality and construction requirements of the vibroflot are briefly summarized.(2)Based on the finite element software ABAQUS,modeling of undisturbed soil and gravel pile composite foundation analysis,by comparing the gravel pile and the vertical displacement,and the size of the bearing capacity of composite foundation,explore the strengthening effect of gravel pile,and combined with the light dynamic penetration test and single pile static load test to validate the results of numerical simulation.(3)Under the condition of traffic load,various working conditions such as with or without geogrids,different pile compressive modulus,different pile lengths and different pile diameters are modeled and calculated respectively.Through comparative analysis,the influence rules of each working condition on composite foundation are studied,and the optimal design parameters of sand and gravel pile are selected.