Study On Engineering Behavior Of Reinforced Concrete Wrapped Pile Geotextile Bag In Saline Soil Area

In the saline soil distribution area of Northwest China,reinforced concrete in the foundation has been subjected to severe corrosion damage under the superimposition of many unfavorable factors,such as building load,unfavorable geological environment and so on.At present,the understanding of corrosion prevention of reinforced concrete foundation is not mature enough,and it is still in the stage of continuous analysis and research.With the help of Hami South-Zhengzhou DC Line Pile Foundation Project,this paper conducts field test and analysis of large diameter reinforced concrete wrapped cast-in-place piles.The purpose is to solve some problems existing in the optimization of material and technology for making anti-corrosion bags and the efficiency of lowering and installing them,so as to make reinforced concrete wrapped piles more widely popularized and applied.In this paper,according to the design concept of the new technology patent"Anti-corrosive reinforced concrete wrapped pile applied in saline soil foundation",starting with the anti-corrosive bag material of the pile body which interrupts the corrosive deterioration molecule contact,the material is selected in a variety of Geotextiles and geomembranes with relatively reasonable cost.The anti-corrosion and anti-seepage performance meets the requirements of the specifications through the test,and the WJF-1 polypropylene is finally selected.Polypropylene filament woven geotextiles and HDPE anti-seepage geotextile film are used to form composite geotextiles by "two cloths and one film" hot rolling process,and then processed into special anti-corrosion bags,which can not only meet the design requirements for anti-corrosion of pile foundation,but also save the cost of construction.Through the study of the technology of installing anti-corrosion geotextile bags on site,starting with the mechanical model of grout used in the grouting displacement method and the mechanism of the grouting displacement method,the theoretical basis of the grouting displacement method is found,and the technical parameters required for construction are further standardized scientifically.Through analysis and research,it is found that the main factors affecting the effectiveness of anti-corrosive geotextile bags installation are buoyancy and piston effect.The construction parameters of injection-displacement replacement method and the technical parameters of the bottom counterweight of bags are improved,and the field test and analysis of the improvement effect is carried out to improve the construction efficiency of anti-corrosive Geotextile bags installation.Through on-site testing and analysis of pile bearing capacity,experimental research and summary are carried out from two aspects of pile side and pile end resistance.The main factors affecting pile bearing capacity,such as pull-down load caused by negative friction,liquefaction of sand,size effect and friction resistance of soil distribution,are found,and one by one analysis is made.Suggestions are put forward to revise the standard value formula of pile bearing capacity.The theoretical calculation value is more in line with the site engineering geological conditions,and some auxiliary analysis work is done for the application and popularization of large diameter reinforced concrete wrapped cast-in-place piles in future engineering projects.