| In order to solve the problems of regional population concentration and the scarcity of coastal land resources,the coastal areas of China have fully developed the construction of tidal flat projects,made use of the abundant coastal tidal flat resources,and continued to expand available land resources.On the one hand,tidal mud pile foundation mainly bears horizontal loads such as wave load and earthquake load because the working area is close to the offshore sea.On the other hand,due to the characteristics of high water content,high compressibility and low foundation bearing capacity,mudflat silt is not conducive to exerting the bearing capacity of pile foundation.Therefore,it is necessary to adopt appropriate consolidation treatment for mudflat silt before carrying out the construction of pile foundation.In the past literature,the research reports on pile foundation design on mudflat mud foundation are rare,and the relevant data are mostly from the experience estimation of engineering projects.In view of the above problems,this paper adopts the method of combining laboratory test and field test to study the bearing characteristics of single pile foundation before and after vacuum preloading treatment of mudflat silt foundation,so as to provide a scientific criterion for the design of wind turbine pile foundation in practical engineering.The main contents of the study are as follows:(1)Inhouse static load tests under vertical load,static load under horizontal load and cyclic load were carried out according to the similarity criterion to analyze the load-settlement and load-horizontal displacement relations.The results show that the bearing capacity of pile foundation in mudflat mud foundation has been significantly improved after vacuum preloading treatment.After the treatment,the displacement curve of indoor test pile is more gentle,and the ultimate bearing capacity is increased by18.2% compared with that before the vacuum preloading treatment.(2)Field vacuum preloading test was carried out to analyze the physical and mechanical characteristics index data before and after vacuum preloading,as well as the change rule of soil moisture content and shear strength of cross plate.After treatment,the water content decreases by 40%,and the surface settlement of soil reaches 1268 mm,which provides the determination of soil physical and mechanical characteristics parameters for the study of pile foundation bearing capacity.(3)To carry out the single pile foundation vertical bearing characteristic test,indoor simulation test results of on-site validation,vacuum preloading treatment beach silt foundation vertical bearing capacity of pile foundation increased by 25%,the analysis of field test pile axial force distribution of friction resistance of piles increased 1.08 times,the largest vacuum preloading is proved promoted the vertical bearing capacity of pile foundation in all aspects.According to the level of indoor experiments on ultimate bearing capacity,to determine the pile horizontal load loading plan,on-site vacuum preloading pile static load and cyclic horizontal load test before and after processing,it is concluded that the vacuum preloading ultimate bearing capacity of pile foundation increased by 120%,after the bottom horizontal displacement amplitude decreases,and the section points bending moment increases and the maximum bending moment of pile up,the final level of pile foundation bearing performance data.(4)The results show that vacuum preloading can improve the horizontal bearing capacity of pile foundation more effectively.Therefore,foundation treatment is needed for projects with high horizontal bearing capacity,such as wind power projects and sluices. |
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