Preload-bearing Compression Technology Research Upon Shanghai International Formula One Circuit

Shanghai International Formula 1 Circuit tracks are the unique and unparalleled high-leveled racing ones within the same F1 tracks of the world, which built on the soft foundation, Yangtze River Delta, through the way of filling layer by layer. When mention the engineering of Fl tracks, 3mm/4m error is the important safety guideline to the evenness of Fl tracks, in addition, the high-levelled tracks and strict requirement, and still, the different settlement is the key element which can influence evenness. So, so as to decrease settlement effect and increase loading-bearing capacity of foundation, upon the design requirement, the lager-sized preload-bearing compression will be adopted within the area of tracks, on accordance with the finished station requirements, 2m section and 3m section preload-bearing compression have been taken.On consideration with the tracks engineering characteristics of larger-sized, urgent and hard engineering date, thick soft and weak earthworks layers, strict settlement and different settlement requirements, it is necessary to research concretion degree, settlement development changed regulation and effect element of weak and soft clay foundation, conclude and accumulate large-scale engineering experience under the condition of large-scaled preload-bearing compression;to research concretion and settlement process with the change of time at the area of preload-bearing compression, and as well as the sectional distribution characteristics for the purpose of guiding and direction for engineering.The followings are some conclusion made from this thesis:(1) through the layer of this ground condition, 9m ahead belongs to good permeable stratum layer of No.②-1 No.②-2a, ②-3, and hole water pressure releasing quickly, which composingthe important part of settlement happening on the earlier period of preload-bearing compression;middle layer group, No.? and No.? -la compose the important part that happening on the final period of settlement due to deep burying, bad penetrability, worse drainage condition and high compressibility, and still, featured with long concretion time and large settlement ability;layer No. (D-lb is featured with less settlement ability because of earth characteristics and bury/ hiding condition.(2)foundation earthworks has obviously occurred plasticity diversity due to uneven load-bearing and larger settlement factors at the partial area, which should be aroused the enough attention of contractor and the client, the necessary making-up measures should be taken to reinforce the foundation in the final period to avoid the continuous large-sized settlement.(3)area of common boundary between partial pile-striven area and load-bearing area have obviously appeared uneven settlement, so, the necessary measures should be done to avoid the different settlement.(4) on condition of works finished, if the load is 30kPa, then the estimate track foundation settlement should be within 30cm, presently, compare to preload-bearing compression foundation earthworks and earthworks filling load, the average value of collectivity concretion should be within 20%--30%, compared to the load after works completed, the collectivity average concretion value should be within 60%--70%, it is estimate that under the present engineering schedule, settlement after works completed should be within 15—20cm and settlement stability date should be within 5-8 years or so.(5) during the present process of load excavating engineering, excavating speed and load-bearing speed should be strictly controlled to avoid intention decreasing due to foundation earthworks having been influenced badly.