Vacuum - Heap Load Joint Preload Soft Soil Subgrade Settlement Observation And Prediction

The seventh contract section of the Hang(Hangzhou)—Pu(Pudong in shanghai) expressway was taken as the project background in this article, and the vacuum-mound preloading method was used to strengthen the soft soil subgrade. To the subject in analyzing and predicting for settlements of the soft ground bed, the method which combined with test from the room and live, live monitor and theoretical research ,was studied in system and. depth.The groundwork is as follows:1. After considering geological conditions and design situations of the project comprehensively, the monitor section was chosen rationally and a feasible monitoring scheme was made;2. The law varied with time, the load and the distribution law with depth which based on the monitored data was analyzed to guide the construction smoothly. What was included in the monitored data were the settlements in the earth's surface, settlements in divided layers, the water pressure between holes in the soils, horizontal displacement, vacuum degree, etc.3. The simplified mode for calculation which multiply the coefficient of settlement ms with the main consolidation settlement S_c was used to compute the total settlements. The GAOMUJUNJIE-Method was taken to calculate the average consolidation degree. The result of calculation by theory and the measurement in actual were compared and analyzed to verify the rationality of the computing method and the calculation parameter. The results indicated that: as for the loads on the embankment, the average consolidation degree of every district is between 97% and 99% by April 15, 2006.4. The basic principles and characteristics of the commonly used method for settlement prediction, such as hyperbolic fitting method, the Asaoka method, the exponential curve fitting method; the Poission curve fitting method was analyzed. The practical procedure named FIT.f90 for settlement prediction was compiled in FORTRAN language to forecast the settlement by the four given methods above.5. The monitored data in the program was applied in the procedure FIT.f90 for settlement prediction, and comparative and analysis were made among the predicted results. It is indicated by the application in the program that: the Asaoka method is the most suitable method for settlement forecast.