| With the rapid development of national economy, airports construction and extension are stepping into blowout times, accompanying with more and more high fill projects in mountainous areas. Topography fluctuation, large quantities of digging and fill, complex hydrogeology conditions and susceptible water level variation with the seasons, these are the common conditions of the mountainous high fill projects. Under rainfall or groundwater seepage, slaking settlement would occur to the wetting filler. It remains to be an important issue that how to evaluate the settlement and differential settlement law under wetting condition, satisfying settlement and differential settlement demands of projects during the construction and after the construction. This dissertation employed FLAC3 D Software combined with field test and long-term stratified monitoring in engineering site to study the enlargement of settlement and differential settlement under wetting condition compared with natural condition. The main research contents and results are as follows:① The slaking deformation mechanism of soil-aggregate mixture and its influencing factors are analyzed. By means of single ring injection test, permeability coefficient of the filler in research area is obtained. Through field trench excavation test, the law of water content variation in vertical direction along the profile is studied. According to empirical formula, influence depth of soil-aggregate mixture under rainfall infiltration is achieved.②Through stratified monitoring of filler at engineering site, some results are obtained, maximum settlement during loading construction is 43.09 cm while the settlement rate is 0.71~2.56mm/d, when loading completed, the value is 0.13~0.32mm/d. Settlement rate and settlement appear a positive relationship with filler height and filling rate. The water content formula varies with the soil depth is y=-0.0484x2-0.1781x+10.468, settlement rate enlarges to some extent as the water content increases.③By the Auto CAD—ANSYS—FLAC3D combination method, 3D simulation model of complex topography is built. According to the analysis, maximum settlement at X and Y direction is found at the slope position, and the more steeper of slope, the higher value of the settlement. However, settlement at Z direction is mainly controlled by filler height, maximum settlement, 52.93 cm, is found at 29.8m, top of the filler. The maximum settlement rate and the average differential settlement is 11.42‰ and 3.41‰. Three wetting conditions are chosen, slaking influence depth under rainfall, 5m, 10 m, 20 m, while in these conditions, water levels rising 1m, 3m, 5m, the maximum deformations enlarge 3.5%, 12%, 20% correspondingly compared with natural condition. The increasing slaking depth unfolds greater effect on settlement than water level rising, which is validated by site monitoring results.④Based on multivariate orthogonal range analysis, parameter sensitivity of the factors that affecting filler settlement is analyzed, the sorting sequencing is that, deformation modulus E0 > density r >cohesion c>frictionj >poisson ratio μ. Geotechnical parameters are back analyzed according to existing monitoring data, then the back-calculated parameters are substituted into models to analyze the remain monitoring points, the results show that the back-analysis parameters are reasonable. |
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