排序方式： 共有32条查询结果，搜索用时 15 毫秒
31.
Semih S. Tezcan Ali Keceli Zuhal Ozdemir 《Geotechnical and Geological Engineering》2006,24(1):203-218
Firstly, the historical background is presented for the determination of ultimate bearing capacity of shallow foundations.
The principles of plastic equilibrium used in the classical formulation of the ultimate bearing capacity are reviewed, followed
by a discussion about the sources of approximations inherent in the classical theory. Secondly, based on a variety of case
histories of site investigations, including extensive bore hole data, laboratory testing and geophysical prospecting, an empirical
formulation is proposed for the determination of allowable bearing capacity of shallow foundations. The proposed expression
corroborates consistently with the results of the classical theory and is proven to be reliable and safe, also from the view
point of maximum allowable settlements. It consists of only two soil parameters, namely, the in-situ measured shear wave velocity, and the unit weight. The unit weight may be also determined with sufficient accuracy, by means
of another empirical expression, using the P-wave velocity. It is indicated that once the shear and P-wave velocities are
measured in-situ by an appropriate geophysical survey, the allowable bearing capacity is determined reliably through a single step operation.
Such an approach, is considerably cost and time-saving, in practice. 相似文献
32.
Hydrological models have been widely used for water resources management. Successful application of hydrological models depends on careful calibration and uncertainty analysis. Spatial unit of water balance calculations may differ widely in different models from grids to hydrological response units (HRU). The Soil and Water Assessment Tool (SWAT) software uses HRU as the spatial unit. SWAT simulates hydrological processes at sub-basin level by deriving HRUs by thresholding areas of soil type, land use, and slope combinations. This may ignore some important areas, which may have great impact on hydrological processes in the watershed. In this study, a hierarchical HRU approach was developed in order to increase model performance and reduce computational complexity simultaneously. For hierarchical optimization, HRUs are first divided into two-HRU types and are optimized with respect to some relevant influence parameters. Then, each HRU is further divided into two. Each child HRU inherits the optimum parameter values of the parent HRU as its initial value. This approach decreases the total calibration time while obtaining a better result. The performance of the hierarchical methodology is demonstrated on two basins, namely Sarisu-Eylikler and Namazgah Dam Lake Basins in Turkey. In Sarisu-Eylikler, we obtained good results by a combination of curve number (CN2), soil hydraulic conductivity, and slope for generating HRUs, while in Namazgah use of only CN2 gave better results. 相似文献