The Research On Mechanism To Binder Course Subgrade On Differential Settlement Of Loess Area

When the expressway is constructed or widened in loess region, one of the most difficult problems is the treatment of uneven settlement between the new and old embankment. To understand and unveil correctly the characteristic of deformation of the loess due to damp collapse will facilitate the construction of expressway in the damp collapse region both theoretically and practically. Based on the available achievements on the damp collapse loess in the area of Tong Chuan, a new constitutive relation for such loess is put forward. After several tests, such as the compression test of undisturbed loess in door, the collapse test of wet undisturbed loess, the test of remodeling loess and triaxal shear test, the thesis studies the structure of unsaturated loess and its influential factor, and the influence of the loess's structure on its mechanics features. Also based on the test results, the thesis conducts an analysis on the deformation of damp collapse loess, collapse mechanism of unsaturated loess, the collapse distinction between undisturbed loess and disturbed loess, contributing a theoretical base for the research of uneven settlement at the conjunction between the new and old embankment. Now, some work has been done about the regulation of uneven settlement at the conjunction between the new and old embankment. By making use of the model of Mohr-Coulomb and FLAC software, the thesis calculates the settlement curves for the old-new foundation as well as the embankment to which the gravity and external loads are applied. Compared with the results from the practical engineering, the final positions and maximal settlement in different height of embankment are obtained, also a time-dependent formula for calculating the settlement and final value of the settlement is derived.