Vol 53, No 2 (2016)

Nonlinear relations based on Winkler-like and Coulomb laws are proposed to describe the process of shear interaction between structures and soil. Their advantages and shortcomings are illustrated, along with the suitability of experimental results.

To study the collapse characteristics of high-density silt under complex loads, three series of hollow-cylinder tests were conducted on high-density saturated silt samples taken from the sea entrance of the Yangtze River. In the first series of tests, samples with high density were isotropically consolidated and then sheared under undrained triaxial loads. In subsequent tests, samples with low and high densities were isotropically consolidated and then cyclically sheared by principal stress rotation of 0-180°. Collapse and liquefaction were clearly observed in all the samples tested under cyclic principal stress rotation when the pore water pressure was equal to the initial effective confining pressure. Two critical points, the graded phase transformation point and the cataclysmic phase transformation point (collapse point), were observed for the high-density samples before liquefaction; these divided the buildup of the pore water pressure into three or two stages depending the shear stress level. At low shear stresses, the characteristics of the transformation points were hardly influenced by load frequency. The isotropic consolidated high-density silt and low-density silt expressed similar behaviors. However, in the high-density silt, the strain development could be divided into two stages by the collapse point, which corresponds to the cataclysmic phase transformation point of the pore water pressure representing the state of structure collapse. The deviator strains were limited within a narrow range of 0.2-0.4% at the collapse state. The stress state of collapse can be normalized by the quasi-unstable line in the p'-q space. Finally, we introduce the modified Seed model to successfully estimate the development of pore water pressure in high-density silt.

The standard penetration test (SPT) and Menard’s pressuremeter test (PMT) are among the available in-situ techniques. This research has been carried out with the aim to develop correlations among the in-situ parameters obtained by both methods.

Many unstable slopes are extensively supported by stabilizing piles. Excavation work, rainfall, and earthquakes can cause lateral soil movement, creating forces that act on the stabilizing piles. We present a new simplified method based on the Winkler elastic model for analyzing the response of flexible piles subjected to lateral soil movement in landslides. The new method can analyze cases in which the movement depth profile of the sliding layer is arbitrary by using a two-stage analysis method. First, the free-field soil movement data of the unstable soil mass are fitted by a polynomial spline using the leastsquares method. Then a system of differential equations for flexible piles subjected to lateral soil movement is presented to describe the behavior of the piles embedded in the slope. The formulation considers the soil-pile interaction to derive the analytical solution via a matrix pattern. Finally, the proposed method is verified by comparing the calculated results with those of three published case studies. The results show a good correlation between the calculated and measured responses of flexible stabilizing piles, verifying the reliability of the proposed analytical solution.

Large coal resources occur under buildings in the Iron Third District of Tangshan Mine, which not only greatly reduces the service life of the coal mine, but also wastes the coal resources. To ensure the safety of ground buildings and maximize exploitation of the coal resources, solid backfill mining technology is proposed. This paper studies the compression ratio of the coal seam during backfill mining with a global numerical model based on the finite difference software, FLAC3D. The compression ratio of the coal seam was also similarly studied based on theoretical analysis and the local model.

The causes are examined for the reduction in bearing capacity and the increase in failure rate of pile foundations in permafrost soil north of the Arctic Circle. Methods of increasing or stabilizing the bearing capacity of pile supports using pile structural solutions and heat stabilizers having diverse action mechanisms.