Daosheng Ling

Field Tests on Pile-Supported Embankments over Soft Ground

When designing embankments over soft soils, geotechnical engineers face many challenges. These include potential bearing failure, intolerable settlement, and global or local instability. Pile-supported embankments have been emerged as an effective alternative successfully adopted worldwide to solve these problems. This paper focuses on three cases in which pile-supported embankments were used for constructing highways in the eastern coastal region of China. Each case provides a description of the soil profile, construction procedure, and field monitoring of the settlements, earth pressures, and pore-water pressures. Field monitored data from contact pressures acting on the piles and the soils, to the settlements of the piles and the soils are reported and discussed. The development of the earth pressures both on the piles and the soils shows that there was a significant soil arching in the embankment, and the measured earth pressures acting on the piles are much higher than that acting on the soils betwee...

ANALYTICAL SOLUTION OF A PYROELECTRIC HOLLOW CYLINDER FOR PIEZOTHERMOELASTIC AXISYMMETRIC DYNAMIC PROBLEMS

By virtue of the separation of variables technique, the piezothermoelastic axisymmetric dynamic problem of a pyroelectric hollow cylinder is transformed to a second kind of Volterra integral equation about a function with respect to time, which can be solved successfully by means of the interpolation method. Then the solution of displacements, stresses, electric displacements, and electric potential are obtained. The present method is suitable for a pyroelectric hollow cylinder with an arbitrary thickness subjected to arbitrary thermal loads. Numerical results are presented.

An Experimental Study on a Culvert Buried in Granular Soil Subjected to Vehicle Loads

To understand the performance of culverts buried in the granular soil under heavy vehicle loads, both experimental and numerical studies are conducted. Full-scale model tests with tire loads applied at different locations are carried out to obtain experimental data, and numerical simulation using 3D finite element method is performed to predict the culvert responses and soil distribution due to the same load distribution. Comparisons of the model test results with the computed responses are made in terms of soil pressure above the culvert crown, culvert structures strain, and culvert deflection. The model test results indicate that the buried concrete culverts embedded with compacted aggregate perform good behavior without structural distress. Both numerical analyses and model tests show that the vehicle loads transferred to culvert crown decrease rapidly with the thickness of fill over the culvert. Based on the model tests and numerical analyses, the cover depth of 1.0 m at least is suggested for prefabricated concrete culverts.

Effects of Inhomogeneous Subgrade Settlement to Aircraft Vibration and Its Control Standard

The runway in mountainous areas usually passes across different geological unit and has the form of filled and excavated subgrade. It is of great significance to study the effect of the runway settlement to aircraft vibration. An airplane taxiing model of six degree of freedom which can consider the effect of aerodynamic lift was established to research the influence of settlement amplitude, wavelength and taxiing velocity to aircraft vibration under typical settlement model of inhomogeneous subgrade. The results show that the impact coefficient for posterior main landing gear tire force and root mean square of weighed centroid acceleration increase linearly with the increase of settlement amplitude. Both values have the increasing tendency with the taxiing velocity increasing or the wavelength decreasing. Based on security and passenger comfort, the settlement control standard for inhomogeneous subgrade was proposed. The calculated results can have a positive significance to the settlement control or maintenance of runway in mountainous areas.