Zhang Xuefu

Nonlinear analysis for the three-dimensional temperature fields in cold region tunnels

In this paper, based on the governing differential equations of the problem on temperature field with phase change, the finite element formulae of three-dimensional temperature fields are obtained from Galerkins method. An illustrative example of the three-dimensional temperature fields in cold regions tunnel both with insulation and without insulation is presented on the basis of the air temperatures surveyed in the inside of the tunnel. The example shows that it is necessary to analyze the three-dimensional temperature fields in cold regions tunnels, and that it is effective to lessen the frozen or thawed areas of the rock surrounding the tunnels by constructing insulation, which can provide reference and numerical method for actual engineering design in cold regions.

NONLINEAR ANALYSIS FOR FROST-HEAVING FORCE OF LAND BRIDGES ON QING-TIBET RAILWAY IN COLD REGIONS

ABSTRACT A mathematical mechanical model and the governing differential equations of the coupled problem of temperature, moisture migrating, and stress fields with phase change, are first derived from the theory of heat transfer, the theory of moisture migration, and frozen soil mechanics. Then the finite element formulas of this problem are obtained by using Galerkins method. Using the finite element formulas, a nonlinear analysis for the frost-heaving process of the land bridge in the next 20 years is made. The calculated results show that only soil at the bottom of the pile generates plastic deformation, and the deformation is quite small; therefore, the studied land bridge is safe.