Ren Qingwen

Research advance in safety analysis methods for high concrete dam

High tensile stresses occurred in high concrete dams and in their foundation lead to the growing importance of their safety with the increase of concrete dam height. Without any exiting specification or successful experiences of concrete dams up to 300 m at home and abroad for reference, experts feel obliged to figure out how to perform safety analysis on high concrete dam. This paper involves the main contents and mechanical features of the safety analysis on high concrete dam and shows the current state and progress of the analysis methods. For the insufficiency and problems existing in normative methods, study on modern numerical method such as finite element method must be strengthened to find out the stress control criterion which is in accordance with the methods. Two aspects of the safety analysis of high dam—local damage from material level and integral destruction from structure level—should be considered. For the local damage, we should consider the non-homogeneity of material and strengthen the research of meso-damage mechanics. While for integral destruction of the system of high dam and its foundation, a study on non-strength theory should receive enough concerns. Further, attention should be paid to the research on the failure modes and criterions of high concrete dam failure analysis and safety evaluation, and the effect of uncertainty and classification of safety should be considered too.

Time rates of Hill's strain tensors

Based on Hills principal components formulae, two kinds of basis-free time rate formulae for Hills strain tensors are proposed in this paper, which are obtained for the cases of distinct stretches, double coalescence and triple coalescence. Furthermore, relations between the coefficients in the representation for the strain tensor and its time derivative are disclosed.

A study of mechanical behavior of rock-fill materials with reference to particle crushing

In rock-fill dams of 200 to 300 m high, maximum compressive stress can exceed 6 MPa. At such a high stress level, rock-fill materials may experience particle crushing during shear. The material behavior is highly sophisticated exhibiting pressure and density dependency as well as particle crushing effects. Through scrutinizing the relevant experimental data on rock-fill materials and sands published in the literatures, this paper is focused on understanding basic mechanical characteristics of this sort of materials in the light of constitutive modelling.

Analysis of the Stability Along its Base Surface of High Arch Dam

ABSTRACT The stability of arch dam along its base surface is a problem to which dam engineers have paid close attention in recent years. So far there haven’t been comparatively accordant opinions about the possibility and mechanism of the failure of arch dams along its base surface or any good methods which can determine the safety degree of the stability. This paper presents the deformed-body method of analyzing the stability and the convergence and abrupt change criterion of stability. The degree of stability of Xiaowan arch dam along the base surface is studied by the finite element analysis.