Longzhu Chen

Torsional vibrations of elastic foundation on saturated media

A comprehensive analytical solution is developed to examine the torsional vibration of an elastic foundation on a semi-infinite saturated elastic medium for the first time. First, the governing equations of saturated media are solved by use of Hankel transform techniques. Then, based on the assumption that the contact between the foundation and the half-space is perfectly bonded, this dynamic mixed boundary-value problem can lead to dual integral equations, which are further reduced to the standard Fredholm integral equations of the second kind and solved by numerical procedures. Numerical examples are given at the end of the paper. The numerical results indicate that the response of the elastic foundation strongly depends on the material and geometrical properties of both the saturated soil-foundation system and the load acting on the foundation. In most of the cases, the dynamic behavior of an elastic foundation on saturated media significantly differs from that of a rigid plate bearing on the elastic half-space.

Experimental Study of Effect of Fly Ash on Self-Compacting Rammed Earth Construction Stabilized with Cement-Based Composites

AbstractAs an environmentally friendly construction technique, modern rammed earth generally stabilized with portland cement has attracted growing interest recently. In this study, cement-based composites (CSCN) consisting of cement, sodium silicate, and composite promoter were used for substituting portland cement, and the effect of fly ash was investigated by unconfined compressive strength (UCS) test, thermogravimetric analysis (TG), X-ray diffraction (XRD), and scanning electron microscope (SEM). Based on the theory of pozzolanic and dispersing (P&D) effects, the contribution of fly ash was regarded as an addition of CSCN, and the quantitative analysis of P&D effects defined as P&D factors was evaluated by the clay-water/CSCN ratio hypothesis. It was found that the P&D factors for both compressive strength and secant modulus varied with CSCN content and curing age. The models of different curing ages for predicting the strength and modulus of specimens stabilized with CSCN and fly ash were developed f...