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This paper presents an analytical solution for the analysis of axially-loaded compressible floating piles embedded in a homogeneous elastic soil layer of finite thickness. The mathematical model is based on a Tajimi-type elastic continuum formulation, that allows deriving an accurate closed-form expression for the frictional stresses developing at the soil-pile interface. The pile and its underlying soil column are considered as one-dimensional axially deforming rods, and solution of their governing equations leads to closed-form expressions for pile and soil displacements and stresses. The proposed model provides results of similar accuracy to boundary integral solutions for the special case of floating piles in elastic half-space, and to numerical analyses for the general problem of floating piles embedded in a layer of finite thickness. As such, the model is used to prepare charts for the settlement analysis of floating piles in practice, based on a parametric analysis that unveils the sensitivity of the axial response of floating piles to the different problem parameters. [ABSTRACT FROM AUTHOR]

Numerical back analysis based on incomplete in situ stress measurements is widely used to estimate the three-dimensional (3D) in situ stress fields of large deep underground caverns. However, the variable collinearity caused by complex geological environments has rarely been considered. This paper proposes a numerical back analysis method for 3D in situ stress fields based on stepwise regression (BSSR). In BSSR, the collinearity between independent variables is associated with the surface topography, and insignificant variables caused by variable collinearity are eliminated through stepwise regression. BSSR was applied to the underground powerhouse of a hydropower station for validation, and the results showed that it can reliably estimate the 3D in situ stress field despite the complex geological environments. Multidimensional mathematical models of in situ stress fields were established with the improved predictive ability and clear physical meaning, which can quantify the contributions of six geological actions and three stress sources. The findings of this study can help with understanding the formation mechanism of in situ stress fields for large, deep underground caverns in complex geological environments and provide a useful reference for optimizing excavation schemes and support designs. [ABSTRACT FROM AUTHOR]

This paper introduces the principle of Ingested Debris Monitoring System in aero-engine and establishes a mathematical model of its core component, the ring-like probe; this paper simulates foreign object's movement based on the established model and performs numerical analysis of the induced charge pulse waveform. Pulse amplitude and pulse width are used as the two pulse features of pulse waveform. Numerical analysis gets the relationship between pulse features and foreign object's charge amount, velocity and radial position. A new method for estimating foreign object's radial position and charge amount has been proposed based on the conclusion of numerical analysis. Both the correctness of numerical analysis and the new estimating method has been verified in the oil calibration test rig. All the relative errors are within 10%. Further experiments with high velocity condition are carried out in an air-gun test rig. The occurrence time, radial position, charge amount, velocity and material category of foreign object can all be obtained, which has important significance to the safety of aero-engines. [ABSTRACT FROM AUTHOR]