Chang'an University

About: Chang'an University is a education organization based out in Xi'an, China. It is known for research contribution in the topics: Asphalt & Groundwater. The organization has 18415 authors who have published 15102 publications receiving 125436 citations. The organization is also known as: Cháng'ān Dàxué & Changan University.

Prediction of soil deformation in tunnelling using artificial neural networks

Abstract: In the past few decades, as a new tool for analysis of the tough geotechnical problems, artificial neural networks (ANNs) have been successfully applied to address a number of engineering problems, including deformation due to tunnelling in various types of rock mass. Unlike the classical regression methods in which a certain form for the approximation function must be presumed, ANNs do not require the complex constitutive models. Additionally, it is traced that the ANN prediction system is one of the most effective ways to predict the rock mass deformation. Furthermore, it could be envisaged that ANNs would be more feasible for the dynamic prediction of displacements in tunnelling in the future, especially if ANN models are combined with other research methods. In this paper, we summarized the state-of-the-art and future research challenges of ANNs on the tunnel deformation prediction. And the application cases as well as the improvement of ANN models were also presented. The presented ANN models can serve as a benchmark for effective prediction of the tunnel deformation with characters of nonlinearity, high parallelism, fault tolerance, learning, and generalization capability.

Interaction mechanism of cement and asphalt emulsion in asphalt emulsion mixtures

Abstract: The interaction characteristics of cement asphalt composite mastic (CAM) and performance properties of cement asphalt emulsion mixtures (CAEM) were evaluated in this work using chemical and mechanical test methods to investigate the effect of the presence of cement on asphalt emulsion mixtures (AEM). The chemical composition of the CAM was obtained through use of X-ray diffraction, Fourier-transform infrared spectroscopy, and environmental scanning electron microscopy (ESEM) as a means to describe the interactions between the cement and asphalt in the composite materials. Test results demonstrated that cement can hydrate with the water phase of the asphalt emulsion. Asphalt droplets can simultaneously enclose cement particles and delay the hydration reaction process of cement. The interaction mechanism of cement particles or hydration products and residual asphalt is a physical compound process. The influence of these findings on asphalt emulsion mixture design and performance properties was assessed using varying mix design components and conducting laboratory-based mechanical test methods for rutting resistance and moisture susceptibility. Mix design components varied including added water content, emulsion content, and cement dosage levels. The optimum fluids content was determined based on the dry indirect tensile strength. It was found that the cement content significantly impacts the optimum fluids content for both added water and emulsion. Furthermore, the presence of cement improves the dry tensile strength, rutting resistance, and moisture susceptibility. Based on microstructural analysis of CAM and CAEM, the mechanism by which cement improves the performance of AEM is attributed to the ability of hydration products to increase both the stiffness of the asphalt binder and the adhesion at the mastic–aggregate interface. In practical applications, this study recommends a mix design method for cement-modified asphalt emulsion mixes (CAEM) based on selection of optimum cement and emulsion contents using indirect tensile strength and verification of the design through evaluation of the moisture susceptibility and rutting resistance of the CAEM mix. Threshold values of CAEM mix mechanical properties to determine the quality of the design are proposed.

Experimental Investigation on Rehabilitation of Corroded RC Columns with BSP and HPFL under Combined Loadings

Abstract: This research focuses on evaluating the seismic properties of corrosion-damaged RC columns strengthened by bonded steel plate (BSP) and high-performance ferrocement laminate (HPFL). The mec...