Abstract
In this paper, a novel fibrous material known as axially reinforced braided composite rods (BCRs) have been developed for reinforcement of soils. These innovative materials consist of an axial reinforcement system, comprised of longitudinally oriented core fibres, which is responsible for mechanical performance and, a braided cover, which gives a ribbed surface texture for better interfacial interactions with soils. BCRs were produced using both thermosetting (unsaturated polyester) and thermoplastic (polypropylene) matrices and synthetic (carbon, glass, HT polyethylene), as well as natural (sisal) core fibres. BCRs were characterized for tensile properties and the influence of core fibres was studied. Moreover, BCRs containing carbon fibre in the core composition were characterized for piezoresistivity and strain sensing properties under flexural deformation. According to the experimental results, the developed braided composites showed tailorable and wide range of mechanical properties, depending on the core fibres and exhibited very good strain sensing behavior.
Address
Raul Fangueiro, Sohel Rana and A. Gomes Correia: Department of Civil Engineering, University of Minho, 4800-058 Guimaraes, Portugal; A. Gomes Correia: CTAC - Territory, Environment and Construction Research Centre, University of Minho, 4800-058 Guimaraes, Portugal; Raul Fangueiro: Center for Textile Science and Technology, University of Minho, 4800-058 Guimaraes, Portugal
Abstract
Construction of the extension project of the Bangkok MRT Blue Line underground railway was recently started in 2011. The construction of approximately 5 km long underground tunnel and 4 deep excavations of underground station are considered to be the most important geotechnical works. The pressuremeter was selected as a high-quality in situ testing of the soil to evaluate design parameters for the project. In addition, other field and laboratory tests such as vane shear and CK0U triaxial tests were included in the investigation programme. This paper aims to present the ground conditions encountered along the MRT Blue Line extension project as well as the site investigation and interpretation techniques with particular focus on the pressuremeter tests. The results are also compared with the pressuremeter investigation from the previous Bangkok MRT project.
Key Words
geotechnical parameters; in situ testing; pressuremeter; mass rapid transit; Bangkok Clay
Address
Suched Likitlersuang: Department of Civil Engineering, Faculty of Engineering, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok 10330, Thailand; Chanaton Surarak, Erwin Oh and Arumugam Balasubramaniam: School of Engineering, Griffith University, Gold Coast Campus, Queensland, Australia; Dariusz Wanatowski: Nottingham Centre for Geomechanics, The University of Nottingham, United Kingdom/Department of Civil Engineering, The University of Nottingham Ningbo, China
Abstract
Pile load tests using Osterberg cells (O-cell) were conducted on cast-in-place concrete piles founded in oil sand fill and in situ oil sand at an industrial plant site in Fort McMurray, Alberta, Canada. Interpreted pile test results show that very high pile shaft resistance (with the Bjerrum-Burland or Beta coefficient of 2.5-4.5) against oil sand could be mobilized at small relative displacements of 2-3% of shaft diameter. Finite element simulations based on linear elastic and elasto-plastic models for oil sand materials were used to analyze the pile load test measurements. Two constitutive models yield comparable top-down load versus pile head displacement curves, but very different behaviour in mobilization of pile shaft and end bearing resistances. The elasto-plastic model produces more consistent matching in both pile shaft and end bearing resistances whereas the linear elastic under- and over-predicts the shaft and end bearing resistances, respectively. The mobilization of high shaft resistance in oil sand under pile load is attributed to the very dense and interlocked structure of oil sand which results in high matrix stiffness, high friction angle, and high shear dilation.
Address
L. Barr: Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Alberta, Canada; R.C.K. Wong: 2Department of Civil Engineering, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
Abstract
Calculation of seismic displacements in reinforced slopes plays a crucial role in appropriate design of these structures however current analytical methods result indifferent values for permanent displacements of the slope. In this paper, based on limit equilibrium and using the horizontal slices method, a new formulation has been proposed for estimating the seismic displacements of a reinforced slope under earthquake records. In this method, failure wedge is divided into a number of horizontal slices. Assuming linear variations for tensile forces of reinforcements along the height of the slope, the coefficient of yield acceleration has been estimated. The simplicity of calculations and taking into account the frequency content of input triggers are among the advantages of the present formulation. Comparison of the results shows that the yield acceleration calculated by the suggested method is very close to the values resulted from other techniques. On the other hand, while there is a significant difference between permanent displacements, the values obtained from the suggested method place somehow between those calculated by the other techniques.
Address
Ali Ghanbari, Abbas Khalilpasha and Babak Heydari: Faculty of Engineering, Kharazmi University, No. 49 Mofatteh Ave., Tehran, I.R. Iran; Mohsen Sabermahani: Faculty of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, I.R. Iran
Abstract
In the present study, the numerical and experimental investigations were performed on the backfill- exterior wall-fluid interaction systems in case of empty and full tanks. For this, firstly, the non-linear three dimensional (3D) finite element models were developed considering both backfill-wall and fluid-wall interactions, and modal analyses for these systems were carried out in order to acquire modal frequencies and mode shapes by means of ANSYS finite element structural analysis program. Secondly, a series of field tests were fulfilled to define their modal characteristics and to compare the results from proposed approximation in the selected structures. Finally, comparing the theoretical predictions from the finite element models to results from experimental measurements, a close agreement was found between theory and experiment. Thus, it can be easily stated that experimental verifications provide strong support for the finite element models and the proposed procedures themselves are the meritorious approximations to the real problem, and this makes the models appealing for use in further investigations.
Key Words
rectangular tank; forced vibration tests; finite element model; fluid-structure-soil interaction
Address
Tufan Cakir: Department of Civil Engineering, Gumuşhane University, 29000 Gumuşhane, Turkey; Ramazan Livaoglu: Department of Civil Engineering, Uludağ University, 16059 Bursa, Turkey
