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CONTENTS
Volume 9, Number 2, August 2015
 

Abstract
This paper presents the probabilistic seismic microzonation of densely populated Kolkata city, situated on the world

Key Words
seismic microzonation of Kolkata city; probabilistic seismic hazard; ground motion amplification; response spectra

Address
(1) Amit Shiuly:
Department of Civil Engineering, Jalpaiguri Govt Engg College, 735102, India;
(2) R.B. Sahu, Saroj Mandal:
Department of Civil Engineering, Jadavpur University, Kolkata 32, India.

Abstract
Digital simulation has recently become the preferred method for designing complex and dynamic systems. Simulation packages provide interactive, block-diagram environment for modeling and simulating dynamic models. The block diagrams in simulation models are flowcharts which describe the components of dynamic systems and their interaction. This paper is the first part of the study for determining the seismic behavior of soil systems. The aim of this part is to present the constructed block diagrams for discrete-time analysis of seismic site amplification in layered media for vertically propagating shear waves. Detailed block diagrams are constructed for single and multiple soil layers by considering wave propagation with and without damping, respectively. The block diagrams for recursive filter to model attenuation in discrete-time form are also constructed. Finite difference method is used for strain calculation. The block diagrams are developed by utilizing Simulink which is a software add-on to Matlab.

Key Words
seismic site amplification; soil dynamics; digital simulation; simulink; matlab

Address
Department of Civil Engineering, Yıldız Technical University, 34220, Istanbul, Turkey.

Abstract
This paper is the second part of the study for determining the seismic behavior of soil systems. The aim of this part is to present solution approaches for determining seismic site amplification. For this purpose, two solution techniques are used. The first technique is equivalent linear analysis which is mostly used in literature. The other technique is real time parameter updating approach and this approach uses the possibilities of Simulink effectively. A graphical user interfaced (GUI) program called DTASSA standing for Discrete-Time Analysis of Seismic Site Amplification is developed. In DTASSA, automatic block diagram producing system is developed and seismic site amplification for multiple soil layers may easily be investigated in real time. Numerical applications have been carried out to check the reliability of developed algorithm. The reults of DTASSA are compared with SUA, EERA and NERA programs for the particular example problems.

Key Words
seismic site amplification; soil dynamics; digital simulation; Simulink; Matlab

Address
Department of Civil Engineering, Yıldız Technical University, 34220, Istanbul, Turkey.

Abstract
Barricade failures generally occur at the early times of paste backfill when it is fresh in the stopes. The backfill strength increases and need for barricading pressure decreases as a result of the hydration reactions. In this study, paste backfill barricades of Cayeli copper mine were investigated to design cemented mineral processing plant tailings as barricade body concrete. Paste backfill in sub-level caving stopes of the mine needs to be barricaded for only four or five days. Therefore, short term strength and workability tests were applied on several cemented tailings material designs. Barricade failure mechanisms, important points of barricade designing and details of the new concrete material are explained in this work. According to the results obtained with this experimental study, the tailings were assessed to be used in concrete applied as temporary supports such as cemented paste backfill barricades.

Key Words
paste backfill; barricade support; shotcrete; mining; underground support; sub-level caving

Address
Karadeniz Technical University Mining Engineering Department, Trabzon, Turkey.

Abstract
In this paper, forming of fully clamped circular plate by using low velocity impact system has been investigated. This system consists of liquid shock tube and gravity drop hammer. A series of test on mild steel and aluminum alloy plates has been done. The effect of varying both impact load and the plate material on the deflection are described. This paper also presents a simple model to prediction of mid-point deflection of circular plate by using input-output experimental data. In this way, singular value decomposition (SVD) method is used in conjunction with dimensionless number incorporated in such complex process. The results of obtained model have very good agreement with experimental data and it provides a way of studying and understanding the plastic deformation of impact loads.

Key Words
circular plate; deformation; impact; low velocity

Address
Department of Mechanical Engineering, Faculty of Engineering, University of Guilan, Rasht PO BOX 3756-41635, Iran.


Abstract
In this paper, a series of repeated load tests were carried out on a 150 mm diameter plate simulative of vehicle passes, to demonstrate the benefits of soil-rubber shred mixture in decreasing the soil surface settlement of road embankment. The results show that the efficiency of rubber reinforcement is significantly a function of the rubber content, thickness of rubber-soil mixture and soil cap thickness over the mixture. Minimum surface settlement is provided by 2.5% of rubber in rubber-soil mixture, the thickness of mixture layer and soil cap of 0.5 times the loading surface diameter, giving values of 0.32-0.68 times those obtained in the unreinforced system for low and high values of amplitude of repeated load. In this installation, in contrast with unreinforced bed that shows unstable response, the rate of enhancement in settlement decreases significantly as the number of loading cycles increase and system behaves resiliently without undergoing plastic deformation. The findings encourage the use of rubber shreds obtained from non-reusable tires as a viable material in road works.

Key Words
rubber-soil mixture; soil cap layer; rubber content; settlement; repeated load; road embankment

Address
(1) S.N. Moghaddas Tafreshi:
Department of Civil Engineering, K.N. Toosi University of Technology, Valiasr St., Mirdamad Cr., Tehran, Iran;
(2) A.H. Norouzi:
Department of Civil, Construction and Environmental Engineering, North Carolina State University, USA.

Abstract
Comparative study has been performed to investigate the behavior of dredged fills on rigid (Model 1) and flexible (Model 2) containers. The study was focused on the sedimentation of soil fills and the development of total stresses. Model 1 is made of an acrylic cylinder and Model two is a scale-size geotextile tube. Results indicate that for rigid containers, significant decrease of the sediment height is apparent during the dewatering process. On the other hand, because the geotextile is permeable, the water is gradually dissipated during the filling process on flexible containers. Hence, significant loss in the tube height is not apparent during the duration of the test. Pressure spikes are apparent on rigid containers during the filling process which can be attributed to the confining effect due to hydrostatic pressure. For the flexible containers, the pressure readings gradually increases with time during the filling process and normalize at the end on the filling stage. No pressure spikes were apparent due to the gradual dissipation of pore water pressure.

Key Words
rigid container; flexible container; total stress; geotextile strain; model test

Address
(1) Hyeong-Joo Kim, Myoung-Soo Won:
Department of Civil Engineering, Kunsan National University, Gunsan 573-701, Republic of Korea;
(2) Jang-Baek Lee, Jong-Hoon Joo, Jay C. Jamin:
School of Civil and Environmental Engineering, Kunsan National University, Gunsan 573-701, Republic of Korea.

Abstract
In the present investigation, a series of laboratory compaction and unconfined compressive strength laboratory tests has been performed. To determine the effect of compaction energy, type of sand, and fly ash content, compaction tests have been performed with varying compaction energy (2700 kJ/m3- 300 kJ/m3), types of sand, and fly ash content (0% to 40%) respectively. From the experimental results, it has been found that the optimum value of unconfined compressive strength obtained for a sand-fly ash mixture comprised of 65% sand and 35% fly ash. Based on the data obtained in the present investigation, a linear mathematical model has been developed to predict the OMC of sand-fly ash mixture.

Key Words
compaction; sand; UCS; fly ash; OMC; MDD

Address
Department of Civil Engineering, IIEST, Shibpur, Howrah-711 103, India.


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