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CONTENTS
Volume 8, Number 3, March 2015
 

Abstract
In this paper, a new hyperbolic shear deformation plate theory based on neutral surface position is developed for the static analysis of functionally graded plates (FGPs). The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. The neutral surface position for a functionally graded plate which its material properties vary in the thickness direction is determined. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present new hyperbolic shear deformation plate theory and the neutral surface concept, the governing equations of equilibrium are derived from the principle of virtual displacements. Numerical illustrations concern flexural behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

Key Words
mechanical properties; functionally graded material; neutral surface position; shear deformation; volume fraction

Address
(1) M. Merazi, L. Hadji, T.H. Daouadji, Abdelouahed Tounsi, E.A. Adda Bedia:
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(2) L. Hadji, T.H. Daouadji:
Université Ibn Khaldoun, BP 78 Zaaroura, 14000 Tiaret, Algérie.

Abstract
This paper presents an elasto-plastic model for determination of the ground response curve of a circular underwater tunnel excavated in elastic-strain softening rock mass compatible with a nonlinear Hoek-Brown yield criterion. The finite difference method (FDM) was used to propose a new solution to calculate pore water pressure, stress, and strain distributions on periphery of circular tunnels in axisymmetric and plain strain conditions. In the proposed solution, a modified non-radial flow pattern, for the hydraulic analysis, is utilized. To evaluate the effect of gravitational loads and variations of pore water pressure, the equations concerning different directions around the tunnel (crown, wall, and floor) are derived. Regarding the strain-softening behavior of the rock mass, the stepwise method is executed for the plastic zone in which parameters of strength, dilatancy, stresses, strains, and deformation are different from their elasto-plastic boundary values as compared to the tunnel boundary values. Besides, the analytical equations are developed for the elastic zone. The accuracy and application of the proposed method is demonstrated by a number of examples. The results present the effects of seepage body forces, gravitational loads and dilatancy angle on ground response curve appropriately.

Key Words
ground response curve; gravitational loads; seepage; strain-softening behavior; underwater tunnel

Address
(1) Ahmad Fahimifar:
Department of Civil and Environmental Engineering, Amirkabir University of Technology, 424 Hafez Ave, Tehran, Iran;
(2) Hamed Ghadami:
Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran;
(3) Masoud Ahmadvand:
Department of Civil Engineering, Tafresh University, First of Tehran road, Tafresh, Iran.

Abstract
Constructions over soft and loose soils are one of the most frequent problems in many parts of the world. Cement and cement-lime mixture have been widely used for decades to improve the strength of these soils with the deep soil mixing method. In this study, to investigate the freeze-thaw effect of sand improved by polymers (i.e., styrene-acrylic-copolymer-SACP, polyvinyl acetate-PVAc and xanthan gum) and fly ash, unconfined compression tests were performed on specimens which were exposed to freeze-thaw cycles and on specimens which were not exposed to freeze-thaw cycles. The laboratory test results concluded that the unconfined compressive strength increased with the increase of polymer ratio and curing time, whereas, the changes on unconfined compressive strength with increase of freeze-thaw cycles were insignificant. The overall evaluation of results has revealed that polymers containing fly ash is a good promise and potential as a candidate for deep soil mixing application.

Key Words
deep soil mixing; polymer; unconfined compressive strength; sand, freeze-thaw

Address
Department of Civil Engineering, Ataturk University, Erzurum, Turkey.

Abstract
The governing equations of wave propagation in one dimension of elastic continuum materials are investigated by taking the influence of the initial stress into account. After a short review of the theory of elastic wave propagation in a rock mass with an initial stress, results indicate that the initial stress differentially influences P-wave and S-wave propagation. For example, when the initial stress is homogeneous, for the P-wave, the initial stress only affects the magnitude of the elastic coefficients, but for the S-wave, the initial stress not only influences the elastic coefficients but also changes the governing equation of wave propagation. In addition, the P-wave and S-wave velocities were measured for granite samples at a low initial stress state; the results indicate that the seismic velocities increase with the initial stress. The analysis of the previous data of seismic velocities and elastic coefficients in rocks under ultra-high hydrostatic initial stress are also investigated.

Key Words
stress wave; governing equations; initial stress; seismic velocities; elastic coefficients

Address
(1) School of Resources and Safety Engineering, Central South University, Changsha, Hunan, PR, China.
(2) Hunan Key Laboratory of Resources Exploitation and Hazard Control for Deep Metal Mines, Changsha, China.

Abstract
In this paper, stabilities of a plane slide rock slope under different hydraulic distributions were studied based on the nonlinear Barton-Bandis (B-B) failure criterion. The influence of various parameters on the stability of rock slopes was analyzed. Parametric analysis indicated that studying the factor of safety (FS) of planar slide rock slopes using the B-B failure criterion is both simple and effective and that the effects of the basic friction angle of the joint (φb), the joint roughness coefficient (JRC), and the joint compressive strength (JCS) on the FS of a planar slide rock slope are significant. Qualitatively, the influence of the JCS on the FS of a slope is small, whereas the influences of the φb and the JRC are significant. The FS of the rock slope decreases as the water in a tension crack becomes deeper. This trend is more significant when the flow outlet is blocked, a situation that is particularly prevalent in regions with permafrost or seasonal frozen soil. Finally, the work is extended to study the reliability of the slope against plane failure according to the uncertainty from physical and mechanics parameters.

Key Words
rock slope stability analysis; plane failure; nonlinear Barton-Bandis failure criterion; hydraulic action; factor of safety

Address
(1) Lian-Heng Zhao, Jingyuan Cao:
School of Civil Engineering, Central South University, Changsha 410075, China;
(2) Yingbin Zhang:
Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, China;
(3) Yingbin Zhang:
Department of Geotechnical Engineering, School of Civil Engineering, Southwest Jiaotong University, Chengdu 611756, China;
(4) Qiang Luo:
Department of Communications of Guizhou Province, Guizhou Guiyang 550003, China.

Abstract
In the present case study, High Strain Dynamic Testing of piles is conducted at 3 different locations of Kolkata city of India. The raw field data acquired is analyzed using Pile Driving Analyzer (PDA) and CAPWAP (Case Pile Wave Analysis Programme) computer software and load settlement curves along with variation of force and velocity with time is obtained. A finite difference based numerical software FLAC3D has been used for simulating the field conditions by simulating similar soil-pile models for each case. The net pile displacement and ultimate pile capacity determined from the field tests and estimated by using numerical analyses are compared. It is seen that the ultimate capacity of the pile computed using FLAC3D differs from the field test results by around 9%, thereby indicating the efficiency of FLAC3D as reliable numerical software for analyzing pile foundations subjected to impact loading. Moreover, various parameters like top layers of cohesive soil varying from soft to stiff consistency, pile length, pile diameter, pile impedance and critical height of fall of the hammer have been found to influence both pile displacement and net pile capacity substantially. It may, therefore, be suggested to include the test in relevant IS code of practice.

Key Words
FLAC3D; CAPWAP; PDA; displacement; pile capacity; High Strain Dynamic Testing; pile impedance

Address
(1) Kaustav Chatterjee, Deepankar Choudhury:
Department of Civil Engineering, Indian Institute of Technology Bombay, Mumbai, 400076, India;
(2) Vansittee Dilli Rao:
W S Atkins (India) Pvt. Ltd., Bangalore, India and Department of Civil Engineering, Indian Institute of Technology Bombay, Mumbai, 400076, India;
(3) S.P. Mukherjee:
Department of Civil Engineering, Jadavpur University, Kolkata, 700032, India.

Abstract
A new theoretical approach for analysis of stress around a tensioned anchor in rock is presented in this paper. The solution has been derived for semi-infinite elastic rock and anchor and for plane strain conditions. The method considers both the anchor head bearing plate and its grouted bond length embedded in depth. The solution of the tensioned rock anchor problem is obtained by superimposing the solutions of two simpler but fundamental problems: A distributed load applied at a finite portion (bearing plate area) of the rock surface and a distributed shear stress applied at the anchor-rock interface along the bond length. The solution of the first problem already exists and the solution of the shear stress distributed along the bond length is found in this study. To acquire a deep understanding of the stress distribution around a tensioned anchor in rock, an illustrative example is solved and stress contours are drawn for stress components. In order to verify the results obtained by the proposed solution, comparisons are made with finite difference method (FDM) results. Very good agreements are observed for the teoretical results in comparison with FDM.

Key Words
tensioned anchors; elastic rock; stress distribution; theoretical solution; bond length; bearing plate

Address
Faculty of Mining and Metallurgical Engineering, Amirkabir University of Technology, 424 Hafez Avenue, P.O. Box 15875-4413, Tehran, Iran.

Abstract
Rankine's theory of earth pressure cannot be directly employed to c-φ soils backfill with a sloping ground subjected to complex loadings. In this paper, an analytical solution for active earth pressures on retaining structures of cohesive backfill with an inclined surface subjected to surcharge, pore water pressure and seismic loadings, are derived on the basis of the lower-bound theorem of limit analysis combined with Rankine's earth pressure theory and the Mohr-Coulomb yield criterion. The generalized active earth pressure coefficients (dimensionless total active thrusts) are presented for use in comprehensive design charts which eliminate the need for tedious and cumbersome graphical diagram process. Charts are developed for rigid earth retaining structures under complex environmental loadings such as the surcharge, pore water pressure and seismic inertia force. An example is presented to illustrate the practical application for the proposed coefficient charts.

Key Words
retaining walls; active earth pressure; Rankine's theory; coefficient charts; combined loadings

Address
(1) De-Feng Zheng:
School of Urban and Environmental Science, Liaoning Normal University, Dalian 116029, China;
(2) Ting-Kai Nian, Bo Liu:
School of Civil Engineering & State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China;
(3) Ting-Kai Nian, Ping Yin:
Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology, Ministry of Land and Resources, Qingdao 266071, China;
(4) Lei Song:
State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221008, China.


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