International Journal of Civil Engineering
Volume:12 Issue: 2, Apr 2014

Driven Precast Reinforced Concrete Piles (DPRCP) is extensively used as a foundation for bridges constructed over canals in Egypt in order to avoid the diversion of water canals. The objectives of this research include identifying the main activities of DPRCP execution in the bridge-construction industry in Egypt and the risk factors affecting them. In addition, assessment of the effects of these risk factors on the quality of activities of DPRCP. Four activities are identified in order to execute the process of construction of DPRCP. These activities include: preparing and casting piles, positioning piles and steering the driving machine, handling piles, and driving piles. Thirty one risk factors affecting the DPRCP activities execution are identified. A survey was executed in Egypt concerning probabilities of occurrence of these factors and their impacts on the quality of activities of DPRCP. In addition, a new membership function is introduced to represent the quality of activities and used in a fuzzy model for factors assessment. Results showed that the proposed membership function can be used effectively to assess the quality of activities associated with the construction of DPRCP. A list of risk factors is highlighted to show the most critical risk factors that help in preparing the quality management plan for the upcoming similar projects. The gentile distribution of data obtained for the different activities proved that the investigated risk factors for the DPRCP in this study are significant.

This paper presents a simple solution based on the limit equilibrium of sliding soil wedge of reinforced backfill subjected to the horizontal acceleration in the framework of the pseudo-static method. In particular, contrary to most studies on the reinforced retaining wall, the solution proposed in this study, takes into account the effect of the uniform surcharge on the reinforced backfill soil and of its distance from the face of the wall. The results are investigated in dimensionless form of the maximum reinforcement required strength (Kmax), the dimension of the sliding wedge (Lc/H), and the factor of safety (FS). Compared to the reinforced backfill without surcharge, the presence of surcharge over the reinforced backfill and of its distance from the top of the backfill have significant effects on the stability of the system. For a fixed surcharge, a minimum distance of surcharge exists for which the presence of the surcharge does not affect the solution and the failure mechanism is that corresponding to the case of system with no surcharge. A detailed design example is included to illustrate usage of proposed procedures. Comparisons of the present results with available results show a favorable agreement.

This paper presents time domain fundamental solutions for the extended Biot''s dynamic formulations of two-dimensional (2D) unsaturated poroelasticity. Unsaturated porous media is considered as a porous media in which the voids are saturated with two immiscible fluids, i.e. liquid and gas. At first, the corresponding explicit Laplace transform domain fundamental solution is obtained in terms of skeleton displacements, as well as liquid and gas pressures. Subsequently, the closed-form time domain fundamental solutions are derived by analytical inversion of the Laplace transform domain solutions. Finally, a set of numerical results are presented which verifies the accuracy of the analytically inversed transient fundamental solution and demonstrates some salient features of the elastic waves in unsaturated media.

The total coal and lignite consumption of the thermic power plants in Turkey is approximately 55 million tons and nearly 15 million tons of fly ash is produced. The remarkable increase in the production of fly ash and its disposal in an environmentally friendly manner is increasingly becoming a matter of global concern. Studies for the utilization of fly ash in Turkey are necessary to reduce environmental problems and avoid economical loss caused by the disposal of fly ash. Efforts are underway to improve the use of fly ash in several ways, with the geotechnical utilization also forming an important aspect of these efforts. An experimental program was undertaken to investigate the effects of Multifilament (MF19average) and Fibrillated (F19average) polypropylene fiber on the compaction and strength behavior of CH class soil with fly ash in different proportions. The soil samples were prepared at three different percentages of fiber content (i.e. 0.5%, 1% and 1.5% by weight of soil) and two different percentages of fly ash (i.e. 10% and 15% by weight of soil). A series of tests were prepared in optimum moisture content and laboratory unconfined compression strength tests, compaction tests and Atterberg limits test were carried out. The fiber inclusions increased the strength of the fly ash specimens and changed their brittle behavior into ductile behavior.

A simplified approach for nonlinear analysis of the load-displacement response of a single pile and a pile group is presented using the load-transfer approach in this work. A hyperbolic model is used to capture the relationship between unit skin friction and pile-soil relative displacement developed at the pile-soil interface and the load-displacement relationship developed at the pile end. As to the nonlinear analysis of the single pile response, a highly effective iterative computer program is developed using the proposed hyperbolic model. Furthermore, determinations of the parameters presented in the hyperbolic model of skin friction and end resistance of an individual pile in a pile group are obtained considering interactions between piles. Based on the determinations of the parameters presented in the hyperbolic model of an individual pile in a pile group and the proposed iterative computer program developed for the analysis of the single pile response, the conventional load-transfer approach can then be extended to the analysis of the load-settlement response of an arbitrary pile in a pile group. Comparisons of the load-settlement response demonstrate that the proposed method is generally in good agreement with the field-observed behavior and the calculated results derived from other approaches.

In this paper, normalized displacement amplitude of the ground surface was presented in the presence of the semi-sine shaped valley above the truncated circular cavity embedded in a homogenous isotopic linear elastic half-plane, subjected to obliquely propagating incident SH waves as Ricker wavelet type. The proposed direct time-domain half-plane boundary element formulation was used and extended to analyze the combined multi-boundary topographic problems. While using it, only boundary of the valley and the surrounding cavity should be discretized. The effect of four geometric parameters including shape ratio of the valley, ratios of the depth, horizontal location, truncation thickness of the cavity and incident wave angle was investigated on the responses at a single dimensionless frequency. The studies showed that surface behavior was completely different due to complex topographic features, compared with the presence of either valley or cavity alone. In addition, the cavity existence below the surface could play a seismic isolation role in the case of vertical incident waves and vice versa for oblique waves.

It introduced an innovative bioengineering method of consolidating incompact sand by urea-hydrolysis producing calcite cementation under the inducement of urease producing microbe. In the paper it discussed the effects of cementation methods and time on porosity and mechanical properties of microbe-inspired cementing sand columns. Method A adopted reaction fluid gravitational permeating and external pressing and method B adopted reaction fluid gravitational permeating and outlet intermittent plugging method. 28-day sand columns prepared by method A exhibited stronger mechanical properties than those prepared by method B, considering of the compressive strengths and three-point flexural strength as well. Pore volume fractions of sand columns prepared by method A reduced with an increase in cementation time which represented the bulk densities of sand columns were improved positively with time. The compressive strengths and the flexural strengths of sand columns prepared by method A increased with time. All these improved mechanical properties were attributed to the fact that the increasing amount of microbe inspired calcite precipitation with time consolidated sand columns by filling or bridging in sand gaps.

In this technical note, a methodology is introduced for reliability calculation of consolidation settlement based on cone penetration test (CPT) data. The measured data of corrected cone tip resistance (q_t) is detrended using a quadratic trend and the residuals are assumed to be lognormally distributed random field. Realizations of q_t is generated by using statistical parameters of residuals including standard deviation and the scale of fluctuation. The quadratic trend and the generated residuals are then combined to correlate shear and bulk modulus as input consolidation properties for coupled analysis and subsequently consolidation settlement was calculated by using finite difference method adopted in Monte Carlo simulations. The results of reliability analysis are presented describing the range of possible settlements by considering characteristics of uncertainties involved at the particular site. Maximum possible settlements must be smaller than the allowable settlement to guarantee proper performance.