土木与环境工程学报

Emergent incident of fish kill was occurred in the detention pond of natural water purification system. The objective of this study was revealed the cause of the incident.Novel measurements unprecedentedly employed in this study including SOD to measure sediment oxygen decay PCR to find out sediment microbial activity, SEM, EDX, and FTIR to view the macrophyte rhiyphere root surface to understand the pollutant adsorption. Algal bloom was the main reason to induce serious fish kill Particle size analysis demonstrated greater particles were setting in the upstream.Chlorophyll A, COD, SS, phosphorus, E coli was in descending of following the stream direction. The end of measuring point, detention pond, demonstrated the serious eutrophication which leads to diurnal pH and DO fluctuation to induce anoxic condition at night which induced fish kill. Sediment oxygen uptake (SOD) also measure to fine vertical oxygen profile. SEM, EDX, and FTIR results indicated the major functional groups of submergent macrophyte reed root were carboxyl, carbonyl, and phenol which could adsorp various pollutants.

More than 15 million tons of aggregates are imported each year to Qatar from neighbouring countries. Large quantities of waste materials (around 20 million tons/year) from excavation waste, demolition rubble and reclaimed asphalt pavement (RAP) are being generated. The main objective of this paper is to present the results on the use of combined excavation waste (EW) and RAP aggregates in the construction of road bases and sub-bases. Physical and chemical properties were determined. Different combinations of both materials were subjected to compaction and California Bearing Ratio (CBR) testing in accordance with Qatar Construction Specifications. Results indicated that, for the materials tested, it is not feasible to use excavation waste, RAP aggregates or a combination of the two materials in road bases and sub-bases. The materials failed to meet some Qatari standards such as Los Angeles abrasion, liquid limit, plasticity index and CBR specified for road construction.

Study of effect of single fiber pull out test result on flexural performance of Engineered Cementitious Composite (ECC) is carried out in the present work. Cement: sand ratios of 1:0.5, 1:1, 1:1.5, and 1:2 are used in composition of ECC. Beams of 20 and 30 mm depth are tested under displacement control and four point loading arrangement. First crack strength, ultimate strength, toughness index, deflection hardening and reserved flexural strength are evaluated. Single fiber pull out test of 6 mm embedded length is carried out to evaluate frictional bond strength. An equation is suggested to evaluate ultimate flexural strength of ECC considering effect of micromechanical parameters in general and frictional bond strength in particular.

In many literatures, studies show that infill’s modify the behavior of framed structures under lateral loads; the contribution of panels is generally neglected in common structural analyses. The structural effect of brick infill is generally not considered in the design of columns as well as other structural components of RC frame structures. The brick walls have significant in-plane stiffness contributing to the stiffness of the frame against lateral load. The lateral deflection is reduced significantly in the infilled frame compared to the deflection of the frame without infill. It is observed that frames with infill produce much smaller deflections as compared to frames without infill. The results reflect the significance of infill in increasing the strength, stiffness and frequency, of the entire system depending on the position and amount of infilling. Lower infilling is noted to provide more stiffness for the system as compared with upper locations. A number of non-linear static (pushover) analyses were performed on proper structural models of the building, considering both bare framed structure and the infilled one, in order to appraise the influence of infill walls on the failure mechanisms. In particular, a sensitivity analysis was performed by assigning different Partial Safety Factors (PSF) to the mechanical parameters of infill walls, in order to investigate their effect on the overall structural response of the building.

The transport of contaminants has been a problematic issue for many years, mainly due to the adverse impact of the contaminants on the quality of groundwater. In order to analyse this, this study has developed a prediction model that allows the early detection of possible contamination. Firstly, the paper introduces the concept of the modelling of contamination transport through a soil matrix. Then it presents a two-dimensional Convection-Dispersion Equation (CDE) for contaminant transport in a soil matrix. This includes the investigation of different reaction coefficients and time-dependent inlet boundary conditions, from which a numerical solution is derived. The study also verifies recent previous work in this area through the use of numerical programming. The results for soil contamination in two dimensions are presented in this research.