Experimental and Numerical Modeling of VersaTrap Type G

This paper presents the processes and results of experiments carried out on the solids separation performance of a vortex combination. The vortex is generated in a cylindrical chamber above the level of a cylindrical screen. Rocla VersaTrap type G (VTG) which is designed to treat stormwater pollutants from commercial and residential developments was used in this research. Experimental and numerical analysis were conducted on the scale model to establish the hydraulic characteristics and pollutant removal efficiencies (PRE). To replicate typical in situ conditions, the VTG with 0%, 25%, 50%, 75% and 100% blocked screen conditions, were experimentally tested at Curtin University of Technology. Comparing Computational Fluid Dynamic simulation and experimental results suggest that CFD software is an effective tool for assessing the outcomes of the hydraulic treatment system. Data analysis has proved that the head loss increases in proportion to screen blockage condition. The separation efficiencies are inversely proportional to flow rates. The study findings have capabilities to optimize any other types of stormwater treatment systems

A Review on the Performance of Modified Cam Clay Model in Predicting the Mechanical Behaviour of Heavily Overconsolidated Clay

The Modified Cam Clay (MCC) is one of the most commonly used soil models, which is very popular in the world. It was developed by the researchers at the University of Cambridge, U.K. This MCC model has gained general acceptance amongst the researchers in the field of geotechnical engineering. Some commercial softwares for geotechnical problems are using the MCC model as the basis of analysis. The MCC model undoubtedly works very well for predicting the mechanical behavior of normally consolidated clay, but in reality some soils are in the state of overconsolidated. This study is aimed to find out some pitfalls in using the MCC model in relation to its application on overconsolidated soils. Some data from plane strain testing on the overconsolidated clay were used to examine the application of MCC model on overconsolidated clay. The results showed that, the MCC model is no longer able to simulate the mechanical behavior of heavily overconsolidated clay; the MCC calculation for heavily overconsolidated clay was deviated far below the experimental result

Sustainable use of construction and demolition (C&D) waste as A road base material

Crushed concrete waste is a by-product from building demolition and constitutes a principal component of municipal solid waste consisting of concrete, sand, brick, rock, metals and timber. Over 50% of this waste is commonly sent to land-filled sites, resulting in the impact on the limited capacity of land-filled sites. Nowadays, the sources of virgin natural aggregates are depleted by increasing in demand of using a virgin material in building and infrastructure construction and maintenance facilities. This depletion leads to the utilisation of crushed concrete waste to replace natural aggregates in road and highway construction. Of key significance of this study is to present alternative materials for road and highway construction on the production of the proper guideline for road base by using crushed concrete waste. Sophisticated tests were conducted to investigate the mechanical responses of compacted crushed concrete subjected to applied loads simulated from traffic loads. Unconfined compressive strength, shear strength parameters, resilient modulus and permanent deformation of such material were determined. Our findings showed that crushed concrete waste is able to utilise as a road base material. The results of this study will enhance increased use of crushed concrete waste in road and highway construction and will, therefore, alternatively reduce consumption and costs in manufacturing virgin aggregates

Interfacial shear strength of rubber-reinforced clays: a dimensional analysis perspective

The present study aims towards the development of practical dimensional models capable of simulating the interfacial shear strength of rubber-reinforced clays. Two types of recycled tire rubbers (of fine and coarse categories) were each incorporated into the soil at four different contents (by weight), and statically compacted at their respective Proctor optimum condition for direct shear testing. The rubber inclusions amended the soil through improvements achieved in two aspects: (i) frictional resistance generated as a result of soil–rubber contact; and (ii) mechanical interlocking of rubber particles and soil grains. In general, both amending mechanisms were in favor of a higher rubber content, and to a lesser degree a larger rubber size. The dimensional analysis concept was extended to the soil–rubber shear strength problem, thereby leading to the development of practical dimensional models capable of simulating the shear stress–horizontal displacement response as a function of the composite's basic index properties. The predictive capacity of the proposed models was examined and validated by statistical techniques. The proposed dimensional models contain a limited number of fitting parameters, which can be calibrated by minimal experimental effort and hence implemented for predictive purposes.A. Soltani, A. Deng, A. Taheri, M. Mirzababaei, H. Nikra

Enhancing civil engineering surveying learning through workshops

Abstract: Surveying in an undergraduate civil engineering curriculum needs a substantial amount of hands-on training to obtain adequate learning outcomes. A lecture-only mode of delivery does not provide the adequate surveying skills needed by an engineering student. In 2009, workshops were introduced for the CVEN2000 Civil Engineering Drawing and Surveying unit at Curtin University, Australia, with the aim of offering students hands-on training in surveying to enhance their learning. This study analyzes data collected from 160 students in 2012 and 2013 using confidence limits, correlations, frequency percentage distribution, and principal component analysis to evaluate if the introduced workshops contributed to the enhancement of (1) the students acquiring industry-based skills and (2) the students’ overall learning of engineering surveying, which is a practical-oriented course. Additionally, qualitative analysis fromCurtin’s official eVALUate and examination results were used to verify the findings of the previously mentioned contributions. The results indicate that workshops contributed to the development of the students’ overall learning skills, with the top agreement of the students being critical thinking skills (93.6%), handling problems (96.6%), and correlating theory (97.9%). Qualitative analysis of the 2013 data indicates that 70% of the students agreed that their overall learning skills were enhanced and that the workshop sessions prior to the assessed fieldwork of setting out the horizontal curves enhanced their communication and teamwork skills. Overall, 97.9% of the students were satisfied with the workshops, and 98.9% of the students said that they would recommend them as an effective learning tool to their friends. The main lesson learned from the data presented in this paper is that students were satisfied with the workshops and recognized/perceived them to contribute to the development of the learning attributes they need to acquire

Landslide Risk Assessment by Using a New Combination Model Based on a Fuzzy Inference System Method

Landslides are one of the most dangerous phenomena that pose widespread damage to property and human lives. Over the recent decades, a large number of models have been developed for landslide risk assessment to prevent the natural hazards. These models provide a systematic approach to assess the risk value of a typical landslide. However, often models only utilize the numerical data to formulate a problem of landslide risk assessment and neglect the valuable information provided by experts’ opinion. This leads to an inherent uncertainty in the process of modelling. On the other hand, fuzzy inference systems are among the most powerful techniques in handling the inherent uncertainty. This paper develops a powerful model based on fuzzy inference system that uses both numerical data and subjective information to formulate the landslide risk more reliable and accurate. The results show that the proposed model is capable of assessing the landslide risk index. Likewise, the performance of the proposed model is better in comparison with that of the conventional techniques

Geotechnical approach to use paper in soil

Reinforced soil has been among the most effective soil modification materials. Its use has been expanded rapidly into civil engineering, geotechnical engineering and pavement engineering. Reinforcing subgarde in pavement systems has always been an issue. This study focuses on effect of paper inclusion on the modulus of elasticity of subgrade material. Paper was used for this investigation. Paper contents and aspect ratio have been changed during these tests. The paper percentage varied from 0 % (for unreinforced samples) to 30%. Clay was used as sub grade material. Unconfined compression tests were carried out to investigate behaviour of the composite under different condition. The paper reinforcment length and paper reinforcment content found to play important rule on the modulus of elasticity of paper reinforced samples. Furthermore it was observed that ductility of sample increased by paper inclusion

Evaluation of the hirsch model for dynamic modulus estimation of asphalt mixtures

Copyright © 2017 ISEC Press. The dynamic modulus of the asphalt mixtures is an important factor in designing or analyzing an asphalt concrete pavement, but it is expensive and time consuming to measure. Therefore, it is important to develop a model to predict this value. In this regard, the Hirsch model is a popular model, however, it is developed based on a range of U.S. asphalt mixtures and standards. Therefore, it is not certain that it can be used for asphalt mixtures based on materials and codes other than U.S. This article investigated whether this model performs satisfactorily with two typical asphalt mixtures in Western Australia (WA) containing 0, 10, 20, and 30% of recycled asphalt pavement. To do so, cylindrical samples were made with materials and locally established standards in Western Australia and then tested in Asphalt Mixture Performance Tester (AMPT) machine to acquire their dynamic modulus and phase angle values in different loading frequencies (0.01 to 10 Hz) and temperatures (4 to 40°C). Meanwhile, the results are estimated by the Hirsch model using some properties of the mixture and binder. The properties of the binder in different test conditions are obtained using a dynamic shear rheometer. The comparison of the results showed that the dynamic modulus underestimation or overestimation error can reach to 50 and 280% respectively. Generally, this model did not perform well in this study

Paper reinforcement and soil

Composite soils have been extensively used in civil engineering applications, especially in slopes, embankment dam and landfills. This paper aims to investigate effect of paper reinforcement inclusion on compaction characteristic of composite soil (i.e. clay composite). A series of laboratory tests performed to assess reinforcement effect on optimum water content and maximum dry unit weight of composite soils. Clay was selected as soil part of the composite and paper was used as reinforcement. The paper reinforcement parameters differed from one test to another, as paper length varied from 15 mm to 40mm and paper content were selected as 5% and 10%. For each test, compaction curved derived and the results were compared. The results proved that inclusion of paper affected compaction behaviour of samples so that increasing in paper content and length caused increasing in Optimum Moisture Content (OMC) and slightly decreased maximum dry unit weight

Experimental approach to suffusion and backward erosion

Internal erosion in dams is viewed by engineers as being of particular concern with regard to safety, as there is a danger that there may be no external evidence, or only subtle evidence, that the erosion is taking place. A dam may breach within just a few hours of internal erosion becoming apparent. In order to assist in finding a solution to the lack of external evidence, a series of experimental tests was developed. The tests consisted of applying hydraulic stresses to reconstructed consolidated cohesive soils to evaluate different types of internal erosion (i.e. suffusion and backward erosion). Different parameters such as hydraulic gradient, confining pressure and clay content were examined. When the hydraulic gradient was small, it was concluded that the erosion of the structure's clay fraction was due to suffusion. When the hydraulic gradient increased, it was concluded that the sand fraction erosion commencement was due to backward erosion. Moreover, the clay content was found to be an important parameter leading directly to internal erosion. The effects of confinement on internal erosion, unlike suffusion, increased backward erosion