Geotechnical characteristics of effluent contaminated cohesive soils

In developing countries like Pakistan, raw industrial effluents are usually disposed-off directly into open lands or in water bodies resulting in soil contamination. Leachate formation due to rainfalls in openly dumped solid waste also adds to soil contamination. In this study, engineering behavior of soils contaminated by two industrial effluents, one from paper industry (acidic) and another from textile industry (basic), has been investigated. Laboratory testing revealed significant effects of effluent contamination on engineering behavior of tested soils. Liquid limit, plasticity index, optimum moisture content and compression index of tested soils were found to increase with effluent contaminant, indicating a deterioration in the engineering behavior of soils. Whereas maximum dry density, undrained shear strength and coefficient of consolidation of the contaminated soils showed a decreasing trend. The dilapidation in engineering characteristics of soils due to the addition of industrial effluents could pose serious threats to existing and future foundations in terms of loss of bearing capacity and increase in settlement. Keywords: soil contamination, industrial waste, engineering behavior, effluent waste, leachate. First published online: 28 Nov 201

Evaluation of Quality during Construction Projects: A Case Study of Pakistan

Achieving and maintaining quality values are indispensable for attaining organizational and customer satisfaction. This research investigates different aspects of operationalize quality culture and factors affecting the quality of building construction in under developed countries like Pakistan. A qualitative and quantitative survey was circulated among different stakeholders including Clients, Consultants and Contractors to assess the level of the contractor’s performance, the project monitoring and controlling techniques, proper health and safety requirements, client satisfaction and workers experience in construction industry projects. The practice of professional quality management in building projects is increasing, however, many flaws and negligence are still found in local practices. This analysis also indicates that political and socio-economic factors play a significant role in maintaining the quality level in local industry. Therefore, the allocation of sufficient resources, proper training of workers, and recruitment of quality control staff and the use of advanced technologies are recommended for proper implementation of QMS (Quality Management System)

Prediction of Post-Yield Strain from Loading and Unloading Phases of Pressuremeter, Triaxial, and Consolidation Test Curves for Sustainable Embankment Design

Exponential development of post-yield strain (Ԑpost) is a pivotal indicator of failure in embankments constructed on soft saturated clays. This paper characterizes saturated clay stratum comprising very soft to very stiff stratigraphy, with plasticity index (PI) ranging from 19% to 31%, by performing widely used geotechnical engineering tests, i.e., the prebored pressuremeter (PMT) test, the triaxial (TXL) test, and constant-rate-of-strain (CRS) consolidation. PMT, TXL, and CRS tests were performed at a strain rate range of 0.18%/min to 0.21%/min to explore the yield stress (σ′y), the pre-yield strain (Ԑpre), and the post-yield strain (Ԑpost). Results indicate that Ԑpost/Ԑpre for PMT, TXL, and CRS stress–strain curves range from 2.7 to 19 in the loading phase and 2 to 21 in the unloading phase. An exponential increase in Ԑpost/Ԑpre is observed in the range of 10 to 21 for very soft to soft clay which is congruent with the realistic sustainable range of 4 to 30 for embankment failure on soft clays worldwide. The evaluated Ԑpost/Ԑpre can be applied for sustainable prediction of post-failure evolution of strains in embankments on soft clays. Simplistic correlations are developed for approximation and prediction of Ԑpost as a function of σ′y, Ԑpre and maximum applied pressure (Pmax) for loading and unloading phases with reasonable accuracy. The intuitive zone of critical ℇpost is quantified for impending failure in embankments for maximum applied pressure (Pmax), ranging from 36 kPa to 100 kPa for very soft to soft clay for use in sustainable embankment design and construction. Variation in predicted versus measured results of an individual site is observed to be within ±10% of line of equality

EXPERIMENTAL ANALYSIS OF DEPOSITION OF SANDS BY DRY PLUVIATION TECHNIQUE

Obtaining dry density of remolded sand specimens precisely in laboratory has always been an area of interest among researchers in geotechnical engineering. This paper presents the development of a dry pluviation apparatus and its use to prepare dry sand samples in the laboratory to a specified initial relative density. The density and void ratio characteristics of three major sources of sands in Pakistan were investigated through dry pluviation as a function of free fall height. ASTM vibrating table tests on sand samples were also performed to compare index densities with those obtained by dry pluviation apparatus. The results indicate that relative densities up to 100% are achievable in the laboratory using the developed apparatus. A series of regression models have been developed between various parameters associated with dry pluviation

Performance Evaluation of BRT Standard in Decision Support System for Integrated Transportation Policy

Increased urbanization implicated in the form of increased vehicles on roads which burdened limited resources and caused environmental deterioration. To reduce these effects, a Bus Rapid Transit (BRT) system was considered the right solution, requiring minimal infrastructure, as compared to other mass transit options, yet demanding great expertise. This research analyses BRT systems in four cities of Pakistan and the performance evaluation of BRT standards is conducted by developing a statistical model to evaluate predictive BRT standard, which results in identifying the parameters used to improve the performance of the BRT, thus resulting in improved BRT Institute for Transportation and Development Policy (ITDP) standard. As per ITDP, Peshawar BRT was ranked as Gold, whereas Lahore BRT, Rawalpindi/Islamabad BRT and Multan BRT were ranked as Silver. Research describes that ITDP rating can be significantly enhanced if worked in the right direction, taking into account the standards; Peshawar BRT is an example to follow for existing and future BRT in Pakistan. If fully integrated networks of routes and corridors for Lahore, Rawalpindi/Islamabad and Multan BRT have been developed, the model predicts the enhancement of ratings. This paper will assist transport policy makers to strategize in accordance with ITDP standard developed to evaluate and improve the quality of BRT

Use of Plastic Wastes and Reclaimed Asphalt for Sustainable Development

The increased cost of virgin material, declining resources and increasing plastic wastes have turned the research momentum towards sustainable and green pavements. Reclaimed Asphalt Pavement (RAP) from the construction industry and plastic wastes disposal is the main problem for Pakistan as well as other developing countries in the face of fewer funds for the construction, repair, and rehabilitation of the extensive road network. In this research, the attempt has been made to study the use of Reclaimed Asphalt Pavement and plastic wastes to counter these issues. Virgin binder was modified with three different contents (2%, 4%, and 6%) of Polyethylene Terephthalate and three contents (20%, 30%, and 40%) of Reclaimed Asphalt Pavement. Conventional properties of the modified binder were determined by penetration and softening point. At the same time, thermal stability was checked by Thermal Gravimetric Analysis, and resistance against rutting was evaluated with the help of Dynamic Shear Rheometer. It is observed that modified binder remains stable up to a temperature of 470 °C and showed improved resistance against rutting. Marshall mix properties were determined and compared to specifications of the National Highway Authority of Pakistan. Optimum Marshall stability was observed with 4% Polyethylene Terephthalate, and 30% Reclaimed Asphalt Pavement, while flow and air voids remained in limits. As per the results, utilisation of plastic wastes in asphalt pavements enhances the performance and helps to reduce the environmental pollution and landfill problems due to Reclaimed Asphalt Pavement and plastic wastes

Sustainable Application of Wool-Banana Bio-Composite Waste Material in Geotechnical Engineering for Enhancement of Elastoplastic Strain and Resilience of Subgrade Expansive Clays

Agro-biogenic stabilization of expansive subgrade soils is trending to achieve cost-effective and sustainable geotechnical design to resist distress and settlement during the application of heavy traffic loads. This research presents optimized remediation of expansive clay by addition of proportionate quantities of waste renewable wool-banana (WB) fiber composites for the enhancement of elastoplastic strain (ԐEP), peak strength (Sp), resilient modulus (MR) and California bearing ratio (CBR) of expansive clays. Remolded samples of stabilized and nontreated clay prepared at maximum dry density (γdmax) and optimum moisture content (OMC) were subjected to a series of swell potential, unconfined compressive strength (UCS), resilient modulus (MR) and CBR tests to evaluate swell potential, ԐEP, MR, and CBR parameters. The outcome of this study clearly demonstrates that the optimal WB fiber dosage (i.e., 0.6% wool and 1.2% banana fibers of dry weight of clay) lowers the free swell up to 58% and presents an enhancement of 3.5, 2.7, 3.0 and 4.5-times of ԐEPT, Sp, MR and CBR, respectively. Enhancement in ԐEP is vital for the mitigation of excessive cracking in expansive clays for sustainable subgrades. The ratio of strain relating to the peak strength (ԐPS) to the strain relating to the residual strength (ԐRS), i.e., ԐPS/ԐRS = 2.99 which is highest among all fiber-clay blend depicting the highly ductile clay-fiber mixture. Cost-strength analysis reveals the optimized enhancement of ԐEPT, Sp, MR and CBR in comparison with cost using clay plus 0.6% wool plus 1.2% banana fibers blend which depicts the potential application of this research to economize the stabilization of subgrade clay to achieve green and biogeotechnical engineering goals

Investigating users\u27 travel behaviours and perceptions of single-corridor BRT: Lessons from Lahore

Despite the global popularity of bus rapid transit (BRT) in last couple of decades, there is limited empirical evidence in the rapidly urbanizing developing countries regarding corridor-wide users\u27 typical travel characteristics and perceptions of the system attributes. The factors affecting BRT users\u27 (dis)satisfaction are also often disregarded, given less priority than needed, or delayed till issues become more difficult and costlier to manage. Although on a rise, currently only ~10% of BRT systems worldwide are in lower-middle-income and low-income countries, which also supports the need to effectively address BRT passengers\u27 mobility issues in such countries with cramped resources, contributing towards more sustainable urban mass transit systems. As major share of BRTs worldwide are single-corridors (~63%), this study investigates the above stated gaps using case of such BRT in the megacity of Lahore, Pakistan via on-site structured interview surveys using intercept method from BRT users along all stations of the corridor. Typical travel characteristics, correlations and cross-comparisons of sample demographics with mobility attributes, underlying (dis)similar themed factors ensuring internal consistency, and rankings of (dis)satisfactions regarding service attributes were evaluated using combination of statistical methods. Visual comparisons of factors in 2D and 3D rotated space were also explored. Results revealed differences in travel characteristics of BRT users for various demographics; convergence of eight factors from twenty-two service quality attributes; spectrum of highest, average and lowest ranked attributes; and inter-spatial relationship of service quality attributes based on the factors contributing relatively more variation. The overarching findings provide useful insights for transportation practitioners, policy makers and could also contribute towards updating BRT guidelines by incorporating the needs and requirements of BRT users in the developing countries

The Evaluation of Rock Mass Characteristics against Seepage for Sustainable Infrastructure Development

The determination of rock seepage characteristics is a complex phenomenon due to the variability, discontinuities, and formation age of rocks. The available literature on rock mechanics covers empirical relationships and approaches for the estimation of seepage characteristics from the rock mass parameters. In this study, an area comprising of infrastructure such as a water reservoir, embankments, roads, etc., constructed on mix rock mass formations was selected. The field and laboratory tests’ geo-mechanical data for the study area were evaluated. The data obtained from the field geo-mechanical engineering tests like Rock Quality Designation (RQD), Rock Core Recovery, Lugeon, etc., were analyzed. The data retrieved from the geological and geotechnical laboratory tests such as petrography, uniaxial compression, Hoek shear, elastic modulus, etc., were also evaluated. Rock mass was characterized based on petrographic and RQD, and was found in the hybrid formation of igneous, metamorphic, and sedimentary deposits. Seepage analysis in the study area was also carried out based on adit and piezometric data (installed in accordance with the mining technology guidelines), using Seep W Finite Element Method (FEM). The seepage observed in adits were compared with seepage calculated from Seep W. The trend of simulated flux was also presented against K ratio. Seepage quantities for different ranges of K ratio were plotted to evaluate interdependency between seepage and K ratio. Correlations of RQD were developed with hydraulic conductivity “k” for igneous, metamorphic, and sedimentary rocks for quick assessment of seepage characteristics of rock mass by RQD. These correlations and seepage related evaluations will be beneficial for the characterization of rock mass in relation to seepage for sustainable infrastructure development

The Evaluation of Rock Mass Characteristics against Seepage for Sustainable Infrastructure Development

The determination of rock seepage characteristics is a complex phenomenon due to the variability, discontinuities, and formation age of rocks. The available literature on rock mechanics covers empirical relationships and approaches for the estimation of seepage characteristics from the rock mass parameters. In this study, an area comprising of infrastructure such as a water reservoir, embankments, roads, etc., constructed on mix rock mass formations was selected. The field and laboratory tests’ geo-mechanical data for the study area were evaluated. The data obtained from the field geo-mechanical engineering tests like Rock Quality Designation (RQD), Rock Core Recovery, Lugeon, etc., were analyzed. The data retrieved from the geological and geotechnical laboratory tests such as petrography, uniaxial compression, Hoek shear, elastic modulus, etc., were also evaluated. Rock mass was characterized based on petrographic and RQD, and was found in the hybrid formation of igneous, metamorphic, and sedimentary deposits. Seepage analysis in the study area was also carried out based on adit and piezometric data (installed in accordance with the mining technology guidelines), using Seep W Finite Element Method (FEM). The seepage observed in adits were compared with seepage calculated from Seep W. The trend of simulated flux was also presented against K ratio. Seepage quantities for different ranges of K ratio were plotted to evaluate interdependency between seepage and K ratio. Correlations of RQD were developed with hydraulic conductivity “k” for igneous, metamorphic, and sedimentary rocks for quick assessment of seepage characteristics of rock mass by RQD. These correlations and seepage related evaluations will be beneficial for the characterization of rock mass in relation to seepage for sustainable infrastructure development