Nepal Journal of Civil Engineering

Preparing Your Paper in LATEX for Nepalese Journal of Civil Engineering

Jayandra Raj Shrestha — 2021-01-31

This is a working template for the research article for Nepalese Journal of Civil Engineering. The template has been typeset in LATEX. You have to replace certain sections of this template by your content and produce a pdf file as final output. Format for different types of elements that could occur in the paper are already defined in this template. The authors are to strictly follow the style/formatting as defined in this template for consistencies in a single paper and across different papers. The contents of the paper appears in a two column format, with an exception of the paper title, author names, affiliations, abstract and keywords. Your paper should be limited to 8 pages and abstract should not exceed 300 words. Each of the keywords need to be separated by commas as given in the example below.

Evaluation of the Land Surface Temperature using Satellite Images in Kathmandu Valley

Anil Aryal — 2021-01-31

Urbanization leads the conversion of green area to built-up area which eventually leads to increase in surface temperature and creates the urban heat islands. Kathmandu Valley (KV), one of the growing mega cities in South Asia in-terms of population density and urbanization, requires the monitoring of urban morphology for the proper assessment. Use of satellite images makes the work more easier. The present study focuses on the evaluation of Land Surface Temperature (LST) as a preliminary work of monitoring urban and periurban areas of Kathmandu Valley. We used Landsat-8 satellite images as an input to evaluate LST over different administrative units for the study period 2013-2019. The results of research showed that Kathmandu, Bhaktapur and Lalitpur administrative units have higher average LST (ranging from 22.1 to 36.9°C in the month of March and June respectively) comparing to other administrative units. The average LST was found to be higher in the month of June. The temporal results of LST portrays 2015 as the hottest year during the study period. Also, spatial and temporal evaluation of LST in KV suggests to increase the more green space in the urban areas to minimize surface temperature. Finally, the authors of current research recommends using the concept of remote sensing (satellite image analysis) as an alternative tool for monitoring urban morphology.

Pollutant Removal Abilities of Horizontal Subsurface Flow Constructed Wetland

Amit Kumar Maharjan — 2021-01-31

With the rapid urbanization, the production of wastewater is increasing day by day. Direct discharge of wastewater in the water bodies/land causes environmental pollutions. Hence, treatment of the wastewater is must, prior to the disposal. Treatment of wastewater through constructed wetlands (CWs) require low cost, less energy consumption, easy construction, and simple operation/maintenance. So, CWs can be the better option for the developing countries such as Nepal. Main objective of the study was to determine the pollutant/nutrient removal abilities of total nitrogen (N), total phosphorous (P), potassium (K⁺), and biochemical oxygen demand (BOD) in the horizontal subsurface flow (HSSF) CW. The study was carried out in the HSSF CW having gravel as substrate material and common reed (narkat, phragmites karka) as macrophyte. The CW treated domestic wastewater at an average flow rate of 8.64 m³.d⁻¹. The first order removal rate constants were 0.015 m⁻¹ (0.200 d⁻¹) for total N, 0.035 m⁻¹ (0.484 d⁻¹) for total P, 0.004 m⁻¹ (0.052 d⁻¹) for K⁺, and 0.055 m⁻¹ (0.753 d⁻¹) for BOD₅. The influent concentration of total N, total P, K⁺, and BOD₅ ranged from 60-100, 11-13, 34-48, and 60-120 mg.l⁻¹, respectively; effluent concentration from 35-55, 1-3, 31-38, and 4-20 mg.l⁻¹, respectively. Average removal efficiencies of total N, total P, K⁺, and BOD₅ were 50.5, 75.5, 15.0, and 86.9 %, respectively. CW will be a promising option for wastewater treatment.

Determination of Forces on Anchor Blocks and Stability Analysis in a 3 Dimensional Plane with Vector Approach

Gaurav Atreya — 2021-01-31

The Anchor blocks are the structures that take most of the forces acting on the pipe bends and transfer it safely to the ground. Since the stability of the Anchor Blocks is a function of its weight, the economic design comes with accurate calculation of the forces. Although several sources have the design calculations for Anchor Blocks, there is room for improvements for 3D calculations. The calculation of the forces is hard to visualize in a two-dimensional plane as numerous planes have to be made for the analysis. The purpose of this paper is to use the 3D vector mechanics so that forces can all be represented by global vectors in X, Y & Z direction and henceforth are easy to study. By doing so the intermittent calculations, as well as the end results, are efficient, coherent and scalable (to any number of a joint like T-joint, or combination of bends and joints). The formulae and procedures are developed with consideration of developing a well-organized CAD-based software for an even better analysis of a variety of irregular shapes in the future with reduced human efforts.

Numerical Simulation of Meandering Effects on Velocity Field and Separation Zone past a Spur Dike in Rigid Bed

Mukesh Raj Kafle — 2021-01-31

This study presents a numerical model to simulate two-dimensional flow field near a vertical impermeable spur dike in a sine-generated rigid bed meandering channel. Comprehensive study of resultant velocity and separation zone past the spur dike on five different channels with meandering angles 0°, 15°, 30°, 45° and 60° were carried out and compared. The CFD model Nays 2D was used to simulate the flow field. Cubic- Interpolated Pseudo-Particle (CIP) method was used as finite difference method to analyze the advection terms. The study reveals that unlike straight channel, flow field and separation zone past the spur dike are influenced by the position of spur dike and angle of meandering. For meandering angle equal or greater than 60° and position of spur dike at s^*=0.5 with reference to the straight rectangular channel from the upstream end on the right bank, significance of spur dike as a flow deflector does not prevail. With the same flow parameters and channel characteristics, the velocity amplification is maximum to angle of meandering equal to 30°.

Estimation of Construction Duration for Roads and Bridges in Nepal

Prakriti Pokhrel — 2021-01-31

Precise estimation of contract duration is a tough job in the construction field given the uncertainties involved in it. The construction industry for Roads and Bridges in Nepal is in a transitional phase and the working procedures varies on the individual capacity of each contractor. So, a practical approach is necessary for developing a methodology for estimation of duration. At present the estimated contract duration lacks uniformity among the projects of similar size and nature. With time extension issue getting much attention in recent amendments of PPR, estimation of duration has yet in the shadows among the lawmakers. This research aims at developing an empirical formulae for determination of contract duration based on the historical data of roads and bridges completed within the last five years. A total of 83 bridges and 78 road projects were analyzed. Regression analysis was carried out for developing a mathematical relation between time and cost of the project. The data was made to fit in Browmillow’s time-cost model. Apart from the cost of the project, there are other factors that affect the duration of the project. To address these project specific requirements, modification were recommended to the time-cost model by introducing coefficients in the empirical relation. As per the obtained equation, contract duration is directly proportional to the cost. However, the rate of increase in contract duration decreases with increase in cost. The reason for this is due to the higher level of parallel activities and better use of technologies for the contracts with higher cost. This model can be useful for government agencies, contractors and consultants involved in construction and procurement of roads and bridges in Nepal. The empirical formula obtained as an outcome of this research is applicable for roads and bridge projects of Nepal with estimated amount greater than two crore.

Factors Influencing Sand Re-liquefaction in Shaking Table Test

Dikshit Babu Nepal — 2021-01-31

Cases of historical earthquakes show that liquefied sand deposits may undergo re-liquefaction yet again by a succeeding earthquake. However various factors such as the depth of sand deposits, peak ground acceleration, and shaking duration of an earthquake can affect the re-liquefaction occurrence. To understand this underlying mechanism, a series of shaking table experiments were performed by varying the depth of sand model, peak ground acceleration, and shaking duration of input motion. The excess pore water pressure and the acceleration response of the sandy model in the process of re-liquefaction in the sand were measured. The test result demonstrated that during a subsequent re-liquefaction, shear wave propagation mechanism and the number of times sand re-liquefy varies with the depth of sand model suggesting that the re-liquefaction resistance is depth-dependent, and the soil layer near the surface is most likely to be liquefied. The analysis by varying peak ground acceleration and shaking duration of input motion indicated that the model subjected to shorter duration and higher peak ground acceleration of input motion have a greater tendency to re-liquefy in multiple number of shaking, signifying that the conventional strategy for liquefaction resistance needs to be improved before it can be implemented for the analysis of site liquefaction. Based on the findings of parametric studies, there exists a critical liquefaction void ratio within a zone with which we can forecast the presence or absence of liquefaction in the future earthquakes.