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Three dimensional (3D) failure pattern of flexible pile due to lateral cyclic loading in sand M. F. Awad-Allah; N. Yasufuku; S. Manandhar
Lowland Technology International Vol 19 No 1, June (2017)
Publisher : International Association of Lowland Technology

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In this paper, a set of small-scale laboratory single flexible pile model was conducted in a medium dense Toyoura sand environment under the effect of cyclic lateral loads. Digital images were captured for the plastic deformations of the soil during the lateral loading from the top of the testing chamber. Combination of photo image analysis and analytical cyclic p-y curve methods was implemented for estimating the three dimensional (3D) failure zone adjacent to pile shaft. The 3D failure pattern of the soil around single pile shaft was investigated through two steps, including: (1) determination of the range of lateral plastic deformations at the top of ground surface in perpendicular and parallel directions of cyclic loads; and (2) determination of the point of rotation (zero displacement) along the pile shaft. Experimental results showed that a conical passive zone of plastic deformations is established around pile shaft due to applying two-way lateral cyclic loading at pile head. Based on the findings, design considerations for piles subjected to lateral cyclic loading have been introduced.

Influences of Long-Term Tectonic and Geo-Climatic Effects on Geotechnical Problems of Soft Ground - Ulaanbaatar, Mongolia S. Manandhar; T. Hino; K. Kitagawa
Lowland Technology International Vol 18 No 1, June (2016)
Publisher : International Association of Lowland Technology

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Ulaanbaatar city situates in Ulaanbaatar Folded System with presence of Mongolo-Baikal seismic zone. The presence of the Tuul River Valley dissected the basin with the formation of soft sediments transported by fluvial and Aeolian environments. The presence of scattered permafrost soil due to geo-climatic condition has led to freeze-thaw phenomena by physical weathering of the ground. This study reveals the influences of long-term tectonic and geo-climatic effects have brought up geotechnical problems in the area. Further it is advised that special attention need to be given in settlement of the area associated with mechanical disintegration of the ground, characterizing similar with lowlands along the valley bottom.

Damages and causative factors of 2015 strong Nepal Earthquake and directional movements of infrastructures in the Kathmandu Basin and along the Araniko Highway S. Manandhar; T. Hino; S. Soralump; M. Francis
Lowland Technology International Vol 18 No 2, Sep (2016)
Publisher : International Association of Lowland Technology

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The strong earthquake on April 25, 2015 (7.8 Mw) and the aftershock on May 12, 2015 (7.3 Mw) claimed the lives of 8,659 people, plus 21,150 people injured and huge economic loss together with serious damages on eight World Heritage sites. Our two field surveys in the month of from May 9-21, 2015 and 19-23 July, 2015 revealed understanding of damages to traditional towns, historical monuments, and modern buildings. Regionally, damages on buildings are confined to the traditional houses which are remnants of or renovated after the 8.1 magnitude 1934 AD earthquake. Widespread cases of inadequate engineering and construction practices for RCC (Reinforced Cement Concrete) buildings and renovated old buildings have been severely affected. The affected region includes the main shock along the 150 km long rupture zone towards east. The aftershock reached farther south at a shallower depth towards the end of the eastern rupture zone. As a result damages inflicted in the structures from both quakes revealed different shaking directions. The April 25 main shock caused eastward leaning structures while May 12 aftershock caused southward leaning and/collapsed structures. It is important to identify whether the direction is due to aftershock at the end of initial rupture zone or if it represents a newly exposed fault.

Investigation of the safety factor and reliability of the embankment in soil cement column improved ground on Saga lowland Y. Jabeur; S. Manandhar; S. Shrestha; T. Hino; M. Mbodji; T. Himeno
Lowland Technology International Vol 20 No 4, March (2019): Special Issue on: Green Technology for Sustainable Infrastructure Develop
Publisher : International Association of Lowland Technology

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Saga plain constitutes thick deposited soft marine clay which is susceptible for the construction of any civil engineering structures with reference to large and differential settlement problems in the area. This paper presents the case study of the Ariake sea coastal road project failure on Ashikari region in Saga lowland. In this region, the group of soil cement columns as ground improvement technique is adopted for the construction of the highway embankment. The estimation of probability of failure of the embankment on the stabilized soils is approached through the probabilistic analysis for this research. The assessments of total safety factor (Fs) and reliability rely on random variables of geotechnical parameters. These random variables considered for this study are the unit weights of the soil materials (γ) (fill and clay), the undrained shear strength (cu) in the embankment fill material and undrained shear strength of the stabilized soil and soft soil. Furthermore, the paper also delineates judgment of the geotechnical risk assessment based on real site condition.

Influence of Topographic Effect on Dynamic Behavior of Hill Slope Building N. Gajurel; S. Manandhar; M.R. Bhatt
Lowland Technology International Vol 21 No 4, March (2020): Special Issue on: Engineering Geology and Geotechniques for Developing Co
Publisher : International Association of Lowland Technology

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This research was driven by observations made during the April 2015 Gorkha Earthquake, in which buildings located on the cliffs and hillslopes suffered significant damage. The primary goal of this research is to study the impact of topography on the dynamic behavior of buildings located on the slopes of hills, which are popular residential sites spread across Nepal. The numerical simulation of topographic effect was done using Ground Response Analysis. 2D geological models were made, over which seismic simulation were done. The results are presented in the form of topographical amplification factor (TAF). The amplification factor calculated from ground response analysis were used in static and linear dynamic time history analysis of the buildings. The response of a two-storied structure is compared with and without considering the effect of topography. The outcome demonstrates that, owing to topographic impact, hill-slope structures built using contemporary seismic design codes are not sufficient to withstand the enhanced seismic forces.

Building a More Resilient Nepal-The Utilisation of the Resilience Scorecard for Kathmandu, Nepal following the Gorkha Earthquake of 2015 M.R.Z. Whitworth; A. Moore; M. Francis; S. Hubbard; S. Manandhar
Lowland Technology International Vol 21 No 4, March (2020): Special Issue on: Engineering Geology and Geotechniques for Developing Co
Publisher : International Association of Lowland Technology

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Following the Gorkha earthquake of 2015, the opportunity exists to utilise the Resilience Scorecard to assess the current level of preparedness of Kathmandu. This article will discuss the application of the UN Resilience Scorecard, with the assessment undertaken forming a baseline assessment addressing core infrastructure issues from the earthquake and evaluating core community functions. The assessment looks at initially 3 pillars of the Resilience Scorecard through 3 core components: 1. The disaster cycle: From preparedness through response recovery to developing risk scenarios. 2. The operational capacity of the financial, governmental and societal institutions. 3. The resilience of the society from urban to rural including infrastructure and natural buffers. This paper highlights the key findings of the assessment undertaken during field visits to Kathmandu Valley following the April 2015 earthquake. The research study has found that Kathmandu has a low disaster resilience score with preliminary findings highlighting the susceptibility of critical infrastructure (i.e. roads, schools, hospitals, power, water supply) to natural hazards.

Effects of Soil Structure Interaction on Reinforced Concrete Framed Structures N. Dongol; s. Manandhar; P.M Pradhan
Lowland Technology International Vol 22 No 1 (2020): Lowland Technology International Journal - Special Issue on: Engineering Geology
Publisher : International Association of Lowland Technology

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This study proposes to highlight effects of soil structureinteraction on the Reinforced Concrete (RC) framedstructures. In this study, the seismic responses of thestructures are observed considering soil structureinteraction (SSI) from its actual soil condition. Here, twopreexisting structures are taken for the study. One isresidential building and the other is hospital building withtwo basements. Taking into account the actual soilcondition of each building site, this study provides idea onthe soil structure interaction on different kinds of buildings.Direct and substructure approaches are used to incorporatesoil structure interaction in the analysis. The properties ofsprings are calculated for different standard penetration test(SPT) values and springs are assigned for footing for thesubstructure approach. Entire soil-foundation-structuresystem is modelled and analyzed in single step for directapproach. Static analysis, response spectrum analysis andtime history analysis (THA) are done in order to find thevariations in natural periods, base shears and deflections ofthe structures by incorporating soil flexibility as compared tostructures with conventional fixed base.

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