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| 1 | Numerical analysis of surface subsidence in asymmetric parallel highway tunnels显示文摘Tunnelling related hazards are very common in the Himalayan terrain and a number of such instances have been reported. Several twin tunnels are being planned for transportation purposes which will require good understanding for prediction of tunnel deformation and surface settlement during the engineering life of the structure. The deformational behaviour, design of sequential excavation and support of any jointed rock mass are challenging during underground construction. We have raised several commonly assumed issues while performing stability analysis of underground opening at shallow depth. For this purpose, Kainchi-mod Nerchowck twin tunnels(Himachal Pradesh, India) are taken for in-depth analysis of the stability of two asymmetric tunnels to address the influence of topography, twin tunnel dimension and geometry. The host rock encountered during excavation is composed mainly of moderately to highly jointed grey sandstone, maroon sandstone and siltstones. In contrast to equidimensional tunnels where the maximum subsidence is observed vertically above the centreline of the tunnel, the result from the present study shows shifting of the maximum subsidence away from the tunnel centreline. The maximum subsidence of 0.99 mm is observed at 4.54 m left to the escape tunnel centreline whereas the maximum subsidence of 3.14 mm is observed at 8.89 m right to the main tunnel centreline. This shifting clearly indicates the influence of undulating topography and inequidimensional noncircular tunnel. | Ratan Das P.K.Singh Ashutosh Kainthola Suman Panthee T.N.Singh | 2017 | Journal of Rock Mechanics and Geotechnical Engineering2017，9，1： | 7 |
| 2 | Rock fragmentation control in opencast blasting显示文摘The blasting operation plays a pivotal role in the overall economics of opencast mines.The blasting subsystem affects all the other associated sub-systems,i.e.loading,transport,crushing and milling operations.Fragmentation control through effective blast design and its effect on productivity are the challenging tasks for practicing blasting engineer due to inadequate knowledge of actual explosive energy released in the borehole,varying initiation practice in blast design and its effect on explosive energy release characteristic.This paper describes the result of a systematic study on the impact of blast design parameters on rock fragmentation at three mines in India.The mines use draglines and shoveledumper combination for removal of overburden.Despite its pivotal role in controlling the overall economics of a mining operation,the expected blasting performance is often judged almost exclusively on the basis of poorly defined parameters such as powder factor and is often qualitative which results in very subjective assessment of blasting performance.Such an approach is very poor substitutes for accurate assessment of explosive and blasting performance.Ninety one blasts were conducted with varying blast designs and charging patterns,and their impacts on the rock fragmentation were documented.A high-speed camera was deployed to record the detonation sequences of the blasts.The efficiency of the loading machines was also correlated with the mean fragment size obtained from the fragmentation analyses. | P.K.Singh M.P.Roy R.K.Paswan Md.Sarim Suraj Kumar Rakesh Ranjan Jha | 2016 | Journal of Rock Mechanics and Geotechnical Engineering2016，8，2： | 5 |
| 3 | Stability investigation of road cut slope in basaltic rockmass,Mahabaleshwar,India显示文摘Slope failures along hill cut road slopes are the major nuisance for commuters and highway planners as they put the human lives at huge risk,coupled with immense monetary losses.Analysis of these vulnerable cut slopes entails the assessment and estimation of the suitable material strength input parameters to be used in the numerical models to accomplish a holistic stability examination.For the present study a 60 m high,basaltic and lateritic road cut hill slope in Mahabaleshwar,India,has been considered.A number of samples of both basalt and laterite,in their natural state were tested in the laboratory and the evaluated maximum,minimum and mean strength parameters were employed for the three cases in a distinct element numerical model.The Mohr-Coulomb failure criterion has been incorporated in the numerical model for the material as well as the joints.The numerical investigation offered the factor of safety and insights into the probable deformational mechanism for the three cases.Beside,several critical parameters have also been judged from the study viz.,mode of failure,factor of safety,shear strain rate,displacement magnitudes etc.The result of this analysis shows that the studied section is prone to recurrent failures due to the capping of a substantially thick layer of weaker lateritic material above the high strength basaltic rock mass.External triggering mechanisms like heavy precipitation and earthquake may also accelerate the slope failure in this area.The study also suggests employing instant preventive measures to avert the further risk of damage. | Ashutosh Kainthola P.K.Singh T.N.Singh | 2015 | Geoscience Frontiers2015，6，6： | 5 |
| 4 | Control of rock joint parameters on deformation of tunnel opening显示文摘Tunneling in complex rock mass conditions is a challenging task, especially in the Himalayan terrain, where a number of unpredicted conditions are reported. Rock joint parameters such as persistence, spacing and shear strength are the factors which significantly modify the working environments in the vicinity of the openings. Therefore, a detailed tunnel stability assessment is critically important based on the field data collection on the excavated tunnel's face. In this context, intact as well as rock mass strength and deformation modulus is obtained from laboratory tests for each rock type encountered in the study area. Finite element method(FEM) is used for stability analysis purpose by parametrically varying rock joint persistence, spacing and shear strength parameters, until the condition of overbreak is reached. Another case of marginally stable condition is also obtained based on the same parameters. The results show that stability of tunnels is highly influenced by these parameters and the size of overbreak is controlled by joint persistence and spacing. Garnetiferous schist and slate characterized using high persistence show the development of large plastic zones but small block size, depending upon joint spacing; whereas low persistence, low spacing and low shear strength in marble and quartzite create rock block fall condition. | Suman Panthee P.K.Singh Ashutosh Kainthola T.N.Singh | 2016 | Journal of Rock Mechanics and Geotechnical Engineering2016，8，4： | 3 |
| 5 | Analysis of groundwater level trend in Jakham River Basin of Southern Rajasthan显示文摘Groundwater accounts for about half of the water use for irrigation in India.The fluctuation pattern of the groundwater level is examined by observing rainfall replenishment and monitoring wells.The southern part of Rajasthan has experienced abrupt changes in rainfall and has been highly dependent on groundwater over decades.This study presents the impact of over-dependence on groundwater usage for irrigation and other purposes,spatially and temporally.Hence,the objective of this study is to examine the groundwater level trend by using statistical analysis and geospatial technique.Rainfall factor was also studied in groundwater level fluctuation during 2009-2019.To analyze the influence of each well during recharge or withdrawal of groundwater,thiessien polygonswere generated from them.In the Jakham River basin,75 wells have been identified for water level trend study using the Mann-Kendall statistical test.The statistics of trend analysis show that 15%wells are experiencing water level decline in pre-monsoon,while very low percentage of wells have such trend during post-monsoon season.The average rate of water level decline is 0.245 m/a in pre-monsoon and 0.05 m/a in post-monsoon.The aquifer recharge potential is also decreasing by year.it is expected that such type of studies will help the policy makers to adopt advanced management practices to ensure sustainable groundwater resource management. | Vinay Kumar Gautam Mahesh Kothari P.K.Singh S.R.Bhakar K.K.Yadav | 2022 | Journal of Groundwater Science and Engineering2022，10，1： | 2 |
| 6 | Eocene lignites from Cambay basin, Western India: An excellent source of hydrocarbon显示文摘In the present paper lignites from the Cambay basin have been studied for their hydrocarbon potential.The samples were collected from three lignite fieldse Vastan, Rajpardi and Tadkeshwar, and were investigated by petrography, chemical analyses and Rock-Eval pyrolysis. The results are well comparable with the empirically derived values. The study reveals that these ‘low rank C' lignites are exceedingly rich in reactive macerals(huminite t liptinite) while inertinite occurs in low concentration. These high volatile lignites generally have low ash yield except in few sections. The Rock-Eval data indicates the dominance of kerogen type-III with a little bit of type-II. The study reveals that the lignites of Vastan(lower and upper seams) and Tadkeshwar upper seam are more gas-prone while Rajpardi and Tadkeshwar lower seams are oil-prone. Further, the fixed hydrocarbons are several times higher than the free hydrocarbons. The relation between TOC and fixed hydrocarbon indicates that these lignites are excellent source rock for hydrocarbon which could be obtained mainly through thermal cracking. The empirically derived values reveal a high conversion(94e96%) and high oil yield(64e66%) for these lignites. | P.K.Singh V.K.Singh P.K.Rajak M.P.Singh A.S.Naik S.V.Raju D.Mohanty | 2016 | Geoscience Frontiers2016，7，5： | 1 |
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