Application of Observational Method in the Successful Construction of Underground Structures, Sardar Sarovar (Narmada) Project, Gujarat, India

The Sardar Sarovar (Narmada) underground powerhouse is located in Deccan Basalt flows in the lower Narmada valley in Gujarat state. These flows are intruded by dolerite dykes and sill. Basalt flows and dolerite rocks are considered good tunneling media for locating underground structures. Therefore, initial designing of supports was done considering good rock mass conditions. However, during construction numerous geotechnical problems were encountered necessitating review of support system. Rock falls and collapses were observed in tunnel sections passing through dolerite dykes and sills. Cracks were observed in the walls of the powerhouse cavern. During progressive excavations back analysis was done to know the causes of distress in rock mass and structures The ‘Observational Method’ adopted during construction resulted in the safe execution of structures by timely modification and installation of adequate support system

Rock Mass Evaluation of the Sardar Sarovar (Narmada) Dam and Underground Powerhouse, India

Geotechnical evaluation of the 163 m high concrete gravity Sardar Sarovar (Narmada) dam, under construction, and 1200 MW underground powerhouse (210m x 23m x 57.5m) and its ancillary structures has been done. The dam and powerhouse sites are occupied by basalt flows underlain by infra-trappean sedimentary rocks (Bagh beds) intruded by basic dykes. The area is structurally complex and seismically active. Intra-formational shears and sub-horizontal to low dipping weak layers like red bole, tuff, argillaceous sandstone having low values of shear parameters posed the problem of sliding stability of dam blocks. Concrete shear keys were provided as one of the remedial measures. Differential settlement was apprehended in the foundation of dam having varying physicoengineering properties and rock mass characteristics. Reinforced concrete mats were provided to treat the weathered and sheared rock mass and 34.5m deep reinforced concrete plug to prevent differential settlement of dam blocks located on river channel (dam base) fault. The horizontal seismic coefficient adopted for the dam is 0.125g. The construction of 1200 MW underground powerhouse located in basalt is nearing completion. During progressive excavation of the machine hall (cavern) cracks were observed in the 57.5m high shotcreted walls. Additional longer rock bolts/ cables/ tendons were provided as remedial measures. Draft tube and exit tunnels are passing through dolerite rocks dissected by chlorite-coated joints and slaked rock zones. Rib supports were introduced after observing behaviour of the rock mass and collapses in part of these tunnels

Assessment of Groundwater Hazards in a Coastal District of Gujarat, India

Jamnagar district of Gujarat is having 355 km long irregular coast line. The district is bounded by Gulf of Kachchh in the north and Arabian Sea in the west and southwest. The precipitation in the area is low and climate is semi arid. Rivers flowing in the area are ephemeral. Ground water occurs in unconfined and semi-confined state. Major central part of the area is occupied by Deccan basalt, western part by marine Tertiary rocks, northern and western coastal area by Quaternary sediments. In general, ground water in Deccan basalt is fresh whereas in Tertiary and Quaternary sediments it is brackish due to inherent salinity as well as sea water intrusion. Miliolite limestone in this area forms good aquifer. Groundwater hazards in the area are mainly related with the inherent salinity of rocks/ sediments, sea water ingress in the coastal area and chemical pollution. Brackish ground water, toxic element (Pb, Ni) and radicals (SO4--, NO3-, Cl- and Fluoride) zones have been identified and delineated based on the integrated GIS study. About 181 villages of the district are affected by high TDS, 39 villages by high Fluoride and 2 villages both by high TDS and Fluoride

Geotechnical Problems and Treatments of Weathered Rock Seams Occurring in the Foundation of Karjan Dam, Western India

The Karjan dam is located on the Deccan Basalt flows of Cretaceous - Eocene age in the Narmada valley in Gujarat state. A characteristic feature of the basalt flows in this area is conspicuous presence of a number of sub-horizontal weathered rock seams posing the foundation problems of settlement, sliding and seepage. Concrete shear keys have been provided to increase the sliding stability of dam blocks besides other remedial measures. Additional curtain grouting has been done after completion of the dam to reduce seepage

Geotechnical Assessment and Evaluation of the Impact of Kachchh (Bhuj) India 2001 Earthquake

Intraplate earthquakes are ongoing activity in the Kachchh region. The area is seismically active and falls in Zone V of the seismic Zoning Map of India. The devastating Bhuj (Kachchh) Earthquake of MS 7.6 occurred in this zone on 26th January, 2001 causing severe damage to civil engineering structures and loss of human life. The surface manifestations of deformation of this earthquake include fractures/ fissures, lateral spread, slump, subsidence, upheaval, sand blows and craters. Bhuj Earthquake has caused considerable damage to earth dams lying in isoseist VIII and above in Kachchh. Damages to dams are in the form of longitudinal and transverse cracks, differential settlement, slumps/ slide, displacements and in some cases leakage. A review of the available geological, seismological and geotechnical data have been done to asses the impact of Bhuj Earthquake and subsequent seismic events in the area on ground deformation and engineering structures. Main cause of the ground deformation and damage is liquefaction of the soil under seismic shaking. Tectonic influence on the development of fissures/ cracks on the ground as well as on the earth dams has been observed

Geotechnical Problems of the Underground Excavation in the Deccan Basalts Sarovar (Narmada) Project, Gujarat, India

The Sardar Sarovar (Narmada) Project, Gujarat State envisages the construction of an underground power house (6x200 MW) and its ancillary structures in the Deccan basalt. The basalt lava flows in the area are intruded by dolerite dykes and sills and dissected by fractures, shears and faults. These features have posed varied geotechnical problems like block falls, wedge failures, roof collapses and water seepage during the excavation of machine hall, access tunnel, draft tube tunnels and exit tunnels. The adequacy of support system designed on the basis of Barton’s and Bieniawski’s rock mass classification is constantly monitored and reviewed from time to time. The main power house cavern (210x23x58m) is being entirely supported by rock bolts and shotcretes with wiremesh. In the shotcreted upstream and downstream faces of the power house cavern cracks for maximum height of 22 m has been observed and are under evaluation. The rib supports have been introduced in tunnels passing through slacked zones in dolerite dykes and sills traversed by faults and shear zones

Local Values in Governance: Legacy of Choho in Forest and School Management in a Tamang Community in Nepal

The political modernization in Nepal accelerated since 1951 when the country changed its course owing to a popular movement that was acclaimed as the beginning of democracy in the country. However, the governments continued cultural and political homogenization.  This has been so in the case of local governance practices as well. Modern governing structures/institutions are guided by the state formed policies and elite-based power structures despite the fact that different ethnic groups in Nepal have their own traditional self-governance systems. In this context, this article unfolds the inheritance of traditional practices of the Tamang community (one of the major ethnic groups of Nepal), in a village, in the district adjoining Kathmandu valley, within the modern structures of governance of forest and school management systems. The paper argues that there is a legacy of the traditional institution, the Choho, though the system of Choho itself has now largely disappeared. This paper, based on ethnographic fieldwork, presents the accounts of Choho and examples of how the particular norms, values, beliefs, and practices are still in practice challenging and denying the modern/state formed mechanisms of governing the forests and schools in the village. The paper further argues that given the modern governance system, the traditional souvenir exchange practice that was rooted in the notion of honour and respect has now shifted towards the practice of giving and receiving gifts based upon the principle of reciprocal benefits that could be described as a bribe

Routing scheme for macro mobility handover in hierarchical mobile IPv6 network

Significant problems in basic mobile IPv6 occur due to its inability to support micro-mobility because of long delay and high packet loss during handover. Hierarchical mobile IPv6 (HMIPv6) as an extension of basic Mobile IPv6 solves the problem by separating the handover management to macromobility and micro-mobility. HMIPv6 introduced a new protocol element called Mobility Anchor Point (MAP) to manage the mobility. HMIPv6 can reduce the delay and the amount of signaling during handover. However the protocol still cannot meet the requirement for traffic that is delay sensitive such as voice especially in macro mobility management. Duplicate address detection and the transmission time for the handover operation could cause high handover delay

Fast handover algorithm for hierarchical mobile IPv6 macro-mobility management

Mobile lh.6 (MIPv6) has some limitations due to long delays and signaling load during handover operation. Hierarchical Mobile IPv6 (HMIPv6) is the extension of MIPv6 that is designed to reduce the signaling load and to improve handover speed of MIPv6 by splitting the mobility management into macro and micro mobility management schemes. However HhfIPv6 only improves micro mobility problem where the signifcant delay still occurs in the macro mobility management because the handover algorithm is similar with the MIPv6 environment, This paper proposes a new fast handover algorithm that overcomes the limitations in Mobile MIPv6 and its extension HMIPv6. Our design objective is to re-establish the communication traffic flow quickly and to minimize the service disruption delay that occnrs during handover process in a macro mobility environment. This handover algorithm is based on the modification of the HMIPv6 protocol using the multicast technique concept. This algorithm will enable the mobile node to receive packet faster than HMIPv6 protocol during handover, seamlessly and transparently. Keywords: Mobile lPv6, HMPv6, Hondover. Mufticart Schem

Solubility Enhancement of Steviol Glycosides and Characterization of Their Inclusion Complexes with Gamma-Cyclodextrin

Steviol glycosidesrebaudioside (reb) A, C and D have low aqueous solubilities. To improve their aqueous solubilities, inclusion complex of steviol glycosides, reb A, C and D and gamma cyclodextrin were prepared by freeze drying method and further characterized by means of differential scanning calorimetry, Fourier transform infrared spectroscopy and Raman spectroscopy. The effect of gamma cyclodextrin on chemical shifts of the steviol glycosides was also studied in proton NMR experiments as well as in solid state 13C CP/MAS NMR experiments. These results indicated that the steviol glycosides were clearly in inclusion complex formation with the gamma cyclodextrin which also results in solubility enhancement of these steviol glycosides. Phase solubility studies showed that amounts of soluble reb A, C and D increased with increasing amounts of gamma cyclodextrin indicating formation of 1:1 stoichiometric and higher order inclusion complexes