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The findings of an extensive experimental research study on the usage of nano-sized cement powder and other additives combined to form cement–fine-aggregate matrices are discussed in this work. In the laboratory, dry and wet methods were used to create nano-sized cements. The influence of these nano-sized cements, nano-silica fumes, and nano-fly ash in different proportions was studied to the evaluate the engineering properties of the cement–fine-aggregate matrices concerning normal-sized, commercially available cement. The composites produced with modified cement–fine-aggregate matrices were subjected to microscopic-scale analyses using a petrographic microscope, a Scanning Electron Microscope (SEM), and a Transmission Electron Microscope (TEM). These studies unravelled the placement and behaviour of additives in controlling the engineering properties of the mix. The test results indicated that nano-cement and nano-sized particles improved the engineering properties of the hardened cement matrix. The wet-ground nano-cement showed the best result, 40 MPa 28th-day compressive strength, without mixing any additive compared with ordinary and dry-ground cements. The mix containing 50:50 normal and wet-ground cement exhibited 37.20 MPa 28th-day compressive strength. All other mixes with nano-sized dry cement, silica fume, and fly ash with different permutations and combinations gave better results than the normal-cement–fine-aggregate mix. The petrographic studies and the Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) analyses further validated the above findings. Statistical analyses and techniques such as correlation and stepwise multiple regression analysis were conducted to compose a predictive equation to calculate the 28th-day compressive strength. In addition to these methods, a repeated measures Analysis of Variance (ANOVA) was also implemented to analyse the statistically significant differences among three differently timed strength readings.

In the Kachchh Mainland, the Jumara Dome mixed carbonate-siliciclastic succession is represented by the Jhurio and Patcham formations and siliciclastic-dominating Chari Formation （Bathonian to Oxfordian）. The Ju- mara Dome sediments were deposited during sea-level fluctuating, and were interrupted by storms in the shallow marine environment. The sandstones are generally medium-grained, moderately sorted, subangular to subrounded and of low sphericity. The sandstones are mineralogically mature and mainly composed of quartzarenite and subar- kose. The plots of petrofacies in the Qt-F-L, Qm-F-Lt, Qp-Lv-Ls and Qm-P-K ternary diagrams suggest mainly the basement uplift source （craton interior） in rifted continental margin basin setting. The sandstones were cemented by carbonate, iron oxide and silica overgrowth. The Chemical Index of Alteration values （73% sandstone and 81% shale） indicate high weathering conditions in the source area. Overall study suggests that such strong chemical weathering conditions are of unconformity with worldwide humid and warm climates during the Jurassic period. Positive correlations between A1203 and Fe203, TiO2, Na20, MgO, K20 are evident. A high correlation coefficient between A1203 and K20 in shale samples suggests that clay minerals control the major oxides, The analogous con- tents of Si, A1, Ti, LREE and TTE in the shale to PAAS with slightly depleted values of other elements ascribe a PAAS like source （granitic gneiss and minor mafics） to the present study. The petrographic and geochemical data strongly suggest that the studied sandstones/shales were deposited on a passive margin of the stable intracratonic basin.

Rock mass characterization of Utari dam in Lalitpur district of Uttar Pradesh was done to identify different stability classes of rock mass. For better stability of Utari dam, foundation conditions were carefully studied by detailed field investigations of the site supplemented by laboratory tests. During feasibility and preliminary stages, rock mass characterization of slopes was conducted to identify the vulnerable zones of failure. Rock mass characterization was done by compilation of information obtained from intact rock as well as from rock mass to determine its grade and long term slope stability of the site. On the basis of Rock Mass Rating (RMR) and Geological Strength Index (GSI) slope stability is identified which lies under good quality rock mass. Kinematic analysis was conducted to find out the probability for different types of structurally controlled slope failure. Microscopic analyses were conducted to identify the degree of chemical alteration of feldspar. Clay formation by sericitization along joint planes is harmful for the stability of dam structure. Remedial measures must be taken to reduce the extent of chemical alteration. Granitoids at dam site forms a compact and stable foundation consisting of four sets of joints in which two sets were prominent which are dipping on the upstream side of the dam which reveals good condition on the dam site as leakage from reservoir will be minimum and least up-thrust on the dam structure. Copyright 2016 Geological Society of India

The Paleoproterozoic phosphorites constitute an economically significant component of the Sonrai basin of Lalitpur district. These are associated with ferruginous shale, ironstone, limestone and quartz breccia. Petro-mineralogical studies of samples of the phosphorites, using X-ray diffractometry and scanning electron microscopy, reveal that the collophane (carbonate-fluorapatite) is the dominant phosphate mineral. Calcite, dolomite, quartz, mica and haematite are the dominant gangue constituents. The phosphate minerals occur as oolites mutually replaced by carbonate and silica. The presence of iron oxides has been found in most of the thin sections. There is meagre evidence of organic matter in the form of filaments of microbial phosphate laminae in the samples of phosphorite. The mineral assemblages, their texture and various forms in these phosphorites may be due to some environmental vicissitudes followed by replacement processes and biogenic activities.

The sandstones of the Ridge and Athleta members of Chari Formation (Callovian-Oxfordian) exposed at Jara have been analyzed for their petrographical and geochemical studies. Texturally, these sandstones are medium to coarse grained, poorly to well sorted, sub-angular to sub-rounded, and show low to medium sphericity. These sandstones were derived from a mixed provenance including granites, granite-gneisses, low and high-grade metamorphic, and some basic rocks of Aravalli range and Nagarparkar massif. The petrofacies analysis reveals that these sandstones belong to the continental block and recycled orogen tectonic regime. The studied sandstones are modified by paleoclimate, distance of transport, and diagenesis. Mineralogically and geochemically, sandstones are classified as quartzarenite, subarkose, arkose, sublithic arenite, and wacke, respectively. The A-CN-K ternary plot and CIA, CIW, PIA, and ICV values suggest that the similar source rocks suffered moderate to high chemical weathering under a hot-humid climate in an acidic environment with higher P CO 2 . Generally good to strong correlations between Al 2 O 3 and other oxides in these sediments indicate clay mineral control. The K 2 O/Na 2 O versus SiO 2 diagram indicates that the studied samples occupy passive margin fields but the SiO 2 /Al 2 O 3 versus K 2 O/Na 2 O plot suggests that the Athleta Sandstone and Ridge Sandstone fall within the passive margin field, while Ridge Shale falls within the active continental margin field.

Transportation tunnels are strategic parts of all urban development projects. Challenges are faced while selecting the excavation techniques and support types in these underground constructions. Hence, sufficient information and knowledge are required while designing the shield support system in soft ground tunnelling. In this study, a two-dimensional plane strain finite element simulation of a tunnel having 350-mm thick reinforced concrete liner has been carried out. The effects of soil stratification, degree of saturation, and seismic loading have been considered for the analyses. Mohr-Coulomb’s constitutive model has been adopted to simulate the linear elastic-plastic behaviour of soil in static analysis. Furthermore, the dynamic response of horizontal shear waves (S-wave) has also been investigated on the tunnel’s model. It was observed numerically that the stresses and deformation reduced to 15% and 30% respectively when sandy silt (SM), soil layer moved towards liner in stratification analysis. The tangential and radial stresses increased by 24% and 35%, respectively, due to groundwater presence above the crown. Moreover, vertical and horizontal settlements have increased exponentially that led to a reduction in the shear strength of soil due to variation in water level. Also, ovaling (egging) deformation was observed in the liner due to the propagation of seismic shear waves at the base of the tunnel.

The present research work is investigating the behavior of reinforced concrete (RC) cylinders after exposure to elevated temperatures. Reinforcement was done by using the longitudinal bars with closely spaced lateral ties (i.e. confinement). Experiments were carried out on the RC cylinders subjected to a single heating–cooling cycle of elevated temperature ranging from 200 to 800 °C with an interval of 200 °C for a holding time of 3 h. The crack patterns, color change, spalling and residual load carrying capacity of RC cylinders after exposure to elevated temperature have been observed. The residual load carrying capacity of RC cylinders has been compared with the load carrying capacity of control specimens at ambient temperature. The percent reduction in residual load carrying capacity after heating at 200 °C, 400 °C, 600 °C, and 800 °C temperature is 24.5%, 38.8%, 63.3%, and 83.7% respectively as compared with the load carrying capacity at ambient temperature. The finite element modeling (FEM) has been carried out to observe the thermal stresses and strains induced in the confined RC cylinders. Experimental observations of thermal strains and those obtained by the numerical model showed a good agreement. The scanning electron microscopy (SEM) has also been carried out to study the changes in the microstructure of confined high grade concrete and it was observed that the micro-cracks and pores increase and become more pervasive with increase in temperature.

Slope stability of mine slopes is often associated with safety and economics during excavation. Sandstone is excavated from Rasulpur area of Fatehpur Sikri in Uttar Pradesh for the purpose of crushed, decorative and dimension stones. In the present paper an attempt has been made to characterize the rock slope faces into different stability classes. Characterization is based on geological and geotechnical parameters recorded on the outcrop during field investigation and supplemented by geomechanical properties by the laboratory test for strength of the rock intact. SMR Geomechanics classification is used to identify the stability class and remedial measures are also suggested to reduce any possible hazard. Kinematic analysis of slope was also investigated to determine the probability of any possible structurally controlled failure. On the basis of SMR Geomechanics calculations slope under investigation lies under good stability class i.e. 2a and 2b. Installation of nets during excavation can be done and for better safety spot and systematic rock bolting can be done. Kinematic study reveals that toppling failures may occur, special care must be given to the joint set which can trigger toppling failure. Copyright 2016 Geological Society of India

Underground rock tunnels have been an integral part of human civilization, since several decades. The construction and continuous use of these underground structures have become an essential part of metro cities. Moreover, tunnels and other underground utility construction has an important role as strategic structures, especially in defense sector. Due to these reasons, terrorists and other anti-social activities have targeted tunnels to inflict damage by using explosives that cause blasts. Therefore, tunnels and other underground structures should be design and strengthened against blast loading. In this paper, an attempt has been made to understand the behaviour of three different rock tunnels in commonly found three different rocks i.e., Granite, Basalt and Quartzite. The geometry of the finite element model has been kept constant for each rock type. The nonlinear elastoplastic behaviour has been simulated through Mohr–Coulomb, Johnson–Cook and Concrete-Damage-Plasticity constitutive material models for rock, reinforcement and concrete liners respectively. In addition, the 100 kg of trinitrotoluene (TNT) explosive has been considered throughout the paper for different cases. The advanced method of modelling, i.e., coupled-Eulerian–Lagrangian method has been considered for modelling TNT and air inside the tunnel to simulate internal blast loading. Deformation, shock wave velocity, acceleration, pressure, stress, strain energy and damage are the different parameters extracted, analyzed and discussed in aftermath of internal blast loading effect on rock tunnel. The finite element modelling has been validated through experimental and numerical results presented in the published literature. The finite element software Abaqus has been used for the simulation of internal blast loading in rock tunnel.

Sandstones from the shale-sandstone association of Permo-Carboniferous sequence of the Kanawar Group of Spiti region are takenup for detailed petrographic and geochemical investigation. Compositionally, they are quartz-arenite, sub-litharenite and subarkose. Their chemical index of alteration (CIA) values range from 53 to 78 i.e., indicating low to intense chemical weathering. The point counts shows the presence of quartz as a dominant framework mineral with varying amounts of rock fragments (mainly chert, phyllite, gneissic components) and feldspars andindicate cratonic interior and recycled orogenon the Qt (quartz)-F (feldspar)-L (lithic fragments) triangular diagram, suggesting their derivation mostly from stable cratons. The integrated petrographic and geochemical studies suggest that sandstones from the Tethys Himalaya, Spiti region, are derived probably from a felsic (granitic) dominant source occurring to the south of the basin.