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A systematic correlation is established between the axial load-carrying capacity of the socketed piles and empirical methods. The axial load-carrying capabilities were calculated with the help of pile load tests for ten single piles in Navi Mumbai, India. Pile load tests were carried out to evaluate the skin friction and base resistance in overlying soil and rock. The test results of axially loaded bored piles socketed into the rock are mentioned in this paper. The pile socket involved rocks of various strengths such as gypsum, limestone, and basalt. In reality, axial capacity is calculated from skin friction of the pile, which occurs owing to a very small settlement in the rock socket. The unconfined compressive strength of the rock is collected from the laboratory test. The load-bearing capability of the socketed piles is determined using several empirical methods, which are usually evaluated by a back-assessment of the in-situ pile load test. However, the significant load-carrying capacity values derived from empirical correlations are found to be reasonably good compared with those estimated from pile load tests. [ABSTRACT FROM AUTHOR]

Sustainable development goal 6: clean water and sanitation—could be a big challenge for water-stressed India. Use of non-potable water for concrete production can contribute largely towards this goal. Scattered experimental studies on concrete mixed with non-potable water having different pH, were collated to prepare a pan-Indian database. Using this data, probability of code compliance of Indian concrete for varying ranges of pH value of mixing water, within the limits permitted by the Indian code (6–8.5), were estimated for the first time in India. A bootstrap-based re-sampling approach was employed for this purpose. The results indicated that fulfilling the 28-day strength requirements would possibly concurrently fulfill similar stipulations for 7-day strength for Indian concrete mixed with non-potable water of varying pH. However, the probabilities of meeting the Indian code requirements were between 54%-66% for pH ranges starting from 6; and between 66%-85% for others (95% confidence). Considering the entire range of pH (6–8.5), this probability was 66% for 28-day and 72% for 7-day (95% confidence). Probabilistic approach for examining the strength/setting time compliance, along with inclusion of 7-day strength as well as durability aspects in future experiments would help to promote use of non-potable sources of water and reduce use of freshwater for mixing concrete in India. [ABSTRACT FROM AUTHOR]

The effective exploitation of hydrocarbon from basement reservoirs requires an understanding of geomechanical parameters. Uniaxial compressive strength (UCS), Young's modulus (E), and Poisson's ratio (ν) are key attributes in addressing a range of geomechanical problems. The rock texture, which is chiefly dependent on the size, shape, orientation of grains, and their spatial distribution in the sample, provides valuable information about rock strength. In this study, we present the dependence of UCS on the rock texture in igneous and metamorphic basement rocks of western offshore India. A texture coefficient (TC) was calculated to quantify the rock texture, and an empirical relationship between TC and laboratory-derived UCS was standardized, which was then used to calculate UCS from TC. We also standardized new equations to calculate UCS from compressional (Vp) and shear wave (Vs) velocities using non-destructive technique (NDT). The static and dynamic values of E and ν were measured in laboratory, and new relations were standardized to calculate static from its dynamic equivalents. The results show that the dynamic values for ν are higher (approx. 22%) than the static values for all basement samples, whereas E exhibits a positive and a negative correlation between the dynamic and static values for mafic and felsic basement rocks, respectively. This study addresses the importance of rock texture in determining the UCS and the other associated elastic and geomechanical properties, which in turn will help in wellbore instability studies, planning hydrofracturing designs, and rock strength analysis of unconventional basement reservoirs of western offshore basin. [ABSTRACT FROM AUTHOR]

In general, all countries in the world use ordinary Portland cement concrete for the construction purpose; this ordinary Portland cement (OPC) gives good mechanical properties and durability to the buildings. The binder cement and the filler aggregate are the ingredients widely used in the process of concrete. Natural resources are used to extract both filler and binder elements. In India, the fast-growing sectors like infrastructure, smart cities development, and real estate consume concrete in large quantity. Also, India is the second largest cement manufacturer in the world. The need of cement is increasing day to day, even though the country is manufacturing the cement more than the required demand. In an average, the cement manufacturing industries produce 6% of CO2; for example, if industries produce 1 tonne of cement, they also emit 1 tonne of CO2. This brings us environment changes and produces more pollution to the country. To handle this situation, after many research, geopolymer concrete has been developed. Geopolymer concrete (GC) is all about mixing of source materials to the alkaline solution. Fly ash (FA) that is collected from the power plant is used in GC. The FA-based GC gives more strength when compared to the normal OPC concrete. Under ambient and steam curing, the compression, flexural strength, and tensile strength of FAGC and steel-reinforced geopolymer (SFGC) were tested and results were compared with normal concrete. FAGC mix proportions were studied under different ratios for sodium hydroxide and sodium silicate with 10 M. When compared with normal cement, the strength given by FAGC achieved good strength under ambient temperature. FAGC was further tested for the acid, sulfate, water absorption, and sorptivity test and compared with OPC concrete. [ABSTRACT FROM AUTHOR]

The Barakar coal measures of Rampur Shaft Block, Godavari Valley Coalfield, Telangana, India, comprise about 190 m of fluviatile sequence of the Permian age with several minable coal seams of which the King Seam is laterally extensive and is up to 13 m thick. About 119 geophysical logs of the block were analyzed and correlated to identify the depositional architecture of the seam and its splitting behavior to aid safer and more productive mining. Coal seams and their associated lithologies are interpreted using various combinations of cross plots and frequency distribution histograms obtained from digital log data. The cross-sections and the isopach maps constructed during the present study indicate that the central region of the block constituted an inter-fluvial sediment bypass zone protected from the clastic interruption, facilitating the preservation of the entire King Seam as a single thick coal seam, which is splitting towards south and north. The soft and weak shale beds of a typical floodplain constitute the roof and floor rocks of various coal benches along the zones of merging. These rock types have a Uniaxial Compressive Strength (UCS) and Geophysical Strata Rating (GSR) of 3 MPa and 15–30, respectively. At the zones of splitting, the splits comprise bed load sandstone deposits of a braided fluvial system having a UCS of 3 to 10 MPa with a GSR range of 30–45. Thus, the present paper highlights the applicability of geophysical logs in bringing out the depositional geometry of the King Seam and explains its implications on the mining conditions. [ABSTRACT FROM AUTHOR]

The July 12, 2016 Tombinoutek landslide along state highway between Imphal and Jouzangtek village, Manipur, India affected the road section for a stretch of ∼475 m. The research aimed at finding the combined effects of topography, lithology and structural attributes of the landslide. Detailed geodetic survey was carried out using drone supported by ground control points obtained by total station survey. Base map with 5 m contour intervals, slope and aspect maps prepared; critical slope is between 45° to 60°. Geological studies have shown occurrence of intercalated sandstones and dissected shale, disturbed by five prominent joint sets which play an active role in the initiation of the landslide through plane and wedge failures. Geotechnical analyses of sandstones indicated strong compressive strength ranging between 80 and 97 Mpa, and tensile strength of sandstones and shales between 17 and 20 Mpa and 2.62 and 3.27 Mpa respectively. Soil analyses showed plasticity index (IP, percentage) of 10.66, and liquid limit (WL%) of 32.5. Average soil porosity is 80%. Liquidity index of -1.208 indicates relatively stable condition under dry condition. Plasticity index of 10.66 lies in the CL field, close to the boundary between low plasticity and medium plasticity. Sandstones show fair rock RMR with class IIb stable SMR, and shales show poor rock RMR with class IIIb partially stable SMR. [ABSTRACT FROM AUTHOR]

Evidence of frictional melting in the form of pseudotachylite is innumerably found along the Gangavalli fault zone (GFZ), southern India. Such catastrophic deformation influences the strength of rock masses across the fault zone. In this paper, we have investigated the strength variation in fault zone rocks during post-seismic deformation. The experimental study suggests that the average uniaxial compressive strength (UCS) for pseudotachylite hosting charnockite (i.e., Pt-charnockite) is almost double (45.58 MPa) as compared to the pseudotachylite devoid charnockite (i.e., D-charnockite) of 24 MPa. The melt associate seismic deformation shows high stress drop due to melt lubrication at the fault interface and simultaneously produced numerous fractures in the rock. We have determined the stability and denseness of both rock types using acoustic emission (AE) technique that remarks a distinct difference in AE signatures. The analysis indicates a more stable and dense Mogi type-III signature for post-seismic deformed rocks that are assisted by pseudotachylite melt. However, negligible AE energy is observed in the D-charnockite. We proposed that the melt-assisted seismic deformations are more inhibitable to reactivate the slip surfaces than the conventional earthquake-deformed rock having no melting phenomenon and therefore, pseudotachylites enhance the strength of fault zone rocks during post-seismic deformation. [ABSTRACT FROM AUTHOR]

The study considers the impact of the degree of weathered material constituting the sedimentary rocks on the strength of the Lower Gondwana coal measure rocks. The dependence of the strength of primary rocks on the alteration indices has been previously studied, but it is unknown for secondary/sedimentary rocks. Therefore, in this paper, Lower Gondwana coal measure rocks (sandstone and shale) from the most productive coalfields of India, the Barakar and Raniganj coalfields, have been studied geochemically and geomechanically to find out their correlation. Geochemically, the study revealed that an arid, non-marine, and deltaic depositional environment prevailed during the sedimentation of Barakar and Raniganj Formations. The provenance was deduced to be mafic igneous. It was also deduced that the Lower Gondwana sandstone is clay-rich, and the sandstone samples fall in the shale field in the chemical classification scheme for terrigenous clastic sediments. The weathering indices, along with the uniaxial compressive strength (UCS) of the Barakar and Raniganj Formation coal measure rocks, have been assessed. The dependence of UCS on the weathering indices has been evaluated, and positive relationships were obtained. [ABSTRACT FROM AUTHOR]

Dried sandstone slurry (DSS) is generated during mining and processing of stone and is accounted as man-made hazardous waste material, contaminating the environment in nearby areas. The use of DSS in self-compacting concrete (SCC) was studied by partially substituting pozzolana Portland cement at different percentages. This represents the recycling element of the 3 R's of the environment (reduce, reuse and recycle). Mechanical and permeability properties were evaluated and the microstructure of SCC analysed with respect to a control mixture which is without sandstone slurry. Mechanical and permeability parameters were found to relate each other. With increased replacement of DSS, the porosity and hence the sorptivity coefficient of SCC also increased and its compressive strength decreased. The higher porosity caused a significant increment in the depth of carbonation. Scanning electron microscope (SEM) and X-ray diffraction (XRD) showed decreased calcium-silicate-hydrate (C–S–H) gel formation as the replacement percentage of DSS increased. This, along with the increased porosity and permeability, degraded the mechanical properties of SCC. The rapidly developing construction sector in India must meet the following indispensable criteria: low environmental impact at improved structural performance, economy and speed of construction. Utilization of sandstone waste is highly recommended from the above viewpoint. [ABSTRACT FROM AUTHOR]

Paste backfilling is an incipient underground mine backfill technology in India. It facilitates maximum use of mill tailings with enhanced stability of the underground workings and minimises rehandling of water, as well as provides bulk disposal of mining solid waste. Binder type and dosage plays an important role in paste backfill performance. This paper highlights environmentally friendly utilisation of solid wastes like lead–zinc mill tailings and lead–zinc smelter fuming furnace slag (FFS) as paste backfilling for an underground metalliferous mine. Various experiments were conducted to study the effect of use of FFS as a fractional replacement for ordinary portland cement (OPC) in paste backfilling. The physico-chemical properties of both the lead–zinc mill tailings and fuming furnace slag (FFS) have been examined. In the first set of experiments, raw slag (FFS) was used for paste backfill preparation and experimentation for uniaxial compressive strength (UCS) development, whereas in the second set of experiments, FFS was crushed to -75 μm (80 wt%) and used for the study. Multiple regression analysis of strength development was also conducted up to fifth order. The regression analysis is in accordance with the strength development and justifies the significance of OPC, crushed fuming furnace slag (CFFS) and waste chemistry on the strength gain with curing time. Use of crushed fuming furnace slag as OPC replacement in paste backfill showed encouraging results of strength development in contrast to raw FFS. Also, the economic analysis revealed that the paste backfilling cost per tonne reduced significantly with slag replacement in the binder phase. [ABSTRACT FROM AUTHOR]