http://localhost:8081/jspui/handle/123456789/27 Thu, 07 May 2026 03:31:50 GMT 2026-05-07T03:31:50Z http://localhost:8081/jspui/handle/123456789/20484 Title: PETROPHYSICAL AND MECHANICAL PROPERTIES OF ROCKS OF HIMACHAL AND GARHWAL HIMALAYAS Authors: Sahu, Anamika Abstract: Performance prediction in mining and civil engineering projects entails the characterization of rocks. The physical and mechanical properties of rocks are fundamental information for engineering purposes. These properties play a crucial role in categorizing and anticipating the behavior of rock mass with a view to the planning and execution of any geotechnical project such as underground structures, foundations on rocks, infrastructure works, tunnels, and dams. The Himalaya is a classic model of the structurally and tectonically complicated geo-environment and serve as a natural laboratory to examine diverse rock types and geological structures. Understanding these rocks is critical due to impending large-scale infrastructure developments in the Himalayas. However, examining the petrophysical and mechanical properties of rocks in a lab is difficult, expensive, laborious, and requires high-quality rock specimens. Consequently, indirect methods are promising for identifying these attributes. The petrographic parameters such as mineralogical composition and textural properties, intrinsically influence the physico-mechanical properties of rocks. This study aims to assess the physical and mechanical properties of Himalayan rocks and investigate the mutual dependence between these properties and the petrographic characteristics. Additionally, it examines the influence of seismic wave velocities on these parameters obtained through both in-situ and laboratory methods. The integrated analysis aims to comprehensively assess the impact of petrographic parameters and seismic wave velocities on the physico-mechanical properties of the studied rocks and to identify the dominant factors that affect them. Three sets of laboratory experiments were performed on the siliciclastic and carbonate samples collected from the study area. First, the petrographic test determined the mineral composition and textural characteristics of rocks. Second, the physical properties, including density, water content, porosity, and seismic wave velocities, were determined. Finally, unconfined compressive strength, Brazilian tensile strength test, and point load index test were done to evaluate their mechanical characteristics. Sandstone samples with varying textural characteristics and compositions were sampled from Himachal Himalaya and Garhwal Himalaya. Sandstone is one of the most abundant rock types found in nature and incorporates a wide range of rock types with varied mechanical, petrographic, and mineralogy characteristics. The substantial discrepancy in the petrographic and mechanical properties of sandstones is due to the inherent variability in mineral composition, grain size, shape variation, and non-uniform distribution of defects such as pores and microstructures. Mon, 01 Jul 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/20484 2024-07-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/20483 Title: Shallow shear wave investigation and its relation with litho-logs and delineation of geological structure Authors: Singh, Jyoti Abstract: Shear wave velocity (Vs) plays an important role in estimation of various engineering parameters. This thesis utilizes various methods to estimate one- and two-dimensional shear wave velocity profile and its application in development of regression relation based on the type of formation obtained at different depths and estimation of two-dimensional shear wave velcoity structure for lineation of shallow structures. The state of Uttarakhand in India which is the site of numerous ongoing projects is the locale of a major railway project from Rishikesh to Karnprayag by Rail Vikas Nigam Limited (RVNL). This region is highly susceptible to seismic activity, which is why earthquake-resistant design criteria is rigorously applied in construction practices. The shear wave velocity profiles at twenty-six different sites were estimated using both active and passive seismic exploration methods. The joint fit gives a one-dimensional velocity structure. The obtained shear wave velocity shows a consistent correspondence with bore log data and notably, there is a strong correlation between variations in shear wave velocity and lithology that is dependent on depth. It has been seen that shear wave velocity tends to rise with depth within similar formations. Data from twenty-four shear wave profiles have also been used from Garhwal Himalayas provided by RVNL to prepare a linear regression relation of shear wave velocity in different lithological formations with respect to depth of formation. The validation of this relationship is done by comparing observed and calculated velocity of shear wave at those sites that are excluded in the computation of the regression relation. A strong indication that the findings are reasonably well within the range of acceptability is provided by the Root Mean Square Error (RMSE) that was derived from the established relationship for the different types of lithology. The developed relation has been further validated by calculating shear wave velocity profile for borelog data obtained at two sites that are not included in the data set used for developing regression relations. Comparison of two velocity sections clearly shows that calculated velocity profiles match closely with that from the seismic survey and thereby establish the efficacy of the developed regression relationship. A major railway project, CharDham Project is undergoing in the state of Himachal Pradesh which is located in seismic zones IV and V in the seismic zoning map of India. Given the region’s susceptibility to seismic activity, it is always necessary to design structures according to the safety standards available in the country. Averaged shear wave velocity up to a depth of 30 meters (Vs30) is a crucial factor in designing earthquake-resistant structures in seismically active areas. In i this part, a study was conducted to determine in-situ Vs using active and passive methods at various locations covering the ongoing Bhanupalli-Bilaspur-Beri railway project. This facilitated earthquake hazard assessment and Vs30 calculations. Shear wave profiles for various stations have been derived using litho logs and compared to existing shear wave profiles and a strong agreement is found between these two data sets. When comparing two profiles, one developed from relationships and one from a seismic survey, a significant match is observed, confirming the value of the developed relationship. The application of a two-dimensional shear wave velocity profile for identification of the extent of rupture is made in this work for the location of Parwan Dam in the state of Rajasthan. Parwan Gravity Dam is under construction stage in the Jhalawar district of Rajasthan, India. A thin sub-vertical surficial fracture trending N 75°W to S 75°E has been observed in the foundation area of the dam. Geophysical techniques are utilized extensively in the field of civil engineering, and exploration geophysics for the assessment and construction of large-scale infrastructures such as dams. The combination of Multichannel Analysis of Surface Waves (MASW) techniques together with Electrical Resistivity Tomography (ERT) and Seismic Refraction Tomography (SRT) have been used to image the extent of shallow subsurface geological structures. These methods provide critical information about the subsurface conditions without the need of extensive drilling and excavation. These surveys have been carried out along several profiles in the longitudinal direction and along the transverse direction to the fault axis. A total of nine MASW profiles were conducted of which eight are transverse profiles and one is a longitudinal profile. A total of thirteen refraction and resistivity profiles were conducted of which nine were transverse profiles and four were longitudinal profiles. In this part of the thesis, the subsurface distribution of seismic wave velocity and electrical resistivity have been studied to identify any possible anomalous zone in bedrock and to detect the downward extension of surface fracture of brittle fault using the afore mentioned methods. The analysis of these survey results has investigated the vertical and lateral extent of the surface fracture of the fault. The analysis of the results indicates that a very tight and narrow fracture is present in the shallow subsurface. Mon, 01 Jul 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/20483 2024-07-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/20482 Title: EFFECT OF MEDIUM CHARACTERISTICS ON SH WAVE PROPAGATION Authors: Pandey, Mohit Abstract: The destruction at a location is due to the ground motion generated by an earthquake. However, the intensity of destruction may vary from location to location. This variation of intensity could be due to the amplification or deamplification of seismic waves propagated through the medium between the earthquake source and site location. Therefore, the propagating medium is a significant factor in the shaping of ground motion. The seismic waves released from the source are generally influenced by propagation path and local site effects. The work done in this thesis deals with the propagation path effect and local site effect. The shear waves (S-waves) which are produced during an earthquake are more disastrous because it create horizontal ground shaking which leads to the destruction of buildings and infrastructures. The understanding of propagation velocity and quality factor of SH helps in predicting the severity and distribution of seismic shaking, assessing seismic hazards, and constructing earthquake-resistant buildings that can withstand horizontal forces. The main objectives of this thesis are (i) to study the medium characteristics of Garhwal Himalaya and Kumaon Himalaya in terms of shear wave velocity (VS) and attenuation factor and (ii) to study the effect of shear wave velocity and topography on the SH wave propagation during an earthquake. In this work, the three-dimensional (3-D) S-wave attenuation tomography study has been done for the Garhwal Himalaya, Uttarakhand to understand the attenuation characteristics of S waves in the region. The strong ground motion (SGM) data collected from 19 earthquakes have been used for this purpose. The technique proposed by Hashida and Shimazaki (1984) which is later modified by Joshi (2006a, 2007) has been used for this purpose. The study shows that the anomalous zone of S-wave quality factor has been observed in the vicinity of the Alaknanda fault. The obtained results are compared with those obtained for the Kumaon Himalaya which has the same tectonic arrangements as that of the Garhwal Himalaya using similar technique by Kumar et al. (2015b). It has been found that the attenuation rate of seismic waves is higher in the Kumaon Himalaya in comparison to that in the Garhwal Himalaya. The regional frequency-dependent quality factor of order 𝑄𝛽 = 107𝑓0.82 has been developed for the Garhwal Himalaya using the results obtained from 3-D attenuation tomography. Mon, 01 Jul 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/20482 2024-07-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/20481 Title: MODELLING OF FINITE SOURCE AND MEDIUM CHARACTERIZATION Authors: Sharma, Saurabh Abstract: The modeling of a finite source and medium characterization plays a significant role in investigating the impact of earthquake on the observed ground motion at the surface. The strong ground motion at the recording site are heavily dependent on the size of earthquake source and the characteristics of medium through which seismic energy propagates. The main objective of this thesis is to investigate the effect of finite source of the strong ground motion (SGM) observed at the surface and the effect of finite medium on propagating seismic energy released during an earthquake. A finite source earthquake denotes a rupture that occurs across a defined area along a fault plane rather than occurring instantaneously at one point. As a result, knowing the mechanisms causing finite source earthquakes is essential for both minimizing human casualties and damage to property and enhancing our knowledge of the features of Earth's interior. Finite source modeling is needed to examine the spatial extent and the distribution of the slip along and across the fault plane accountable for an earthquake. Among various available simulation techniques, Modified Semi Empirical Technique (MSET) has evolved as an effective tool to simulate SGM records in recent years. In the present thesis, MSET has been tested to model the strong motion generation areas (SMGAs) and frequency dependent radiation pattern (FDRP) effect in modeling the finite rupture plane. In this context, the modeling of the finite source of the 2019 Hualien earthquake (Mw 6.1) has been successfully validated the proposed technique. The epicenter of the earthquake is 24.037°N, 121.65°E, and focal depth is 20 km. The rupture length and its downward extension for the Hualien earthquake are 32 km and 18 km, respectively. The highest Peak Ground Acceleration (PGA) of 379 cm/s2 for the E-W component and 515 cm/s2 for the N-S component for a station at 12 km distance from the epicenter. Both the spatiotemporal distribution of the earthquake's aftershocks and a visual examination of the recorded acceleration data indicate the presence of two SMGA within the finite fault plane responsible for this event. The finite SMGAs have been divided up into several sub-faults using the scaling laws. The simulation technique relies on the source parameters of the finite fault plane of the earthquake, specifically, two identified SMGAs, as the SGM is primarily generated by these SMGAs, necessitating their computation for modeling purposes. The source displacement spectra (SDS) is used to compute seismic moments of both SMGAs which are (4.80 ± 0.98) x 1017 Nm and (5.25 ± 0.93) x 1017 Nm, respectively, and the sum of these seismic moments is equivalent to the seismic moment of the whole rupture plane i.e. 1.05×1018 Nm. The observed acceleration ecordings at the surface need to be projected at the rock site using SHAKE91 as MSET simulates the records at the rock site only. The final modeling parameters like nucleation point, dip, and strike have been decided based on iterative forward modeling at a nearest station. Based on the iterative forward modeling and the minimum RMSEPGA i.e. root mean square error of PGA, the nucleation point is selected at the extreme left corner of the rupture planes of both SMGAs. The strike and dip of the rupture planes of both SMGAs are selected as N215.5° and 45°, respectively. A comparison has been made between the PGA calculated using simulated accelerograms and that acquired from accelerograms observed at stations located within a 100 km radius around the epicenter. Additionally, the PGA distribution trend is presented with respect to the epicentral distance and compared with the PGA derived from the attenuation relation provided by Lin and Lee (2008). The contour plot trend of the N-S and E-W components, both simulated and observed suggests a northward directivity effect caused by the rupture, consistent with the findings by Lee et al. (2020). Mon, 01 Jul 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/20481 2024-07-01T00:00:00Z