Ramana, G. V., Pathak, S., & Kumar, N. (2013). Selection and interpretation of shear strength parameters for weak phyllites. In Kwasniewski &  Lydzba (Eds.), Rock mechanics for resources, energy and environment: ISRM–International Symposium: EUROCK-2013 (pp. 331–336). Wroclaw, Poland: Taylor & Francis Group, London.

Hydroelectric power projects are pollution free and renewable sources of energy. These projects involve the construction of dams across the flowing stream ofwater. Construction of dams in rock regions requires stability analysis of the foundation and the supporting rocks at the banks of the reservoir area. Stability of the concrete foundation over the rocky strata and stability of the banks depend upon the shear strength of the concreterock and rock-rock interfaces, respectively. Therefore, evaluation of shear strength parameters (cohesion and friction angle) at rock-rock and concrete-rock interface is the most important primary step for stability analysis and design of dams. Determination of shear strength parameters involves the in-situ tests in drifts on the dam axis site and interpretation of test results. In view of the above, site-specific shear strength parameter interpretation is carried out for Amochu hydroelectric power project site, Bhutan. This project envisages construction of 175m high concrete gravity dam across river Amochu. The existing rock type on both left and right banks of the site is observed to be weathered Phyllites. From the analysis of 20 field tests in 2 drifts, it has been found that for rock-rock interface shear strength values are approximately 50% higher at the right bank as compared to the left bank. On the other hand, for concrete-rock interface, this variation is around 10% only. Therefore, seeing the large variation of estimated shear strength in rock-rock interface, it is proposed to use individual bank stability analysis whereas, marginal variation in concrete-rock interface suggests the use of the combined analysis of the data from both the banks for foundation stability analysis.

Jain, S. K., & Pathak, S. (2012). Intensity based casualty models: case study of bhuj and latur earthquake in india. In World Conference on Earthquake Engineering–2012. Lisbon, Portugal: Sociedade Portuguesa de Engenharia Sısmica.

Casualty data from Latur (1993) and Bhuj (2001) earthquakes in India are analyzed to study the relationship of death rates with shaking intensity. A strong correlation is noted between intensity and death rates (correlation coefficient ~0.77). The expected (median) death rates are 0.31%, 1.77%, and 19.45% for intensity VII, VIII and IX in case of Latur, and 0.0029%, 0.049%, 1.92% and 4.92% for intensity VII, VIII, IX and X in case of Bhuj. The significantly higher death rates in Latur are due to building typologies and the time of the event. Thus, there is a factor of ~100 for intensity VII and a factor of ~10 for intensity IX, indicating that the empirical casualty models should be area specific and not country specific. A two-parameter empirical model has been proposed.

Ramana, G. V., Pathak, S., & Dev, H. (2019). Shear strength parameters of granite rock mass: A case study. In V. Stalin & M. Muttharam (Eds.), Geotechnical Characterisation and Geoenvironmental Engineering: Lecture Notes in Civil Engineering (Indian Geotechnical Conference-2016, IIT Madras) (Vol. 16, pp. 273–280). Springer, Singapore.

In situ shear strength parameters of rock mass are important design parameters required for design of structures founded on or constructed in rock mass. Block shear test method is quite popular among practicing engineers for determination of cohesion and friction angle of rock-to-rock and concrete-to-rock interface. Generally, at the stage of preliminary design, a value of desired shear strength parameters can be taken from available literature. However, such values must be used with proper engineering judgement. In case of rock mass, structural features of geology plays a very crucial role in affecting its engineering behavior. Same rock type may have significantly different shear strength parameters depending upon site-specific geological characteristics. In this paper, the variation in rock-to-rock and concrete-to-rock shear strength parameters of rock mass consisting of primarily granites is studied among three different geological variants, namely (a) western part of Himalaya, (b) Garo-Khasi Hills of Meghalaya, and (c) Eastern Ghat Belt of Andhra Pradesh. The variation in shear strength, cohesion, and friction angle is studied in terms of strength ratio, cohesion ratio, and friction angle ratio. These values are also compared with values for granites available in the literature. Site parameters supported with quantitative analysis of in situ data indicate that highest shear strength is expected at Eastern Ghat Belt and least shear strength at Garo-Khasi Hills.

Ramana, G. V., Moghal, A. A. B., & Pathak, S. (2021). Reappraisal on the field tests for determination of rock mass characteristics for open terrain(s). In Patel, S. et al. (Ed.), Proceedings of the Indian Geotechnical Conference 2019, Lecture Notes in Civil Engineering (Vol. 137, pp. 711–721). Springer, Singapore.

For site investigations pertaining to hydropower project(s), often the suitable in-situ testing protocols are limited in open terrains due to constraints in carrying out them on rock masses. Such scenarios necessitate the utilization of available resources to the best possible extent, in carrying out sampling procedures required for evaluation of design parameters like shear strength (concrete over rock; rock over rock) and deformability characteristics of rock mass. In order to carry out these tests, it is mandatory to get enough upward reaction for the expected structural loads (which are usually of higher magnitude), for better engineering judgements. These loads will have to be compounded to the conservative side, by at least 1.5–2 times of the expected design loads. In order to meet this requirement, particularly in drift areas (small audits), the crown reaction due to cover is sufficient. However, in most of the open terrains, the reaction is provided by relying on Kent-ledge arrangement by providing sufficient loading arrangement such as sand bags, concrete blocks, etc., a time taking process involving considerable risk. The current manuscript deals with instances encountered under difficult open terrains in carrying out required tests, and suggests suitable site specific solutions with available resources within the working area. The authors believe that, the proposed solutions presented in this manuscript will benefit the practicing engineers and stake holders working in the geotechnical investigations pertaining to in-situ rock testing.

Pathak, S. (2023). A combination of innovative pedagogical theories to enhance the learning output—a case study with engineering students. In Engineering Pedagogy: A collection of articles in honor of prof. Amitabha Ghosh (pp. 49–61). Springer.

An all-around growth of a nation cannot be possible without a good quality education at all the learning levels (from nursery to higher education). Therefore, providing an effective education is a crucial responsibility for professional educators. A detailed literature review highlights that several advanced and innovative pedagogical methods are available. However, in higher educational institutes, most of the educators, who are researchers and experts in a specific field, usually rely on their in-built teaching aptitude due to the lack of a formal pedagogical training. Therefore, the case studies demonstrating the application of existing pedagogical theories in real-time classrooms can be quite useful for such educators. In view of this, a case study is being presented which focuses on improving the performance of a small undergraduate engineering class consisting of students with poor past track record in ‘Engineering Mechanics’ course. The present case study demonstrates that an appropriate combination of innovative pedagogical techniques such as (i) personal interview-based course-content design, (ii) grading scheme focused on the all-around assessment and effective learning, (iii) experimentation with lecture delivery and examination pattern, and (iv) reward policy for motivation can significantly enhance the learning outcomes of the class. Based on this case study, several key recommendations are made that can be conveniently adopted by educators who are not specialists in pedagogical research. These recommendations highlight the importance of (i) course content, (ii) examination pattern, (iii) lecture delivery, (iv) grading scheme, (v) motivational techniques, and (vi) overall learning goals.