Southern Districts of Telangana State of India are the worst drought-prone and distressed areas. There is a tremendous shortage of drinking water, as these are fluoride-affected areas. As a result, a large part of the population of these districts is being forced to migrate to other parts of the country. In view of the drought situation in the area, the Palamuru-Rangareddy lift irrigation scheme (PRLIS) was planned. PRLIS is intended to irrigate upland areas of Mahabubnagar, Rangareddy, and Nalgonda districts for a command area of 497,976 ha (12.30 lakh acres) and provide water for industrial use also. PRLIS is being constructed to lift water in five stages by pumping it from the foreshore of Srisailam reservoir on the Krishna River (FRL + 269.735 m) to K. P. Lakshmidevipalli reservoir (FRL + 670 m). Underground pump house caverns are being constructed at five places to lift 2.0 TMC of water daily for 60 days during flood season. Systematic examinations of each structure of such a large project throughout the construction phase will guarantee their long-term stability and safe operation under any unfavourable conditions of natural or artificial origin. In this paper for the foundation of the pump house of Stage-I, where 9 pumps of 145 MW capacity each will be installed, engineering geological and geotechnical investigations are discussed. The rock mass categorization of the pump pit foundations was done based on engineering geological mapping, laboratory test results, and fieldwork. The Rock Mass Rating (RMR) assessment for granitic rock masses, based on the rock joints and their nature, drill holes, and laboratory test data has been done. Allowable bearing pressure was estimated from rock mass classification, RMR, RQD, and rock core strength. Engineering geological and geotechnical data were used to recommend and establish acceptance standards for the foundation grade levels for the installation of pumps.

Detailed engineering geological investigations were carried out for a railway tunnel which was constructed more than two decades ago. 3D engineering geological mapping was carried out using Brunton Compass and Total Station Surveying instruments in 1:100 scale. Coarse-grained pink and grey granite, hornblende-biotite gneiss and dolerite dyke of Archaean age and Lower Proterozoic age were mapped. Rock mass was intersected by sub-horizontal, inclined, and vertical joint sets, which were continuous and persistent, smooth, and planar with thick filling of decomposed and crushed sheared material or with thin coating of clay material. Based on the Q-system, rock mass was classified into different classes. On the basis of large-scale engineering geological mapping and Norwegian Method of Tunnelling, a support system was recommended which includes rock bolt, fibre reinforced shotcrete, grouting and reinforced ribs of sprayed concrete and the same is implemented by the agency. As per the best knowledge of the authors, reinforced ribs of sprayed concrete are first time used for transportation tunnels in India and it will be more effective if it will be compared with ISMB or Lattice Girder.

Detailed engineering geological and geotechnical investigations were carried out of the delivery mains for assessment of rock mass qualities and to provide a sound support system. Seven numbers of delivery mains are constructed which are an important component of the pump house complex for lifting water from the pump house to the delivery cistern. Regionally the rock types belong to Karimnagar Granulite Terrain (KGT) and Peninsular Gneissic Complex (PGC) of Archean age. The main rock types of delivery mains are medium to coarse-grained grey granite and charnockite traversed by dykes/basics enclaves. The rock mass was classified on the basis of rock mass rating (RMR) and tunnelling quality index (Q) classifications. The calculated classes of rock masses range between very poor to good. Geomechanical properties of the rock samples were tested as per IS codes. Delivery mains were constructed as per the Norwegian method of tunnelling (NMT) and support design as per the Q-system chart. Rock support in the form of rock bolts, steel fibre reinforced shotcrete and grouting arrangement were applied. The main challenge for the construction of seven delivery mains was the less rock ledges in between these delivery mains and presence of nearby live reservoir. So, before excavation, data was collected from adits and pump house heading portion to classify the rock masses of delivery mains. In this paper engineering geological investigations, challenges and design of rock support system is described in detail for seven delivery mains.

Safe and economical subsurface excavation requires a holistic assessment of the ground. Possibilities of stress-induced and structural failures need thorough consideration before excavation. Over-supporting an excavation is uneconomical while under-supporting can lead to disastrous results. Thus, in this research, an attempt has been made to devise the most efficient and reliable support system. An under-construction underground surge pool cavern to store and lift water at the Indian state of Telangana was taken up as the research site. The methodology involved in-depth geological and geotechnical investigations to identify possible adverse features. Rock mass rating and Q-index, were implemented for rockmass characterization. The surge pool was constructed using the Norwegian Method of Tunnelling (NMT) and validated with BIS codes. The stability analysis and support design were carried out with the help of distinct element simulation and wedge analysis for the surge pool heading portion. A right crown portion was found to be most susceptible to failure, which was also confirmed by the both the analysis. A thorough examination led to the most robust and economical support design for long-term stability.

Tunnel Boring Machine projects face several difficulties: reliability, availability, and optimum productivity. Predicting machine performance is one of the most important issues. Improper forecasting may necessitate rescheduling of the entire project, resulting in a significant cost overrun. The Rock Mass Rating (RMR) system, which is commonly used for the development of empirical equations for predicting TBM performance, has a limited scope of success due to the weights assigned to the input parameters. This issue could be overcome by adjusting weighting assigned to input parameters of RMR. In this research, multivariate linear and non-linear regression analysis and an Artificial Neural Network (ANN) model are built using the adjusted weights of the RMR input parameters for the evaluation of penetration rate for hard rock open gripper TBM for 5.834 km of the Maroshi-Vakola tunnel of the Ruparel-Maroshi tunnel project. The developed ANN9 model showed good agreement in predicting penetration rates with a highest coefficient of determination (R2) in training as well as in testing, with a lowest RMSE in training as well as in testing.

This research focuses on evaluating the rock masses geotechnical properties and recommending the optimal support design for an adit tunnel being constructed in the North Western Himalaya, India. Predicting rock mass behaviour with precision is dependent on accurate characterisation of in-situ rock mass properties. Tunnel performance in discontinuous rock masses is determined by geometric properties of discontinuities, resistance properties of the intact rock, and the influence of water. Difficulties emerge because the factors that describe these features are distributed rather than distinct. During the last 50 years, there has been significant progress in the stochastic description of discontinuous rock masses and the statistical distribution of their geometric properties. The tunnelling quality index (Q) and rock mass rating classifications were used to characterize the rock mass and based on rock mass categories; methodology of excavation was finalised. New Austrian Tunnelling method was utilised for the recommendation of tunnel support and primary support measures executed included forepoling, shotcrete, rock bolts, lattice girder, and steel ribs. The 2D finite element method was used to estimate the effectiveness of support design, plastic zone size, and deformations. The input geotechnical parameters which were required for modelling were derived/estimated. On the crown and walls, maximum displacement observed was 13.0 mm and 18.0 mm respectively. Using the MN curve, the capacity of a reinforced shotcrete section to resist bending and cracking is determined. Modelling indicated that support recommended was sufficient for adit tunnel stability point of view and deformation was within the permissible limit.

The documentation of excavation method and support design based on rock mass classification systems i.e. rock mass rating (RMR), Q-system and New Austrian tunneling method (NATM) for adit-7 tunnel being constructed in Garhwal Himalaya, India is discussed in this paper. The New Austrian tunneling method classes of rock units have been developed by using correlations with the RMR and Q systems, according to the ONORM B 2203. NATM principles were used because the geological conditions were continually changing. The study indicated that the RMR-based rock mass estimation was overstated, but the qualitative assessment was right. The NATM technique is more adaptable for Garhwal Himalayan rocks having various uncertainties in rock mass evaluation. The current adit investigations indicate that there are numerous unanswered concerns, concerning rock mass quality evaluation, tunnel behavior during construction and usability. Results of the analysis are considered to be useful for the design of the new tunnels constructed in the similar type of the terrain.

For better rock mass characterization, 3D engineering geological mapping and in-situ testing was carried for the heading portion of surge pool of Palamuru Ranga Reddy lift irrigation scheme lift-II. The direction of the longest axis of the surge pool cavern was finalized based on the in-situ hydrofracturing testing inside the borehole and aligning the appurtenant structures of pump house and surge pool cavern on the ground. Rock types mapped were grey and pink granites belongs to the Peninsular Gneissic Complex of Archaean age. The assessment of Tunnel Quality Index ‘Q’ for the exposed granitic rock mass was done based on the information available of the rock joints and their nature, 3D geological mapping and in-situ stress measurement. The rock mass quality (Q) is related with the ultimate support pressure requirement. Excavation Support Ratio (ESR) as given in the ESR updated classification standard of NMT Q-system is applied to 1.0 for this cavern. On the basis of NMT Q-system chart and site geological characteristics, support system is recommended and its efficacy is assessed.

INTRODUCTION Analytical approaches such as kinematics, limit equilibrium or finite element methods are used mainly in analysing the rock slope stability. The mathematical formulation of the various methods depends upon the four general modes of failure namely planar slip surfaces, three-dimensional wedge-shaped slip surfaces, toppling and circular slip surfaces. Since the majority of sliding stability problems are indeterminate, a number of assumptions must be made about the location, orientation and possible magnitude of the forces involved in the analysis. The analytical analysis of three-dimensional problems can be substantially simplified with the use of stereographic projection. Once the problem geometry has been defined, an analytical method can be selected for assessing the sliding stability of the slope. In addition to the analytical methods, there are number of physical modelling techniques exists like Base Friction Modelling, Centrifuge Modelling and Scaled Models used for problems where analytical techniques may not be valid or may be too complex (Goodman, 1976). For rock slope stability assessment, engineering rock mass classifications are also developed but less frequently used. The main advantage of engineering rock mass classifications is that they are a simple and effective way of representing rock mass quality and of encapsulating precedent practice (Harrison and Hudson, 2000). Some of the important engineering rock mass classifications for slopes are Rock Mass Rating (RMR, Bieniawski, 1979, 1989), Rock Mass Strength (RMS, Selby, 1980), Slope Mass Rating (SMR, Romana, 1985, 1995), Slope Rock Mass Rating (SRMR, Robertson, 1988), Chinese Slope Mass Rating (CSMR, Chen, 1995), Natural Slope Methodology (NSM, Shuk, 1994), Slope Stability Probability Classification (SSPC, Hack, 1998), Modified Slope Stability Probability Classification (SSPC modified, Lindsay et al., 2001), Continuous Rock Mass Rating (Sen and Sadagah, 2003), Continuous Slope Mass Rating (Tomas et al., 2007), Fuzzy Slope Mass Rating (FSMR, Daftaribesheli et al. 2011), Graphical Slope Mass Rating (GSMR; Tomas et al., 2012), Modified Slope Mass Rating (M-SMR, Rahim et al. 2009, 2012), Global Slope Performance Index (GSPI, Sullivan, 2013), Rock Hazards Rating System (RHRS, Budetta, 2004) and Q-slope (Barton & Bar, 2015 and Bar & Barton, 2017). Some of the above engineering classifications are modifications from the original ones. Typical examples of slopes cut in rock include: foundation excavation; construction of roads; and development of dam abutments, spillways, and tunnel portals. The primary objective of any rock excavation is to minimize the volume of rock excavated while providing an economical and safe excavation suitable for its intended function (EM 1110-1-2908). The objectives of the economy and safety, as a rule, involve the maximization of the angle of inclination of the slope while assuring stability, which can be achieved using engineering rock mass classification. In both civil engineering and mining projects, it is practically impossible to assess the stability of rock cuttings and benches in real-time, using analytical approaches such as kinematics, limit equilibrium or finite element methods (Barton and Bar, 2015). In these case excavations is generally very fast and stability assessment can be done by engineering rock mass classification.

Underground pump house cavern for the lifting of 2.0 TMC water per day is being constructed in the Telangana State of India. Concurrently with the excavation of the pump house, 3D engineering geological mapping was carried out of the heading portion for rock mass classification and recommendation of support. The direction of the longest axis of the pump house was finalized based on the in situ hydrofrac testing inside the borehole. Classification of rock mass was done following the Tunnel Quality Index ‘Q’ method. Ground condition was non-squeezing; accordingly, Q-values were used for the estimation of roof support and walls support pressure. Based on NMT technology and site geological conditions, rock support arrangements were recommended for structural stability of crown and walls. Using the integrated approach, the capacity of the support system is determined to appraise the efficacy of the planned support system.

Engineering geological and geotechnical assessment of the dam foundation are essential for the design of the dam to ensure safety. At the southeastern part of Karnataka, Yaragol gravity dam is being constructed, which is designed based on site geomorphological and geological conditions and economic reasons. This paper discusses the results of the engineering geological and geotechnical investigations that have been carried out at the foundation levels of the dam. The dam foundation is composed of foliated gneiss and granite gneiss belonging to Archean to Paleoproterozoic age with intrusive dykes. This study is based on field and laboratory investigations, surface discontinuity mapping, drilled borehole data and in-situ shear testing. In-situ shear parameters of rock-rock interfaces and concrete-rock interfaces were conducted for the evaluation of dam stability against sliding. The classification and rock mass quality of the dam site is assigned using the rock mass rating (RMR) for all the 19 blocks and allowable bearing pressure (qallow) is assessed based on rock types and RMR. At all the blocks foundation, geological defects were mapped and analyzed and treated with suitable engineering measures. Based on structural features mapped, curtain grouting and consolidation grouting is recommended.

Underground surge pool cavern for the storage and lifting of water is being constructed in the part of Telangana State of India. For better rock mass characterization and support design, 3D engineering geological mapping was carried for the heading portion of the surge pool. 3D geologic mapping of heading portion is very important for large underground cavern to know about the cavern behavior during benching down. The direction of the longest axis of the cavern was finalized based on the in-situ hydrofracturing testing inside the deep borehole. The assessment of tunnel quality index ‘Q’ for the exposed granitic rock mass was done based on the information available of the rock joints and their nature, 3D geological mapping and in-situ stress measurement. Roof support and wall support pressure was estimatedbased on Q-values, and in this case applicable for the non-squeezing ground condition. For structural stability of crown and walls, rock support arrangement was recommended based on NMT technology and geological conditions of site, which includes steel fibre reinforced shotcrete, grouting, rock bolt and drainage hole provisions. The capacity of support system is determined to evaluate the efficacy of the proposed support system.

During last five decades many attempts have been made to develop a means of assessing the excavatability of rock. These classifications have been used to select appropriate excavation systems and equipment used in civil and mining works. Empirical rating and seismic velocity systems are proposed for the rippability of a rock mass. In this paper rock mass classification systems i.e. rock mass rating system and tunnel quality index and revised excavatability graph are used for assessing the excavatability of rock. The aim of this study was to examine how the intact rock and rock mass properties influence the excavatability of rock surface excavation in granite and gneiss terrain. These methods allow the excavatability of rock to be assessed rapidly. After detailed study it is concluded that rock mass rating system gave a better assessment of rock mass quality than the tunnel quality index and revised excavatability model.

For the deep underground pump house complex engineering geological and geotechnical investigations were carried out. The area was investigated through detailed engineering geological mapping, exploratory drilling, in-situ stress measurements and laboratory testing. Surface mapping was done on 1:500 scales with 0.5 m contour interval and drill holes logging was done on 1:100 scale. The rock mass properties, i.e. joint sets, weathering grade, RQD etc. of the rock masses to be encountered during the excavation of cavities have been analyzed in detail. Core samples from the exploratory drill holes drilled at the surge pool and pump house area were tested for physico-mechanical properties of rocks in the laboratory. To evaluate the stress regime at the proposed underground pump house complex area, stress measurements were carried out by hydrofracturing method inside the borehole. The mapping details indicated that cavities will be excavated through fresh, coarse to very coarse grained, hard and jointed granites. The average depth recorded of fresh rock from the surface was 15.7 m. The uniaxial compressive strength of the rock mass range from 221 to 246 MPa. The orientation of the long axis of the cavities recommended is N150°. Classification of rock mass using Tunnelling Quality Index Q is attempted and the values are range from 3.58 to 16.40.

Geotechnical assessment of the foundation including engineering geological investigations are essential for important civil structures to provide permanent data set for geological interpretations and for recommendations of suitable engineering measures for the improvement of the foundation. Yaragol Gravity Dam for drinking water is being constructed across Markandaya river in Karnataka State of India. Engineering geological mapping on 1:200 scale was carried out for Housing Chamber of Yaragol Gravity Dam to evaluate the design basis foundation parameters. 2 m x 2 m grids were prepared for mapping of the floor. Based on the field observations and evidences, it was found that the floor area consists of foliated gneiss and granite. No evidence of faulting or shearing was observed on the surface of the floor area. Geotechnical assessment of the foundations was done on the basis of detailed engineering geological mapping and laboratory test results. Classification of rock mass using Rock Mass Rating (RMR) of Bieniawski (1989) has been attempted and based on investigations recommendations for the treatment of foundation were given. Rock type and Rock Mass Rating (RMR) methods were used for assessing the safe bearing pressure of the foundation. Consolidation grouting up to 6 m depth in the foundation using primary at 6 m spacing and secondary holes at 3 m spacing was recommended. After detailed investigations it was found that, the foundation is suitable to locate a housing chamber.

Engineering geological foundation investigations are essential for important civil structures to provide permanent data set for geological interpretations.At Rawatbhata, India, two units of 700 MW each Pressurized Heavy Water Reactor (PHWR) type Nuclear Reactors are being constructed adjacent to existing Rajasthan Atomic Power Project (RAPP) units 1 to 6. Engineering geological mapping on 1:100 scale was carried out for Nuclear Building-8 structures to evaluate the design basis foundation parameters. 1 m x 1 m grids were prepared for mapping of the floors and walls.Based on the field observations and evidences, it was found that the floor area consists of fine to medium grained, compact quartzitic sandstones.The floor region was seen to contain certain iron stained and fractured zone.No evidence of faulting was observed on the surface of the floor areas.However, there were some isolated patches of soft, weathered/altered rock and small fractures in the rocks.The intact rock properties at the foundation levels were evaluated considering the necessity in the overall context of the design requirements of the foundations.Geotechnical assessment of the foundations of RB-8, RAB-8 and ECCS north and south pits was done on the basis of detailed engineering geological mapping, geological drill holes logging data, rock mass permeability values, geophysical profiling and laboratory test results.Based on investigations recommendations for the treatment of foundations were given.Consolidation grouting up to 9 m depth in the foundation using primary at 6 m spacing and secondary holes at 3 m spacing was recommended.After detailed investigations it was found that, the foundation is suitable to locate a nuclear power plant.

For better rock mass classification and support design of supporting system, geotechnical investigations were carried out for the proposed 196.80 m long, 50.30 m high and 25.24 m wide underground pump house cavern of a lift irrigation scheme. Geotechnical site investigations, rock support design, excavation and related works and modification of supports design according to the observational construction method are the principal activities for the construction of underground rock cavern. The investigation includes engineering geological mapping, geological logging of drill holes, in situ permeability test and laboratory testing on core samples. Detailed geotechnical investigations carried out supporting the feasibility of underground excavations of cavern within the hillock. Support system recommended is the rock bolt and steel fibre reinforced shotcrete based on empirical approaches and their capacity is determined. Capacity of support system was conducted to evaluate the efficacy of the proposed support system.

In this paper a new methodology for evaluation and classification of support system that can be applied to rock tunneling is discussed. It is of great importance to consider long-term stability of rock mass around the openings of underground structure, during design, construction and operation. Varying geological conditions can lead to complications with respect to any underground excavations. The support system may be designed based on empirical, analytical and numerical methods. The support should be installed immediately after the excavation, delayed causes deformation. In this context, many temporary support techniques are chosen to perform as pre-support that can be installed during the first face of excavation around of underground openings. Temporary support used before the excavation for poor rock mass quality to increase the stand-up time by making generally an arch. These supports can also be installed during the excavation and in this paper Arch Method is discussed. Three types of techniques are used in arch method viz. forepoles, grouted arch & spiles. This method is highly recommended and proven system that can be installed within tunnel excavation.