The empirical and numerical design approaches are considered very important in the viable and efficient design of support systems, stability analysis for tunnel, and underground excavations. In the present research work, the rock mass rating (RMR) and tunneling quality index (Q-system) were used as empirical methods for characterization of rock mass based on real-time geological and site geotechnical data and physical and strength properties of rock samples collected from the alignment of tunnel. The rock mass along the tunnel axis was classified into three geotechnical units (GU-1, GU-2, and GU-3). The support systems for each geotechnical unit were designed. The 2D elastoplastic finite-element method (FEM) was used for the analysis of rock mass behavior, in situ and redistribution stresses, plastic thickness around the tunnel, and performance of the design supports for the selection of optimum support system among RMR and Q supports for each geotechnical unit of tunnel. Based on results, Q support systems were found more effective for GU-1 and GU-2 as compared to RMR support systems and RMR support systems for GU-3 as compared to Q support systems.

An experimental work has been carried out to study the flexural behavior of cast in-situ hollow core reinforced concrete (HCRC) slabs constructed by using easy, cost effective and implementable techniques in field. The precast elements made of different easily available affordable material i.e. concrete, polyvinyl chloride (PVC) and plaster of paris having voided cross- sections of circular, rectangular and triangular shapes were incorporated in one direction during pouring of concrete with minimum flexural reinforcement to construct HCRC slabs. A total of 14 slab specimens including 02 specimens per specification were tested with third point loading for the assessment of flexural behavior as per ASTM standards C78/C78M. The flexural behavior of HCRC slabs with polyvinyl and plaster of paris elements having hollow cross-sections was comparable with the control solid slabs, however, HCRC slab with concrete pipes showed 7 to 8 percent reduction in flexural strength with 19 to 20 percent reduction in self-weight. All the tested specimens performed well in shear as no shear failure was observed. This study reveals that HCRC slabs with locally available material having hollow cross section elements can be used for the construction of cast in-situ monolithic construction of one-way slabs with ordinary construction techniques. Doi: 10.28991/cej-2020-03091597 Full Text: PDF

The geological strength index (GSI) is one of the most exceptional rock mass classification system which is used to evaluate very weak and highly jointed rock mass by different approaches and related to rock mass geomechanical properties including generalized Hoek & Brown constants, deformation modulus, strength properties, and Poisson’s ratio for an appropriate design of tunnels, caverns, and other engineering structures. The distinctiveness of this system over the rock mass rating (RMR), Q-system, and other empirical methods is as follows: it utilized field observations, blockiness of rock mass, and surface joint characteristics during the evaluation process of rock mass and efficiently espoused as an empirical tool for estimation of geomechanical properties of rock mass required for pre-post stability of engineering structures using numerical modeling. This study presents the review of the 19 years of research studies conducted by different researchers about the GSI in a systematic way, i.e., origination, modifications, applications, and limitations. Furthermore, this study will provide a better understanding to field professionals (geologists, mining and civil engineers) about the qualitative and quantitative estimation of the GSI and its application as an empirical estimating tool for an appropriate design of engineering structures in rock mass environments.

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Objectives: To evaluate the estimates of burden of cardiovascular diseases (CVD) in South Asian (SA) region from 1990 to 2019 using the Global Burden of Disease (GBD) study. Methodology: Data for this ecological study was extracted from the Global Health Data Exchange query tool for 30 years from 1990 to 2019. Dataset consisted of prevalence, deaths, and disability-adjusted life years (DALYs) due to CVD summarized as estimated number of cases and rate per 100 thousand individuals for Pakistan, India, Bangladesh, Nepal, and Bhutan and South Asian region. Results: An increasing trend has been noticed in overall prevalence rate and death rate of CVD in the SA region in the past 30-years from 1990 to 2019. A relative increase of 49.6% was noted in the prevalence rate of CVD per 100,000 population with 3304.2 and 4944.1 cases per 100,000 in the year 1990 and 2019, respectively. Similarly, a relative increase of 30.3% was noted in mortality rate due to CVD with 139.8 and 182.1 deaths per 100,000 in the year 1990 and 2019, respectively. Ischemic heart disease (IHD) remained the highest contributor with 56.51% (1857.9×1000 cases) share to the regional mortalities followed by stroke with 29.77% (978.9×1000 cases). Conclusion: SA region is experiencing and increasing trend in prevalence, deaths, and DALYs due to CVD. IHD and stroke remained the main contributors to the regional burden of CVD followed by stroke. Targeted preventive measures are required involving all the stakeholders from community to policymakers.

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Objectives: This study was designed to compare the in-hospital outcomes of primary PCI with export vs. primary PCI with the balloon in patients with total occlusion. Methodology: Consecutive patients with STEMI undergoing primary PCI with TA and pre-balloon dilatation were recruited in 1:1 ratio and post-procedure in-hospital mortality and complication rate (slow flow/no-reflow, contrast-induced nephropathy (CIN), and arrhythmias) were compared. Patients in the TA group were further stratified based on export time (time from onset of chest pain to the use of export) as ≤ 6 hours or > 6 hours. Results: A total of 200:199 patients were recruited in export and balloon group. Overall complications were significantly higher in balloon group, 39.7% (79/199) vs. 23.0% (46/200); p<0.001, which included slow flow/no-reflow (24.6% vs. 14.5%; p=0.005), CIN (10.1% vs. 4.5%; p=0.022), and arrhythmias (14.6% vs. 5.5%; p=0.006) with in-hospital mortality rate of 3.0% (6/200) vs. 6.0% (12/199); p=0.153. Upon stratifications, outcomes were more favorable  when export time was ≤ 6 hours as compared to > 6 hours with mortality rate of 0% vs. 6.3%; p=0.010 and complication rate of 19.2% vs. 27.1%; p=0.187. Conclusion: TA in patients with total occlusion was associated with lesser complications and relatively better mortality benefits. The benefits of TA were directly associated with export time. Therefore, timely use of export can be considered in patients with total occlusion.

Purpose. Empirical and numerical methods play a vital role in assessing rock mass behaviour quantitatively and qualitatively to design underground structures/caverns and support systems. This research aims to assess and evaluate the rock mass be-haviour for safe, stable, efficient, and economical design of support system for underground structures especially tunnels in diverse rock mass conditions. Methods. In this research, such empirical design methods as Rock Mass Rating (RMR), Q-system and GSI were used to characterize and classify the rock mass environment along the tunnel for the preliminary design of twin tunnels and support systems. The geomechanical parameters, Hoek-Brown failure criterion, and its variants for assessing rock mass behaviour were optimized using multiple regression of Stewart, generalized and globalized variant of nonlinear regression method. The rock mass was classified for the selected section A-A. The excavation method and support system for the said section were designed based on the results obtained from empirical modelling. 2D elasto-plastic finite element method (FEM) was used for numerical analysis of rock mass behaviour and performance of the designed supports in section A-A. Findings. The major rock type encountered in the diversion scheme comprises gabbronorite (GN) and Ultramafic Association (UMA). Based on the quantification of RMR, Q-system, and GSI, section A-A’s rock mass ranges from very poor to poor. From the numerical analysis for the said rock mass environment both RMR and Q system support recommendations are equally efficient to support the rock mass surrounding the tunnel. However, keeping in view the yield zone, especially in the crown, the rock bolt’s length should not be less than 5 meters. Based on the analysis of results, both the tunnels are at a safe distance from each other. Originality. In this research, the design input parameters for numerical modeling were optimized by using different techniques to eliminate the chances of error in evaluating rock mass behaviour and designing an optimum support system in the said rock mass environment. Practical implications. The assessment of rock mass behaviour and the design of optimum support systems in heterogenous conditions is quite challenging and requires thorough investigation through different design techniques. This research provides a refined meth-od to be used for the safe, stable, and economical design of tunnels.