The rock units of the NW Himalayan region are fragile, heavily fractured and highly deformed due to active tectonics and complex geological setup. Fast urbanization, road constructions along hill slopes and other infrastructural development activities also increased the slopes instability problems. The present study emphasizes the application of rock mass classification to estimate the rock mass properties along the Yadgar section Muzaffarabad, NW Himalayas, Pakistan. For this purpose, Rock Mass Rating (RMR) and Geological Strength Index (GSI) were used to characterize and classify the rock masses. In the present study, twenty-five sites have been investigated to evaluate rock properties along the Muzaffarabad-Neelum road, Sub-Himalayas, Pakistan. Result of the study shows that the Abbottabad Formation of Cambrian age is vulnerable in the Yadgar section with extremely poor RQD (Rock Quality Designation), lowest UCS (Unconfined Compression Strength) values and closely spaced discontinuities. and RMR values of the Abbottabad Formation ranges from 40-54 and classified as Poor to Fair having low GSI (20±3-35±3), blocky, disintegrated structure. The Paleocene Hangu Formation has lowest GSI (28±3-29±3; Blocky, Disturbed/ Seamy in nature) having RMR (40-45) and Eocene Kuldana Formation has GSI (30±3-45±3; Blocky) having RMR (34-67), are categorized as heavily broken, disintegrated and poorly interlocked rock masses. RMR values of rock units of the Paleocene Lockhart Formation (52-60), the Miocene Murree Formation (38-63), and the Eocene Margala Hill Limestone (38-61) are relatively higher values having GSI values ranges from (35±3-45±3; 35±3-50±3; 30±3-40±3) res)ectively. RMR and GSI values in Yadgar section, ranges between 34-67 and 20±3-50±3 respectively. Analysis shows positive correlation between GSI and RMR values. This approach to evaluate the rock mass classification through RMR and GSI will give the better estimation of rock mass properties along Muzaffarabad-Neelum road to identify the vulnerable slopes and design effective geotechnical measures.
The technique of assessing the failure of rigid overlying strata is applicable to deep mining with thick coal seams (a thickness of more than 1 m in the Ostrava-Karvina Coalfield), and in one case to longwall mining with controlled caving. The assessment of failure of rigid overlying strata makes it possible to distinguish whether the rigid overlying strata of rocks has been deformed or whether a strutting arch has been formed over the goaf below which is an area that is free from stress. Good knowledge of the mining, technical and geological conditions of a given site is a prerequisite for successful evaluation. There are advantages to utilising surface measurements for interpreting the effects of changes in rock mass, especially in areas of high overlying strata. The practical importance of failure assessment of overlying strata consists in determining the size of the mined-out area where the deformation of the rigid overlying strata occurred, which is dependent on the character of the rock mass. This paper is set in the context of the expected width of the goaf during deformation of rigid overlying strata within parameters that describe the mining and geological conditions of the locality. Changes in the area of the goaf, based the results of tensometric measurements, will also be placed in context., Eva Jiránková, Lubomír Staš, Vlastimil Kajzar and Hana Doležalová., and Obsahuje bibliografii