Due to extensive road widening project in the Himalayas, the roads experience huge instability problems especially during monsoon season. For the present study, 50 rock slope sites were considered over a stretch of 35 km on a national highway. The various attributes of discontinuities governing the slope failure were observed and the joint spacing in the stretch of the national highway is studied in detail. Detailed scanline survey was carried out and a database comprising more than about 6000 datapoints was generated. It is observed that the joints are spaced between 1 cm to 60 cm for the stretch of road. Statistical analysis of the joint spacing shows that most of the joint sets follow Exponential distribution, Weibull distribution, and lognormal distribution. Slope stability analysis was performed using the joint spacing data for all the slopes. It was observed that 50% of the slopes were susceptible to failure.
Engineering designs for rock slopes sometimes include discontinuities as a source of uncertainty and variable. The strength and geometric characteristics of the discontinuities are liable to change inside a rock slope, which is frequently observed in difficult and challenging terrains such as hilly regions (Basahel & Mitri, 2019). Spacing of discontinuities is one of the indispensable parameters of rock slopes which is used to determine the block size, the hydrogeological permeability, deformability, and strength of the rock masses (Wong et al., 2018).
Joint spacing in rocks have been studied by a number of researchers, and have reported to follow the Lognormal Distribution (Becker & Gross, 1996; Pascal et al., 1997; Wong et al., 2018), the Gamma Distributions (Castaing et al., 1996; Gross, 1993), the Negative Exponential Distribution (Hudson & Priest, 1983; Priest & Hudson, 1976, 1981), the Weibull Distribution (Wong et al., 2018) and the Normal Distribution (Ji & Saruwatari, 1998).
In the present study, 50 different rock slope sites were considered over a stretch of 35 km on a national highway. Detailed scanline survey was done to assess the spacing of the joints and a database which comprises of more than 6000 joints were generated.
