Stability Analysis of Rock Slope
Geotechnical engineering plays an important role in civil engineering as it enables the engineer to understand the behaviour of the soil and its applications in the construction and development of infrastructure. Stability analysis of slopes is a common application of geotechnical engineering that helps determine the stability of slopes in natural and man-made landscapes. In this report, the stability analysis of a rock slope is discussed.
Firstly, the soil parameters that are usually important in slope stability analysis are identified. These parameters include soil particles size distribution, particle shape, grain size, shear strength (cohesion and friction angle), pore water pressure and unit weight, depending on the soil condition. In this case, due to the fact that the slope is composed of rock, these parameters are assumed to vary little and thus can be omitted in the analysis.
For rock mass, the intact rock properties such as uniaxial compressive strength (UCS) and the jointing characteristics (joint orientation, joint surface roughness, etc) are important. In this report, the UCS and joint roughness (jr) of the rock must be determined. This can be achieved by conducting a test such as point load test (PLT).
The PLT consists of applying an axial force to a small diameter rock core which is embedded in the intact rock mass. The test measures the amount of force required to crush the core and therefore the UCS for the rock can be determined. The joint roughness is also determined in this test through the measurement of the force on the core at different depths in the rock.
The next step is to determine the strength of the jointed rock mass. The strength of the jointed rock mass, or the so-called ‘Gudmundsson parameter’, is typically determined by using the correlation between rock UCS and joint roughness (jr). In this case, due to the fact that the UCS and jr have been determined previously, the Gudmundsson parameter can be calculated directly.
The next step is to determine the load condition on the rock slope and the associated safety factor against failure. This can be achieved through the use of the strength reduction technique. The technique makes use of the strength parameters of the rock to determine the factor of safety against failure. The factor of safety is then compared to the target factor of safety, which is typically set according to the engineering standards or regulations that govern the construction of the slope.
Finally, the analysis of the rock slope is concluded. It was found that the Gudmundsson parameter for the rock slope was adequate to ensure the stability of the slope. Also, the factor of safety was found to be within the acceptable range as set by the engineering standards. This indicates that the rock slope is safe and can be constructed as planned.
In conclusion, this report discussed the stability analysis of a rock slope. The analysis was conducted through the use of PLT to determine the intact rock properties, the strength reduction technique to determine the load condition and the associated factor of safety, and the Gudmundsson parameter to assess the stability of the rock mass. It was found that the rock slope can be constructed as planned as the factor of safety was within the acceptable range.
