Stability analysis of soil-rock slope (SRS) with an improved stochastic method and physical models

With the development of traffic, many highways were built on the top of soil–rock slope (SRS). However, the effect of highway load on the SRS stability has never been studied comprehensively. Therefore, based on the statistical analysis, the stability of SRS considering additional loads of highway was studied. For generating a more realistic slope model, the identification algorithm of rock characteristic parameters was described considering rock ellipticity and long axis inclination angle; the corresponding rock contour establishing method and SRS establishing process were detailed, which could well consider rock content, ellipticity and long axis inclination angle. Applying the stochastic program, 522 stochastic numerical models and corresponding 12 physical models were created to study the influence of rock contents and long axis inclination angles on the SRS stability. The obtained results showed that the additional loads and dispersion degrees of stochastic analyzing results increased with the increase of rock contents, which were related to plastic developing modes (detour, through, scatter and contain modes) of SRS. By adjusting long axis inclination angles of rocks, it was observed that the minimum or maximum additional load was, respectively, obtained when this angle was parallel with or vertical to plastic belt. The effect of long axis inclination angles to the additional load (30.5%, 38.3% and 60.8% for 20%, 40% and 60% rock content) were concluded, which proved the necessity to consider long axis inclination angles of rocks in estimating SRS stability, especially in high rock content. According to numerical analysis results and the failure characteristic of physical models, three typical development modes of plastic belt of SRS were concluded when the load was on the top of slope, including deep, shallow and partial failure of SRS. In addition, it can also be found that the sliding body shows collapse (whole) modes when long axis inclination angles for rocks are vertical (parallel) to the plastic belt.