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| Bootstrap estimation for geotechnical parameters of small samples and slope stability analysis |
| LUO Fei1，2，LUO Qiang1，2，JIANG Liangwei1，2，ZHANG Wensheng1，2，LI Ang1，2 |
(1. School of Civil Engineering，Southwest Jiaotong University，Chengdu，Sichuan 610031，China；
2. Key Laboratory of High-speed Railway Engineering，Ministry of Education，Chengdu，Sichuan 610031，China) |
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Abstract The confidence interval of geotechnical parameters calculated by the t-distribution method is too wide under the small sample condition which leads to the conservative engineering design. The simulation on the random sampling survey for small samples was therefore conducted based on the population of c，φ which reflect the inherent variability of soil. The interval and point estimation results were obtained using the Bootstrap method to reconstruct the datum. The differences of the parameter estimation from the t-distribution method and Bootstrap method were compared. The discrete characteristics of safety factors of slope stability were analyzed based on the parameter estimation space built by the sufficient number of repeated sampling. For the same confidence level，the Bootstrap method sufficiently takes advantage of the empirical distribution information of small samples and effectively narrow the mean confidence interval of c，φ，and their lower limit values with guarantee rate are closer to the true values compared to t-distribution method. The two methods yield the same results of mean and variance of point estimation，namely their reliability indexes of slope stability are equal，but the means of safety factors of slope stability calculated by the lower limit value with guarantee rate using the Bootstrap method are relatively large，the discreteness of safety factors decrease. The improvement becomes more obvious with the increase of the variance level of parameters. On the condition of the same reliability，the Bootstrap method can reasonably compensate the safety risk of slope caused by the statistical uncertainty from small samples.
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2017, Vol. 36 
