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Geomechanics and Engineering
  Volume 27, Number 6, December25 2021 , pages 551-560
DOI: https://doi.org/10.12989/gae.2021.27.6.551
 


Stability evaluation model for loess deposits based on PCA-PNN
Guangkun Li, Maoxin Su, Yiguo Xue, Qian Song, Daohong Qiu, Kang Fu and Peng Wang

 
Abstract
    Due to the low strength and high compressibility characteristics, the loess deposits tunnels are prone to large deformations and collapse. An accurate stability evaluation for loess deposits is of considerable significance in deformation control and safety work during tunnel construction. 37 groups of representative data based on real loess deposits cases were adopted to establish the stability evaluation model for the tunnel project in Yan'an, China. Physical and mechanical indices, including water content, cohesion, internal friction angle, elastic modulus, and poisson ratio are selected as index system on the stability level of loess. The data set is randomly divided into 80% as the training set and 20% as the test set. Firstly, principal component analysis (PCA) is used to convert the five index system to three linearly independent principal components X1, X2 and X3. Then, the principal components were used as input vectors for probabilistic neural network (PNN) to map the nonlinear relationship between the index system and stability level of loess. Furthermore, Leave-One-Out cross validation was applied for the training set to find the suitable smoothing factor. At last, the established model with the target smoothing factor 0.04 was applied for the test set, and a 100% prediction accuracy rate was obtained. This intelligent classification method for loess deposits can be easily conducted, which has wide potential applications in evaluating loess deposits.
 
Key Words
    intelligent classification; loess deposits; principal component analysis; probabilistic neural network; stability evaluation
 
Address
Guangkun Li, Maoxin Su, Yiguo Xue, Qian Song, Daohong Qiu, Kang Fu and Peng Wang: Geotechnical and Structural Engineering Research Center, Shandong University, Ji'nan 250061, Shandong, China
 

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