Assessment and calibration of two models for estimation of soil nail loads and system reliability analysis of soil nails
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RESEARCH PAPER
Assessment and calibration of two models for estimation of soil nail loads and system reliability analysis of soil nails against internal failures Yongqiang Hu1 • Peiyuan Lin2,3,4,5
•
Chengchao Guo2,3,4,5 • Guoxiong Mei2,3,4,5
Received: 25 November 2019 / Accepted: 22 May 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This study first presents accuracy assessments of two default models proposed in two popular soil nail wall design specifications and their calibrated versions for estimation of maximum soil nail loads under operational conditions. The assessments are based on a general nail load database reported in the literature. Evaluation results showed that predictions using the default and calibrated models are unsatisfactory as the dispersions are high to extremely high. Simple calibration terms are introduced to the calibrated models for performance enhancement. The recalibrated models are shown to be accurate on average, and the prediction dispersions are significantly reduced. The model biases for the above six models are demonstrated to be lognormal random variables. Individual reliability-based designs for the nail pullout and nail-in-tension limit states using the six models are carried out. System reliability of nails against internal failures is also explored. The correlation between the two limit states is investigated, and its influences on system reliability evaluation are discussed. The practical value of model calibration is demonstrated as using the recalibrated models for nail designs leads to the most cost-effective design outcomes. This study represents a solid step toward development of reliability-based design framework for soil nail walls. Keywords Internal limit states Maximum nail load Model calibration Model uncertainty Soil nail wall System reliability
& Chengchao Guo [email protected] Yongqiang Hu [email protected] Peiyuan Lin [email protected] Guoxiong Mei [email protected] 1
School of Civil Engineering, Guangzhou University, Guangzhou 510006, Guangdong, China
2
School of Civil Engineering, Sun Yat-Sen University, Guangzhou 510275, Guangdong, China
3
Guangdong Provincial Key Laboratory of Oceanic Civil Engineering, Guangzhou 510275, Guangdong, China
4
Guangdong Provincial Research Center for Underground Space Exploitation Technology, Guangzhou 510275, Guangdong, China
5
Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangzhou 510275, Guangdong, China
1 Introduction Estimation of the maximum tensile load that a soil nail would sustain during its service life is an important step for design of soil nail walls against internal failures, including nail pullout and nail-in-tension limit states. In China, soil nail walls are usually designed according to either one of the two national specifications: Technical Specification for Retaining and Protection of Building Foundation Excavations by China Academy of Building Research (CABR) [7] or Sp
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