Study on Triaxial Creep Test and Constitutive Model of Compacted Red Clay

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RESEARCH PAPER

Study on Triaxial Creep Test and Constitutive Model of Compacted Red Clay Zhilin Long1 • Yuzhu Cheng1 • Guoyue Yang1



Dong Yang1 • Yunlong Xu1,2

Received: 26 March 2020 / Revised: 6 September 2020 / Accepted: 24 September 2020 Ó Iran University of Science and Technology 2020

Abstract To study the stability of fill roadbeds for railway-private sidings at the Anning refinery in southwest China, a series of triaxial creep tests of compacted red clay was carried out using an SLB-1 stress–strain controlled triaxial shear permeability tester. In this paper, under different confining pressures, stress levels and drainage conditions, the creep characteristics of the red clay compaction were studied. The results showed that the creep characteristics of compacted red clay were significantly affected by confining pressure, stress level and drainage conditions, and the compacted red clay showed the characteristic of creep attenuation. The stress–strain isochronal curves indicated obvious nonlinear characteristics, which formed a cluster of curves with the uniformization procedure, whereas under drainage conditions, the stress–strain isochronal curves presented a certain linear relationship. Moreover, according to the stress–strain curves, the long-term strength of the compacted red clay was 0.54–0.72 times the instantaneous strength. Furthermore, taking the triaxial creep test of the compacted red clay under a confining pressure of 300 kPa as an example, the data were analyzed, and a new empirical creep model was established. Compared with the Burgers model and the Singh–Mitchell model, the calculated curve of the new empirical creep model is in good agreement with the experimental curve. The new model, which has fewer parameters that are easier to get, has the advantage of a higher accuracy. The new empirical model can better reflect and predict the creep characteristics of compacted red clay in the filling roadbeds of the special railway line at the Anning factory refinery in southwest China. Keywords Compacted red clay  Triaxial creep tests  Stress–strain curves  Creep characteristics  Creep model

1 Introduction

& Guoyue Yang [email protected] Zhilin Long [email protected] Yuzhu Cheng [email protected] Dong Yang [email protected] Yunlong Xu [email protected] 1

College of Civil Engineering and Mechanics, Xiangtan University, Xiangtan 411105, China

2

Jianke Architectural Design Institute of Guangdong Province Co., Ltd, Guangzhou 510000, China

Red clay, which is distributed widely in southwest China, is a special kind of soil with a high liquid limit, a high plastic limit, a high moisture content and a high void ratio that is widely used as a building material in red clay distribution areas due to its sufficient stability, high strength and low compressibility [1–3]. However, the creep problem of red clay has become a common problem in the construction process of engineering projects in southwest China due to its engineering characteristics such a