Accumulated Deformation Behavior and Computational Model of Water-Rich Mudstone Under Cyclic Loading

Abstract

With the rapid development of Chinese railway systems, a large number of railway tracks have been built on or across soft soils and soft rocks, resulting in problems such as accumulated deformation and settlements of the tracks (Zhang et al. 2009) and severe mud pumping in railway tunnels which are built through soft soils (Zhu and Li 2001). Such problems are a big challenge to the safety and efficiency of train operation. Investigations on the characteristics of long-term deformation of geotechnical materials under cyclic train loading are of great interest in engineering practice. Sangrey and Henkel (1969) conducted triaxial cycling tests for saturated soft clay and demonstrated the existence of a critical stress state for soils. Yasuhara and Yamanouchi (1983) performed a triaxial drained test on soft soils under cyclic loading. Muhanna (1994) reported that the permanent deformation of soils was proportional to the cyclic loading number and stress level. Jafari et al. (2004) conducted a systematic study on the fatigue behavior of artificial rock joints that were subjected to cyclic shearing. Bagde and Petros (2005, 2009) analyzed the fatigue behavior of intact sandstones under dry and saturated conditions with dynamic uniaxial cyclic loading. Erarslan and Williams (2012) studied the stress–strain characteristics of Brisbane tuff disc specimens under a diametral compressive sinusoidal cyclic loading with an increasing magnitude. Chinese researchers have also conducted extensive research in this area. Several cyclic triaxial tests have been conducted with different soil types. Systematic studies have been conducted to evaluate the characteristics of cyclic deformation and identify their influencing factors (Cai and Cao 1996; Tang et al. 2003; Gong et al. 2009). Several empirical models based on the results of cyclic loading tests have been developed to describe the cyclic cumulative deformation behaviors of different geotechnical materials. Monismith et al. (1975) proposed an exponential model for the cumulative plastic deformation of clay under cyclic loading. Li and Selig (1996) improved Monismith’s model by adding soil static strength parameters. Based on these models, Chai and Miura (2002) proposed a computational formula to predict the cumulative deformation of road subgrade soil under traffic loading. This formula, which takes into account the original state of soil, is expressed as