Limit Analysis for Local and Overall Stability of a Slurry Trench in Cohesive Soil

Abstract

This paper uses limit analysis to develop a two-dimensional (2D) and a three-dimensional (3D) analysis of slurry trench local and overall stability for cohesive soil. Formulas for the slurry trench stability analysis are obtained through theoretical derivation based on limit analysis theory, and rotational mechanisms are then presented for slurry trench stability. For 2D slurry trench local and overall stability, the failure surface has the shape of a circular arc, whereas it has the shape of spherical cap for 3D local stability, and it has the shape of a torus with an outline defined by a circle for 3D overall stability. Examples are provided to illustrate the safety factor influenced by the slurry and soil bulk density ratio, slurry level depth and trench depth ratio, thickness of the weak soil layer, cohesion, and trench width and depth ratio. The safety factor for the 3D solutions is approximately 1.1 times greater than the safety factor for the 2D solutions for local stability but 1.2 times greater (B=h 5 1) for overall stability.

2D and 3D stability analysis of slurry trench in frictional/cohesive soil

“…The analytical upper bound solutions of this study are higher than those presented by Han et al (2012a). The friction angle φ>0° is the reason why the factors of safety obtained from this study are greater than those presented by Han et al (2012a).…”

“…In Figs. 3-5, and 7 the data points corresponding to φ=0° (cohesive soils), represent the solutions obtained by Han et al (2012a). The analytical upper bound solutions of this study are higher than those presented by Han et al (2012a).…”

“…In this section, the solutions obtained by Han et al (2012a) and Fox (2004) will be compared for various parameters, including γ sr /γ, h sr /h, c, φ and B/h. The results of these computations are graphically represented in Figs.…”

“…Based on the diaphragm wall construction of two open-cut metro stations, Xu et al (2011) studied the influence factors of stability of slurry trench sides during diaphragm wall building in soft soil by analyzing the fullness coefficient of slurry trenches corresponding to different controlling parameters. Based on the upper bound limit analysis theorem, Han et al (2012a) developed a 2D and 3D analysis of slurry trench for local and overall stability for cohesive soil. This paper is aimed at developing a 2D and 3D analysis of slurry trench stability for frictional/ cohesive soil.…”

Research Progress on Stability of Slurry Wall Trench of Underground Diaphragm Wall and Design Method of Slurry Unit Weight

“…When the foundation soil has a weak interlayer and poor bonding property (such as sand-cobble stratum) and when the seepage force of the slurry cannot maintain its balance with the pressure of the slurry wall trench soil, the slurry wall trench also experiences the local instability and often shows an overexcavation of pit [21], as indicated in Figure 1(b). Consequently, the filling coefficient of the concreting or impervious material increases, thereby increasing the construction cost and difficulty [22,23].…”