Abstract
Surcharge slopes are more vulnerable to instability under the effects of earthquake ground shaking, especially considering the tensile stress. In order to account for the adverse factors of seismic forces and tensile stress, the theory of soil with tensile strength cut-off is deduced and analyzed using the upper bound limit analysis method in this paper. Combined with the quasistatic analysis, the equation of critical acceleration expression for surcharge slope subjected to the dynamic conditions has been evaluated. By using the improved Newmark method, permanent displacements have been analyzed in the case of the classical earthquake ground motions. In addition, optimization algorithm has been undertaken, in which several influencing factors such as slope inclination, internal friction angle, surcharge factor, seismic load, and tension cut-off coefficient have been taken into account, and some results are verified with the classical solutions and FEM results. The results concluded the following: (1) The outcomes of verification results are accurate. (2) The critical acceleration of the slope is significantly affected by tension cut-off with the increasing of surcharge factor and seismic effects. (3) The permanent displacements of surcharge slope considering the tensile strength cut-off can be even 2 times of the traditional analysis; meanwhile, with more reduction of tensile strength, the cumulative displacements increase rapidly. Therefore, considering the influence of tensile strength cut-off is fundamental to the dynamic stability design of surcharge conditions.
Highlights
Earthquake is one of the most destructive geological disasters in nature
In the framework of the upper limit theorem of limit analysis, Chang et al [21] proposed a method to solve the permanent displacement of slope with rotating failure surfaces. e rotation logic diagram is shown in Figure 10 and the calculation process is described as follows: when the seismic coefficient K exceeds the critical acceleration Kc, the block begins to slide
Based on the kinematic theory of limit analysis, this paper described the detailed theoretical analysis of slope with tension cut-off and studied the effect of surcharge on the stability of slope under seismic conditions
Summary
Earthquake is one of the most destructive geological disasters in nature. When an earthquake occurs, it has a tendency to induce secondary disasters such as landslides and rockfalls, creating a chain of disasters, which threatens social economy and human lives; many scholars have been studying and analyzing the seismic slope stability consistently. Park et al [11] studied the influence of the tensile strength variation on the slope stability and fracture morphology, based on the upper bound limit analysis, and optimized the strength envelope in the classical M-C criterion with circular-arc curve He et al [12] discussed the safety factor and permanent displacement of slope with the tensile strength cut-off under seismic load; the research combined with the quasistatic method and the Newmark slider method and results showed that, for vertical slopes subjected to seismic loads, the safety factor is reduced by 55%, and the slope displacement caused by the earthquake is approximately twice that obtained with the consideration of Mohr-Coulomb (M-C) yield criterion. The research selected measured ground motions to analyze the influence of various surcharge factors and tension cut-off factors on slope stability, according to the case of slope failure in the earthquake
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