A critically tapered active accretionary wedge was simulated using a numerical analysis of plastic slip-line theory to understand the mechanics of morphologic evolution. The concept of critical state soil mechanics was applied to describe the entire wedge area overlying a basal décollement fault. Presuming a condition of two-dimensional plane strain along the compressional direction, we obtained the numerical solution of conjugate plastic slip lines at a critical state of stress defined by the Coulomb yield criterion. The velocity vectors were obtained by applying the associate flow rule with the boundary conditions at the upper surface of the wedge. Finally, the detachment was determined from the effective stress condition inside the wedge and the sliding friction coefficient along the fault. Our numerical simulations demonstrate that the morphology of a critically tapered wedge is dependent on the frictional strengths of both the wedge materials and the basal fault. The critical taper angle decreases with increasing internal friction angle and decreasing basal friction coefficient. The results also revealed that the pore pressure controls the morphology of the accretionary wedge for cohesive sediments but not for non-cohesive materials. The effect of pore pressure on the morphology of a critically tapered accretionary wedge becomes more significant as the cohesion increases. Assuming that the cohesion is very low, we could infer the ranges of strengths that most observed wedge geometry data have 0.3–0.6 for the basal friction coefficient and ~35–45° for the internal friction angle of the wedge materials.

中文翻译：

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液压机械约束临界锥形增生楔形几何形状的数值模拟

使用塑性滑移线理论的数值分析模拟了临界锥形主动增生楔，以了解形态演化的机理。应用了临界状态土壤力学的概念来描述基底脱层断层之上的整个楔形区。假设沿压缩方向的二维平面应变条件，我们获得了由库仑屈服准则定义的临界应力状态下共轭塑料滑移线的数值解。通过将关联流规则与楔形上表面的边界条件一起应用来获得速度矢量。最后，根据楔子内部的有效应力条件和沿断层的滑动摩擦系数确定脱离。我们的数值模拟表明，临界锥形楔的形态取决于楔材料和基底断层的摩擦强度。临界锥角随内摩擦角的增加和基摩擦系数的减小而减小。结果还表明，孔隙压力控制粘性沉积物的增生楔形貌，但非粘性材料则不然。随着内聚力的增加，孔隙压力对临界锥形增生楔形貌的影响变得更加明显。假设内聚力很低，我们可以推断出强度范围，大多数观察到的楔形几何数据的基础摩擦系数为0.3-0.6，楔形材料的内摩擦角为〜35-45°。