Ferreira Fernanda Bessa, Pereira Paulo M, Vieira Castorina Silva, Lopes Maria de Lurdes
CONSTRUCT, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
Materials (Basel). 2021 Jun 4;14(11):3070. doi: 10.3390/ma14113070.
Geosynthetic-reinforced soil structures have been used extensively in recent decades due to their significant advantages over more conventional earth retaining structures, including the cost-effectiveness, reduced construction time, and possibility of using locally-available lower quality soils and/or waste materials, such as recycled construction and demolition (C&D) wastes. The time-dependent shear behaviour at the interfaces between the geosynthetic and the backfill is an important factor affecting the overall long-term performance of such structures, and thereby should be properly understood. In this study, an innovative multistage direct shear test procedure is introduced to characterise the time-dependent response of the interface between a high-strength geotextile and a recycled C&D material. After a prescribed shear displacement is reached, the shear box is kept stationary for a specific period of time, after which the test proceeds again, at a constant displacement rate, until the peak and large-displacement shear strengths are mobilised. The shear stress-shear displacement curves from the proposed multistage tests exhibited a progressive decrease in shear stress with time (stress relaxation) during the period in which the shear box was restrained from any movement, which was more pronounced under lower normal stress values. Regardless of the prior interface shear displacement and duration of the stress relaxation stage, the peak and residual shear strength parameters of the C&D material-geotextile interface remained similar to those obtained from the conventional (benchmark) tests carried out under constant displacement rate.
近几十年来，土工合成材料加筋土结构因其相对于传统挡土墙结构具有显著优势而被广泛应用，这些优势包括成本效益高、施工时间缩短，以及能够使用当地可得的质量较低的土壤和/或废料，如建筑和拆除（C&D）回收废料。土工合成材料与回填土之间界面处随时间变化的剪切行为是影响此类结构整体长期性能的一个重要因素，因此应予以正确理解。在本研究中，引入了一种创新的多级直剪试验程序，以表征高强度土工织物与C&D回收材料之间界面的时间相关响应。在达到规定剪切位移后，剪切盒保持静止特定时间段，之后试验再次以恒定位移速率进行，直至峰值和大位移抗剪强度被 mobilised。所提出的多级试验的剪应力-剪位移曲线在剪切盒被限制移动的时间段内显示出剪应力随时间逐渐降低（应力松弛），在较低法向应力值下更为明显。无论先前的界面剪切位移和应力松弛阶段的持续时间如何，C&D材料-土工织物界面的峰值和残余抗剪强度参数与在恒定位移速率下进行的传统（基准）试验所获得的参数相似。
