College of Civil Engineering, Tongji University, Shanghai, China.
School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiaotong University, Shanghai, China.
PLoS One. 2019 Jan 25;14(1):e0211312. doi: 10.1371/journal.pone.0211312. eCollection 2019.
A geotextile mattress with sloping curtain is a newly proposed countermeasure against river and estuarine scour. In previous laboratory experiments, a geotextile mattress with sloping curtain was capable of protecting the bed downstream from scour and stimulating sediment deposition on both sides. However, the seepage scour under its geotextile mattress is inadequately researched at present. In this study, the Geotextile Mattress with Sloping Plate (GMSP) is proposed based on the simplification of the geotextile mattress with sloping curtain with the construction feasibility considered. A series of experiments was conducted to investigate the pressure distribution around the GMSP and the averaged seepage hydraulic gradient beneath its mattress. The results indicate remarkable pressure difference on two sides of the GMSP. The minimum bed pressure appears about 1.3 times the plate height downstream to the GMSP. The averaged seepage hydraulic gradient beneath the mattress increases with the sloping angle increasing from 35° to 60° in general. The averaged hydraulic gradient also ascends as the relative plate height increases, but reduces as the opening ratio increases at opening ratios greater than 0.143. The safety boundary for the averaged hydraulic gradient under the geotextile mattress of the GMSP could get much smaller than the critical hydraulic gradient of piping and can easily be overwhelmed. This phenomenon can mainly be attributed to the discontinuous contact between the mattress and the seabed. A suggestion for the parametric design of the GMSP is to extend the width of the mattress to reduce the risk of seepage failure.
一种带有倾斜幕帘的土工织物床垫是一种新提出的对抗河流和河口冲刷的对策。在以前的实验室实验中，带有倾斜幕帘的土工织物床垫能够保护下游床免受冲刷，并刺激两侧的泥沙沉积。然而，目前对其土工织物床垫下的渗流冲刷研究不足。在本研究中，基于简化带有倾斜幕帘的土工织物床垫并考虑施工可行性，提出了带有倾斜板的土工织物床垫（GMSP）。进行了一系列实验来研究 GMSP 周围的压力分布和其床垫下的平均渗流水力梯度。结果表明 GMSP 两侧存在显著的压力差。最小床压出现在距 GMSP 下游约 1.3 倍板高的位置。平均渗流水力梯度一般随倾斜角度从 35°增加到 60°而增加。平均水力梯度随相对板高的增加而上升，但在开口比大于 0.143 时随开口比的增加而减小。GMSP 土工织物床垫下平均水力梯度的安全边界可以远小于管涌的临界水力梯度，并且很容易被超过。这种现象主要归因于床垫与海底之间的不连续接触。对 GMSP 进行参数设计的建议是延长床垫的宽度以降低渗流破坏的风险。
