高速明渠流条件下高性能加筋草皮抗侵蚀特性研究

Experimental studies of anti-erosion ability of high-performance reinforced turf on high-speed open channel

现有针对高性能加筋草皮的抗侵蚀性能研究,大多建立在大规模试验基础上,重点研究允许冲刷流速和表面切应力。为了研究高速明渠水流条件下高性能加筋草皮侵蚀过程,对天然草皮和3种高性能加筋草皮共48个样品进行培植,并布置在高速明渠流的倾斜水槽中,通过不同坡度和流量分别进行间断和不间断冲刷试验,分析流速、流量和侵蚀量的关系。结果表明,间断和不间断冲刷的侵蚀速率有明显差异,说明初始冲刷引起了高性能加筋草皮的大部分侵蚀。样本侵蚀过程显示侵蚀速率随侵蚀量的增加而降低,证明明渠高速水流作用下加筋草皮存在"侵蚀上限"特征。此外,还讨论了流量和生态加筋网结构对侵蚀过程的影响,并尝试拟合了平均侵蚀速率与水流表面流速的关系。

The high-performance turf-reinforced mat(HPTRM)is a new type of strengthening material which has been widely used in recent years to protect the vegetation linings and enhance their anti-erosion ability.The existing studies on the erosion resistance of the vegetated HPTRM systems are mainly based on the large-scale tests and focus on the permissible flow velocity and shear stress.In order to study the erosion process of the vegetated HPTRM system under the high-speed open channel flow conditions,a total of48specimens of natural vegetation and three types of vegetated HPTRM systems are cultivated.In a special flume designed to generate the high-speed open-channel flow,continuous and discontinuous flushing tests are carried out under different slopes and discharges.During the testing,the erosion depths of specimens,the flow discharges and flow surface velocities are recorded.The differences in erosion rates between the continuous and discontinuous tests indicate that the first flushing of the flow,which means the process of no flow to flow,induces most of the erosion of the vegetated HPTRM systems.The erosion processes of the specimens show a decrease of the erosion rate with the increase in the erosion depth,which proves the existence of the“upper limit”of erosion,which can be explained by the exposure of HPTRM and consequent increase of the anti-erosion ability.We have also discussed the influences of the flow discharges and HPTRM structures on the erosion processes,and try to fit the relationships between the average erosion rate and the flow surface velocity with the linear relationships.