输水工程中淡水壳菜侵蚀混凝土的机理研究

淡水壳菜附着在输水建筑物内壁会导致混凝土性能劣化,研究淡水壳菜附着规律与侵蚀混凝土的微观机理对建筑物防护对策的制定具有重要价值。本文研究了淡水壳菜在输水建筑物内部附着规律、足丝入侵机制、体长空间差异性;通过原位混凝土硬度、侵蚀深度测试,分析了淡水壳菜对混凝土物理性质的影响;基于侵蚀前后混凝土微观形貌、化学元素变化及XRD衍射图谱,解析了淡水壳菜对混凝土侵蚀的微观机理,提出了侵蚀后混凝土的物相转化机制。结果表明:淡水壳菜附着密度在渡槽内部自入口到出口呈现出衰减规律;在倒虹吸内部附着密度呈现出沿程波动特点,但总体稳定。淡水壳菜平均垂向分离力与体长呈正相关关系;淡水壳菜体长在大尺度空间上表现为“南方长,北方短”特点,相差10 mm,体长分布形式符合高斯分布。淡水壳菜长期附着下,混凝土硬度降低、侵蚀深度有所增加;微观形貌疏松多孔,Ca、Fe等元素流失;混凝土的侵蚀产物主要为二氧化硅。

The adhesion of Limnoperna fortunei to the inner concrete walls of a water transmission building causes the deterioration of concrete performance.Its adhesion law and erosion mechanism is of great value for the prevention and control of it.This study examines the behaviors of L.fortunei inside a water transmission building,focusing on its adhesion law,foot invasion mechanism,and spatial differences in length,and analyzes its influence on the physical properties of concrete through hardness tests and erosion depth tests on concrete in-situ.We reveal the micro mechanism of concrete erosion by L.fortunei based on a comparison of the micro morphologies,chemical element changes,and XRD diffraction patterns of the concrete before and after erosion;A phase transformation mechanism of the eroded concrete is suggested.The results show the attachment density of L.fortunei exhibits a decay trend from the inlet to outlet inside an aqueduct.Its attachment density inside an inverted siphon fluctuates along the way,but is generally stable;A positive correlation is observed between its vertical separation force and body length,and the latter features long in the south and short in the north in a large scale space,with a difference of 10mm.Under its long-term adhesion,a concrete surface suffers a decrease in material hardness and an increase in erosion depth;the micro morphology is loose and porous.Erosion causes a loss of Ca and Fe elements and creates silica,a major product of concrete.