盐渍侵蚀条件下土工袋材的劣化损伤规律

Degradation damage regularity of geosynthetic material under saline soil erosion

为探究盐渍土壤环境对砌护农田排水沟道土工袋材的侵蚀影响,以宁夏北部引黄灌区典型盐渍土壤类型为依据,在实验室分别设置了土工织物在碱性、硫酸盐、氯盐以及盐碱复合溶液中的长期浸泡和干湿循环侵蚀试验,通过测定试样的单位面积质量、抗拉强度以及试验前后的厚度等指标随时间的变化值,并与蒸馏水浸泡的基准试样进行对比分析,研究了不同服役工况下土工袋材的耐久性与劣化损伤规律。结果表明:蒸馏水与碱性溶液中,袋材的单位面积质量和厚度变化很小,断裂强度保留率分别在99%和97%以上,说明聚丙烯土工袋材具有良好的耐水浸泡和抗碱性能;硫酸盐、氯盐对土工袋材的劣化损伤与耐久性有一定影响,溶液盐分含量越大,劣化越严重,且硫酸盐对袋材侵蚀劣化的影响较氯盐显著;干湿循环使入渗孔隙通道及渗透速率增大,会加剧袋材的劣化,且盐溶液因水分蒸发、结晶,产生顶破力,劣化更明显。研究结果可为土工袋技术在盐渍灌区治理农田排水沟道边坡及类似工程提供参考依据。

In order to explore the deterioration characteristics of geosynthetic material subjected to aqueous saline solution erosion in salinized irrigation area where the slope stability of agro-drain is protected with the geotextile soil containers,the erosion experimental scheme has been conducted including drying-wetting cycle and long-term immersion tests that consist of immersion in distilled water,alkaline,sulfate,chloride and saline-alkali aqueous solution,etc.The mass per unit area,tensile strength and initial-finished thickness of the samples have been measured in variation with time,and the effects of salting on the degradation and durability of geotextile material under different service conditions were studied by comparing with the benchmark sample from immersion in distilled water.The results show that in distilled water and alkaline solution,the mass per unit area and thickness of the bag material change little,and the retention rate of breaking strength is above 99%and 97%,respectively,so it shows that the polypropylene sewing geotextile bags have good resistance to water immersion and alkali resistance;sulfate and chloride salts have a certain impact on the deterioration and durability of the geotextile material.The higher the salt content of the solution is,the more serious the deterioration is,and the sulfate will affect the bag material.In other words,the effect of bag material erosion and deterioration is more significant than that of chloride salt.The dry-wet cycle increases the infiltration pore channel and infiltration rate,which will exacerbate the deterioration of the bag material,and the salt solution produces bursting force due to water evaporation and crystallization,which makes the deterioration more obvious.The research results can provide a reference for geotextile soil containers technique to treat the slope sliding of agricultural drainage channel and similar projects in saline irrigation areas.