干湿与冻融交替作用下渠道复合衬砌劣化规律研究

Study on the durability law of composite lining of canal under alternate action of wet-dry and freeze-thaw

渠道在季节性冻土区常年遭受基土冻胀、融沉和侵蚀的危害,针对此问题提出由聚苯乙烯泡沫板、陶砂和环氧树脂多层组合制成渠道衬砌垫层,采用室内干湿与冻融交替试验的方法来探究复合衬砌隔热性和粘结强度的劣化规律,以及多层组合垫层对混凝土板的保护作用,并结合统计学的方法确定陶砂最佳掺量。试验结果表明:陶砂能降低复合衬砌的导热系数,其隔热性劣化主要是由聚苯乙烯泡沫板和混凝土引起,随干湿与冻融累计试验次数增加呈线性降低趋势;陶砂掺量对聚苯乙烯泡沫板接触面的粘结强度基本无影响,而对混凝土接触面的粘结强度有较大影响,且掺量与粘结强度成反比例关系;在干湿与冻融交替作用下,多层组合垫层对混凝土板有较好的保护作用,与普通混凝土板相比,在质量与抗压强度损失方面分别降低1.04%和8.58%;以复合衬砌隔热性和聚苯乙烯泡沫板接触面粘结强度为双控目标,建立了陶砂最佳掺量的计算方法。多层组合垫层具有良好的隔热性、粘结强度和防渗效果,该试验研究成果可为渠道垫层设计提供科学参考。

Canals are damaged by frost heaving,thawing,and soil erosion in seasonal frozen soil areas.In this study,a canal lining cushion was proposed,composed of polystyrene foam board,ceramic,and epoxy resin,to alleviate the damage to the canal.In this study,the test method used was the alternating dry-wet and freeze-thaw test to investigate the degradation law of thermal insulation and bond strength of the composite liner.Also,this study investigated the protective effect of the multi-layered combined bedding on the concrete slab.Finally,this study determined the optimum admixture of ceramic sand by combining statistical methods.The test results show that ceramic can reduce the thermal conductivity of multilayer cushions.The thermal insulation of the cush⁃ion deteriorates,caused by the polystyrene foam board and concrete,and decreases linearly with the increase of test times.The ceramic content did not affect the bond strength of the polystyrene foam board interface.Howev⁃er,it greatly influenced the strength of the concrete interface,and the content was inversely proportional to the strength.Multilayer cushions had a better protection effect on concrete.Compared with ordinary concrete,EPconcrete reduced the loss of quality and compressive strength by 1.04%and 8.58%,respectively.The thermal insulation of the cushion and the bonding strength of the contact surface of the polystyrene foam board were tak⁃en as the control objectives,and the calculation method of the optimal amount of ceramic sand was established.The research results of this experiment can provide a certain reference for the design of the canal cushion.