黄土的冻胀融沉作用对水利设施的病害分析

Analysis of the Damage of Water Conservancy Facilities Caused by Frost Heaving and Thawing Settlement of Loess

季节性冻土区内,黄土的冻胀融沉受多种因素影响,冻结温度引起冻结深度和水盐迁移变化,影响冻胀融沉发生的程度,反复的冻胀融沉作用会对高标准农田灌区水利设施产生不同程度的危害,影响水利设施的正常使用。以陕西省宝鸡市千阳县高崖镇高标准农田灌溉区的黄土为研究对象,利用COMSOL数值仿真模拟软件研究了不同冻结温度状态下黄土冻结深度的变化规律,通过室内冻结试验,分析了冻结温度对水盐迁移及冻胀融沉的影响,探究了多因素条件下黄土的冻胀融沉作用对高标准农田水利设施产生的危害,并提出了相应的防治措施。结果表明:冻结温度降低时,冻结温度梯度增大,水盐迁移量增大;土层冻结深度随冻结温度的降低而加深,即一定温度范围内,冻结温度越低,土层冻结深度越大,冻胀融沉的影响范围越大,土体扰动范围越大,对高标准农田水利设施产生的危害就越大;采取“水盐热隔离法”,可隔离水盐迁移,降低水盐迁移对黄土冻胀融沉的影响,从根本上解决冻胀融沉对水利设施产生的病害。

In seasonally frozen soil areas,the frost heave and thaw settlement of loess are influenced by various factors.The freezing temperature causes changes in freezing depth and water salt migration,affecting the degree of frost heave and thaw settlement.Repeated frost heave and thaw settlement can cause varying degrees of harm to the water conservancy facilities in high standard farmland irrigation areas,affecting the normal use of water conservancy facilities.Taking the loess in the high standard farmland irrigation area of Gaoya Town,Qianyang County,Baoji City,Shaanxi Province as the research object,the variation law of loess freezing depth under different freezing temperature states was studied by COMSOL numerical simulation software.Through indoor freezing experiments,the influence of freezing temperature on water and salt migration and frost heave and thaw settlement was analyzed,and the harm of loess frost heave and thaw settlement to high standard farmland water conservancy facilities under multi factor conditions was explored,and the corresponding prevention and control measures were put forward.The results show that as the freezing temperature decreases,the freezing temperature gradient increases and the amount of water and salt migration increases.The depth of soil freezing deepens with the decrease of freezing temperature,that is,within a certain temperature range,the lower the freezing temperature,the greater the depth of soil freezing,the greater the impact range of frost heave and thaw settlement,the greater the disturbance range of soil,and the greater the harm to high standard agricultural water conservancy facilities.Adoption of“water and salt thermal isolation method”can isolate the migration of water and salt,reduce the impact of water-salt migration on loess frost heave and thaw settlement,and fundamentally solve the diseases caused by frost heave and thaw settlement on water conservancy facilities.