农业工程学报2018，Vol.34Issue(8)：100-108,9.DOI:10.11975/j.issn.1002-6819.2018.08.013
考虑冻土双向冻胀与衬砌板冻缩的大型渠道冻胀力学模型
Mechanical model for frost heave damage of large-sized canal considering bi-directional frost heave of frozen soil and lining plate frozen shrinkage
摘要
Abstract
In vast and cold permafrost regions, concrete lining canals are highly vulnerable to frost heave damage because of the freezing and expansion of foundation soil. Frost heave deformation of canal foundation frozen soil is orthotropic, namely bi-directional frost heave. Bi-directional frost heave of foundation soil consists of frost heave both parallel to temperature gradient direction and perpendicular to temperature gradient direction. As large-sized concrete lining trapezoidal canals have larger cross-section dimension and longer canal slope lining plate than ordinary canals, the mechanism of frost heave damage of large-sized canals is different from medium or small sized ones. Both storage effect of tangential frost heave force along canals concrete lining plates and frozen shrinkage stress of canals concrete lining plates are significant. The reasons for frost heave damage of canals concrete lining plates in cold regions consist of frost heave of canal foundation frozen soil and frozen shrinkage of canals concrete lining plates. As low rainfall and no water diversion in winter in north-western cold and arid regions in China, initial moisture content of canal foundation soil is extremely low. In specific regions with specific meteorological conditions and soil quality conditions, groundwater replenishment becomes dominant influence factor which determines frost heave intensity of each point on canal concrete lining plates. By combining Winkler elastic foundation assumption for canal foundation frozen soil and considering orthotropy of frost heave deformation of frozen soil namely bi-directional frost heave of frozen soil, calculating methods to determine distribution of normal frost heave force and tangential frost heave force on canals concrete lining plates in open-system conditions were proposed. Eventually calculation formulas of internal force of canal concrete lining plates were carried out. Analytic formulas to calculate frozen shrinkage stress of canal lining plates were deduced based on elastic foundation beam theory, and methods for crack resistance checking computations of canal lining plates of large-sized concrete lining trapezoidal canal were proposed. By taking a trapezoidal canal in Gansu Jinghui irrigation district as prototype, the distribution of internal force and frozen shrinkage stress of each section of lining plates were determined. Then the distribution of maximum tensile stress (namely, tensile stress on upper surface of canal lining plates) on canal lining plates and the position coordinate of the most dangerous section were calculated. Contrast analysis results between the situation considering both bi-directional frost heave and frozen shrinkage stress and the situation only considering normal frost heave force irrespective of frozen shrinkage stress showed that the calculated value of maximum section tensile stress according to the latter was notably less than the previously calculated value. Therefore, taking no consideration of the effects caused by bi-directional frost heave of canal foundation frozen soil and lining plate frozen shrinkage in mechanics analysis and frost heave resistance designs of large-sized concrete lining canal was unsafe. While considering both bi-directional frost heave and frozen shrinkage stress, the maximum cross-section tensile stress on shady-slope plate was 2.134 MPa. While considering normal frost heave only and irrespective frozen shrinkage stress, the maximum cross-section tensile stress on shady-slope plate was 1.494 MPa. Thus it can be seen that the calculated values would be smaller if considering normal frost heave only and irrespective frozen shrinkage stress. The research results can provide references for mechanics analysis and frost heave resistance designs of large-sized concrete lining canal.关键词
渠道/应力/模型/冻土工程/双向冻胀/冻缩应力/衬砌渠道/力学模型Key words
canal/stress/models/frozen soil engineering/bi-directional frost heave/temperature stress/concrete lining canal/mechanic model分类
农业科技引用本文复制引用
肖旻,王正中,刘铨鸿,王羿,葛建锐,王兴威..考虑冻土双向冻胀与衬砌板冻缩的大型渠道冻胀力学模型[J].农业工程学报,2018,34(8):100-108,9.基金项目
国家重点研发计划"水资源高效开发利用"重点专项(2017YFC0405101) （2017YFC0405101）
国家自然科学基金(51279168) （51279168）
国家科技支撑计划(2012BAD10B02) （2012BAD10B02）
博士点基金项目(2012020411100254) （2012020411100254）
