接触面法—切向应力非线性分布的梯形渠道冻胀力学模型

Frost-heaving mechanical model of trapezoidal canal considering non-linear distribution of normal/tangential stress on interface

针对开放系统下的寒区梯形渠道,考虑衬砌各点地下水补给条件的横向差异提出非线性分布法向冻胀力的计算方法,通过引入冻土与衬砌接触界面切向相互作用的Winkler假设导出非线性分布切向冻结力的计算方法,进而构建接触面法-切向应力非线性分布的梯形渠道冻胀力学模型。以塔里木灌区某梯形渠道为例,分析了不同地下水埋深w对各截面弯矩的影响规律。结果表明:地下水埋深越浅,则衬砌板截面弯矩分布的不均匀性越强,最大弯矩的量值迅速呈非线性增大,坡板危险截面位置约在距坡脚30%~42%坡板长处,底板危险截面在渠底中部附近,与调查结果相符。同时分析了顶盖板约束下不同接触面切向刚度(k_(p))对各截面切向位移及切向冻结力分布的影响规律。结果表明:切向位移及切向冻结力均自坡顶向坡脚处逐渐增大,在坡顶处为零,在坡脚处达到最大值。k_(p)较小时,截面切向位移及切向冻结力趋于线性分布;随着k_(p)的增大,两者逐渐偏离线性分布,且k_(p)越大两者非线性分布越明显。研究结果可为寒区梯形衬砌渠道抗冻设计提供参考。

For trapezoidal canals in open water transfer systems,a novel method for calculating the distribution of non-linear normal frost-heaving force was proposed considering the horizontal difference of distance to groundwater table of each test point.Then Winkler assumption of the tangential force on the interface of frozen soil and lining was introduced to derive a calculation method of the distribution of non-linear tangential ad-freezing force.Eventually,a frost-heaving mechanical model of trapezoidal canal considering non-linear distribution of normal/tangential stress on the interface was constructed.Taking a trapezoidal canal in Tarim Irrigated Area as an example,the influence of groundwater table buried depth w on the distribution of section moment of concrete lining was analyzed by this model.The results show that the smaller the w is,the more non-linearly and rapidly the maximum value of section moment increases with heterogeneous distribution;sections of slope plate which are vulnerable to frost-heaving damage are located at the positions of 30%-42% slope plate length away from the slope toe,and those of the bottom plate are in the periphery of the bottom center,these findings are consistent with the field investigation results.A parameter analysis was carried out on the tangential displacement of each section and tangential ad-freezing force with different tangential stiffness coefficient of contact interface k_(p).The results indicate that the magnitude of both tangential displacement and tangential ad-freezing force gradually increase from the slope top to toe,which is zero on the slope top and maximum on the slope toe.when k_(p) is small,both the tangential displacement and tangential ad-freezing force show the tendency of linear distribution;as k_(p) gradually increases,both of them gradually deviate from linear distribution,and the larger the k_(p),the more non-linear the distribution.The study can provide references for frost-heaving resistance design of trapezoidal canals in cold regions.