坡体渗流与气温变化相关性分析

文章编号：1672-1683（2017）03-0158-06

Abstract：Based on the multi-phase flow & multi-field coupling theory，this paper adopted the finite element method to calculate the temperature distribution of Muyubao landslide as the atmospheric temperature changes.Further，it analyzed the influence of atmospheric temperature changes on the slope seepage according to the correlation between temperature and viscosity of water.The results of calculation showed that the effect of atmospheric temperature on temperature of the slope body is limited to the shallow surface；as the depth increases，the influence decreases and the hysteresis increases concurrently.The mobility of the water is affected by the change of the slope body′s temperature and it can change the water permeability in the inner slope.The effect of atmospheric temperature on permeability coefficient of the slope has a nonlinear relationship with depth.The effect of atmospheric temperature on the permeability coefficient declines as the depth increases.Generally，the permeability coefficient of the slope no longer change significantly when the depth is deeper than the maximum depth of infiltration.The permeability coefficient of the slope shows seasonal variation with the atmospheric temperature.The permeability coefficient decreases with the increase of depth when the atmospheric temperature is higher than the soil in summer.In contrast，the permeability coefficient increases with the increase of depth in winter.

Key words：air temperature；permeability coefficient；slope seepage；multiphase flow；seasonal

坡体渗流通常属于非饱和渗流的范畴，涉及到土（石）、水、气组成的多相物质的耦合作用[1]。坡体渗流通常与坡内水体渗透性、坡体初始含水率、渗透边界等诸多因素有关[2-3]，其中水体渗透性是影响坡体渗流的关键因素之一。水在土体中的渗透性主要受水的黏滞性、相对饱和度以及土体本征渗透性的影响[4]，而气温变化对土体本征渗透性以及相对饱和度的影响较小，因此气温变化主要通过改变水的黏滞性来影响坡内水体渗透性。在坡体温度场方面，许多学者做了大量研究并取得了丰硕的成果[2，5-10]。然而，较多研究者在计算坡体温度场时仅考虑了热量在土体中的传导，未考虑水、热耦合的热传输作用，导致坡体温度场计算结果不准确[11-12]。此外，部分研究者未能基于气温引起的坡体温度改变结果进一步计算其对坡内水体渗透性的影响[13-14]，常因温度变化不显著而得出气温变化对坡体渗流无影响的结论。本文基于多相流及多场耦合的理论和方法，完整地考虑了热传导、热传输及水热耦合效应，准确模拟坡体温度场分布，定量分析气温变化对坡内水体渗透性的影响。

1 計算模型

1.1 水、气、热传输控制微分方程

依据连续介质力学的基本理论及方法，将土体视为是由气、液、固三相介质组成的连续体，其内部水、气、热的传输在数学上可表述为基于时间和空间的偏微分方程描述。水（液相）在土体中的流动主要源于水压力梯度驱动，并受土体孔隙率、土体含水量以及水的黏滞性等因素影响，基于液态水的质量守恒可导出土体内水流动的控制微分方程[14]：

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