对滑坡防治工程相关规范中渗流问题的研究

渗流对滑坡稳定性至关重要，在松散堆积层滑坡稳定性评价中如何正确反映渗透力的作用是岩土工程界近年来讨论的热点。目前涉及滑坡防治工程的有关国家规范已经考虑渗流的影响，但在渗透力的重复计算上存在突出的问题，一些重要的概念和原理亟待从源头上进行澄清。文中以流体力学的基本理论为依据，从渗透力概念定义的微观源头上，证明了渗透力是一种等效力。在非压缩流体条件下，无论稳定流还是非稳定渗流，渗透力与浮力的共同作用效果与周边孔隙水压力是完全等效的。针对滑坡渗流模型，从宏观上再次证明了上述等效性原理，且表明在流网比较简单的条件下，采用渗透力计算比较简便，论证了更为严格的条件下条分法的下滑力中应考虑渗透力和浮力的影响。在此基础上，对现有规范的稳定性评价和滑坡推力计算方法进行了修正，定性和定量地评价了现行规范评价方法的偏差对滑坡设计推力和工程造价影响的程度。实际算例表明，现行规范的设计推力偏大5 %以内，主体工程造价偏大幅度基本与此相当，并略低。

Study of seepage flow for Chinese design codes of landslide stabilization

The seepage flow is one of the critical issues to the stability of landslide. In recent years, how to correctly reflect the effect of seepage force during the stability analysis of loose accumulational landslides has been the focus of geotechnical engineering. Certain Chinese design codes, which considered the effect of seepage flow, have a prominent problem in redundant computation of seepage force and pore water pressure. Based on the theory of hydromechanics, this paper has proved that the resultant force of seepage force and buoyant force is identical to that of ambient pore water pressure. Not only in steady seepage, but also unsteady seepage, the equivalent principle is tenable. As a special case, the proof process of this equivalent principle for loose accumulational landslide in seepage flow condition is suggested. This paper also proves the superiority of the calculation method using seepage force in a simple flow net condition, as well as the necessity of concerning the effect of seepage force and buoyant force in the calculation of the sliding force for landslides. This paper has revised the methods of stability analysis and sliding force calculation for the design codes. Furthermore, the impact of the deviation effect for certain design codes have been qualitative and quantitative evaluated. Finally, an engineering example illustrates that the result of the design thrust and the construction cost of landslide support project, which are given by unrevised design codes, is 5 % -or-less higher than necessary.