含贯通管缝岩土体Navier-Stokes流耦合non-Darcy流的拖曳力效应

Continuous fracture and pipe are primary hydraulic channels to transfer surface water into underground water, as well as to connect underground water with rock and soil matrix. The continuous fracture (or pipe) sometimes plays a key role in case that failure occurs in rock mass and soil. Presently, scholars and engineers in the field of civil engineering primarily consider pore water pressure, seepage force, softening and deterioration due to water when evaluating stability of the buildings constructed in or on rock mass and soil according to the forced standards and classic theories of rock and soil mechanics. Even so, however, failures and disasters still occur in some buildings that should have enough safety in theory. Therefore, this work presents that the effect of drag force widely existing in movement of groundwater should not be neglected in case that the flow in continuous fracture (or pipe) is accompanied by seepage in rock and soil matrix. Accordingly, a nonlinear mathematic model based on micro-scale is used to describe the movement of groundwater in rock mass and soil containing the continuous fracture (or pipe). This model assumes that Navier-Stokes flow passes through continuous fracture or pipe along with non-Darcy seepage in porous rock or soil matrix. Use of the given method could reveal the characteristic of flow field and distribution of flow shear stress in rock mass and soil. Meanwhile, the theory methods could be validated together with analysis for a series of physical models and project cases. In addition, using the present method the drag force could be embedded into the existing limited analysis theory. Also the fluid shear stress could be directly added to effective stress during numerical calculation. This work would help in quantitatively evaluating the contribution of drag force to the mechanical responses of rock mass and soil so as to reasonably calculate the stability and safety of the buildings constructed in or on rock and soil in condition of seepage.

贯通管缝既是地下水、地表水和岩土体之间水力联系的重要通道，也是岩土体失稳破坏常常追踪的边界条件。然而，当前评价地下水渗流环境下一些建（构）筑物的稳定性时，依据现有的规范标准和经典的岩土力学理论，考虑岩土体渗流力、孔隙水压力以及遭受的软化、劣化作用，安全储备理应能得到保证，但有时仍出现失稳破坏甚至灾变事故。据此推断：伴随贯通管缝水流的拖曳力效应不容忽视。有鉴于此，申请项目从细观尺度入手，针对含贯通管缝岩土体Navier-Stokes流耦合non-Darcy流的细观描述难题、拖曳力对岩土体的力学响应难以定量问题，建立可求解的非线性渗流数学模型，来揭示含贯通管缝岩土体组合介质的流场特征和流体切应力分布。基于理论计算、试验测试和案例反馈的一致性检验，从而实现拖曳力嵌入岩土体极限平衡稳定分析理论、切应力纳入基于有效应力原理的数值计算理论构架，为科学评价渗流条件下建（构）筑物的稳定性提供理论基础。

岩土体中的贯通与非贯通裂缝、管道（统称“管缝”）和孔隙结构共同构成一个复杂的多孔网络体系。其中，贯通管缝是地下水与地表水相互转换的主要路径，是地下水与岩土体之间水力联系的重要通道，也是岩土体失稳破坏常常追踪的边界条件。然而，学术界工程界评价地下水渗流环境下一些建（构）筑物失稳破坏时，依据现有的规范标准和经典的岩土力学理论，仅考虑岩土体渗流力、孔隙水压力及遭受的软化、劣化作用，却出现难以阐释的困惑，据此推断：伴随贯通管缝水流的拖曳力效应不容忽视。鉴于此，申请项目拟从细观尺度入手，建立含贯通管缝岩土体多孔介质Navier-Stokes流耦合non-Darcy流的非线性数学模型，通过理论计算、试验测试和案例反馈一致性检验，揭示含贯通管缝多孔介质内的流场特征和流体切应力分布，量化拖曳力对岩土体的力学响应贡献，为科学评价渗流环境下含贯通管缝岩土体多孔介质中建（构）筑物的稳定性提供理论基础。