超深基坑工程渗流耦合理论研究进展

Research Progress on Seepage Coupling Theory of Super deep Foundation Pit Engineering

摘要:

超深基坑工程的渗流耦合分析是岩土工程分析的重点和难点，涉及渗流耦合模型、渗流理论、土体渗透性以及降水对土体强度的影响等多方面的内容.在总结国内外有关基坑工程渗流耦合理论的基础上，对上述四个方面的内容进行分析、探讨.分析表明，超深基坑工程由于开挖深度深、开挖规模大、围护体系复杂，渗流耦合模型不仅要反映复杂的应力路径、土体的非线性特性，还要能反映渗流场与应力场相互耦合作用；在较高水力梯度作用下，超深基坑工程的渗流有可能偏离Darcy定律，由非饱和土饱和土不透水层组成的混合土层的渗透系数不再是一个常数，而是应变场的函数；试验表明，超深基坑工程降水对土体强度的影响不能忽略.探讨降水量与土体强度参数之间的定量关系是超深基坑工程渗流耦合分析的又一重要研究方向.超深基坑工程的渗流耦合分析迫切需要在渗流耦合模型、渗流理论、渗透系数动态变化等方面进行改进或创新，以满足工程实际的需要.

Abstract:

The seepage coupling model, the seepage theory, and the soil permeability as well as the influence of dewatering on soil strength were analyzed and discussed based on a summery of seepage coupling theory of foundation pit engineering at home and abroad. Results show that the seepage coupling model can not only reflect complex stress path and nonlinear characteristics of soil, but also can reflect the interaction of seepage field and stress field due to deep depth of excavation, large scale of excavation and complex retaining system of super deep foundation pit engineering. Under the effect of high hydraulic gradients, the seepage of super deep foundation pit engineering may deviate from the Darcy law, and the permeability coefficient of the mixed soil composed by unsaturated soil, saturated soil and water resisting layer is no longer a constant, but the function of strain filed. Test results show that the influence of dewatering of super deep foundation pit engineering on soil strength cann’t be ignored, therefore, it is an important research field about seepage coupling analysis of super deep foundation pit engineering that explores quantitative relationship between the amount of dewatering and strength parameters of soil. In conclusion, in order to meet the needs of engineering practice, it is urgent for seepage coupling analysis of super deep foundation pit engineering to make improvement and innovation in the seepage coupling model, the seepage theory, the dynamic change of permeability coefficients and so on.