【作者】 贾彩虹；

【导师】 吴中如； 顾冲时；

【作者基本信息】 河海大学 ， 水工结构工程， 2002， 硕士

【摘要】 本文针对老坝出现防渗帷幕逐渐老化、坝体裂缝再生和扩展等影响渗流的现象，应用渗流有限元、神经网络、数理统计等方法，结合坝工理论，对老坝渗流的数学监控模型、防渗帷幕对坝基渗流场的敏感性、坝体裂缝渗透系数和水头差对坝体渗流的敏感性以及老坝渗流监控指标的确定方法等进行了分析研究。主要研究内容如下： 1．在分析水位和降雨对渗流滞后效应的基础上，深入研究了老坝渗流的数学监控模型，建立了基于滞后效应的渗流统计模型；此外，建立了反映非线性映射的神经网络模型，并利用神经网络的权值大小，综合评价了环境量对渗流效应量的影响程度。 2．采用三维渗流有限元的数值试验方法，通过改变帷幕渗透系数，研究了帷幕工作性态变化对坝基渗流场变化的敏感性；研究了帷幕渗透系数(K)对幕后扬压力折减系数(α)和灌浆廊道渗流量(Q)的影响，并建立了k与α、k与Q之间的关系式。 3．探讨了裂缝渗透系数k和等效宽度b的计算，并运用数值模拟方法研究了裂缝工作状态和水头差变化对坝体渗流场的敏感性；研究了裂缝渗透系数(k)和水头差(ΔH)对裂缝渗流量(Q)的影响，建立了Q与k、ΔH之间的关系式。 4．对拟定渗流监控指标的常规方法、置信区间法和小概率法进行了探讨；利用时效分量法，并结合监控指标，对老坝渗流的转异性态进行了判别。更多还原

【Abstract】 In consideration of the aging of impervious curtain and the reclamation and expansion of crack of dam body and their influence on the seepage flow of the aging dams, the mathematical and mechanical knowledge, such as seepage FEM, artificial neural network, probability statistics, together with the knowledge of dam engineering, are introduced into this dissertation. The mathematical monitoring model of seepage flow, the sensitivities of .the impervious curtain to the seepage flow of dam foundation and the crack to the seepage flow of dam body, the methods of determinating the monitoring indices and distinguishing the abnormity of the seepage flow are researched separately. The main contents are as follows:1. Based on the analysis of the hysteresis effect of water level and rainfall on the seepage flow, the monitoring models of seepage flow of aging dams are researched, and the seepage statistical model based on hysteresis effect is established. In addition, the neural network model with non-linear mapped capacity is established, and the influence degree of the environment data on the observation data is estimated comprehensively by using the power value.2. Using the numerical test method of the 3D-FEM of seepage flow, the sensitivity of the impervious curtain working status to the seepage flow of dam foundation is researched by changing the permeability coefficient of the curtain. The influences of the permeability coefficient k on uplift pressure reduction factor a and on the seepage discharge of grouting gallery Q are analyzed. Accordingly, the expressions of k and a -. k and Q are obtained.3. The determination of permeability coefficient k and the equivalent width of crack is discussed. The sensitivities of the crack working status and head difference AH to the seepage flow of dam body are researched by using the numerical simulation method. The influences of the permeability coefficient k and head difference AH on the seepage discharge of crack are researched, and the expressions of Q and k, AH are obtained.4. The methods of determinating the seepage monitoring indices, such as general method, confidence region method, little probability method, are discussed. The abnormity of the seepage flow of the aging dams is distinguished by time-dependent exponent together with monitoring indices.更多还原