长输水隧洞局部阻塞的瞬变响应机理及动态诊断理论研究

Partial obstruction of water supply tunnel is usually the result of the infarct of rock, concrete and sediment, which is usually caused by earthquakes, landslides and siltation etc. Partial obstruction may have some potential effect on the ability of discharge flow and the pressure distribution, as well as cavitation damage in water supply tunnel. With the development of water transfer construction, the tunnel is more and more widely used in water transfer projects, and partial obstruction is also increasing in practice projects. It is very significant for operation and management department to diagnose timely the location and intension of obstruction. In order to prevent and mitigate the harm caused by partial obstruction, the research will focus on the interference mechanism of transient response of partial obstruction. Based on the distribution of extreme transient pressure, the regulation and diagnosis model of partial obstruction are expected to establish in the program. The leading researches is following: (1) Based on the theoretical and mathematical model, transient process will be obtained by numerical simulation, and the interference mechanism of transient response will be particularly studied for partial obstruction in water supply tunnel. (2) The program will study the distribution of extreme transient pressure during the changing process in operation. In order to detect the location and intension of obstruction, the diagnosis model will be established for the tunnel which subjected to obstruction.(3) An hydraulic experimental model will be designed and conducted, which is important to verify the above theoretical and mathematical diagnosis model in location and intension of obstruction. Moreover, the application of diagnosis model will be optimized through the experimental research.

输水隧洞的局部阻塞是指由于岩石破碎、衬砌塌落等在隧洞中形成阻塞，导致局部过水断面缩小而阻碍水流的现象。它可能导致隧洞输水能力降低，输水线路的局部压力异常，以及空蚀空化等诸多安全隐患。随着调水工程大量兴建，隧洞的使用越来越广泛，隧洞阻塞现象也日趋增多，如何及时检测和排除局部阻塞导致的安全隐患，成为运行和管理部门较为关注的问题之一。为了防止和减轻局部阻塞导致的危害，本项目将研究局部阻塞对瞬变响应的干扰机理，并依据瞬变极值压力分布的变化规律，建立输水隧洞局部阻塞的定位诊断模型。主要研究内容包括：（1）研究输水隧洞局部阻塞对瞬变响应的干扰机理，建立瞬变响应的理论及数学模型，采用数值计算获取瞬变响应过程；（2）通过隧洞运行调度过程中的瞬态压力的极值变化规律，建立阻塞的定位诊断系统，对阻塞的位置和大小进行诊断分析；（3）通过试验对瞬变响应模型及定位诊断模型进行检验，并优化输水隧洞局部阻塞的检测方法。

在输水隧洞中，岩石破碎、衬砌塌落等在隧洞中形成局部阻塞通常会导致隧洞过水断面减小，不仅影响隧洞的过流能力，而且造成输水线路局部压力异常。局部阻塞的存在也将导致阻塞点附近的瞬变压力急剧升高和降低，增加隧洞的水毁隐患，对线路的安全运行造成潜在威胁。通常情况下，局部阻塞的检测需要在停水放空情况下进行人工检查和定位诊断，这会影响输水工程的正常运行，并且消耗大量的人力物力。如何及时检测和排除局部阻塞导致的安全隐患，成为运行和管理部门较为关注的问题之一。为了防止和减轻输水管路中由于岩石破碎、衬砌塌落等局部阻塞导致的危害，本项目通过理论推导、数值模拟和试验测试等方法研究了局部阻塞对瞬变响应的干扰特性，通过数值方法获得了管路沿线压力波动和最大最小极值压力分布曲线。基于无阻塞情况下水锤的极值压力沿线分布，获得阻塞后极值压力的沿线变异特性。研究表明，局部阻塞导致的极值压力增量在阻塞点附近最大，逐渐向管道两端呈线性衰减，根据极值压力增量的线性分布特性，建立了极值压力检测情况下的区间阻塞的预测模型，通过实验测试对理论分析和数值模型进行了验证。研究的主要成果包括：（1）从理论上分析了局部阻塞对管路输水的影响，通过阻塞面积和阻塞率等参数对局部阻塞进行了理论概化；（2）对隧洞阻塞下的瞬变响应进行理论分析和数学建模，建立了局部阻塞的瞬变响应数学模型，通过数值计算方法对数学模型进行求解，并获得局部阻塞情况下管路的瞬变响应过程。（3）通过对极值压力增量的线性化处理，建立了局部阻塞的区间预测模型，并对局部阻塞的强度进行诊断；（4）建立了水力模型试验对局部阻塞情况下的瞬变流响应过程进行测试和分析，验证了理论和数值模拟的可靠性。项目的研究成果丰富了局部阻塞的健康诊断的理论和方法，可供相关工程问题进行借鉴和参考。