【作者】 唐天国；

【导师】 刘浩吾；

【作者基本信息】 四川大学 ， 岩土工程， 2005， 博士

【摘要】 工程结构(建筑、市政、地下工程、边坡工程…等等)的破坏都是由局部损伤开始,经积累、扩展而导致失事,由此往往造成灾难性后果。为预防工程安全事故,工程结构的无损检测和健康监测具有重要意义,以便及时发现早期损伤、防患于未然。动力检测是建筑结构等类型的工程结构的无损检测领域的发展重点。鉴于工程结构损伤的复杂性和动力检测识别的难度,动测技术水平尚不能满足工程需要。本文采取理论分析与模型试验密切结合的技术路线,大力开展跨学科研究,以对危害最大的梁结构裂缝损伤为研究对象,首次提出了2 种新的动测技术——模态应变能法和虚拟柔度矩阵法。对裂缝梁损伤进行了系统的动力有限元分析(可看作一种数值试验),按相似理论完成了两个不同比尺、不同材料的动力模型试验,由数值分析特别是模型测试中获得翔实系统的数据,为理论研究和方法验证提供了数据基础和手段。运用人工神经网络的最新进展和相关成果,构建了结构裂缝损伤识别的BP 模型,用以实现动态数据的处理和识别。岩体工程类型(如边坡工程、坝基工程等)的破损失事以滑动、滑坡为主,岩体为天然地质体(动测法对其无能为力),故岩体工程检测多采用传感技术的安全监测。鉴于常规岩土工程监测技术的局限性,发展了分布式光纤滑动传感技术,运用土工大三轴试验首次完成了光纤传感监测岩体滑动和钢-砼界面滑移的2 种模型试验,获得滑距-光损耗关系方程。 本文的主要创新成果是: (1)首次提出结构损伤检测的模态应变能法,以模态应变能为检测指标和更多还原

【Abstract】 Engineering structures, such as buildings, public works, underground works and slope engineering are destroyed from local damages, which accumulate , and enlarged and wrecked, The effect of structure failures are catastrophic. To preventing safety accidents, nondestructive detection and health monitoring of engineering structures are high meaningful, which could discover early damages and take preventive measures. The dynamic detection technique is one of important nondestructive detection methods. The damages shape of engineering structures are complicated, and their effective detecting is difficult, and the effectiveness of the dynamic detection technique is still not satisfactory. In this paper, the beam with crack damage is investigated and 2 dynamic detection techniques including the modal strain energy method and the virtual flexibility matrix method are presented. The beam with crack is systemically analyzed by the dynamic FEM. Based the similarity principle, dynamic experiments of two modals with different scales and different materials are completed. A large amount of detailed data are obtained from the model experiments, which provide data and means with theoretical research. BP modal of the artificial neural network(ANN) has been built. It realizes dynamic identification of structural damages. Rock engineering and dam foundation. It damages mainly by sliding. Rock mass is natively geologic materials and can’t detect by dynamic techniques. Rock safety monitoring is usually detected by sensors. Because standard monitoring technique is not defective for the with geotechnical engineering, the distributed optical sliding sensing technique is developed and 2 model tests are carried out to detecting rock mass sliding and steel-concrete interface damage. The relation equation of sliding distance-optical loss is obtained. There are some creative results in this paper . Firstly, the modal strain energy method is put forward. Its detection index is the modal strain energy. The theoretic idea is that the change of strain field local crack damages and energy field profoundly and directly. Crack location is determined by modal strain energy change before and after structure cracking and crack depth is determined by frequency perturbation change. Results of dynamic model tests and numeric simulation show that the strain energy index is very sensitive to crack damages and the method is predominant. Secondly, the virtual flexibility matrix method is presented for structure’s damages. Unit virtual force is exerted on component elements and generalized strain changeable ratios of the undamaged and damaged structures are obtained. The relation is built between flexibility matrix and damaged element, and the damage location and damage severity can be determined. Using few modal parameters could achieved better precision, which coincides with actual engineering conditions. The method do not need numeric model parameters such as mass matrix. Hunce the numeric model errors have no influence on identification results. This physical meaning of the method and its computation speed are simple. Model tests approved this method of highly precision for damage location and damage severity could be estimated. Thirdly, the BP network model is constructed for data processing and damage identification. A intelligent method is built. For tests data processing ,BP model is convenient, high accurate and suitable to engineering practice. Fourth, model tests of distributed optical sensing for rock mass sliding and steel-concrete interface sliding monitoring are realized by the triaxial shear test of soil. The difficulty of optical-mechanics data collection to instantaneous brittleness fracture of the solid material is solved. The data and relation curve for slidingdistance-optical loss are obtained. The probability of typical application of the optical-fiber sensing to geologic disaster monitoring and safety monitoring of slope engineering and dam foundation, and steel-concrete interface damage has been showed.更多还原