轻型挡土墙系统参数识别及损伤诊断研究

发布时间：2018-01-15 07:26

本文关键词：轻型挡土墙系统参数识别及损伤诊断研究　出处：《重庆大学》2013年博士论文　论文类型：学位论文

【摘要】：支挡结构是岩土工程中的一个重要组成部分，具有极其重要的地位。如果能够及时有效地对支挡结构进行健康监测，就可以对支挡结构的整体稳定性进行评估，进而可以避免人民群众的生命财产及国家的巨额基础设施蒙受巨大的损失。因此如何对支挡结构进行健康诊断，以确定支挡结构是否存在损伤，进而判别损伤位置、损伤程度和损伤变化趋势，是岩土支挡结构健康监测与安全评估系统的最主要问题。为此，本文在国家自然基金科学仪器基础研究项目“岩土支挡结构健康诊断仪的研制”(项目批准号：51027004)、教育部长江学者和创新团队发展计划项目“山区岩土工程”（项目批准号：IRT1045）的资助下对轻型挡土墙系统健康诊断问题展开了相关研究。基于理论分析、数值模拟和现场试验，对挡土墙系统的土体附加参数识别、动力指纹损伤识别法、人工智能损伤识别法和整体稳定性评价等问题进行了全面深入的研究，论文的主要研究工作如下： ①建立了轻型挡土墙系统动力响应的三维有限元数值模型，运用整体正交多项式法和特征系统实现法对挡土墙系统的模态特性进行研究。为了研究损伤对挡土墙系统模态特性的影响规律，详细分析了土体、挡墙的损伤程度、损伤面积和损伤位置对挡土墙系统的模态特性和幅值谱曲线的影响。 ②提出了悬臂挡土墙系统的简化动测模型，对土体附加参数的识别方法进行探讨。在模态参数识别的基础上，采用有限元优化设计方法识别土体的附加参数，对不同的组合优化方法、不同的目标函数的识别结果进行评价。并分析了土体附加阻尼对挡土墙系统简化动测模型的模态特性和动力响应的影响。 ③引入微分几何中的平均曲率概念，推导了适用于轻型挡土墙结构的损伤识别新指标：模态平均曲率差MMCD和柔度差平均曲率FDMC。以悬臂挡土墙为算例，，通过与其他三种损伤识别指标(频率变化率RF、振型变化率RD、高斯曲率模态差MGCD)进行对比分析，验证新指标对损伤的敏感性和有效性。损伤识别新指标能够准确的识别出挡土墙的损伤位置，继而评估挡土墙的损伤程度。 ④采用改进多种群遗传算法，结合挡土墙系统损伤时的特征方程，构造了能有效地同时识别出挡土墙系统损伤位置和损伤程度的方法：整体损伤识别法和分区损伤识别法。通过悬臂挡土墙不同损伤工况的识别结果，对两种识别方法的适用性、识别精度、计算效率和有效性进行了探讨。 ⑤对挡土墙系统整体稳定性“实时”评价方法进行研究，将挡土墙整体稳定性分为3个等级：稳定、基本稳定和不稳定。在挡土墙系统模态分析基础上，将土体等效成一系列弹簧来模拟，土压力统一表示为静止土压力和土压力增量之和，并假定土压力增量等于土体的地基反力系数和墙体位移的乘积，结合墙土共同变形，进行迭代计算得到土压力的分布形式。通过对库伦土压力理论、静止土压力理论和试验结果进行对比分析，验证所提出的土压力计算方法的可行性，从而进一步确定挡土墙系统的整体稳定性。
[Abstract]:The retaining structure is an important part in geotechnical engineering, is very important. If we can promptly and effectively carry out health monitoring of retaining structure, can evaluate the overall safety of retaining structure, which can avoid the huge infrastructure and national life and property of the masses of the people suffered huge losses so how to retaining structure health diagnosis, to determine the retaining structure is damage, and then determine the damage location, damage degree and damage trend of rock and soil retaining structure health monitoring and safety assessment system of the main problems. Therefore, based on the National Natural Science Foundation Project "basic research of geotechnical instruments the retaining structure of the instrument of health diagnosis development" (Grant No. 51027004), the Ministry of education program for Changjiang Scholars and innovative research team project "in geotechnical engineering" (project approval Number: IRT1045) under the support of retaining wall system health diagnosis related research has been carried out. Based on the theoretical analysis, numerical simulation and field test of soil additional parameter identification of the retaining wall system, dynamic fingerprint damage identification method, artificial intelligence damage identification method and whole stability evaluation are studied the main research work of this paper is as follows:
The establishment of three-dimensional finite element light retaining wall system dynamic response numerical model, using global orthogonal polynomial method and eigensystem realization method was used to study the modal characteristics of the retaining wall system. In order to study the influence of gear damage modal characteristics of wall system, a detailed analysis of the soil, the damage degree of the damaged area and the influence of the retaining wall the damage location on the modal characteristics and amplitude spectrum curve of retaining wall system.
The simplified model of dynamic measuring system of cantilever retaining wall, identification method on soil additional parameters. Based on modal parameter identification, additional parameters by using the finite element optimization design method for identification of soil, combination of different optimization methods, identification of different target function results were evaluated and analyzed the soil. The additional damping on the dynamic measurement model of the simplified modal characteristics and dynamic response of retaining wall system.
The concept of mean curvature in differential geometry, which is used to light the new block wall structure damage identification index: the average modal curvature difference MMCD and flexibility difference mean curvature FDMC. in a cantilever retaining wall for example, with the other three kinds of damage identification index (frequency change rate RF, modalchange rate RD, Gauss modal curvature difference MGCD) were analyzed to validate the new index sensitivity to damage and effectiveness. The new damage detection index can accurately identify the damage location of the retaining wall, and then evaluate the damage degree of the retaining wall.
The improved multi population genetic algorithm, combined with the characteristic equation of retaining wall system damage, the structure can effectively identify the retaining wall system and method of damage location and damage degree of overall damage identification method and damage identification method. Different partition wall damage condition by retaining cantilever recognition results, the applicability of two a recognition method of recognition accuracy, computational efficiency and effectiveness are discussed.
The research on the method of overall stability of retaining wall system real-time evaluation, the whole stability of earth retaining wall is divided into 3 levels: basic stability, stable and unstable. The retaining wall system based on the modal analysis, the soil is equivalent to a series of springs to simulate the soil pressure, expressed as the static earth pressure and soil the increment of the pressure, and assume that the product is equal to the earth pressure increment coefficient of subgrade reaction and wall displacement of soil, combined with the common wall soil deformation, distribution of earth pressure is obtained by iterative calculation. Based on the theory of Kulun earth pressure, static earth pressure theory and the test results were analyzed and verified the feasibility of the calculation method of earth pressure put forward, so as to further determine the overall stability of retaining wall system.

【学位授予单位】：重庆大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU476.4

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