【作者】 张晔；

【导师】 刘国华；

【作者基本信息】 浙江大学 ， 水利工程， 2010， 硕士

【摘要】 大坝从种类上分有土石坝、混凝土重力坝、混凝土拱坝等,然而每一种坝由于监测项目和监测目的的不同,采集的数据种类也不尽相同,因此数据分析模型也不尽相同。虽然大坝观测资料分析技术层出不穷,但是目前我们很难找到一个具体的分析某一类型的大坝监测数据的专用软件。因此,本文将在总结现有大坝观测资料分析方法,尤其是混凝土坝应力应变观测资料分析方法的基础上,研制一套应力应变观测资料分析软件。应力应变观测是研究工程工作状态以及估计工程安全状况的重要方法之一。但由于混凝土不仅有自由体积变形,而且在长期应力作用下,还产生徐变变形,所以不能直接用弹性应力应变关系计算混凝土的实际应力,必须研究混凝土自由体积变形和徐变变形对应力的影响。本文的工作内容如下：①混凝土的变形及应力分析混凝土内一点的总应变包含两个部分：一部分是外力和内部约束力引起的应变称为应力应变；另一部分是自由体积变形引起的应变,称非应力应变。计算应力所用的应变应为从总应变中减去非应力应变,才是产生应力的应变。自由体积变形是不受外力作用的混凝土,其体积将由于温度和湿度的变化以及水泥的水化作用而不断地变化而产生的变形,它包括三部分,即混凝土自生体积变形,混凝土温度变形以及混凝土湿度变形。这种变形可以由无应力计测量出来。②应力应变观测及资料的误差处理观测值除含有测读误差和量测设施的系统性误差外,不可避免地还含有外界因素引起的波动。后者往往大于测读误差,并难以预知和控制。这种波动有时包括某些次要因素扰动变化的影响。如果直接引用上述个别测值作为分析依据,可能会掩盖或歪曲数据的实际变化规律。由于这类波动对观测序列而言一般表现为随机性或伪随机性,在将测值提供应用之前可通过合适的误差处理方法予以削弱,使处理后测值比较符合观测序列的整体规律。本文采用统计检验法和五点应变平衡法对观测数据误差进行处理。③实际应力计算方法研究混凝土的实际应力是应力—应变观测的最终成果,用以研究混凝土坝的应力分布,评价大坝的安全性和经济性。经过误差检验和修正的应变观测资料计算成单轴应变后就可以计算混凝土单向实际正应力。由于考虑徐变影响的方式不同,计算方法不同,本文主要采用变形法、应力松弛法进行实际应力计算。④基于经验模态分解的混凝土自由体积变形提取混凝土内的实际应力是根据单轴应变增量逐步累加求得,而单轴应变又是根据实测总应变扣除自由体积变形而得到。在实际工程中,总应变是根据应变计或应变计组测得,而自由体积变形则是根据无应力计测得。由于施工的原因,以及大坝运行过程中的多种不确定性因素的存在,无应力计测值和应变计组测值很难同时出现。本文采取经验模态分解方法从应变计总应变中提取出混凝土自由体积变形,从而解决了在缺少无应力计测值情况下常规分析方法无法计算的问题。更多还原

【Abstract】 The dam is classified into earth and rock-fill dam, concrete gravity dam, concrete arch dam, and so on. Due to the difference of monitoring projects and monitoring purposes, the kind of the collected data is distinguishing for each kind of the dam. As a result, the models used to analysis the data are different. Up to now, though enumerate many analytical methods on the observation data can be enumerated, the software specialized in some kind of the dam can not still be found. So, in this paper, after summarizing the existing methods, especially on the concrete dams, a set of software specialized in observation data of the concrete dams is produced.The stress strain observation is an important method used to study the working order and evaluate the safe condition of the engineering. As the existence of the free volume deformation and the time deformation, the actual concrete stress can not be got from elastic stress-strain model directly. We must study that the free volume deformation and the time deformation influence on the stress. So the following are what we have done.1 The Concrete D eformation and Stress AnalysisThe total strain of some point in concrete includes two parts:one part is called the stress strain produced by external loads and internal sanction; the other is called the non-stress strain produced by the free volume deformation. We can get the stress strain through subtracting the non-stress strain from the total strain.The free volume deformation includes three parts, such as self-grown volume deformation, temperature deformation and humidity deformation. The free volume deformation can be measure by non-stress gage.2 S tress S tain O bservation and E rror R eductionThe observation data includes the fluctuate produced by external factor inevitably besides measurement error and system error. The latter is usually greater than the former, and is difficult to predict and control. If the fluctuate is used to analysis, the true changing law can not be got. Before they are used, they must be reduced. In this paper, statistical verification method and 5 points strain balanceable method are used to reduce the error.3 S tudy on C alculation method of Actual StressThe purpose of the stress stain observation is to study the stress distribution of the dam. After error reduction, the strain observational data can be used to get the uniaxial strain which we can get the actual stress through with the help of some methods, such as deformation method and relaxation coefficient method in this paper.更多还原