基于模态柔度的软基水闸底板脱空范围识别

Identification methods of floor void of sluice on soft foundation based on theory of modal flexibility

软土地基上的水闸极易出现地基不均匀沉降、渗透变形等问题,进而诱发水闸底板脱空等灾害,现有的软基水闸底板脱空动力学诊断方法虽能识别脱空范围,但由于采用的基本模态参数(固有频率和测点振型系数)对水闸底板脱空的敏感性还需进一步提高,因此探究不同模态参数及其衍生量对水闸底板脱空的影响规律,确定更为灵敏的水闸底板脱空动力学敏感特征量具有重要意义。以对结构损伤更敏感的模态柔度作为水闸底板脱空动力学敏感特征量,建立了水闸底板脱空描述数学模型,并以各测点前两阶模态柔度变化率,改进了水闸底板脱空控制参数与模态参数(模态柔度)之间的响应面数学代理模型,将水闸有限元模型相应工况下的模态参数(模态柔度)与响应面数学模型计算模态参数(模态柔度)的相对偏差作为目标函数,将水闸底板脱空参数反演转化为目标函数的求解。以3种典型水闸底板脱空工况为例进行了验证,脱空反演结果与实际脱空范围的相对误差显著减小。模型提高了水闸底板脱空反演的精度,为软基水闸底板脱空检测和诊断提供了一种可靠的方法。

The sluice built on the soft soil foundation is prone to problems such as uneven foundation settlement and seepage deformation, which will induce disasters such as the sluice floor void. The existing soft foundation sluice floor vacancy dynamics diagnosis method can identify the void range. However, the sensitivity of the basic modal parameters(natural frequency and mode coefficient of the measuring point) to the sluice floor vacancy needs to be further improved. Therefore, the effect of different model parameters and their derivatives on the sluice floor vacancy needs to be further improved. To explore the influencing laws of different model parameters and their derivative quantities on the sluice floor vacancy, it is of great significance to determine the more sensitive characteristic quantities of venting dynamics of the sluice floor. The modal flexibility, which is more sensitive to structural damage, is taken as the sensitive characteristic of sluice floor void dynamics, and the mathematic model of sluice floor void description is established. The mathematical proxy model of response surface between sluice floor void control parameters and modal parameters(modal flexibility) is improved based on the change rate of the first two order modal flexibility of each measuring point. The relative deviation between the modal parameters(modal flexibility) of the sluice finite element model under corresponding working conditions and the modal parameters(modal flexibility) of the response surface mathematical model is taken as the objective function, and the sluice floor void parameter inversion is transformed into the solution of the objective function. The results show that the relative error between the inversion results and the actual void range is significantly reduced by taking three typical void conditions as examples. The model improves the accuracy of the inversion of sluice floor void and provides a reliable method for the detection and diagnosis of sluice floor void on soft foundation.