Study Of Tidal Deterministic Model And Hybrid Model For Seawall Osmotic Pressure Safety Monitoring

The seawalls are important hydraulic structures with the intention of withstanding typhoon, rainstorm and astronomical tide. Its security is directly related to the security of people’s life, property and the urban economy. Since the founding in 1949, the typhoon has met astronomical tide many times, some of which make part of seawall damage and bring us enormous economic loss. With the development of national economy, the importance of seawall construction and its safety monitoring receives more and more attention.Seawall is built along the coastline. With the influence of tide, which changes time after time, its internal flow is unsteady seepage problem. Seawall safety monitoring starts late, so it has not formed the theory system. In the study, it is not good to entirely use the experiences of reservoir dam. It is very important to deeply study the seepage law of seawall and the mathematical modeling method on seawall safety monitoring, since it is of great significance to master the running state of seawall.In this paper, a section of Shanghai Pudong New Area seawall is taken as an example. On the basis of previous studies, seepage finite element calculation is accomplished by using the finite element software ANSYS and wrtiting the calculation program of seawall unsteady seepage in parametric programming language APDL. And the osmotic pressure values of measured points were obtained. Then by analyzing these values and measured tide level values, the lag property of calculated osmotic pressure is discussed. Against this view, the early tide level, which is close to them, was selected as basic factor of tide deterministic model. The factors of model are given in power series forms. The tide deterministic model is given by stepwise regression analysis. On the basis of tide deterministic model, aging action is considered in the course of building hybrid model. The hybrid model is also built by stepwise regression analysis. In the hybrid model, tidal component is calculated by finite element method. Time dependent component is given by statistical methods. Multiple correlation coefficient, residual standard deviation, average relative error and average relative prediction error values of the two models are calculated and analyzed. Example shows that, the two models can well reflect the seepage state and predict osmotic pressure of measured points, which can implement effective monitoring and prediction of seawalls osmotic pressure.In this paper, since the described hybrid model is built on the basis of the tide deterministic model and aging action is considered in the course of building model, compared to the tidal deterministic model, the model is more comprehensive in the aspect of reflecting the influence factors and more conducive to obtain accurate fitting and prediction effect of seawall osmotic pressure.