Research on Integrated Geohazard Prevention in Tangshan City

The potential geohazards threatening the Tangshan city consist of earthquake and other hazards such as karstic collapse,ground subsidence caused by coal mining,and etc.The characteristics and influence factors of main geohazards in Tangshan city are analyzed,and the integrated model and forming mechanism of geohazards are investigated.The destruction effects of geohazards in Tangshan city,are controlled by many factors,the relationship of which cannot be expressed as linear functions.Potential risks of geohazards are related to seismic movement,fracturing of bed rock,karstic collapse,site category and landform.Since quantitative relationships among these influence factors are difficult to be obtained using traditional methods,the multivariate nonlinear model based on artificial neural network is employed.With this model,the distribution of geohazard risks in Tangshan city is calculated with reasonable precision.In the calculation,the learning coefficient is taken as 1.2,the inertia coefficient as 0.5,the number of hidden layer as 2,the number of elements as 6 in No.1 hidden layer,and 3 in No.2 hidden layer.The geohazard risk of Tangshan city is evaluated and the distribution of geohazard risk is investigated.The results show that the geohazard risk of Tangshan city is greater than that most other areas by 40 percent,even by 70 percent greater than some local areas.Also,it is found that the geohazard risk decreases gradually from southeast to northwest.Finally,the influences of geohazard risk distribution on city planning and engineering construction are analyzed and some suggestions are given for these purposes.