Dynamic Prediction And Safety Evaluation Of A Deep Excavation In Chengdu Based On Monitoring Data Mining

The foundation pit monitoring itself is a kind of gray information problem,and the hidden information implied by the foundation pit problem is difficult to reflect from a single factor.The action result has become one of the main directions of foundation pit research in recent years.Combined with the deep foundation pit project of a subway in Chengdu,this paper considers all the general monitoring items of the current foundation pit project as the foundation pit safety evaluation index,establishes a prediction model based on the measured data of the monitoring project,excavates the foundation pit safety information,and establishes a safety evaluation system.Relying on a subway foundation pit project in Chengdu,this research mainly carried out the following research work:(1)Analyze the monitoring items according to the monitoring data,and summarize the model research on the changes of the monitoring results of the foundation pit: the horizontal displacement of the retaining piles is mainly changed from the initial parabolic displacement mode to the "spoon-shaped" displacement mode;the deformation of the neutral column In general,it can be summed up as having gone through four stages;the axial force of the steel support fluctuates greatly in the initial stage of installation,and tends to be stable in the later stage;the horizontal displacement of the pile top continues to increase with time but tends to be stable in the later stage.;the surface settlement presents different settlement variation laws according to the distance from the foundation pit;(2)Improve the prediction model,and explain the realization principle and practical application of this model in the prediction of deep foundation pits.The early prediction results of the improved GM-BP model are better than those of the BP model.The prediction result is better than the GM model,which improves the prediction effect;(3)In view of the current evaluation methods that only consider monitoring data such as deformation and ignore other monitoring information,establish a multi-index factor safety evaluation system,convert the monitoring data into risk quantities,and consider the consequences of the loss of hazard sources,construct an evaluation function function,and establish a basic Pit safety evaluation method;(4)Combine the prediction model with the evaluation method,use the prediction data to grasp the deformation and stress development of the foundation pit in advance,and apply the prediction result to the evaluation method to realize the advance evaluation of the safety evaluation of the foundation pit,which is the most lacking in the current research.of.Matlab is used to dynamically track the safety of the foundation pit reflected by the monitoring and prediction data of the foundation pit,and draw the dynamic change diagram of the safety assessment to realize the dynamic evaluation of the safety of the foundation pit.