Analysis Of Expansive Soil Tunnel Based On The Improved Nonlinear Grey Markov Forecasting Model

During the process of tunnel construction,safe construction and quality performance are closely related to stability of surrounding rock deformation.Instability of surrounding rock is one of the tunnel engineering accidents,therefore,this is an important engineering problem.Nowadays,more and more scholars in the tunnel construction and infrastructure construction companies pays more attention to the deformation monitoring of the surrounding rock.There are several methods for predicting the deformation of surrounding rock:empirical coefficient method,safety coefficient method,numerical method.In the actual civil engineerings,the above method is widely used,but for the tunnel engineerings,numerical simulation method,the tunnel surroundings rock's complexity and unpredictability,which makes the method only can be used as the theoretical reference for practical engineering.So,a large number of engineering scholars focus on the mathematical analysis methods,one of the important system method about the tunnel surrounding rock deformation is Gery System.In this thesis,we will analyze the tunnel surrounding rock deformation by Gery System theory.This thesis is supported by the National Natural Science Foundation of China: Research on mechanical behavior of expansive surrounding rock tunnel during torrid and rainy whether.Item number: 51368014.Using Guangxi Nanning expansive soil as raw material to establish the solid tunnel model.Monitoring the deformation data of tunnel surrounding rock by simulating extreme rainfall climate condition.Analyzing expansion data about deformation of surrounding rock by the classical grey theory and modified Markov model.According to the data which measured in different days,analyzing the deformation of tunnel surrounding rock by two methods.Comparing the predicted data and measured data,selecting the days of the stability of the surrounding rock,draw the comparison chart of the predicted data and the measured data,and determine the final stability time of the surrounding rock.Based on the measured data of the deformation of the surrounding rock,the advantages and disadvantages of the classical grey prediction model and the modified nonlinear Markov model are analyzed and discussed,elaborating the two forecasting methods.GM(1,1)model in the grey prediction theory is an important prediction model has the advantages of simple structure,operability and other advantages can be built according to the model of a small amount of data,but the model is used to predict the volatility of the data,the predicted results are compared with the actual data,which will be some deviation,the predictive data with time the changes caused some errors.The modified nonlinear Markov model deals with sample data,optimizes the background value of the model,Corrects the prediction results by introducing Markov chain model.The improved prediction model not only mines rules optimization of the change data from the original data,but Uses state transition probability matrix to analyze the trend of data.In this way,the application range of the grey theory in the tunnel engineering will be widened,It can also improve the accuracy of the prediction results of surrounding rock deformation effectively.The location which has a small amount of engineering geological materials and complex external factors can determine the general support time of the second lining by the deformation prediction model proposed in this thesis.By this method,it can provide a certain guidance foe the actual construction schedule of the tunnel and the implementation of the second lining.