Study On Mechanical Effect Of Filling Rate On High Filling Airport Project In Mountain Region

This paper combines the current typical engineering practices on high filling projects of Chinese airports in mountain region and the basic theory of the effect of loading rate on the geotechnical engineering characteristic,puts forward the mechanical effect of filling rate of high filling project.Using advanced theory and method of the modern geotechnical engineering and rock mechanics,combining with the modern mathematical theory,laboratory testing technique,numerical simulation technology,in-situ monitoring technology and the computer programming technology,this paper systematic studies the mechanical effect of filling rate of high filling project from the two aspects of rheology and consolidation and establishes a set of more perfect technology system on the mechanical effect of filling rate.This research result have made progress both in basic theory and method,and in applications,solve the problem of controlling the filling rate.The main contents and results are studied as follows:(1)The characteristics of high filling projects of Chinese airports in mountain region are systematically summarized.According to the model theory of “three integration” as the basic object,4 typical high filling models are further proposed.And the filler on the technical aspects include mechanical properties and construction characteristics and so on are comprehensively summarized.Foundation is laid for the systematic research of high filling projects.(2)Based on the formula derivation of creep on the linear Newtonian element,the influence of loading rate on the creep is showed clearly on constitutive relation.By using different methods of loading,the creep variable values of various kinds of loading methods are calculated from the theoretical formula of mechanics,and it is proved that fast loading creep variable is greater than slow creep variable.(3)The constitutive model for the engineering filed has been discussed.With the analysis of the creep characteristics of Cvisc cohesive-elastic-plastic model and the application of the engineering,a new degenerated Cvisc cohesive-elastic-plastic model has been proposed in this paper.It is based on the Cvisc cohesive-elastic-plastic model and the degeneration process of the original model.(4)On the basis of the existing Barron theory of sand-drained consolidation and with the consideration the continuous loading conditions,then a consolidation equation with the consideration of well resistance,smear effect has been deduced and a simplified equation which is applicable in the engineering application has been proposed.(5)Based on continuous loading consolidation equation and theoretically derived temporary slope stability coefficient formula of saturated soil filling.It is shown that this depends not only on gravity loading,depending in the consolidation degree,slope stability with the filling velocity and filling lasted showed the dynamic characteristics.At the same time,the concept of critical height is redefined,and the critical height is determined on the stability factor,and the process and method of determining the critical height of construction are put forward.(6)Taking the typical soft-rock filling high fill project a study,by using laboratory test,numerical backdeduction analysis and model identification,creep parameter and constitutive model were determined.Using numerical simulation technology and according to the 4 filling rate simulation calculation result,mechanical effect of filling rate of soft-rock filling high fill project is studied and the filling rate has a significant effect on the rheological properties of soft-rock high filling project is proved.At the same time,combining with the in-situ monitoring data,the filling rate has a significant effect on slope stability that too high the filling rate is will form the creepage sliding-tension fracture mechanism and even the development of the formation of sliding-tension one.Studies show that the soft-rock filling high filling projects should be slow and medium rate filling.(7)Using numerical simulation technology and according to the 2 filling rate simulation calculation result,mechanical effect of filling rate of hard-rock filling high filling project is studied and the filling rate has no effect on the rheological properties of hard-rock high filling project is proved.It shows that the hard-rock filling high filling projects can be high rate filling.(8)In order to study the typically saturated high filling foundation,the influence which is caused by the velocity of filling on temporary slope stability is researched.A procedure to calculate excessive pore pressure by the consolidation of sand-drained ground equation with continuous loading condition is designed.Three kinds of filling rate and degree of consolidation are calculated and the slope stability coefficient at every time is calculated.Simultaneously,the stability coefficients of slope with several different filling rate in different filling depth is given.Studies show that,the filling rate has great mechanical effect on the saturated high filling foundation,and also have direct influence on the slope stability and the critical height,the project should be medium rate filling.