Secondary Development Of Loess Creep Model Based On FLAC^3D And Application On Time Prediction Of Landslide Sliding

In our country,more and more civil engineering projects are planned and constructed.The increasingly active engineering construction activities make scientific researchers pay more attention to the rheological properties of geomaterials.In the early days the rapid development of coastal urban construction has promoted the research on the rheological properties of soft clay,and the related research has achieved rich results.Because the national strategy of “the Belt and Road” is proposed and promoted by government in recent years,northwest district located in the loess plateau ushers in new development opportunities.The construction of a large number of infrastructures will make the study of loess rheological properties become urgent and valuable.The study of soil time-dependent stress-strain characteristics mainly includes two aspects,on the one hand is the experimental study;the other is the numerical calculation model theory research,namely constitutive model and its application.Based on a large number of relevant literature reports,the research progress of soft clay rheological characteristics and loess creep characteristics are delved,and those results which many scholars put forward are detailedly summarized in this paper.The author chooses the loess creep characteristics to study according to the current progress of loess research,which the soil rheological properties contain four main research contents.With C++ programming language a component model's secondary development is carried out in the FLAC3 D through integrated development environment.At the same time,the time prediction which the loess landslides occur unstable failure are studied through combining the creep model and the catastrophe theory.The main work of this paper includes the following aspects:(1)The progress of the research on soft clay and loess is summarized in detail.Focused on the introduction: indoor rheological laboratory tests of soft clay,the research results of rheological constitutive model theories;research situation on creep characteristics of loess.The theoretical models and experimental studies put forward by the scholars are summarized.(2)On the basis of comparative study,the author choose the Nishihara model,and extend the expression of one-dimensional constitutive model into threedimensional form.Then the calculating formula of stress increment is deduced by viscoelasticity theory,and developed by VISUAL STUDIO Environment to achieve the secondary development in FLAC3 D.The experimental data were fitted by ORIGIN software,and the DLL file that is generated through secondary development in VISUAL STUDIO were validated.(3)In this paper,the application of catastrophe theory in geotechnical engineering is studied.Combining loess creep constitutive model with catastrophe theory,loess landslide is analysis,which Burgers model is used to describe the mechanical characteristics of loess,and the potential function of loess landslide is established by combining catastrophe theory.The nonlinear evolution of the loess landslide which the constitutive relation of the sliding surface medium is composed of the strain softening model and the element model is discussed.The time prediction formula of loess landslide unstable failure is given.