Study On Numerical Manifold Method And Application In Geotechnical Engineering

The numerical manifold method is a generalization numerical method, it is capable of uniformly dealing with the problem of continuous deformation and discontinuous deformation, and it has higher calculation precision for problem. At the same time, The numerical manifold method is based on finite cover, it is a simple and convenient resolvent for engineering problem. The numerical manifold method is pop method of research for the numerical method in geotechnical engineering. Aim at the theory and application of numerical manifold method, and combine the west traffic construction scientific and technical project "study on non-uniformed settlement mechanism of rock-fill embankment of red-bed", have researched the theory and application of numerical manifold method, works and research findings mainly has following aspects mainly: (1) Have research the effects of crack and boundary line in rock mass to the generation of cover system for numerical manifold method, put forward that mathematical cover must suit with crack and boundary line in rock mass, and put forward corresponding method that form the cover system for numerical manifold method; (2) Base on the composition of displacement function on manifold element, a new method of constraints treatment of fixed boundary is proposed, fixation constraint terms is strictly met by using corresponding cover function on the physical cover made up of the manifold element, deduce the corresponding numerical calculation format of manifold element's stiffness matrix and load matrix with fixation constraint terms; (3) Created numerical manifold model of fully bonded bar based on the limited cover technology of manifold method, this model is a new numerical model of bolt which use partially analytic displacement pattern. When use high-order cover function, it have feature of partial analytic solution and better calculation accuracy. At the same time, bolt and mathematics cover relatively independent, general grid can meet complex arrange of bolt, have eliminated the contradiction of mutual restriction between bolt disposal and grid partition in numerical simulation of bolt, and this model can consider to the case that exert prestressing force in anchor rod. This model can be used in simulating geotechnics bolt and analyzing the interaction of reinforcing bar and concrete; (4) Have research the simulation of excavation with numerical manifold method. Have research the treatment method of cover system and calculation method of unbalance force while simulate excavation with manifold method, and have research the simulation method for excavation while use high-order cover function, finally have made general course of simulation of excavation with manifold method. Have made the direct analysis and indirect analysis of excavation action, and have discussed their relation in detail. The manifold method have more merits than FEM while apply in excavation: â‘ based on cover technology, simple grid can meet the arbitrary course of excavation; â‘¡the direct analysis of excavation can give up the concept of released load, the simulation course is simpler and more natural and more reliable; â‘¢high-order manifold have better precision for excavation; (5) Aim at "study on non-uniformed settlement mechanism of rock-fill embankment of red-bed", research the coupling problem of numerical manifold method and DDA, put forward the simplified calculation method of the settlement after construction of full-rock embankment, used this completely discontinuous system study for rock fill problem for the first time, have disclosure microscopic the mechanism and law of displacement of fill-rock embankment in some degree. The simulation result display that the uneven and discontinuity of embankment displacement is obvious, it have greatly difference from condition considered rock fill as equivalent continuum. Have carried out numerical simulated analysis for the sensitivity of various factors that affects deformation of embankment, the reduction of friction coefficient between rock block and reduction of deformation parameter of rock have greater influence for deformation of embankment after construction, but the deformation form and law caused by them is different, the influence of reduction of rock block is very little. (6) Programmed the Object-Oriented program with C++ language in VC++ platform, it is capable of calculating the common problem of manifold method, fully bonded bar and excavation etc. The program have better preprocess and postprocess function. And the program have been proved correct by example. At the same time, programmed calculation program EDAnalysis according to "study on non-uniformed settlement mechanism of rock-fill embankment of red-bed", EDAnalysis have better preprocess and postprocess and the function of dynamic simulation.