Study on the Deformation Failure Criterion of Stochastic Medium and Its Applications
|School||Central South University|
|Course||Road and Railway Engineering|
|Keywords||stochastic medium stress failure criterion deformation failure criterion underground excavation open pit excavation tunnel excavation safety estimation|
With the development of engineering construction in China, the safety ofengineering has become a more and more important issue. Nowadays, in order toestimate an engineering safety, it is essential to analyze not only the stabilizationextent or instable probability of rock mass and the relevant safety measurements fromthe point of rock strength but also the safety of the surroundings. Otherwise, it maybeinduces great economic losses. In the thesis, based on summarizing and absorbing theresearch achievements of the pioneer works and considering the shortage of rockstress failure criterion and the advantage of rock strain failure criterion, thedeformation failure criterion of stochastic medium is put forward. Furthermore, themovement and deformation of ground and rock mass induced by undergroundexcavation are studied systemically with the theory of stochastic medium. The mainresearch work of the dissertation can be summarized as follows:1. The deformation failure criterion of stochastic medium is put forward, whichcan avoid complex constitutive law and can be expressed only with strain. It canreflect the inherence deformation properties of the rock and soil and can be used toestimate engineering safety. In addition, the ultimate value of ground movement anddeformation and the protect level of constructions are expatiated on particularly,which provides bases for estimating the surroundings safety induced by excavation.2. The theory of stochastic medium is introduced briefly. Because the formula ofground movement and deformation can not be integrated, and they are used mostly intwo-dimension problems, computing methods of three-dimension problem for themovement and deformation of ground and rock mass are put forward with the theoryof stochastic medium. Based on the unit excavation, the formula for predicting themovement and deformation of ground and rock mass induced by thin rectangleexcavation are derivated, which consider the changing of excavation depth and thespread of excavation effects along the rock normal direction.3. The deformation failure criterion of stochastic medium is applied in theunderground mining engineering and the protect level of the affecting constructionsare expatiated on in detail. Based on the stochastic medium theory, formula for themovement and deformation of rock mass in a single section plane are derived, whichconsiders the horizontal and inclined section planes and the influence of coal pillar.Furthermore, the movement and deformation of rock mass induced by insufficientmining in the two orthogonal directions are discussed.4. According to the slice method, the formula for predicting movement and deformation of the ground and rock mass induced by inclined trapezium and prismoidcoal pillar excavation are derivated, which provide theoretical bases for the design ofcoal seam mining and coal pillar optimization.5. The deformation failure criterion of stochastic medium is applied in open pitexcavation engineering and the criterion for estimating the surroundings safety isprovided. The formula for predicting movement and deformation of the ground androck mass induced by many kinds of slopes excavation and foundation pit excavationare deduced. The conception of reducing coefficient of excavation effects are putforward, which can be used to study the properties of the slops or pits withreinforcements6. The formula for predicting movement and deformation of the ground and rockmass induced by tunnel excavation are deduced. Many cases are considered, such ashorizontal or inclined axes and many kinds of tunnel section shapes including circle,circular arch, ellipse, ellipse arch, and vertical wall and so on. The formula can beused in the single tunnel and many-hole tunnel.7 The program is developed to compute the movement and deformation of theground and rock mass, in which the functions including the all formula provided inthe thesis are defined. In the process of computing, it is convenient to plot lines onsome section or three-dimension figures in an area with the relevant functions and it iseasy to find the maximum of minimum of some variable.