<p>The resilient modulus and Poisson's ratio of granular materials used in flexible pavement structures is highly nonlinear, stress/strain path and direction-dependent. Resilient properties are very important for realistic flexible pavement design. By far, several important aspects, such as the effect of stress path, major principal stress rotation, initial stress state and inherent fabric, on the cross-anisotropic resilient properties are not fully understood. The main objective of this thesis was to study the cross-anisotropic resilient properties of granular materials along various stress paths from both initial isotropic and initial anisotropic stress states. Extensive resilient modulus stress path tests were performed for this purpose. </p> <p> In this research, the resilient behaviour of the test material for initial isotropic stress states along various stress paths was investigated first, with particular interest in the stress/strain path dependency. New resilient modulus equations were then developed, by taking into account the effect of confining pressure and resilient strains. These equations can be used to estimate the cross-anisotropic resilient modulus corresponding to initial isotropic stress states. Selection of Poisson's ratio was also investigated. </P> <p> The effect of initial stress state on the resilient responses was studied through a series of stress path tests with constant confining pressure and constant vertical stress, respectively. Based on the experimental findings, revised equations for resilient modulus and Poisson's ratio were proposed to account for the effect of ratio of initial horizontal stress to vertical stress (Kini). The proposed equations can predict the cross-anisotropic resilient properties for various stress paths corresponding to initial isotropic/anisotropic stress conditions. </p> <p> In order to provide a more comprehensive insight into the complex resilient properties of granular materials along different stress/strain paths for various initial stress states, a micromechanics approach was introduced to back-calculate the degree of fabric anisotropy. The variations of fabric with stress path, initial stress state and final stress state (i.e., state which corresponds to the peak stress during cyclic loading) were investigated. To provide a reliable prediction of initial/inherent fabric anisotropy and fabric evolution in constitutive s with embedded microstructure, an evolution law of fabric anisotropy was developed. </p> / Thesis / Doctor of Philosophy (PhD)

The deep mining industry and civil engineering need to perform rock stability analyses during excavation projects. These analyses are closely related with displacements in tunnel contours. The ground reaction curve is a powerful tool to characterize these displacements that is widely used in the New Austrian Tunneling Method. However, the analytical solutions that exist are only applicable under isotropic stress conditions for deep tunnels. This study aims to investigate when it is possible using the analytical methods to determine the ground reaction curves with enough accuracy in the case of shallow tunnels under anisotropic in-situ stress conditions. The method begins with a literature study. After that, with the help of a 2D model, a comparison between the analytical and the numerical solutions for ground reaction curves at different depths and at different initial in-situ stress ratios was carried out. The results show that both crown and floor displacements deviate more from the analytical solution than the wall displacement. The crown and floor can even move upwards under high initial in-situ stress ratios for shallow tunnels. Because of that, the analytical solution of the ground reaction curve at shallow depths under anisotropic stress conditions should not be used. In the case of isotropic stress field conditions for the analysis in this study, the results given by the analytical solution agree with the numerical ones at depths higher than 14 times the radius of the tunnel. On the other hand, the difference between numerical and analytical solutions becomes higher while increasing the initial in-situ stress ratio, even for very deep tunnels. Furthermore, an empirical equation to obtain the displacements of the ground surface, tunnel wall and tunnel crown has been obtained after a multiple linear regression analysis.

This diploma thesis deals with problem of design and calculation of membrane structure of stadium roof. This is a complex engineering problem, which includes many partial problems: finding of initial form of membrane, statically and architecturally suitable arrangement of catenaries, economical solution of boundary conditions (foundations). All components affect each other and cannot be dealt without mutual coordination. It always greatly depends on the experience and intuition of engineer who design such structure. Task which cannot be resolved according to the theory of the first order. Equilibrium forces on the deformed structure, which in many projected structures gives satisfactory results, did not correspond to reality. It is therefore necessary to consider equilibrium of forces on the deformed structure according to the theory of large deformations. Diploma thesis was entered with regard to the intention of the companies Ing. Software Dlubal s.r.o. and FEM consulting s.r.o., working together to develop software RFEM. These companies plan to complement this program system with a module MEMBRANE for searching of initial shapes of membrane structures. This work is a contribution to the creation of this module.