To ensure the surrogate model is more reliable, the ranges of the design variables should be as wide as possible. The finite element method was modified so that it can predict a factor of safety having the same definition as in limit equilibrium. Therefore, how to design the cavern roof and predict the stability of natural gas storage cavern in bedded rock salt are always hot issues in the engineering field Liang et al. The latter is actually also a discrete approach of importance for rock mechanics and rock engineering. The construction of a new cavern modifies the state of stresses and displacements in a zone around the existing cavern. Courtesy Rocky Mountain National Park. Chapter 4 discusses the application of the theory of linear viscoelasticity in solving problems of stable behaviour of rocks and soils.
The town of Estes Park in Colorado was severely damaged by the Lawn Lake flood, and a summary of events can be found at. The concepts of rheology of a continuum. Stability solutions taking into account of water seepage were presented and compared with those without considering seepage. The soil nail mechanical contribution to the tunnel face stabilization is taken into account at the design stage by an equivalent increase of effective cohesion in the improved ground mass. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Moreover, sliding on bedding planes is the dominant failure mode, and the properties of the discontinuities play a key role in the instability of the considered rock slope.
For the analysis of the ultimate limit state and the estimation of the safety factor, the numerical approach can still be effective provided that a suitable technique is adopted to lead the soil-structure system to a failure condition. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. The canyon shape, gradient of dam slope and height of the dam significantly influence the 3D effect. The book is in two separate parts. In addition, by using four methods of stabilization including soil nailing, anchor, reinforced retaining wall with geogrid and gabion, the slope stability has been analyzed by investigating and comparing the coefficient of safety factor and reliability, deformation and failure mechanism and also, the economic analysis of construction in two cases without and with stabilization. Wiley, New York, 2013 , p.
The finite element method is generally accepted as a tool for assessing the serviceability limit state for geotechnical structures whereas the factor of safety at the ultimate limit state is more commonly determined by conventional limit equilibrium methods. The performance and the specific advantages of the innovative technique are discussed also on the basis of results from on site testing. The results show that the factor of safety converges after a few iterations. It presents some new solutions and methods which include both static and kinematic aspects of the problem, and some original effective methods for investigating media of limited cohesion. The present analysis of the filtration theory equations should help interpret effective parameters of the non-steady filtration model. Chapter 3 gives the actual properties of soils and rocks determined from experiments in laboratories and in situ.
The assumed density distribution function specifies the microstructure used in deriving the failure criteria and damage evolution rules for specified deformation histories. In particular, the limit states are specified for engineering problems, such as embedded anchor plate pull-out and rigid tool penetration into the material. This technique is adapted here for use with the non-linear Hoek-Brown failure criterion, an empirical approach to estimating rock mass strength. Here the movement of water is regarded as the cause of deformation of the rock or soil skeleton and the consolidation theory developed on this basis is presented in a novel formulation. To evaluate the accuracy of the shear strength reduction technique in determining slope stability, the factors of safety obtained with this technique were compared to those obtained using limit analysis solutions for a homogeneous embankment. It was found that in the case of ordinary concrete the pronounced transverse isotropy was developed due to an oriented damage growth. To this end the standard cubical specimens of the concrete and fiber concrete were subjected to uni-axial compression.
Discrete model for rocks and soils. The entire activity can be repeated for the flood of 2013 using Fig. Moreover, back analysis of a failed or failing slope can be used as a reliable method of determining the shear strength parameters of rock joints. Drainage of the ground and excavations. This activity is designed to illustrate an application of resistive forces in the introductory physics curriculum with an interdisciplinary twist.
All these problems should be well understood for rational planning of experiments. The second part of the book considers the applications of various theories which were either first developed for descriptive purposes in continuum mechanics and then adopted in soil and rock mechanics, or were specially developed for the latter discipline. The results prove the potential of the finite element approach for the assessment of the safety factor. In some of these cases the effectiveness is also established on the basis of a comparison with experimental data, from in situ monitored structures or small scale centrifuge tests. Lecture Notes in Applied and Computational Mechanics, vol 9. Numerical results obtained by strength reduction are compared with limit analysis upper bound solutions derived using a series of linear failure surfaces tangent to the actual non-linear failure surface. Chapter 6 is a natural expansion of the arguments put forward in the previous chapter.
Clay particles and ground water. Performances of underground twin caverns can be unsatisfactory as a result of either instability collapse or excessive displacements. This study simulated the ultimate and serviceability performances of underground twin rock caverns of various sizes and shapes. In addition, parameters are studied to investigate the stability factors as functions of the buried depth, roof span, roof salt thickness and roof salt Young's modulus, overlying non-salt thickness, overlying non-salt Young's modulus and gas pressure, etc. The resulting formulae are extremely simple and can be very useful to make comparisons with empirical methods and numerical analyses. Generally, the critical failure of non-linear material structure can be denoted by 3 criterions in the numerical simulations Dawson et al. The comparisons indicate that the maximum difference does not exceed 3.
Mechanical Models of Rocks and Soils. First, some heuristic considerations about the dynamics of experimental system are presented. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. The experimental results for all the materials tested were compared with the theoretical predictions obtained from the own theoretical model based on the methods of the damage mechanics. Experiments performed also showed that for certain configuration of properties of matrix materials and amount of steel fibers no effect of reinforcement was practically detected. But depending upon the assumptions on the inter-slice forces, the factor of safety resulting from the limit equilibrium method is not uniquely determined. The global factor of safety is used as the criterion for determining the ultimate limit state and the calculated maximum displacement around the cavern opening is adopted as the serviceability limit state criterion.