There are the results of a study of the factors determining the formation and changes in the filtration properties of a heap leaching stack formed from pelletized poor sandy-clay ores. An analysis of methods of investigation of filtration properties of ore material for different stages of heap leaching plots functioning is carried out. Influence of segregation process during stack dumping on formation of zones with very different permeability parameters of ore has been established by experimental and filtration works. The construction and application of a numerical model of filtration processes in pelletized ores based on laboratory experiments is shown. By means of solution percolation simulation at different irrigation intensities the justification of optimal stack parameters is provided in terms of the geomechanical stability and prevention of solution level rise above the drainage layer.
A method for predicting the stress-strain state of the lining of underground structures, the shape of the cross-section of which is different from the circular outline, is considered. The main task of the study is to develop a methodology for assessing the influence of the parameters of the cross-section shape of underground structures on the stress state of the lining. To solve this problem, a method for calculating the stress state of the lining for arched tunnels with a reverse arch and quasi-rectangular forms is substantiated and developed. The methodology was tested, which showed that the accuracy of the prediction of the stress state of the lining is sufficient to perform practical calculations. An algorithm for multivariate analysis of the influence of the cross-sectional shape of underground structures of arched and quasi-rectangular shapes on the stress state of the lining is proposed. Parametric calculations were performed using the developed algorithm and regularities of the formation of the stress state of the lining of underground structures for various engineering and geological conditions, as well as the initial stress state field, were obtained. A quantitative assessment of the influence of geometric parameters of tunnels on their stress-strain state was performed.
The article assesses the impact of repeated blasts on the stress-strain state of the shotcreting support, which negatively affects the bearing capacity of the support and can lead to the formation of local rock falls in places of significant degradation of the shotcreting strength. Despite the fact that a single seismic load usually does not have a significant impact on the technical condition of the shotcreting support, repeated dynamic loading can lead to the development of negative processes and affect the safety. The article considers unreinforced and dispersed-reinforced shotcreting concrete as a shotcreting support. Models of deformation of rock and shotcreting support have been studied. To describe the deformation model of a rock mass, an elastic–plastic model based on the Hook-Brown plasticity condition has been accepted, which accurately describes the elastic-plastic behavior of a fractured medium. When performing the prediction of the stress-strain state of the shotcreting support, a model of plastic deformation of concrete with the accumulation of Concrete Damage Plasticity (CDP) was adopted, which allows to comprehensively consider the process of concrete deformation both under conditions of uniaxial compression and stress, and with minor edging draft. At the first calculation stage, a forecast of the seismic waves propagation in the immediate vicinity of the explosive initiation site was made. At the second stage, forecasts of the seismic waves propagation to the mine working and the stress-strain state of the support were made. On the basis of the performed studies, a methodology for assessing the impact of repeated blasts on the stress-strain state of the shotcreting support of the mine working is proposed.
The article proposes a method for predicting the stress-strain state of the vertical shaft lining in saliferous rocks at the drift landing section. The paper considers the development of geomechanical processes in the saliferous rock in the landing area, the support is viewed as a two-layer medium: the inner layer is concrete, the outer layer is compensation material. With this in view, the paper solves the problem of continuum mechanics in a spatial setting, taking into account the long-term deformation of salts and the compressibility of the compensation layer. Long-term deformation of saliferous rocks is described using the viscoplastic model of salt deformation into the numerical model, and the crushable foam model to simulate the deformation of the compensation layer. This approach considers all stages of the deformation of the compensation layer material and the development of long-term deformations of saliferous rocks, which makes it possible to increase the reliability of the forecast of the stress-strain state of the vertical shaft lining.
The relationship between displacements of the excavation contour and distance to the excavation face is obtained in the paper. The relationship allows to calculate support pressure with the account for delay of the support installation. Some calculation results of axial forces in the support are given. Calculations are made on the basis of finite-element method with three dimensional models.
Analysis of anisotropy behavior of clays based on the laboratory testing and publication is presented. Microstructural physical model of interaction between clay aggregates is proposed. Mathematical description of geomaterial based on the microstructural consideration which account for induce and inherent anisotropy is suggested.
The main reasons of soil deformation during deep excavation construction are presented. Numerical modeling of deep excavation construction with an account of support system is conducted. Conclusions on the application area of typical soils models is made.
In work the option of the multipurpose underground complex being part of the multystoried high-rise building is considered. The complex settles down in underground part of the building and carries out a base role, replacing with itself the usual plates-but-pile base. Predesigns by a method of final elements taking into account staging of construction of an underground complex and the land high-rise building are executed. Sizes and a picture of distribution of vertical displacements are received as a result of calculations.
Numerical model of lining yield element is created. Induced deformation Force – Displacement behavior of lining yiled elements with different geometrical sections is founded. Deformation state of lining element under induced displacement is presented.
Finite element analysis of tunnel construction in urban area is given. Soil material model parameters determination is considered. 3d finite element analysis of tunnel development is carried out. Variation of settlements and settlement troughs according to face and radial shield pressure and initial stress state are shown. Comparison of numerical modeling results and results of in-situ settlements measurement is done.
Contact stiffness between two particles is considered. Analysis of interaction between two particles based on the smooth and rough contact is done. Dependence of contact stiffness on normal forces and particles surface roughness is presented.
The intelligent technology of designing of the constructions of pillar underground station is adduced. Station is building with applying of low-settle technology, which takes into consideration main stages of the building process. The scheme of interaction of the system «support lining-soil massif» was accepted as basic scheme of calculations. The calculations of the stress-strain condition of constructions was performed with applying of finite-elements method.
Comparison of results of calculations of the tangential stresses on the inner contour of tunnel lining and radial stresses on the outer contour is done. Stresses are found by solving the problem of interaction in geomechanical system «lining-ground massif» in 2D and 3D model (single layer tunnel lining and double layer tunnel lining). Area of correct application of 2D models are revealed.
Analysis of tunnel induced settlement due to tunnel development with a help of TBM is given in current article. Surface settlement trough and settlement profile in longitudinal and transverse directions is shown below. A brief analysis of semi-empirical method of tunnel induced settlement calculation and determination of strains around excavation is given. Volume loss is given based on the in-situ observation.
Numerical modeling of cast iron lining stress and strain state of pylon deep underground station is done. Due to complex geometry of underground station, step by step excavation and lining installation numerical modeling was done in three dimensional space.
This article give a general overview of methods to solve large scale geotechnical problems, nonlinear high deformation and plastic problems, self contact of strata and application of high performance computing.
The results of in-situ measurements of vertical displacements of the tunnel lining of the St. Petersburg subway are presented. The 3d-model of interaction between soil and tunnel lining subjected to initial geostatic stress state is considered, and vertical displacements of the lining along the tunnel are used as an additional boundary condition. The calculated tangential stresses in the lining are compared with in-situ results of crack zone formation.
Classification of radioactive waste by the degree of its activity is given. Basic requirements to the construction site of radioactive waste repository or burial site are specified. Possible constructive solutions of underground repositories are briefly considered and a detailed description of the spiral structure of RAW repository is given. The influence of temperature and radiation on physical and mechanical properties of concrete and clay is estimated. The character of temperature field distribution around the underground RAW repository in time is obtained. The stress-strain state of the support was evaluated and loads on the support were found under the combined action of temperature and rock pressure, taking into account changes in the physical and mechanical properties of concrete and clay.
The problem of temperature stress distribution around underground radioactive waste storage facilities is formulated. Blue clays in the Northwest region of Russia were taken as geological formations. The problem is solved by the finite element method. The effect of the temperature factor on the stress-strain state of the "pillar-mass" system was found out. The character of surface rise as a function of temperature in the chamber has been established. The emergence of pronounced tensile zones in the massif caused by temperature stresses has been noted. The character of stress distribution σ x and σ y in the massif and tunnel lining has been analyzed.
The distribution of temperature and rock pressure stresses with regard to the temperature factor around underground radioactive waste (RAW) repositories in the underground space is considered. The geological formations taken are blue clays deposited in the Northwest region of Russia. The problem is solved by the finite element method. Influence of a temperature factor on the stress-strain state of the support-mass system was found out. The surface elevation from the temperature in the RAW chambers has been established. The analysis of the influence of the RAW chambers on each other has been made. The patterns of horizontal and vertical stresses distribution along the chamber axis were found.