Rock mass elastic model and its application in mechanics of underground structures

2021 ◽  
pp. 133-139
Author(s):  
N.S. Bulychev ◽  
I.V. Goncharov ◽  
I.I. Savin
2021 ◽  
Vol 1 ◽  
pp. 17-24
Author(s):  
Abdessattar LAMAMRA ◽  
◽  
Dmitriy Leonidovich NEGURITSA ◽  
Samir BEDR ◽  
Ariant A. REKA ◽  
...  

Reserch relaevance. Most ground movements are generally due to rock instability, this natural phenomenon poses a risk to humanity. The properties of the rock mass directly influence the type of movement especially in underground structures. Research aim. Our goal is to characterize and classify the rock mass of diatomite from the sig mine using geomechanical classification systems such as the RQD and RMR in order to determine the quality of the rocks in the sig mine Western Algeria from the determination of the physical and mechanical properties. Methodology. In this article, the characterization analysis of the diatomite rock mass of the sig mine was carried out. First, determinations of the physical properties and carried out the triaxial test to determine the mechanical properties (young’s modulus, the friction angle, the dilatancy angle, the cohesion, the poisson’s ratio). Secondly to classify the deposit and give a recommendation to avoid stability problems. Research results. The results from physical and mechanical analyzes, it can be said that the nature of the rock present in the diatomite (underground mine) does not have enough resistance. Conclusion. Our study definitively proves that the rock mass of sig diatomite is of very low quality and it will be very dangerous for the underground mining work of the mine especially in places where the mineralized layer is very deep. And we suggest to replace the mining technique room and pillar currently used in the diatomite mine and put another mining method which includes roof support system to ensure the safety both of the miners and the equipment.


Author(s):  
M.A. Sonnov ◽  
A.V. Trofimov ◽  
A.E. Rumyantsev ◽  
S.V. Shpilev

The study is exemplified by complex workings of a main ore pass that include a variety of underground structures, usually with unique dimensions which depend on the function and size of the equipment placed. The technical solutions for the underground crushing plant and associated structures envisage construction of chambers with the height of up to 35 m and the width of up to 20 m at the depths exceeding 800-1000 m. Such conditions call for a closer attention to be paid to the mine support parameters, especially the bolting depth. A block geomechanical model was designed in the Micromine Mining Software for the rock mass of the new main ore pass. Geotechnical boreholes logs and results of physical and mechanical rock tests were used as the input data for the model. Four domains were identified in the block geomechanical model for subsequent numerical modelling. A 3D model of the stress-and-strain state of the rock mass was made using the CAE Fidesys software based on the Micromine wire-frame model of the main ore pass. The history of the rock mass incremental loading was reconstructed for correct simulation of its stress-and-strain state. Prior to the excavation, the rock mass is pre-stressed by the weight of the rock strata. The excavation phase was then simulated in the stepwise manner. An array of points with the values of maximum principal stresses was downloaded from the numerical model post-processing program and interpolated into the block geomechanical model to refine the SRF parameter of the Barton's Q rating. Based on the obtained Q values, the mine support parameters for chambers were determined using the Barton, Hutchinson and Potvin empirical methods.


2019 ◽  
Vol 56 (7) ◽  
pp. 970-982 ◽  
Author(s):  
Nuno Cristelo ◽  
Carlos Félix ◽  
Joaquim Figueiras

It is now accepted that current expeditious models for determining earth pressures on flexible underground structures under compacted layers do not include several technical nuances of the soil–structure interaction. Thus, these models are not capable of delivering an optimized design. The present paper compares the results from the well-known American Association of State Highway and Transportation Officials (AASHTO) model with two different numerical models — a user-friendly elastic model and a more robust finite element model — and with results retrieved from a full-scale monitoring of a concrete box culvert, 5.5 m high and 3.77 m width, over which a 15 m high embankment was built. This structure was instrumented selectively, over a period of almost 1 year, during which several parameters were recorded, including earth pressures and structural deformation. Results have shown that the two most significant drawbacks associated with the use of the AASHTO model are the inadequate evaluation of vertical pressure on the top slab and the coefficient of earth pressure, which results in a significant overestimation of the lateral pressures and, consequently, in an overall inefficient design of the structure.


1990 ◽  
Vol 112 (1) ◽  
pp. 62-68
Author(s):  
M. G. Karfakis

The in-situ deformability of rocks and the state-of-stress must be known for the analysis and design of surface and underground structures. This paper presents a method for determining the in-situ deformability of rock-masses using friction gages. Friction gages utilize the friction between the gage and the rock surface for detecting the strain changes. The method involves impressing friction gages on two opposite quadrants of the borehole wall, then radially loading the other two quadrants over 45-deg contact with a self-equilibrating pair of forces of sufficient magnitude to initiate and propagate tensile fractures. While loading, the friction gages detect the tangential strains on the borehole wall before, during and after fracturing of the rock. From the linear portion of the tangential stress-strain data, the elastic properties of the rock can be determined using the appropriate relationships. Furthermore, from the failure and post-failure portions of the tangential stress-strain data the tensile strength of the rock-mass and the in-situ state-of-stress can also be estimated. The theoretical basis of the method, and the fabrication, calibration and testing of the friction gage system, are described. Furthermore, practical field applications of the method are given.


2010 ◽  
Vol 43 (6) ◽  
pp. 857-875 ◽  
Author(s):  
Ömer Aydan ◽  
Yoshimi Ohta ◽  
Melih Geniş ◽  
Naohiko Tokashiki ◽  
K. Ohkubo

2017 ◽  
Vol 13 (1) ◽  
pp. 21-31
Author(s):  
Adrian Popovici ◽  
Cornel Ilinca ◽  
Cristian Anghel

Abstract The sectional stresses (M, N) in a gallery lining are computed comparatively numerical by FEM taking into account the interaction underground structure - surrounding ground and analytical by Protodiakonov method. The last method is based on coincidence arch born in ground over gallery. Comprehensive analyses allow to settle the domain in which Protodiakonov method can be applied as well as the conditions in which discharge arches appear in ground above underground or embedded structures. The study is available for galleries (tunnels) built so that their lining takes loads from undeformed ground (rock) mass surrounding gallery, existent before excavation.


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