AEROGAS DYNAMIC REGULATIONS VENTILATION OF CONSTRUCTION TUNNELS

2020 ◽  
Vol 3 (1) ◽  
pp. 230-243
Author(s):  
A.N. KACHURIN ◽  
◽  
O.A. AFANASIEV ◽  
G.L. APETE ◽  
V.P. Stas ◽  
...  
Keyword(s):  
Rock Mass ◽  
Gas Exchange ◽  
Cross Section ◽  
Technical Problem ◽  
Dynamic Processes ◽  
Theoretical Studies ◽  
Large Cross Section ◽  
Gas Dynamic ◽  
Under Construction ◽  
Experimental And Theoretical Studies

The study of aerogasdynamics of long tunnels during the period of their construction is an urgent scientific and technical problem. On the basis of experimental and theoretical studies, the existing regularities of gas exchange of the rock mass with the atmosphere of the tunnels and the regularities of the air-gas-dynamic processes of the transfer of gas impurities to the atmosphere of tunnels of large cross-section were clarified, which made it possible to improve the methodology for calculating the amount of air and predicting gas situations for underground tunnels under construction.

PHYSICAL PREREQUISITES FOR GAS PERMEABILITY SIMULATION OF MINED ROCK MASS

2021 ◽  
pp. 78-84
Author(s):  
Oleksandr Shashenko ◽  
◽  
Vladyslava Cherednyk ◽  
Natalia Khoziaikina ◽  
Dmitro Shashenko ◽  
...  
Keyword(s):  
Rock Mass ◽  
Physical Model ◽  
Rock Sample ◽  
Coal Mass ◽  
Dynamic Processes ◽  
Deformation Diagram ◽  
Gas Dynamic ◽  
Laboratory Test Results ◽  
Deformation Properties ◽  
Complete Deformation

Purpose. Justification of the gas collectors formation physical model on the basis of research of conformity of permeability of rock mass to the full diagram of rock sample deformation. Methodology consists in sequential analysis of the stages of the complete deformation diagram of the rock specimen under “hard” loading, comparing them with the stages of formation of the high stress zone in front of the lava bottom and statistical analysis of laboratory test results. Results. Based on the rock’s deformation properties analysis and their comparison with the rock sample full deformation diagram, the physical model of formation of gas reservoirs during the development of gas-saturated coal seam is substantiated. Within the solved problem framework, four stages of the complete deformation process are analyzed, namely: elastic, at the limit of strength, out-of-bounds stage and equivoluminal flow zone. The gas collector boundaries, which are the characteristic points of the rock sample deformation diagram in specified deformations mode (the limit of elastic strength and the limit of final strength) are determined. It is proved that the structural and textural features of the coal mass in connection with the course of gas-dynamic processes are manifested in the change in the pores and cracks volume contained in it, which together make the filtration space. Knowledge regarding the transfer of the permeability changes established regularities and free methane accumulation zones formation to the real rock mass, if the process of its forgery is considered as a consistent change of geomechanical states of rocks, is obtained. Scientific novelty lies in the first substantiated possibility of modeling the stress state before the longwall face by equivalent stages of the rock sample destruction in the given deformations mode. Gradual comparative analysis of the internal mechanism of rock samples deformation along the complete deformation diagram allowed establishing causal relationships between geomechanical and gas-dynamic processes in coal mass, and qualitatively characterizing general trends in permeability and volumetric expansion in changes of these samples. Practical value of the work lies in the justification of the principle of construction of a digital geomechanical model for the detection of man-made gas collectors in a mined coal mass.

Experimental and theoretical studies of the photoionization cross section ofFe4+

2006 ◽  
Vol 73 (2) ◽  
Author(s):  
J. M. Bizau ◽  
C. Blancard ◽  
D. Cubaynes ◽  
F. Folkmann ◽  
D. Kilbane ◽  
...  
Keyword(s):  
Cross Section ◽  
Photoionization Cross Section ◽  
Theoretical Studies ◽  
Experimental And Theoretical Studies

scholarly journals Numerical Simulation and Analysis of the Three-Step Excavation of an Extra-Large Cross-Section and a Low Flat-Ratio Railway Tunnel

2021 ◽  
Author(s):  
Wenxing Huo ◽  
Xue Shifeng ◽  
Zongzhi Zhao ◽  
Zhiyu Gao ◽  
Mingyue Shao
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Cross Section ◽  
Axial Force ◽  
Side Wall ◽  
Vertical Deformation ◽  
Large Cross Section ◽  
Railway Tunnel ◽  
Geological Conditions ◽  
Deformation Section

Abstract The Xinbaishiyan tunnel in the reconstruction Chengdu-Kunming railway Ermeishan-Mipan section mainly runs through dolomite with dolomitic limestone, with an excavation area of 260 m2, a maximum span of 22.3 m, a maximum height of 14.4 m, a vector height of 7 m, and a rise-span ratio of 0.31. The tunnel has an extra-large cross-section and it is a low flat-ration railway tunnel. This paper mainly describes the the finite element analysis for this tunnel excavation that was used to guide the construction. Finite element software was used to model the tunnel according to the engineering geological conditions of the tunnel. These engineering geological conditions included the rock mass, system bolts, middle pipe shed, steel arch and shotcrete, grouting layer, second lining and so on. Nonlinear construction phase analysis was adopted. The results showed that the maximum vertical deformation of the tunnel vault and the middle of the invert was about 34 mm. The vertical deformation of the tunnel could be divided into an acceleration deformation section, linear deformation section, deceleration deformation section, and stable deformation section. The maximum horizontal deformation in the middle of the side wall was about 12.3 mm. Under the effect of the initial support, the equivalent stress of the side wall gradually increased with the excavation of the steps and the increase of the support structure. The axial force of the bolt in the middle of the side wall was larger than that in other places and the axial force of the middle pipe shed went along with the excavation of the tunnel in waves. The steel arch and the shotcrete had the maximum effective stress at the arch shoulder, which played the role of the deformation and pressure for the surrounding rock. During the construction, the length and height of the three-step method had to be set reasonably. The middle pipe shed and the system bolt supported the rock mass together. In the construction of the extra-large cross section and the flat tunnel, there was no need to set up temporary support, which was convenient for mechanical excavation.

MONITORING THE STABILITY OF VERTICAL SHAFT FOR POTASSIUM MINES

2020 ◽  
Vol 3 (1) ◽  
pp. 304-317
Author(s):  
N.M. KACHURIN ◽  
◽  
I.A. AFANASIEV ◽  
V.S. PESTRIKOVA ◽  
P.P. STAS ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Rock Mass ◽  
Strain State ◽  
Theoretical Studies ◽  
Vertical Shaft ◽  
Support Material ◽  
Safe Operation ◽  
Predictive Assessment ◽  
The Stability ◽  
Experimental And Theoretical Studies

As a result of experimental and theoretical studies, the regularities of the interaction of vertical shafts of potash mines with the rock mass were clarified, which allows predictive assessment of the consequences of violations of construction geotechnology projects and to develop effective measures to restore lining and ensure safe operation of shafts. At the same time, during the construction of vertical shafts, deviations from projects occur without modeling the possible consequences of such violations of projects. However, for a predictive assessment of the consequences of violations of construction geotechnology projects and the development of effective recommendations for the restoration and ensuring the safe operation of shafts, it is necessary to use a system of control and measuring monitoring of the support material, and mathematical modeling of its stress-strain state.

scholarly journals Experimental Study of Blasting Excavation for Large Cross-Section Tunnel in Horizontal Layered Rock Mass

2021 ◽  
Author(s):  
Jie Mei ◽  
Wanzhi Zhang ◽  
Bangshu Xu ◽  
Yongxue Zhu ◽  
Bingkun Wang
Keyword(s):  
Rock Mass ◽  
Cross Section ◽  
Surrounding Rock ◽  
Large Cross Section ◽  
Large Area ◽  
Layered Rock ◽  
Blasting Excavation ◽  
Tunnel Blasting ◽  
Layered Rock Mass ◽  
Upper Face

Abstract The drilling and blasting method is still the main method in mountain tunnel excavation. For large cross-section tunnel in horizontal layered rock mass, tunnel blasting often causes serious overbreak and underbreak. In this study, blasting excavation tests of tunnel upper face were conducted and failure mechanisms of surrounding rocks with weak beddings and joints were analyzed based on the Panlongshan tunnel. Then, the blasthole pattern, the cut mode, a variety of peripheral holes, the charge structure and the maximum single-hole charge were optimized. Compared with the failure characteristics, overbreak and underbreak, and deformations of surrounding rocks before and after optimization, the latter was better in tunnel contour forming and surrounding rock stability. The results show that after optimization, the large-area separation of vault rock mass is solved, the step-like overbreak of spandrel rock mass is reduced and the large-size rock blocks and underbreak are avoided. The maximum linear overbreak of vault, spandrel, and haunch surrounding rocks is decreased by 42.3%, 53.7% and 45.1%, respectively. The underbreak at the bottom of the upper face is reduced from -111.5 to - 16.5 cm. The average overbreak area is decreased by 61.1%. In addition, the displacements after optimization finally converge to the smaller values. The arch crown settlement and the horizontal convergence of haunch are reduced by about 21.6% and 18.3%, respectively. Furthermore, from the completion of blasting excavation to the stabilization of surrounding rock, it takes less time by using the optimized blasting scheme.

Control of gas-dynamic processes in floor rock mass in sylvinite bed AB of the Upper Kama Potassium Salt Deposit

2015 ◽  
pp. 89-92
Author(s):  
S. A. Andreiko ◽  
◽  
N. A. Litvinovskaya ◽  
T. A. Lyalina ◽  
◽  
...  
Keyword(s):  
Rock Mass ◽  
Potassium Salt ◽  
Dynamic Processes ◽  
Salt Deposit ◽  
Floor Rock ◽  
Gas Dynamic
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