Study on Surrounding Rock Pre-Stressed Crossed Anchor Control Technology in Roadway with Large Mining Depth

2012 ◽  
Vol 524-527 ◽  
pp. 471-475
Author(s):  
Xi Gui Zheng ◽  
Qin Jian Zhan ◽  
Bin Wang
Keyword(s):  
Rock Mass ◽  
Stress Distribution ◽  
Triaxial Compression ◽  
Soft Rock ◽  
High Strength ◽  
Wall Rock ◽  
Difficult Problem ◽  
Mining Depth ◽  
Rock Creep ◽  
Drainage Pipe

Based on the deep soft rock creep mechanism, according to the physical characteristics of bauxitic mudstone in ingate at the level of -1015 m of Kong Zhuang colliery, we solved the technical difficult problem of choosing anchor points of soft rock supporting roadway in ingate. Using high strength and low relaxation steel strand to reinforce by crossed anchor, in combination with the depth hole grouting technology, improve pressure-bearing capacity of wall rock in the ingate, safe passage and drainage pipe area. We analyze the stress distribution characteristics of rock mass, contrasting on the stress distribution at the end of partially grouted bolt and the rock mass. Practice shows that crossed anchor rock mass has triaxial compression over all, the bunch body has a single structure, and it is easily to be analyzed. We not only control the roof settling in the area of ingate is, but also solve the floor heave problem in safe passage and drainage pipe area.

The Studying of Reinforcement Mechanism of Fully Grouting Rock Bolt in Brittle Wall Rock Mass

2013 ◽  
Vol 690-693 ◽  
pp. 786-792
Author(s):  
Xun Guo Zhu
Keyword(s):  
Rock Mass ◽  
Stress Distribution ◽  
Axial Force ◽  
Load Transfer ◽  
Wall Rock ◽  
Displacement Function ◽  
Rock Bolt ◽  
Radial Deformation ◽  
Tunnel Wall ◽  
Dilatancy Angle

The bolt’s load transfer differential equation has established according the stress equilibrium in a small section of a bolt and load transfer mechanics. And according the rock mass deformation before and after bolt assembling, the rock bolt’s load transfer equation has gained. In this paper, from later researching achievement, the radial displacement function of brittle wall rock for tunnel is gotten. And combining the radial deformation of tunnel wall rock mass, the axial force and friction resistance of rock bolt have gotten in brittle wall rock mass. Through analyzing the stress distribution feature and stress distribution tendency and affection factors, the affection factors to anchoring results is the dilatancy angle. And through the studying, it is show that the axial force and shear stress of rock bolt are bigger with the dilatancy angle increase

scholarly journals Effect of geological and technological parameters on the convergence in a stope

2021 ◽  
pp. 16-22
Author(s):  
S.F Vlasov ◽  
Ye.V Moldavanov
Keyword(s):  
Rock Mass ◽  
Numerical Experiments ◽  
Computer Modelling ◽  
Main Roof ◽  
Wall Rock ◽  
Extraction Column ◽  
Technological Parameters ◽  
Mining Depth ◽  
Powered Support ◽  
Solid Works

Purpose. To study regularities in changes in convergence of wall rocks along a setting line of the powered props depending upon the sandstone availability within the roof, mining depth, as well as its position relative to the coal seam along the length of the extraction column based on the results of numerical experiments and forecast probable zones of rigid settlement of the powered support units according to a longwall length at any moment of a stope arrangement along the extraction pillar in accordance with changes in geological and technological parameters. Methodology. The paper represents numerical experiments based upon 3D computer modelling of incremental stope advance within a layered transverse and isotopic rock mass while applying Solid Works Simulation 2019 software. Findings. The research results, concerning the nature of wall rock distribution value within a stope, are given. The results were obtained using incremental computer modelling of the longwall advance within a layered transverse and isotopic rock mass within the area of initial caving of the main roof. Originality. In the context of the Western Donbas mines, regularities of convergence value of wall rock distribution have been determined depending upon certain changes in such a system of geological and technological parameters as: availability of sandstone with 5 and 30 m thickness both within the immediate rock and at 30 m distance as well as nonavailability of sandstone within a roof; 215, 260 and 305 m changes in longwall length; 150, 300 and 450 m changes within a zone of initial caving of the main roof (1545 m) with 10 m increment of longwall distancing from an installation chamber at 1050 m distances. Practical value. The identified regularities of changes in convergence value make it possible to forecast probable zones of rigid settlement of the powered support units depending upon the longwall length at any moment of a stope location along the extraction pillar irrespective of mining depth. The abovementioned helps optimize the parameters of seam extraction for the conditions of the Western Donbas mines if required.

Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

2020 ◽  
pp. 67-75
Author(s):  
Van Min Nguyen ◽  
V. A. Eremenko ◽  
M. A. Sukhorukova ◽  
S. S. Shermatova
Keyword(s):  
Rock Mass ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rock Fracture ◽  
Strain Analysis ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Secondary Stress ◽  
Principal Stresses ◽  
Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

scholarly journals Stress and deformation analysis of gob-side pre-backfill driving procedure of longwall mining: a case study

2021 ◽  
Author(s):  
Rui Wu ◽  
Penghui Zhang ◽  
Pinnaduwa H. S. W. Kulatilake ◽  
Hao Luo ◽  
Qingyuan He
Keyword(s):  
Rock Mass ◽  
Stress Distribution ◽  
Coal Seam ◽  
Abutment Pressure ◽  
Longwall Mining ◽  
Vertical Stress ◽  
Floor Level ◽  
Working Face ◽  
Floor Heave ◽  
Stress And Deformation

AbstractAt present, non-pillar entry protection in longwall mining is mainly achieved through either the gob-side entry retaining (GER) procedure or the gob-side entry driving (GED) procedure. The GER procedure leads to difficulties in maintaining the roadway in mining both the previous and current panels. A narrow coal pillar about 5–7 m must be left in the GED procedure; therefore, it causes permanent loss of some coal. The gob-side pre-backfill driving (GPD) procedure effectively removes the wasting of coal resources that exists in the GED procedure and finds an alternative way to handle the roadway maintenance problem that exists in the GER procedure. The FLAC3D software was used to numerically investigate the stress and deformation distributions and failure of the rock mass surrounding the previous and current panel roadways during each stage of the GPD procedure which requires "twice excavation and mining". The results show that the stress distribution is slightly asymmetric around the previous panel roadway after the “primary excavation”. The stronger and stiffer backfill compared to the coal turned out to be the main bearing body of the previous panel roadway during the "primary mining". The highest vertical stresses of 32.6 and 23.1 MPa, compared to the in-situ stress of 10.5 MPa, appeared in the backfill wall and coal seam, respectively. After the "primary mining", the peak vertical stress under the coal seam at the floor level was slightly higher (18.1 MPa) than that under the backfill (17.8 MPa). After the "secondary excavation", the peak vertical stress under the coal seam at the floor level was slightly lower (18.7 MPa) than that under the backfill (19.8 MPa); the maximum floor heave and maximum roof sag of the current panel roadway were 252.9 and 322.1 mm, respectively. During the "secondary mining", the stress distribution in the rock mass surrounding the current panel roadway was mainly affected by the superposition of the front abutment pressure from the current panel and the side abutment pressure from the previous panel. The floor heave of the current panel roadway reached a maximum of 321.8 mm at 5 m ahead of the working face; the roof sag increased to 828.4 mm at the working face. The peak abutment pressure appeared alternately in the backfill and the coal seam during the whole procedure of "twice excavation and mining" of the GPD procedure. The backfill provided strong bearing capacity during all stages of the GPD procedure and exhibited reliable support for the roadway. The results provide scientific insight for engineering practice of the GPD procedure.

scholarly journals Study on the Deformation Mechanism of Soft Rock Roadway under Blasting Disturbance in Baoguo Iron Mine

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Hong-di Jing ◽  
Yuan-hui Li ◽  
Kun-meng Li
Keyword(s):  
Rock Mass ◽  
Deformation Mechanism ◽  
Soft Rock ◽  
Deformation Monitoring ◽  
Underground Mines ◽  
Blasting Vibration ◽  
Iron Mine ◽  
The Stability ◽  
Soft Rock Roadway ◽  
Rock Roadway

In order to study the deformation mechanism of soft rock roadway in underground mines, it is necessary not only to study the influence of the dynamic disturbance caused by the cyclic mining blasting vibration on the stability of the soft rock roadway but also to study the degradation of the roadway surrounding rock itself and other factors. The paper presented a synthetic research system to investigate the factors that influence roadway rock structure deterioration in Baoguo Iron Mine. Firstly, the stability of rock mass was analyzed from the perspective of the physical and structural characteristics of the rock mass. Afterwards, according to monitoring data of mining blasting vibration, a suitable safety blasting prediction model for Baoguo Iron Mine was determined. And then, combining the results of mining blasting vibration monitoring and deformation monitoring, the effect of cyclic mining blasting on the stability of the soft rock roadway was obtained. By systematically studying the intrinsic factors of rock quality degradation and external environmental disturbances and their interactions, this paper comprehensively explores the deformation mechanism of soft rock roadway and provides the support for fundamentally solving the large deformation problems of soft rock roadway in underground mines.

Estimation of rockburst wall-rock velocity invoked by slab flexure sources in deep tunnels

2014 ◽  
Vol 51 (5) ◽  
pp. 520-539 ◽  
Author(s):  
Shili Qiu ◽  
Xiating Feng ◽  
Chuanqing Zhang ◽  
Tianbing Xiang
Keyword(s):  
Rock Mass ◽  
Seismic Source ◽  
Friction Angle ◽  
Wall Rock ◽  
Assessment Method ◽  
Source Mechanism ◽  
Uniaxial Tensile ◽  
Roughness Coefficient ◽  
Support Design ◽  
True Triaxial

For rock support in burst-prone ground, the wall-rock velocity adjacent to the surface of underground openings is a vital support design parameter, and depends on the seismic source mechanism inducing rockburst damage. In this study, to estimate the wall-rock velocity evoked only by rock slab buckling (an important rockburst source mechanism), a comprehensive velocity assessment method is proposed, using an excellent slab column buckling model with a small eccentricity, which relies on a novel compressive or tensile buckling failure criterion of rock slab. The true-triaxial loading–unloading tests and rockburst case analyses reveal that rock mass slabbing induced by high rock stress has major impacts on the evolution and formation of buckling rockburst in deep tunnels. Using a method based on the energy balance principle, the slabbing thickness of intact rock mass is also calculated by an analytical method, which indicates that the slabbing thickness parameter has a nonlinear relation to the following six parameters: uniaxial tensile strength (UTS), uniaxial compressive strength (UCS), normal stress (σn), length of joint (L), friction angle ([Formula: see text]), and joint roughness coefficient (JRC). These proposed models and methods have been quite successfully applied to rockburst and slabbing cases occurring in deep tunnels. These applications show that slab flexure is an important source mechanism invoking high wall-rock velocities and leading to severe rockburst damages in the area surrounding deep tunnels.

High Strength Combined Support Technology in Deep High Stress Soft Rock Roadway

2012 ◽  
Vol 524-527 ◽  
pp. 598-603
Author(s):  
Nian Jie Ma ◽  
Zhi Qiang Zhao ◽  
Hua Zhao ◽  
Li Shuai Jiang
Keyword(s):  
High Stress ◽  
Soft Rock ◽  
High Strength ◽  
Parameter Determination ◽  
Test Results ◽  
Actual Measurement ◽  
Computer Numerical Simulation ◽  
Soft Rock Roadway ◽  
Rock Roadway

In order to solve the serious damage and repeat revision problem of high stress soft rock roadway in deep -950 level of Tangshan coal mine, based on the theory of the maximum stress level, together with the actual measurement of geostress and the laboratory mechanical parameters of rock-core and computer numerical simulation, the high strength combined support technology and supporting parameters are determined and the engineering test has been done. The engineering test results show that the parameter determination of high strength combined support technology, which based on the actual measurement of geostress, can effective solve the support issue of high stress soft rock roadway and provide useful experience for similar engineering problems.

scholarly journals THE EFFICIENCY TEST OF A NEW TRENCH EXCAVATOR FOR SOFT ROCK MASS BY USE OF A SPEED CONTROL TYPE EDGE EXCAVATION SYSTEM

2006 ◽  
Vol 62 (2) ◽  
pp. 296-311
Author(s):  
Tatsuro MURO ◽  
Takahisa SHIGEMATSU ◽  
Koichi KOHNO ◽  
Yoichi SAKUHARA
Keyword(s):  
Rock Mass ◽  
Soft Rock ◽  
Speed Control ◽  
Efficiency Test
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