The Selection and Application of Filling Material Based on Long-Term Strength of Backfill Body

2011 ◽  
Vol 239-242 ◽  
pp. 3156-3160
Author(s):  
Bao Jie Fu ◽  
Min Tu
Keyword(s):  
High Stress ◽  
Filling Material ◽  
Term Strength ◽  
Exponential Relationship ◽  
Rock Body ◽  
Deep Mine ◽  
Long Term Stability ◽  
Working Face ◽  
Support Resistance

High stress makes backfill body present the rheological properties in deep mine. This paper first uses RRTS-ⅢA to carry on creep test of specimen in different proportion, according to ε-t curves under different load levels to determine the specimen’s long-term strength, based on the exponential relationship of rock block and rock body, the long-term compressive strength is derived, combining with concrete parameters of working face, mixture ratios of filling material which meet long-term stability are selected, while analyzing the support resistance of backfill body. The results show that this design can effectively avoid the rheological instability of backfill body.

DYNA Numerical Experiment on Long-Term Stability of Strip Pillar in Deep Mine

2011 ◽  
Vol 217-218 ◽  
pp. 1520-1524
Author(s):  
Chun Qiu Wang ◽  
Shi Bin Gu ◽  
Zhong Ju Wei ◽  
Bo Li ◽  
Shao Jie Chen
Keyword(s):  
Stable State ◽  
Support Effect ◽  
Test Results ◽  
Deep Mine ◽  
Long Term Stability ◽  
Creep Stress ◽  
Working Face ◽  
Stress And Deformation ◽  
Overlying Strata

The creep test of the No. 3 coal seam of Daizhuang Coal Mine is carried. Based on the experiment results, the creep support effect of deep pillar is analyzed with LS-DYNA. The results show that the circumferential initial creep stress of the tested coal is 3.061MPa and the circumferential initial creep stress is far below the axial initial creep stress which is 7.020MPa. In addition, the creep strength is 9.3266MPa and the creep coefficient is 0.6472. According to the test results, the creep support effect of deep strip pillar can be simulated excellently with LS-DYNA. Stress and deformation in simulated strip pillar show evident rheology. Many changes will take place in the stable situation of pillar after the working face mining. Under the effect of the overlying strata, this pillar turns into steady creep state after 15~16 months, then the pillar is able to maintain long-term stable state.

scholarly journals Study and Application of Roof Cutting Pressure Releasing Technology in Retracement Channel Roof of Halagou 12201 Working Face

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Ma Xingen ◽  
He Manchao ◽  
Wang Yajun ◽  
Zhang Yong ◽  
Zhang Jiabin ◽  
...  
Keyword(s):  
High Stress ◽  
Hydraulic Support ◽  
Working Face ◽  
Geological Conditions ◽  
Support Resistance ◽  
Cutting Effect ◽  
Mining Pressure ◽  
Cutting Height ◽  
First Time ◽  
Roof Deformation

The retracement channel roof cutting (RCRC) technology can change the overburden structure actively by cutting off the roof of channel along the direction of working face tendency and make use of the gangue collapsing from roof cutting range to fill the goaf and weaken the mining pressure during the retracement process of working face. In order to solve the problems of high stress in surrounding rock and serious deformation of retracement channel in Halagou coal mine, it is the first time that the pressure releasing test is carried out on the 12201 working face by the method of the directional presplitting roof cutting in retracement channel. First, according to statics theory and energy theory, the stress state of hydraulic support and roof deformation mechanism of retracement channel are analyzed. Then the roof cutting design of retracement channel is determined according to the geological conditions of 12201 working face, and the cutting effect is analyzed by numerical simulation. Finally, the field test is carried out on the 12201 working face to verify the effect of pressure releasing by roof cutting. The result shows that, with the roof cutting design including the roof cutting height being 8m and roof cutting angle being 45°, the roof subsidence of the 12201 working face retracement channel in Halagou mine is reduced to 132.5mm, and the hydraulic support resistance is maintained at 1361KN. And there is no hydraulic support crushed; the deformation of the retracement channel is also small; namely, the effect of roof cutting for pressure releasing is obvious.

scholarly journals Gob-Side Entry Retaining Involving Bag Filling Material for Support Wall Construction

2020 ◽  
Vol 12 (16) ◽  
pp. 6353
Author(s):  
Zhaowen Du ◽  
Shaojie Chen ◽  
Junbiao Ma ◽  
Zhongping Guo ◽  
Dawei Yin
Keyword(s):  
Field Tests ◽  
Filling Material ◽  
Construction Technology ◽  
Working Face ◽  
Support Resistance ◽  
Pillar Mining ◽  
High Production ◽  
Wall Construction ◽  
Thin Seam ◽  
Seam Mining

Gob-side entry retaining, also termed as non-pillar mining, plays an important role in saving coal resources, high production and efficiency, extending the service life of mine and improving the investment benefit. Herein, a gob-side entry retaining method involving the use of bag filling material for wall construction is proposed based on the thin seam mining characteristics. First, a gob-side entry retaining mechanical model is established, and the side support resistance of the 8101 working face is calculated. The mechanical properties of the bag material are investigated through experiments, and the construction technology of the gob-side entry retaining approach involving the use of bag filling material for wall construction is introduced. The deformation on the two sides, the roof and floor of the roadway, are simulated via numerical methods and monitored during field tests. The results show a small control range for the deformations and a good roadway retention effect, thereby proving the feasibility of the bag filling material for wall construction. This study provides a reference for the development of gob-side entry retaining mining for thin coal seams.

scholarly journals Evaluating Long-Term Strength and Time to Failure of Sandstone with Different Initial Damage

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Rongbin Hou ◽  
Yanke Shi ◽  
Leige Xu ◽  
Jinwei Fu ◽  
Kai Zhang
Keyword(s):  
Failure Time ◽  
Term Strength ◽  
Steady Creep ◽  
Creep Failure ◽  
Damage State ◽  
Term Stability ◽  
Long Term Stability ◽  
Creep Stress ◽  
Initial Damage

Long-term strength (LTS) of rock materials is important for the long-term stability analysis and the failure prediction of structures in rock engineering. Numerous studies have been carried out on the LTS for various kinds of rock; however, the effects of initial damage on the LTS and creep failure time of rock have not been conducted. In the present study, the creep experiment with controllable initial damage state of rock was designed. Then, the LTS of rock specimens with different initial damage was determined by four methods (i.e., the isochronous stress-strain curve method, the steady creep discriminated method, the volumetric strain inflexion point determined method, and the intersection of the steady creep rate method). The results show that, with the increase in the initial damage, the LTS of rock decreases and the relationship between the initial damage and the LTS of rock can be described as a linear function. Finally, an evaluation method for predicting the creep failure time of rock under a single stress level was proposed. In addition, the creep failure time of rock with different initial damage under different creep stress levels was obtained by the method. The results indicate that both the initial damage and the creep stress levels have a great influence on creep failure time, i.e., greater initial damage or creep stress leads to a shorter period for rock failure. Thus, for analyzing the long-term stability of rock mass structure, not only the influence of in situ stress but also the initial damage state of the surrounding rock should be considered.

Numerical Simulation Study on Setting Stopping Line of Working Face in Shuguang Mine

2014 ◽  
Vol 580-583 ◽  
pp. 2554-2557
Author(s):  
Hua Jun Xue ◽  
Jun Chen ◽  
Bo Liu ◽  
Jie Kong ◽  
Zhi Jun Hao
Keyword(s):  
Numerical Simulation ◽  
Recovery Rate ◽  
Coal Pillar ◽  
Economic Benefits ◽  
Surrounding Rock ◽  
Long Term Stability ◽  
Rock Stability ◽  
Working Face ◽  
Stopping Line

The surrounding rock deformation of pedestrian roadway was serious under the influence of the working face. And it has affected the safety and normal use of roadway. To ensure the long-term stability of the pedestrian roadway surrounding rock and increase the coal recovery rate of working face, the paper studied the position of stopping line of 1203 working face by numerical simulation. The results show that setting 115m wide of security coal pillar between 1203 working face and pedestrian roadway that the area of stress concentration near the working face has less effect on the pedestrian roadway could better control the surrounding rock stability of the pedestrian roadway and meet the need of the long-term normal production use. It narrows the width of security coal pillar, increase the coal resources recovery rate and achieve the better economic benefits.

scholarly journals Research on Reasonable Width of Coal Pillars of Non-equal Width Isolated Working Face Heading Goaf in Deep Mine

2021 ◽  
Author(s):  
weili yang ◽  
Quande wei ◽  
Zhonghui Wang ◽  
Zhizeng Zhang ◽  
Xiaocheng Qu ◽  
...  
Keyword(s):  
Rock Burst ◽  
Critical State ◽  
Research Result ◽  
High Stress ◽  
Coal Pillar ◽  
Stress Monitoring ◽  
Equilibrium Relation ◽  
Deep Mine ◽  
Working Face ◽  
Coal Pillars

Abstract Setting reasonable coal pillar is a key to ensure safe mining of island coal face heading goaf in deep mine. With determination of reasonable width of coal pillars of non-equal width isolated working face 3201 in worked-out area in one mine in Shandong as the engineering background, a research was conducted on the mechanism of rock burst induced by and the reasonable width of coal pillars of isolated working face in worked-out area and the main conclusions are as follows: (1) the coal pillars of isolated working face 3201 in worked-out area changed from pillars with goaf on two sides→pillars with goaf on three sides→pillars with goaf on four sides, resulting in evolution of overlying strata from pre-mining static “┒-shaped” structure→“C-shaped” structure→“O-shaped” structure and corresponding spatial stress from “saddle-shaped” profile→“platform-shaped” profile→“arch-shaped” profile; (2) the rock burst was induced by coal pillars, because the high stress on coal pillars at critical state of a rock burst was greater than their comprehensive strength and induced a rock burst due to sudden instability; (3) by establishing a bearing and load model of coal pillars at critical state of a rock burst and based on the equilibrium relation, an method for estimating reasonable width of coal pillars of isolated working face in worked-out area in deep mine was derived and applied to the isolated working face 3201 in worked-out area, thus comprehensively determining that the width of coal pillars should be 130m. The field stress monitoring verified the reasonability. The research result is of great significance to prevention of rock burst induced by coal pillars of isolated working face in worked-out area in deep mine.

scholarly journals Investigation on Failure Characteristics of Coal Seam Floor in Paste Filling Working Face

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Qingliang Chang ◽  
Xingjie Yao ◽  
Chongliang Yuan ◽  
Qiang Leng ◽  
Hao Wu
Keyword(s):  
Theoretical Model ◽  
Coal Seam ◽  
Water Inrush ◽  
Failure Behavior ◽  
Term Strength ◽  
Failure Characteristics ◽  
Working Face ◽  
Floor Failure ◽  
Failure Depth

Water inrush disasters are extremely prone to occur if the coal seam floor contains a confined aquifer. To find out the failure behavior of coal seam floor of paste filling working face, a beam-based theoretical model for the floor aquifuge was built, and then, the water inrush risk was evaluated based on the thickness of floor aquifuge. Next, the floor failure characteristics of the paste filling face was numerically studied and the effects of the filling interval and long-term strength of the filling body on the floor failure depth, stress and displacement distributions, and plastic zone were explored. The results showed that the theoretical model for evaluating the safety of the floor of the paste filling face based on the empty roof distance is proved to be consistent with that of the empirical formula judged based on the assumption that the paste filling working face was regarded as a cut hole with a certain width. The filling interval has a significant effect on the stress concentration of the surrounding rock, failure depth of floor, and roof-floor convergence. The smaller the filling interval is, the smaller their values are. When the filling rate is 98%, the long-term strength of the filling body is 5 MPa, and the floor failure depth is not more than 4 m. In contrast, the strength of the filling body has no obvious influence on the floor failure depth, but it has a certain impact on the roof-floor convergence. From the perspective of reducing floor failure depth, there is no need to increase the long-term strength of backfill, but it is necessary to increase the early strength of backfill so as to reduce the width of the equivalent roadway.

scholarly journals CRITERIAL METHOD OF CALCULATIONS OF LONG-TERM STABILITY OF THE BOREHOLE

2018 ◽  
pp. 79-84
Author(s):  
O. A. Shipilova ◽  
S. V. Shafieva
Keyword(s):  
Strength Criterion ◽  
Oil Wells ◽  
Term Strength ◽  
Short Term ◽  
Term Stability ◽  
Long Term Stability ◽  
Short Term Strength

The article examines the possibility of applying the Mohr - Coulomb short-term strength criterion to the calculations of long-term stability of open oil wells. The results of calculation of long-term and short-term strength on the basis of the polygon of stability are analyzed.

Methylene unit calibration for analysis of organic acids by gas--liquid chromatography/mass spectrometry.

1982 ◽  
Vol 28 (2) ◽  
pp. 349-351
Author(s):  
I L Bromberg ◽  
J A Heininger ◽  
A G Cherian
Keyword(s):  
Reference Standards ◽  
Gas Liquid Chromatography ◽  
Good Precision ◽  
Exponential Relationship ◽  
Long Term Stability ◽  
Methylene Unit ◽  
Mass Spectrometer System ◽  
Computer Controlled ◽  
Spectrometer System

Abstract We describe a method for automatic computation of "methylene unit" retention-time indices in real time on a computer-controlled gas chromatograph/mass spectrometer system. The calculation is based on the exponential relationship between the methylene unit values of hydrocarbon reference standards and the oven temperature at their elution. Using this mathematical relationship, we calculated calibration factors, which eliminates the need to include a set of methylene unit reference standards with each run and simplifies and speeds identification of unknown peaks in chromatograms. Long-term stability and good precision of the calibration factors were observed during the six-month period of study.

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