scholarly journals 3D Numerical Modelling of the Application of Cemented Paste Backfill on Displacements around Strip Excavations

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7750
Author(s):  
Krzysztof Skrzypkowski
Keyword(s):  
Numerical Modeling ◽  
Cement Content ◽  
Cemented Paste Backfill ◽  
Mining Method ◽  
3D Numerical Modeling ◽  
Compressibility Coefficient ◽  
3D Numerical Modelling ◽  
Paste Backfill ◽  
First Time ◽  
Cylindrical Samples

This article presents laboratory and spatial numerical modeling of cemented paste backfill. The first part of the research concerned laboratory tests of a mixture of sand, water, and variable cement content (5%, 10%, and 15%). The density and curing time of the mixture were determined. Moreover, cylindrical samples with a diameter of 46 mm and a height of 92 mm were constructed, for which compressive and tensile strength were calculated after one, two, three, and four weeks. The second part of the research concerned 3D numerical modeling with the use of RS3 software. For the exploitation field with dimensions of 65 m × 65 m, a strip-mining method was designed. The main objective of the research was to determine the changes in displacements around the haulage room and transportation roadway located in the immediate vicinity of the exploitation field. For the first time in numerical modeling, a two-sided strip method was used for the four stages of mining the ore deposit where the post-mining space was filled with a cemented paste backfill. Based on this research, the compressibility coefficient was determined.

scholarly journals Investigating the Effect of Solid Components on Yield Stress for Cemented Paste Backfill via Uniform Design

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yong Wang ◽  
Aixiang Wu ◽  
Lianfu Zhang ◽  
Fei Jin ◽  
Xiaohui Liu
Keyword(s):  
Yield Stress ◽  
Mass Fraction ◽  
Cement Content ◽  
Uniform Design ◽  
Free Water ◽  
Experimental Program ◽  
Cemented Paste Backfill ◽  
Free Water Content ◽  
Key Factor ◽  
Paste Backfill

Cemented paste backfill (CPB) technology has been applied quite popular around the world. Yield stress is a key factor determining whether CPB could be transported. In order to reveal the effect of solid components on yield stress of CPB, a uniform design experimental program (four factors and six levels) was conducted to test the rheological property of a mine’s CPB. The tested four factors including mass fraction, cement versus other solids ratio, coarse tailings, and gravel contents were considered during the experiment design. Likewise, six experimental levels were given to each factor. Results of the test show that yield stress increased with the mass fraction and cement content. However, the trend reversed for the content of coarse tailings and gravel. Contribution of the four factors to yield stress in descending order is mass fraction > content of gravel > content of coarse tailings > cement versus other tailings ration. Effect of solid components on the yield stress of CPB is mainly due to the different flocculation structure inside the CPB. These various flow structures result in the different free-water content of CPB, leading to a different yield stress value.

Investigation of some controllable factors that impact the stress state in cemented paste backfill

2015 ◽  
Vol 52 (12) ◽  
pp. 1901-1912 ◽  
Author(s):  
James P. Doherty ◽  
Alsidqi Hasan ◽  
Gonzalo H. Suazo ◽  
Andy Fourie
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Cement Content ◽  
Water Pressure ◽  
Cemented Paste Backfill ◽  
Total Stress ◽  
Rest Periods ◽  
Rate Of Increase ◽  
Controllable Factors ◽  
Paste Backfill

This paper presents in-stope measurements of total stress and pore-water pressure at strategic locations within three underground stopes at the Raleigh mine site (Western Australia) that were filled with cemented paste backfill (CPB). The three stopes were very similar in shape. Key differences among the stopes were the filling and resting schedules, the barricade drainage systems used, and the cement content of the CPB. Data from the stopes are compared to determine which controllable factors most significantly influence barricade pressures during and after filling. The most significant factor was the scheduling of rest periods between filling, with even very short pauses in filling dramatically reducing the rate of increase of pore-water pressure and total stress with increasing height of fill.

scholarly journals Effect of the Initial Air Content in Fresh Slurry on the Compressive Strength of Hardened Cemented Paste Backfill

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Youzhi Zhang ◽  
Deqing Gan ◽  
Zhenlin Xue ◽  
Xun Chen ◽  
Sheng Hu
Keyword(s):  
Compressive Strength ◽  
Sodium Dodecyl ◽  
Contact Structures ◽  
Cemented Paste Backfill ◽  
Mining Method ◽  
Force Analysis ◽  
Air Content ◽  
Ground Pressure ◽  
Paste Backfill ◽  
The Mathematical Model

Filling mining method can dispose of the tailings into filling slurry, which can be transported to the stope through pipelines to manage the ground pressure and protect the environment. To improve the flowability of filling slurry, additives are used more and more widely. However, some additives can increase the air content in the slurry. The air in the slurry will become pores in the hardened cemented paste backfill (CPB). Therefore, it is necessary to explore the influence of initial air content in fresh slurry on the compressive strength of CPB. In this paper, sodium dodecyl sulfate (SDS) was used to regulate the air content in the fresh slurry. After measuring the initial air content, the slurry was made into test blocks. Then, the uniaxial compressive strength (UCS) of CPB at 28 d age was tested, and the distribution of CPB microscopic pores was observed by scanning electron microscope (SEM). The results show that as the initial air content in fresh slurry increases, the UCS of CPB first increases and then decreases. Before the initial air content in fresh slurry is 6.03%, the CPB pores distribution is relatively uniform. However, after exceeding this value, “discontinuous contact” structures, pore groups, and macropores occur in CPB. Through the CPB microscopic force analysis, the mathematical model describing the effect of initial air content on UCS of CPB should be a combination of logarithmic function and quadratic polynomial. This work can provide a supplement to the theory of CPB strength.

Fluidity and Mechanical Behavior of Cement Solidified Lead-Zinc Mine Tailings

2014 ◽  
Vol 898 ◽  
pp. 383-386 ◽  
Author(s):  
Chun Lei Zhang ◽  
Shun Cai Wang ◽  
Fan Lu Min
Keyword(s):  
Mine Tailings ◽  
Cement Content ◽  
Strength Increase ◽  
Cemented Paste Backfill ◽  
Curing Time ◽  
Test Results ◽  
The World ◽  
Paste Backfill ◽  
Lead Zinc ◽  
Zinc Mine

Cemented paste backfill method has been widely used in many modern mines throughout the world due to the increasingly stringent environmental regulations and short of disposal land. This study presents experimental results on the use of Portland cement in the solidification of Pb-Zn tailings in China. Test results show UCS strength increase lineally with cement content, tailings concentration, and curing time, respectively. There exist a minimum cement content and tailings concentration to produce obvious strength. The fluidity decrease quickly with cement proportion and tailings concentration, under the satisfying of a minimum pumping fluidity, the increase of tailings concentration can effectively reduce the cement consumption so as to decrease the treatment cost.

scholarly journals Properties of Gobi Aggregate and Sulfide-Rich Tailings Cemented Paste Backfill and Its Application in a High-Stress Metal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
D. Q. Deng ◽  
Y. H. Liang ◽  
F. C. Huangfu
Keyword(s):  
Cement Content ◽  
High Stress ◽  
Cemented Paste Backfill ◽  
Metal Mine ◽  
Mine Roadway ◽  
Backfill Materials ◽  
Paste Backfill ◽  
Production Requirement ◽  
Addition Amount ◽  
Future Utilization

This experiment studied the influence law of the strength of CPB affected by tailings content, Gobi aggregate content, cement content, and slurry concentration. The results show, for the CPB with concentration of 77%, when the addition amount of cement reaches 20%, the addition amounts of tailings and Gobi aggregate change within the ranges of 12∼24% and 56∼68%, respectively. The strength of CPB has been gradually improved when the addition amount of Gobi aggregates decreases and the addition amount of tailings increases. In this case, the slump of CPB changes within the range of 26.5 cm∼26.9 cm while the strength of CPB changes within the range of 4.021∼6.845 MPa. Considering future utilization value of tailings, the addition amount is finally set at 16% in production, and the addition amount of Gobi aggregate is set at 64%; namely, tailings: Gobi aggregate = 20 : 80. When the addition amount of cement is 20% (cement/(tailings + Gobi aggregates) = 1 : 4), the strength of CPB reaches 5.62 MPa which meets the production requirement. When the heading machine is used for tunnelling mine roadway in bottom backfill of VCR stope, no collapse or delamination occurs without support, showing good stability and integrity of backfill. When the adjacent stope ore is mined, the backfill with cement content of 11.1%, 14.3%, 20%, and 25% is exposed. In the process of mining, no collapse or delamination occurs. Therefore, the proportion of various backfill materials applied in production is reasonable, being verified by the experiment and field test.

3D numerical modeling of road tunnel stability – The Laliki project / Modelowanie 3D DLA oceny stateczności tunelu drogowego w Lalikach

2012 ◽  
Vol 57 (1) ◽  
pp. 61-78 ◽  
Author(s):  
Tadeusz Majcherczyk ◽  
Zbigniew Niedbalski ◽  
Michał Kowalski
Keyword(s):  
Numerical Modeling ◽  
Mining Method ◽  
Detailed Data ◽  
Road Tunnel ◽  
3D Numerical Modeling ◽  
Unique Case ◽  
Tunnel Stability ◽  
Tunnel Design ◽  
Arch Support ◽  
Geotechnical Evaluation

The paper presents an evaluation of 3D numerical modeling of the first road tunnel built mining method in Poland, on the Polish-Slovakian border. The Laliki tunnel presents a unique case for an assessment of 3D numerical modeling as a tool for tunnel design due to detailed data being available from monitoring during construction. Geotechnical evaluation carried out for the project proved insufficient, which called for an urgent necessity to work out an additional reinforcement of preliminary lining, using forepoling as the arch support. Stability analyses of the tunnel with new lining were carried out on the basis of 3D numerical modeling of displacements and stresses around the tunnel.

scholarly journals Experimental Investigation on Strength and Failure Characteristics of Cemented Paste Backfill

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhihong Zhang ◽  
Jiacheng Li
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Uniaxial Compressive Strength ◽  
Cement Content ◽  
Confining Pressure ◽  
Curing Temperature ◽  
Cemented Paste Backfill ◽  
Upward Trend ◽  
Paste Backfill ◽  
Curing Age

The strength characteristics of cemented paste backfill (CPB) in mining areas are key control factors for the safety assessment of overlying strata. A series of experiments about uniaxial compression and triaxial compression were carried out to study the influence of cement content of filling slurry, curing age, and curing temperature on strength behavior of CPB specimens. The failure mechanism and damage feature of CPB have been investigated. The results show the following: (1) The uniaxial compressive strength of CPB specimens exhibits an upward trend with the increase of cement content and curing age. When the cement content is high, the uniaxial compressive strength increases sharply with increasing curing age. (2) The cohesion of CPB specimens increases with the increase of cement content of filling slurry, curing age, and curing temperature. The cohesion of CPB specimens with curing age 7 days and 14 days increases linearly with increasing cement content. At the later stage of curing age, the strength growth of high cement content backfill is significantly greater than that of low cement content. The internal friction angle of the filling increases slightly with increasing filling cement content, curing age, and curing temperature. (3) The shear strength of CPB specimens at curing age 7 days exhibits an upward trend with the increase of confining pressure, while the shear strength at 14 days and 28 days curing age decreases slightly as the confining pressure increases. (4) With the increase of cement content in backfill, the brittleness increases significantly when the backfill is damaged. The failure mode of CPB specimens changes from monoclinic section shear failure to X-type failure with increasing curing age, and the failure process is divided into four stages: pore compaction, linear elastic deformation, plastic deformation, and post-peak failure.

Floor damage mechanism with cemented paste backfill mining method

2021 ◽  
Vol 14 (2) ◽  
Author(s):  
Xianyuan Shi ◽  
Huaqiang Zhou ◽  
Xikui Sun ◽  
Zhong Cao ◽  
Qingmin Zhao
Keyword(s):  
Damage Mechanism ◽  
Cemented Paste Backfill ◽  
Mining Method ◽  
Backfill Mining ◽  
Paste Backfill
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