scholarly journals A Case Study on Gob-Side Entry Retaining Technology in the Deep Coal Mine of Xinjulong, China

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Ping Wang ◽  
Li Ding ◽  
Yuan-jun Ma ◽  
Tao Feng ◽  
Guang-jing Sun ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Coal Mine ◽  
Steel Tube ◽  
Actual Measurement ◽  
Deep Mining ◽  
Concrete Filled Steel Tube ◽  
Backing Plate ◽  
Anchor Cable ◽  
Working Face ◽  
Mining Face

Through the analysis of the project of gob-side entry retaining in the deep gangue filling 2305S-2# working face of the Xinjulong coal mine, the principle and technology of surrounding rock control of gob-side entry retaining along the deep mining face are discussed. It is found that the use of gangue to fill the goaf of the deep mining face can effectively alleviate the occurrence of violent strata pressure, which is the basis for realizing entry retaining along the goaf. In the Xinjulong coal mine, the gangue wall and concrete-filled steel tube columns are used as roadside support structure. Anchor bolt + W steel belt are used as advance support, monomer column + hinged beam are used as temporary support, and long anchor cable + beam are used as permanent support. Gob-side entry retaining of deep mining working face is successfully realized. The actual measurement results show that the bearing capacity of gangue wall increases slowly, and the deformation is large. The concrete-filled steel tube column has a certain drilling bottom, and the roof cable is easily broken on the side of the remaining roadway. It is necessary to strengthen the lateral constraint of the gangue wall, limit the deformation of the gangue wall, and improve the bearing capacity of the gangue wall. The bottom of the concrete-filled steel tube column needs to be installed with a large backing plate to control the bottom drilling amount, and the roof anchor cable of the roadway must have a certain elongation to realize the coordinated deformation of the anchor cable and the roof.

scholarly journals Characteristics of New Permanent Magnetic Eddy Current Drive System of the Scraper Conveyor

2021 ◽  
Author(s):  
shuang wang ◽  
Yongcun GUO ◽  
Deyong LI
Keyword(s):  
Eddy Current ◽  
Coal Mine ◽  
Mining Area ◽  
Current Drive ◽  
Drive System ◽  
Model Accuracy ◽  
Working Face ◽  
Scraper Conveyor ◽  
Mining Face ◽  
Motion Characteristics

Abstract This study provides a new permanent magnetic eddy current drive system to solve the ener-gy-saving drive problem of the scraper conveyor working under bad conditions, including overload startup, severe abrasion and pollution. Considering the practical conveying conditions of the scraper chain on a fully mechanised coal mining face, this study creates a mathematical model for the new permanent magnetic eddy current drive system of the scraper conveyor based on its characteristics and indicates the motion characteristics of the scraper chain driven by two wheels. This study verifies the model accuracy with a pre-startup technology depending on the scraper conveyor on the No. 12318 working face of the 8th coal mine in the West No. 1 mining area of the Pansan Coal Mine of the Huainan Mining Group. According to the results, the motion acceleration of the scraper chain based on the new permanent magnetic eddy current drive is lower than that of the scraper chain with a hydraulic coupler under the same running condition and load during startup and acceleration and declines by approximately 14.7%. Consequently, this can decline the startup impact due to the serious abrasion and frequent overload of the scraper chain working under bad conditions.

Bearing capacity of composite shear wall incorporating a concrete-filled steel tube boundary and column-type reinforced wall

2020 ◽  
Vol 23 (10) ◽  
pp. 2188-2203
Author(s):  
Zhao Nannan ◽  
Wang Yaohong ◽  
Han qing ◽  
Su Hao
Keyword(s):  
Bearing Capacity ◽  
Residual Deformation ◽  
Shear Walls ◽  
Shear Wall ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Composite Shear Wall ◽  
Boundary Shear ◽  
Column Type ◽  
Composite Shear

Composite shear walls are widely used in high-rise buildings because of their high bearing capacity. To improve the bearing capacity of ordinary shear walls, restraining elements are usually installed at both boundaries or within the wall body. In this article, two different restraining elements, namely, a rectangular steel tube and a column-type reinforcement (the whole wall body was restrained by segmented stirrups and tied by diagonal bars), were applied to the boundary frame and wall body of the shear wall either jointly or separately. A new type of steel-concrete composite shear wall, referred to as a composite shear wall incorporating a concrete-filled steel tube boundary and column-type reinforced wall, was proposed. In addition, three specimens with different restraining elements, namely, a column-type reinforced shear wall, a concrete-filled steel tube boundary shear wall and an ordinary reinforced concrete shear wall, were presented for comparison. The influences of the two different restraining elements on the seismic performance and bearing capacity of the shear walls were analyzed from four perspectives of failure mode, hysteresis behavior, stiffness and residual deformation, and the equivalent lateral pressures of the two restraining elements were calculated. Based on the plane-section assumption, expressions for the crack, yield, peak and ultimate bearing capacities were derived, and the effects of the two restraining elements on the peak and ultimate bearing capacities were considered. The results show that these two restraining elements significantly improved the bearing capacity of the shear wall specimens, and the concrete-filled steel tube restraining element was more effective than the column-type reinforced restraining element. Finally, the calculated values of the bearing capacity of the four different restraining elements of the shear wall specimens proposed in this article were in good agreement with the experimental values.

Study of the Ultimate Bearing Capacity of Concrete-filled Steel Tube K-Joints

2019 ◽  
Vol 23 (5) ◽  
pp. 2254-2262 ◽  
Author(s):  
Kaizhong Xie ◽  
Hongwei Wang ◽  
Jinhao Pang ◽  
Jianxi Zhou
Keyword(s):  
Bearing Capacity ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Concrete Filled Steel Tube

Axial behaviour of slender concrete-filled steel tube square columns strengthened with square concrete-filled steel tube jackets

2019 ◽  
Vol 23 (6) ◽  
pp. 1074-1086 ◽  
Author(s):  
Tao Zhu ◽  
Hongjun Liang ◽  
Yiyan Lu ◽  
Weijie Li ◽  
Hong Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Bearing Capacity ◽  
Element Model ◽  
Steel Tube ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Concrete Filled Steel Tube ◽  
Experimental Parameters ◽  
Modified Formula

This article investigates the behaviour of slender concrete-filled steel tube square columns strengthened by concrete-filled steel tube jacketing. The columns were realised by placing a square outer steel tube around the original slender concrete-filled steel tube column and pouring strengthening concrete into the gap between the inner and outer steel tubes. Three concrete-filled steel tube square columns and seven retrofitted columns ranging from 1200 to 2000 mm were tested to failure under axial compression. The experimental parameters included three length-to-width ( L/ B1) ratios, three width-to-thickness ( B1/ t1) ratios and three strengths of concrete jacket (C50-grade, C60-grade and C70-grade). Experimentally, the retrofitted columns failed in a similar manner to traditional slender concrete-filled steel tube columns. After strengthening, the retrofitted columns benefitted greatly from the component materials, with their load-bearing capacity and ductility notably enhanced. These enhancements were mainly brought about by sectional enlargement and good confinement of concrete. A finite element model was developed using ABAQUS to better understand the axial behaviour of the retrofitted specimens. A parametric study was conducted, with parameters including the length of the column, thickness of the outer steel tube, strength of the concrete jacket, yield strength of the outer steel tube, thickness of the inner steel tube and strength of the inner concrete. Furthermore, the finite element model was adopted to study the behaviour of rust-damaged and post-fire slender concrete-filled steel tube square columns strengthened by square concrete-filled steel tube jacketing. A modified formula was proposed to predict the load-bearing capacity of retrofitted specimens, and the numerical results agreed well with the experiments and the finite element results of undamaged, rust-damaged and post-fire specimens. It could be used as a reference for practical application.

The Research on Geological Characteristics of the Dafosi Coal Mine Company 40110 Working Face

2012 ◽  
Vol 170-173 ◽  
pp. 1273-1276
Author(s):  
Jia Ming Han
Keyword(s):  
Coal Mine ◽  
Relative Movement ◽  
Practical Application ◽  
Wing Area ◽  
Daily Production ◽  
The Third ◽  
Geological Characteristics ◽  
Working Face ◽  
Sublevel Caving ◽  
Mining Face

40110 working face is arranged as the third Mechanized sublevel caving mining face in the 401 east-wing area along the coal seam by Dafosi company of the Binchang Mining Group Corporation. According to the conclusion based on the research about Binchang area coal geology not only shows the roof and floor lithology, structure, hydrology, the gas, dust features and so on but also proposes mining roadway supporting schemes and putting them into practice. Practical application shows that roadway supporting schemes effectively control the two-sided displacement and relative movement of the roof and floor to ensure the daily production of coal mine.

scholarly journals The Horizontal Bearing Capacity of Composite Concrete-Filled Steel Tube Piles

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yunxiu Dong ◽  
Zhongju Feng ◽  
Haibo Hu ◽  
Jingbin He ◽  
Qilang Zhang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Soil Compaction ◽  
Soil Mass ◽  
Steel Tube ◽  
Continuous Increase ◽  
Concrete Filled Steel Tube ◽  
Concrete Piles ◽  
Compaction Zone ◽  
Reinforced Concrete Piles ◽  
Centrifugal Model

Steel casings (SCs) are extensively and increasingly used to stabilize the borehole wall in the construction of bridge pile foundations. Steel casings (SCs), together with reinforced concrete piles (RCPs), form composite concrete-filled steel tube piles (CCFSTPs), which differ significantly from ordinary RCPs in horizontal bearing capacity. In this study, based on the characteristics of CCFSTPs, the horizontal bearing capacity of a CCFSTP was examined through a centrifugal model test with the length of the steel casing (LSC) and the modulus of the soil mass in the steel casing soil compaction zone (ESCSC_zone) as variables. Pile-side soil resistance, load-displacement curves, and pile moment curves were obtained for the CCFSTP. The results show that increasing LSC within a range of 12 cm significantly increases the ultimate horizontal bearing capacity of the CCFSTP, and further increasing LSC beyond 12 cm produces a continuous increase in the ultimate horizontal bearing capacity of the CCFSTP but only to an insignificant extent. In addition, increasing ESCSC_zone increases the ultimate horizontal bearing capacity of the CCFSTP, but to a relatively small extent. The results of this study provide a theoretical basis and technical support for the design and construction of CCFSTPs.

scholarly journals Axial Compression Performance of Square Thin Walled Concrete-Filled Steel Tube Stub Columns with Reinforcement Stiffener under Constant High-Temperature

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1098 ◽  
Author(s):  
Xuetao Lyu ◽  
Yang Xu ◽  
Qian Xu ◽  
Yang Yu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Bearing Capacity ◽  
Numerical Models ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Displacement Curve ◽  
Concrete Filled Steel Tube ◽  
Finite Element Software ◽  
Thin Walled

This study investigated the axial compressive performance of six thin-walled concrete-filled steel tube (CFST) square column specimens with steel bar stiffeners and two non-stiffened specimens at constant temperatures of 20 °C, 100 °C, 200 °C, 400 °C, 600 °C and 800 °C. The mechanical properties of the specimens at different temperatures were analyzed in terms of the ultimate bearing capacity, failure mode, and load–displacement curve. The experiment results show that at high temperature, even though the mechanical properties of the specimens declined, leading to a decrease of the ultimate bearing capacity, the ductility and deformation capacity of the specimens improved inversely. Based on finite element software ABAQUS, numerical models were developed to calculate both temperature and mechanical fields, the results of which were in good agreement with experimental results. Then, the stress mechanism of eight specimens was analyzed using established numerical models. The analysis results show that with the increase of temperature, the longitudinal stress gradient of the concrete in the specimen column increases while the stress value decreases. The lateral restraint of the stiffeners is capable of restraining the steel outer buckling and enhancing the restraint effect on the concrete.

Coupled bending-shear-torsion bearing capacity of concrete filled steel tube short columns

2018 ◽  
Vol 123 ◽  
pp. 305-316 ◽  
Author(s):  
Nie Xin ◽  
Wang Yu-Hang ◽  
Li Shuo ◽  
Chen Ju
Keyword(s):  
Bearing Capacity ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Short Columns

Optimal Calculation Method of Eccentric Bearing Capacity of Concrete-Filled Steel Tube Short Columns

2012 ◽  
Vol 238 ◽  
pp. 666-668
Author(s):  
Jian Wei Zhang ◽  
Xing Jie Kuang ◽  
Wei Feng Bai ◽  
Juan Wang
Keyword(s):  
Experimental Data ◽  
Bearing Capacity ◽  
Engineering Design ◽  
Calculation Method ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Short Columns ◽  
Optimal Calculation

The currently formulae with many coefficients are too complicated to calculate the bearing capacity of concrete-filled steel tube (CFST) short columns. In this paper, an optimal calculation method was proposed for calculating the eccentric bearing capacity of CFST short columns by means of mechanical derivation. Additionally, the calculating results are compared with experimental data. It is shown that the optimal calculating formulae are highly accurate and easily applicable in engineering design.

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