Stability Analysis and Control Measures of Large-Span Open-Off Cut with Argillaceous Cemented Sandstone Layered Roof

Zheng, Weiye; Guo, Yujie; Zhi, Guojun; Bao, Xiankai; Sun, Ming; Ren, Ruiping; Duan, Zhi-jun; Gao, Zhendong

doi:10.1155/2021/8744081

Cited by 5 publications

(1 citation statement)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous scholars have carried out a large number of researches on roof instability mechanism of different strata structures by using the on-site monitoring, similarity simulation, and numerical simulation methods. The roof rock strata structures mainly included upper-soft and lowerhard strata, upper-hard and lower-soft strata, containing faults strata, and regenerated roof strata as well as laminated-jointed roof strata [6][7][8][9][10][11]. Above research results showed that the characteristics of roof strata structure have a significant impact on the roof instability mode of roadway, especially for large-span roadway.…”

Section: Introductionmentioning

confidence: 85%

Field Detection and Numerical Simulation Study on Roof Asymmetric Fracture Mechanism of Large-Span Soft Rock Roadway with Discontinuity Surface

et al. 2022

View full text Add to dashboard Cite

Existence of roof discontinuity surface is one of the extremely important factors causing the asymmetric fracture of roadway roof, especially for large-span soft rock roadway. In this paper, a crack density coefficient ( D ) is firstly defined by local thresholding-microcell segmentation method and used to analyze the evolution law of D with roof drilling depth ( d ) (the lower and upper of roof discontinuity are defined as regions I and II, respectively). Then, UDEC numerical simulation is used to investigate the asymmetry evolution law of roof total displacement, maximum principal stress, and crack density with stress release coefficient ( α ) considering the effect of discontinuity surface. Research results indicate that (1) the roof parameters (D) in regions I and II both show a negative logarithmic function decreasing trend with the increase of drilling depth. When d < 4.5 m, the parameter ( D ) in region II is about 1.5 times that in region I; when d ≥ 4.5 m, the parameter ( D ) in region I is almost zero, while the parameter ( D ) in region II maintains a slight decreasing trend. Roof failure presents asymmetric distribution characteristics along both sides of the discontinuous surface. (2) In the initial stage of open-off cutting excavation, the top left and right corners of roof as well as the bottom of discontinuous surface first occurred the tension-shear failure, and then as the α increases, the two side cracks gradually shift to the middle of roof in regions I and II with the appearance of stress concentration in two top corners. Meanwhile, the direction of maximum principal stress is transformed from “direction approximately parallel to the excavation surface” to “direction perpendicular to the discontinuous surface,” of which the location transfers to the deep anisotropically, forming an asymmetric stress loosening zones in the roof of regions I and II. The range of stress loosening zone in region II is significantly larger than that in region I. When the surrounding rock stress is completely released, the roof cracks in region I gradually transition from nonconnected to connected state and form a “quasi-right triangle” loosening zone. In addition, an “isosceles triangle-like” high crack density loosening zone with the roof middle as the axis is also formed in region II. The roadway roof presents a markedly asymmetric caving feature. (3) With the increase of discontinuity surface angles, the roof fracture range gradually decreases in region I and increases in region II as well as the structural features of roof pressure-bearing arch transform from “left-low right-high continuous asymmetric structure” (30°-60°) to “left-low right-high discontinuous asymmetric structure” (90°) to “unilateral partial pressure-bearing arch structure” (120°-150°). Research results can provide an extremely important reference for the optimization and design of support scheme with discontinuity-thick soft rock roof-large span roadways.

show abstract

Section: Introductionmentioning

confidence: 85%

Field Detection and Numerical Simulation Study on Roof Asymmetric Fracture Mechanism of Large-Span Soft Rock Roadway with Discontinuity Surface

et al. 2022

View full text Add to dashboard Cite

show abstract

Research on the technology of gob-side entry retaining by pouring support beside the roadway in “three soft” coal seam: A case study

Fu,

Chen,

et al. 2024

Physics of Fluids

View full text Add to dashboard Cite

This paper's goal is to investigate if a gob-side entry retention technique combined with a surrounding rock support system is feasible in three soft coal seams. Field engineering confirmed the results of numerical simulation tests and similar simulation tests, which were conducted in accordance with the actual geological conditions of Zhaojiazhai Mine. The following conclusions are reached after studying the technology and process parameter of the gob-side entry retaining in three soft coal seams in conjunction with theoretical calculations: the coal seam of Zhaojiazhai Coal Mine's 12 209 working face is a part of the soft coal seam, and its loose circle is approximately 1.8 m. The expansion roadway size is 3.5 m, and the potential loose circle range is 1.32 m, according to the same model and numerical simulation test. The support scheme after the expansion of the road working face is determined to be the “anchor rod + anchor cable + hydraulic lifting shed” support method. Furthermore, this article suggests a building method for the reinforcement and enlargement of gob-side entry retaining in three-soft thick coal seam by theoretical analysis and numerical simulation. Roadway shotcrete, advance grouting, building of a large deformation anchor cable and continuous resistance, single column lifting shed, hydraulic lifting shed, and roadway enlargement in advance are all steps in the procedure. Furthermore, an analysis is conducted on the deformation features of the surrounding rock in gob-side entry retention. The study highlights the significance of actively supporting the surrounding rock, fortifying the roof support, guaranteeing the stiffness compatibility between the shoulder filling body and the surrounding rock on the roof, boosting the wall's strength and stability, and enhancing the roadway's stability.

show abstract

Shape Design and Support Scheme of Roadways in Stratified Rock Masses: Based on Numerical Experiments and Field Case Studies

Li,

Zhang,

Sun

et al. 2024

Advances in Civil Engineering

View full text Add to dashboard Cite

The deformation and failure characteristics of roadways in stratified rock masses are heavily influenced by the dip angle of the rock layers. Therefore, it is crucial to select an appropriate cross‐sectional shape and support scheme to ensure roadway stability. This study utilizes a discrete element numerical simulation method to systematically investigate the failure modes of roadways in stratified rock masses under varying dip angles. The theory of pressure balance arches is integrated to establish optimal principles for determining the cross‐sectional shape, and corresponding support schemes are proposed for roadways in stratified rock masses. The results indicate that as the dip angle of the rock layers changes, different failure modes occur, ranging from symmetric arch‐shaped collapse to asymmetric wedge‐shaped collapse and overall sliding failure. Based on the self‐stabilizing properties of roadways under pressure balance arches, a straight‐sidewalls and arch‐roof cross‐section is recommended for roadways with arch‐shaped or overall sliding failures in their roofs, and a pentagonal cross‐section is recommended for roadways with wedge‐shaped collapses. The support parameters determined by well‐established empirical criteria are generally applicable to roadways with arch‐shaped or wedge‐shaped roof failures. However, caution should be exercised when applying these parameters to roadways with overall sliding instabilities, as they may result in insufficient design robustness. Finally, a field case study of a copper mine in Zambia is presented to demonstrate the process of recommending appropriate roadway cross‐sectional shape and support scheme.

show abstract

Stability Analysis and Control Measures of Large-Span Open-Off Cut with Argillaceous Cemented Sandstone Layered Roof

Cited by 5 publications

References 26 publications

Field Detection and Numerical Simulation Study on Roof Asymmetric Fracture Mechanism of Large-Span Soft Rock Roadway with Discontinuity Surface

Field Detection and Numerical Simulation Study on Roof Asymmetric Fracture Mechanism of Large-Span Soft Rock Roadway with Discontinuity Surface

Research on the technology of gob-side entry retaining by pouring support beside the roadway in “three soft” coal seam: A case study

Shape Design and Support Scheme of Roadways in Stratified Rock Masses: Based on Numerical Experiments and Field Case Studies

Contact Info

Product

Resources

About