Nonlinear Large Deformation Mechanism and Stability Control of Deep Soft Rock Roadway: A Case Study in China

Wang, Dong; Jiang, Yujing; Sun, Xiaoming; Luan, Hengjie; Zhang, Hui

doi:10.3390/su11226243

Cited by 20 publications

(13 citation statements)

References 19 publications

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“…Rocks surrounding the coal seams are generally very weak [3,7]. Increasing mining depth due to high in-situ stress, high overburden, and tectonic stress causes the surrounding rock to undergo large nonlinear deformation [8], making it soft [9], e.g., the Pingdingshan mining area [10], Yili No. 1 Coal Mine [11], Xiaokang Coal Mine [12], Xin'an coal mine in Gansu Province [13,14].…”

Section: Introductionmentioning

confidence: 99%

Large Deformation Characteristics of Surrounding Rock and Support Technology of Shallow-Buried Soft Rock Roadway: A Case Study

Zhu

Yao

et al. 2022

Applied Sciences

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The coal resources in the coal-rich area of western China are mostly located in the late diagenetic Cretaceous and Jurassic strata. In this paper, a study on the support of soft rock roadways was carried out in the background of the soft rock track roadway in the Jiebangou coal mine. The field investigation showed that the surrounding rocks of the roadway were weak, soft, and broken, and the surrounding rocks were cemented, with the roadway local deformation exceeding 1 m. The borehole television results showed that the surrounding rocks were mainly weak sandy mudstone and yellow mudstone. The average uniaxial compressive strength of the surrounding rock was 15.49 MPa. The roadway is a shallow buried soft rock roadway; site investigation revealed that the original U-shaped steel shed had an extremely low resistance to slip, the filling body behind the U-shaped steel shed fell off, the interaction between the U-shaped steel shed and the surrounding rock was poor, the U-shaped steel shed could not provide sufficient timely support resistance, and the bearing capacity of the U-shaped steel shed was far from consideration. The floor was not effectively supported. The floor had different degrees of the bottom drum, and frequent undercover caused new stress disturbances, which loosened the bottom corners of both rock types and made the shed legs move continuously inward, reducing the bearing capacity and actual support resistance of the bracket. Numerical calculations were performed to study the deformation characteristics of the surrounding rock of the tunnel and the yielding damage characteristics of the brace. The results showed that the current U-shack support strength was insufficient, the two sides were deformed by 950 mm, the bottom of the roadway bulged by 540 mm, and the surrounding rock was mainly shear damaged. The fall of the filler behind the shed caused damage to the U-shaped steel shed spire. Through site investigation results and numerical calculations, the deformation and damage characteristics of the soft rock roadway and its damage causes were analyzed, and the support technology system of ‘strengthening support for weak structural parts’ was proposed. This improved the mechanical properties of the weak structural support body, the stress state of the local surrounding rock, and the bearing capacity of the support structure, and effectively controlled the deformation, damage, and instability of the surrounding rock of the roadway, and deformation, damage, and destabilization of the roadway, thereby achieving overall stability for the surrounding rock of the roadway.

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Section: Introductionmentioning

confidence: 99%

Large Deformation Characteristics of Surrounding Rock and Support Technology of Shallow-Buried Soft Rock Roadway: A Case Study

Zhu

Yao

et al. 2022

Applied Sciences

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“…Under the mutual superposition of high ground stress and strong mining stress, the roadway and surrounding rock masses generally have problems such as the strength deterioration of surrounding rock, deterioration of the stress environment, and structural instability and large deformation of surrounding rocks [4][5][6]. In severe cases, roof fall and slabs may occur [7,8].…”

Section: Introductionmentioning

confidence: 99%

Full-Stress Anchoring Technology and Application of Bolts in the Coal Roadway

et al. 2021

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The traditional anchoring method of bolts has insufficient control over the surrounding rock of the coal roadway. Based on this background, full-stress anchoring technology of bolts was proposed. Firstly, a mechanical relationship model of a bolt-drawing, anchoring interface was established to obtain the equations of the axial force and obtain shear stress distribution as well as the decreasing-load transfer law of the anchoring section of bolts. Through studying the prestress-loading experimental device of bolts, we found that increasing the initial preload could increase the axial force under the same conditions and the retarded anchoring section could control the axial-force loss of bolts in the middle of the anchoring section. Under the full-stress anchoring mode, the effect of applying a pre-tightening force was better than that of applying a pre-tightening force under traditional anchoring methods. Moreover, FLAC3D (Fast Lagrangian Analysis of Continua 3D; ITASCA (Ita sca International Inc), Minnesota, USA) numerical simulation calculation was performed. Under the full-stress anchoring mode of bolts, the increased anchoring length reduced the damage of the anchoring section, with a wider control range of the rock formation and higher strength of the compressive-stress anchoring zone. Based on the above research, four methods for applying the full-stress anchoring technology of bolts in engineering were proposed. The full-stress anchoring technology of bolts in the coal roadway has been applied in the support project of the return-air roadway at working face 3204 of the Taitou Coking Coal Mine of the Xiangning Coking Coal Group, Shanxi. The maximum moving distance of the roof and floor of the roadway was reduced from 200 to 42 mm, and the maximum moving distance on both coal sides was reduced from 330 to 86 mm. The full-stress anchoring technology of bolts was able to control the surrounding rock in the coal roadway.

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“…To cope with the damage caused by the large deformation of the soft rock, several coping methods have been proposed in engineering practice and theoretical research [20][21][22][23][24]. Zhang et al [25] believed that setting the reserved deformation in the tunnel support structure can effectively reduce the damage caused by the large deformation of the soft rock tunnel, and the reserved deformation should be set between the initial support and secondary lining.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Stress and Deformation Characteristics of Deep‐Buried Phyllite Tunnel Structure under Different Cross‐Section Forms and Initial Support Parameters

Yang

Cai

et al. 2021

Advances in Civil Engineering

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Deep-buried soft rock tunnels exhibit low strength and easy deformation under the influence of high ground stress. The surrounding rock of the soft rock tunnel may undergo large deformation during the construction process, thereby causing engineering problems such as the collapse of the vault, bottom heave, and damage to the supporting structure. The Chengwu Expressway Tunnel II, considered in this study, is a phyllite tunnel, with weak surrounding rock and poor water stability. Under the original design conditions, the supporting structure exhibits stress concentration and large deformation. To address these issues, three schemes involving the use of the double-layer steel arch to support, weakening of the steel arch close to the excavation surface, and weakening of the steel arch away from the excavation surface to support were proposed. Using these schemes, the inverted radius was varied to explore its influence on different support schemes. For simulation, the values of the inverted radius selected were as follows: 1300 cm, 1000 cm, and 700 cm. The proposed support plan was simulated using FLAC3D, and the changes in the pressure between the initial support and surrounding rock, the settling of the vault, and the surrounding convergence were investigated. The numerical simulation results of monitoring the surrounding rock deformation show that the double-layer steel arch can effectively reduce the large deformation of the soft rock well. When the stiffness of one of the steel arches was weakened, the support’s ability to control the deformation was weakened; however, it still showed reliable performance in controlling deformation. However, changing the radius of the invert had an insignificant effect on the deformation and force of the supporting structure.

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Nonlinear Large Deformation Mechanism and Stability Control of Deep Soft Rock Roadway: A Case Study in China

Cited by 20 publications

References 19 publications

Large Deformation Characteristics of Surrounding Rock and Support Technology of Shallow-Buried Soft Rock Roadway: A Case Study

Large Deformation Characteristics of Surrounding Rock and Support Technology of Shallow-Buried Soft Rock Roadway: A Case Study

Full-Stress Anchoring Technology and Application of Bolts in the Coal Roadway

Analysis of Stress and Deformation Characteristics of Deep‐Buried Phyllite Tunnel Structure under Different Cross‐Section Forms and Initial Support Parameters

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