Study on Mechanical Properties and Control Technology of Surrounding Rock in the Fracture Zone of a Roadway

We aim at the problem of the large deformation and difficult control of surrounding rock when passing through a fault fracture zone in the centralized rail transportation lane along the south wing of Xinyi Coal Mine; the stress environment and failure mechanism of surrounding rock are analyzed through field investigation, numerical simulation, and field industrial test. The instability of the surrounding rock in the fault fracture zone was considered to be the result of the joint effect of the surrounding rock fracture development, lithology differences, water gushing occurrences, low strength of the original support, high in situ stress, and fault-related tectonic stress. Rock blocks are collected on site at the fracture zone, and the remoulded samples are prepared for mechanical experiments in the laboratory. The basic mechanical parameters of the roadway passing through silty mudstone, sand-mudstone interlayer, and fine sandstone were analyzed. A three-dimensional model is established to analyze the distributions of the stress, deformation, and plastic area in the surrounding rock mass after the tunnel passes through, considering both a single-rock mass and a multilayer-rock mass. Based on the above analysis, the “closed support + shotcrete + grouting + anchor mesh cable coupling support” is proposed. Three stations were arranged on site to observe the mine pressure, and the field industrial test shows that, within the 100 days of observation, the maximum roof-to-floor convergence is 38 mm, while the maximum horizontal convergence is 56 mm. The overall reinforcement effect of the roadway is good, the surface is smooth, and there is no phenomenon of concrete cracking and bolt fracture.

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Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

MINING INFORMATIONAL AND ANALYTICAL BULLETIN ◽

10.25018/0236-1493-2020-6-0-67-75 ◽

2020 ◽

pp. 67-75

Author(s):

Van Min Nguyen ◽

V. A. Eremenko ◽

M. A. Sukhorukova ◽

S. S. Shermatova

Keyword(s):

Rock Mass ◽

Cross Sections ◽

Tensile Strain ◽

Rock Fracture ◽

Strain Analysis ◽

Surrounding Rock ◽

Underground Excavation ◽

Secondary Stress ◽

Principal Stresses ◽

Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

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Study on the Geological Forecast and Treatment for Water-Bearing Fault of the Qingdao Kiaochow Bay Subsea Tunnel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.671-674.1114 ◽

2013 ◽

Vol 671-674 ◽

pp. 1114-1121

Author(s):

Zhi Peng Li ◽

Shu Cai Li ◽

Qing Song Zhang ◽

De Ming Wang ◽

Bing Hui ◽

...

Keyword(s):

Fracture Zone ◽

Surrounding Rock ◽

Tunnel Excavation ◽

Bearing Fault ◽

Grouting Material ◽

Fault Fracture Zone ◽

Analysis Of Results ◽

Subsea Tunnel ◽

The Stability ◽

Fissure Water

Water-bearing fault of subsea tunnel has fissure water developed, fractured surrounding rock with low strength, which gets a risk of sudden water inflow and affects the tunnel security. This paper takes the geological forecast and treatment for water-bearing fault of the Qingdao kiaochow bay subsea tunnel for example, according to the water assignment characteristics, using the detect method of TEM and advance borehole to make accurate decision for the position of water-bearing body、the scale of fracture zone and the inflow of water. Through the analysis of results, the grouting form, materials and parameters are chosen and adjusted. The grouting material seals the water flowing fracture, forming water-stopping curtain outside tunnel excavation contour line and strengthening the fault fracture zone to improve the stability of rock.

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Numerical Simulation of Ultra-Shallow Buried Large-Span Double-Arch Tunnel Excavated under an Expressway

Applied Sciences ◽

10.3390/app12010039 ◽

2021 ◽

Vol 12 (1) ◽

pp. 39

Author(s):

Jianxiu Wang ◽

Ansheng Cao ◽

Zhao Wu ◽

Zhipeng Sun ◽

Xiao Lin ◽

...

Keyword(s):

Fracture Zone ◽

Horizontal Displacement ◽

Surrounding Rock ◽

Spatial Effects ◽

Partition Wall ◽

Tunnel Support ◽

Large Span ◽

Construction Design ◽

Excavation Process ◽

Fault Fracture Zone

The temporal and spatial effects of a complicated excavation process are vital for an ultra-shallow buried large-span double-arch tunnel excavated under an expressway in service. Numerical simulations are urgent and necessary to understand the effect of the total construction process. Taking Xiamen Haicang tunnel as a research object, the total excavation process of three pilot tunnels and the three-bench reserved core soil method of an ultra-shallow buried large-span double-arch tunnel with a fault fracture zone under an expressway was simulated using software FLAC3D. The deformation of the surface, surrounding rock, underground pipelines, tunnel support structure and partition wall of the three pilot tunnels and the main tunnel was analyzed, and the dangerous areas and time nodes were obtained. When the tunnel was excavated to the fault fracture zone, the deformation of the surface and surrounding rock increased significantly. The rock and soil within 20 m behind the excavation surface of the pilot tunnel were greatly disturbed by the excavation. During the excavation of the main tunnel, the horizontal displacement of the middle partition wall moved slightly towards the main tunnel excavated first. The research results can provide a reference for the construction design of double-arch tunnels.

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Numerical Study on Zonal Disintegration of Deep Rock Mass Using Three-Dimensional Bonded Block Model

Advances in Civil Engineering ◽

10.1155/2019/3589417 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Qingteng Tang ◽

Wenbing Xie ◽

Xingkai Wang ◽

Zhili Su ◽

Jinhai Xu

Keyword(s):

Rock Mass ◽

Fracture Zone ◽

Numerical Study ◽

Confining Pressure ◽

Surrounding Rock ◽

Zonal Disintegration ◽

Block Model ◽

Deep Rock Mass ◽

Damaged Zone ◽

Deep Rock

Zonal disintegration, a phenomenon of fractured zones and intact zones distributed alternately in deep rock mass, is different from the excavation-damaged zone of shallow rock mass. In this study, bonded block model of 3DEC was employed to study the fracture mode and origination condition of zonal disintegration. Initiation, propagation, and coalescence progress of fracture around the roadway boundary under different triaxial stress conditions are elaborated. Numerical simulation demonstrated that zonal disintegration may occur when the direction of maximum principal stress is parallel to the roadway axis. It is interesting to find that the fracture around the roadway boundary traced the line of a spiral line, while slip-line fractures distributed apart from the roadway boundary. The extent of the alternate fracture zone decreased as the confining pressure increased, and alternate fracture zone was no longer in existence when the confining pressure reaches a certain value. Effects of roadway shape on zonal disintegration were also studied, and the results indicated that the curvature of the fracture track line tends to be equal to the roadway boundary in shallow surrounding rock of the roadway, while the fractures in deep surrounding rock seems unaffected by the roadway shape. Those findings are of great significance to support design of deep underground openings.

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Effect of a Fault Fracture Zone on the Stability of Tunnel-Surrounding Rock

International Journal of Geomechanics ◽

10.1061/(asce)gm.1943-5622.0000837 ◽

2017 ◽

Vol 17 (6) ◽

pp. 04016135 ◽

Cited By ~ 23

Author(s):

Yingchao Wang ◽

Hongwen Jing ◽

Haijian Su ◽

Jiangyue Xie

Keyword(s):

Fracture Zone ◽

Surrounding Rock ◽

Fault Fracture Zone ◽

The Stability

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Research on the Mechnical Characteristics of Primary Supports in Guanjiao Tunnel Fault Fracture Zone and its Influence Zone by Field Tests

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.105-107.1203 ◽

2011 ◽

Vol 105-107 ◽

pp. 1203-1210 ◽

Cited By ~ 1

Author(s):

Da Li ◽

Zhan Fu Luo ◽

Yong Sheng Li

Keyword(s):

Fracture Zone ◽

Field Tests ◽

Surrounding Rock ◽

Tunnel Construction ◽

Railway Tunnel ◽

Influence Zone ◽

Geological Conditions ◽

Fault Fracture Zone ◽

Under Construction ◽

Primary Support

The tunnel which excavated through the fault fracture zone is still one of the difficulties in the current tunnel construction. Guanjiao tunnel is the longest high-altitude tunnel in the world, and also the longest railway tunnel which is under construction in China. The 9# shaft which located in Erlang fault fracture zone with several faults, complicated geological conditions is difficult to excavate. In the representative section of F3 fault and its influence zone, F22 fault fracture zone, the monitoring tests on contact pressure between surrounding rock and primary support and stress of steel arch is conducted. According to the above monitoring results，the project recommendations are proposed to ensure the smooth construction of tunnel.

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Quantitative Study on Empirical Strength Parameters of Extremely Fractured Phyllite Based on Fractal Theory

Advances in Materials Science and Engineering ◽

10.1155/2021/2241351 ◽

2021 ◽

Vol 2021 ◽

pp. 1-14

Author(s):

Yongbin Xie ◽

Xiaoyu Yang ◽

Jianhua Dong ◽

Guosheng Liu

Keyword(s):

Fractal Dimension ◽

Fracture Zone ◽

Shear Test ◽

Fractal Theory ◽

Surrounding Rock ◽

Strength Parameter ◽

Strength Parameters ◽

Significant Difference ◽

Fault Fracture Zone ◽

Fractal Description

Extremely broken phyllite is widely distributed and is easily seen in engineering construction. Aiming at the problem that the empirical strength parameters of extremely broken surrounding rock have intense subjectivity and significant difference, based on the characteristics of the existence of particle group state in the highly broken surrounding rock, the fractal theory and large-scale direct shear test are used, the fractal description of polar broken phyllite samples with different pile numbers in fault fracture zone of Qinyu Tunnel is carried out, and the fractal dimensions and empirical strength parameters of each sample are determined. Based on a fractal description and large shear test, the functional relationship between fractal dimension and empirical strength parameter of extremely broken phyllite in fault fracture zone is established, and the quantitative value method of empirical strength parameter determined by fractal dimension of extremely broken phyllite is given, which provides ideas for the quantitative value of empirical strength parameter of the similar extremely broken surrounding rock.

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Experimental Study on Creep of Surrounding Rock Mass in Argillaceous Soft Rock Tunnel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.193-194.826 ◽

2012 ◽

Vol 193-194 ◽

pp. 826-830 ◽

Cited By ~ 1

Author(s):

Qiu Yan Fan ◽

Jia Yan Lu ◽

Zhen Zhu

Keyword(s):

Rock Mass ◽

Rock Fracture ◽

Soft Rock ◽

Creep Damage ◽

Surrounding Rock ◽

Laboratory Simulation ◽

Creep Process ◽

Laboratory Model ◽

Accelerated Creep ◽

Rock Tunnel

Due to the complexity of underground engineering, study on creep characteristics of surrounding rock mainly adopts laboratory simulation experiment. Recently, the similar materials are used to do the experiment both at home and abroad, yet it can't reflect the original nature and others of rock fissure in original rock mass. Through the field collection of undisturbed sample of Tertiary mudstone, the conclusions are made by laboratory model test on surrounding rock of underground tunnel and creep process regularity and failure mechanism in the surrounding rock in this paper as follows: there are three obvious stages of creep under certain stress levels, which is measured on the surface of surrounding rock mass in argillaceous soft rock tunnel--decay creep ,steady creep and accelerated creep. The surrounding rock will produce the accelerated creep damage when the stress level is over a threshold value. Creep damage of surrounding rock mainly includes the forms of roof sinking, floor working up, and forming a macro- fracture surfaces etc. Test results showed that the undisturbed surrounding rock fracture would be dissimilar to the homogeneous surrounding rock without fracture in damage model, and original fissure have a larger effect on creep damage of surrounding rock.

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