Research about the Rationality of Neighborhood Tunnel Spacing

2012 ◽  
Vol 594-597 ◽  
pp. 1280-1284
Author(s):  
Bo Wen Yang ◽  
Shuang Suo Yang
Keyword(s):  
Mathematical Model ◽  
Principal Stress ◽  
Safety Factor ◽  
Friction Angle ◽  
Surrounding Rock ◽  
Analysis Method ◽  
Rock Stress ◽  
Rock Stability ◽  
Simulation Based ◽  
Surrounding Rock Stress

Analysis of the surrounding rock stress distribution of neighborhood tunnel by using numerical simulation. Based on Cullen-Moore Theory, build a mathematical model of 1st principal stress σ1, 2nd principal stress σ2, internal friction angle φ, and cohesion c, then, make a expression of tunnel spacing safety factor A. Analysis a real tunnel project and evaluate its surrounding rock stability with safety factor A as the index. Propose an analysis method of judging the rationality of tunnel spacing.

scholarly journals Study on Stability of Round Tunnel Surrounding Rock

2018 ◽  
Vol 175 ◽  
pp. 04016
Author(s):  
NIU Yan ◽  
Ji Yafei ◽  
Wang Zhao
Keyword(s):  
Evaluation Criteria ◽  
Surrounding Rock ◽  
Rock Stress ◽  
Stress Release ◽  
Circular Tunnel ◽  
Tunnel Excavation ◽  
Finite Element Software ◽  
Rock Stability ◽  
The Stability ◽  
Surrounding Rock Stress

Tunnel excavation will lead to the immediate surrounding rock unloading caused by the surrounding rock stress release, the stability of the surrounding rock have a certain impact. In this paper, finite element software ANSYS and finite difference software FLAC3D are used to simulate the excavation and lining process of circular tunnel. The influence of excavation on the rock stability around circular tunnel is analyzed, and the effect of applying lining on the stability of surrounding rock is analyzed. Evaluation criteria selection hole displacement, stress and plastic area of three factors.

Calculation Methods of Surrounding Rock Pressure for Small Clear Spacing Shallow Unsymmetrically Loading Tunnel

2012 ◽  
Vol 430-432 ◽  
pp. 1464-1467
Author(s):  
Li Chuan Wang ◽  
Li Min Peng ◽  
Dong Wei Zhou
Keyword(s):  
Rock Pressure ◽  
Failure Modes ◽  
Surrounding Rock ◽  
Analysis Method ◽  
Calculation Methods ◽  
Rock Stress ◽  
Basic Assumptions ◽  
Surrounding Rock Pressure ◽  
Limit Analysis Method ◽  
Surrounding Rock Stress

In the process of construction, it is essential to determine the surrounding rock pressure, which needs to propose the simulation model according to relevant theory, and calculate and analyze the surrounding rock stress, to guarantee the safety of the tunnel construction and operation. However, this has been no perfect calculation theory and formula for surrounding rock stress to unsymmetrically loading tunnel (ULT). The constructed method of failure modes on the shallow ULT are proposed, together with the failure mode for the shallow unsymmetrically load single tunnel, based on the basic assumptions and basic theories of limit analysis method (LAM).

Field Monitoring of Surrounding Rock Stress in Tunnel Construction

2012 ◽  
Vol 170-173 ◽  
pp. 1735-1739
Author(s):  
Ying Na Dong ◽  
Qiang Huang
Keyword(s):  
Spatial Effect ◽  
Field Monitoring ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Rock Stress ◽  
Vibrating Wire ◽  
Stress Variation ◽  
Stress Changes ◽  
Tunnel Diameter ◽  
Surrounding Rock Stress

The surrounding rock stress field monitor has been done in excavation by vibrating wire transducer. The field monitoring data are compared with numerical simulation results. The result shows: Vibrating wire transducer can record the stress variation of surrounding rock and support. Surrounding rock stress changes violently at every excavation step, such as lower bench excavation, the stress variation is mainly controlled by the spatial effect. When the distance from excavation face to the monitoring section is more than a tunnel diameter, the rock stress variation is mainly affected by time and it is relatively smooth and continuous.

scholarly journals An Experimental Research on Surrounding Rock Unloading during Solid Coal Roadway Excavation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hongjun Guo ◽  
Ming Ji ◽  
Dapeng Liu ◽  
Mengxi Liu ◽  
Gaofeng Li ◽  
...  
Keyword(s):  
Energy Storage ◽  
Deformation Energy ◽  
Surrounding Rock ◽  
Dissipated Energy ◽  
Rock Stress ◽  
Deformation And Failure ◽  
Coal Roadway ◽  
Solid Coal ◽  
Unloading Rate ◽  
Surrounding Rock Stress

In order to further explore the deformation and failure essence of the deep coal body, based on the characteristics of surrounding rock stress adjustment before and after solid coal roadway excavation, an experiment of unloading confining pressure and loading axial pressure of the coal body was designed and conducted in this study. Based on test results, the failure mechanics and energy characteristics of the coal body were analyzed through experiments. Rapid unloading is considered a key factor contributing to lateral deformation and expansion failure, which exacerbates the deterioration of coal body and reduces the deformation energy storage capacity of coal. On the other hand, the larger loading rate tends to shorten the accumulation time of microcracks and cause damage to the coal body, resulting in strengthening the coal body and improving energy storage. Under the circumstance that the coal body is destroyed, the conversion rates of the internal deformation energy and dissipated energy are more significantly affected by unloading rate. The increasing unloading rate and rapid decreases in the conversion rate of deformation energy make the coal body more vulnerable to damage. Under the same stress conditions, the excavation unloading is more likely to deform, destroy, or even throw the coal than the experiment unloading. In order to reduce or avoid the occurrence of deep roadway excavation accidents, the understanding of the excavation unloading including possible influencing factors and the monitoring of the surrounding rock stress and energy during the excavation disturbance should be strengthened. It can be used as the basis for studying the mechanism of deformation and failure of coal and rock and dynamic disasters in deep mines, as well as the prediction, early warning, prevention, and control of related dynamic disasters.

scholarly journals Stress Evolution Law of Surrounding Rock with Gob-Side Entry Retaining by Roof Cutting and Pressure Release in Composite Roof

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yong Zhang ◽  
Huichen Xu ◽  
Peng Song ◽  
Xiaoming Sun ◽  
Manchao He ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Surrounding Rock ◽  
Rock Stress ◽  
Dynamic Adjustment ◽  
Pressure Relief ◽  
Middle Point ◽  
Pressure Release ◽  
Whole Process ◽  
Working Face ◽  
Surrounding Rock Stress

The stress concentration of gob-side entry surrounding rock is a hot topic in coal mining. In this paper, through theoretical analysis and numerical simulation, the pressure relief mechanism of the gob-side entry retaining by roof cutting and pressure release (RCPR) and the spatiotemporal development law of surrounding rock stress of the gob-side entry were analyzed. The studies showed that the gob-side entry retaining by RCPR shortened the length of the lateral cantilever by directional roof cutting, which weakened the stress level of the gob-side entry. In the meantime, the goaf gangues could play a good filling role by using their breaking and swelling characteristics under the action of gangue-blocking supports and further optimized the stress environment along the roadway. Field industrial tests verified that the gob-side entry retaining by RCPR had a significant effect on pressure relief, and the surrounding rock stress and deformation tended to stabilize after about 160 m of lagging working face. Numerical analysis reproduced the whole process of “mining-retention-using” of roof cutting roadway and revealed that surrounding rocks were always in the zone of relative stress reduction during the whole process. The peak value of mining-induced lateral stress was about 10 m away from the middle point of the gob-side entry. The change of surrounding rock stress could be divided into three stages: significant increase, dynamic adjustment, and stable stage. However, during the second mining, the stress connected zone would appear on the leading working face, and the stress concentration in this zone was significant. Based on the above analysis, we concluded that the new technology could be applied to the medium-thickness coal seam in the composite roof.

Grey Correlation Analysis on the Sensitive Factors of Plastic Zone Extension of Surrounding Rock

2013 ◽  
Vol 438-439 ◽  
pp. 1210-1216
Author(s):  
Xuan Rong Zheng
Keyword(s):  
Correlation Analysis ◽  
Plastic Zone ◽  
Deformation Modulus ◽  
Friction Angle ◽  
Surrounding Rock ◽  
Unit Weight ◽  
Analysis Method ◽  
Grey Correlation ◽  
Grey Correlation Analysis ◽  
Ground Stress

As lack of explicit analysis method on the sequence of many factors influencing the plastic zone extension of surrounding rock, the grey correlation analysis method is adopted to study the relationship between the plastic zone extension radius Rp and the six factors such as cohesive c, internal friction angle φ, deformation modulus E, unit weight γ, initial ground stress σ and the radius of chamber r. By dealing with dimensionless, the corresponding sequences composed with the sensitive factors as sub-sequence and the plastic zone extension radius as mother sequence are obtained. The gray correlation analysis model of sensitive factors which evaluates the results with grey correlation degree is built by the methods of dimensionless and extreme difference variation. Then, an engineering example is analyzed with grey correlation. Based on the analysis results, the sorting of sensitive factors is φ > σ > c > r > E > γ. It implies that the influences of internal friction angle φ and initial ground stress σ are the most prominent, and the sensitivities of deformation modulus E and unit weight γ are lowest. These are in good agreement with the analytical formula of classical theory, and can be used in guiding the further optimization and improvement of the analytical expression of the plastic zone extension radius Rp of surrounding rock.

scholarly journals Study on strength parameters of rock mass with stochastic combination discontinuities and their application in a tunnel in China

2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878208
Author(s):  
Jihong Wei ◽  
Jin Liu ◽  
Zezhuo Song ◽  
Yulong Zhu ◽  
Yuxia Bai
Keyword(s):  
Rock Mass ◽  
Numerical Test ◽  
Surrounding Rock ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Test Case ◽  
Analysis Method ◽  
Circular Tunnel ◽  
Rock Stability ◽  
Discontinuous Deformation

The rock mass has special properties, such as inhomogeneity, anisotropy, discontinuity, and nonelastic, due to various internal or external stress in the process of its formation. In this study, similar materials are considered to simulate the rock mass and analyze the failure law using laboratory tri-axial tests based on the similarity principle. The rock mass and discontinuity are constituted in the process of model construction by considering the influence of the orientation, spacing, and number of discontinuity, respectively. Then, the influences of the orientation, spacing, number of discontinuity, and the combination of different discontinuous strength on rupture mechanism of the rock mass are analyzed by considering lots of numerical test schemes using the discontinuous deformation analysis method. Finally, considering water conveyance tunnel in Jurong Pumped Storage Power Station in China as a test case, the tunnel stability under different discontinuities combination is analyzed using discontinuous deformation analysis method. The influence of the optimal tunnel axis and tunnel shape on the stability of surrounding rock is studied by comparative analysis of surrounding rock stability under different tunnel axis and tunnel shapes. The stress concentration in case of the circular tunnel with corner is somehow less than that of the rectangular one.

Numerical Analysis of Deeply Buried Small Net Distance Tunnels on Rock Stability under Different Construction and Methods

2013 ◽  
Vol 838-841 ◽  
pp. 1346-1351
Author(s):  
Yong Ding Tian ◽  
Cong Cai ◽  
Jia Peng ◽  
Jin Hua Wu ◽  
Jia Qi Zhang
Keyword(s):  
Lateral Wall ◽  
Internal Force ◽  
Complex Stress ◽  
Surrounding Rock ◽  
System Structure ◽  
Finite Element Software ◽  
Rock Stability ◽  
Before And After ◽  
Full Face ◽  
Surrounding Rock Stress

Based on the background of a highway, for tunnels with small spacing of complex stress condition, adopt various construction schemes for numerical simulation using Midas Gts finite element software under the condition of deep-buried small net distance tunnel. Use full-face excavation method, benching tunneling construction method and both side heading method to compare surrounding rock stress, surrounding rock deformation, internal force of bolt and shotcrete support system structure, lateral-wall displacement and stability of surrounding rock. Analyse displacement and stress change laws before and after the excavation of tunnel surrounding rock and supporting structure under different schemes.

Reinforced Techniques Analysis of Goaf-Side Entry at Isolated Island Coal Face Based on FLAC Numerical Simulation

2012 ◽  
Vol 605-607 ◽  
pp. 210-214 ◽  
Author(s):  
Wen Hua Zha
Keyword(s):  
Surrounding Rock ◽  
Good Effect ◽  
Control Problems ◽  
Rock Stress ◽  
Coal Face ◽  
The Third ◽  
Result Show ◽  
Surrounding Rock Control ◽  
Stress And Deformation ◽  
Surrounding Rock Stress

According to control problems of surrounding rock at isolated island coal face, taking isolated island coal 1251（3）face ventilation tunnel of PanSan mine as engineering background, this paper puts forward three reinforcement schemes based on the idea of turning later recovery to former reinforcement. Simulation has been done on the character of surrounding rock stress and deformation distribution and supporting structure force of three different schemes by FLAC3D. Finally optimal scheme is the third scheme. The application result show that anchor-net-cable support combined with anchor grouting support has got a good effect. The large deformation of surrounding rock is controlled efficiently and tunnel surrounding rock stable is guaranteed. The study provides a basis for goaf-side entry surrounding rock control under similar conditions.

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