scholarly journals Corrigendum to “Study on the Vibration Effect of Short Footage Blasting Load on Surrounding Rock-Support Structure of Tunnel”

2021 ◽  
Vol 2021 ◽  
pp. 1-2
Author(s):  
Chunquan Dai ◽  
Hongtao Sui ◽  
Chao Ma
Keyword(s):  
Surrounding Rock ◽  
Rock Support ◽  
Support Structure ◽  
Vibration Effect ◽  
Blasting Load

scholarly journals Study on the Vibration Effect of Short Footage Blasting Load on Surrounding Rock-Support Structure of Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Chunquan Dai ◽  
Hongtao Sui ◽  
Chao Ma
Keyword(s):  
Surrounding Rock ◽  
Vibration Velocity ◽  
Rock Support ◽  
Support Structure ◽  
Measuring Point ◽  
Supporting Structure ◽  
Finite Element Software ◽  
Excavation Process ◽  
Blasting Load ◽  
Vibration Damage

In the excavation process of a drilling and blasting tunnel, it takes multiple blasting excavations to form, so it is inevitable to produce multiple blasting impact loads, which will cause certain vibration damage to the surrounding rock-support structure. To solve this problem, based on the attenuation formula of blasting vibration wave and considering the cumulative effect of short footage blasting load, the radial displacement formula of surrounding rock particles is derived, and the analytical solution of vibration velocity field is obtained by using the method of separating variables. Then, taking Cuobuling station of Qingdao Metro as the engineering background, the finite element software is used to simulate the tunnel excavation process under the action of short footage multiple blasting. The vibration damage impact of multiple blasting loads on the surrounding rock-supporting structure is analyzed from the accumulated displacement value and vibration velocity cumulative value of the excavation tunnel. The results show that the damage accumulation effect is produced in the surrounding rock of each section during the blasting construction, among which the accumulation is the largest at the arch bottom. With the increase of blasting times, the damage of the surrounding rock is still accumulating gradually. Compared with the first blasting, the peak value of vibration velocity of the second blasting increased by 114%, and with the increase of blasting times, the variation trend of maximum vibration velocity of the measuring point showed an upward trend, but the subsequent vibration acceleration decreased. Under the condition of grade V surrounding rock, when the thickness of the concrete spray layer is 350 mm, the maximum displacement cumulative value of each measuring point in profile 1-1 is reduced by about 50.4% compared with that without support. According to the displacement nephogram of the concrete spray layer, the displacement of the concrete spray layer accumulates after three times of blasting, which affects the stability of the supporting structure. Finally, an example analysis is carried out and compared with the analytical model results to verify the accuracy of the mechanical model.

A New Criterion for Stability Analysis of Tunnel Surrounding Rock-Support Structure Based on the Convergence-Confinement Method

2012 ◽  
Vol 629 ◽  
pp. 427-432
Author(s):  
Yong Kang ◽  
Bo Long Chai ◽  
Xiao Chuan Wang ◽  
Deng Li
Keyword(s):  
Stability Analysis ◽  
Surrounding Rock ◽  
Geological Condition ◽  
Rock Support ◽  
Support Structure ◽  
Weak Zone ◽  
Deformation And Failure ◽  
True Value ◽  
The Stability ◽  
Ultimate Displacement

In the decision making of tunnel excavation and support scheme, stability analysis of surrounding rock-support structure is an essential link. Especially in fractured weak zone under complex geological condition, accurately measuring the deformation of support structure has an important significance for fast and safe construction. Based on the application of convergence confinement principle in judging tunnel deformation, this paper presented a new idea of using the ultimate displacement of tunnel initial support to analyze the stability of tunnel surrounding rock-support structure. Then, with a full investigation on the deformation and failure characteristics of highway tunnel surrounding rock at fractured weak zone, the ultimate displacement was got by using methods of numerical calculation and site monitoring measurement. Finally, the stability analysis of support structure in Zhongxing Tunnel was done. It can be arrived that there is a certain gap between true value u and measured value um of surrounding rock deformation. If the measuring points are installed after three excavation cycle, u is approximately equal to 1.6 um. then, based on the analysis of numerical simulation results and monitoring data of Zhongxing Tunnel, the paper indicated that the top and spring of arch are risk regions, reserved deformation of fractured weak zone is not enough, it should be adjusted from 10cm to 20cm.

scholarly journals Investigation of Deep Shaft-Surrounding Rock Support Technology Based on a Post-Peak Strain-Softening Model of Rock Mass

2021 ◽  
Vol 12 (1) ◽  
pp. 253
Author(s):  
Jianjun Zhang ◽  
Yang Wang ◽  
Baicong Yao ◽  
Dongxu Chen ◽  
Chuang Sun ◽  
...  
Keyword(s):  
Rock Mass ◽  
Strain Softening ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Peak Strain ◽  
Rock Support ◽  
Support Structure ◽  
The Stability ◽  
Surrounding Rock Deformation

To control the large deformation that occurs in deep shaft-surrounding rock, the post-peak strain-softening characteristics of deep jointed rock mass are discussed in detail. An equivalent post-peak strain-softening model of jointed rock mass is established based on continuum theory and the geological strength index surrounding rock grading system, and numerical simulations are performed using FLAC3D software. The convergence-constraint method is used to analyze the rock support structure interaction mechanism. A composiste support technique is proposed in combination with actual field breakage conditions. During the initial support stage, high-strength anchors are used to release the rock stress, and high-stiffness secondary support is provided by well rings and poured concrete. This support technology is applied in the accessory well of a coal mine in Niaoshan, Heilongjiang, China. The stability of the surrounding rock support structure is calculated and analyzed by comparing the ideal elastic-plastic model and equivalent jointed rock mass strain-softening model. The results show that a support structure designed based on the ideal elastic-plastic model cannot meet the stability requirements of the surrounding rock and that radial deformation of the surrounding rock reaches 300 mm. The support structure designed based on the equivalent joint strain-softening model has a convergence rate of surrounding rock deformation of less than 1 mm/d after 35 days of application. The surrounding rock deformation is finally controlled at 140 mm, indicating successful application of the support technology.

scholarly journals Geometrical Tests of Powered Roof Support Positioning in a Longwall Complex

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Dawid SZURGACZ ◽  
Sergey ZHIRONKIN ◽  
Konrad TRZOP ◽  
Stefan VÖTH ◽  
Leszek SOBIK ◽  
...  
Keyword(s):  
Rock Mass ◽  
Research Team ◽  
Surrounding Rock ◽  
Support Structure ◽  
Roof Support

A powered roof support protects people and equipment in the longwall from potential dangerposed by the surrounding rock mass. The study to determine the position of the powered roof supportwas conducted in an active longwall. The research team made measurements of the geometric height ofthe powered roof support structure located in the longwall complex. The main objective of this studywas to determine the position of the powered roof support in actual underground conditions. Theanalysis of the results provided data on whether the assumed height of the longwall was maintainedduring operation of the complex.

Analysis of the dynamic influence of the input blasting load on the tunnel surrounding rock

2015 ◽  
Vol 19 (sup8) ◽  
pp. S8-923-S8-930
Author(s):  
C. Z. Yang ◽  
Z. J. Yu ◽  
S. F. Wang
Keyword(s):  
Surrounding Rock ◽  
Blasting Load

scholarly journals Analysis on the Influence Degree of Deformation Control Factors of Deep-Buried Roadway’s Fractured Surrounding Rock Using Orthogonal Design

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ke Li ◽  
Weijian Yu ◽  
Youlin Xu ◽  
Ze Zhou ◽  
Mengtang Xu ◽  
...  
Keyword(s):  
Orthogonal Design ◽  
Surrounding Rock ◽  
Row Spacing ◽  
Structure Parameters ◽  
Support Structure ◽  
Support Design ◽  
Multi Index ◽  
Cable Length ◽  
Control Factors ◽  
Influence Degree

It is a complex issue to select the support structure parameters for a deep-buried roadway with fractured surrounding rock; especially when the support structure parameters need to be adjusted, the influence degree of support structure parameters on roadway deformation needs to be determined. The deformation of deep-buried roadway’s fractured surrounding rock development was investigated using multi-index orthoplan in this paper. According to the coal mine field investigation, support structure’s failure often occurs, and some need to be repaired many times. Through the roadway surrounding rock drilling, it was found that the stress of the surrounding rock was relieved, resulting in the cavity and separation of the stratum layer. The two sidewalls’ development and roof fractures are mainly tangential, and the original rock state appears only beyond 6.3∼8.2 m. The length of bolts, the row distance between bolts, the length of cables, and the row distance of U-shaped steel were selected as control factors in the multi-index orthogonal design, and roadway’s deformation values were taken as the test indexes. According to the orthoplan, nine numerical simulation schemes were designed, and FLAC3D was used for establishment. The range analysis method was used to analyze the test results. The results show that the control factors’ influence order on the total deformation of the roadway is as follows: row spacing between U-shaped steel > bolt length > cable length > row spacing between bolts, the influence order on the deformation of the roadway floor is as follows: row spacing between U-shaped steel > row spacing between bolts > bolt length > cable length, same as the left sidewall and right sidewall, and the influence order on the roadway roof’s deformation is as follows: row spacing between U-shaped steel > bolt length = cable length > row spacing between bolts, which provide a reference for the support design of deep-buried roadways with fractured surrounding rock, especially the adjustment of the supporting structure.

scholarly journals Analysis of Plastic Zone and Pressure Variance Features of Surrounding Rock of High-Altitude Macker Tunnel: A Case Study in Jiangluling Macker Tunnel in Qinghai

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaojun Ma ◽  
Hongyan Guo ◽  
Juyi Hu ◽  
Shuang Cai ◽  
Liang Cheng ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Structural Design ◽  
Measurement Data ◽  
Surrounding Rock ◽  
Analysis Method ◽  
Support Structure ◽  
Tunnel Support ◽  
Influence Radius ◽  
Design Of Tunnel Support

Due to the special mechanical properties of macker rock, problems may be caused easily if the pressure of the surrounding rock calculated from the standard empirical equation is used in the structural design of tunnel support, such as obviously insufficient bearing capacity of the support structure, large deformation, and collapse. Taking the Jiangluling Macker Tunnel in Gonghe-Yushu Highway as an example, the distribution pattern of plastic zone of the surrounding rock and the calculation method and reasonable values of pressure of the surrounding rock are studied in this paper, by means of theoretical analysis, numerical computation, and field measurement data. The results show that the elastic-plastic analysis method is suitable for the pressure of the surrounding rock of macker tunnel. The influence radius of the plastic zone of the surrounding rock can be 32 m, and the lateral pressure of the surrounding rock of the tunnel is equivalent to the vertical pressure. In the absence of test conditions and measured data, the pressure of the surrounding rock can be approximately 0.83 MPa for the purpose of design of tunnel support structure. This conclusion provides technical support for projects in similar conditions.

scholarly journals The Plastic Zone of Tunnel Surrounding Rock under Unequal Stress in Two Directions Based on the Unified Strength Theory

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zongshan Zou ◽  
Jun Yang ◽  
Zhongming Wang ◽  
Hongyan Liu
Keyword(s):  
Plastic Zone ◽  
Principal Stress ◽  
Interaction Mechanism ◽  
Strength Criterion ◽  
Intermediate Principal Stress ◽  
Surrounding Rock ◽  
Elastic Displacement ◽  
Strength Theory ◽  
Support Structure ◽  
Unified Strength Theory

For the deficiencies that the existing calculation theory for the Plastic Zone of Tunnel Surrounding Rock (PZTSR) does not consider the effect of the intermediate principal stress σ2 and interaction between the surrounding rock and support structure on the PZTSR under unequal stress, the Unified Strength Theory (UST) for the rock is adopted to replace the often used Mohr-Coulomb (M-C) strength criterion to consider the effect of σ2 on the PZTSR. Meanwhile, the interaction mechanism between the surrounding rock and support structure is also considered in the proposed model. Finally, the effect of the initial elastic displacement of the surrounding rock, stiffness of the support structure, and the coefficient b of the intermediate principal stress on the plastic zone is discussed. The results show that the PZTSR will increase nonlinearly with increasing the initial elastic displacement of the surrounding rock, and when it increases to a certain value, its increase extent will be much obvious. With increasing the stiffness of the support structure, the PZTSR will gradually decrease nonlinearly, but the decrease extent is not very much. With increasing b, the PZTSR will decrease; namely, σ2 can improve the stress condition of the surrounding rock and reduce the PZTSR.

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