An improved numerical approach in surrounding rock incorporating rockbolt effectiveness and seepage force

2018 ◽  
Vol 13 (3) ◽  
pp. 707-727 ◽  
Author(s):  
Jinfeng Zou ◽  
Kaifu Chen ◽  
Qiujing Pan
Keyword(s):  
Numerical Approach ◽  
Surrounding Rock ◽  
Seepage Force

scholarly journals An Improved Stress and Strain Increment Approaches for Circular Tunnel in Strain-Softening Surrounding Rock Considering Seepage Force

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Ling Wang ◽  
Jin-feng Zou ◽  
Yu-ming Sheng
Keyword(s):  
Rock Mass ◽  
Plastic Zone ◽  
Radial Displacement ◽  
Axisymmetric Problem ◽  
Strain Softening ◽  
Strain Increment ◽  
Surrounding Rock ◽  
Stress And Strain ◽  
Seepage Force ◽  
Circular Tunnel

Considering the effect of seepage force, a dimensionless approach was introduced to improve the stress and strain increment approach on the stresses and radial displacement around a circular tunnel excavated in a strain-softening generalized Hoek–Brown or Mohr–Coulomb rock mass. The circular tunnel can be simplified as axisymmetric problem, and the plastic zone was divided into a finite number of concentric rings which satisfy the equilibrium and compatibility equations. Increments of stresses and strains for each ring were obtained by solving the equilibrium and compatibility equations. Then, the stresses and displacements in softening zone can be calculated. The correctness and reliability of the proposed approach were performed by the existing solutions.

scholarly journals Theoretical Analysis of Safety Thickness of the Water-Resistant Rock Mass of Karst Tunnel Face Taking Into Account Seepage Effect

2021 ◽  
Author(s):  
Jiaqi GUO ◽  
Wenlong Wu ◽  
Xiliang Liu ◽  
Xin Huang ◽  
Zhengguo Zhu
Keyword(s):  
Rock Mass ◽  
Influencing Factors ◽  
Water Pressure ◽  
Water Inrush ◽  
Surrounding Rock ◽  
Karst Water ◽  
Seepage Force ◽  
Karst Tunnel ◽  
Tunnel Face ◽  
Safety Thickness

Abstract This paper took into account the adverse influence of the karst water seepage effect on the water-resistant rock mass. Based on the upper-bound theorem of limit analysis and the Hoek-Brown failure criterion, through a series of formula derivation, the expression of critical safety thickness of water-resistant rock mass of karst tunnel face was finally obtained. The paper carried out a feasibility analysis, an analysis of influencing factors and a comparative analysis with previous related research achievements of this method. The results showed that: (1) With the decrease of surrounding rock grade, the safety thickness of water-resistant rock mass gradually increased, and the safety thickness of surrounding rock at all grades remained within a reasonable range. (2) The safety thickness decreased as the compressive strength, the tensile strength and parameter A increased, and it increased as the karst water pressure, the tunnel excavation height, and parameter B increased. (3) The change trend of the safety thickness with the influencing factors was completely consistent under the two conditions of considering and without the seepage effect, and the safety thickness with considering the seepage force was greater than that without considering the seepage force. Taking the Yunwushan tunnel of Yiwan railway as an example, the critical safety thickness of the water-resistant rock mass was calculated and the calculated value was in good coincidence with the safety thickness adopted in the actual project. The research results are of great significance to prevent the occurrence of high pressure filling karst geological disasters such as water inrush in tunnels.

scholarly journals Simulating the Formation of Blasting-Excavation-Induced Zonal Integration in Deep Tunnels with an Elastoplastic Damage Model

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Qiang Gao ◽  
Chuanxiao Liu ◽  
Jian Zhang ◽  
Guangtan Cheng
Keyword(s):  
Coupling Effect ◽  
Damage Model ◽  
Morphological Characteristics ◽  
Numerical Approach ◽  
Surrounding Rock ◽  
Strain Gradient Theory ◽  
Zonal Disintegration ◽  
Gradient Theory ◽  
Blasting Excavation ◽  
Elastoplastic Damage

More deep tunneling projects will be constructed due to the increasing demand of underground energy and resource. The zonal disintegration phenomena are frequently encountered with the surrounding rock of deep tunnels. To explain the mechanisms underlying the formation of zonal disintegration, an elastoplastic damage model and failure criterion are proposed in this study based on the strain gradient theory and the damage property of rock mass. A coupling calculation subroutine is thereafter developed by the ABAQUS code. The dynamic formation and development regularity of zonal disintegration in the deep tunnel are simulated by this subroutine. The radial displacement, radial stress, and tangential stress show the oscillated variation of peaks and troughs alternately. The coupling effect of the blasting load and the initial geostress transient unloading leads to the variation of alternation oscillation in the surrounding rock stress field, which is an important reason for the zonal disintegration of the surrounding rock. The morphological characteristics of fractured zones and nonfractured zones obtained from numerical simulations are in good agreement with the results from the in situ observations, which confirm the correctness and feasibility of the damage and numerical approach. The method proposed in the current study can be utilized to provide a basis for the prediction and supporting design of fractured modes.

THERMAL MODELING OF ICE-PACKS IN COOLING VESTS FOR EXTREME HOT CLIMATIC CONDITION: A NUMERICAL APPROACH

2018 ◽  
Author(s):  
Vedant Bhuyar ◽  
Shiv Ram Suthar ◽  
Mohit Vijay ◽  
Prodyut R. Chakraborty
Keyword(s):  
Climatic Condition ◽  
Thermal Modeling ◽  
Numerical Approach

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

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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