Computer Aided Understanding for Interaction between Stratified Slope and Bolt

2012 ◽  
Vol 433-440 ◽  
pp. 3152-3157
Author(s):  
Lian Jun Zhou ◽  
Xiao Min Li
Keyword(s):  
Rock Mass ◽  
Rock Slope ◽  
Deformation Analysis ◽  
Planar Geometry ◽  
Analysis Method ◽  
Rock Masses ◽  
Rock Bolts ◽  
Layered Rock ◽  
Stratified Rock ◽  
Primary Support

Slope excavations are often constructed in stratified host rock masses in practice. The stratification in a rock mass is generally characterised by its planar geometry and persistence. The mechanical properties of the joints dictate both the deformation and strength characteristics of the stratified rock mass. Thus, it is imperative that the influence of the joints be incorporated in any type of load-deformation analysis of slope excavations in layered rock masses. Rock bolts have been widely used as the primary support system to stabilize the rock masses of slope. In general, rock bolts reinforce rock masses through restraining the deformation within rock masses and reduces the yield region around the excavation boundary. In order to improve bolting design, it is necessary to have a good understanding of the behaviour of rock bolts in deformed rock masses. In the present paper, the numerical analysis method is adopted to built the three springs bolt element; then the excavation in the stratified rock slope is simulated to improve the understanding of the slope deformation and bolt mechanical characteristic.

scholarly journals Primary Investigation on Equivalent Anchoring Method of Jointed Rock Mass Tunnel and Its Engineering Application

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Min Gao ◽  
Shanpo Jia
Keyword(s):  
Rock Mass ◽  
Three Dimensional ◽  
Engineering Application ◽  
Friction Angle ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Rock Masses ◽  
Reinforcement Effect ◽  
Rock Bolts

Rock bolts, one of the main support structures of the tunnel, can improve the stress state and mechanical properties of the surrounding rocks. The rock bolts are simulated by bar or beam elements in present numerical calculations for most 2D tunnel models. However, the methods of simulating rock bolt in three-dimensional models are rarely studied. Moreover, there are too many rock bolts in the long-span tunnel, which are hardly applied in the 3D numerical model. Therefore, an equivalent anchoring method for bolted rock masses needs to be further investigated. First, the jointed material model is modified to simulate the anisotropic properties of surrounding rock masses. Then, based on the theoretical analysis of rock bolts in reinforcing mechanical properties of the surrounding rock masses, the equivalent anchoring method of the jointed rock mass tunnel is numerically studied. The equivalent anchoring method is applied to the stability analysis of a diversion tunnel in Western China. From the calculation results, it could be found that the reinforcement effect of rock bolts could be equivalently simulated by increasing the mechanical parameter value of surrounding rocks. For the jointed rock mass tunnel, the cohesion and internal friction angle of the surrounding rocks are improved as 1.7 times and 1.2 times of the initial value, which can simulate the reinforcement effect of rock bolts. Comparing with analytical results, the improved internal friction angle is nearly consistent with analytical result. The reinforcement effect of rock bolts is simulated obviously when the mechanical parameters of surrounding rocks are increased simultaneously. The engineering application shows that the equivalent anchoring method can reasonably simulate the effect of rock bolts, which can provide reference for stability analysis of three-dimensional tunnel simulations.

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.

scholarly journals A Thermal Effect Model for the Impact of Vertical Groundwater Migration on Temperature Distribution of Layered Rock Mass and Its Application

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1285
Author(s):  
Haifeng Lu ◽  
Yuan Zhang ◽  
Guifang Zhang ◽  
Manman Zhang
Keyword(s):  
Thermal Conductivity ◽  
Rock Mass ◽  
Temperature Distribution ◽  
Temperature Curve ◽  
Geothermal Water ◽  
Layered Rock ◽  
Effect Model ◽  
Layered Rock Mass ◽  
Stratified Rock ◽  
Stratified Rock Mass

On the basis of the one-dimensional heat conduction–convection equation, a thermal effect model for vertical groundwater migration in the stratified rock mass was established, the equations for temperature distribution in layered strata were deduced, and the impacts of the vertical seepage velocity of groundwater and the thermal conductivity of surrounding rocks on the temperature field distribution in layered strata were analyzed. The proposed model was employed to identify the thermal convection and conduction regions at two temperature-measuring boreholes in coal mines, and the vertical migration velocity of groundwater was obtained through reverse calculation. The results show that the vertical temperature distribution of the layered rock mass is subject to the migration of the geothermal water; the temperature curve of the layered formation is convex when the geothermal water travels upward, but concave when the water moves downward. The temperature distribution in the stratified rock mass is also subject to the thermal conductivity of the rock mass; greater thermal conductivity of the rock mass leads to a larger temperature difference among regions of the rock mass, while weaker thermal conductivity results in a smaller temperature difference. A greater velocity of the vertical migration of geothermal water within the surrounding rock leads to a larger curvature of the temperature curve. The model was applied to a study case, which showed that the model could appropriately describe the variation pattern of the ground temperature in the stratified rock mass, and a comparison between the modeling result and the measured ground temperature distribution revealed a high goodness of fit of the model with the actual situation.

scholarly journals Stabilization of Deep Roadways in Weak Rocks Using the System of Two-level Rock Bolts

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Tuan Minh TRAN ◽  
Ngoc Thai DO ◽  
Trung Thanh DANG ◽  
Duyen Phong NGUYEN ◽  
Trong Hung VO
Keyword(s):  
Rock Mass ◽  
Surrounding Rock ◽  
Rock Bolts ◽  
Weak Rocks ◽  
Total Displacement ◽  
Cable Bolts ◽  
Rock Mass Deformation ◽  
Technical Solutions ◽  
Primary Support ◽  
Mass Deformation

Large rock mass deformation around deep roadways in the weak rocks was a significantproblem in mining activities in Vietnam and other countries. The excavation of roadways leads to highreleasing stress, which exceeds the peak strength of spalling surrounding rock and causes it to enter thepost-failure stage. Tensile failures then initiate and develop around the roadways, which causes thefragmentation, dilation, and separation of surrounding rock. The capacity of the primary support systemis low, which results in a severe contraction in the whole section of roadways, which requires findingsolutions to prevent the deformation of rock mass around roadways and technical solutions fromstabilizing for deep roadways. To stability analysis of roadways can be applied analytical, experimental,semi-experimental, and numerical methods. This paper introduces the prevention mechanism of largedeformation of rock mass around roadways using 2-level rock bolts. The research results show that usingthe system of two-level rock bolts can reduce the values of tensile stress on the boundary of roadwaysrange from 10 to 15% compared with only one. The importance of the total displacement of rock mass onthe boundary of roadways will be reduced from 3.47 to 13.85% using six long cable bolts.

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