scholarly journals An Estimation Method of In-situ Rock Masses by Characteristic of Electric Resistivity for Jointed Rock Mass Model

2006 ◽  
Vol 55 (5) ◽  
pp. 458-463
Author(s):  
Makoto NAKAMURA ◽  
Harushige KUSUMI
Keyword(s):  
Rock Mass ◽  
Estimation Method ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Electric Resistivity ◽  
Rock Masses ◽  
Mass Model

Analysis of TBM Tunnel Behavior in Jointed Rock Mass

2011 ◽  
Vol 90-93 ◽  
pp. 2033-2036 ◽  
Author(s):  
Jin Shan Sun ◽  
Hong Jun Guo ◽  
Wen Bo Lu ◽  
Qing Hui Jiang
Keyword(s):  
Rock Mass ◽  
Numerical Models ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Jointed Rock Mass ◽  
Joint Orientation ◽  
Joint Spacing ◽  
Factors Affecting ◽  
Dip Angle

The factors affecting the TBM tunnel behavior in jointed rock mass is investigated. In the numerical models the concrete segment lining of TBM tunnel is concerned, which is simulated as a tube neglecting the segment joint. And the TBM tunnel construction process is simulate considering the excavation and installing of the segment linings. Some cases are analyzed with different joint orientation, joint spacing, joint strength and tunnel depth. The results show that the shape and areas of loosing zones of the tunnel are influenced by the parameters of joint sets and in-situ stress significantly, such as dip angle, spacing, strength, and the in-situ stress statement. And the stress and deformation of the tunnel lining are influenced by the parameters of joint sets and in-situ stress, too.

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.

A New Method to Determining the Strength Parameters of Fractured Rock Mass

2014 ◽  
Vol 898 ◽  
pp. 378-382
Author(s):  
Yun Hua Guo ◽  
Wei Shen Zhu
Keyword(s):  
Rock Mass ◽  
Mechanical Response ◽  
Fractured Rock ◽  
Fracture Network ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Constitutive Relationship ◽  
Hydropower Station ◽  
Rock Masses ◽  
Fractured Rock Mass

A Hydropower Station is located in the middle reach of the Dadu River in southwest China. The natural slope angles are generally 40°~65° and the relative elevation drop is more than 600m. Complex different fractures such as faults, dykes and dense fracture zones due to unloading are developed. Many abutment slopes were formed during construction of the abutments. The stability of these steep and high slopes during construction and operation period plays an important role for the safe construction and operation of the hydropower station. According to the statistical distribution of joints and fractures at the construction site, the slope is divided into a number of engineering geological zones. For each zone, a stochastic fracture network and a numerical model which is close to the real state of the fractured rock mass are established by the Monte-Carlo method. The mechanical response of fractured rock masses with different sizes of numerical models is studied using FLAC3D. The REV characteristic scale is identified for rock masses in the slopes with stochastic fracture network. Numerical simulation is performed to obtain the stress-strain curve, the mechanical parameters and the strength of the jointed rock mass in the zone. A constitutive relationship reflecting the mechanical response of the jointed rock mass in the zone is established. The Comparison between the traditional method and the method in this paper has been made at the end.

scholarly journals Anisotropic Constitutive Model of Intermittent Columnar Jointed Rock Masses Based on the Cosserat Theory

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 823 ◽  
Author(s):  
Wenbin Lu ◽  
Zhende Zhu ◽  
Xiangcheng Que ◽  
Cong Zhang ◽  
Yanxin He
Keyword(s):  
Rock Mass ◽  
Constitutive Model ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Rock Masses ◽  
Cosserat Theory ◽  
Tunnel Excavation ◽  
Jointed Rock Masses ◽  
Columnar Jointed Rock Mass ◽  
Anisotropic Constitutive Model

In this work, an anisotropic constitutive model of hexagonal columnar jointed rock masses is established to describe the distribution law of deformation and the failure of columnar joint caverns under anisotropic conditions, and is implemented to study the columnar jointed rock mass at the dam site of the Baihetan Hydropower Station on the Jinsha River. The model is based on the Cosserat theory and considers the mesoscopic bending effect on the macroscopic mean. The influences of joint plane inclination on equivalent anisotropic elastic parameters are discussed via the introduction of an off-axis transformation matrix and the analysis of an example. It is also pointed out that the six-prism columnar jointed rock mass changes from transverse isotropy to anisotropy under the influence of the angle. A numerical calculation program of the Cosserat constitutive model is developed and is applied to the simulation calculation of a Baihetan diversion tunnel to compare and analyze the respective plastic zones and stress distributions after tunnel excavation under both isotropic and anisotropic conditions. The results reveal that, compared with the isotropic model, the proposed Cosserat anisotropic model better reflects the state of stress and asymmetric distribution of the plastic zone after tunnel excavation, and the actual deformation of the surrounding rock of the tunnel is greater than that calculated by the isotropic method. The results aid in a better understanding of the mechanical properties of rock masses.

scholarly journals The Survey and the Analysis of Rock Joint and the Determination of Jointed Rock Mass Model.

1996 ◽  
pp. 145-157
Author(s):  
Chikaosa Tanimoto ◽  
Kiyoshi Kishida ◽  
Koji Tabata ◽  
Yoichi Yoshizu ◽  
Kimihiko Kunii
Keyword(s):  
Rock Mass ◽  
Rock Joint ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Mass Model

Reducing deformation effect of tunnel with Non-Deformable Support System by Jointed Rock Mass Model

2014 ◽  
Vol 40 ◽  
pp. 218-227 ◽  
Author(s):  
C.O. Aksoy ◽  
K. Oğul ◽  
İ. Topal ◽  
E. Poşluk ◽  
A. Gicir ◽  
...  
Keyword(s):  
Rock Mass ◽  
Support System ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Mass Model ◽  
Deformation Effect

Model of Damage Fracture and Damage Rheology for Jointed Rock Mass and Its Engineering Application

2006 ◽  
Vol 306-308 ◽  
pp. 1385-1390
Author(s):  
Wei Shen Zhu ◽  
Shu Cai Li ◽  
Q. Zhang ◽  
X. Qiu
Keyword(s):  
Rock Mass ◽  
Mechanical Model ◽  
Engineering Application ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Three Gorges Project ◽  
Damage Rheology ◽  
Made In ◽  
Ship Lock

This paper puts forward a damage-fracture mechanical model and a damage-rheology mechanical model for the jointed rock mass of the high slopes in the ship lock area of Three Gorges Project. These two models are used to analyze the slopes’ stability. A comparison of the computed displacements at numbers of points on the slope surfaces with the results from 3-D analysis is also made. In addition, some computing results are compared with the in-situ measured ones, showing that the model proposed is basically reliable.

Dynamic Response of Intermittent Jointed Rock Mass Subjected to Blast Waves

2006 ◽  
Vol 306-308 ◽  
pp. 1415-1420
Author(s):  
Peng Shao ◽  
Yong Zhang ◽  
Wen Ming Gao ◽  
Yong Qiang Liu
Keyword(s):  
Rock Mass ◽  
Crack Initiation ◽  
Dynamic Response ◽  
Jointed Rock ◽  
Static Field ◽  
Jointed Rock Mass ◽  
Blast Waves ◽  
Rock Joints ◽  
Rock Masses ◽  
Linear Superposition

The propagation of blast waves in intermittent jointed rock masses will result in a complex interaction between propagating waves and rock joints. Such being the case, the analysis of dynamic response of rock masses is important to rock engineering design and stability prediction. In this paper, the fracture process of intermittent jointed rock mass subjected to blast waves and initial static field, including wing crack initiation, propagation and arrest, is analyzed using linear superposition principle and sliding crack model. Crack initiation conditions and propagation lengths under incident P-waves is put forward, and the kinking effect of propagating wing cracks subjected to S-wave is also discussed. Additional, it is demonstrated that crack arrest is controlled by static field. In order to validate the correctness of dynamic response analysis, experimental investigations were performed using lucite specimens, and the experimental results show good agreement with the analytical results.

scholarly journals Aziznejad, S. and Esmaieli, K. 2015. Effects of joint intensity on rock fragmentation by impact, 11th International Symposium on Rock Fragmentation by Blasting, 24-26 August, Sydney, Australia

2017 ◽  
Author(s):  
Kamran Esmaieli
Keyword(s):  
Rock Mass ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Rock Fragmentation ◽  
Intact Rock ◽  
Particle Model ◽  
Rock Masses ◽  
Dynamic Mechanical ◽  
Bonded Particle Model ◽  
The Impact

Impact-induced rock fragmentation is a mechanism that is commonly used for rock breakage in drilling andcrushing. Additionally, rock fragmentation by blasting is frequently used in rock excavation operations.Experience shows that presence of discontinuities in rock can significantly influence the impact-induceddamage and fragmentation of rock. Quantification of the response of jointed rock masses to impact loads iscomplicated by the fact that the available laboratory tests are mainly designed for aggregates or intact rocks.It can be argued that neither of these tests adequately represent a jointed rock mass. This paper presentsthe results of a series of numerical simulations used to investigate the influence of pre-existingdiscontinuities on the impact-induced fragmentation of rock masses. The methodology includesdetermination of the static and dynamic mechanical properties of a rock unit by conducting a series oflaboratory tests on intact rock samples collected from a quarry in Canada. A 2D distinct element code,Particle Flow Code (PFC2D), was used to generate a bonded particle model in order to simulate both staticmechanical properties (Uniaxial Compressive Strength, Elastic Modulus, Poisson’s Ratio and indirect TensileStrength) and dynamic mechanical property (drop weight tensile strength) of the intact rock. The calibratednumerical model was then used to construct large-scale synthetic rock mass samples by incorporatingdiscontinuity networks of different intensity into the bonded particle model. Finally, the impact-inducedfragmentation inflicted by a rigid projectile particle on the jointed rock mass samples, simulated by asynthetic rock mass model, was determined. More fragmentation was observed for the rock mass sampleswith higher joint intensity.

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