Stability Study on Jointed Rock Mass Affected by Fissure Water Pressure

2014 ◽  
Vol 624 ◽  
pp. 577-581
Author(s):  
Wei Qiang Xue ◽  
Wei Shen Zhu ◽  
Jin Wei Fu ◽  
Chao Jia ◽  
Shuai Guo
Keyword(s):  
Rock Mass ◽  
Water Pressure ◽  
Engineering Application ◽  
Jointed Rock ◽  
Stability Study ◽  
Strong Impact ◽  
Excavation Process ◽  
Initiation And Propagation ◽  
The Stability ◽  
Fissure Water

Joints and fissures have a strong impact on the stability of engineering rock mass. In this paper, a self-improved analysis program of FLAC3D is adopted to study problems in fluid-solid coupling field. Then, by simulating the excavation process of a slope under the effect of fissure water pressure, the crack initiation and propagation in engineering rock mass reappears. Besides, the numerical simulation results are decent and effective, which can provide some references for engineering application.

The Study on Failure Mechanism of 3D Cracked Rock Mass under Fissure Water Pressure

2013 ◽  
Vol 353-356 ◽  
pp. 669-672
Author(s):  
Wei Qiang Xue ◽  
Wei Shen Zhu ◽  
Dun Fu Zhang ◽  
Jin Wei Fu
Keyword(s):  
Rock Mass ◽  
Failure Mechanism ◽  
Water Pressure ◽  
Rock Masses ◽  
Propagation Process ◽  
Initiation And Propagation ◽  
Secondary Cracks ◽  
Simulation Results ◽  
Fissure Water ◽  
Good Agreement

In this paper, the failure mechanism of rock-like specimens with built-in 3D double cracks under fissure water pressure was numerically investigated. The initiation and propagation process of secondary cracks under fissure water pressure was simulated by using the modified elasto-brittle model and the superfine meshing method in the FLAC3D program. The fluid-solid coupling in cracked rock masses was preliminarily studied. Some of the simulation results are in good agreement with the previous results tested by scholars.

Analysis on Rock Mass Around an Underground Crude Oil Storage Caverns in Containment of Groundwater Considering Fluid Solid Coupling

2012 ◽  
Vol 588-589 ◽  
pp. 1918-1921
Author(s):  
Shang Yang Yang ◽  
Long Yun Zhang
Keyword(s):  
Rock Mass ◽  
Crude Oil ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Compression Tests ◽  
Oil Storage ◽  
Excavation Process ◽  
The Stability ◽  
Seepage Law ◽  
Petroleum Storage

Triaxial compression tests have been performed to determine the properties of the rock mass around an unlining underground crude oil storage caverns which is the first one in China. The execution situation of the tunnel project and the seepage law of groundwater are taken into account; the stress and the seepage field around the tunnel in different working states are simulated by applying Comsol around a underground crude oil storage caverns.According to the test results, it was found that the excavation process may arise the local damage,the extension of the excavation induced loose zone ranges from 0 to 15.6 m, depending on the buried depth of the caverns. According to numerical simulation results, the crown settlement and stress concentration is depended on the buried depth and the water pressure distribution after the excavation of the main cavity. This research results can provide the reference for analysis on the stability of the underground cavities under low stress level and on the water sealed underground petroleum storage rock caverns.

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 Coupling Effect of Creep Deformation and Prestress Loss of Anchored Jointed Rock

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Bairu Zhu ◽  
Yang Song ◽  
Heping Wang ◽  
Yongqi Li
Keyword(s):  
Rock Mass ◽  
Stress Level ◽  
Coupling Effect ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Calculation Model ◽  
Prestress Loss ◽  
Stress States ◽  
The Stability ◽  
Anchor Design

To explore the variation behaviour of anchor jointed rock subject to high in situ stress states, a coupling effect calculation model based on stress equality was established based on the original rheological model of rock by combining element combination theory and experiment, and the model was verified. The coupling effect between rock mass creep and bolt prestress loss is established by setting the deterioration function of bolt prestress loss. The uniaxial creep test is performed on specimens with different joint angles, and the results show that the prestress loss time in anchor rods decreases linearly with increasing stress level. With increasing stress level, the time of prestress loss decreases linearly with the increase in stress level. With increasing axial load, the deformation caused by the transverse expansion stress of the specimen can offset the compression deformation of the prestressed anchor rod. The relationship between prestress loss in anchors and creep of rock is solved theoretically, and the stability criterion for anchor jointed rock is proposed. The results of this study provide a scientific reference for anchor design of deep jointed rock mass.

Stability Analysis about the Impact of Soft Rock to the Underground Cavern Group

2013 ◽  
Vol 706-708 ◽  
pp. 560-564
Author(s):  
Yi Huan Zhu ◽  
Guo Jian Shao ◽  
Zhi Gao Dong
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Stability Analysis ◽  
Soft Rock ◽  
Element Model ◽  
Underground Excavation ◽  
Power Station ◽  
Excavation Process ◽  
The Stability ◽  
The Impact

Soft rock is frequently encountered in underground excavation process. It is difficult to excavate and support in soft rock mass which has low strength, large deformation and needs much time to be out of shape but little time to be self-stabilized. Based on a large underground power station, finite element model analysis was carried out to simulate the excavation process and the results of displacement, stress and plasticity area were compared between supported and unsupported conditions to evaluate the stability of the rock mass.

Displacement Back Analysis Research on Bolt-Grouting Supporting Parameter of Rock Mass in Jointed Rock Roadway

2004 ◽  
Vol 261-263 ◽  
pp. 1563-1568
Author(s):  
Le Wen Zhang ◽  
Shu Chen Li ◽  
Shu Cai Li
Keyword(s):  
Rock Mass ◽  
Mass Parameter ◽  
Back Analysis ◽  
Jointed Rock ◽  
Singular Value ◽  
Surrounding Rock ◽  
Elastic Model ◽  
Rock Stability ◽  
The Stability ◽  
Rock Roadway

The method of bolt-grouting supporting, grouting into surrounding rock mass by bolts in jointed rock mass roadway, is obtained wide application. However, it is difficult to determine rock mass parameter of bolt-grouting supporting. This paper begins with the displacement, which is measured easily in practice. The method of back analysis is adopted to calculate the equivalent mechanics parameters of bolt-grouting rock mass. In process of back analysis three mechanics models is supposed which are homogeneous elastic model, inhomogeneous elastic model and elastic-plastic model and corresponding algorithm is established. What's more, this paper discusses the stability of inverse algorithm and copes the problem of back analysis parameter probably instable with QR decomposed algorithm and singular value decomposed algorithm, which will be a theoretical base to determine the mechanics parameter of bolt-grouting supporting rock mass and to estimate the surrounding rock stability. In a word, the method is established to estimate mechanics parameters of bolt-grouting jointed surrounding rock mass, and some significant results are obtained, which are of reference for actual project.

scholarly journals Numerical Simulation of Stress Arching Effect in Horizontally Layered Jointed Rock Mass

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1138
Author(s):  
Xiao Huang ◽  
Huaining Ruan ◽  
Chong Shi ◽  
Yang Kong
Keyword(s):  
Rock Mass ◽  
Pressure Coefficient ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Beam Structure ◽  
Underground Engineering ◽  
Joint Spacing ◽  
Arching Effect ◽  
The Stability

Stress arching effect during the excavation of broken surrounding rock in underground engineering has an important influence on the stability of surrounding rock after underground excavation. To determine the stress arching effect in horizontally layered jointed rock mass, the stress arching characteristics of surrounding rock mass after excavation is analyzed in this study by using a series of numerical tests. The formation mechanism of stress arch is revealed through a comparison of the stress characteristics of a voussoir beam structure and theoretical analysis of multi-block mechanical relationship of jointed rock mass. The method for determining the boundaries of a stress arching zone is proposed, and the influence of various factors on a stress arch is further discussed. Results show that after the excavation of horizontally layered jointed rock mass, the stress arch bunch (SAB) is formed in the lower strata above the cavern, and the global stress arch (GSA) is formed in the higher strata, both of which are symmetrical arch stress patterns. The SAB is the mechanical manifestation of the voussoir beam structure formed by several low-level sandstone layers, and the GSA is caused by the uneven displacement between blocks. Compared with the GSA, the SAB is more sensitive to various influencing factors. The extent of stress arching zone decreases with the increase of an internal friction angle of the joint, lateral pressure coefficient, and overburden depth. In addition, the joint spacing of rock strata is conducive to the development of a stress arch. Results can provide technical support for deformation control and the stability analysis of broken surrounding rock in underground engineering.

scholarly journals Model Test Study on the Anisotropic Characteristics of Columnar Jointed Rock Mass

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1528
Author(s):  
Zhende Zhu ◽  
Xiangcheng Que ◽  
Zihao Niu ◽  
Wenbin Lu
Keyword(s):  
Rock Mass ◽  
Failure Modes ◽  
Engineering Application ◽  
Jointed Rock ◽  
Structural Features ◽  
Jointed Rock Mass ◽  
Hexagonal Prism ◽  
Compression Tests ◽  
Test Study ◽  
Columnar Jointed Rock Mass

Because of its special structure, the anisotropic properties of columnar jointed rock mass (CJRM) are complicated, which brings difficulty to engineering construction. To comprehensively study the anisotropic characteristics of CJRM, uniaxial compression tests were conducted on artificial CJRM specimens. Quadrangular, pentagonal and hexagonal prism CJRM models were introduced, and the dip direction of the columnar joints was considered. Based on the test results and the structural features of the three CJRM models, the deformation and strength characteristics of CJRM specimens were analyzed and compared. The failure modes and mechanisms of artificial specimens with different dip directions were summarized in accordance with the failure processes and final appearances. Subsequently, the anisotropic degrees of the three CJRM models in the horizontal plane were classified, and their anisotropic characteristics were described. Finally, a simple empirical expression was adopted to estimate the strength and deformation of the CJRM, and the derived equations were used in the Baihetan Hydropower Station project. The calculated values are in good agreement with the existing research results, which reflects the engineering application value of the derived empirical equations.

scholarly journals A Model of Anisotropic Property of Seepage and Stress for Jointed Rock Mass

2013 ◽  
Vol 2013 ◽  
pp. 1-19 ◽  
Author(s):  
Pei-tao Wang ◽  
Tian-hong Yang ◽  
Tao Xu ◽  
Qing-lei Yu ◽  
Hong-lei Liu
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Underground Mining ◽  
Principal Direction ◽  
Water Pressure ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Metal Mine ◽  
Roadway Stability

Joints often have important effects on seepage and elastic properties of jointed rock mass and therefore on the rock slope stability. In the present paper, a model for discrete jointed network is established using contact-free measurement technique and geometrical statistic method. A coupled mathematical model for characterizing anisotropic permeability tensor and stress tensor was presented and finally introduced to a finite element model. A case study of roadway stability at the Heishan Metal Mine in Hebei Province, China, was performed to investigate the influence of joints orientation on the anisotropic properties of seepage and elasticity of the surrounding rock mass around roadways in underground mining. In this work, the influence of the principal direction of the mechanical properties of the rock mass on associated stress field, seepage field, and damage zone of the surrounding rock mass was numerically studied. The numerical simulations indicate that flow velocity, water pressure, and stress field are greatly dependent on the principal direction of joint planes. It is found that the principal direction of joints is the most important factor controlling the failure mode of the surrounding rock mass around roadways.

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