scholarly journals A Strain-Softening Constitutive Model of Heterogeneous Rock Mass Considering Statistical Damage and Its Application in Numerical Modeling of Deep Roadways

2019 ◽  
Vol 11 (8) ◽  
pp. 2399 ◽  
Author(s):  
Guang Li ◽  
Fengshan Ma ◽  
Gang Liu ◽  
Haijun Zhao ◽  
Jie Guo
Keyword(s):  
Rock Mass ◽  
Strain Softening ◽  
Mining Area ◽  
Jointed Rock ◽  
Simulation Software ◽  
Softening Behavior ◽  
Underground Caverns ◽  
Heterogeneous Rock ◽  
The Stability ◽  
Statistical Damage

During the construction of underground caverns, the stability of deep underground cavern excavation, which affects the safety and sustainable development of such projects, is a hot issue. First, based on the mechanical properties of surrounding rock in deep tunnels, the strain-softening behavior, damage, and heterogeneity of rock masses are analyzed. Then, a strain-softening model of heterogeneous jointed rock mass that considers statistical damage (SSD) is developed and implemented through FLAC3D simulation software. Finally, the SSD is applied to a deep roadway in the Jinchuan mining area, and a comparative analysis of the computation results of the Mohr–Coulomb (MC) model and the strain-softening (SS) model are carried out. The numerical results are compared with the field-monitoring results, which show that the SSD model simulated the behavior of the surrounding rocks well. The results show that the deformations of the roof and floor are larger, which may serve as a reference for the support pattern of deep roadways.

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 Numerical Simulation of Fluid-Solid Coupling in Surrounding Rock for River Stope Mining

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Haiping Yuan ◽  
Chenghao Chen ◽  
Zhongming He ◽  
Yixian Wang
Keyword(s):  
Rock Mass ◽  
Mining Area ◽  
Calculation Model ◽  
Rock Bridge ◽  
The Road ◽  
Ore Body ◽  
Safety And Reliability ◽  
Mining Disturbance ◽  
The Stability ◽  
Seepage Channel

Mining disturbance will induce further weakening of faults and rock bridges, improve rock mass permeability and, in serious cases, conduct surface rivers to cause disasters. A numerical calculation model of river-fault in the mining area is established. Based on the fluid-solid coupling theory of rock mass, the influence of mining disturbance on the development and evolution process of rock bridge rupture and river-fault-stope potential seepage channel is simulated and calculated. Research studies show that under the disturbance of ore body mining, it is possible to form a channel from the river to fault to seepage and drainage in the stope. The disturbance of ore body mining has no great adverse effect on the stability of the rock mass at the top of F2 fault. The rock mass damage caused by mining is only distributed in local areas, and the rock bridge between the river, fault, and stope is not completely connected. The fracture of mining rock mass leads to the increase in permeability of rock mass, and seepage tends to spread in the direction of the fault, but there is no obvious through drainage channel from surface water to the stope. The results of research provide technical guidance for the mine to use the filling mining method after the river does not change the road safety and reliability certification and can also provide reference for similar mines.

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.

scholarly journals Research on the Layered Rock Mass Excavation Relaxation Stability of Underground Caverns

2020 ◽  
Vol 165 ◽  
pp. 03024
Author(s):  
Ying Zhang ◽  
Heng Zhou ◽  
Shengjie Di ◽  
Xi Lu
Keyword(s):  
Rock Mass ◽  
Mechanical Characteristics ◽  
Generation System ◽  
Yield Zone ◽  
Layered Rock ◽  
Underground Caverns ◽  
Structure Surface ◽  
Layered Rock Mass ◽  
Power Generation System ◽  
The Stability

In order to compare the influence of rock mass parameters weakening on the deformation and stability of excavation caverns in layered rock mass, based on power generation system caverns of a hydropower station, the stability and deformation of the caverns is analyzed. The results show that the mechanical characteristics of the structure surface play a major role in controlling the stability of caverns. And the displacement and yield zone value of plan 3, which adopt elastic-plastic softening model, are significantly larger than other two. The method which consider the residual strength of structure surface is more suitable for the excavation calculation of layered rock mass cavern.

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.

Study on Post-Failure Deformation and Residual Strength of Rock Mass Based on Hoek-Brown Criterion

2012 ◽  
Vol 170-173 ◽  
pp. 121-124
Author(s):  
Jian Xin Han ◽  
Xing Hua Tong ◽  
Lei Wang ◽  
Guo Fu Sun
Keyword(s):  
Rock Mass ◽  
Residual Strength ◽  
Strain Softening ◽  
Strain Curve ◽  
Strength Criterion ◽  
Stress Strain Curve ◽  
Strength Parameters ◽  
Softening Parameter ◽  
Residual Values ◽  
The Stability

In order to predict the stability of surrounding rock mass in geotechnical engineering, it is important to study the post-failure deformation property and residual strength of rock mass. Based on evolutional behavior of strength parameters, aiming at generalized Hoek-Brown strength criterion, selecting major principal strain as strain softening parameter, this paper presents the method of solving post-failure stress-strain curve . In numerical case, the effect of evolutional law of strength parameters ， and to deformation and residual strength is discussed and we can draw the following conclusions: the greater the residual values of ， are and the smaller the residual value of is, the post-failure strain softening curve falls more gently and the greater the residual strength is.

scholarly journals An Enhanced Ubiquitous-Joint Model for a Rock Mass With Conjugate Joints and Its Application on Excavation Simulation of Large Underground Caverns

2021 ◽  
Vol 9 ◽  
Author(s):  
Xianlun Leng ◽  
Chuan Wang ◽  
Qian Sheng ◽  
Jian Chen ◽  
Hailun Li
Keyword(s):  
Rock Mass ◽  
Failure Modes ◽  
Triaxial Compression ◽  
Local Coordinate System ◽  
Failure Criteria ◽  
Jointed Rock ◽  
Joint Model ◽  
Compression Tests ◽  
Mechanical Behaviors ◽  
Underground Caverns

A conjugate jointed rock mass (CJRM) is a rock mass with two sets of intersecting joints formed from intact rock under shear. Its mechanical properties and excavation-induced hazards of large underground caverns are different from those of common rock masses because of the unique geological origin thereof. To demonstrate numerically the excavation responses of CJRM, the ubiquitous-joint model is enhanced by consideration of the specific mechanical behaviors of the rock mass. In the enhanced model, CJRM is considered as the composite of columns of rock and two sets of weak planes of joints. The local coordinates, failure modes, and failure sequences of the rock columns and joints are redefined based on the composite characteristics of CJRM, and the failure criteria and plastic potential functions are accordingly modified. The enhanced model is verified numerically by triaxial compression tests and then employed to simulate the excavation of large underground caverns of a pumped storage power station in China. Results show that the modification of the local coordinate system, failure modes, and failure sequences made in the enhanced model is suited to the simulation of the mechanical behaviors of CJRM. Compared with the original ubiquitous-joint model, the enhanced model allows better predictions of the distribution of plastic zones and magnitudes of deformations in simulating underground excavations in CJRM and helps to assess the excavation-triggered hazards more accurately.

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.

Sign in / Sign up

Export Citation Format

Share Document