Reinforcement with Rockbolts in Underground Powerhouse Excavation Using DDA Method

2011 ◽  
Vol 90-93 ◽  
pp. 2339-2342
Author(s):  
Song Yu ◽  
Wei Shen Zhu ◽  
Dun Fu Zhang
Keyword(s):  
Initial Stress ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Underground Powerhouse ◽  
Excavation Process ◽  
Splitting Failure ◽  
Discontinuous Deformation ◽  
Deformation Stress ◽  
The Stability ◽  
Dda Method

Discontinuous Deformation Analysis (DDA) method is used to analyze the stability, deformation and splitting failure of underground powerhouse excavation process with different lateral initial stress levels. Coefficient of lateral initial stress, reinforcement effect and joint structure pattern affecting on the surrounding rock are studied. The criterion for splitting failure in surrounding of underground is implemented to predict the depth of fracture area. It is shown that reinforcement with rockbolts will bring effects on rock surroundings in controlling deformation, stress distribution and stability.

Numerical Simulation of Coal Mining Excavation Based on Discontinuous Deformation Analysis

2011 ◽  
Vol 138-139 ◽  
pp. 187-192
Author(s):  
Ya Nan Gao ◽  
Feng Gao ◽  
M.R. Yeung ◽  
Qing Hui Jiang
Keyword(s):  
Underground Mining ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Rock Stratum ◽  
Deformation Problem ◽  
Excavation Process ◽  
Discontinuous Deformation ◽  
Movement And Deformation ◽  
Dda Method ◽  
The Continuum

The movement and deformation of rock stratum occur when the excavation is carries out during the underground mining process. Rock is a continuous-discontinuous material so the continuum mechanics method may not handle the rock problem well. The discontinuous deformation analysis (DDA) method which discretizes the rock mass to block system can describe the large displacement and deformation of rock blocks, especially the rock stratum collapse. The DDA was employed in this paper to analysis a mining excavation process. The displacement field and stress field of rock stratum was computed. The result shows that the DDA can handle the mining excavation and the rock stratum movement and deformation problem well.

Stability Analysis of Surrounding Rock with Two Groups Parallel Joints Using DDARF Method

2014 ◽  
Vol 919-921 ◽  
pp. 735-739
Author(s):  
Hai Ping Ma ◽  
Li Ge Wang ◽  
Xue Wei Li
Keyword(s):  
Stability Analysis ◽  
Uniaxial Compression ◽  
Surrounding Rock ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Compression Tests ◽  
Underground Cavern ◽  
Excavation Process ◽  
Discontinuous Deformation ◽  
The Stability

In order to analyze the stability of surrounding rocks with two groups parallel joints under different angles, a new method, DDARF (discontinuous deformation analysis for rock failure) program was adopted to investigate three cases of uniaxial compression tests of two groups parallel joints sample with the angels 30, 45 and 60. The results show the sample with 30 is least prone to be destroyed and the sample with 60 are most likely to be destroyed. Then DDARF program was also applied to investigate the underground cavern excavation process of two groups parallel joints surrounding rocks with the angels 30, 45 and 60. The results show that the stability of underground cavern with joint angel of 60 is worst in the aspect of stability.

Stability of caisson-type breakwater subjected to strong hydrodynamic impacts using discontinuous deformation analysis method

2021 ◽  
pp. 095440622110426
Author(s):  
Dong Ding ◽  
Abdellatif Ouahsine
Keyword(s):  
Penalty Method ◽  
Numerical Study ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Rear Side ◽  
Analysis Method ◽  
Discontinuous Deformation ◽  
The Stability ◽  
Dimensionless Displacement ◽  
Dda Method

A numerical study using the Discontinuous Deformation Analysis (DDA) method is proposed to analyze the effect of the caisson sliding subjected to a hydrodynamic loading in the stability of the rear side of the caisson-type breakwater. The study takes into account the slope inclination of the breakwater as well as the contact between the armour units constituting the shoreward of the breakwater, where the contact stresses are imposed through a penalty method. A dimensionless displacement parameter, [Formula: see text], is defined to investigate the instability of armor units. The results of the simulation show that the shape of the armour units plays an important role in the stability of the breakwater, where the tetrapods and the acropods give better stability than the cubic shapes, with a clear superiority of the tetrapods. They also show that the reduction in the slope clearly contributes to the stability of caisson up to a slope of 1: 2, but below this ratio of 1: 2 this stability is no longer obvious. Furthermore, a new relation of the displacement of the armour units according to the slope is established.

scholarly journals Numerical modeling of complex hydraulic fracture networks based on the discontinuous deformation analysis (DDA) method

2021 ◽  
pp. 014459872098153
Author(s):  
Yanzhi Hu ◽  
Xiao Li ◽  
Zhaobin Zhang ◽  
Jianming He ◽  
Guanfang Li
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Fracture Network ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Fracture Networks ◽  
Proposed Model ◽  
Discontinuous Deformation ◽  
Shale Reservoirs ◽  
Dda Method

Hydraulic fracturing is one of the most important technologies for shale gas production. Complex hydraulic fracture networks can be stimulated in shale reservoirs due to the existence of numerous natural fractures. The prediction of the complex fracture network remains a difficult and challenging problem. This paper presents a fully coupled hydromechanical model for complex hydraulic fracture network propagation based on the discontinuous deformation analysis (DDA) method. In the proposed model, the fracture propagation and rock mass deformation are simulated under the framework of DDA, and the fluid flow within fractures is simulated using lubrication theory. In particular, the natural fracture network is considered by using the discrete fracture network (DFN) model. The proposed model is widely verified against several analytical and experimental results. All the numerical results show good agreement. Then, this model is applied to field-scale modeling of hydraulic fracturing in naturally fractured shale reservoirs. The simulation results show that the proposed model can capture the evolution process of complex hydraulic fracture networks. This work offers a feasible numerical tool for investigating hydraulic fracturing processes, which may be useful for optimizing the fracturing design of shale gas reservoirs.

DISCONTINUOUS DEFORMATION ANALYSIS BASED ON VARIATIONAL INEQUALITY THEORY

2011 ◽  
Vol 08 (02) ◽  
pp. 193-208 ◽  
Author(s):  
WEI JIANG ◽  
HONG ZHENG
Keyword(s):  
Variational Inequality ◽  
Variational Inequality Problem ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Penalty Function Method ◽  
Weak Nonlinearity ◽  
Contact Conditions ◽  
Inequality Theory ◽  
Discontinuous Deformation ◽  
Dda Method

In the conventional discontinuous deformation analysis (DDA) method, the contact conditions are enforced by the penalty function method. Improperly selected penalty parameters might cause numerical problems. In order to evade the introduction of the penalty parameters and to avoid "open–close iteration" that can not assure convergence, this study reformulates the DDA as a variational inequality problem. Based on the fact that the solution of a variational inequality is a fixed point of a natural projection map, the problem is reduced to the solution of nonsmooth equations with weak nonlinearity. Then, the Path Newton Method (PNM) is utilized to solve the equations. Some practical examples originally designed by Shi are reanalyzed, which demonstrates that the new DDA method is feasible.

A Three-Dimensional Discontinuous Deformation Analysis Method for Investigating the Effect of Slope Geometrical Characteristics on Rockfall Behaviors

2019 ◽  
Vol 16 (08) ◽  
pp. 1850122 ◽  
Author(s):  
Guoyang Liu ◽  
Junjie Li
Keyword(s):  
Slope Angle ◽  
Three Dimensional ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Motion Trajectories ◽  
Geometrical Characteristics ◽  
Damage Degree ◽  
Slope Excavation ◽  
Discontinuous Deformation ◽  
Dda Method

In the present study, a three-dimensional discontinuous deformation analysis (3D DDA) method was developed and used to investigate the effect of slope geometrical characteristics on rockfall behaviors. The slope geometrical characteristics of rockfall, such as the slope height, slope angle and slope shape, were summarized, and the corresponding calculation models were proposed. The algebraic computation and contact mechanics of the three-dimensional (3D) global contact theory were illustrated and implemented into the 3D DDA method. The accuracy of the developed 3D DDA method was verified through the four basic movement forms of rockfall: freefalling (oblique projectile), sliding, rolling and bouncing. Numerical examples were performed to study rockfall behaviors under different slope geometrical characteristics by analyzing the kinetic energy or velocity conversion, motion trajectories, and damage degree and range of moving blocks. The results demonstrate that the 3D DDA method can accurately simulate rockfall movement, which is significantly affected by slope geometrical characteristics. Furthermore, some suggestions for slope excavation and protection were put forward.

STABILITY ANALYSES FOR ANCIENT MASONRY STRUCTURES USING DISCONTINUOUS DEFORMATION ANALYSIS AND NUMERICAL MANIFOLD METHOD

2011 ◽  
Vol 08 (02) ◽  
pp. 247-275 ◽  
Author(s):  
TAKESHI SASAKI ◽  
IKUO HAGIWARA ◽  
KASTUJI SASAKI ◽  
RYUNOSHIN YOSHINAKA ◽  
YUZO OHNISHI ◽  
...  
Keyword(s):  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Numerical Manifold Method ◽  
Masonry Structures ◽  
Stress Distributions ◽  
Isoparametric Element ◽  
Discontinuous Deformation ◽  
The Stability ◽  
Numerical Manifold ◽  
Physical Phenomena

In this paper, the stability including stress distribution of two ancient masonry structures, the pyramid of the Pharaoh Khufu, Egypt and the Pont of Gard, were analyzed using discontinuous deformation analysis (DDA) and numerical manifold method (NMM). For the simulation using NMM, the newly developed four-node isoparametric element was used. The stress distributions/concentration were calculated and compared between the two methods. The calculated results show qualitative agreement with observations. DDA and NMM are applicable to simulate the physical phenomena of masonry structures.

scholarly journals Reproduction Method of Rockfall Geologic Hazards Based on Oblique Photography and Three-Dimensional Discontinuous Deformation Analysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaodong Fu ◽  
Haifeng Ding ◽  
Qian Sheng ◽  
Jian Chen ◽  
He Chen ◽  
...  
Keyword(s):  
Geometric Characteristic ◽  
Three Dimensional ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Geologic Hazard ◽  
Block System ◽  
Geologic Hazards ◽  
Discontinuous Deformation ◽  
Reproduction Method ◽  
Dda Method

Rockfall geologic hazards are widely distributed. Due to their concealed nature, rockfalls are difficult to investigate using traditional contact survey methods, and the hazards they pose affect major projects and people’s safety. Reproducing methods, including scene survey and movement process analysis, are primary tasks used to prevent these hazards; however, few reconstruction methods can directly apply the parameters of the rockfall geologic hazards obtained by the scene survey to evaluate the movement process. To address this problem, a method of reproduction based on oblique photography and three-dimensional discontinuous deformation analysis (3D-DDA) is proposed; the method consists of three key techniques (oblique photography, 3D rock block system modeling, and 3D rock block system analysis). First, geometric characteristic parameters of the terrain, rockfall, and discontinuities are extracted based on oblique photography using an unmanned aerial vehicle (UAV). Second, the block system model of rockfall is reconstructed by using 3D computational geometry theory and taking these geometric characteristic parameters as an input. Finally, the whole evolution process of rockfall geologic hazard, including initiation, movement, and accumulation, is simulated by the 3D-DDA method. To verify the practicability of this reproduction method, a typical rockfall geologic hazard, located in the K8 + 050 section of the Gaohai expressway, Yunnan, China, is studied. In addition, the characteristics of 19 dangerous rock masses in the survey area are clarified, and the geometric features of the discontinuities in the rock masses are extracted based on oblique photography using an UAV. The block system model of a potential rockfall is reconstructed, the movement trajectory is simulated by the 3D-DDA method, and the evolution process of velocity and kinetic energy of the rockfall verifies that the spatial layout of the current three-level passive protective nets system is reasonable. The case study indicates that the proposed method provides a geological and mechanical model for the risk assessment of rockfall geologic hazards.

Sign in / Sign up

Export Citation Format

Share Document