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.

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.

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.

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.

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