scholarly journals Seismic Response for Wave Propagation across Joints with Equally and Unequally Close-Open Behaviours

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Qi Zhang ◽  
Zhengliang Li ◽  
Tao Yu
Keyword(s):  
Wave Propagation ◽  
Seismic Response ◽  
Seismic Waves ◽  
Incident Angle ◽  
In Situ Stress ◽  
Rock Joints ◽  
Stress Wave Propagation ◽  
S Wave ◽  
Maximum Deformation

The interaction between rock joints and seismic waves is critical in rock engineering when rock mass is suffered from human-induced or natural earthquakes. Stress wave propagation across rock joints is usually dependent on the seismic response of the joints. Wave propagation may cause joints close or open under the in situ stress. In this paper, the seismic response for wave propagation with an arbitrary incident angle impinging on joints is studied. Both reflection and transmission usually occurring at the two interfaces of the joint are considered, respectively. Wave propagation equations with equally and unequally close-open behaviours are deduced firstly, which can be applied for the general cases of arbitrary incident P- or S-wave. Then, wave propagation across joints with normal and oblique incident P- and S-waves is analyzed by considering the equally and unequally close-open behaviours and verified by comparing with the existing methods. Finally, several parametric studies are conducted to evaluate the effect of in situ stress on transmitted waves, the effect of the incident frequency on the maximum deformation of joints, and the effect of the incident angle on the maximum deformation of joints. The wave propagation equations derived in the study are more feasible and can well analyze the seismic response of wave propagation for the most general cases of different incident waveforms.

Study on S-wave propagation through parallel rock joints under in situ stress

2020 ◽  
pp. 1-24 ◽  
Author(s):  
Tingting Liu ◽  
Xinping Li ◽  
Yun Zheng ◽  
Yi Luo ◽  
Yunhua Guo ◽  
...  
Keyword(s):  
Wave Propagation ◽  
In Situ Stress ◽  
Rock Joints ◽  
S Wave

scholarly journals Simulation of seismic waves at the earth's crust (brittle–ductile transition) based on the Burgers model

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 1001-1010 ◽  
Author(s):  
J. M. Carcione ◽  
F. Poletto ◽  
B. Farina ◽  
A. Craglietto
Keyword(s):  
Seismic Waves ◽  
In Situ Stress ◽  
Seismic Attenuation ◽  
Earth’S Crust ◽  
S Wave ◽  
Fourier Pseudospectral Method ◽  
Stress Criterion ◽  
Brittle Ductile Transition ◽  
Earth's Crust

Abstract. The earth's crust presents two dissimilar rheological behaviors depending on the in situ stress-temperature conditions. The upper, cooler part is brittle, while deeper zones are ductile. Seismic waves may reveal the presence of the transition but a proper characterization is required. We first obtain a stress–strain relation, including the effects of shear seismic attenuation and ductility due to shear deformations and plastic flow. The anelastic behavior is based on the Burgers mechanical model to describe the effects of seismic attenuation and steady-state creep flow. The shear Lamé constant of the brittle and ductile media depends on the in situ stress and temperature through the shear viscosity, which is obtained by the Arrhenius equation and the octahedral stress criterion. The P and S wave velocities decrease as depth and temperature increase due to the geothermal gradient, an effect which is more pronounced for shear waves. We then obtain the P−S and SH equations of motion recast in the velocity-stress formulation, including memory variables to avoid the computation of time convolutions. The equations correspond to isotropic anelastic and inhomogeneous media and are solved by a direct grid method based on the Runge–Kutta time stepping technique and the Fourier pseudospectral method. The algorithm is tested with success against known analytical solutions for different shear viscosities. A realistic example illustrates the computation of surface and reverse-VSP synthetic seismograms in the presence of an abrupt brittle–ductile transition.

scholarly journals Stress Wave Propagation through Rock Joints Filled with Viscoelastic Medium Considering Different Water Contents

2020 ◽  
Vol 10 (14) ◽  
pp. 4797 ◽  
Author(s):  
Xiaolin Huang ◽  
Shengwen Qi ◽  
Bowen Zheng ◽  
Youshan Liu ◽  
Lei Xue ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Water Content ◽  
Seismic Response ◽  
Transmission Coefficient ◽  
Stress Wave ◽  
Viscoelastic Medium ◽  
Rock Joints ◽  
Stress Wave Propagation ◽  
Multiple Reflections ◽  
Joint Spacing

A rock mass often contains joints filled with a viscoelastic medium of which seismic response is significant to geophysical exploration and seismic engineering design. Using the propagator matrix method, an analytical model was established to characterize the seismic response of viscoelastic filled joints. Stress wave propagation through a single joint highly depended on the water content and thickness of the filling as well as the frequency and incident angle of the incident wave. The increase in the water content enhanced the viscosity (depicted by quality factor) of the filled joint, which could promote equivalent joint stiffness and energy dissipation with double effects on stress wave propagation. There existed multiple reflections when the stress wave propagated through a set of filled joints. The dimensionless joint spacing was the main controlling factor in the seismic response of the multiple filled joints. As it increased, the transmission coefficient first increased, then it decreased instead, and at last it basically kept invariant. The effect of multiple reflections was weakened by increasing the water content, which further influenced the variation of the transmission coefficient. The water content of the joint filling should be paid more attention in practical applications.

scholarly journals Simulation of seismic waves at the Earth crust (brittle-ductile transition) based on the Burgers model

2014 ◽  
Vol 6 (1) ◽  
pp. 1371-1400 ◽  
Author(s):  
J. M. Carcione ◽  
F. Poletto ◽  
B. Farina ◽  
A. Craglietto
Keyword(s):  
Seismic Waves ◽  
Grid Method ◽  
In Situ Stress ◽  
Seismic Attenuation ◽  
S Wave ◽  
Fourier Pseudospectral Method ◽  
Stress Criterion ◽  
Brittle Ductile Transition ◽  
The Earth

Abstract. The Earth crust presents two dissimilar rheological behaviours depending on the in-situ stress-temperature conditions. The upper, cooler, part is brittle while deeper zones are ductile. Seismic waves may reveal the presence of the transition but a proper characterization is required. We first obtain a stress–strain relation including the effects of shear seismic attenuation and ductility due to shear deformations and plastic flow. The anelastic behaviour is based on the Burgers mechanical model to describe the effects of seismic attenuation and steady-state creep flow. The shear Lamé constant of the brittle and ductile media depends on the in-situ stress and temperature through the shear viscosity, which is obtained by the Arrhenius equation and the octahedral stress criterion. The P- and S-wave velocities decrease as depth and temperature increase due to the geothermal gradient, an effect which is more pronounced for shear waves. We then obtain the P-S and SH equations of motion recast in the velocity-stress formulation, including memory variables to avoid the computation of time convolutions. The equations correspond to isotropic anelastic and inhomogeneous media and are solved by a direct grid method based on the Runge–Kutta time stepping technique and the Fourier pseudospectral method. The algorithm is tested with success against known analytical solutions for different shear viscosities. A realistic example illustrates the computation of surface and reverse-VSP synthetic seismograms in the presence of an abrupt brittle-ductile transition.

scholarly journals Effects of Unidirectional In Situ Stress on Crack Propagation of a Jointed Rock Mass Subjected to Stress Wave

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhanfeng Fan ◽  
Jianhua Cai
Keyword(s):  
Wave Propagation ◽  
Rock Mass ◽  
Crack Propagation ◽  
Stress Wave ◽  
Large Scale ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Jointed Rock Mass ◽  
Stress Wave Propagation

This paper proposes a large-scale experiment combined with multiple cement mortar blocks to simulate stress wave propagation across a jointed rock mass under unidirectional in situ stress. Two identical mortar block models with smooth, dry, and unfilled joints were poured. The stress waves in Model 1 and Model 2 were generated by an electric spark source and a blast-induced source, respectively. The effects of these two excitation sources on stress wave propagation were compared through crack propagation experiments. The experimental results show that the peak value of the transmitted strain wave decreases as the in situ stress increases. The unidirectional in situ stress has a certain inhibitory effect on the stress wave propagation. It also indicates that for Model 1 with the electric spark source, no cracks on the upper surface, but a Livingstone blasting crater at the bottom is generated. For Model 2 with the blast-induced source, cracks on the upper surface and a blasting crater at the bottom are produced. The results verify the similarity between the electric spark source and the explosive source. The two-dimensional finite element program (ANSYS/LS-DYNA) was applied to further simulate the crack propagation of a jointed rock mass under different in situ stresses. The results of numerical simulation verify that the in situ stress has a clear guiding effect on the crack propagation.

scholarly journals New Method to Design Coal Pillar for Lateral Roof Roadway Based on Mining-Induced Stress: A Case Study

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Feng Wang ◽  
Shaojie Chen ◽  
Jialin Xu ◽  
Mengzi Ren
Keyword(s):  
Stress Distribution ◽  
Coal Pillar ◽  
In Situ Stress ◽  
New Method ◽  
Maximum Deformation ◽  
Induced Stress ◽  
Stress Contour ◽  
Longwall Panel ◽  
Overlying Strata

The traditional method to design coal pillar for lateral roof roadway was established based on the mining-induced strata movement contour which is considered as a straight line, while ignoring the variations of the internal strata deformation law as well as stress distribution characteristics. In order to make up for this deficiency, in this study, evolution of mining-induced stress in the overlying strata was simulated using physical and numerical simulations, and a method to design coal pillar for lateral roof roadway based on mining-induced stress was proposed. The results indicate that the stress of the overlying strata is redistributed during excavation, and the stress distribution can be divided into a stress-relaxation area, a stress-concentration area, and an in situ stress area. The contour line of 1.05 times the in situ stress is used to define the mining-induced stress contour. Stress inside the contour is redistributed while outside the contour the overlying strata are still within the in situ stress area. Mining-induced stress contour presents a concave-upward type from coal seam to the overlying strata that cannot be merged into a straight one due to their different characteristics of movement and deformation. With this in mind, this study proposed a method to design the width of coal pillar for lateral roof roadway according to the mining-induced stress contour. According to mining-induced stress contour, the width of coal pillar for lateral roof roadway of longwall panel 31100 is 160 m, and the maximum deformation of the roadway is 270 mm. The new method can definitely meet engineering demands.

scholarly journals Effects of Oblique Incidence of SV Waves on Nonlinear Seismic Response of a Lined Arched Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Dunyu Lyu ◽  
Sha Ma ◽  
Chu Yu ◽  
Congcong Liu ◽  
Xiaowei Wang ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Wave Field ◽  
Seismic Response ◽  
Seismic Wave ◽  
Oblique Incidence ◽  
Incident Angle ◽  
Three Dimensional ◽  
Seismic Wave Propagation ◽  
Finite Element Program ◽  
Artificial Boundaries

The incident direction of earthquake motion is an important factor affecting the seismic response of underground structures. In this study, a three-dimensional (3D) oblique incidence method of SV waves is proposed and the effects of incident angles of SV waves on the seismic response of a lined arched tunnel are evaluated. Based on wave field decomposition principle and equivalent node force method and together with viscous-spring artificial boundary, the oblique incidence method of SV waves is implemented by transforming seismic wave field into the equivalent nodal forces acting on the artificial boundaries. By deriving the distance of the incident waves and the reflected wave on free surface to artificial boundaries, this method can comprehensively consider the phase difference of the seismic wave propagation and the influence of the damping effect of the rock medium on the seismic wave propagation. The method is programed into a dynamic finite element program and its effectiveness is examined by a numerical example. Consequently, the oblique incidence method is applied to evaluate the seismic behaviors of the tunnel. The numerical results reveal that (1) the oblique incidence of the seismic wave results in a larger seismic response; (2) the response amplitudes of the stress and displacement increase with the increase of incident angles and reaching the maximum in the case of 30° incident angle; (3) the damage extent increases with an increase in the incident angles, and the oblique incidence of the seismic wave is believed to increase the spatial difference of damage distribution.

scholarly journals Pengembangan Pengujian Crashworthiness dengan Simulasi Numerik Menggunakan Model Impact Transferability

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Felix Dionisius ◽  
Jos Istiyanto ◽  
Suliono Suliono ◽  
Yusup Nur Rohmat
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Wave Propagation ◽  
Stress Wave Propagation ◽  
Explicit Finite Element Method ◽  
Explicit Finite Element ◽  
Real Experiment ◽  
Maximum Deformation ◽  
Stress Propagation ◽  
Thin Walled

Collision test is needed in transportation area in order to anticipate injuries of passangers when the accident occurred. Therefore, this test must be done for achieving standar requirements which is known by crashworthiness. This paper discussed about development of crasworthiness test by using modelling impact transferability by numerical simulation. The goal is to know the error of maximum deformation when given axial dynamic loading between numerical simulation and real experiment. Furthermore, analitic was used to validate duration of stress wave propagation from result of numerical simulation. This simulation used explicit finite element method by using PAM-Crash. The component of this research was impactor and impact of transferability with 80 and 27 kg of mass. The square tube-thin walled structure with holes as crush initator 3 mm of diameter was used as specimen. The result shows maximum deformation and duration of stress propagation error which are 3.90 % and 14.89 %. 

scholarly journals Study on Seismic Response and Damping Measures of Surrounding Rock and Secondary Lining of Deep Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Baoli Tang ◽  
Yongqiang Ren
Keyword(s):  
Numerical Calculation ◽  
Seismic Response ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Theoretical Research ◽  
Concrete Lining ◽  
Tunnel Construction ◽  
Geological Conditions ◽  
Safety And Stability

Tunnel construction is gradually developing to areas with high in situ stress; the deeper the tunnel construction, the more intense the earthquake disturbance. Under the background of frequent earthquakes, the seismic characteristics of tunnels become an important content related to the safety and stability of engineering structures. In view of the key problems of seismic response and vibration reduction measures for complex deep buried tunnels, the methods of advanced grouting and foam concrete aseismic are studied in this paper. Firstly, through geological survey, the in situ stress and geological conditions of the study area are analyzed. The structural characteristics of surrounding rock and related rock mechanics parameters are analyzed. The failure criterion of concrete lining under dynamic load is studied theoretically, and the relevant numerical calculation parameters are modified. A numerical model based on viscous boundary conditions is established. Through numerical calculation, the seismic response of tunnel surrounding rock and lining under different damping measures is analyzed. The research results have theoretical research value and social and economic benefits for ensuring the safety and stability of tunnel structure and improving the seismic fortification level.

scholarly journals DYNAMIC PHOTOELASTIC STUDIES OF P AND S WAVE PROPAGATION IN PRESTRESSED MEDIA

Geophysics ◽  
1969 ◽  
Vol 34 (5) ◽  
pp. 696-712 ◽  
Author(s):  
Ker C. Thomson ◽  
Thomas J. Ahrens ◽  
M. Nafi Toksöz
Keyword(s):  
Wave Propagation ◽  
High Speed ◽  
Seismic Waves ◽  
Theoretical Calculations ◽  
Body Waves ◽  
S Wave ◽  
S Waves ◽  
Model Study ◽  
Experimental Apparatus ◽  
Fringe Patterns

The occasional existence of very pronounced, anomalous, horizontally polarized seismic waves from underground nuclear bomb blasts has been reported by several investigators. In order to further understanding of this phenomenon and the processes of mechanical radiation from explosions, particularly in prestressed media, a model study has been undertaken. Experimental apparatus has been developed which permits the generation and propagation of body waves from explosions in transparent plate models prestressed to various two‐dimensional stress configurations. High‐speed framing camera sequences are presented showing the explosion process and the resulting plate compressional and shear wave propagation in prestressed models. These are compared to theoretical calculations of isochromatic and [Formula: see text] isoclinic fringe patterns associated with the wave propagation in stressfree plates and plates prestressed in tension and shear. The following distinctive optical phenomena were predicted theoretically and observed in the high‐speed photoelastic patterns: a [Formula: see text] discontinuity between P and S wave isoclinics for the unstressed case; a tendency for the isoclinics to broaden and envelope the isochromatics in regions where the P and S waves are superimposed; development of serrations in the dynamic isoclinics in the presence of a prestressing field (yielding a pseudo‐isochromatic appearance to isoclinics when viewed monochromatically); and finally, a general similarity between the dynamic optical effects in media under tensile and shear prestress.

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