Damage Evolution Analysis of Rock Slope in Tunnel Entrance Section Under the Seismic Action

Due to the special characteristics of highway tunnels and vehicles, the interior of the tunnel is required to provide appropriate lighting to ensure the safety of driving vehicles, especially at the entrance section of the tunnel. At present, most of the tunnel entrance lighting control system only considers one single factor, the brightness outside the tunnel. However, in practice, the required lighting brightness in the tunnel is also related to traffic flow, speed, and other factors. Comprehensively utilizing these factors to improve the control strategy is urgently needed. To deal with this problem, this article has designed a multi-source information acquisition system for tunnel lighting based on the Internet of things technology, which combined with fuzzy control theory in order to develop an intelligent control system for LED lighting at the entrance section of the tunnel. The designed system was implemented and long-term tested in a real highway tunnel. The experimental results have shown that the system designed in this article can automatically control the brightness of the lighting inside the tunnel according to the real-time measurements of the brightness outside the tunnel, traffic flow, speed, and so on. Furthermore, the utilizations of the system can minimize the human and power consumption of tunnel lighting while ensuring the safety of tunnel traffic.

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Damage evolution analysis of rock under Uniaxial compression and Brazilian splitting based on discrete element method

E3S Web of Conferences ◽

10.1051/e3sconf/202019802018 ◽

2020 ◽

Vol 198 ◽

pp. 02018

Author(s):

Li De-kang ◽

Li Hao-ran ◽

Liu Meng ◽

Wang Zi-heng ◽

Li Zheng

Keyword(s):

Uniaxial Compression ◽

Damage Evolution ◽

Turning Point ◽

Peak Stress ◽

Particle Flow ◽

Evolution Analysis ◽

Simulation Results ◽

Brazilian Splitting ◽

Preloading Method ◽

Compression Condition

In order to better analyze the mechanical behavior of rock in uniaxial compression and Brazilian splitting, numerical model was established according to laboratory test by PFC2D particle flow program, and the simulation results were compared with the experimental results. The results show that when the rock reaches the peak stress, the failure curve of cement appears an obvious turning point, and the failure rate of cement increases.The compressive strength of rock is much greater than the tensile strength under compression condition. The preloading method is more detailed for experimental restoration, and it provides certain reference significance for rock simulation in the future.

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Influence of Ground Motion Parameters on the Seismic Response of an Anchored Rock Slope

Advances in Civil Engineering ◽

10.1155/2020/8825697 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Ningbo Peng ◽

Yun Dong ◽

Ye Zhu ◽

Jie Hong

Keyword(s):

Seismic Response ◽

Axial Force ◽

Seismic Waves ◽

Rock Slope ◽

Dominant Role ◽

Dynamic Responses ◽

Seismic Action ◽

Rock Slopes ◽

Permanent Displacement ◽

Structural Plane

The seismic response of rock slopes is closely related to the dynamic characteristics of earthquakes. In this study, based on a numerical model of rock slopes with bolt support, the seismic responses of both anchored and unanchored rock slopes under different seismic waves are calculated. The results show that a “cumulative effect” of the relative permanent displacement of the slope is generated during seismic action, and it is found that the permanent displacement of the slope is caused by larger earthquake accelerations. The dynamic responses of an anchored slope are analyzed in terms of the wave type, frequency, amplitude, and duration and are compared with those of an unanchored rock slope. This comparison suggests that the nominal shear strain increases with the amplitude and duration, which decreases as frequency increases. The axial force is directly related to the surrounding rock strain. The maximum axial force of the bolt is near the rock interface, which shows that the structural plane of the slope plays a dominant role in the seismic response. The seismic waves are random, whereas the structural plane of the rock slope is certain. The seismic response characteristics of the slope under different earthquake conditions are similar, and the dynamic stability of the slope can be attributed to the structural analysis of the rock slope.

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Meso-damage evolution analysis of magnesium oxychloride cement concrete based on X-CT and grey-level co-occurrence matrix

Construction and Building Materials ◽

10.1016/j.conbuildmat.2020.119373 ◽

2020 ◽

Vol 255 ◽

pp. 119373

Author(s):

Penghui Wang ◽

Hongxia Qiao ◽

Yunsheng Zhang ◽

Yuanke Li ◽

Qiong Feng ◽

...

Keyword(s):

Damage Evolution ◽

Grey Level ◽

Cement Concrete ◽

Evolution Analysis ◽

Magnesium Oxychloride ◽

Magnesium Oxychloride Cement ◽

Occurrence Matrix ◽

Oxychloride Cement

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The Time-Dependent Failure Mechanism of Rocks and Associated Application in Slope Engineering: An Explanation Based on Numerical Investigation

Mathematical Problems in Engineering ◽

10.1155/2020/1680265 ◽

2020 ◽

Vol 2020 ◽

pp. 1-19

Author(s):

Honglei Liu ◽

Lianchong Li ◽

Shaohua Li ◽

Weimin Yang

Keyword(s):

Stress Field ◽

Damage Evolution ◽

Rock Slope ◽

Failure Process ◽

Local Stress ◽

Slope Instability ◽

Time Dependent ◽

Rock Heterogeneity ◽

Local Stress Field

In this study, a numerical model for long-term deformation and progressive failure of rock slope is presented. The model accounts for both rock heterogeneity and the initiation, activation, nucleation, and coalescence of cracks in rock slope through a stochastic local stress field and local rock degradation by using an exponential softening law. The time-dependent behaviour of rocks is taken as a macroscopic consequence of damage evolution and strength degradation in microstructure. A series of demonstrative slope cases containing preexisting joints are constructed and investigated. The slope instability occurs at a particular point in time when the rock strength is reduced to a certain value. The temporal and spatial evolution of joint linkage structures is numerically obtained, which clearly shows how the local stress field and damage evolution within the joint network contribute to the fracture pattern and the long-term instability. Then, a practical slope case in jointed and layered rock formations in Yunyang city is studied. The prevailing failure phenomena of the slope, including gradual surface scaling, sliding collapses, and block falling, are numerically reproduced, with an emphasis placed on the slope failure process and development tendency. There is a good agreement on the failure mode and instability time between the numerical simulations and the field observations.

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Shear Effects on the Anchorage Interfaces and Seismic Responses of a Rock Slope Containing a Weak Layer under Seismic Action

Mathematical Problems in Engineering ◽

10.1155/2020/1424167 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Zhe Long ◽

Zhi-xin Yan ◽

Chun-bo Liu

Keyword(s):

Shear Stress ◽

Rock Slope ◽

Theoretical Research ◽

Amplification Coefficient ◽

Seismic Action ◽

Seismic Responses ◽

Weak Layer ◽

Peak Shear Stress ◽

Shear Effects ◽

Rock And Soil

The shear effects on the anchorage interfaces under seismic action is a key problem requiring urgent investigation in the field of rock and soil anchorages. In this paper, the model of rock slope with a weak layer was constructed by pouring, and the large-scale shaking table model test was completed. The shear strain on the anchorage interfaces and the acceleration of the slope were collected using built measurement systems. The shear effects on the two anchorage interfaces (a bolt-grout interface and a grout-rock interface) and seismic responses of the slope under seismic action were investigated. The distribution laws of the shear stress on the two anchorage interfaces along the axial direction of the bolt under seismic action were gained. The variations of the peak acceleration amplification coefficient on the slope surface, the magnitude, and the growth rate of peak shear stress on the anchorage interfaces under seismic action with different excitation directions and intensities were obtained. Furthermore, the positive relationship between the shear effect on the anchorage interfaces and the seismic response of slope was revealed. This study provides support for theoretical research, numerical simulation analysis, and aseismic design of rock and soil anchorages under dynamic conditions.

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