Assessment of long-term deformation of a tunnel in soft rock by utilizing particle swarm optimized neural network

Kovačević, Meho Saša; Bačić, Mario; Gavin, Kenneth; Stipanović, Irina

doi:10.1016/j.tust.2021.103838

Cited by 31 publications

(11 citation statements)

References 50 publications

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“…Applying Burger's model to FEM, Fahimifar et al [11] studied the analytical solution of a viscoelastic circular tunnel under hydrostatic pressure. Meho et al [13] evaluated the long-term deformation characteristics of soft rock in an efficient way by using an improved Burger's model in finite element neural network simulation, and the results agree well with the experimental results. Then, applying Burger's model into DEM, Li et al [14] studied the rheological behavior of soft rock; Guo et al [15] studied the time-dependent mechanics of sandstone.…”

Section: Introductionmentioning

confidence: 70%

Burger’s Bonded Model for Distinct Element Simulation of the Multi-Factor Full Creep Process of Soft Rock

Xia

Liu

Zhou

2021

JMSE

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Pervasive, unavoidable and uncontrollable creep failure generated in soft-rock engineering occasionally happens and therefore attracts extensive attention recently. However, due to soft rock’s multi-factor creep mechanism, it is still difficult to simulate the full-stage creep with the Distinct Element Method (DEM). In this study, we proposed an improved simulation method based on the classical Burger’s model and the Parallel Bonded model in Particle Flow Code (PFC). We apply the abovementioned models together to simulate the full-stage creep process in soft rock. The proposed process has considered the mesoscopic mechanical characteristics of DEM carefully and finally resulted in a parallel physical model, which is called Burger’s Bonded model in this paper. The DEM simulation test using Burger’s Bonded model was designed to compare with experiments. The experiments include a normal creep test and a uniaxial loading test with prefabricated cracks. In contrast to experimental results, the numerical results show that the average error during the whole creep process is less than 3%; the stress–strain curves and crack development process show great agreement. It is also found that the wing crack coalescence in soft rock is independent of the prefabricated crack angle, propagating with a fixed dip angle. The results show that the numerical method proposed in this paper can simulate the multi-factor-caused full stage (attenuated, steady, accelerated) creep process of soft rock in DEM, which provides new insights for theoretical research and engineering design.

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Section: Introductionmentioning

confidence: 70%

Burger’s Bonded Model for Distinct Element Simulation of the Multi-Factor Full Creep Process of Soft Rock

Xia

Liu

Zhou

2021

JMSE

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“…A significant number of engineering applications and laboratory studies indicated the mechanical response related to weak and soft rock's time-dependent behavior is relatively complicated (Zhu et al 2020;Yan et al 2020;To ¨ro ¨k et al 2019;Singh et al 2018;Patil et al 2018;Vlastelica et al 2018;Lyu et al 2017;Gu ¨nther et al 2015; Mis ˇc ˇevic ´and Vlastelica 2014; Zhou et al 2014). One of the significant parameters affecting the underground spaces' longterm stability is weak rock mass creep response (Kovac ˇevic ´et al 2021;Panthi and Shrestha 2018). In addition, underground water as an important environmental component influences weak rock's short-term and long-term behavior, especially in fault and karst regions (Verbovs ˇek and Kanduc ˇ2016).…”

Section: Introductionmentioning

confidence: 99%

Long-term assessment of creep and water effects on tunnel lining loads in weak rocks using displacement-based direct back analysis: an example from northwest of Iran

Tarifard

Görög

Török

2022

Geomech. Geophys. Geo-energ. Geo-resour.

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The time-dependent stability of tunnels is an important and challenging topic, mainly when the tunnel is excavated in incompetent and weak rocks. The creep property of rock is one of the crucial mechanical properties of weak rock and the main factor affecting the long-term stability of rock masses. Also, water as an important environmental factor influences both the short-term and long-term behavior of rocks and is one of the causes of geotechnical engineering disasters, such as tunnel collapse, slope sliding, surface subsidence, etc. In this research, the effects of rock’s creep behavior and underground water on the long-term stability of the Shibli tunnels were analyzed. Geological maps and reports of Shibli tunnels show a highly jointed condition in the surrounding rocks which have been crushed by two orogenic stages. The Burger-creep visco-plastic model was used to simulate the tunnel host rock creep behavior. The model's parameters were adopted based on the displacement-based direct back analysis technique using a univariate optimization algorithm. In addition, the influence of underground water is assessed under the condition of the varying water table. Support capability diagrams were used to evaluate the loading created on the tunnel’s permanent lining due to the creep behavior of rock mass and underground water. This study suggests that the weak rock's creep behavior and underground water significantly affect the time-dependent stability of tunnels. Results show that the induced stresses due to the rock's creep behavior and underground water are more considerable in the tunnel spring-line. Also, the increasing 20 m in the water table approximately decreases ten years of tunnel lining stability time at the fault zone. Article highlights Rocks creep behavior and underground water significantly affect the time-dependent stability of tunnels in weak rocks. Displacement-based direct back analysis using a univariate optimization algorithm was used to determine the CVISC model’s properties. Increasing 20 m in the water table approximately decreases ten years of tunnel lining stability time at the fault zone.

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“…Ma et al (2021) found that tunnel-collapse accidents caused by improper control of the surrounding rock stress release, high ground stress, and discontinuity often occur in the construction process of soft rock tunnels, causing significant losses to the corresponding projects. A Kovacevic et al (2021) and Cheng et al (2018) found that to ensure the construction safety in a soft rock tunnel with high geo-stress and the stability and durability of the tunnel, it is necessary to initially study the deformation laws of the rock mass. At present, the control and monitoring processes for tunnel rock mass deformations are mainly concentrated on the surrounding rock of the excavated part.…”

Section: Introductionmentioning

confidence: 99%

Model test study on the rock mass deformation law of a soft rock tunnel under different ground stresses

et al. 2022

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It is difficult to monitor the deformation of a rock mass in front of a tunnel owing to the large buried depth and complex geological conditions. In this study, by using a self-designed model test box as a carrier and using loess, sand, gypsum, cement, and water as the raw materials, the class V materials similar to the surrounding rock are obtained through an orthogonal test. These are used to study the deformation law of a rock mass in front of a tunnel in different ground stress soft rock. The results show that similar materials for the surrounding rock can meet the needs of the testing concerning the physical and mechanical properties and have economic and environmental protection advantages. The three-dimensional loading of a similar geological body is used to simulate the state of the rock mass. The real-time monitoring of the rock mass stress and deformation is conducted during a simulation of tunnel excavation, and the deformation laws of the rock mass and surrounding rock in front of the tunnel are obtained. In the range of 0.26 times the tunnel diameter in front of the tunnel in the high ground stress soft rock, the deformation of the core rock mass is the largest part of the tunnel deformation. Therefore, to reasonably control the advanced deformation of the tunnel, it is necessary to pre-reinforce the core rock mass within 0.26 times the tunnel diameter in front of the tunnel. At 1 times the diameter in front of the face, a longitudinal load-bearing arch is formed in the rock mass, and this effectively controls the extrusion deformation of the core rock mass to expand forward.

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Assessment of long-term deformation of a tunnel in soft rock by utilizing particle swarm optimized neural network

Cited by 31 publications

References 50 publications

Burger’s Bonded Model for Distinct Element Simulation of the Multi-Factor Full Creep Process of Soft Rock

Burger’s Bonded Model for Distinct Element Simulation of the Multi-Factor Full Creep Process of Soft Rock

Long-term assessment of creep and water effects on tunnel lining loads in weak rocks using displacement-based direct back analysis: an example from northwest of Iran

Model test study on the rock mass deformation law of a soft rock tunnel under different ground stresses

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