Experimental investigation on rockburst process and failure characteristics in trapezoidal tunnel under different lateral stresses

Zhao, Hongbao; Liu, Chao; Huang, Gun; Yu, Beichen; Liu, Yubing

doi:10.1016/j.conbuildmat.2020.119530

Cited by 42 publications

(20 citation statements)

References 40 publications

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“…Generally, shear fracture, tensile fracture and mixed shear fracture and tensile fracture are the common fracture modes during rock failure, and we can identify these fracture modes depending on the AE signals induced by the initiation and propagation of different types of cracks [ 35 ]. Thus, the ratio of the average frequency value (i.e., AF) to the rise angle value (i.e., RA) was proposed to identify the failure modes [ 23 , 34 , 36 , 37 ].…”

Section: Results and Analysismentioning

confidence: 99%

“…According to the published results [ 23 ], we obtained the accurate value of AF/RA used to characterize the tensile fractures and shear fractures by conducting the Brazilian split tests and direct shear tests. Based on the test results, the value of AF/RA was defined as 60 to distinguish the mode of fractures.…”

Section: Results and Analysismentioning

confidence: 99%

“…A newly developed multifunctional true triaxial (TTG) apparatus was applied to conduct the biaxial compression tests in this study [ 23 , 25 ]. A maximum force of 6000 kN in two directions can be loaded to the rock specimen and the maximum force which can be applied in another direction is 4000 kN.…”

Section: Experimental Methodologymentioning

confidence: 99%

“…However, the shape of tunnel is not only circular, but also elliptical, square, inverted U-shaped and so on. The influence of opening shape on the mechanics, failure characteristics, stress concentration and fracture patterns of rocks has been demonstrated [ 17 – 23 ]. The fracturing processes around the circular, elliptical and inverted U-shaped openings were shown by using RFPA [ 17 ] and the influence of lateral pressure coefficients were considered.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress

et al. 2021

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Two kinds of common tunnel shapes, i.e. elliptical opening and square opening were selected for biaxial compression tests, and the influences of two kinds of opening shapes on the mechanical properties, failure characteristics and failure modes of sandstone were compared and analyzed. The complex variable theory and mapping functions were used to obtain the analytical stress solution around elliptical and square openings. The results show that the stability of the specimen containing an elliptical opening was better than that of the specimen containing a square opening under the same lateral stress. Compared with the elliptical opening, the local damage was formed earlier in the square opening which might be caused by a higher stress concentration around the square opening. The stress distributions around openings were influenced by the opening shape and lateral stress coefficient. The top and bottom of square opening were more prone to tensile fracture, and the distribution range of tensile was larger than that of elliptical opening. When the opening failed, the intensity of square opening failure was weaker than that of elliptical opening. On the basis of the average frequency value and the rise angle value, the failure mode of specimen containing elliptical or square opening was distinguished. It was found that the mixed tension and shear failure dominated the failure of specimens with different opening shapes, and the number of shear cracks in the specimen containing a square opening was greater than that in the specimen containing an elliptical opening. The above method of judging failure mode by acoustic emission signals was well verified by the CT images of damaged specimens.

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Section: Results and Analysismentioning

confidence: 99%

Section: Results and Analysismentioning

confidence: 99%

Section: Experimental Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress

et al. 2021

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“…Su et al [8] found that, after the ejection failure of coarse-grained granite samples, V-shaped or stepped rockburst pits were formed. Zhao et al [9] carried out biaxial compression tests on sandstone samples with trapezoidal opening. It was found that the failure zones on both sides of the trapezoidal opening were V-shaped under different lateral compressive stress regimes.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Formation of Rockburst Pits in Circular Tunnel Based on CT Scanning

Zhang

Yao

Sun

et al. 2020

Advances in Civil Engineering

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The rockburst simulation experiments of granite samples with a circular hole under biaxial loading were conducted, and the samples were scanned by computed tomography (CT) at the end of experiment. Through a series of CT images, the failure characteristics of the circular hole wall were analysed to determine the types of rockburst pits, and the detailed formation process of different types of rockburst pits was studied in combination with the crack characteristics around them. The experimental results indicate that there are mainly two types of rockburst pits, namely, pan-shaped and V-shaped, which can occur symmetrically or asymmetrically on the left and right sidewall of the circular hole. The formation of rockburst pits is related to the cracks parallel and perpendicular to the principal stress. Cracks parallel to the principal stress can determine the depth of the rockburst pit and affect the type of the rockburst pit, and cracks perpendicular to the principal stress determine the width of the rockburst pit. There is a correlation between the formation process of pan and V-shaped rockburst pits. During the formation of a V-shaped rockburst pit, several rockbursts occur, and each rockburst forms a pan-shaped rockburst pit. In the process of developing from the tunnel wall to the deep rock, the width of the pan-shaped rockburst pit gradually decreases and a V-shaped rockburst with a stepped upper and lower boundary is formed.

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Fracture evolution characteristics of strainburst under different gradient stress

Wang,

Liu,

Song

et al. 2023

Num Anal Meth Geomechanics

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Strainburst often occurs in the loading process of tangential stress concentration from surrounding rocks after excavation and unloading of deep rock mass. The concentrated tangential stress is relatively larger on the tunnel walls, which decreases towards the interior of surrounding rocks with a certain gradient. To explore the fracture evolution characteristics of surrounding rocks under different tangential gradient stresses and understand various phenomena in the strainburst process, a large‐scale true‐triaxial gradient and hydraulic‐pneumatic composite loading rockburst test device was adopted to carry out the strainburst tests under four different gradient stresses. Based on the macroscopic failure phenomena, distribution of rockburst debris, macro‐micro morphology of failure cross section, and monitored data of acoustic emission (AE), the fracture evolution of rockburst specimens was analyzed under different stress gradient loadings. The results indicate that the stress gradient has an obvious influence on the fracture characteristics, resulting in different rockburst phenomena. With the increase of stress gradient, the failure stress of rockburst decreases, while the dynamic failure characteristics of rockburst trends to be significant. The increase of stress gradient contributes to higher fragmentation degree of debris, more uniform distribution and better continuity. The total number of cracks in the model decreases with the rise of the stress gradient, and the proportion of shear failure increases, which is the main reason for the enhancement of the rockburst intensity.

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Experimental investigation on rockburst process and failure characteristics in trapezoidal tunnel under different lateral stresses

Cited by 42 publications

References 40 publications

Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress

Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress

Experimental Investigation of the Formation of Rockburst Pits in Circular Tunnel Based on CT Scanning

Fracture evolution characteristics of strainburst under different gradient stress

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