Stability considerations for underground excavation intersections

Gerçek, Hasan

doi:10.1016/s0167-9031(86)90194-5

Cited by 16 publications

(7 citation statements)

References 4 publications

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“…Just like road intersections in traffic engineering, there are also junctions between shafts and roadways in underground mines. For example, the intersection formed by two roadways, the inset connecting a vertical shaft and a pit bottom, as well as the junction between a roadway and a winze used for ore drawing, ventilation, filling, pedestrian passageway, etc [5][6][7]. However, failure of roofs and ribs occurs frequently at intersections due to the large exposed area of surrounding rock, high degree of stress concentration, and strong disturbance caused by multiple times of excavation.…”

Section: Introductionmentioning

confidence: 99%

“…Okubo and Peng [9] found that an arching zone was formed above three-way intersections, and a region of vertical tensile stress was developed over a short distance into the roof. Gerçek [5,10] deemed that the higher the horizontal stress and the more complex the intersection structures, the worse the roof stability at intersections. Hematain [11] proposed two formulas for calculating the bottom radius and the height of dome-shaped roof over four-way intersections.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation on Fracture Evolution in Sandstone Containing an Intersecting Hole under Compression Using DIC Technique

Zhao

Liang

et al. 2019

Advances in Civil Engineering

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Failure of underground structures, especially intersections, becomes more severe as the depth increases, which poses a new challenge for the safe construction and operation of deep rock engineering. To investigate the mechanical properties and fracture behavior of rock with an intersecting hole under compressive loads, a series of uniaxial compression tests was carried out on cuboid red sandstone specimens containing an intersecting hole with three types of shapes by digital image correlation (DIC) technique. The results showed that the existing hole inside specimens leads to almost a 50% reduction of mechanical parameters from that of intact ones, and this weakening effect is associated with the shapes of holes. Failure of specimens is a progressive process in which cracks, i.e., primary tensile cracks, secondary tensile cracks, and shear cracks, initiate from stress concentration zones, propagate along certain direction, and coalesce with each other into macrofractures. Both the real-time principal strain fields and horizontal displacement fields of specimens under compression could be visually displayed by DIC system, and they were in good consistency in characterizing the fracture behavior. Moreover, the propagation characteristics of primary tensile cracks were studied further by quantitatively analyzing the strain variation during the loading process, and the propagation mechanism of “open-close-reopen” of primary tensile cracks was explained in detail.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Fracture Evolution in Sandstone Containing an Intersecting Hole under Compression Using DIC Technique

Zhao

Liang

et al. 2019

Advances in Civil Engineering

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“…Gercek [3], [4] considered that the higher the horizontal stress and the more complex the intersection structure of the roadway, the worse the stability of the roof at the intersection point and the wider the stress superposition area; a dome forms after the roof falls, and the support design of the intersection needs to be intensified and strengthened. Hematain [5] gave formulas for calculating the dome radius, the height of the four-way intersection point, the settlement of the roof and the floor heave at the intersection center point.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Rock With Intersection Structures and its Progressive Failure Mechanism

Luo

et al. 2019

IEEE Access

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To investigate the influence of intersection structures on the mechanical properties and failure mechanisms of rock materials, a series of uniaxial compression tests on complete red sandstone specimens and specimens with various hole shapes (T-shape, cross-shape, and shaft-roadway-shape) were conducted by the Instron 1346 servo-controlled rock mechanics testing machine. Flac3D software and digital image correlation (DIC) were used to simulate the internal stress distribution of rock specimens and reproduce the process of fracture, i.e., cracks initiate, propagate, and coalesce with each other into macroscopic failure under progressive loading. The results show that the intersection structure has a significant weakening effect on the mechanical properties of the rock. The rock strength, elastic modulus, and peak strain of specimens can be ranked as complete specimens > cross-shaped intersection structure specimens > T-shaped intersection structure specimens > shaft-roadway-shaped intersection structure specimens. The energy consumption ratio of the intersection structure specimens before the peak reaches more than 30%, which is approximately twice that of the intact specimens. The brittleness coefficients of the four types of specimens are 0.18, 0.26, 0.21, and 0.20, respectively. The intersection structure specimens induced different degrees of tensile and compressive stress concentration zones on the top and bottom sides of the intersection center point. As a result, initial tensile cracks parallel to the loading direction and shear cracks leading to spalling failure on both sides of the holes were formed. With the increase of the axial stress, secondary tensile cracks extending on the opposite direction appeared at the upper and lower corners of the hole. When the far-field cracks that propagated along the diagonal line coalesced with secondary tensile cracks, macro shear-failure of the specimens appeared. With the increase in axial stress, the principal strain monitored during the fracture process of the specimens gradually increased, then it slowly decreased after the peak. The arched boundary of the T-shaped intersection structure specimen had good stability because of its advantage of suppressing the occurrence of the spalling failure. The shaft-roadway-shaped intersection structure could provide compensation space for the secondary tensile cracks due to the existence of the vertical well. The degree of inhibition of initial tensile cracks was so small that the type of specimens was highly prone to instability or failure.

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“…e station or tunnel section is often constructed through the shaft from the cross passage under the mining method. e stress states and displacements around the conversion section between the shaft and cross passage are three-dimensional [9][10][11]. e surrounding rock masses in the conversion areas are more heavily disturbed than in common tunnels [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Optimal Analysis of Tunnel Construction Methods through Cross Passage from Subway Shaft

Song

Cao

Wang

et al. 2018

Advances in Civil Engineering

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e conversion section of the cross passage and shaft is a priority concern in the stress transformation of a tunnel structure during subway underground excavation. In the construction of Subway Line 5 in Xi'an, China, the main line in the loess layer was constructed through the cross passage from the subway shaft of the Yue Deng Pavilion-San Dian Village Station tunnel section. Numerical simulation and field measurement were adopted to study the construction stability of the cross passage and shaft under two possible construction methods: the "shaft followed by cross passage construction" method and the "cross passage parallel shaft construction" method. e results showed that the surface deformation and plastic zone of the surrounding rock are similar under the two construction methods. However, of the two, the "cross passage parallel shaft construction" method was more advantageous in controlling the structural deformation of the original shaft and the stress distribution of the horsehead structure.e field monitoring data showed that the surface settlements and the deformation of the original shaft structures meet the requirement of control standards under the "cross passage parallel shaft construction" method.

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Stability considerations for underground excavation intersections

Cited by 16 publications

References 4 publications

Experimental Investigation on Fracture Evolution in Sandstone Containing an Intersecting Hole under Compression Using DIC Technique

Experimental Investigation on Fracture Evolution in Sandstone Containing an Intersecting Hole under Compression Using DIC Technique

Mechanical Properties of Rock With Intersection Structures and its Progressive Failure Mechanism

Optimal Analysis of Tunnel Construction Methods through Cross Passage from Subway Shaft

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