Failure Performance of 3DP Physical Twin-Tunnel Model and Corresponding Safety Factor Evaluation

Jiang, Quan; Liu, Xiaopei; Yan, Fengyuan; Yang, Yao; Xu, Di; Feng, Guang-Liang

doi:10.1007/s00603-020-02244-7

Cited by 65 publications

(21 citation statements)

References 66 publications

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“…According to triaxial compression tests of the fractured rock, the progressive failure is often accompanied by the compression, crack, expansion, and mutual intersection of internal fractures [31,32]. e permeability changes obviously with the formation of the fractured networks, owing to the expansion and the penetration of primary cracks.…”

Section: Seepage Characteristics Of the Fractured Rock Massmentioning

confidence: 99%

Seepage Evolution Model of the Fractured Rock Mass under High Seepage Pressure in Dam Foundation

Zhao

Jiang

2021

Advances in Civil Engineering

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The seepage of the fractured rock mass in dam foundations involves complex fluid-structure coupling behavior, due to practical hydrogeological conditions. In this work, the seepage characteristics of the fractured rock mass and their correlations with the structural permeable mediums are experimentally explored to reveal the cracking effect on the hydromechanical properties firstly. Subsequently, the tangential and the compression creep damage constitutive models are, respectively, established by introducing a nonlinear viscoplastic body to improve the Nishihara model. Afterwards, an innovative evolution equation of the permeability coefficient considering the creep damage is proposed. It can indicate the time effect of the porosity, the permeability, and damage variables of the fractured rock mass under the long-term infiltration action of the hydraulic pressures. Ultimately, the proposed methods are applied to the seepage simulation on the dam foundation of the Longyangxia hydropower station and the significantly increased leakage is in good agreement with the measured values during the storage period. It was further confirmed that the crack expansion and penetration in the rock masses can be constantly intensified by the seepage pressures. The research results can provide a reference for engineering repair and supervision through controlling the permeability performance for long-term operations.

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Section: Seepage Characteristics Of the Fractured Rock Massmentioning

confidence: 99%

Seepage Evolution Model of the Fractured Rock Mass under High Seepage Pressure in Dam Foundation

Zhao

Jiang

2021

Advances in Civil Engineering

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“…To explore the effect of the loading and unloading paths on the shear strength, similar with the research about sandstone [24], Figure 5 gives the final failure modes of specimens for LCSG material in the loading and unloading paths. e figure shows that the each specimen has a shear strain band which is the same with the final failure modes of specimens under the typical triaxial tests.…”

Section: Peak Strengthmentioning

confidence: 99%

Experimental Study on Mechanical Behavior of Lean Cemented Sand and Gravel Material in Unloading and Reloading Paths

Yang

Shan

et al. 2021

Advances in Materials Science and Engineering

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Lean cemented sand and gravel (LCSG) materials are subjected to unloading-loading when an LCSG dam is opened for water drainage and then refilled or a roadbed base is subjected to repeated wheel loads. To investigate the behavior of the LCSG materials under loading-unloading, previous studies utilized the complete loading triaxial test. In contrast, in this study, the consolidated drained triaxial tests in the unloading and reloading paths for materials with cementing agent contents of 60 and 100 kg/m3 under different confining pressures, for which each curve generates three loading-unloading cycles, were applied to investigate the unloading and reloading mechanical behavior. Experimental results indicated that the unloading and reloading behavior of the LCSG materials produced stress-strain curves exhibiting a crescent-shaped hysteresis loop, which differs from that exhibited by coarse-grained soil. Although the shape of the crescent-like hysteresis loop was preserved as stress levels increasing, it gradually expanded. Compared with that of the typical triaxial test, the cohesive force and the increasing internal friction angle increased. Further, as the confining pressure increased, the crescent-like hysteresis loops tapered, shear strength increased linearly, and the modulus of resilience increased nonlinearly; the latter’s rate of change, however, decreased. The change in volumetric strain was small during unloading as the stress level changed.

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“…Near the peak stress, there is a horizontal section of axial strain, which represents axial plastic flow. e displacement increase turning point is defined as the ultimate state of structural critical instability [31]. After the plastic flow stage, the deviator stress is greatly attenuated, and the axial compression strain and radial expansion strain increase unambiguously.…”

Section: Lateral Unloading Stress-strain Curve Of Sandstone Atmentioning

confidence: 99%

Mechanical Characteristics of Frozen Sandstone under Lateral Unloading: An Experimental Study

Liu¹,

Yang²,

Dong³

et al. 2021

Advances in Civil Engineering

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The lateral unloading strength and deformation of surrounding frozen rock are the key parameters for safety evaluation of frozen shaft construction. A low-temperature and high-pressure rock triaxial test system was used to simulate freezing construction, and a constant axial pressure unloading confining pressure test was carried out on frozen sandstone. The effects of freezing temperature, initial confining pressure, and unloading rate on the strength, deformation, and failure modes of frozen sandstone are studied. The main results of the study are as follows: (1) under the initial confining pressure of 20 MPa, the temperature of the sandstone decreases from 20°C to –5°C, and the peak stress and elastic modulus of triaxial compression increase by approximately 3 times. Under lateral unloading conditions, the peak stress of frozen sandstone is about 2∼3 times that of 20°C sandstone, and the peak strain of 20°C sandstone is smaller than that of frozen sandstone. The temperature of frozen sandstone decreases and the rate of increase in the peak stress of triaxial compression is slightly less than the rate of increase in the peak stress of lateral unloading. (2) The initial confining pressure of frozen sandstone increases, the growth rate of axial and radial strain increases, the radial strain dominates the failure process, and the lateral unloading strength decreases significantly. (3) The lateral unloading rate of frozen sandstone increases, the peak strength increases, and the axial and radial strain decrease. At a low unloading rate, partial creep deformation occurs. (4) The frozen rock sample undergoes tensile splitting failure under lateral unloading. According to the stress-strain curve of the frozen rock sample, the relationship between changes in the deformation modulus and changes in the confining pressure unloading amount during the unloading process of the rock sample is obtained.

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Failure Performance of 3DP Physical Twin-Tunnel Model and Corresponding Safety Factor Evaluation

Cited by 65 publications

References 66 publications

Seepage Evolution Model of the Fractured Rock Mass under High Seepage Pressure in Dam Foundation

Seepage Evolution Model of the Fractured Rock Mass under High Seepage Pressure in Dam Foundation

Experimental Study on Mechanical Behavior of Lean Cemented Sand and Gravel Material in Unloading and Reloading Paths

Mechanical Characteristics of Frozen Sandstone under Lateral Unloading: An Experimental Study

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