Frost-Heaving Cracking Sensitivity of Single-Flaw Rock Mass Based on a Numerical Experimental Method

A novel numerical experimental method is developed herein to study frost-heaving cracking in fractured rock masses by reproducing the physical experimental frost-heaving process. The failure mode of a preexisting closed and water-saturated single-flaw in a rock mass during the frost-heaving process is affected by the inclination angle, flaw width, crack length, and cooling rate. Additionally, a regression model for predicting secondary crack formation and propagation is established by combining multiple stepwise regressions. Overall, the results indicate that preexisting flaw with various inclination angles, flaw lengths, and cooling rates mainly propagates along the flaw-coplanar direction. The secondary crack failure mode is most affected by the flaw width, and the length of the secondary crack increases with increasing inclination angle, flaw width, and flaw length, but decreases with increasing cooling rate. The contributions of the investigated factors to the secondary crack length follow the order: flaw width > inclination angle > cooling rate > flaw length. The results presented herein provide crucial theoretical guidance for engineering and construction projects in cold regions.

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Experimental Study on the Compression Behavior of Grouted Rock with Bi-Directional Penetrating Crack

Applied Sciences ◽

10.3390/app11020537 ◽

2021 ◽

Vol 11 (2) ◽

pp. 537

Author(s):

Han Feng ◽

Xuemin Zhang ◽

Xianshun Zhou ◽

Xuefeng Ou ◽

Cong Zhang ◽

...

Keyword(s):

Compressive Strength ◽

Rock Mass ◽

Failure Mode ◽

Fractured Rock ◽

Compression Tests ◽

Fractured Rock Mass ◽

Compression Behavior ◽

Composite Failure ◽

Excavation Process ◽

Grouting Reinforcement

Grouting is a common method of reinforcing fractured rock mass. The mechanical property of grouted rock is a major aspect of the reinforcement effect, which depends on the geometry of the crack, the angle (β) between the load direction and the crack, and other factors. Few studies have focused on grouted rock with bi-directional crack which can reflect well the grouting reinforcement in the stratum with developed fractures. To explore the grouting effect on fractured rock mass, uniaxial compression tests were carried out on grouted rock samples with different bidirectional widths (t) and angles cracks. The results showed that: (1) when the β was 30°, the failure mode was sliding along the interface of rock and grout, when the β was 45°, the failure mode was composite failure mode, and when the β was 0°, 60°, or 90°, the failure mode was typical intact rock failure mode; (2) when the β increased from 0° to 90°, the uniaxial compressive strength (UCS) decreased and then increased again; (3) when the β was 30°, the UCS had nothing to do with the grout thickness, and when the β was not 30°, the greater the grout thickness, the greater the compressive strength and the ultimate energy storage capacity. The test results can provide reference for grouting reinforcement construction and design in the underground excavation process.

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Damaged Plasticity Theory and its Application in Studying on Fractured Rock

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.105-107.1534 ◽

2011 ◽

Vol 105-107 ◽

pp. 1534-1538

Author(s):

Zhi Qiang Zhang ◽

Ning Li ◽

Fang Fang Chen

Keyword(s):

Rock Mass ◽

Numerical Model ◽

Failure Mode ◽

Fractured Rock ◽

Jointed Rock ◽

Plasticity Theory ◽

Constitutive Relationship ◽

Fractured Rock Mass ◽

Lab Experiments ◽

Initiation And Propagation

Fractured rock mass is one of the most important engineering materials for civil engineering in rock mass and rock layer, and has special failure model and constitutive relationship different from other man-made materials. A new numerical model is introduced and applied in studying the deformation, strength, and the failure mode of fractured rock mass, with the consideration of the damaged plasticity theory for intact rock, and joints distribution in fractured rock mass. A series of numerical experiments on jointed rock mass samples are performed to verify the validity of the new numerical model for fractured rock sample. Some feature datum from lab experiment is used to compare the results from numerical tests by the new model. According to these results, the initiation and propagation of induced fracture, and the failure mode of the fractured rock mass samples, are agreed with their associated feature datum by lab experiments.

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The effects of hydro-mechanical coupling on hydraulic properties of fractured rock mass in unidirectional and radial flow configurations

Geomechanics and Geophysics for Geo-Energy and Geo-Resources ◽

10.1007/s40948-021-00286-x ◽

2021 ◽

Vol 7 (3) ◽

Author(s):

Wei Li ◽

Zhechao Wang ◽

Liping Qiao ◽

Jie Liu ◽

Jinjin Yang

Keyword(s):

Rock Mass ◽

Hydraulic Properties ◽

Radial Flow ◽

Fractured Rock ◽

Fractured Rock Mass ◽

Mechanical Coupling ◽

Flow Configurations

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Analysis of Unstable Rock-Mass Stability Based on Limit Equilibrium Method and Strength Reduction Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.858.73 ◽

2016 ◽

Vol 858 ◽

pp. 73-80

Author(s):

Ying Kong ◽

Hua Peng Shi ◽

Hong Ming Yu

Keyword(s):

Rock Mass ◽

Failure Mode ◽

Posterior Margin ◽

Reduction Method ◽

Limit Equilibrium ◽

Limit Equilibrium Method ◽

Strength Reduction ◽

Strength Reduction Method ◽

Rock Masses ◽

Unstable Rock

With the slope unstable rock masses of a stope in Longsi mine, Jiaozuo City, China as the target, we computed and analyzed the stability of unstable rock masses using a limit equilibrium method (LEM) and a discrete element strength reduction method (SRM). Results show that the unstable rock masses are currently stable. Under the external actions of natural weathering, rainfall and earthquake, unstable rock mass 1 was manifested as a shear slip failure mode, and its stability was controlled jointly by bedding-plane and posterior-margin steep inclined joints. In comparison, unstable rock mass 2 was manifested as a tensile-crack toppling failure mode, and its stability was controlled by the perforation of posterior-margin joints. From the results of the 2 methods we find the safety factor determined from SRM is larger, but not significantly, than that from LEM, and SRM can simulate the progressive failure process of unstable rock masses. SRM also provides information about forces and deformation (e.g. stress-strain, and displacement) and more efficiently visualizes the parts at the slope that are susceptible to instability, suggesting SRM can be used as a supplementation of LEM.

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Fracture System and Rock-Mass Characterization by Borehole Camera Surveying: Application in Dimension Stone Investigations in Geologically Complex Structures

Applied Sciences ◽

10.3390/app11020764 ◽

2021 ◽

Vol 11 (2) ◽

pp. 764

Author(s):

Ivica Pavičić ◽

Ivo Galić ◽

Mišo Kucelj ◽

Ivan Dragičević

Keyword(s):

Rock Mass ◽

Fractured Rock ◽

Low Cost ◽

Fracture Pattern ◽

Dimension Stone ◽

Rock Mass Characterization ◽

Size And Shape ◽

Distribution Parameters ◽

Borehole Camera ◽

Fracture Distribution

The successful exploration of dimension stone mainly depends on the quality, size, and shape of extractable blocks of dimension stone. The investigated area is in the Pelješac Peninsula (Croatia), in the External Dinarides orogeny, built from thick carbonate succession, characterized by relatively small deposits of high-quality dimension stone. These conditions demand challenging geological investigations in the “pre-quarry” phase to find optimal quarry location. The size and shape of dimension stone blocks are mainly controlled by fracture pattern systems. In the rugged, covered terrains, it is very hard to obtain a satisfactory amount of fracture data from the surface, so it is necessary to collect them from the underground. Borehole camera technology can visualize the inner part of the rock mass and measure the fracture characteristics. The main conclusions are as follows: (1) the digital borehole camera technology provides a quick, effective, and low-cost geological survey of fractured rock mass; (2) statistical fracture distribution parameters, P10, fracture spacing, Volumetric Joint Count (Jv) based on borehole wall survey can reflect the integrity of rock mass, providing a solid decision-making base for further investment plans and dimension stone excavation method.

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