Simulation on Freeze-Thaw Action in Multi-Cracks in Rock Mass

Freeze-thaw action in fractured rock mass is discussed. Moist rock exposed to subfreezing temperature would suffer from freeze-thaw deterioration, which would pose serious threat to the stability of geotechnical engineering. Some key factors influencing freeze-thaw action in rock mass is analyzed, such as temperature, freezing rate, freeze-thaw cycles and porosity of the rock. Further more, using the theory of physical chemistry, the freezing point and frozen ratio were derived. Finally, the model of frost crack was built by ANSYS and then imported into FLAC3D by converting procedure. The stress field, temperature filed as well as the normal and shear stress on surface of the cracks were demonstrated. The effect of freezing pressure is reflected in the results.

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Transient Analysis of Grout Penetration With Time-Dependent Viscosity Inside 3D Fractured Rock Mass by Unified Pipe-Network Method

Water ◽

10.3390/w10091122 ◽

2018 ◽

Vol 10 (9) ◽

pp. 1122 ◽

Cited By ~ 6

Author(s):

Zizheng Sun ◽

Xiao Yan ◽

Rentai Liu ◽

Zhenhao Xu ◽

Shucai Li ◽

...

Keyword(s):

Rock Mass ◽

Large Scale ◽

High Efficiency ◽

Fractured Rock ◽

Time Dependent ◽

Pipe Network ◽

Fractured Rock Mass ◽

Network Method ◽

The Stability ◽

Dependent Viscosity

Grouting is widely used for mitigating the seepage of underground water and enhancing the stability of fractured rock mass. After injection, the viscosity of the grout gradually increases until solidification. Conventional multifield analysis models ignoring such effects greatly overestimate the penetration region of the grout and the stability of the grouted rock structures. Based on the 3D unified pipe-network method (UPM), we propose a novel numerical model considering the time-dependent viscosity of the grout, therein being a quasi-implicit approach of high efficiency. The proposed model is verified by comparing with analytical results and a time-wise method. Several large-scale 3D examples of fractured rock mass are considered in the numerical studies, demonstrating the effectiveness and robustness of the proposed method. The influence of the time-dependent viscosity, fracture properties, and grouting operation methods are discussed for the grout penetration process.

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Stability Analysis of Dangerous Rocks on the Slope of a Hydropower Station

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.405-408.621 ◽

2013 ◽

Vol 405-408 ◽

pp. 621-629 ◽

Cited By ~ 1

Author(s):

Hai Feng Li ◽

Guo Xing Zhang ◽

Tao Huang ◽

Qiu Jing Zhou

Keyword(s):

Rock Mass ◽

Fractured Rock ◽

Discontinuous Deformation Analysis ◽

Hydropower Station ◽

Deformation Analysis ◽

Time Interval ◽

Block Method ◽

Fractured Rock Mass ◽

Unstable Failure ◽

The Stability

Dangerous rocks are among the most significant factors in analyzing the stability of high slopes, and are the main geological hazards on such slopes. These rocks are typical spatial blocks. The unstable failure of dangerous rocks poses evident spatial features. Consequently, their stability should be calculated by considering it as a three-dimensional (3-D) problem. In this research, the general block method of fractured rock mass and 3-D discontinuous deformation analysis (DDA) are used to study the stability of dangerous rocks on the slope of a hydropower station. The general block method of fractured rock mass is used to generate dangerous rocks and to assess the geometric mobility of blocks. The progressive unstable failure of dangerous rocks is also analyzed. Moreover, 3-D DDA is implemented to examine the stability of dangerous rocks, including the regularity of their unstable failure. The failure sequence of each batch of blocks estimated by general block theory is the same as that in the results of 3-D DDA. The decrease in the shear parameters of the structural plane shortens the time interval of failures, but increases the number and capacity of blocks.

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The importance of pre-tensioning cable bolts used to reinforce of arch yielding support

E3S Web of Conferences ◽

10.1051/e3sconf/20186603003 ◽

2018 ◽

Vol 66 ◽

pp. 03003

Author(s):

Zbigniew Rak ◽

Jerzy Cieślik ◽

Jerzy Stasica ◽

Pavel Dvořák

Keyword(s):

Rock Mass ◽

Fractured Rock ◽

Hard Coal ◽

The Finite Element Method ◽

Fractured Rock Mass ◽

Cable Bolts ◽

Vertical Displacements ◽

Hard Coal Mining ◽

The Stability ◽

Yielding Support

Widespread in Polish hard coal mining, cable bolts are used to reinforce the arch yielding support of roadways. This article attempts to prove that change in approach to long bolting technology can bring significant benefits in terms of improving the stability of roadways, including limiting the development of the fracturing zone in the roof, and ultimately also increasing the frame spacing of arch yielding support. The article contains the results of numerical calculations using the finite element method showing the effect of pre-tensioning on the work of cable bolts installed in a situation when a zone of a fractured rock mass appeared in a roof excavation. As a result of the calculations, the dependence of the final vertical displacements of the roadways roof on different pre-tensioning variants of the cable bolts was presented. The second part of the article presents the practical aspects of the use of cable bolts with pre-tensioning in reinforcing the rock mass and arch yielding support of roadways. In addition, the article identifies the developments in bolting technology which could lead to an increase in work safety and reduce the costs of arch yielding support.

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