scholarly journals Effect of Joint Density on Rockburst Proneness of the Elastic-Brittle-Plastic Rock Mass

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jiliang Pan ◽  
Fenhua Ren ◽  
Meifeng Cai
Keyword(s):  
Rock Mass ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Joint Density ◽  
Dissipated Energy ◽  
Uniaxial Compression Test ◽  
Plastic Rock

The prediction of rockburst proneness is the basis of preventing and controlling rockburst disasters in rock engineering. Based on energy theory and damage mechanics, the quantitative functional relationship between joint density and energy density was derived. Then, the theoretical results were verified by numerical simulation and uniaxial compression test, and the effect of joint density on rockburst proneness of the elastic-brittle-plastic rock mass was discussed. The results show that the relationship between the joint density and the dissipated energy index of the jointed rock mass is a logarithmic function. With the same total input energy, the higher the joint density, the more the damage dissipation energy. Even in the case of high joint density, the rock mass still has limited resistance to external failure. Under the same joint density, the strength of parallel jointed rock mass is better than that of the cross-jointed rock mass, and the parallel jointed rock mass can accumulate more elastic strain energy and has higher rockburst proneness. The joint density is closely related to the ability of the rock mass to store high strain energy. The higher the joint density is, the weaker the ability to accumulate the elastic strain energy of rock mass is and the lower the rockburst proneness is. It is helpful to predict rockburst proneness by investigating and studying the properties of geological discontinuities. The research results have some theoretical and engineering guiding significance for the prediction of rockburst proneness of the jointed rock mass.

scholarly journals Stability Analysis of Water-Resistant Strata in Karst Tunnel Based on Releasable Elastic Strain Energy

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Qin Liu ◽  
Lai Wei ◽  
Jianxun Chen ◽  
Yanbin Luo ◽  
Pei Huang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Instability Criterion ◽  
Distribution Law ◽  
Critical Instability ◽  
Concealed Karst Cave ◽  
Rock Mass Failure ◽  
Energy Instability

In this paper, the energy instability criterion of water-resistant strata and rock mass failure index (RMFI) are proposed, respectively, based on releasable elastic strain energy Ue. RMFI is employed to represent the damage extent of water-resistant strata. When RMFI<1.0, rock mass is stable. When RMFI=1.0, rock mass is in the critical instability state. When RMFI>1.0, rock mass is unstable. The releasable elastic strain energy Ue and RMFI program is performed by FISH programming language of Flac3D software. Then, the authors apply Flac3D software to analyze the distribution law of releasable elastic strain energy Ue and failure zone under different width of concealed karst cave. Finally, combined with the numerical analysis, a case study is carried out to illustrate the rationality, effectiveness, and feasibility through using RMFI to predict safe thickness of water-resistant strata.

Numerical Simulation Study on the Delay of Rockburst Based on Rock Mass Stress Release Rate

2014 ◽  
Vol 501-504 ◽  
pp. 20-26 ◽  
Author(s):  
Cheng Lin Yao ◽  
Jie Chen ◽  
Li Peng Liu
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Energy Distribution ◽  
Release Rate ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Simulation Software ◽  
Stress Release ◽  
Shear Field

Rockburst is a phenomenon of geological hazard due to excavation in brittle rockmass of high in-situ stress which endanger to the engineers and construction equipments with unexpectedly damaged. At present, researchers and engineers mainly concentrate to the requirement of rockburst and whether to arise. Although the delay characteristic of rockburst (DCR) has been realized and recorded, but the knowledge of the mechanism of this feature is insufficient. In the paper, the delay characteristic was researched from the stress release rate (SRR) of the excavation rock mass using the numerical simulation software. Firstly, using the core replacement technique, the relation of the SRR and core modulus reduction (CMR) was determined. Secondly, the mechanism of the DCR was analyzed from the elastic strain energy distribution and the plastic strain energy distribution in the different SRR. Finally, the plastic field shape and range under different SRR was contrasted and analyzed. Conclusions can be drawn as follows: with the increase of CMR value, the SRR shows increase trend in the form of exponent. In the process of excavation, the rockmass elastically deform under the low SRR value. When the SRR value equals certain degree, the portion of rockmass will be plastic field and behind the plastic region there will be arise a elastic strain energy centralized phenomenon. Under the different the SRR value, the field style change to the tension-shear field from the shear field in the rock mass and the rockburst rank obviously different.

scholarly journals Multiscale effects caused by the fracturing and fragmentation of rock blocks in rock mass movement: Implications for rock avalanche propagation

2021 ◽  
Author(s):  
Qiwen Lin ◽  
Yufeng Wang ◽  
Yu Xie ◽  
Qiangong Cheng ◽  
Kaifeng Deng
Keyword(s):  
Rock Mass ◽  
Elastic Strain ◽  
Strain Energy ◽  
Mass Movement ◽  
Elastic Strain Energy ◽  
Rock Avalanche ◽  
Strain Energy Release ◽  
Rock Block ◽  
Positive Trend ◽  
Mass System

Abstract. Fracturing and fragmentation of rock blocks are important and universal phenomena during the propagation of rock avalanches. Here, the movement of a rectangular rock block characterized by different joint sets along an upper inclined and lower horizontal traveling path is simulated, aiming to quantify the fracturing and fragmentation effect of the block in propagation. The preset of the joint sets allows the block to break along the weak joint planes at the very beginning of fragmentation. With this design, the fracturing and fragmentation processes in the sliding rock block and their influences on energy transformation in the system are investigated. The results show that fragmentation can alter the horizontal velocities and kinetic energies of fragments in the block system with the front subblocks being accelerated and the rear part being obviously decelerated. Such energy conversion and transfer between the front and rear subblocks is attributed to the elastic strain energy release and transformation caused by fragmentation. The energy transfer induced by fragmentation is more efficient than that induced by collision. A positive trend between the kinetic energy increase of the front subblocks induced by fragmentation and the rock strength can be fitted well with a linear function. However, no good relationship is reached between the strain energy incremental ratio and travel distance, which implies that the fragmentation effects may be weakened with the increasing complexity of the fragmenting rock mass system. Three elastic strain wave release effects caused by rock fragmentation are further inferred and discussed based on simulation results.

Analysis of TBM Tunnel Behavior in Jointed Rock Mass

2011 ◽  
Vol 90-93 ◽  
pp. 2033-2036 ◽  
Author(s):  
Jin Shan Sun ◽  
Hong Jun Guo ◽  
Wen Bo Lu ◽  
Qing Hui Jiang
Keyword(s):  
Rock Mass ◽  
Numerical Models ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Jointed Rock Mass ◽  
Joint Orientation ◽  
Joint Spacing ◽  
Factors Affecting ◽  
Dip Angle

The factors affecting the TBM tunnel behavior in jointed rock mass is investigated. In the numerical models the concrete segment lining of TBM tunnel is concerned, which is simulated as a tube neglecting the segment joint. And the TBM tunnel construction process is simulate considering the excavation and installing of the segment linings. Some cases are analyzed with different joint orientation, joint spacing, joint strength and tunnel depth. The results show that the shape and areas of loosing zones of the tunnel are influenced by the parameters of joint sets and in-situ stress significantly, such as dip angle, spacing, strength, and the in-situ stress statement. And the stress and deformation of the tunnel lining are influenced by the parameters of joint sets and in-situ stress, too.

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