Effect of rock bolt support mechanism on tunnel deformation in jointed rockmass: A numerical approach

Das, Ratan; Singh, T. N.

doi:10.1016/j.undsp.2020.06.001

Cited by 42 publications

(15 citation statements)

References 23 publications

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“…Considering the load bearing capacities of the steel shank bodies of the typical split sets, the active support load of 24 kN can supply 30-40% of the maximum support pressure without a need for rock mass convergences (Thompson and Villaescusa 2014;Salcher and Bertuzzi 2018;Komurlu and Kesimal, 2015;Komurlu et al, 2014). The active support pressure is a remarkable advantage for rock bolts in terms of limitations in the convergences and loosening of the jointed rock masses (Ranjbarnia et al, 2016;Wang et al, 2019;Das et al, 2020) The split-sets are a typical friction type passive rock bolts. It is a novelty for the split-sets to practically supply active support pressure by using the spring plates.…”

Section: Resultsmentioning

confidence: 99%

Improving performances of friction rock bolts by using new spring plates

Komurlu

2021

Bilimsel Madencilik Dergisi

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In this study, a new spring plate was designed and investigated for its usability with the split set type friction bolts. According to the results of this study, remarkable active support pressures can be practically supplied by compression of the new spring plate during the insertion of the split sets. In addition to easy supply of the active support pressure owing to the insertion of the bolts, the energy absorption capacity can be highly improved by use of the new spring plate. Furthermore, the new plate design is remarkably advantageous against the nonaxial loading condition which is very wide in the bolted rock masses.

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Section: Resultsmentioning

confidence: 99%

Improving performances of friction rock bolts by using new spring plates

Komurlu

2021

Bilimsel Madencilik Dergisi

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“…Das and Singh [7] conducted a parametric study to determine the influence of different bolt lengths and bolt diameters on the maximum induced boundary displacements in a jointed rock mass, using a numerical method based on finite element code. The simulation results showed that an increase in the bolt length did not significantly reduce the boundary displacement, whereas an increase in the bolt diameter substantially reduced the tunnel boundary displacement.…”

Section: Causes Of Scale-dependent Behaviormentioning

confidence: 99%

Determination of representative elementary volume (REV) for jointed rock masses exhibiting scale-dependent behavior: a numerical investigation

Sarı

2021

Geo-Engineering

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Representative elementary volume (REV) is defined as the usual size of a rock mass structure beyond which its mechanical properties are homogenous and isotropic, and its behavior can be modeled using the equivalent continuum approach. Determination of REV is a complex problem in rock engineering due to its definition ambiguity and application area. This study is one of the first attempts to define a REV for jointed rock masses using the equivalent continuum approach. It is aimed to numerically search a ratio between the characteristic size of an engineering structure and pre-existing joint spacing, which are the two most important contributing elements in assessing REV. For this purpose, four hypothetical engineering cases were investigated using the RS2 (Phase2 v. 9.0) finite element (FE) analysis program. An underground circular opening with a constant diameter, an open-pit mine with varying bench heights, a single bench with a constant height, and an underground powerhouse cavern with a known dimension were executed for possible changes in the safety factor and total displacement measurements under several joint spacing values. Different cut-off REVs were calculated for FE models depending on the type of excavation and measurement method. An average REV size of 19.0, ranging between a minimum of 2 for tunnels and a maximum of 48 for slopes, was found in numerical analysis. The calculated sizes of REV were significantly larger than the range of values (5 to 10) commonly reported in the relevant geotechnical literature.

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“…And, the strengthening method was proposed to enhance the seismic performance by increasing the mechanical properties of the rock and linings [16]. e rock strengthening method such as grouting and rock bolt can improve the bearing capacity of surrounding rock by reinforcing, so as to avoid tunnel disaster caused by rock instability in earthquake [17,18]. e rock reinforcement plays a significant role in enhancing seismic behavior of the soft rock tunnel causing the properties difference between the linings and surrounding rock.…”

Section: Introductionmentioning

confidence: 99%

Structure Strengthening Method for Enhancing Seismic Behavior of Soft Tunnel Portal Section

Cui

2021

Mathematical Problems in Engineering

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Tunnel portal sections always suffer serious damage under strong earthquakes. This paper aims to study the seismic performance of lining strengthening method in soft rock portal section by employing the model test. Firstly, the shaking table test considering the test cases, the modified input motions, the boundary condition, and monitoring equipment are conducted to simulate the seismic response of the soft tunnel portal section. Then, the lining strengthening method of increasing concrete grade is applied to the tunnel structure to study the aseismic performance of the soft rock tunnel portal section, and the seismic effects of the tunnel linings with different concrete grades are compared and analyzed. The result shows that the proportion of soft rock to total surrounding rock is the key factor affecting the seismic response of soft rock tunnel portal section; the larger the proportion of soft rock in surrounding rock, the more vulnerable the structure to earthquake damage; the seismic performance of the lining strengthening in hard rock portal is remarkable while limited in soft rock portal section. The stiffness and strength of the lining are larger than those of surrounding rock; the seismic performance of the soft portal section could hardly be improved only by the lining strengthening method. It is suggested to adopt both the structure strengthening and isolation method in the seismic design of soft portal section.

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Effect of rock bolt support mechanism on tunnel deformation in jointed rockmass: A numerical approach

Cited by 42 publications

References 23 publications

Improving performances of friction rock bolts by using new spring plates

Improving performances of friction rock bolts by using new spring plates

Determination of representative elementary volume (REV) for jointed rock masses exhibiting scale-dependent behavior: a numerical investigation

Structure Strengthening Method for Enhancing Seismic Behavior of Soft Tunnel Portal Section

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