Classification of Factors Affecting the Performance of Fully Grouted Rock Bolts with Empirical Classification Systems

Kim, Haneol; Rehman, Hamood Ur; Ali, Wahid; Naji, Abdul Muntaqim; Kim, Jung-Joo; Kim, Jonguk; Yoo, Hee Koo

doi:10.3390/app9224781

Cited by 16 publications

(8 citation statements)

References 35 publications

(66 reference statements)

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“…In the grout mix, the water to cement ratio was 0.45 by weight. In rock bolting, typical water to cement ratios of grout mixes vary between 0.35 and 0.45 by weight [14][15][16][17]. There were five different grout mix groups with no polymer, 3.5% and 7.0% polymer (SMS and MS Polymer) additives by weight.…”

Section: Methodsmentioning

confidence: 99%

An Investigation of Using Thermoset Polymer Type Liquid Additives to Improve Cement Grout Performances in Rock Bolting Applications

Komurlu

2020

Int. J. of Geosynth. and Ground Eng.

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Effect of thermoset type polymeric additives on load-bearing capacities of grouted rock bolts was investigated with both laboratory and site studies. For the specimen preparation, two different silicone-based polymeric materials were added with different amounts in the cement and water mixes. Additionally, cement grouts without the polymeric additive were also used to compare results obtained from different grout usage cases. The additives are in the liquid phase while adding into the fresh cement mix and start to solidify due to the polymerization after being mixed in the grout material. Support performances of various grouted rock bolt specimens were tested under axial and shear loading conditions. According to the results of this study, use of the polymeric additives with an amount of 3.5% by weight in total mix significantly improves the ductility in support reactions of grouted bolts and increases the energy absorption capacity by high rates over 50%.

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Section: Methodsmentioning

confidence: 99%

An Investigation of Using Thermoset Polymer Type Liquid Additives to Improve Cement Grout Performances in Rock Bolting Applications

Komurlu

2020

Int. J. of Geosynth. and Ground Eng.

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“…In this approach, the thickness of shotcrete and spacing of the rock bolt were applied with the tunnel span in the support chart for the RMR and Q systems. In tunnel composite support, the contribution of the rock bolt and shotcrete to the support are different, owing to numerous factors; therefore, no criterion is available for choosing rock-bolt-spacing-based rock mass quality (Q2*and RMR2*) and shotcrete thickness, along with tunnel-span-based rock mass quality (Q1*and RMR1*) weightage for the back calculation [71]. Therefore, five cases were chosen, and Table 6 lists the details [72].…”

Section: Generalmentioning

confidence: 99%

Impact of Construction Method and Ground Composition on Headrace Tunnel Stability in the Neelum–Jhelum Hydroelectric Project: A Case Study Review from Pakistan

et al. 2021

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During underground construction, the behavior of the ground is influenced by characteristics of the rock mass with situ stresses and ground water, cross section of the excavation area, excavation method, and the rate of excavation. These fundamental features are considered to ensure the support and stability of underground excavations and achieve long-term successful operation. However, the ground composition of the Himalayas hinders tunnel excavation, especially in case of mechanized tunneling; this causes time and cost overruns. This study has reviewed the recently completed Neelum–Jhelum Hydroelectric Project; the project complexities, geological environments involving significant overburden and tectonic stresses, and effects of the excavation method on tunnel stability were analyzed. The major challenges that were encountered during construction are discussed herein along with their countermeasures. An analysis of project-related data reveals that latest techniques and approaches considering rock mechanics were used to complete the project; the existing approaches and methods were accordingly verified and extended. Apart from ground composition, the excavation methods used play an important role in the occurrence of severe rock bursts. Thus, the findings of this study are expected to be helpful for future tunneling projects in the Himalayas.

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“…Therefore, for projects in urban areas, a soil nail-prestressed anchor composite retaining structure is preferable. This is because the additional prestressed anchors can assist, in addition to the soil nails, to limit the displacement of the slope surface [12][13][14][15]. A typical layout of the soil nail-prestressed anchor composite retaining structure is shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Full-Scale Field Test on Construction Mechanical Behaviors of Retaining Structure Enhanced with Soil Nails and Prestressed Anchors

Wang

Cheng

et al. 2021

Applied Sciences

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Soil nailing combined with prestressed anchors has a good workability and is relatively cheap in constraining the horizontal displacement. Current research on the technique, whether theoretical analyses, numerical simulations, or model tests, was conducted under ideal working conditions. However, in fact, external disturbances, such as tensioning-lagging of the anchor, are very common and play an important role on stress and displacement. Therefore, it is of great significance to carry out a field test considering the effects of external disturbances, which can obtain real and reliable data through real-time monitoring. In this paper, the impacts of the construction conditions on practical engineering are discussed based on in situ tests, and some reasonable suggestions for the upgrading of misbehaviors in the current construction situation are put forward. In particular, the influence features of soil predisturbance, excessive excavation, unloading on the surface of edges, tensioning-lagging of the anchor, and continuous rainfall on the stress–time curve of soil nails under practical working conditions are analyzed. Behaviors of three different retaining structures enhanced with (i) soil nails; (ii) soil nails and prestressed anchors without unbonded parts; and (iii) soil nails and prestressed anchors with a 2.5 m unbonded part were monitored during staged excavation to investigate the influences of (i) the prestressing force and (ii) the unbonded part of the prestressed anchors on the performance of the entire retaining system. Results show that (i) the prestressing force is the main factor affecting the stress and deformation of the composite retaining system, which is consistent with the existing literature; (ii) the variation of the magnitude and distribution of the soil nail force responding to the anchor prestressing force, however, showed no systematic trend; and (iii) the unbonded part of anchors, which was validated to be the main factor affecting the structural stability in dense materials in the existing literature, is found to have a minor influence in loose fill materials used in this study.

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Classification of Factors Affecting the Performance of Fully Grouted Rock Bolts with Empirical Classification Systems

Cited by 16 publications

References 35 publications

An Investigation of Using Thermoset Polymer Type Liquid Additives to Improve Cement Grout Performances in Rock Bolting Applications

An Investigation of Using Thermoset Polymer Type Liquid Additives to Improve Cement Grout Performances in Rock Bolting Applications

Impact of Construction Method and Ground Composition on Headrace Tunnel Stability in the Neelum–Jhelum Hydroelectric Project: A Case Study Review from Pakistan

Full-Scale Field Test on Construction Mechanical Behaviors of Retaining Structure Enhanced with Soil Nails and Prestressed Anchors

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