The Influence of the Physical-Mechanical Parameters of Rock on the Extent of the Initial Failure Zone under the Action of an Undercut Anchor

Jonak, Józef; Karpiński, Robert; Wójcik, Andrzej; Siegmund, M.

doi:10.3390/ma14081841

Cited by 27 publications

(34 citation statements)

References 18 publications

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“…This was demonstrated by detailed numerical analyses as well as field investigations by the authors of the study. The present study complements and extends previous analyses conducted by the team of authors of the study, especially [ 31 , 33 , 35 , 36 , 37 , 39 ].…”

Section: Discussionsupporting

confidence: 86%

“…Therefore, the main premise of the research conducted by members of the research team was to determine the tendency of changes in the process of rock destruction, which can be observed during changing physical and mechanical parameters of rocks, parameters of execution of the anchor pull-out process and changes of design parameters of the undercutting head. The paper [ 37 ] analyzed the influence of rock physical-mechanical parameters (Young’s modulus, Poisson’s number, tearing strength) and friction coefficient in the rock-anchor head contact. This paper presents the results of the analysis of the effect of the angle of the undercutting head on the course of the rock structure failure process.…”

Section: Discussionmentioning

confidence: 99%

“…The model takes into account the existence of a potential destruction prism α ( Figure 2 and Figure 3 ). Its value was initially estimated in former analyses [ 31 , 35 , 36 , 37 ]. For such an adopted model of anchor impact on the rock, a finite element mesh model was obtained as in Figure 4 .…”

Section: Methodsmentioning

confidence: 99%

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Influence of the Undercut Anchor Head Angle on the Propagation of the Failure Zone of the Rock Medium

2021

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The paper presents the results of a numerical analysis (FEM) describing the effect of the undercutting head angle on the formation of the rock mass failure zone during the initial stages of failure propagation. The research was carried out in the context of developing a technology for rock extraction by controlled pull-out of undercut anchors installed in the rock mass. The focus was on the initial stage of crack propagation and its trajectory for anchors embedded at an assumed constant depth and a value of the friction coefficient of the rock against the anchor head. It is shown that smaller angles favor smaller stripping angles and an increased radial impact of the head on the rock material (in the plane perpendicular to the head axis), while the impact of heads with larger angles is found to favor larger fracture penetration angles and faster penetration towards the free rock surface.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

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Influence of the Undercut Anchor Head Angle on the Propagation of the Failure Zone of the Rock Medium

2021

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“…Much numerical research has been carried out on the stochastic character of concrete [16][17][18][19][20][21]. Concrete is a primary construction material composed of cement and aggregates and the geometry and distribution of aggregates significantly affect the interface bond performance of the concrete structure.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study on Interface Bond Strength and Anchorage Performance of Steel Bars within Prefabricated Concrete

Shah

Yao

2021

Materials

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This study investigates the interface bond strength and anchorage performance of steel bars within prefabricated concrete. Twenty-two specimens were designed and manufactured to study the interface bond behavior of deformed and plain steel bars under a larger cover thickness. Diameter of steel bars, strength grade of concrete, and anchorage length were considered influential factors. The finite element method (ABAQUS) was used for the validation of experimental results. The interface bond’s failure mechanism and the anchorage length in the prefabricated concrete under different concrete strength levels were explored and compared to national and international codes. A suitable value of the basic anchoring length for the prefabricated structure was recommended. The results show that the interface bond strength of prefabricated bridge members is directly proportional to the strength grade of the concrete, inversely proportional to the reinforcement diameter, and less related to anchorage length. The effect of the cover thickness of the surrounding concrete is negligible. Conversely, the bearing capacity of prefabricated bridge members depends on the strength of the concrete, the diameter of the steel bar, and the anchorage length. Furthermore, it is concluded that the mechanical bond strength accounts for 88% of the bond strength within prefabricated concrete.

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“…However, the work mentioned above refers to minor lap connections. Nevertheless, it is a motivation to explore the present topic by performing numerical analyses [ 27 , 28 ], taking into account the rupture processes at the adhesive–steel interface.…”

Section: Introductionmentioning

confidence: 99%

Influence of Mechanical Properties of Steel and CFRP Tapes on the Effectiveness of Strengthening Thin-Walled Beams

2021

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The paper presents a comparison of the effectiveness of strengthening steel thin-walled, cold-formed sigma beams with CFRP tapes and steel tapes. For this purpose, three beams without reinforcement (reference beams) of the “Blachy Pruszyński” type, with a cross-section of ∑200 × 70 × 2 and a span of 280 cm, made of S350GD steel grade, were subjected to laboratory tests in the four-point bending scheme. In the next stage the tests included nine ∑200 × 70 × 2 beams reinforced with Sika CarboDur S512 CFRP tape and six ∑200 × 70 × 2 beams reinforced with steel tape made of S235 steel grade. The length of the reinforcement tapes as well made of steel as well of CFRP was of 175 cm. The location of the tapes within the height of the beams’ cross-section was assumed in three variants, namely placing the tape on the upper or bottom flange and on the web. In the case of beams reinforced with CFRP, three beams were tested for each reinforcement location, and in the case of beams reinforced with steel tapes, two beams were tested for each reinforcement location. SikaDur®-30 glue with a thickness of 1.3 mm was used in order to connect steel or CFRP tapes to the beams. The dimensions of the tapes cross-sections in both cases were similar (CFRP tapes: 50 × 1.2 mm, steel tapes: 50 × 1.3 mm). For all types of beams, numerical models were also developed in the Abaqus software. The main aim of this paper was investigation of the influence of mechanical properties of steel or CFRP tapes on the effectiveness of strengthening ∑ beams. For this purpose a comparison of these two solutions with respect to the limitation of displacements and deformations of the beam was performed. The obtained results were considered in the context of the mechanical properties of the materials composing the reinforcement tapes. The tests showed slight differences in the results of strain and displacements obtained for reinforcement made of two different materials. It was also noted that the decisive element was the failure of the joint at the steel-glue interface. Therefore, future studies will pay particular attention to the adhesive layer.

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The Influence of the Physical-Mechanical Parameters of Rock on the Extent of the Initial Failure Zone under the Action of an Undercut Anchor

Cited by 27 publications

References 18 publications

Influence of the Undercut Anchor Head Angle on the Propagation of the Failure Zone of the Rock Medium

Influence of the Undercut Anchor Head Angle on the Propagation of the Failure Zone of the Rock Medium

Experimental and Numerical Study on Interface Bond Strength and Anchorage Performance of Steel Bars within Prefabricated Concrete

Influence of Mechanical Properties of Steel and CFRP Tapes on the Effectiveness of Strengthening Thin-Walled Beams

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