scholarly journals Investigation of Load Bearing Capacities of Grouted Rock Bolts with New Auxetic Head Designs

2020 ◽  
Author(s):  
Eren Komurlu ◽  
Aysegul Durmus Demir ◽  
Atila Gurhan Celik
Keyword(s):  
Numerical Modelling ◽  
Energy Absorption ◽  
Experimental Studies ◽  
Head Part ◽  
Rock Bolts ◽  
Load Bearing ◽  
Ratio Effect ◽  
Pull Out ◽  
Drill Holes ◽  
Grouted Rock Bolts

Within this study, new bolt heads were designed to be able to expand in drill holes as the load applied on the bolt shank increases. The heads of newly designed rock bolts include a conic part and split rings encircling them. To determine load bearing capacities of new rock bolts with varying angles of the conic parts and expansion properties, a series of deformation controlled pull-out tests were carried out by using bolt samples grouted in rock blocks. In addition to the experimental studies, numerical modelling analyses were performed to better understand the support properties of newly designed rock bolts. Because of a negative Poisson’s ratio effect supplied by the head part expansion with the tension of the shank, new bolt heads are suggested to be defined as auxetic. According to the results of this study, the new head designs significantly improve the load bearing and energy absorption capacities of grouted rock bolts.

scholarly journals Length Effect on Load Bearing Capacities of Friction Rock Bolts

2019 ◽  
Author(s):  
Eren Komurlu ◽  
Serhat Demir
Keyword(s):  
Numerical Modelling ◽  
Bearing Capacity ◽  
Experimental Studies ◽  
Rock Bolt ◽  
Rock Bolts ◽  
Length Effect ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Pull Out ◽  
Modelling Study

Change in the load bearing capacity of the split set type friction rock bolts with variations of bolt lengths was investigated within this study. To determine a relation between the load bearing capacity and bolt length parameters, different friction bolt models with various lengths were analyzed with a numerical modelling study. In addition, a series of pull-out tests was carried out to evaluate the load bearing capacities of the split set type friction rock bolts with different lengths. The load bearing capacity of the bolts was found to decreasingly increase with the increase in the bolt length. As an outcome of this study, a relation between the load bearing capacity and rock bolt length parameters is suggested in accordance with the results obtained from both numerical and experimental studies.

The Performance of Axially Loaded, Fully Grouted Rock Bolts Based on Pull-Out Experiments Utilizing Fiber Optics Technology and Associated Numerical Modelling of Such Support Elements

2019 ◽  
Vol 38 (2) ◽  
pp. 1389-1407 ◽  
Author(s):  
Nicholas Vlachopoulos ◽  
Daniel Cruz ◽  
Bryan Stanley Anthony Tatone ◽  
Andrea Lisjak ◽  
Omid K. Mahabadi ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Fiber Optics ◽  
Rock Bolts ◽  
Pull Out ◽  
Axially Loaded ◽  
Grouted Rock Bolts

scholarly journals Laboratory pull-out tests on fully grouted rock bolts and cable bolts: Results and lessons learned

2017 ◽  
Vol 9 (5) ◽  
pp. 843-855 ◽  
Author(s):  
Isabelle Thenevin ◽  
Laura Blanco-Martín ◽  
Faouzi Hadj-Hassen ◽  
Jacques Schleifer ◽  
Zbigniew Lubosik ◽  
...  
Keyword(s):  
Lessons Learned ◽  
Rock Bolts ◽  
Pull Out ◽  
Cable Bolts ◽  
Grouted Rock Bolts

scholarly journals Study on Mechanical Characteristics of Fully Grouted Rock Bolts for Underground Caverns under Seismic Loads

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Guoqing Liu ◽  
Ming Xiao ◽  
Juntao Chen ◽  
Hao Zhou
Keyword(s):  
Mechanical Characteristics ◽  
Load Transfer ◽  
Seismic Load ◽  
Seismic Loads ◽  
Stress Distributions ◽  
Rock Bolts ◽  
Pull Out ◽  
Underground Caverns ◽  
Grouted Rock Bolts

This study establishes an analytical model for the interaction between the bolt and surrounding rock based on the bearing mechanism of fully grouted rock bolts. The corresponding controlled differential equation for load transfer is deduced. The stress distributions of the anchorage body are obtained by solving the equations. A dynamic algorithm for the bolt considering shear damage on the anchoring interface is proposed based on the dynamic finite element method. The rationality of the algorithm is verified by a pull-out test and excavation simulation of a rounded tunnel. Then, a case study on the mechanical characteristics of the bolts in underground caverns under seismic loads is conducted. The results indicate that the seismic load may lead to stress originating from the bolts and damage on the anchoring interface. The key positions of the antiseismic support can be determined using the numerical simulation. The calculated results can serve as a reference for the antiseismic optimal design of bolts in underground caverns.

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

2019 ◽  
Vol 9 (22) ◽  
pp. 4781 ◽  
Author(s):  
Haneol Kim ◽  
Hafeezur Rehman ◽  
Wahid Ali ◽  
Abdul Muntaqim Naji ◽  
Jung-joo Kim ◽  
...  
Keyword(s):  
Rock Mass ◽  
Field Experiments ◽  
Classification Systems ◽  
Rock Bolt ◽  
Rock Bolts ◽  
Tunnel Support ◽  
Support Materials ◽  
Pull Out ◽  
Controllable Factors ◽  
Grouted Rock Bolts

Empirical classification systems do not provide details of the factors that affect the performance of fully grouted rock bolts, as they are based on average values. Fully grouted rock-bolt patterns during tunnel-support design are a part of the composite support, and they are functions of rock-mass quality and tunnel span. Various fully grouted rock bolts are used in situ in different environments, along with other tunnel-support materials in static and dynamic environments during tunnel construction. The rock-bolt performances are evaluated through pull-out tests that follow ASTM standards. Several field pull-out tests were conducted on cement and resin grouted rock bolts. Under groundwater flow conditions, inflated steel tube rock bolts were tested and the results were compared with fully grouted rock bolts. Based on field experiments and previous studies, the factors that affect rock bolt performances are divided into five groups with respective sub-factors. Natural parameters cannot be controlled to ensure safety, economy, and stability in tunnels. The controllable factors, too, can be varied only within a practical range. In conclusion, the factors investigated here should be considered with the empirical support pattern of rock-mass classification systems for safe and economical design.

scholarly journals The energy absorption behavior of novel composite sandwich structures reinforced with trapezoidal latticed webs

2021 ◽  
Vol 60 (1) ◽  
pp. 503-518
Author(s):  
Juan Han ◽  
Lu Zhu ◽  
Hai Fang ◽  
Jian Wang ◽  
Peng Wu
Keyword(s):  
Bearing Capacity ◽  
Energy Absorption ◽  
Sandwich Structure ◽  
Ultimate Load ◽  
Sandwich Structures ◽  
Elastic Displacement ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Composite Sandwich ◽  
Composite Sandwich Structures

Abstract This article proposed an innovative composite sandwich structure reinforced with trapezoidal latticed webs with angles of 45°, 60° and 75°. Four specimens were conducted according to quasi-static compression methods to investigate the compressive behavior of the novel composite structures. The experimental results indicated that the specimen with 45° trapezoidal latticed webs showed the most excellent energy absorption ability, which was about 2.5 times of the structures with vertical latticed webs. Compared to the traditional composite sandwich structure, the elastic displacement and ultimate load-bearing capacity of the specimen with 45° trapezoidal latticed webs were increased by 624.1 and 439.8%, respectively. Numerical analysis of the composite sandwich structures was carried out by using a nonlinear explicit finite element (FE) software ANSYS/LS-DYNA. The influence of the thickness of face sheets, lattice webs and foam density on the elastic ultimate load-bearing capacity, the elastic displacement and initial stiffness was analyzed. This innovative composite bumper device for bridge pier protection against ship collision was simulated to verify its performance. The results showed that the peak impact force of the composite anti-collision device with 45° trapezoidal latticed webs would be reduced by 17.3%, and the time duration will be prolonged by about 31.1%.

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