Installation of resin-grouted rockbolts in hard rock mining: challenges and solutions for improved safety

Maepa, T.G.; Zvarivadza, T.

doi:10.17159/2411-9717/2017/v117n4a3

Cited by 6 publications

(3 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This makes it possible to preload. Due to different gelation times, roof bolting should be installed by experienced operators to prevent the premature shearing of the resin at the point of contact between the rock mass and resin or resin-rod during the rotational movement of the rock bolt [6]. Selecting the technology for installing roof bolting on quick-setting or slow-setting cartridges should be based on striking a balance between the install of potential excavations designated for bolting and the time needed to secure them.…”

Section: Introductionmentioning

confidence: 99%

Flexibility and Load-Bearing Capacity of Roof Bolting as Functions of Mounting Depth and Hole Diameter

et al. 2019

View full text Add to dashboard Cite

This paper presents the results of laboratory tensile testing of segmentally-installed glue-in roof bolting. We studied roof bolting of the type Olkusz-16A (Boltech Sp. z o.o., ZGH Bolesław S.A., Bukowno, Poland), additionally equipped with a steel rod coil, which was mounted in steel cylinders filled with a concrete mixture using multi-part resin cartridges with a diameter of 0.024 m and length of 0.045 m. The mounting depths were 0.1 m and 0.2 m, respectively. Our main purpose was to determine the effect of the bolt hole diameter, which assumed the values 0.028 m, 0.032 m, 0.035 m, and 0.037 m, respectively, on the load-bearing capacity of the roof bolting in relation to the mounting depth. We found that the mounting depth of 0.2 m was sufficient for the roof bolting to exhibit its full load and displacement properties for all four diameters of the bolt hole. To determine whether the roof bolting was capable of transferring the load in situ, we presented the results of the predicted load on the roof bolting applied in a room and pillar mining method in an underground mine of zinc and lead ore deposits. Our objective was to determine the influence of the room and pillar mining method geometry on the range of the fault zone of rocks around pits. We designed the deposit excavation model using the Examine3D numerical modeling software, which is based on the boundary element method. We created three-dimensional models for three variants of working space opening widths: featuring two, three, and four rows of rooms. The geometry of rooms and pillars corresponded to the mine conditions; the width, height, and length parameters were all 5 m. We determined the strength, strain, and structural parameters of the rock mass on the basis of laboratory studies of the drill core and rock forms collected from the room longwall. We used the strength factor to specify the maximum range of the fault zone of rocks around pits. In the last stage of research, we compared the load value obtained based on numerical testing with the maximum load obtained in the tensile strength tests of the roof bolting and determined the safety factor of the segmentally-installed roof bolting.

show abstract

Section: Introductionmentioning

confidence: 99%

Flexibility and Load-Bearing Capacity of Roof Bolting as Functions of Mounting Depth and Hole Diameter

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Conventional bolted stope support uses 30 second or 60 second set-time resin capsules Maepa and Zvarivadza (2017), and these formed the benchmark for performance of the pumped grout system. At the time of development (2012 -2104) no cement grouts were available that met these requirements.…”

Section: Grouting Of the Self-drilling Rock Boltsmentioning

confidence: 99%

Development of a remote control rock bolting system for narrow seam hard rock mines

O'Connor¹,

Sertic²

2019

Proceedings of the Ninth International Conference on Deep and High Stress Mining

View full text Add to dashboard Cite

An estimated 90 percent of South Africa's gold-bearing reefs are less than 1 m thick (Joughin 1976). A large mineral resource therefore lies in seams that are becoming increasingly uneconomic to extract because of the grade dilution caused by raising the mining height to suit currently available mechanized mining equipment (Harper 2008). A similar situation applies to platinum resources. Historically in SA, mining of these narrow seams has been carried out by labour intensive methods, with little equipment beyond hand-operated rock drills. However, the arduous and hazardous work environment is becoming increasingly unattractive to both the workforce and mine operators. Globally, major mining companies are striving to increase safety by removing workers from the immediate vicinity of the operations and increasing productivity by better integration of the phases of the regular mining cycle to reduce cycle times (Lynch and White 2013). Attaining both objectives requires going beyond mechanization to high degrees of automation and/or remote control of equipment. These factors present a challenge to South African mine operators and their equipment suppliers as mechanization of the narrow seam, hard rock mining environment has proven difficult with scant success (Pickering and Ebner 2006, and Harper 2008). This paper describes the development of a semi-automated, remote controlled rock bolting system for hard rock mines with a mining height of between 0.9 m and 1.2 m (ULP Project). The rock bolting system required development of fully mechanized, remote controlled rock bolting rig, novel rock bolts and a pumpable, fast-acting resin grout to secure the bolts. The introduction of systematic rock bolting has resulted in a decrease in rock-related accidents, but the many manual operations required in drill-steel and bolt handling in confined spaces and close proximity to high-powered equipment, has led to increased injuries (particularly hand injuries) to the rock bolting operators (Makusha 2015). Remotecontrol equipment has the potential to mitigate such injuries. The rock bolter is one component of an equipment suite enabling full mechanization of rock breaking by blasting, clearing broken rock and rock support. Development started in 2012 and the bolting rig has been operating on a platinum mine since 2017. Deployment of further equipment suites is planned for 2019.

show abstract

“…The main function of the grout, which fully fills the annulus between the rock bolt and the borehole wall, is to provide a mechanism for load transfer between the rock mass and the reinforcing element [10][11][12][13][14][15]. At present, it is commonly accepted that higher bond strengths can be realized with 4-6 mm resin annulus [16][17][18][19], and important factors influencing the quality of encapsulation in rock bolting were reported as borehole diameter, resin annulus thickness, installation time, gloving, and hole over drill [16]. It should be noted that the effectiveness of the installed roof bolts can be compromised by gloving.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on anchorage performance of rockbolts by adding steel aggregates into resin anchoring agents

et al. 2021

View full text Add to dashboard Cite

Pull-out testing was carried out to evaluate the effects of shape, size and concentration of steel aggregates on anchorage performance. Steel grit with particle sizes of 1.5, 2.0, and 2.8 mm and steel shot diameters of 1.4, 2.0, and 2.5 mm were used as steel aggregates and were added into the resin anchoring agent. For each kind of steel aggregate, either 30, 40 or 50 aggregates were used to evaluate the effects of different steel aggregate densities. Anchorage specimens were prepared using ϕ20mm rebar bolts and steel sleeves. Compressive and shear strengths of resin containing steel aggregates, the pullout curve, and the circumferential strain of the sleeves were measured, and the energy consumption was calculated. Results show that compressive and shear strengths of resin containing steel grit and steel shot are increased by 8.4%-17.0% compared to pure resin. For the aggregate numbers of 30, 40 and 50, the anchoring force is increased by 7.9%, 7.5% and 6.5%; energy consumption is increased by 19.2%, 15.0% and 18.6%; and the circumferential strain of the specimen is increased by 28.4%, 25.1% and 39.5%, respectively. The effect of aggregate size on anchoring performance is significant; that is, the aggregate sizes of 1.4~1.5, 2.0 and 2.5~2.8 mm increase the anchoring force, energy consumption and sleeve circumferential strain by 8.5%, 4.6% and 8.7%, 16.0%, 8.4% and 28.4%, and 17.9%, 23.3% and 51.9%, respectively. The relationships of the anchoring force, energy consumption, and circumferential strain with steel aggregate quantity and size are formulated. Results show that the addition of steel aggregates increases the compressive and shear strengths of the resin, and steel aggregate quantity and size have significant impact on anchoring performance. This paper provides the basis for optimization of resin anchoring agents used in the mining industry. The impact of anchoring agent shear strength and residual shear strength on the anchoring effect were also discussed based on the failure analysis of the anchoring section.

show abstract

Installation of resin-grouted rockbolts in hard rock mining: challenges and solutions for improved safety

Cited by 6 publications

References 3 publications

Flexibility and Load-Bearing Capacity of Roof Bolting as Functions of Mounting Depth and Hole Diameter

Flexibility and Load-Bearing Capacity of Roof Bolting as Functions of Mounting Depth and Hole Diameter

Development of a remote control rock bolting system for narrow seam hard rock mines

Experimental study on anchorage performance of rockbolts by adding steel aggregates into resin anchoring agents

Contact Info

Product

Resources

About