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... holes for the rock anchors were pneumatically drilled with a 140-mm diameter button bit to a depth of 1.6 m. They were placed with a minimum spacing of 1.5 m and a minimum distance of 3 m to the bench crest, as illustrated in Fig. 5 and shown in Fig. ...
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Fully grouted rock bolting is commonly used in roadway reinforcement in mining and tunnelling reinforcement.
Accurate determination of rock strength is always a crucial problem to ensure the stability of rock engineering, which can be estimated from experimental data at a small scale through size effect models. Previous studies examined the scaling behaviors of rocks from a deterministic perspective, ignoring the strength variabilities around the mean val...
This work is devoted to the study of factors affecting the formation of cement stone and its contacts with casing pipes, the development of recommendations and technological methods to improve the quality of well cementing. The main task of cementing wells is hermetic separation of rocks with different saturation patterns. The solution to this prob...
Citations
... Tu et al. (2022) studied the influence of grout's Poisson effect on interfacial shear stress for compression anchor in rock mass. Grindheim et al. (2023) conducted a fullscale pullout tests of rock anchors focusing on bond failure at the anchor-grout and grout-rock interfaces. ...
This paper focuses on a pullout failure of anchor rods used to stabilize rock slope at the sides of a road cut in a mountainous terrain. The objectives of this work are to analyze a case study of a pullout type of failure of anchor rods at highly fractured rock slope sides of a road cut called Dhila descent in Saudi Arabia, and also to investigate the possible mechanisms that caused this peculiar type of failure of the rock anchors and the landslides along the descent. Anchor rods exit out of the hole for a distance of few meters. Results of this analysis showed that the mechanism of this rock anchor failure is of the pullout type, caused apparently by the release of the energy stored in anchor rods at the post-tension stage during the construction period. This release is caused by the reduction of the bond strength between the rod and the grout at the anchorage end inside the hole. The displacements of the rods were computed based on the conservation of energy and work-energy principles. The amount of the displacements computed for a range of possibilities are comparable with those observed in the field. The bolt failure process is explained in terms of the debonding between the bolt and the grout. Recommendations were made to improve the design of such anchors. It is recommended to use fully-grouted, inclined, static rock bolts with a more ductile grout, and locked with nuts from both sides of the bearing block.
... Consequently, at the end of the bearing section, the pressure diminishes, and the upper bearing Section 1# (refer to Figure 1) comes into play. This transition leads to a shift in the anchorage section from a state of compression to tension [42]. With a further increase in the anchor head load, the entire bearing section enters a pressurized state. ...
Rapid advancements in construction technologies have accelerated the development of complex and deep underground structures, raising concerns about the impact of groundwater on structures, particularly anti-floating measures. Traditional tensioned anchors, commonly used for preventing flotation, suffer from limitations like low pull-out bearing capacity, shallow critical anchoring depth, and localized stress concentration. To overcome these limitations, this paper introduces a tension–compression dispersed composite anchor, which combines casing, load-bearing plates, and tensioned anchors. Comparative tests were conducted between these composite anchors and traditional tensioned anchors to analyze their anchoring behavior. Our results show that tensioned anchors exhibit a stable axial force distribution as anchoring length increases. By identifying abrupt changes in the axial force curve, optimal anchoring lengths for load-dispersed anchors can be determined, thereby enhancing rock and soil strength utilization. The tension–compression-dispersed composite anchor outperforms tensioned anchors, with 1.44 times the ultimate bearing capacity for equivalent anchoring lengths and 1.1 times the capacity for an additional 1 m length. It also displays superior deformation adaptability and structural ductility under high-bearing loads compared to tensioned anchors with extended anchoring lengths. Effectively mobilizing the strength of the lower anchoring segment within the rock and soil results in a lower critical anchoring depth and a more uniform distribution of lateral friction resistance. In conclusion, the tension–compression-dispersed composite anchor offers significant advantages, making it a promising engineering solution for anti-floating anchor systems in complex underground environments.
