Rock bolts play a pivotal role in diverse engineering projects, serving as essential elements for securing, supporting, and safeguarding structures. With the continuous advancement of technology, expandable rock bolts, as a new rock bolt technology, have gradually received widespread attention and application. So, what are the advantages of expandable rock bolts compared with other rock bolts?
Difference of the following three bolts
Due to the wide variety of rock bolts, we only selected two types for comparison with expandable rock bolts. The details are as follows.
| Anchor type | Advantages | Suitable conditions | Product features |
| Expandable rock bolt | 1. Temporary support or initial support for tunnels and underground works. 2. It can offer full length support. 3. It can offer active support. | 1. Suitable for medium and hard rock. 2. Suitable for high stress rock layer that is prone to rockburst, mainly for tunneling works. | 1. Moderate bearing capacity for single bolt. 2. Suitable for tunnels, mining and other projects with small spans. 3. Light weight, easy installation. |
| Expansion shell anchor bolt | It can offer immediate support. | 1. Suitable for medium and hard rock. 2. Suitable for high stress rock layer that is prone to rockburst, mainly for underground. | 1. High bearing capacity for single bolt. 2. It is connectable. |
| Self drilling anchor bolt | 1. Used for temporary and permanent support. 2. Combine drilling, grouting and supporting together. 3. High anchorage force by pressure grouting. | 1. It is suitable for all kinds of surrounding rock such as soft, medium hard and hard rock, especially in the weak surrounding rock, fault fracture zone, sand pebble, etc. 2. Suitable for slope, foundation, tunneling and underground engineering. | 1. High bearing capacity for single bolt. 2. Full length thread and can be cut and coupled at any position. 3. Full range of SDA, high anchorage force. |
For a more in-depth comprehension of the practical benefits of expandable rock bolts in projects, the following case study can provide valuable insights.
Application in plastic clay
During the construction of a water supply project in southern Italy, a tunnel passing through homogeneous limestone suddenly encountered a plastic clay zone. Upon observing the deformation of the side wall, it became evident that tunnel excavation and blasting could not proceed as planned. To resume construction, two issues must be addressed and resolved. The first challenge involves anchoring the steel arches that reinforce the side walls using rock bolts. These rock bolts must possess the capability to withstand substantial loads in soft rock and soil. The second challenge pertains to stabilizing the exposed tunnel face. Following pullout tests on various anchor types, the construction team successfully and efficiently completed the tunnel construction in the plastic clay zone by opting for expandable rock bolts. This approach proved to be a quick and cost-effective solution.
Application in high slopes
In the construction of a specific expressway, there is a requirement to build a steep slope on one side of the mountain. Considering that the stability of high slopes is crucial to the safety of the entire highway, the designers decided to use expandable rock bolts for slope reinforcement. After construction, the slope stability has been significantly improved, ensuring the safe operation of the highway.
Advantages of expandable rock bolts
The advantages of expandable rock bolts are evident in the following aspects:
Simple construction
The installation process of expandable rock bolts is notably straightforward, requiring no additional tensioning or fixing. After the drilling is completed, the expandable rock bolt is inserted into the drilled hole, and its expansion is achieved by injecting water, completing the anchoring process. This construction method not only improves construction efficiency but also reduces the construction difficulty and cost.
No grouting required
It is not affected by groundwater and is suitable for strata with more water.
Achieve rapid full-length anchoring
With seismic resistance, unaffected by tunnel face excavation or blasting during construction.
Good extensibility
An elongation of up to 20% makes it suitable for use in rockburst-prone formations.
Cost-effective
Although the manufacturing cost of expandable rock bolts is relatively high, they have good durability and stability and can maintain the anchoring effect for a long time. In long-term engineering projects, the overall cost-effectiveness of expandable rock bolts is better than that of traditional anchors.
In summary, expandable rock bolts have significant advantages in ease of installation, load-bearing capacity, and anti-corrosion performance. It can effectively shorten the construction period, reduce costs, and improve project quality. With the continuous advancement of technology and the expansion of application scope, we believe that expandable rock bolts will be applied and developed in more fields.
