How to Use Self Drilling Rock Bolts in Tunnel and Mining Constructions?

In the construction of excavation, such as tunnels, mining, and other underground projects, we have to support the soil and rock mass to ensure the people and equipment are safe. Generally, we use rock bolts to do this. Rock bolt has a long history of being used in tunnels and mines and now it is the turn of self-drilling rock bolts. Today, Sinorock will introduce you to how to use self-drilling rock bolts in tunnels and mining constructions.

constructions of excavating

Factors Affecting Rock Mass Stability

In the intricate world of tunneling and mining constructions, the stability of rock masses is paramount to ensure safety and longevity. Several factors significantly influence rock mass stability:

1. Lithology

The influence of lithology on rock mass stability includes two aspects. One is the influence of the physical and chemical properties of the rock on the stability of the rock mass, including the hardness of the rock and soil, weathering resistance, softening resistance, strength, composition, and water permeability. The influence of rock mass stability is reflected in the degree of development of joints and fissures and their distribution, the cementation of structural planes, the distribution of weak planes and fracture zones, etc.

2. Structure

Rock mass structure includes two aspects, structural plane and structural body. Structural planes refer to the differentiation planes and discontinuous planes of rock materials, planes, fractures, layers, bands and various geological interfaces with certain directions, scales, shapes and characteristics. The structure is composed of various structural surfaces of different occurrences, and the rock mass is cut into unit blocks. The rock mass structural factors that affect the stability of rock mass mainly include the inclination, dip angle and strike of the structural plane, the number and continuity of the structural plane and so on.

3. Surface Water

The impact of surface water on the rock mass is small because the rock mass has high strength and is not easily eroded. However, if the rock is severely weathered and the rainfall intensity is high, the influence of surface water on the stability of the rock mass cannot be underestimated.

Types of Rock Bolts in Tunnel and Mining

Understanding the diverse range of rock bolts is crucial for tailoring support systems to specific geological conditions. In the realm of tunneling, several types of rock bolts find applications:

1. Friction Bolts

Utilizing thin-walled steel pipes with longitudinal slits, friction bolts generate resistance against the radial pressure of the hole wall, providing stability and support in tunnels.

2. Expandable Rock Bolts

These bolts, crafted from specially shaped cavity rods processed with thin-walled steel pipes, expand through high-pressure water injection. This expansion generates frictional resistance on the hole wall, anchoring the rock mass effectively.

3. Pre-stressed Rock Anchors

This type of rock anchor can provide a pre-stress to prevent rock mass deformation. Through the anchoring force generated by the anchor head, certain pre-compression stress of the rock anchor is applied to the surrounding rock to actively strengthen the rock mass.

4. Self-Drilling Rock Bolts

The most widely used anchoring tools in geological constructions, self-drilling rock bolts integrate drilling, grouting, and anchoring in a single process. Suitable for broken rock and challenging drilling conditions, these bolts enhance construction efficiency by eliminating the need for casing pipes.

Self Drilling Rock Bolts

Benefits of Using Self-Drilling Rock Bolts in Tunnel and Mining Constructions

Self-drilling rock bolts offer a myriad of advantages, making them indispensable in tunneling and mining projects:

1. All-in-One Solution

The integration of drilling, grouting, and anchoring streamlines the construction process, enhancing efficiency and reducing operational complexities.

2. Versatile Drill Bits and Thread Hollow Bars

With a variety of drill bit options like EX, EY, ES-F, EXX, EYY, ESS-F, and clay bits, and two types of thread hollow bars (R thread and T thread), self-drilling rock bolts offer adaptability to diverse geological conditions and drilling rigs.

3. Accessibility in Narrow Spaces

The ability to cut or lengthen thread hollow bars at any position using couplers provides unparalleled convenience in supporting rock masses within confined spaces where large equipment cannot reach.

Step-by-Step Guide on How to Install Self-Drilling Rock Bolts

1. Preparation

Prior to drilling, ensure the drilling rig, rock bolts, and grout are ready. Connect the drill bit to the hollow bar, check for any blockages in the inner path, and connect the grouting pipe to the hollow bar.

2. Drilling and Grouting

Simultaneously start the drilling rig and grout machine. Drill and grout in unison, ensuring that the grout effectively strengthens the surrounding soil or rock mass.

3. Solidification and Installation

Allow the grout to solidify and then proceed to install the plate and nut, completing the self-drilling rock bolt installation process.

Application Structure of Self-Drilling Rock Bolt in Tunnels and Mining

In the realm of tunnels and mining, self-drilling rock bolts find extensive applications in various support structures:

sinorock self drilling rock bolts in tunnel and mining

1. Fore-piling

Used for initial support during tunneling, self-drilling rock bolts employ high-pressure grouting to strengthen soil or rock mass, ensuring stability during excavation.

2. Radial Support

These rock bolts provide essential support, reinforcing the radial aspects of the tunnel to withstand external pressures and maintain structural integrity.

3. Tunnel-Face Support

Self-drilling rock bolts play a pivotal role in supporting the tunnel face, ensuring safety and stability during the excavation process.

4. Locking the Foot Support

Employed to secure the foundation and prevent subsidence, self-drilling rock bolts contribute to the overall stability of the tunnel or mining structure.

5. Reinforcement of the Tunnel Portal

Ensuring the stability of the entrance or exit of the tunnel is crucial, and self-drilling rock bolts are instrumental in reinforcing the tunnel portal.


Mastering the art of using self-drilling rock bolts in tunnel and mining constructions is key to achieving optimal stability and safety. With a deep understanding of rock mass stability factors, types of rock bolts, and installation guides, engineers and professionals can navigate the challenges of geological construction with confidence. The versatile and efficient nature of self-drilling rock bolts continues to make them a cornerstone in the toolkit of tunneling and mining projects, unlocking the potential for safer and more robust underground structures. For further inquiries or product needs, contact us at, and our team will respond promptly to assist you.

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