The " Cutting - Edge Tech " of Rock Strata Support : An In - Depth Guide to Slotted Rock Bolts

Guardians of Underground Safety

In underground mining, tunnel excavation, and slope stabilization projects, the stability of rock strata serves as the lifeline of construction operations. Faced with complex surrounding rock environments, a support material known as the Split Set Bolt (or Friction Bolt) has emerged as the global choice of preference, thanks to its "ready-to-install" nature. But what exactly is it? And how does it work?

I. What is a Slotted Tube Rock Bolt?

A slotted tube rock bolt — academically often referred to as a friction - type rock bolt — is a mechanical support device that provides full-length anchorage.

Physical Structure : It consists of a high-strength steel tube featuring a longitudinal slot that runs along its entire length. One end of the bolt body is tapered (to facilitate insertion into the borehole), while the other end is fitted with a welded bearing ring designed to secure a dome plate.

Working Principle : The diameter of a slotted tube rock bolt is typically 2 to 5 mm larger than the diameter of the borehole. When the bolt is forcibly driven into the hole using impact force, the longitudinal slot is compressed and closes. The resulting radial pressure generates immense frictional force along the entire length of the bolt body, thereby firmly locking the surrounding rock strata in place.

II. Key Concepts Regarding Slotted Tube Rockbolts

1. Immediate Support

This constitutes the greatest technical advantage of slotted tube rockbolts. Unlike resin-grouted or cement-grouted rockbolts—which require curing times of several hours or even longer—slotted tube rockbolts achieve their full load-bearing capacity the very instant installation is complete. This plays a crucial role in preventing the collapse of surrounding rock during the initial stages.

2. Unique "Yielding" Property

Underground rock masses are dynamic environments subject to constant change.
Slotted tube rockbolts possess a certain degree of flexibility; when the surrounding rock undergoes slight displacement, the rockbolt can execute minute slips in synchronization with the rock strata without easily fracturing. Even more remarkably, the compressive forces exerted by the rock cause the slotted seam to close more tightly, thereby increasing frictional resistance and achieving the effect of becoming "more stable the greater the pressure."

3. Streamlined Installation Process

No Auxiliary Materials Required : Eliminates the need for resin cartridges or grouting.

Simple Operation : Installation can be completed using only a standard pneumatic drill or a rock drilling jumbo.

Cost Reduction : Minimizes material transport costs and on-site labor time.

4. Specifications and Material Selection

Common Specifications: Standard diameters include 33mm, 39mm, 46mm, and 47mm, with lengths typically ranging from 0.9m to 3.0m.

Corrosion Protection: For damp or acidic underground environments, hot-dip galvanizing is typically applied to extend the service life of the product.

III. Application Scenarios: Where Is It Needed Most?

Due to their high efficiency, split-set rock bolts are widely utilized in the following fields:

Metal Mines : Support for underground roadways in gold, copper, iron, and other mines.

Road/Railway Tunnels : Initial support and reinforcement for sections with weak surrounding rock.

Hydropower Projects : Excavation of underground powerhouses and slope protection.

Temporary Support : Construction fronts requiring rapid advancement and characterized by variable geological conditions.

Conclusion : Choose Quality Support to Ensure Construction Safety

As a "mainstay" of underground engineering support, the quality of split-set rock bolts directly bears upon the safety of human life.

Application Scenarios: Where is the Need Most Urgent?

Leveraging their high-efficiency characteristics, friction-type rock bolts (Split-set rock bolts) are widely utilized in the following fields:

Metal Mines : Used for supporting underground roadways in various mining operations, including gold, copper, and iron mines.

Road/Railway Tunnels : Employed for the initial support and reinforcement of tunnel sections characterized by weak surrounding rock.

Hydropower Projects : Applied for excavation support in underground powerhouses and for slope stabilization.

Temporary Support : Ideal for construction projects requiring rapid excavation and involving variable geological conditions.

Choose high-quality support solutions to ensure construction safety.