Rock Bolt V.S. Soil Nail: What Are The Differences?

 There are many professional terms in construction that are relatively similar, but the actual usage is very different. Only by understanding clearly can the construction be carried out more safely and efficiently. This article will analyze and compare soil nails and rock bolts.


What Are Soil Nails

Soil nailing is a slope-supporting method by an in-situ soil reinforcement technique. This technique involves the insertion of rebars into the soil body, then the reinforcing mesh is laid on the slope surface. And finally, concrete is sprayed with the combination of the earthwork slope.


What Are Rock Bolts

Rock bolts are steel threaded rods that are inserted into rock mass to stabilize underground rock and soil structures during excavation. In simple terms, a rock bolt is embedded in the rock and can bear the tension of the rod.

Rock bolts are used as the main support for structures such as tunnels and mines where safety is critical.

There are many types of rock bolts such as self-drilling rock bolt and Swellex-bolt, and the design of rock bolts depends on the rock quality and type of excavation.


Different Mechanism Between Soil Nail And Rock Anchors

Although soil nails and rock anchors also play the role of support, their force principle is different, mainly in the following aspects.

Soil nailing technique, on the other hand, is to place soil nail bodies of a certain length and distribution density within the soil body to act together, thus compensating for the lack of the soil body's own strength. It not only effectively improves the overall stiffness of the soil body and makes up for the weakness of low tensile and shear strength of the soil body. Through the interaction, the soil body's own structural strength potential is given full play, changing the nature of slope deformation and damage, significantly improving the overall stability. And more importantly, the soil nail wall is subjected to load process will not occur in the process of sudden collapse slip like the plain soil slope.


In contrast, rock bolts often combined with cement slurry bonded to the soil to form the anchorage effect, which is mainly applied in hard rock. Rock bolts are actively stressed, i.e. by applying prestress to the anchor bars, the excessive deformation of the soil is restricted before the excavation.

Rock bolt is an anchoring technique that transfers the tensile stress of a structure to a deep stable stratum or reinforces an unstable rock mass, forming a load-bearing structural system in which the rock bolt and the rock mass interact and act together. Rock bolts limit the rock loosening and shear displacement. In addition, it increases the friction force between rock layers.


Different Applications Between Soil Nail And Rock Anchors

Soft Ground: Soil Nail

Slope stabilization and support

Permanent retaining wall construction

Temporary excavation support

Landslide prevention


Hard Rock: Rock Bolt

Used to secure unconsolidated rocks in underground excavation projects, such as the mining and tunneling industry

Permanent reinforcement of underground excavations

Permanent roadways and excavations

Provide strata support in a wide variety of rock conditions (weak and competent),

Reinforcing concrete dams, bridge abutments, rock cliffs, and road cuts.

Prevent rock fall during excavation


Self-Drilling Rock Bolt:

As a new anchorage technique, self-drilling anchor bolts can be used as soil nails and rock anchor bolts in slope reinforcement, underground construction, tunneling engineering, etc. For the advantages of low-cost, fast construction, without casing of self-drilling anchor bolt, it now has shown wide application prospect.

In some rocky slopes or tunnels with weathered surfaces and prone to collapse stratum, self-drilling rock bolts can be drilled and then grouted to bond the rock blocks together and enhance rock mass stability. Such as the reinforcement of rocky slopes of collapse-prone highways and railroads, and in loose tunnel openings instead of conventional pipe sheds.



Although both soil nails and rock bolts have the function of reinforcing and supporting the soil and rock mass, but due to their mechanism and application scenarios are different, the geological conditions of the construction site should be fully analyzed when selecting construction support materials in order to make the construction safer and more efficient.

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