How Does Self Drilling Rock Bolt Stable Broken Slopes and Rock

Slopes are a very common part of many construction projects, such as highways, railways, dams, civil constructions. In most conditions, we need to stable these slopes in case that they have a shift which would results in an inestimable loss that we can’t bear. Especially, we must stable the slopes when the geotechnical conditions are broken and loose.

Slope Support of Expressway in Santiago - R32 self-drilling rock bolt

There are kinds of slope stabilization methods that could be selected for different conditions and the advantages and the shortcomings are apparent. Today, Sinorock will introduce you a new method, self-drilling rock bolt, that has been widely used to stable broken rocks and slopes.


What is self-drilling rock bolt?

How does self-drilling rock bolt stable broken slopes and rocks?

What’s the advantages using self-drilling rock bolt to stable broken slopes?

Real cases for reviewing.


What is self-drilling rock bolt?


Self-drilling rock bolt, also called self-drilling anchor system, is a tool to anchoring rocks and soils. It consists of a drill bit of kinds of types that adapted to different conditions, a hollow steel bar of various outer and inner diameters, a coupler, a plate, a nut, and a centralizer. R or T thread is available on the surface of the hollow steel bar.

self drilling rock bolt system

Length and diameter

The self-drilling rock bolt is produced in sections, and the standard length is 2m, 3m, 4m, and 6m. if a single hollow steel bar can’t meet the maximum drilling depth, we can extend it by several couplers. The outer diameter of self-drilling rock bolt ranges from 25mm to 200mm, which leads to a large scope of ultimate load and yield load.

rock bolt hollow steel bar


During application, the biggest influence on the service life of rock bolt is the corrosion of surrounding environment, so the self-drilling rock bolt is corrosion protected by hot-dip galvanizing or epoxy, or we can change the material of hollow bar to stainless steel.

How does self-drilling rock bolt stable broken slopes and rocks?

First, the self-drilling rock bolt will drill into the rock and soil of the slope to be reinforced to a required depth. Simultaneously, the grouting will be grouted in the drilling hole from inner to outside. Under the high pressure, the grouting could be pressed into the crack of rock or soil. The broken rock or loose soil will be cemented together. With the drill bit (sacrificial) at the top end of the hollow bar and plate and nut on the other end, self-drilling rock bolt can provide the force after drilling in to stable the slope.


Usually, we will grout twice. the water-cement ratio of first time is about 1:1, and the second will be 0.45~0.6:1. The grouting pressure is about 0.3~0.5Mpa.


What’s the advantages using self-drilling rock bolt to stable broken slopes?

Self-drilling rock bolt, which combines drilling, grouting and anchoring together, is suitable for broken rock and conditions which are difficult to drill holes. Casing pipe is omitted in construction, which greatly improves the construction efficiency.

It has a rich variety of drill bits, and drill bit can be selected according to the properties of rock and soil, which can improve the drilling efficiency.

It can fill cracks, consolidate rock mass and soil layer through pressure grouting, and has good grouting spreading radius and reliable anchoring quality.

The hollow anchor bar can be cut arbitrarily and lengthened by the coupler. Therefore, it is suitable for the construction in the narrow space which the large equipment cannot enter.

Real cases

slope support of self drilling bolt

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