What Is Soil Nailing?Stabilization of Slope in Loose Soil Using Soil Nails

In recent years, with the acceleration of the urbanization process, construction excavation in loose soil is inevitable. At present, there are many support methods in the process of excavation and support, such as soil nail walls, ground anchors, concrete gravity walls, etc., and soil nails are effective methods for stable vertical excavations in urban areas. The main advantage of the soil nail wall is that the work space is large, the construction machinery and equipment are lightweight, the construction speed is fast, and the adaptability is strong. It can adapt to full settlement and uneven settlement. This article will introduce the type of soil nails and project case used in loose soil.

What Is Soil Nailing?

Soil nailing refers to the geotechnical reinforcement support technology. It is composed of soil nails group, reinforced in-site soil, sprayed concrete surface, reinforced mesh, and necessary waterproof systems. It is an engineering method that uses the "top -down" to stabilize existing slope or excavation. This passive reinforcement system repair unstable natural slope, or build a new or existing ultra-steep slope with closely spaced steel inclusions.

The soil nails are the rods installed in the soil. It can be installed in various methods, including directly driven, drilling, drilling and grouting, simulations drilling and grouting, and can be installed in various soil conditions that adapt to the changes in ground conditions.

soil nail wall

Common Types of Soil Nails

During construction, you can choose appropriate soil nail installation method and type of soil nails according to geotechnical conditions.

Self drilling soil nails

Self drilling soil nails are composed of hollow anchor bar, coupler, nuts, plate, centralizer and drill bits. The soil nails are hollow in the center and the grout travels down the bars and out from holes in drill bit.. The nail technology combines the three-step method of installing the soil nails into one (drilling, grouting and anchoring). Its main advantage is not only to keep drilling smoothly during drilling, but also the rotation effect of the drill bit can mix the grout with the soil around the drilling, which produces a rough, irregular, valid grouting body that the diameter is greater than the diameter of drill bit. Thus it can greatly support the soil.

Self drilling anchor bolt are particularly suitable for collapsed soil or landslide mountains, with high installation efficiency and tensile resistance.

Driven soil nail

Driven soil nail is to drive a certain length and densely steel bars, steel pipes in the soil (there is also a 'wool bamboo nail' in the mud areas). It combine with the soil to form a complex.

Driven soil nails are tied densely, and due to their small diameter, low friction strength, low bearing capacity, and limited length, entering soil nails can be scaled through manpower or vibration drilling, hydraulic hammer and other mechanicals.

The advantage of driven soil nails is that no pre -drilling holes are required, small disturbance of the soil in situ, and the construction cycle is short.

Advantages of Self Drilling Soil Nails

The drilling, grouting and anchoring function can be integrated, especially suitable for loose strata that are easy to collapse and difficulty to drill.

Diverse installation methods, such as impact drilling, rotation drilling, and rotation and impact drilling.

It can mix the grout with the soil around the drilling, which produces a rough, irregular, valid grouting body that the diameter is greater than the diameter of drill bit. Thus it can greatly support the soil.

Full thread along the anchor bar body. It can be connected with a coupler and arbitrarily cut at the scene to facilitate the construction of limited space.

Compared with the traditional driven soil nails and drilling and grouting piles, its construction efficiency is higher and more economy.

Slope Stabilization of in Loose Soil Using Soil Nails

Self drilling anchor bolts can achieve synchronous drilling and grouting, so when used as soil nails, it can be used for the slope support, foundation support, and retaining walls in complex strata. The following is a project case of stabilization of slope in loose soil using self drilling soil nails.

The project is a latter slope engineering treatment of civilian houses, the slope is 80 °, the height is 18m, and the support width is 20m. There is a 11-storey resident building on the south side of the slope. The slope did not do any support treatment at the beginning, and the slope geology was a backfill floor with poor stability, so the R32 self drilling anchor bar with higher construction efficiency was used for support.

design drawing

The above is the relevant introduction of soil nails. The self drilling anchor system is used as a soil nail without casing, which can greatly improve the construction efficiency, shorten construction period, and reduce the overall cost. At present, self drilling anchor system are widely used in broken rock formations that are difficult to drill, such as pebbles and loose fill. In addition to being used as soil nails, they can also be used as rock bolts, ground anchors, and micropiles.

Sinorock is a professional manufacturer of self drilling anchor bolts. As a leading expert in the ground support industry, Sinorock team has many years of experience in providing complete geotechnical engineering services. If you have any needs or questions about self drilling anchor bolts and their applications, please feel free to contact us at sinorock@sinorockco.com.

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