Application of Soil Nail Retaining Wall in Urban Bridge Abutment Stabilization

For a large number of bridges built in the early days, the abutment area was filled with tapered slopes to ensure the stability of the abutment. The area covers a large area. Today's cities are expensive. This reinforcement method is obviously not suitable. Soil nail retaining wall is a new type of retaining technology that relies on the bonding force, frictional resistance, and surrounding soil on the contact surface between soil nails and soil to form a composite soil, thereby improving the stability of soil slopes. The bridge abutment is reinforced on the basis of the structure, which effectively solves the problem of large floor space.

At present, the reinforced retaining structures used in road and bridge engineering mainly include reinforced retaining walls, anchor retaining walls, and soil nail retaining walls.

Reinforced Earth Retaining Wall

Reinforced earth retaining wall is to arrange tie bars in the soil, and use the friction between the tie bars and the soil to improve the engineering performance of the soil, so as to achieve the purpose of stabilizing the soil. Reinforced earth retaining walls are all used in filling works, and the construction sequence is layer-by-layer reinforcement from bottom to top, backfilling, and compaction.

The mechanical mechanism of the anchor retaining wall is similar to that of the soil nailing retaining wall, and both rely on the bonding force and frictional resistance on the contact surface between the soil nail or the anchor and the soil to improve the stability of the soil slope, and both can be applied in excavation works.

Anchor Retaining Wall

Compared with the soil-nailed retaining wall, the anchor bolts are arranged at a larger spacing, and the single bolt bears a larger load. To prevent the wall from being damaged by punching, its end structure is more complicated, and it is generally anchored on the transverse and longitudinal beams.

Soil-Nail Retaining Wall

The soil nails in the soil nail type retaining wall are arranged at a small spacing, and the load borne by a single soil nail is small. Even if individual soil nails fail, the impact on the entire structure is not large. Slabs and shotcrete panels can meet the force requirements. In actual construction, because the bolt is generally long, large-scale machinery and corresponding work surfaces are required, the length of the soil nail is short, the diameter is small, the construction equipment is light, and the operation is flexible.

The soil nails in the soil nailing retaining wall are divided into many kinds of materials, including ordinary steel bars, ordinary anchor rods, and self-drilling soil nails. Due to their own limitations, ordinary steel bars and ordinary bolts cannot be constructed in loose and broken geological conditions. The self-drilling soil nail integrates the three functions of drilling, grouting, and anchoring, which can effectively solve the problems of difficult-to-form holes and easy-to-collapse holes.

Advantages of Soil Nailing Retaining Walls

Compared with other retaining structures, soil-nail retaining walls have the following advantages:

1. The ability of the soil itself is rationally utilized so that the retaining structure and the soil are integrated to achieve the purpose of strengthening the soil.

2. The protective panel is thinner, the structure is more flexible, and has better earthquake resistance.

3. The construction equipment is light, the operation method is simple, and the construction period is short.

4. During construction, excavation and construction are carried out layer by layer, which has little disturbance to the retained soil and maintains a good state of original soil balance.

5. The construction work area is small, the material consumption and engineering volume are small, and the cost is low.

Construction Technology of Soil Nail Retaining Wall

In the construction of soil nail retaining walls, the method of excavation and construction is adopted. In order to ensure that the soil body does not collapse during the construction process, it is required that the construction must be layered during the excavation process. A layer of soil nails and protective panels shall be constructed, and then the construction of the next layer of soil nails shall be carried out until the construction reaches the foundation position of the protective panels. Before the completion of the construction of the upper layer of soil nails, the next layer of soil shall not be excavated, and over-excavation is strictly prohibited.

Soil-nailed retaining walls are widely used in cutting slope reinforcement and foundation pit engineering. The introduction of soil nail retaining walls technology into bridge abutment reinforcement projects provides a new idea for the design of bridge abutment reinforcement projects.