I. Project Background
The riverbanks of an urban inland river were severely damaged and collapsed due to long-term water flow scouring and the impact of surrounding construction activities. This not only threatened the lives and property safety of nearby residents but also caused damage to the ecological environment of the river. Therefore, the gabion retaining wall technology was adopted for river regulation.
II. Design Scheme
Wall Material: Based on the environment of the river channel, the galvanized steel wire mesh gabion wall surface was selected, which has good anti-rust performance and a relatively low cost.
Structural Design
The retaining wall was designed in a trapezoidal shape, with a bottom width of 3 meters, a top width of 1 meter, and a height of 4 meters.
The size of the gabion cage was 2m × 1m × 1m, and the mesh size was 60mm × 60mm.
The foundation adopted a 0.5-meter-thick concrete cushion layer, which was buried 1.5 meters deep into the riverbed.
Drainage Design: PVC drainage pipes with a diameter of 50mm were installed every 2 meters on the wall body, and gravel was filled inside as a filter layer.
III. Construction Process
Site Preparation: The collapsed areas along the riverbank were cleared first, removing loose soil, weeds, garbage and other obstacles. The total station was used for precise surveying and setting out to determine the position of the retaining wall and the boundary of the foundation excavation. Control piles and benchmarks were set up to provide accurate references for subsequent construction.
Foundation Construction: An excavator was used for foundation excavation. After reaching the specified depth according to the design requirements, the base was manually trimmed and leveled to ensure that the flatness and elevation of the base met the design requirements. Then, the concrete cushion layer was poured. During the pouring process, the mix proportion and slump of the concrete were strictly controlled, and a vibrating rod was used for full vibration to ensure the compactness and strength of the cushion layer.
Wall Assembly and Installation
The galvanized steel wire mesh sheets were cut and bent according to the design size on a flat site, and then connected into gabion cages with binding wires at a spacing of 200mm to ensure firm connections.
Starting from the foundation, the assembled gabion cages were installed layer by layer. During installation, a crane was used to lift the gabion cages to the designated positions to ensure the verticality and flatness of the cages. The adjacent gabion cages were spliced in a staggered manner to enhance the integrity and stability of the wall. After each layer of gabion cages was installed, measuring instruments were used for rechecking, and the deviation was controlled within the allowable range.
Filling Stone Construction: Granite with a particle size of 200 – 300mm was selected as the filling stone. The stone filling was carried out by manual work combined with a loader. First, a 300mm-thick layer of small-particle-size crushed stone was paved at the bottom of the gabion cage as a leveling layer, and then large stones were filled. During the filling process, the stones were manually placed to ensure that they were tightly interlocked with each other. When the filling was 200mm away from the top of the gabion cage, small-particle-size crushed stone was used to fill and level it to ensure the flatness and stability of the top surface of the wall. During the filling process, a small vibrating rod was used to vibrate the stones to make the stone filling more compact and improve the bearing capacity of the wall.
