1. Introduction

Erosion and landslides caused by the instability of slopes are serious issues, especially common during the rainy season in the mountainous regions of Vietnam, causing significant damage to people and infrastructure. Slopes can be divided into two main types: natural slopes and artificial slopes, with stability depending on various factors such as topography, geological conditions, shear strength of materials, groundwater conditions, and external forces. To effectively protect and stabilize slopes, it is essential to base decisions on detailed surveys to choose appropriate calculation methods and reinforcement measures.

The "grid beam" technology, developed and widely applied by Raito Kogyo in Japan for over 30 years, has proven highly effective in surface protection and slope stabilization. This solution uses a grid beam system constructed using sprayed concrete technology, which both protects the surface of natural or artificial slopes and ensures long-term stability. The grid beam system can be used independently to prevent erosion or combined with soil nails and soil anchors to enhance slope stability, especially for projects requiring high safety standards. By 2002, over 4,600 projects in Japan had applied this technology.

The structure of the grid beam system includes reinforced steel formwork, with typical cross-sectional dimensions of 200 × 600 × 600 mm and a spacing of 1.5 to 3.0 m between beams. To ensure the system’s load-bearing capacity, the intersections of the beams are carefully calculated to withstand maximum tension forces from soil anchors or nails, with load-bearing capacities ranging from 300 kN to 500 kN. The geometric flexibility of the concrete beams allows the grid system to closely follow the surface of the slope, providing a firm and stable connection.

The continuous grid beam solution has many notable advantages, including environmental friendliness as the slope, after construction, can blend harmoniously with the surrounding landscape. This method does not require special construction skills, is easy to implement, and saves time. Furthermore, this system can be applied to high slopes, effectively meeting the complex requirements for slope construction in mountainous and rugged terrain.

2. Scope of application

The shotcrete grid beam system is effectively applied to various types of projects, including:

• Slope protection and stabilization
• Prevention of slope collapse
• Reinforcement of soil cross-sections
• Reinforcement and renovation of existing structures
• Embankment reinforcement
• Restoration of vegetation on eroded slopes

3. Construction sequence

Construction sequence of shotcrete grid beam system is illustrated in Fig. 1.

Figure 1. Construction sequence of shotcrete grid beam system