(1) Stabilizing Railway Subgrades and Soft Road Foundations
Geocells perform excellently in stabilizing railway subgrades and soft road foundations. They can prevent the lateral movement of crushed stones and graded aggregates, making the whole structure more solid, prevent water pumping, and can prevent overall or local collapses even when the foundation is soft. In areas with heavy traffic such as intersections, branch roads and turning lanes, they can significantly increase the service life. For example, in a performance study on high-density polyethylene geocells in Japan, a cushion layer structure subgrade with a thickness of 30 cm was formed by geocells with 10 cm of crushed stones on the upper part and 20 cm of filled crushed stones on the lower part. Compared with the traditional replacement and filling construction method, it could achieve the same standard subgrade thickness. In addition, similar domestic products have been successfully used to reinforce soft foundations on the Huainan Line and the Southern Xinjiang Railway.
(2) Withstanding Heavy Embankments and Retaining Walls
Geocells can firmly withstand heavy embankments and retaining walls. They define and reinforce crushed stone masses, form a consistent structural body, can resist lateral pressure, can adjust themselves regardless of stratum sliding and cohesion, can support non-structural surfaces and natural vegetation layers, and can be designed vertically or in a stepped manner. For example, in the geocell road construction test carried out by the Marine Engineering Research Institute of the Liaohe Oilfield Survey and Design Institute on the exploration road in the intertidal zone of the beach, two layers of 20-cm-high geocells were used, along with geotextiles as the bottom layer of the subgrade. The lower geocells were filled with coarse sand and gravel, and the upper ones were filled with slag. Mountain rubble was used as the shoulder on both sides. After being soaked by the tide and undergoing natural settlement, large heavy-duty dump trucks could run on it without rolling, reflecting the characteristics of high structural strength, good integrity and strong ability of uniform load diffusion of the geocell and slag pavement structure.
(3) Strengthening Pipeline and Sewer Support Structures
Geocells can be used to strengthen pipeline and sewer support structures. By using honeycomb geocells, it is not necessary to excavate and place a large number of stones as the support structure for pipe beds or sewers. Using conventional materials, a solid and durable integral slab structure can be formed to provide flexible protection for pipelines, reduce the slight subsidence caused by long-term use, make the foundation of pipelines more solid, and prevent local collapses for a long time. This construction method is simple and convenient, reduces excavation, and is more economical and practical for long-distance large-scale transportation pipelines.
(4) Preventing Debris Flows and Creating Solid Mixed Barriers with Strong Bearing Capacity
Geocells are used to prevent landslides and create mixed retaining walls with load-bearing capacity. Without using formwork, a solid wall surface can be created and firmly integrated with the backfill. Even in situations where traditional gravity structures cannot be used, the fill material can be sourced locally, significantly reducing the project cost.
(5) Stabilizing Independent Walls, Wharves, Embankments, etc.
Geocells can quickly construct independent walls or barrier walls, and can use permeable granular fill embankments or weir walls. If temporary facilities need to be removed, geocells can also be recycled. They are also widely used in wharves, flood embankments and other important coastal applications.
(6) Treating Deserts, Beaches, Riverbeds and Riverbanks
In desert road construction, due to the loose foundation in the desert, the lack of commonly used road construction materials in the uninhabited area, road construction is difficult and the cost is high. By using geocells, the geocells can be directly pulled open and fixed on the desert, and then filled with sand and stones by using local materials. The operation is simple and the efficiency is high. The constructed road surface can meet the long-term use of various heavy-duty vehicles. In addition, it can be reused when used as a desert exploration road. For example, the Xi'an Highway Institute cooperated with the Road Construction Engineering Company of the Huabei Petroleum Administration Bureau to conduct applied research on desert road construction using geocells developed by the Anti-corrosion Technology Research Institute. The obtained compressive resilient modulus reached 190 - 210 MPa, fully meeting the subgrade design requirements. Moreover, the geocell sand-filled structural layer was about 10 cm thinner than the natural gravel structural layer, and local materials could be used.
In beach intertidal zone road construction, road construction in the beach intertidal zone is a very difficult task and requires large infrastructure projects like moving mountains and filling seas. However, it is easy to combine geocells with geotextiles. The geotextiles are laid flat on the beach, and then the geocells are placed on them. After being fixed, sand and stone materials are put in and compacted to form a road, and the strength of the road will not be affected even if it is flooded by the tide.
In terms of river channel regulation, honeycomb geocells play an effective role in river channel improvement. The three-dimensional grid can enhance the filling force, prevent soil erosion, increase the load, reduce the construction cost of shallow rivers, and enable river crossing design for traffic and soil engineering structures.
(7) Dealing with Special Sections Such as Cut-and-Fill Subgrades
When constructing embankments on slopes where the natural ground slope is only 1:5, steps should be excavated at the embankment foundation. Geocells can play a lateral confinement role for loose fillers, ensuring that the subgrade has high stiffness and strength within a limited height to withstand the load stress of large vehicles and better solve the problem of uneven settlement. In the connection section of cut-and-fill of high-fill subgrades, geocells can solve the cracks that appear at the junction of cut and fill and handle the connection problem of subgrade settlement layers with different rates. In dealing with vehicle bumping at bridge abutments, in areas where silty soil and sandy soil are predominant along the whole line, using geocells to make differential settlement transition sections can specifically treat the common problem of "vehicle bumping at bridge abutment", and the effect and service life are multiplied. In the treatment of soft soil foundations, after using geocells, the construction intensity can be greatly reduced, the amount of work can be decreased, the bearing capacity of the subgrade can be improved, the construction efficiency can be increased, and the investment cost can be significantly reduced. For example, in a patent for a soft foundation reinforcement structure and its reinforcement method applied by the Design General Institute, it includes two sets of blocking components arranged in parallel on the soft foundation, and a geocell layer is set between the two sets of blocking components. The top of the reinforcement piles is fixedly connected with reinforcement layers distributed on the top and bottom of the geocell layer, effectively avoiding the deformation of the soft foundation at the bottom of the subgrade and improving the stability of the soft foundation. In the construction method of using geocells to reinforce soft rock subgrades, steps such as leveling the soft rock subgrades to be reinforced, paving geocells, filling geocell reinforced layers, and conducting the second leveling treatment are carried out, which has the characteristics of simplicity and strong operability. When encountering soft foundations on expressways, using geocells can greatly reduce the labor intensity of construction and reduce the thickness of the subgrade.
