Project of Ecological Restoration (Greening) of a Mountain Slope in Datong City, Shanxi Province, China: Application of Geocell for Slope Reinforcement

Project Background
In 2020, the Lanzhou Municipal Solid Waste Management Department made a decision to expand the existing landfill by adding a new section of the landfill and connecting it with several adjacent older landfills to increase the overall capacity. During the expansion process, it was necessary to comprehensively reinforce the existing slopes to ensure long-term stability. The contractor won the bid for the supply of geosynthetic materials and slope reinforcement works, and selected a professional geosynthetic supplier. The contractor installed approximately 50,000 square meters of geocell reinforcement system on the newly constructed and reconstructed slopes. This system included: a high-density polyethylene geocell (cell height 15 cm, distance between weld seams 40 cm), a 2-millimeter double-sided roughened PEWEP geomembrane, a protective geotextile with a density of 450 g/m², as well as a drainage system for collecting filterate made of PEWEP pipes. Geocell was mainly used for reinforcing the surface of slopes and stabilizing the soil.

Ongoing tasks
For this project, a specialized assessment of slope stability was conducted. The technical requirements clearly specified that the material used for the geomembrane must be tested and meet the relevant standards, especially in terms of the friction characteristics between the geomembrane, the geomembrane itself, and the covering soil. The engineering company demanded that extensive interface shear tests be conducted for the supplied geocell to ensure compliance with all site requirements, specifically point 3. 2.6 Technical conditions: "The interface surface between the geocell and adjacent materials must provide a friction angle of at least 12 degrees and a bonding force of at least 15 kPa, or an equivalent combination of Coulon-Morse strength parameters within the limits of tested normal loads and movements."

Solution
The supplier has completed all the required interface shear tests and provided complete data proving that its geocell significantly exceeds the requirements of the specification (in fact, a friction angle of 14.2 degrees and an adhesion of 18.5 kPa were achieved). All test results were provided on time, which did not affect the progress of the project implementation.

The main problems for the supplier were the complex logistics of delivering materials to the city of Lanzhou and the long delivery times (the geocell has a large volume despite its light weight and requires specialized platform vehicles), as well as the need to ensure work progress during the rainy season. To complete the work on schedule and within the budget, the contractor took advantage of every favorable weather day, increasing the length of work shifts and installing as many geomembranes and geocells as possible. The supplier's logistics department worked closely with the contractor and transportation subcontractors, ensuring the timely delivery of all materials.