Reinforced segmental block walls showing drainage pipe exits
Placement of reinforced fill on top of MIRAFI
Precast concrete segmental blocks
Reinforcement behind segmental block facing
Cross section through the first three tiers of the reinforced segmental block walls
Omega Mine extends AMD treatment capacity with dewatering
At Omega Mine in West Virginia, GEOTUBE® GT500 units help the West Virginia Department of Environmental Protection treat and dewater acid mine drainage from abandoned mines while supporting long-term capacity and compliance.
Dredging and reuse of contaminated sediments
Embraport used dewatered contaminated sediments as structural fill within its terminal platform, saving 400,000 m3 of imported material and reducing earthfill platform costs by 20% to 30%.
From poor subgrade performance to roadway resilience
MIRAFI H2Rx repairs, weak and cracked roads in traffic-heavy Pulau Indah, Malaysia. MIRAFI H2Rx was installed for separation, mechanical stabilization and moisture management, providing the solution to building durable climate-resilient roadways.
The proposed Yuxi City Municipal Solid Waste (MSW) Incineration Plant involves a total investment of USD 50 million. The site lies at an elevation of about 1,800 m above sea level and is located in rugged hilly terrain of Hongta District, some 30 km from the center of Yuxi City and about 100 km from Kunming City, the provincial capital of Yunnan Province. When completed the incineration plant will manage the MSW not only from Hongta district but also the nearby counties of Eshan and Tonghai. The incinerator is expected to handle 700 tonnes of MSW daily by 2020, increasing to 1,000 tonnes daily by 2030. The incinerator will operate at a temperature of 800 C reducing the MSW to ash with the associated heat energy created used to generate electricity using steam turbine generators. The electricity generated will be sold to the State Grid Corporation of China. The development covers a land area of 7 ha and includes major earthworks, slope stabilization works and construction of retaining walls to create level platforms for the incineration plant, power station and associated ancillary infrastructure.
The natural topsoil layer consists 0.6 m of yellow, brown to red silty clay with traces of limestone gravel and plant roots. Below the topsoil is up to 12 m deep layer of weathered limestone residual gravelly soil. The weathered limestone residual soil sits above a weathered limestone rock formation. The ground terrain is higher in the North and lower in the South. At the Northern boundary of the development site a cut slope was formed with associated slope stabilization works. At the Southern side of the development site a three-tiered retaining wall of about 25 m in total height and over 300 m in length was constructed. At approximately 30 m setback further North a fourth single-tiered retaining wall of 8 m in height and over 350 m in length was also constructed. The site is located in a remote area and was not easily accessed during site construction prior to construction of the paved access roads.
The retaining wall system adopted involved the use of a reinforced segmental block retaining wall system, while using the on-site limestone residual soil for the reinforced fill. The segmental block facing units consisted of wet-cast blocks 0.4 m wide, 0.4 m high and 0.5 m deep. Each block had tongue and groove features at the bottom and the top of each block to enhance the horizontal shear resistance between adjacent blocks and to provide a better connection capacity between the geotextile reinforcement and the block facing. Complementary modular footing and capping units are used. The reinforcement used for the segmental block wall system was MIRAFI® SR geotextile reinforcement having an initial tensile strength of 250 kN/m. MIRAFI SR geotextile reinforcements have good long term performance and are wellsuited for long term reinforced soil applications. Thus, the ability of the retaining wall system to utilize on-site material as the reinforced and platform fill was a huge economical advantage in deciding on the adoption of the retaining wall system. The choice of wet-cast segmental block facing units that could be cast nearby was another plus factor for the wall system adopted. The shape and size of the segmental blocks was also ideal for the project as they could be handled by two workers during placement, without the need for mechanical lifting equipment; but yet large enough to satisfy good facing construction quality and post-construction serviceability design and performance limits. The silty clay topsoil was removed down to the weathered limestone residual stratum and excavated down to the base level of the bottom tier retaining wall. Here, the ground was leveled out and the segmental block footing units were then placed. Next, the base layer of MIRAFI SR2500 geotextile reinforcement was then laid over the segmental block footing units along with the required reinforcement length for laying behind the wall facing. The next facing block was lifted into place manually locking the lower geotextile reinforcement layer in place between the two adjacent blocks. The geotextile reinforcement was then spread out and pulled taut before the reinforced fill was placed over the geotextile reinforcement. The reinforced fill was then compacted to achieve a minimum of 95% of Standard Proctor dry density. When this was achieved, the process was repeated with further layers of geotextile reinforcement, facing blocks and reinforced fill. When the required wall height had been reached the wall was finished with the placement of capping units. Once the first retaining wall tier had been constructed the second and third tiers were constructed in the same manner. These upper tiers were set back 5 m from the crest of each lower tier. After this three-tier retaining wall had been completed a fourth tier was constructed to form the structural fill platform for the incinerator and power station.