Search Results (4)

Geocells are widely applied in numerous infrastructure constructions, like heavy-haul railways and ports. The mechanical tearing behavior of a geocell strip is crucial to the stability of the geocell-reinforced soil structures. At present, extensive studies have been conducted on the tensile characteristics of geocell strips, while limited research has been performed to investigate the post-damage mechanical tearing behavior of geocell strips. Meanwhile, there is also a lack of research on the comparison of performance of strips before and after damage. In this paper, a series of trapezoidal tearing tests were performed on high-density polyethylene (HDPE) and polyester (PET) geocell strips. The tearing test results and failure mode of trapezoidal specimens with a slit were investigated, and the effect of the slit on the strength and deformation characteristics of the specimen were discussed by introducing the “damage ratio of tearing force (R_TF)” and “damage ratio of tearing displacement (R_TD)”. In addition, the mechanical tearing behavior of HDPE and PET trapezoidal specimens was also compared. The test results indicated that the failure mode of HDPE and PET specimens subjected to tearing force was ductile and brittle failure. The strength and deformation characteristics of post-damage HDPE and PET trapezoidal specimens decreased. The slit had a significant impact on the tearing displacement of HDPE and PET specimens, especially the post-peak tearing displacement. The post-peak tearing displacement of HDPE was 10.99 times that of PET. The peak tearing force of the HDPE specimen without the slit was about 1.61 times that of specimen with the slit. Before local tearing, the peak tearing force of the PET specimen without the slit was about 3.27 times that of the specimen with the slit. The strength damage to the HDPE and PET geocell strips caused by the slit was 38.0%, and 69.46%. The impact of the slit on the tearing force of the PET specimen was greater than that of the HDPE, and was 1.82 times for the HDPE. This study can enhance our understanding of the mechanical tearing behavior of the geocell strip after damage and develop effective mitigation measures. Full article

Geocells are commonly adopted in various engineering constructions, such as railways and ports. Currently, the reinforcement effects and mechanisms of geocells in engineering is being widely studied, while limited studies have been performed on the mechanical behavior of geocell strips. Uncertainties regarding their performance have impeded the wide application of geocells in engineering fields. In this paper, a series of tensile tests and trapezoidal tests were performed on high-density polyethylene (HDPE) geocell strips. The effects regarding specimen shape, specimen width, and welding junction on the tensile mechanical behavior of HDPE geocell strips were investigated. Additionally, the results of the tensile test and trapezoidal test were also compared. The test results showed that the tensile strength of a HDPE geocell strip was less affected by the specimen shape and specimen width, within 5%. However, the elongation of HDPE strips was sensitive to the specimen shape, and the difference between type I dumbbell and type II rectangular was up to 38%. The effect of the welding junction on the HDPE strip cannot be ignored, the strength retention rate of the welding junction was 76.3%. The curve of the trapezoidal test was similar to that of the tensile test, and the force of trapezoidal test was 0.87 times that of the tensile test. The test results can provide a reference for the testing of strip performance and structural design. Full article

Geocell is widely used in the treatment of poor roadbed, which can restrain soil laterally and improve the stability of soil. In cold area engineering, a change in temperature can influence the mechanical properties of geocell of different materials. To study the mechanical response of geocell at low temperatures, three types of geocell strips commonly used in engineering, namely the polyethylene (HDPE), polypropylene (PP), and polyester (PET), were studied via the uniaxial tensile test at the ambient temperatures of −5 °C, −20 °C, and −35 °C, respectively. Meanwhile, the tensile strength, fracture mode, and temperature sensitivity of geocell specimens were compared. It is concluded that: (1) at low temperatures, the tensile strengths of HDPE and PET geocell strips are significantly improved, while that of the PP geocell strip is less sensitive to the temperature. (2) The PP geocell is subject to a brittle failure at all ambient temperatures. The PET geocell strip experiences a hard-ductile failure at normal temperatures of −5 °C and −20 °C. While in the tensile test at −35 °C, it is prone to brittle failure and hard-ductile failure. The HDPE geocell strip suffers from ductile failure at all ambient temperatures. (3) At low temperatures, overall, the tensile properties of the PET geocell strip is better than those of the PP and HDPE geocell strips. Full article

Geocells are three-dimensional honeycomb-reinforced geotechnical materials composed of strips and junctions. Its junctions can support and transmit forces in several directions. The performance of geocells has a considerable impact on engineering applications. However, the testing program of geocell junctions still lacks standardization, and limited research has been undertaken regarding the failure mechanisms of junctions when subjected to various stress types. In this paper, four test procedures for HDPE welded geocell junctions were performed, including weld tensile, shear, peeling, and splitting strength tests. The influence of tests under different clamping distances (10.5 mm, 25 mm, 50 mm, and 100 mm) was analyzed, and the stress–strain behavior, peak elongation, and peak and residual strength of junctions under various force states were analyzed in detail. Finally, considering the strength and deformation, the slope laying method of geocells was proposed. The results show that the tensile strength and shear strength decrease with the clamping distance, whereas the peeling strength and splitting strength remain essentially unchanged. Under a 100 mm clamping distance, the tensile strength and shear strength are decreased by 4.51% and 14.08%. Geocells spreading vertically along the surface on a subgrade slope are thought to be more reliable, improving the geocell’s service life in slope protection. The test results can be used to improve a standardized geocell junction testing procedure as well as to guide, evaluate, and enhance the quality and application dependability of geocells. Full article