A large direct shear machina for static and dynamic shear strength testing of geosynthetic clay liners (GCLs) and GCL liner systems is described. The machine tests rectangular GCL specimens measuring 305 × 1067 mm and has a maximum shear displacement of 254 mm, which is sufficiently large to allow for the measurement of residual or near-residual shear strengths in most cases. The basic design concept for the device is to shear a GCL specimen between a bidirectional pullout plate and a stationary reaction plate, each covered with an aggressive gripping surface. The pullout plate is driven by a computer-controlled hydraulic actuator. The maximum normal stress is 2000 kPa, the maximum shear stress is 750 kPa, and the shearing system is capable of imposing general stress-controlled or displacement-controlled dynamic loading to a test specimen. The actuator has a maximum frequency of 4 Hz for sinusoidal loading with a displacement amplitude of 25 mm. The maximum displacement rate for burst loading (i.e., single thrust) at zero force is 1 m/s. The paper describes four main components of the machine: (1) the shearing system; (2) the normal stress and vertical displacement measurement system; (3) the specimen hydration system; and (4) the process control and data acquisition system. The performance of the machine is illustrated using displacement-controlled test data for the static and cyclic internal shear strength of a hydrated needle-punched GCL.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.