DEVELOPMENT OF A LOW-COST DIRECT SHEAR BOX MACHINE FOR ASSESSMENT OF SHEAR STRENGTH OF SOILS

Abstract

The shear strength of soils is a critical parameter in geotechnical engineering, influencing the design and stability of structures such as foundations, retaining walls, and slopes. The traditional soil testing methods face challenges related to accuracy, repeatability, and ease of operation. It is against these drawbacks that this paper presents a novel design, development, and fabrication of a direct shear box machine leveraging locally sourced materials to improve precision, user-friendliness, and reliability. A three-stage approach was adopted, which includes the design stage, the fabrication stage, and the assembly, installation, and calibration stage. At the design stage, emphasis was placed on mechanical re-engineering, innovation, automation, and validation against standard testing methods. The development phase considered the choice of tooling, ease of processing, and product quality in carrying out soil tests both in the laboratory and field with minimal stress. The fabrication phase entails the fabrication of parts and components of the designed shear box machine, while the third stage entails the assemblage, installation, and calibration of the fabricated parts and components. The developed device, when deployed for soil testing results showed a linear relationship, such that as the load increases, the deflection increases in a similar manner, and was found to be consistent with the expected statutory range with superior performance in terms of precision, accuracy, and repeatability. The developed machine cost N1,700,000.00 as against the importation price, which stood at N2,500,000.00, leading to a saving of N800,000.00. This innovative device is therefore a good substitute for traditional approaches and also a source of internally generated revenue for Olusegun Agagu University of Science and Technology, Okitipupa, Ondo State, Nigeria.