Trong thử nghiệm nén ba trục sử dụng trong cơ học đất, ba thông số cần phải được theo dõi: áp lực, di dời và thoát âm lượng trong khi thời gian thử nghiệm. Khối lượng thoát nước trong khi thử nghiệm dòng chảy qua một ống thẳng đứng đi kèm với một người cai trị. Áp lực và sự di chuyển được chỉ định bởi các đồng hồ đo. Trong hoạt động hướng dẫn sử dụng, các thông số này được ghi lại bởi giám khảo sau khi thời gian nhất định | TẠP CHÍ PHÁT TRIỂN KH CN TẬP 11 SÓ 03 - 2008 DEVELOPMENT OF AN AUTOUMATIC DATA PROCESSING FOR TRIAXIAL COMPRESSION TEST Pham Hong Thom 1 Le Minh Son 2 Phan Tan Tung 1 Nguyen Tan Tien 1 l University of Technology VNU-HCM 2 Survey Construction Company Hochiminh City Manuscript Received on November 01st 2007 Manuscript Revised March 09th 2008 ABSTRACT In triaxial compression test using in soil mechanics three parameters need to be monitored pressure displacement and drainage volume during testing time. The drainage volume during the test flows through a vertical pipe which accompanied with a ruler. Pressure and displacement are indicated by gauges. In manual operation these parameters are recorded by examiner after certain duration. This paper studies on developing an automatic data processing for automatic recording these parameters. A camera is used to track the drainage level then its volume is determined. Digital pressure sensor and displacement sensor are used to measure pressure and displacement. Two PIC 18F458s are used to receive signals from sensors and connect to PC through RS232. The test results in the required forms are given using software. Experiment has been done to verify the proposed solution. 1. INTRODUCTION A typical geotechnical engineering project begins with a site investigation of soil and bedrock on and below an area of interest to determine their engineering properties including how they will interact with on or in a proposed construction. Examining of soil properties especially in shear stress is indispensable to understanding of the area in or on which the construction will take place. There are two main kinds of the test direct shear test and triaxial test. Direct shear test is used to find the shear strength parameters of soil quickly. In direct shear test only the stresses at failure are known whereas in the triaxial test the complete state of stress is assumed to be known at all stages during the test. Therefore triaxial test is .
