Research Of Permeability Testing System For Clay

Marine resources and ocean space development and utilization have been increasingly attracted great attention at home and abroad. In order to adapt to this new changes, in recent years, with the rapid development of Chinese economy, our country carryed on a large-scale port construction in coastal areas. Clay is widely distributed in southeast coast, the Bohai Sea and some inland areas of China. For engineering design and construction without in-depth understanding of characteristics of port soil, it will cause the ground instability and enormous loss of life and property. Permeability parameters of clay are important indicator to ensure the solution of design and construction safe, reliable and economical. Therefore, in line with the port engineering design and construction, we must carry on the study of clay permeability.Unlike conventional permeability test, based on Lab VIEW virtual instrument technology development platform, a clay permeability testing system has been builded. It is applied to large-scale permeability test. The system consists of pressure sensors, microcontrollers, serial communications and computer. There will be multiple tube arranged side by side in the test. The pressure signal will be transformed into an electrical signal by the pressure sensor placed in the bottom of test tube, then convert analog signals to digital signals through the A/D conversion device. ATmega8will deal with these data. Meanwhile, ATmega8and ATmega64are connected through the RS-485bus. With the keyboard and LCD, the host microcontroller can display and control each capture device. With the software, ATmega64transform pressure data into level data and connected to PC by serial communication. PC will generate a friendly interactive interface by Lab VIEW virtual instrument software development platform in order to collect and analyze the data as well as storage of historical data, finally, Calculate the permeability coefficient of clay by Darcy’s law.Tests showed that the system is reliable, greatly improved the efficiency compared with traditional penetration test device. It can be applied to large-scale penetration test, provide valid data for the construction.