بررسي قانون جريان حاكم بر حركت آب منفذي در آزمايش تحكيم با سرعت كرنش ثابت

Investigation of Flow Regime in Pore Water Flow through Soil in CRS Consolidation Test

The consolidation test method proposed by Terzaghi and used in most soil mechanic laboratories has limitations and weaknesses. To get correct results, improvement and modification of the test method is essential. Several experimental methods, such as constant loading rate, gradient and constant rate of strain (CRS) have been used over the past 40 years. Of these methods, CRS is more advantageous and is more popular, but there is no unique criterion for when to use the test, although many researchers have proposed different methods. Considerable differences exist between standards in the literature. The present study investigates the causes of differences between standards by investigating basic assumptions about flow regime caused by pore water loading during consolidation. CRS consolidation tests were carried out using an MIT consolidometer under different strain rates. The results indicate that a Darcy flow regime is not valid throughout the CRS test, thus, a consolidation equation based on the Darcy flow regime cannot model the test correctly. Also the present research showed three different flow regimes during the test for strain rate, including prelinear (non-Darcy), linear (Darcy low) and postlinear (non-Darcy).