مطالعه متغيرهاي شكل پذيري آبرفتهاي درشت دانه تهران با استفاده از پرسيومتر منارد

The study of deformation parameters of coarse grained alluvium of Tehran using Menard Pressuremeter

The most parts of Tehran area has been covered by coarse-grained alluvium deposits. So far, it has been difficult to obtain accurate strength and deformation parameters of the alluviums using laboratory and conventional in-situ tests. The presented paper explains the problems exist on using Menard pressuremeter in Tehran coarse-grained alluviums, from execution point of view including the preparation of test pocket and operation, and proposes the adequate method. In addition the paper studies the shear moduli of this soils, obtained from Menard pressuremeter, plate loading and shear wave tests. The studies show that the shear moduli of cemented alluvium is, in average, 1.7 to 2 times greater than uncemented one. Also, the shear moduli increase with depth of tests, and the rate of increase is more rapid for cemented one than uncemented. However, because of strain level dependency of shear modulus, the shear moduli obtained from pressuremeter are smaller than plate loading and very smaller than shear wave moduli. The stress-strain behaviour of Tehran alluvium soils, as expected, is non- linear.