Verification of the possibility of reducing the number of the steps of pressure in a compression trial

Purpose. Verify experimentally the possibility of reducing the number of the steps of pressure in a compression trial with a preservation of the quality of obtained results. Methodology. The sandy soils, clayey soils and loessial soils both as a natural building and artificial were tested; their samples were made at rates in the apparatus of standard compacting with a volume 1000 і 200 сm3 with the prescribed physical characteristics (W, rd). Verification was consisted in determination of the difference of deformations to the pressure 400 kPа for two variants of loading ? by six steps in first series of sample-twins and by two steps ? in second series (150, 400 kPа). Results. Continuance of process of the consolidation of clayey soils compeled the researches to seek for the methods of time decrease of the compression trials. The easiest method among them is the quick loading of a sample with designed pressure for the purpose of immediate obtaining of the corresponding squeezings without plotting the entire compression curve, but for all that the big gradients of the interstitial pressure appear and the structure of soil is disturbed more intensively. The famoust comparisons of compression trials for three pairs of the sample-twins of loessial soils in Grozny, Novokuznetsk and Zaporozhye (Abelev Y.M., Abelev M.Y.), in which the first sample was tested by the steps on 10 kPа from zero until 300 kPа, and the second ? on 50 kPа. In the first case the soil was systematically more deformed, according to Abelev Y.M. and Abelev M.Y., and the deviation was on average 41%, and besides the maximal deviations fell on the domains of minimal and maximal pressures. These researches are interesting for our problem, but the small volume of researches (six samples without repetition in the similar trial) don't give the assurance in the terminal conclusion. A suggestion of the replacement of 6-step loading on the 2-step is based both on our data and on the conclusions of Veselovsky V.M. The continuance of the sedimentation of a sample of soil, that was studied in the compression apparatus, don't depend on the value of pression and is a constant for the soil under test of some thickness. Therefore we adhere to the opinion that it is reasonable and can be used in the creation of new method of the determination of the deformative characteristics of dispersible soils. Originality. The possibility of reducing the number of the steps of pressure was confirmed experimentally in a compression trial by the example of 144 samples of soil (city Dnipropetrovsk), if it is necessary to know the deformation just for the pressure 300 kPа. Practical value. The possibility of reducing the steps of pressure was confirmed up to two steps with a preservation of the quality of obtained results. It will appreciably decrease the loss of time and resources on the compression trials. Keywords: reducing of the steps of pressure, compression trials, steps of loading.