DETERMINATION OF THE LOAD-BEARING CAPACITY FOR DRILLING PILES CONSIDERING THE COEFFICIENT OF THE SOIL POROSITY

Abstract

The influence of the coefficient of porosity of sandy soils on the bearing capacity of drilling piles according to the results of their static tests in field conditions is analyzed.  Piles of different lengths were tested.  The pile lengths are in the range of 2 to 12.0 m. The diameter of the pile trunk is in the range of 0.4 m to 0.83 m. The load, which can be sustained by a specific drilling pile, was determined when the settling limit s = 40 mm.  It is established that the method of determining the bearing capacity adopted in the applicable standards corresponds to sandy soils with a high porosity coefficient, therefore, at low porosity coefficients, the real bearing capacity exceeds the one determined by the standards.

 A table is proposed to determine the specific soil resistance on the lateral surface of the pile, taking into account the porosity coefficient.  To solve this problem, we used the geotechnical software complex "Plaxis 3D Foundation", which simulated the stress-strain state of the drill pile in sands of different size and density.  14 types of sandy soils were modeled with a change in the porosity ratio from 0.45 to 0.75.

 The results of the calculations using the proposed table are compared with the results of static testing of drilling piles.  The results showed better compliance with the test data compared to the norm methodology.