The Sandy Ground Volume of the "Constraint" Influence on the Contact Resistance at the Side Surface of a Single Bored Pile

ABSTRACT

The performed research shows that for different conditions for determining contact friction on the side of the foundation, as a rule, for the same non-cohesive soil of different values, sometimes differing by an order of magnitude. “Constrained” dilatancy is the main cause of such significant discrepancies. The phenomenon of “constrained” dilatancy is associated with the mobilization of the contact resistance of the soil to shear and the formation of a layer of destruction with the initial density of the addition of grains of coherent soil. In a narrow strip located along the contact surface, additional stresses are formed, these stresses, associated primarily with the repacking of grains of non-cohesive soil. The influence that the shear conditions have on the lateral surface, for example, piles, incoherent soils themselves, is expressed in the mobilization of contact friction, which, in turn, depends on the state of the incoherent array of non-cohesive soils. Volumetric “constraint” of the soil is affects the formation of contact friction, and this has been proven by us in previous research. In these research, in order to increase the bearing capacity of the pile, we created additional conditions of “constraint” in the form of a submerged thin-walled shell. This shell is located relative to the simulated pile coaxially. We clarified how the contact stresses are distributed along the lateral surface of a single bored pile and was performed by us in the present work using modeling, using the Plaxis 3D Foundation program. The results obtained by us indicate the uneven distribution of contact friction along the lateral surface of a single bored pile. The same results confirm that when the conditions of bulk “constraint” change, the values of contact friction increase.

Keywords: “constrained” dilatancy, stress, non-cohesive soil, bearing capacity, tangent stress.

For citation: Sobolevsky D., Ulasik T., Balysh A. The Sandy Ground Volume of the “Constraint” Influence on the Contact Resistance at the Side Surface of a Single Bored Pile. Contemporary Issues of Concrete and Reinforced Concrete: Collected Research Papers. Minsk. Institute BelNIIS. Vol. 10. 2018. Pp. 250–260. https://doi.org/10.23746/2018-10-16 (in Russian)

References:

1. Design and construction of bored piles : П 13-01 СНБ 5.01.01-99 [P 13-01 SNB 5.01.01-99]. – Activ. 01.01.02. (rus)
2. Eurocode 7.Geotechnical design. Part 1. General rules : ТКП EN 1997-1-2009 [ТКP EN 1997-1-2009]. – Activ. 10.12.09. (rus)
3. Eurocode 7.Geotechnical design. Part 2. Ground investigation and testing : ТКП EN 1997-2-2009 [ТКP EN 1997-2-2009]. – Activ. 10.12.09. (rus)
4. Driven piles. The rules of the designing and device : ТКП 45-5.01-256-2012 [ТКP 45-5.01-256-2012]. – Activ. 01.07.12. (rus)
5. Sobolevsky D. Y. Prochnost I nesushchay sposobnost dilatiruyshchego grunta [Strength and load bearing capacity of the dilating soil]. Minsk: «Navuka I tekhnika», 1994. 232 p. (rus)
6. Ulasik T. M. Herald of Polotsk state university. 2015. No. 16. Pp. 30–33. (rus)
7. Ulasik T. M., Balysh A. V. Herald of Polotsk state university. 2017.No. 8. Pp. 43–48. (rus)
8. Sobolevsky D. Y. Soprotivlenie sdvigu nesvyasnogo grunta po bokovoy poverkhnosti inektsionnykh ankerov I svay [Resistance to shear of non-cohesive soil along the lateral surface of injection anchors and piles]. Вases and foundations in the geological conditions of the Urals. Perm:1987. Pp. 78-85 (rus)
9. Popov, O. The influence of diameter of injection piles on contact friction in non-cohesive soils / O. Popov // Prog. 3-rd International Geotechnical Conference on Soil Mech. and Found. Engin. – Bratislava, 1997. P. 113–114.
10. Sobolevsky, D. Yu. Strength of Dilating Soil and Load-Holding Capacity of Deep Foundations / D. Yu. Sobolevsky // A. A. Balkema publ. – Rotterdam, 1995. 243 p.

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