Reflected waves from bored or CFA piles of large section in the offshore soils

UDK: 624.501
Key words: wave processes, bored piles , rarefaction wave, elastic waves, elasto-plastic waves, offshore soils, pressure
Authors: L.F.Aslanov (Azerbaijan University of Architecture and Construction, the Republic of Azerbaijan,Baku)
The problems of the reflection of the waves on the surface of the pile foundation, from the most dense weakly compressible shelf base and in water are considered. The parameters of the reflected wave at the piles of large section with "hard core" are determined. The design parameters of the reflected wave of bored-bit or CFA piles of large cross section that are required for the calculation of offshore structures subjected to the dynamic effects of different types of waves are determined. The grounds of pile foundations consisting of most dense (less compressible) shelf clay soils (solid or semi-solid clays) are considered. This medium is relatively more compressible than the surface of the pile, but less compressible then ground base underlying layer of soil. Soil is taken as ternary medium consisting of air, water and solid particles. Each component is determined separately and the ratio of parameters of air in the composition of the soil to the total volume is calculated. In the presence of entrapped air in offshore soil rheological model of soil describing the non-linear properties is used. Reflection of waves from a large section constructions of the pile depending on the soil properties and shelf-pressure in the incident wave are determined by the reflection coefficient. The underlying layer or the second medium in front of the shock wave is considered as a special case. Under the shock wave this weak second layer stays fixed. The approximations method is implemented.
References
1. Gel'fand B.B., Gubin S.A., Timofeev E.I., Reflection of plane shock waves
from a solid wall in the system of gas bubbles - liquid (In Russ.), Izvestiya AN
SSSR, 1978, no. 2, pp. 174–178.
2. Lyakhov G.M., Polyakova N.I., Volny v plotnykh sredakh i nagruzki na
sooruzheniya (Waves in dense media and loads on structures), Moscow:
Nedra Publ., 1967, 232 p.
3. Il'ichev V.A., Dinamicheskoe vzaimodeystvie sooruzheniy s osnovaniem i
peredacha kolebaniy cherez grunt. Spravochnik proektirovshchika. Dinamicheskiy
raschet sooruzheniy na spetsial'nye vozdeystviya (Dynamic interaction
of structures with base and transfer of vibrations through the
ground. Designer Handbook. Dynamic calculation of structures for special effects),
Moscow: Stroyizdat Publ., 1981, pp. 144–148.
4. Aslanov L.F., Kombiniron reologicheskim model za opisane na lineyno elastichno
napregnato s"stoyanie na shel'fa (A comprehensive rheological model
for description of linear-elastic stress state of the shelf), Proceedings of VI International
Scientific Conference “Arkhitektura, stroitel'stvo – s"vremennost” (Architecture,
Building - Present), 30 May – 1 June 2011, Varna, 2011, pp. 159–167.
5. Aslanov L.F., Raschet pontona i vsplytiya opornogo bloka pri razlichnykh
glubinakh morya dlya osvoeniya neftegazovykh mestorozhdeniy (Calculation
of the pontoon and surfacing of the support unit at different depths of
the sea for oil and gas field development), Proceedings of International scientific
and practical conference, Gelendzhik, 2010, pp. 67–72.
6. Aslanov L.F., Process of two-dimensional waves and their impact on pile
foundations during the construction of offshore structures (In Russ.), Vestnik
Saratovskogo gosudarstvennogo tekhnicheskogo universiteta, 2013,
no. 3(72), pp. 163–167.
The problems of the reflection of the waves on the surface of the pile foundation, from the most dense weakly compressible shelf base and in water are considered. The parameters of the reflected wave at the piles of large section with "hard core" are determined. The design parameters of the reflected wave of bored-bit or CFA piles of large cross section that are required for the calculation of offshore structures subjected to the dynamic effects of different types of waves are determined. The grounds of pile foundations consisting of most dense (less compressible) shelf clay soils (solid or semi-solid clays) are considered. This medium is relatively more compressible than the surface of the pile, but less compressible then ground base underlying layer of soil. Soil is taken as ternary medium consisting of air, water and solid particles. Each component is determined separately and the ratio of parameters of air in the composition of the soil to the total volume is calculated. In the presence of entrapped air in offshore soil rheological model of soil describing the non-linear properties is used. Reflection of waves from a large section constructions of the pile depending on the soil properties and shelf-pressure in the incident wave are determined by the reflection coefficient. The underlying layer or the second medium in front of the shock wave is considered as a special case. Under the shock wave this weak second layer stays fixed. The approximations method is implemented.
References
1. Gel'fand B.B., Gubin S.A., Timofeev E.I., Reflection of plane shock waves
from a solid wall in the system of gas bubbles - liquid (In Russ.), Izvestiya AN
SSSR, 1978, no. 2, pp. 174–178.
2. Lyakhov G.M., Polyakova N.I., Volny v plotnykh sredakh i nagruzki na
sooruzheniya (Waves in dense media and loads on structures), Moscow:
Nedra Publ., 1967, 232 p.
3. Il'ichev V.A., Dinamicheskoe vzaimodeystvie sooruzheniy s osnovaniem i
peredacha kolebaniy cherez grunt. Spravochnik proektirovshchika. Dinamicheskiy
raschet sooruzheniy na spetsial'nye vozdeystviya (Dynamic interaction
of structures with base and transfer of vibrations through the
ground. Designer Handbook. Dynamic calculation of structures for special effects),
Moscow: Stroyizdat Publ., 1981, pp. 144–148.
4. Aslanov L.F., Kombiniron reologicheskim model za opisane na lineyno elastichno
napregnato s"stoyanie na shel'fa (A comprehensive rheological model
for description of linear-elastic stress state of the shelf), Proceedings of VI International
Scientific Conference “Arkhitektura, stroitel'stvo – s"vremennost” (Architecture,
Building - Present), 30 May – 1 June 2011, Varna, 2011, pp. 159–167.
5. Aslanov L.F., Raschet pontona i vsplytiya opornogo bloka pri razlichnykh
glubinakh morya dlya osvoeniya neftegazovykh mestorozhdeniy (Calculation
of the pontoon and surfacing of the support unit at different depths of
the sea for oil and gas field development), Proceedings of International scientific
and practical conference, Gelendzhik, 2010, pp. 67–72.
6. Aslanov L.F., Process of two-dimensional waves and their impact on pile
foundations during the construction of offshore structures (In Russ.), Vestnik
Saratovskogo gosudarstvennogo tekhnicheskogo universiteta, 2013,
no. 3(72), pp. 163–167.


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