Hotel Foundation Construction in Soft Ground in Atyrau Cottage Settlement, Kazakhstan Republic l2

A.V. Anikjev, Ph. D., Technical Director, Scientific & Production Firm Fundament'sirviproject LLC, Russia; V.Y. Shishkin, Ph. D., Senior Expert, State Unitary Enterprise NIIOSP (Research Institute of Bases and I underground Structures) named after NM. Gersevanov, Russia; .Y. Sapozhnikov, General Director, Closed JSC TengizInterNefteGazStroi, Kazakhstan

ABSTRACT: Piles of four kinds have been manufactured with the use of various technologies under difficult engineering and geological conditions specific for the construction site. Optimal structures have been selected according to the results of static tests performed on eight piles. Application of grillage with an intermediate Cushion has been considered for a construction site with seismicity level - 8.

Construction site is located near the University in the town of Atyrau, on the right-bank terrace of the Urals river. Ground water available on 1.0-1.8 m depth is highly saline, aggressive against Portland cement. The construction site is formed by the following layers (from the surface to the bottom):
•    Fill-up soil. Layer thickness - 0.6-2 m.
•    Clay sand - plastic up to fluidity. Layer thickness - 12.4- 12.7 m.
•    Hard clay. Exposed bed thickness -7 m. Soils are aggressive against sulfate-resistant cement According to the technical report provided by Atyrau Oblast   Geotechnical    Center   GHZ,   regional leismicity level is 8.

I lie hotel is a seven-storied building with a one-two-itoried stylobate part. The central part has load-bearing frame structures, cast-in-place reinforced Concrete walls and cast-in-place stiffening core. Cast-in-place floors are girderless. Stylobate part contains cast-in-place reinforced concrete columns and cast-in-place reinforced concrete floor disks. Maximum vertical load on the central core: N=27500 kN, horizontal - 6530 kN for 8 seismicity level and 1580 kN for 7 seismicity level.

The   analysis   of  engineering   and   geological conditions   of  the   construction   site,   building structures and existing loads showed the necessity of pile foundation construction.

In order  to  develop  optimal  pile  foundation structures,   piles   of   four   kinds   have   been manufactured with the use of various manufacturing technologies.

The procedure of SI type cast-in-place pile construction was as follows:

• drilling of a 15 m deep well (d=400 mm),
• with clay flushing;
  
• reinforcing cage installation;
  
• well filling with V20 grade fine-grained oncrete through an injector pipe sunk up o the well bottom;

DIAGRAM OF SETTLEMENT (S) DEPENDENCE UPON S1 TYPE PILE LOAD (P)

Diagram 1

The procedure of S2 type concrete-filled pipe pile construction was as follows:

sinking of a pipe closed at the bottom end (d=219 mm) with the help of SO-166 pneumatic hammer up to design pile refusal (1=15 m);

well filling with V20 grade fine-grained concrete through an injector pipe sunk up to the well bottom; reinforcing cage installation;

DIAGRAM OF SETTLEMENT (S) DEPENDENCE UPON S2 TYPE PILE LOAD (P)

Diagram 2

The procedure of the construction of S3 type bored injection pile with a densified bottom was as follows:

• drilling of a well (d=400 mm) that is 2 m shorter than design depth (1=15 m);
• well filling with cement mortar (Water/Cement=0.6) through an injector pipe sunk up to the well bottom;
• installation of a closed-end pipe (d=219 mm) with a widened bottom part (d=325 mm);
  
• pipe sinking with the help of SO-166 pneumatic hammer up to design pile refusal;
  
• reinforcing cage installation;
  
• well filling with fine-grained concrete.
  

DIAGRAM OF SETTLEMENT (S) DEPENDENCE UPON S3 TYPE PILE LOAD (P)

Diagram 3

S4 type cast-in-place piles were constructed according to SI pile construction technology, only the diameter of a bored well was 250 mm.

DIAGRAM OF SETTLEMENT (S) DEPENDENCE UPON S4 TYPE PILE LOAD (P)

Diagram 4

Corrosion resistance of fine-grained concrete was provided by the use of additives increasing its water resistance to W16 grade.

Photo 1

Photo 2

Foundation with an intermediate cushion was designed for the construction site with 8 seismicity level due to considerable horizontal strain caused by a special combination of loads. According to the conclusion made by Atyrau Geotechnical Center KazGIIZ, design seismicity of the construction site was revised and accepted as 7. Therefore, pile grillages were designed without considerable increase of piles bearing special combination of horizontal loads.

Conclusions:

1.    Design load on a SI type cast-in-place pile (d=400 mm) is equal to 510 kN, and design load on a S4 cast-in-place pile (d=250 mm) is 350 kN. However, S4 type piles utilization is limited by the construction site seismicity level equal to 6.

2.    Design load on S2 type concrete-filled pipe  (d=219 mm) is 315 kN. Sinking of a pipe (d=219 mm, 1=15 m) with the help of an SO-166 pneumatic hammer took 15 minutes under the described soil conditions.

3.    Design load on a S3 type cast-in-place pile with a densified bottom is 445 kN.

4.    Technical and economic comparison of the options showed that SI and S2 type piles utilization is optimal under the given conditions of construction.