Cement Pile Research Articles

Application Research on Composite Foundation of Rammed Soil-Cement Piles Applied in the Da-Guang Expressway from Gu'an to Shenzhou

Through the practice of tamped cement soil pile in treatment of soft soil foundation in Guan to Shenzhou section of Daqing-Guangzhou Expressway, the author expounds the action mechanism of rammed soil cement pile, composite foundation design points and calculation method of bearing capacity characteristic value.

Use of steel and polypropylene fibers to improve flexural performance of deep soil–cement column

In this study, steel and polypropylene fibers are used to improve flexural performance of soil–cement pile. Deep cement mixing (DCM) technique has been used for decades in Thailand to improve the strength of soft clay in Bangkok and vicinity. However, since it is made of about 10–20% of cement, it also shares similar properties as the harden cement such as good compressive strength, low permeability, and poor tensile and flexural strengths (brittle). In several occasions when subjected to bending moment caused by horizontal loadings (induced by large embankment), the poor flexural strength can lead to a failure of the soil–cement column. In order to improve its flexural strength and brittleness, a technique of mixing short fibers (similar to that used in conventional concrete) is introduced to the soil cement mixture. Two types of fiber are used to produce the fiber reinforced soil cement (FRSC): polypropylene and steel fibers at three different volume fractions of 0.5%, 0.75% and 1.0%. Flexural performance of the FRSC is carried out according to ASTM C1609. Results show improvements in the flexural performance as seen by the increase in the equivalent flexural strength ratio and the residual strength when the fibers are incorporated into the mix. The polypropylene fiber is found to perform better than the steel fibers. With the increasing volume fraction, the toughness is also increase.

Experimental Study on Nondestructive Monitoring of the Defects in Tamping Soil Cement Piles with Ground Penetrating Radar

In this paper, , the combination of antenna array detection method of ground penetrating radar is put forward to solve the actual engineering problem that is difficult to monitor the integrity of the flexural pile composite foundation. The experiments of defects of six tamping soil cement piles find that the relative error of the pile position of defects is 5.25%. The result indicates that it is enough reliability to determine the pile defects by using the GPR method and can meet the engineering needs. Furthermore, the effect of age of cement, the ration between soil and cement, depth and types of defects on the monitoring quality is obtained.

Full-scale reinforced embankment on deep jet mixing improved ground

A 6 m high reinforced embankment constructed on deep-mixing improved soft Bangkok clay is presented. The jet mixing method with cement slurry employing a jet pressure of 20 MPa was utilised in the installation of deep mixing piles. Surface settlements and lateral movements were monitored during and after construction. The deep mixing improvement has effectively reduced the settlement by as much as 70%. The differential settlement between pile and soil ranged from 8 to 20% of the average settlement. Moreover, the back analysis confirmed the laboratory investigation that the soil–cement pile installed by jet mixing can have a higher after-curing void ratio and, consequently, higher permeability and coefficient of consolidation. Finally, the higher permeability ratios, Kv,p/Kv,c, of 30 and 40 were confirmed from numerical and analytical back analyses, respectively. Une berge renforcée de 6 m de hauteur, construite sur une argile tendre de Bangkok améliorée par mixage profond fait l'objet de cette étude. Nous avons utilisé la méthode de mixage par injection de ciment liquide, sous une pression de 20 MPa, dans l'installation de piles à mixage profond. Les affaissements de surface et les mouvements latéraux ont été suivis pendant et après la construction. L'amélioration par mixage profond a effectivement réduit de 70% l'affaissement. L'affaissement différentiel entre pile et sol représente 8 à 20% de l'affaissement moyen. De plus, la rétro-analyse a confirmé l'étude en laboratoire montrant que la pile sol-ciment installée par mixage à injection peut avoir un taux de pore plus élevé après cuisson et, en conséquence, une perméabilité et un coefficient de consolidation plus élevés. Enfin, des taux plus élevés de perméabilité, Kv;p/Kv;c, de 30 et 40, ont été confirmés par les rétro analyses numériques et analytiques respectivement.

Construction of Paramithia tunnels, Egnatia motorway, Greece

The paper describes in detail the construction process followed for site set-up, portal formation, tunnel excavation and primary lining of two tunnels in the presence of heavily fragmented cataclastic material. Excavation techniques used to secure the crown of the tunnel and to avoid extensive collapses included, inter alia, grouted forepoles of various types and density, down the hole drilling, the use of self-drilling anchors and fibre-reinforced shotcrete. The optimum set of measures was selected according to block size, interlocking of blocks and cohesion of each unit at the tunnel crown and sides. Attention is paid to the observational method applied, the treatment of special cases with novel techniques such as horizontal cement piles and the treatment of localised ground collapses, and to the production rates achieved during construction. A procedure applicable when mixed conditions at the tunnel face are encountered during excavation in tunnelling projects is proposed.

New consolidation equation for soil–cement pile improved ground

During the consolidation process of a soil–cement pile unit cell, the excess pore pressure of the pile cannot be assumed to be zero at any given time. However, the higher coefficient of consolidation and coefficient of permeability of the soil–cement pile relative to that of the surrounding clay allows its excess pore-water pressure to dissipate quickly. This subsequently creates a hydraulic gradient with the adjacent surrounding clay and allows the pore water from the latter to flow radially. While the consolidation process of the soil–cement pile controls the radial drainage of the pore water into the surrounding clay, the entrance of the pore water from the surrounding clay also subsequently alters the consolidation process of the pile. A new governing equation that describes the interdependent consolidation of the pile and its surrounding clay in a typical unit cell of soil–cement pile improved ground has been derived. Solutions to this governing equation corresponding to two extreme compatibility conditions of load transfer device, namely, equal stress and equal strain conditions, are presented. Moreover, the procedure to estimate the consolidation of this improved ground when it is loaded through a partially rigid load transfer device is also discussed. Finally, design charts are generated and one case history is analyzed to verify the use of this new governing consolidation equation.Key words: soil–cement pile, consolidation, compressibility, ground improvement, unit cell.

Deep soil mixing used to reduce embankment settlement

Severe settlement and stability problems characterize the problems of the 55 km Bangna–Bangpakong Highway in Thailand. To rehabilitate this major arterial road, the deep mixing method (DMM) with soil–cement using ordinary Portland cement has been utilized for foundation improvement. In the laboratory, trial mix designs were used with a specified unconfined compressive strength of 1000 kPa. In the field, the unconfined compressive strength of the cement piles was specified at 600 kPa. Detailed soil investigations and subsequent evaluations for Section 3 from km 28 + 000 to km 34 + 500 were done. Analyses were performed regarding the bearing capacity, total settlements and their rates, and stability analyses. The predicted vertical and horizontal deformations were compared and generally agreed with the corresponding values observed in the field.

Observations on Patella Vulgata. Part II. Rate of Growth of Shell

SUMMARYMany common limpets Patella vulgata, settled and grew on the cement piles of a new wharf constructed at Plymouth. Each pile or part of this wharf provided experimental material for the determination of the maximum age of the limpets which grew thereon, as the dates of completion were known. It was found that at an age of about one year limpets grew to lengths of 26 to 35 mm. in 1912, and to at least 11 to 27 mm. in 1913 :and at an age of two years to at least 53 mm. in 1911-1913, and to 47-49 mm. in 1912-1914.The shells were of the mid-tide-level type, and were low, broad, and rather thin. It is considered that such growth in length is unusual, and is correlated with the habitat and favourable climatic conditions. In the same situation in 1913 marked limpets grew from January 27 to September 2, respectively, 20 mm. (from 21 to 41) and 15 mm. (from 38 to 53), and showed arrest of growth in midsummer.Other marked limpets showed arrest of growth in the winter period, and many at lengths of about 25 mm. an arrest of growth independent of any season of growth. Seasonal shell-growth is discussed briefly ; a postbreeding shell-growing period is general in spring and early summer, but it is not known whether a midsummer resting-period is general among individuals more than one year old. Ad hoc investigations are suggested in combination with work on sex and spawning.A preliminary notice is given of investigations into the cause of variation in shell-height, wherein it is shown that shell-height is determined probably entirely by the degree of exposure of limpets to desiccation, in such a manner that the drier the habitat the higher the shell is. Limpets submerged at neap tides have a relatively uniformly low shell, those exposed at high-water neaps have a relatively high shell, which is higher in the drier than in the damper situations, apparently irrespective of exposure to wave-action.

Sex-Phenomena in the Common Limpet: (Patella vulgata)

IN the course of investigations on the rate of growth and the age at which breeding begins the common limpet was examined, and the following interesting phenomena were observed:—A preliminary examination of batches of limpets of about 2 cm. long, and later still of smaller specimens, revealed the occurrence of a large proportion of males. The proportion of males was so high indeed as to give strong suspicions of a change of sex from male to female (i.e. protandric hermaphroditism), and a sample of about 1000 small ones less than 1 in. was therefore collected from cement piles between 3 ft. and 9 ft. above low-water springs at the Great Western Docks, Plymouth, and the sex examined and recorded. As the common limpet has no penis or uterus, it is necessary to examine the internal sex-organ (the gonad) to determine the sex. Of the 1102 limpets collected, 167 were rejected as being found by experience to be too small to show development of the internal sex-organ; these were mainly about 13 mm. long. Of the remainder, 169 (mostly about 14 mm.) showed no development of gonad on examination, 64 were females mostly about 2 cm. long, and the remaining 702 were males mostly about 15 mm. to 20 mm. long. These males probably comprise the bulk of the limpets in this sample in their first spawning year.