Short Piles Research Articles

根入れ長さが杭の水平挙動性状に及ぼす影響の実験的検討

The purpose of this paper is to investigate the effects of pile head condition and pile length on the behavior of laterally loaded piles in sand. The tests were carried out on single piles by using test apparatus which was especially desinged to apply both of fixed and free head conditions. Based on the results of the model tests, Broms' assumption of the ultimate soil resistance equal to three times the Rankine passive pressure for sand is examined, and classifying into "long pile" and "short pile" modes in the method of the estimating ultimate lateral resistance of single piles is also discussed.

Use of short piles and slab foundations in residential construction on weak foundation beds

Use of short piles and slab foundations in residential construction on weak foundation beds

Bearing capacity of bored short piles : Pula, O; Rybak, C Proc 1st International Geotechnical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7–10 June 1988P467–470. Publ Rotterdam: A A Balkema, 1988

Bearing capacity of bored short piles : Pula, O; Rybak, C Proc 1st International Geotechnical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7–10 June 1988P467–470. Publ Rotterdam: A A Balkema, 1988

Design of piles in swelling soils

The complete or partial penetration of soil by piles is one of the effective methods of building on swelling soils, which are widespread in Povolzh'ye, Kazakhstan, Siberia, Crimea, and Zakavkaz'ye where many lightly loaded agricultural buildings are raised on them (1). The interaction between piles and swelling soils is distinguished by characteristic peculiarities. When a frozen swelling soil rises, the pile is displaced upward, and when wetted, its strength characteristics and the bearing capacity of the piles are diminished. The length of the piles should, in conformity with standards (2), be assigned proceeding from conditions whereby the bearing capacity is guaranteed and their uplift does not exceed the allowable value for the structure. The first condition is verified by computing the bearing capacity with allowance for the reduction in the resistance of the swelling soil against the lateral surface. The soil's coefficient of strength reduction is set equal to 0.5 for all conditions, although in our opinion, it should be differentiated as a function of the type of soil and the pile structures. It is expedient to compute the bearing capacity on the basis of allowable pile settlements with allowance for slump-type settlements of the swelling soil. A method of calculating pile uplift, where the effect of the type of swelling soil and pile length is defined more precisely, is cited in (2) for evaluation of the second condition. According to E. A. Sorochan, V. S. Sazhin et al., the shape and geometric dimensions of the pile's section, the type of pile (precast, or cast-in-place), etc. exert a major influence on pile uplift. Moreover, the method used to calculate pile uplift in (2) is based on correlation relationships, and is therefore limited by the framework of experimental field investigations. It is impossible to extrapolate for short piles, which are most effective in agricultural construction. The author therefore proposes an original method for calculating pile uplift in swelling soils, which is based on differential equations of the theory of thermoelasticity. To determine pile uplift, let us examine the case when a pile cuts completely through a layer of swelling soil (see Fig. 1 ). For its incomplete penetration, the total uplift h o is the sum of the uplift h e of the soil layer beneath the end of the pile, and the uplift h due to frictional forces along its lateral surface. The latter are determined just as in the first case.

Effect of frost-heave forces of soils on the bearing capacity of pyramidal piles

1. Foundations formed from short pyramidal piles can be used in soils slightly prone to heaving without any restructions placed on bearing capacity, and should never be used in soils highly prone to heaving.

Two case studies of unsatisfactory performance of short bored piles : Sharma, D; Prakash, C; Chandra, R Proc 6th international conference on expansive soils, New Delhi, 1–4 December 1987P309–316. Publ Rotterdam: A A Balkema, 1988

Two case studies of unsatisfactory performance of short bored piles : Sharma, D; Prakash, C; Chandra, R Proc 6th international conference on expansive soils, New Delhi, 1–4 December 1987P309–316. Publ Rotterdam: A A Balkema, 1988

Behaviour of short bored piles in expansive soils during the stage of swelling : Bhandari, R K; Balodhi, G R; Chandra, R; Prakash, C Proc 6th international conference on expansive soils, New Delhi, 1–4 December 1987P295–300. Publ Rotterdam: A A Balkema, 1988

Behaviour of short bored piles in expansive soils during the stage of swelling : Bhandari, R K; Balodhi, G R; Chandra, R; Prakash, C Proc 6th international conference on expansive soils, New Delhi, 1–4 December 1987P295–300. Publ Rotterdam: A A Balkema, 1988

Load tests on short pile segments : Redel, C Proc eighth asian regional conference on soil mechanics and foundation engineering, Kyoto, 20–24 July 1987V1, P405–410. Publ Japan: Japanese Society for Soil Mechanics and Foundation Engineering, 1987

Load tests on short pile segments : Redel, C Proc eighth asian regional conference on soil mechanics and foundation engineering, Kyoto, 20–24 July 1987V1, P405–410. Publ Japan: Japanese Society for Soil Mechanics and Foundation Engineering, 1987

Design of short piles in expansive soils: a probabilistic approach : Ali, E M; Abbadi, S E M Proc ninth regional conference for Africa on soil mechanics and foundation engineering, Lagos, September 1987V1, P307–311. Publ Rotterdam: A A Balkema, 1987

Design of short piles in expansive soils: a probabilistic approach : Ali, E M; Abbadi, S E M Proc ninth regional conference for Africa on soil mechanics and foundation engineering, Lagos, September 1987V1, P307–311. Publ Rotterdam: A A Balkema, 1987

Superpile system: A feasible alternate foundation for tension leg platforms in deep water

Abstract This article discusses a possible alternate foundation system for a tension leg platform (TLP) in deep water. It was developed through Tecnomare S.p.A. for Agip S.p.A. during a feasibility study of a site located in the southern Adriatic Sea having a water depth of 827 m. The system is a combination of a pile‐gravity foundation, with relatively short (≍20 m) steel piles of very large diameter (6 to 12 m) called “superpiles,”; which are closed at the top and open at the bottom. The superpiles are installed in soft soil under the effect of self‐weight and active suction. Permanent tension of the TLP tendons is equilibrated by self‐weight only; tension due to wave action is equilibrated by the weight of the soil inside the superpiles. In fact, a pulsating tension applied to the superpiles generates a suction in the pore water that tends to keep the soil plug inside the cylinder and prevents the cylinder as a whole from being extracted from the (impervious) foundation soil. The results of analyses of the installation and in service behavior of superpiles are described on conventional principles of soil mechanics and related to a typical profile at the Adriatic site. Installation problems are briefly discussed; then the stability in service is examined to evaluate the capacity of superpiles in compression and tension and the associated factors of safety. Finally, considering the pore pressure gradient generated by the applied tension inside the soil plug, the flow rate and related deformations during storms and during the entire expected life of the TLP are evaluated. The proposed superpile system appears to be feasible, simple to install, and economical. Further study and experimental research are justified to optimize the system.

A technical note on the probabilistic analysis of short piles on expansive soil

Abstract Expansive soils pose major problems to construction in Sudan and many other countries all over the world. The short pile is one of the popular foundation types used in expansive soils. A probabilistic model for the short-pile-expansive-soil interaction problem is presented. The soil properties are represented by random variables and the probability of failure is estimated. A case study is given to illustrate the use of this model in practice.

The development of the sexually indifferent gonad in the prosimian, Galago crassicaudatus crassicaudatus.

The morphogenesis of the sexually indifferent gonad of the primate Galago crassicaudatus crassicaudatus was studied by high-resolution light microscopy and electron microscopy in 15 embryos aged 26 to 33 days. Onset of gonadal development follows the morphogenesis of the mesonephros by a conspicuous interval and is identified as the time when the first primordial germinal cells arrive in the region ventral to the central third of the mesonephros; this is followed by intense proliferation of the coelomic mesothelial cells lining the area. They become organized into short piles that deepen in the underlying mesenchyme, enclosing the germinal cells in the process. Rapidly, the piles become confluent forming a compact mass, the gonadal blastema, which is soon cleaved into gonadal cords by stroma and vascular lacunae. The mesonephros becomes involved in the morphogenesis of the gonad only in late stages of development when anatomic continuities become established between the capsules of its regressing glomeruli and the elongating gonadal rete cords. These observations show that in the Galago the somatic cells of the gonadal blastema, i.e., the precursors of the definitive testicular and ovarian sustentacular cells, derive from the coelomic mesothelium in contrast to other mammals, e.g., ruminants and rodents, where they are of mesonephric derivation. This important point is discussed in light of the differences that exist among species with regard to the structural complexity, functionality, and stages of differentiation/involution of their mesonephroi on the one hand, and the time of gonadal development on the other.

Bearing capacity of friction piles in marine clay

A full-scale investigation with two instrumented test piles was carried out at the St Alban test site, to study the increase in bearing capacity with time of short friction piles jacked into an over-consolidated soft sensitive marine clay. It is shown that the increase in shaft bearing capacity with time is significant and reaches about 12 times the initial shaft supporting capacity. The maximum skin friction is developed when the excess pore pressures generated during driving are fully dissipated after about 600 h. The results of load tests strongly suggest that effective stress parameters govern the behaviour of friction piles during the reconsolidation phase. The shaft bearing capacity is underestimated by approximately 45% with an effective stress approach in which the Ko, value is inferred from 1 – sin φ. However, if the measured values of Ko are taken, the calculated load carried by shaft friction is 70–90% of the actual shaft capacity. It is shown that the ultimate toe bearing capacity is strain rate dependent. For strain rates less than 5 × 10-4/s, which corresponds to pile penetration rates less than O·1 cm/s, the behaviour of tbe clay surrounding the toe is partially drained. Thus, the prediction of toe resistance for load testing conditions, i.e. a penetration rate of about 0·0001 cm/s, is complex and cannot be carried out with the undrained characteristics of the clay. Un essai en vraie grandeur a été effectué sur deux pieux instrumentés au centre d'expéiences de St Alban afin d'étudier I'accroissement dans le temps de la portance des pieux flottants courts vérinés dans une argile marine tendre surconsolidée sensible au remaniement. L'article démontre que la portance s'accroît de façon significative dans le temps et atteint environ 12 fois la valeur originale. Le frottement maximal est atteint lorsque les surpressions interstitielles créées au cours du battage des pieux se dissipent complètement après environ 600 h. Les résultats des essais de chargement montrent que les paramètres de contrainte effective régissent le comportement des pieux flottants pendant la phase de reconsolidation. La portance est sous-estimée d'environ 45% avec une méthode employant la contrainte effective dans laquelle la valeur Ko, est prise égale à 1 – sin ø. Cependant, si on prend les valeurs mesurées de Ko la charge calculée portée par le frottement représente entre 70% et 90% de la capacité réelle. On démontre que la force portance limite de pointe dépend dutaux de déformation. Pour des taux de déformation inférieurs à 5 × 10-4'/s, ce qui correspond à des vitesses de pénétration inférieures à 0, l cm/s, le comportement de l'argile entourant la base du pieu est partiellement drainé Il est ainsi très dificile de prédire la réistance de pointe pour des conditions d'essais de chargement, c'est-à-dire un taux de pénétration d'environ 0,001 cm/s, et aucune prédiction ne peut se faire sur la base des caractéristiques non-drainées de l'argile.

Ultimate lateral pile capacity in two-layer soil : University of Sdyney chool of Civil and Mining Engineering reportR503, Aug 1985, 25P

Expressions are derived for the ultimate lateral load capacity of a in a two-layer cohesive soil profile. Both free head and fixed head piles are considered, and, in each case, dimensionless solutions are given for failure of the supporting soil (short pile failure) and failure of the itself (long pile failure). Some parametric solutions are plotted, and an illustrative example is given to demonstrate the application of the analysis. (TRRL)

Uplift behaviour of short piles in uniform sand : Subba Rao, K S; Venkatesh, K H Soils FoundV25, N4, Dec 1985, P1–7

Uplift behaviour of short piles in uniform sand : Subba Rao, K S; Venkatesh, K H Soils FoundV25, N4, Dec 1985, P1–7

Uplift Behaviour of Short Piles In Uniform Sand

The results of laboratory studies on the uplift behaviour of short piles in uniform sands are presented. Smooth and rough mild steel piles (12.7 mm in diameter) in two uniform sands were used in the investigation. Tests were conducted for dry and submerged conditions of soil placed at either of the two densities (loose or dense). The uplift capacity was found to increase with L / D ratio, pile roughness, soil density and particle size. Pile movements of about 5% of pile diameter in loose sands and about 10% of pile diameter in dense sands were found to be necessary to mobilise the uplift capacity. These values are much more than 3 to 6% required for shaft loads during push-in tests. The unit skin frictions during pull-out tests are significantly less than during push-in tests, especially in case of rough piles for which it is as much as 80% less. Submergence resulted in reduction of uplift capacity in all cases, earth pressure coefficients, however, reduced only in case of piles in dense sand and remained almost unaffected for piles in loose sands.

Experimental Studies on Epizoochorous Dispersal in Californian Plants

Experiments studying degrees of adherence ability to various surfaces were undertaken with presumably epizoochorous diaspores of 14 native and eight introduced species from southern California. A commonly available laboratory shaker was modified so as to provide a standard means for dislodging diaspores from surfaces. Diaspores were dropped onto a cloth-covered board and percentages of dislodged diaspores recorded after inversion and then after intervals of shaking. Three fabrics were used: a velvet with short pile, an artificial wood with short curly strands, and a furlike fabric with straight strands. Attachment to the velvet was nil for most species, showing that a lower threshold for strand length necessary to promote attachment exists. On the artificial wool, some species tended toward brief attachment, some toward prolonged attachment, and some were intermediate. Results with the furlike fabric were similar, but a difference could be seen in that diaspores with hooklike devices adhered better to the artificial wool; a few species (notably grasses with bristly awns) showed better adherence on the furlike fabric. Diaspores were also tested on natural animal surfaces (one feather and four fur samples). Natural substrates proved comparable to artificial counterparts. Distinctive categories of diaspores are evident, based upon diaspore morphology and adherence capability. Nature of surface proves more important than weight or size of the diaspore in promoting adherence.

Analysis of ancient and medieval glasses by INAA

A scheme for instrumental neutron activation analysis of ancient and medieval glasses is proposed. The combination of three irradiations (short time, pile and epithermal) enables the determination of 34 elements. The accuracy of the method is evaluated by analyzing two glass standard reference materials. Results from the analysis of three glasses from different times are presented.

Linka i sezonowe zmiany sierści u jenota

An examination was made of the moult and seasonal pelage variations in adult and juvenile raccoon dogs, Nyctereutes procyonoides (Gray, 1834) from Eastern Finland. The Arctic fox (Alopex lagopus) served as a reference animal. Raccoon dog pelage is composed of four types of hair: guard hairs, long pile hairs, short pile hairs, and underfur. Whelps moult at the age of 4-5 weeks to a new summer pelage.

Regeneration of the cell wall of protoplasts of the fission yeastSchizosaccharomyces versatilis in liquid media and their reversion to cells

Regeneration of the cell wall and reversion of protoplasts with a completely regenerated cell wall to cells were studied by light and electron microscopy in protoplasts of the fission yeastsSchizosaccharomyces versatilis. On their surface the protoplasts regenerated a complete new wall even m liquid media The wall regeneration began with the formation of a thin irregular net of flat bundles of long microfibrils and the net was gradually filled with aggregates of short straight microfibrils and small piles of amorphous material. Osmotically resistant organisms with regenerated walls were detected after a 4–6 h cultivation Depending on the nutrient medium used 10–80 % of protoplasts with the regenerated wall were obtained that reverted subsequently to cells. The high percentage of the wall regeneration and reversion to cells was reached by combining cultivation in a poor medium with that in a rich medium Reversion to cells could only occur after the protoplasts had regenerated rigid cell walls These walled protoplasts underwent septation, and, by polar growth, produced cylindrical cells, further dividing by fission.