Soft Alluvium Research Articles

Scattering of plane harmonic P, SV, and Rayleigh waves by dipping layers of arbitrary shape

Diffraction of plane harmonic P, SV , and Rayleigh waves by dipping layers of arbitrary shape is investigated by using an indirect boundary integral equation approach. The layers are of finite length perfectly bonded together. The material of the layers is assumed to be homogeneous, weakly anelastic, and isotropic. The displacement field is evaluated throughout the elastic medium so that the continuity of the displacement and the traction fields along the interfaces between the layers is satisfied in a least-squares sense. Presented numerical results show that the surface strong ground motion amplification effects depend upon a number of parameters present in the problem, such as, type, frequency, and angle of the incident wave, the impedance contrast between the layers, the component of the displacement field being observed, and the location of the observation point at the surface of the half-space. The results demonstrate that the presence of soft alluvial deposits in form of dipping layers may cause locally very large amplification or reduction of the surface ground motion when compared with corresponding free-field motion.

Cracking of a PFA embankment over soft alluvium : Arber, N R Proc Symposium, on Failures in Earthworks, London, 6–7 March 1985P127–140. Publ. London: Thomas Telford, 1985

Cracking of a PFA embankment over soft alluvium : Arber, N R Proc Symposium, on Failures in Earthworks, London, 6–7 March 1985P127–140. Publ. London: Thomas Telford, 1985

Geological and geotechnical considerations on sections of the M25 : Newman, R L Highways TranspV31, N7, July 1984, P18–32

The author summarises papers presented by a number of authors at a January 1984 meeting of the Institution of Highways and Transportation held in London. The history of the planning concepts involved in the evolution of the London orbital road is outlined. A resume is given of the geology of the route from the terrace gravels and soft alluvium near Staines, through chalk with glacial cap, boulder clay, reading beds, chalk and clay with flints over. Problems and considerations associated with the earthworks and the selection of plant used at the construction of three large interchanges are discussed. An account was given of the most intensive structural section containing entrained and open cuttings, a cut and cover tunnel and an approach embankment between reinforced earth walls. The Thames Valley stage crossing a number of water filled gravel pits and disused pits is described, and an account is given of the intensive site investigation of the properties of the gault clay in Kent. Some aspects of research design and construction on the route described include the bell common tunnel. (TRRL)

Geotechnical aspects of Greenodd by-pass

Summary This paper describes the geotechnical aspects of the site investigation and construction of a by-pass to Greenodd Village in the southern part of the Lake District. The proposed route ran along west bank of the River Leven, crossed the main channel of the river and rejoined the existing road south of Greenodd. The investigation revealed that in places deep deposits of soft alluvium existed. Using the field measurements of permeability to determine the rate of consolidation in preference to values measured in the laboratory oedometer tests, it was decided that an embankment could be constructed safely and within a reasonable time. During construction the increase in excess pore pressure was monitored and the rate of filling modified to ensure a minimum factor of safety was achieved. The project also involved construction of two bridges. From the findings of the site investigation it was decided to adopt pile foundations with the piles being driven steel H piles having an enlarged section set back from the toe. This ensured that the pile reached the required driving set after only a short penetration into the gravel stratum underlying the soft alluvium. Pile tests were carried out on preliminary piles to confirm the adequacy of the design and on works piles to ensure the required load carrying capacity was actually achieved.

Two road embankments on soft alluvium : Cole, K W; Garrett, C Proc 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm, 15–19 June 1981, V1, P87–94. Publ Rotterdam: A. A. Balkema, 1981

Two road embankments on soft alluvium : Cole, K W; Garrett, C Proc 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm, 15–19 June 1981, V1, P87–94. Publ Rotterdam: A. A. Balkema, 1981

A comparison between the performance of two types of vertical drain beneath a trial embankment in Belfast

A link road is being constructed in Belfast to join the existing Ml and M2 motorways: one section of the road crosses extensive areas of soft alluvium on embankments rising to a height of 8 m above the existing ground level. A site investigation was carried out to determine the strength and consolidation properties of these soft soils. The values of the coefficient of consolidation were such that to construct the embankments in the time available and to ensure the settlements subsequent to the road opening are acceptable some form of ground improvement would be necessary. Vertical drains were considered to be the most appropriate solution to the problem. A site trial was carried out in which two types of vertical drain were installed beneath trial embankments and the drainage characteristics of the soil monitored. The results have shown good agreement between the laboratory and field data. Une route de jonction, destinée à relier les autoroutes existantes Ml et M2, est en voie de construction à Belfast; un tronçon de la route sur des remblais s'élevant à une hauteur de huit mètres au dessus du niveau du sol existant traverse de vastes zones d'alluvions mous. Une exploration in situ a été effectuée afin de déterminer la résistance et les propriétés de consolidation de ces sols compressibles. Les valeurs du coefficient de consolidation étaient telles qu'il fallait prévoir un système d'amélioration du sol pour permettre la construction des remblais dans les délais disponibles et pour assurer les tassements ultérieurs à l'ouverture de la route. On a considéré que les drains verticaux représentaient la solution optimale du problème. Un essai in situ a été effectué: deux types de drain vertical ont été installés sous le remblai d'essai et les caractéristiques de drainage du sol ont été observées. Les résultats démontrent une bonne corrélation entre les données de laboratoire et les données in situ.

Behaviour of a trial bank constructed to failure on soft alluvium of the river thames : Marsland, A; Powell, J J M Proc International Symposium on Geotechnical Aspects of Soft Clays, Bangkok, 5–6 July 1977, P505–525. Publ Bangkok: Asian Institute of Technology, 1977

Behaviour of a trial bank constructed to failure on soft alluvium of the river thames : Marsland, A; Powell, J J M Proc International Symposium on Geotechnical Aspects of Soft Clays, Bangkok, 5–6 July 1977, P505–525. Publ Bangkok: Asian Institute of Technology, 1977

Wick drains employed on malton by-pass : Beyer, M G; Falconer, J S Ground Engng, V11, N1, Jan 1978, P16–18

The purpose of this new type of vertical drainage system is to accelerate the process of consolidation of soft alluvial deposits under embankment loading. An economical method of accelerating the consolidation process is achieved by shortening the distance between the drainage paths by means of highly permeable vertical drains inserted into the ground. The wick drain is a high quality special non-woven polyester fabric which is resistant to all acids and basic chemicals in soils, to bacteria, frost, and UV radiation. Its pore volume in excess of 80% accounts for the drain's high water transmissibility. The wick drain is 300 mm wide and 4 mm thick and is supplied in roles of up to 300 m in length. The route of the bypass crosses a flood plain before rejoining the original truck road. Problems were anticipated with settlement and stability of the embankments. Because of potential flooding, the embankment was formed above the flooding level with rock fill arising from the cutting. To reduce the drainage path within the aluvium and accelerate the consolidation settlement and increase shear strength, vertical drains were installed to an average depth of 5 m below ground level. A specially designed tubular steel lance was vibrated into the ground through which the wick drain was passed through and into the ground. The drain was then cut off approximately 0.5 m above ground level. Instrumentation was provided to monitor the construction of the embankments as well as both the drained and undrained areas of the special embankment.

Embankments on soft alluvium. Settlement and stability study at Durban

Embankments on soft alluvium. Settlement and stability study at Durban

Performance of an embankment supported by stone columns in soft ground

To investigate the effectiveness of stone columns in reducing the settlement of high embankments built on soft alluvium, stone columns were constructed under one end of the East Brent trial embankment using the vibro-flotation replacement technique. Here the alluvium was 27·5 m thick, the columns were O·9 m in diameter and 11·3 m long, and they were constructed on a triangular grid at 2·4 m centres. The embankment was built to a height of 7·9 m. The foundations were instrumented, and a comparison of the piled and unpiled ground shows that the columns hadno apparent effect on the performance of the embankment. Some of the construction problems are commented on, and the performance records andpossible reasons for the inefiectiveness of the columns are presented in the Paper. Ajin d'enqut?ter sur l'eficacité de colonnes en Pierre dont l'objet est de réduire le tassement de hauts remblais posés sur un dépôt alluvionnaire mou, de telles colonnes ont ét éconstruites audessous d'une extrémitédu remblai d'essai de East Brent en utilisant la technique de remplacement par vibro-flottation. Dans ce casparticulier le dépôt alluvionnaire avait une épaisseur de 27·5 m: chaque colonne ayant O·9 m de diamétre et 11·3 m de longueur. Elles furent disposées selon une maille triangulaire à 2·4 m des centres. On a construit le remblai à une hauteur de 7·9 m. Les fondations ont été pourvues d'appareils de mesure et on a constate’ en comparant le terrain sur pieux et celui sans pieux, que les colonnes n'ont aucun effet prononcé sur la performance du remblai. Plusieurs problémes de construction sont discutés dans le document ainsi que les détails de performance et les diverses raisons auxquelles on peut attribuer l'ineficacité des colonnes.

Hotel Pegaso - Georgetown - Guayana Británica

The hotel is made up of a basement and a nine-storey high circular tower. In the first, the common use premises have been arranged, whereas the tower contains the bed-rooms and private apartments. A central service nucleus houses: staircases, lifts and vertical air conditioning ducts. It is built of a metal structure and concrete slabs for the floors. The partition walls dividing the bedrooms in the tower are arranged radially. For the foundations, box-type piles were used, filled with concrete, due to the soft alluvium soil on which the town stands.

Effects of the earthquakes of May 1960 in Concepción and vicinity

ABSTRACT The rocks and sediments of the region have been divided into four units: metamorphic rocks of unknown but great age; granites of Jurassic-Cretaceous age; fossiliferous sediments of Cretaceous and Tertiary age; Quaternary sands, silts, clays, gravels, and artificial fill. The metamorphic and intrusive rocks are deeply weathered. In general, damage is clearly related to the type of materials of construction, independently of the subsoil. Nonetheless, damage was over soft alluvium and artificial fill. The overpass on the north of the railway bridge on Rio Bio Bio sunk into artificial fill and was damaged. The houses that survived best were built of reinforced concrete or wood. Houses of adobe or bricks held together with poor mortar or mud failed miserably. In the steeper zones, danger from landslides menaces populous areas in the hills La Pólvora, Chepe, Chacabuco, and others.

DESIGN OF TAKASHIMA PIER NO. 3 ON THE SOFT FOUNDATION

This paper contains the design procedure of the Takashima Pier No. 3, a large scale pier on the deep soft alluvium, depth of ten meters below L. W. L., the surcharge of 3.0t/m2, and also designed so as to resist for seismic forces. The pier had been to be constructed on the soft clay strata of more than thirty meters thick. The magnitude of the cohesion assumed in this design of the foundation decided by the following methods, namely, the performance of unconfined compression tests of undisturbed samples, results of loading tests of piles at the construction site and the analysis of the existing structures near the construction site. The depth and inclination of the hard pan under the soft clay strata were found by the results of boring, pile driving and seismic prospecting. Following to the results of these studies, framed caissons on the friction piles were adapted as the main structure of the pier.