Effect of Relative Compaction on the Bearing Capacity of Cohesive Soils

Abstract One of the most popular types of foundations in layered subsoil with very differentiated soil shear strengths are precast piles. One of the reasons is the fact that we can well control the driving process during the installation of these piles. The principles of the assessment of bearing capacity and settlements of the piles given by Eurocode 7, concentrate on two main methods, i.e., Static Pile Load Tests (SPLT) and Dynamic Driving Analysis (PDA). However, the evaluation of real load-settlement curve for piles being driven in layered subsoil, where noncohesive and cohesive soils occur alternately, is neither easy nor straightforward. In the paper, the results of both SPLT and PDA tests for objects on the highways in Poland are presented. Field investigations carried out at various time points since the installation of piles (from 7 to 90 days) revealed an increase of bearing capacity with time. The reason for this may be a change of the soil state near the piles due to their driving (displacement of piles) as well as a change of microstructure at the contact between soil and pile shaft. The results of load tests were referred to the geotechnical parameters of the subsoil, which was recognized by means of traditional borings and CPTU tests. The results of tests allow phenomena occurring with time to be assessed and bearing capacity of precast piles to be predicted.

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A Review Study on Sand Compaction Piles in Cohesive Soils and as a Liquefaction Resistance Technique

10.46532/978-81-950008-1-4_078 ◽

2020 ◽

pp. 354-357

Author(s):

Aarthi N

Keyword(s):

Bearing Capacity ◽

State Of The Art ◽

Ground Improvement ◽

The State ◽

Cohesive Soils ◽

Liquefaction Resistance ◽

Detailed Review ◽

The Subject ◽

Review Study

The paper presents a detailed review of the state-of-the-art ground improvement technique namely sand compaction piles. The technique being originated in Japan has flourished around the globe for its efficient characteristics to act as a reinforcing member when it is installed in clays and is recognized as one of the best methods to prevent liquefaction. Known for its larger bandwidth of advantages, articles summarising the literature contribution on the technique are found to be very limited. Therefore, an attempt has been made to review the noteworthy literature that provides valuable information on the subject. An overview of the literature present on sand compaction piles installed in cohesive soils targeted to meet various demands like increasing bearing capacity, settlement, etc., and the technique’s efficiency in mitigating liquefaction associated problems are discussed.

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Capacité portante de pieux isolés dans les argiles sensibles: étude de cas par la méthode pénétrométrique

Canadian Geotechnical Journal ◽

10.1139/t89-052 ◽

1989 ◽

Vol 26 (3) ◽

pp. 375-384 ◽

Cited By ~ 1

Author(s):

Marius Roy ◽

Luc Tanguay

Keyword(s):

Bearing Capacity ◽

Key Words ◽

Cohesive Soils ◽

Friction Component ◽

Good Potential ◽

Capacité Portante ◽

Loading Tests ◽

Single Piles ◽

Lateral Friction

The penetrometer test has been used to determine the bearing capacity of driven and jacked-in single piles in sensitive clays. The cases presented in this paper were carried out on two sites with steel, concrete, and wooden piles. The bearing capacities calculated on the basis of the results of penetrometer tests show that this approach has a good potential and at the same time is simple and fast. It has been possible to obtain a calibration by a comparison with the loading tests carried out on each of the piles. Taking into account the low strength of some of our clays, experience has to be gained in order to adapt the lateral unit friction curves to our clays. This approach also has the advantage of allowing the determination of the bearing capacity of wooden piles and of taking into account the conical effect when determining the lateral friction component. Key words: penetrometer test, piles, bearing capacity, cohesive soils, point resistance, lateral friction, steel, concrete, wood. [Journal translation]

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A Consideration of Geosynthetic-Reinforcement on Bearing Capacity of Cohesive Soils

Proceedings of geosynthetics symposium ◽

10.5030/jcigsjournal1995.10.93 ◽

1995 ◽

Vol 10 ◽

pp. 93-101

Author(s):

Kunio MINEGISHI ◽

Katsuhiko MAKIUCHI

Keyword(s):

Bearing Capacity ◽

Cohesive Soils ◽

Geosynthetic Reinforcement

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Proposal for calculating the bearing capacity of screw displacement piles in non-cohesive soils based on CPT results

Studia Geotechnica et Mechanica ◽

10.2478/sgm041204 ◽

2012 ◽

Vol 34 (4) ◽

pp. 41-51 ◽

Cited By ~ 5

Author(s):

Adam Krasiński

Keyword(s):

Bearing Capacity ◽

Static Loading ◽

Load Transfer ◽

Transfer Functions ◽

Cohesive Soil ◽

Cohesive Soils ◽

Considerable Influence ◽

Calculation Methods ◽

Capacity Calculation ◽

Loading Tests

Abstract Screw displacement pile technology is relatively new and is still being developed. A specific characteristic of those piles is their very considerable influence on soil properties during the installation, which renders classical bearing capacity calculation methods insufficient. Some methods for calculating the bearing capacity of screw displacement piles have already been presented in literature, for example, by Bustmante and Gianesselli [2], [3], Van Impe [17], [18], Maertens and Huybrechts [15], Ne Smith [16] as well as Basu and Prezzi [1]. This paper proposes a new method of calculating the bearing capacity of screw displacement piles in non-cohesive soil which is based on CPT results. It has been devised as a result of research project No. N N506 432936 [11], carried out in 2009-2011. At 6 experimental sites screw displacement pile static loading tests were carried out together with CPTU tests of the subsoil. The results allowed us to establish soil resistances along the shaft ts as well as under the pile base qb and their correlations to the CPT soil cone resistances qc. Two approaches, both adapted to the general guidelines of Eurocode 7 (EC7) [20], were proposed: a classical approach and the second approach with load transfer functions application.

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Comparison of shallow foundation design using Eurocode 7 and Polish Standard

Journal of Water and Land Development ◽

10.2478/jwld-2014-0007 ◽

2014 ◽

Vol 20 (1) ◽

pp. 57-62 ◽

Cited By ~ 1

Author(s):

Andrzej Olchawa ◽

Andrzej Zawalski

Keyword(s):

Bearing Capacity ◽

Friction Angle ◽

Cohesive Soil ◽

Shallow Foundation ◽

Cohesive Soils ◽

Foundation Design ◽

Eurocode 7 ◽

Liquidity Index ◽

Undrained Conditions ◽

Factor Α

Abstract Bearing capacity of cohesive soils was calculated based on PN-B-03020:1981P and Eurocode 7. Strength parameters of cohesive soil modified by the authors: shear strength in undrained conditions cu, effective cohesion c' and effective friction angle φ' were adopted for calculations acc. to Eurocode 7. Values of these parameters depend on a leading parameter - liquidity index IL. Bearing capacity was calculated for two pad foundations of a size B × L = 2.0 × 3.0 m and 1.5 × 2.0 m and for one 2.0 × 14.0 m strip foundation. The capacity calculated acc. to EC 7 was reduced by multiplying by a factor α = 0.87 to account for different bearing capacity coefficients in Polish Norms and Eurocodes. Performed calculations showed comparable bearing capacity of substratum irrespective of adopted norms EC 7 and PN for foundation pads. In all analysed cases, however, the bearing capacity of foundation strips calculated acc. to Eurocode 7 was higher than those calculated acc. to PN-B-03020:1981P. The reason is in the values and ways of accounting partial security coefficients and in differences in the values of shape coefficients used in the equation for ultimate bearing resistance of soil substratum.

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