Fundamentals of Geotechnical Engineering

Principles of Foundation Engineering and Principles of Geotechnical Engineering were originally published with 1984 and 1985 copyrights, respectively. These texts were well received by instructors, students, and practitioners alike. Depending on the needs of the users, the texts were revised and are presently in their eighth editions. These texts have also been translated in several languages. Toward the latter part of 1998, there were several requests to prepare a single volume that was concise in nature but combined the essential components of Principles of Foundation Engineering and Principles of Geotechnical Engineering. In response to those requests, the first edition of Fundamentals of Geotechnical Engineering was published in 2000. This text includes the fundamental concepts of soil mechanics as well as foundation engineering, including bearing capacity and settlement of shallow foundations spread footings and mats), retaining walls, braced cuts, piles, and drilled shafts

Principles of Foundation Engineering

A must-have resource for all foundation engineering courses, Principles of Foundation Engineering, 9th Edition provides a careful balance between current research and practical field applications as it introduces civil engineering students to the core concepts and applications of foundation analysis design. Throughout this best-selling book, Dr. Das and Dr. Sivakugan emphasize how to develop the critical judgment civil engineers need to properly apply theories and analysis to the evaluation of soils and foundation design. This new edition includes three new chapters that highlight developing topics. This edition also provides a wealth of worked-out examples and multiple new figures that emphasize the skills most critical for students to master as successful civil engineers

Vertical Vibrations of Block Foundations

Steady state vertical vibration tests were conducted on test blocks measuring 1.5m x 0.75m x 0.7 m and 3m x 1.5m x 0.7m resting on ground surface. The amplitudes of vibration the blocks were measured at different frequencies. Dynamic shear modulus of the soil at site was also determined by conducting in-situ tests. The natural frequencies and amplitudes of vibration were calculated by (i) elastic half space method and (ii) impedance function method. A comparison was then made of the observed and the computed values natural frequencies and the vibration amplitudes. The data obtained shows that for this case the natural frequencies could be reasonably predicted by either of these methods. The observed and computed amplitude however showed a wide scatter. Further details are given in the paper

Dynamic Response of Block Foundations

This paper presents the results of comparison of the computed and observed response of two block foundations made of concrete. The test blocks measuring 3.0m x 1.5m x 0.7m and 1.5m x 0.75m x 0.70m were cast on level ground. The blocks were excited into vertical vibrations using a speed controlled mechanical oscillator. The amplitudes of vibration at different frequencies of excitation were measured in each case using acceleration transducers mounted on appropriate faces of the block. Dynamic shear modulus at this site was also determined b¥ conducting in-situ tests namely the wave propagation test, the cyclic plate load test, and the standard penetration tests. From this data the dynamic shear modulus versus shear strain plot was obtained. The natural frequencies and the vibration amplitudes of the test blocks were then calculated by (i) the linear spring method, (ii) the elastic half space method. A comparison was then made of the observed and computed natural frequencies and the vibration amplitudes of the blocks. The results of this comparison showed that for the cases of vertical vibrations, the natural frequencies in this case could be reasonably predicted by either of the methods used. The calculated and observed amplitudes, however, showed a wide variation. The details of tests performed and the analysis are discussed in this paper

Cyclic Load-Induced Settlement of Foundations on Clay

Laboratory model test results for estimating the permanent settlement of a surface strip foundation supported by a saturated clay are presented. The tests were conducted with one model foundation and one clay soil. The model foundation was subjected to an initial static load, and then a cyclic load was superimposed on it. The magnitude of the static load intensity and the amplitude of the intensity of cyclic load were varied. Based on the model test results, relationships for the permanent foundation settlement and intensities of the static and cyclic load are presented

A Case History of Site Instability Due to the Presence of a Shale Layer Above Sloping Bedrock

A study conducted for St. Louis County of Missouri, United States of America classified several areas of the county as unstable for any type of construction because of the presence of high plastic shaley clay or clayey shale on sloping bedrock. These areas are considered to have a potential for site instability to occur due to any change in natural conditions that may increase the moisture content of the high plastic shaley clay or clayey shale. A two-story parking garage, founded on shallow foundations, constructed in one of the potentially unstable zones, showed some movement after several years of its construction. After movements in the structure were observed, further review of the subsurface conditions revealed that as a result of construction at the site, the clayey shale layer became exposed, thus, creating easy access for water to enter this layer. Infiltration of water caused softening of the clayey shale layer, which in turn caused movements in the structures constructed on the site. This paper presents the detailed information about the subsurface conditions and type of structures constructed on the site

Cyclic Load Resistance of Vertically Reinforced Sand Subgrades

This paper presents the results of laboratory scale model footing tests which were conducted for determining the cyclic load resistance of sand subgrades reinforced with semi-flexible vertical elements. The tests were conducted in a sandbox having a length of 91.5 cm, width 15.25 cm, and height of 61.0 cm. Steel bars 1. 58 mm in diameter were used as reinforcing elements. Tests were also conducted by using rough reinforcing elements. The test results indicate that the value of coefficient of elastic uniform compression of the footing on sand increases with the provision of vertical reinforcement in the sand subgrade. Rough Reinforcing elements were found to be more effective in improving the value of Cu as compared to plain reinforcing elements. The improvement in the value of Cu as a result of provision of vertical reinforcement was observed to depend on initial relative density of sand and, also on parameters such as the length, extent and spacing of reinforcing elements

Lefkoşa surlariçi zeminlerinin özellikleri

Alluvial soils and overconsolidated clays constitute the most soils of Cyprus. The alluviums show relatively high apparent strength in their dry state. However, with saturation their strength decreases. The clayey parts of the alluviums have low to medium swelling potential. Overconsolidated swelling clays of Cyprus occurred as a result of the alteration of the Troodos ophiolite and the pelagic sedimentary cycles that followed in the post Createceous period. The calcium corbonate content of the clays (marls) originated from the limestones and dolomites of the Kyrenia zone. There is widespread damage to the buildings, major roads and highways all over the country which were founded on swelling clays. Clays of Cyprus can be divided into five groups. 1.Clays of Mamonia Complex, 2.Bentonitic Clays, 3.Clays of Kythrea Group, 4.Mesaoria clay zone and 5.Alluvial clays. Large parts of Nicosia is covered by man made fills, alluvial soils and swelling clays  Swelling clay problems occur continuously every year due to the soil expanding in the winter and shrinking in the summer. Nicosia is almost flat lying at about 110 - 160m above the mean sea level and is located between the Kyrenia and Troodos ranges. Several streams are flowing from south and north. The soils of Nicosia are; Man made fills, Alluviums, Mesaria Clay Zone, Kalavasos Formation and Kythrea Group. The Kythrea group is widespread in the north of Nicosia. Alternation of sandstone-siltstone-marl-claystone are widespread within the group. The group is only observed in the Turkish Republic of Northern Cyprus and its overconsolidated clays exhibits low to high swelling potential. Mesaria Clay Zone is widespread in the south of Nicosia and consists of gravel-sand-claystones. Overconsolidated Nicosia clays exhibits low to very high swelling potential. Nicosia is covered by extensive alluvial deposits of up to a thickness of 22 m. SPT, UD, and core samples taken from the boreholes are tested in the laboratory for mechanical (grading) analysis, moisture content, unit weight, specific gravity, Atterberg limits, and CaCO3 content. X-ray diffraction (XRD), Scanning Electron microprobe (SEM) and Energy Dispersive X -Ray (EDX) analysis are also conducted. The properties of Nicosia walled city soils are determined by boreholes drilled in five different locations between 2001 and 2007. The soils are man made fills, alluviums, Nicosia clays, Kalavasos Formation and Kythrea group. Man made fills and alluviums are present from the surface to between 7.20 m and 22.00 m depth. The water table is between 4.90 m and 10.00 m. There is no swelling and shrinkage within the walled city. The highest liquid limit (LL) values of the analyzed samples are present in yellowish to light grey weathered, oxidized Nicosia clay (marl). Clay and montmorillonite contests are increasing within these samples. CaCO3 contents are higher in the light coloured samples. The Liquid limit (LL) values are decreasing with the increasing amount of CaCO3. The lowest SPT N values are present in the fine grained alluvium deposits. The SPT N values of Nicosia clays ( marls) are between 33 and 75. The semi quantitative X-ray diffraction (XRD), Scanning Electron microprobe (SEM) and Energy Dispersive X -Ray (EDX) analyses indicated that the predominant clay mineral is montmorillonite (smectite), illite and chlorite or kaolinite are the other abundant clay minerals. Calcite is the major mineral of the clays (marls), quartz and feldspar are also present at high amounts. Montmorillonite (smectite) with an amount ranging between 10 and 30%. illite and chlorite or kaolinite with an amount ranging between 5 and 10%. Calcite with an amount ranging between 30 and 65% is the major mineral of the alluviums and Nicosia clays (marls). The other minerals are quartz ranging between 2 and 6%, feldspar ranging between 4 and 15 %, and dolomite ranging between 2 and 9%. EDX analysis for the Nicosia clays indicated that Si, Al, K and Mg peaks are together. Therefore predominant clay minerals are montmorillonite (smectite) and illite. The high amount of Fe %10 it could be the result of the ofiolitic Fe minerals. Despite the overconsolidation character the soils have high porosity. Keywords: Atterberg limits, montmorillonite, calcium carbonate, Nicosia clays. Kıbrıs zeminlerinin büyük bir bölümünü şişen killer, alüvyonlar ve evaporitik kayaçlar oluşturur. Kuzey KıbrısTürk Cumhuriyeti hemen hemen tamamıyle killi formasyonlar ve alüvyonlar ile kaplıdır. Kıbrıs killeri Trodos ofiyolitinin ayrışması ve Kretase sonrası pelajik tortul olarak oluşmuşlardır. Kuzey Kıbrıs (Girne) zonundaki kireçtaşı ve dolomitler ile Güney Kıbrıs zonundaki tebeşirlerin killerin oluşumunda kaynak olması ve biojenik oluşum, killi formasyonların yüksek oranda montmorillonit (smektit) ve kalsium karbonat içermelerini sağlamıştır. Mesarya zonu ve Değirmenlik grubunda bulunan aşırı konsolide killi zeminlerin kurak yarı-kurak akdeniz iklimine bağlı olarak su içeriğinin artması ile şişmesi ve azalması ile büzülmesi sonucu yapılarda hasarlar oluşmaktadır.  Düşük taşıma kapasiteli alüvyonlar çok yaygın olarak Mesarya ovasında, Lefkoşa, GaziMağusa ile doğu ve batı kıyılarda gözlenir. Alüvyonlar üzerine inşa edilen tarihi yapılarda oturmalardan veya göçmelerden büyük hasarlara rastlanmaktadır. Son on yıl içerisinde yapılarda meydana gelen hasarları önlemek ve tarihi binaların restorasyonu için Kuzey ve Güney Lefkoşa’da geoteknik incelemeler yapılmıştır. UD, SPT ve karot sondaj örnekleri alınarak laboratuvarda elek analizleri, doğal su içeriği, birim ağırlık, özgül ağırlık, Atterberg limitleri ve kalsiyum karbonat (CaCO3) miktarlarının belirlenmesi için deneyler yapılmıştır. Elektron mikroskop (SEM), yarı kantitatif (XRD) ve yarı kantitatif (EDX) element analizleri de yapılmıştır. Elde edilen değerler ışığında Lefkoşa surlariçi zeminlerinin dolgu, alüvyon, Lefkoşa killeri, Mermertepe formasyonu ve Değirmenlik grubundan oluştuğu belirlenmiştir. Dolgu ve alüvyon zeminlerin 7.20 m ile 22.00 m arasında olduğu su seviyesinin 4.90 m ile 10.00 m arasında olduğu ve su seviyesinin Lefkoşa killeri üzerinde olduğundan şişme ve büzelme meydana gelmediği tesbit edilmiştir. Lefkoşa surlariçi zeminlerinin özellikleri sunulmaktadır. Anahtar Kelimeler: Atterberg limitleri, montmorillonit, kalsiyum karbonat, Lefkoşa killeri

Dynamic Loading Induced Settlement of Strip Foundation on Geogrid-Reinforced Clay

Laboratory model tests to determine the load. The variation of the maximum permanent supported by geogrid-reinforced saturated clay and subjected to a low-frequency cyclic load are presented. In conducting the test, the foundation was initially subjected to an allowable static load. The cyclic load was then super-imposed over the static permanent settlement of a surface strip foundation settlement with the intensity of the static load and the intensity of the amplitude of the cyclic load are also presented

Análisis comparativo en losas de cimentación: losas aligeradas mediante bloques de EPS frente a losas macizas

The objective of this article is to confirm the different behavior of the traditional slab foundation against a lightened, making a comparative analysis, using the MEF, of the first solution with a lightened slab using expanded polystyrene (EPS) blocks, joining solid areas on pillars with grating beams. Therefore there are two top and bottom plates covering the EPS blocks. The results obtained allow assert ourselves that in situations of soft soils, with possible problems of settlements, the proposed solution has significant advantages by reducing them a percentage will vary depending on specific conditions. Besides this, it reduces significantly the differential settlements between supports, so this alternative has a more uniform behavior, as well as constructive advantages.<br><br>El objetivo del presente artículo es confirmar el distinto comportamiento que presenta la solución tradicional de losa maciza frente a una aligerada, haciendo un análisis comparativo, aplicando el M.E.F., de la primera solución con una losa aligerada empleando bloques de poliestireno expandido (EPS) como material aligerante, uniéndose las zonas macizas bajo pilares mediante nervios. Se mantienen, por tanto, dos placas superior e inferior alrededor de los bloques aligerantes de EPS. Los resultados obtenidos nos permiten afirmar que en situaciones de suelos blandos, con posibles problemas de asientos, la solución planteada presenta importantes ventajas, al disminuir éstos en un porcentaje que variará en función de las condiciones particulares. Además de esto, se reducen en gran medida los asientos diferenciales entre apoyos, por lo que la alternativa planteada presenta un comportamiento más uniforme, así como ventajas constructivas