İstanbul neojen kilinin şişme davranışına ön konsolidasyonunun minerolojik özelliklerinin ve çevresel faktörlerin etkisi
Başlık çevirisi mevcut değil.
- Tez No: 39437
- Danışmanlar: PROF.DR. REMZİ ÜLKER
- Tez Türü: Doktora
- Konular: İnşaat Mühendisliği, Civil Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1993
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 154
Özet
Genellikle kurak ve yarıkurak iklimlere sahip bölgelerde yer alan, suya doygun olmayan killi zeminlerde arıtan su muhtevası ile,“ şişme ”adı verilen önemli hacim değişiklikleri meydana gelmektedir. Bu tür zeminlerle ilıgili mühendislik uygulamalarında şişme potansiyelinin, şişme basıncının önceden belirlenmesi ve bunlara etkiyen hem minerolojik hem de çevresel faktörlerin birlikte inıcelenmesi gerekmektedir. Böylece gereken önlemlerin alınıması, uygun temel sisteminin seçilmesi ve meydana gelebiılecek hasarların minimuma indirilmesi mümkün olmaktadır. Yapılan çalışmaların çoğunda, sadece eksenel yöndeki şişıme davranışları dikkate alınmış, bunlara etkiyen çevresel ve minerolojik faktörler birlikte düşünülmemiştir. Bu çalışmada, istanbul'un Güngören Formasyonu deniılen Neojen kilinin şişme davranışları ve bunlara etkiyen faktörler araştırılmıştır. Ayrıca Ankara-Kızılcahamam mevkiinden getirilen yine yüksek plastisiteli, şişme Özelliği gösteren kil numuneleri de kullanılmıştır. Numuınelerin X-Ray, DTA, SEM incelemeleri yapılmıştır. Hakim kil mineralleri belirlenmiş, mikroskop çekimlerinden ön yükün etkisi gözlenmiştir. ödometre deneyinde sabit hacim ve serbest şişme koışulları altında şişme basınçları ve miktarları belirlenımiş, ön yükün etkisini görmek amacı ile numuneler 1000 kPa'a kadar kademeli olarak yüklenip boşaltılmıştır. Deıney sonucunda elde edilen eğrilerden hacimsal sıkışma moıdülü (Mo) değerlerinin II.kademede. I.sinden daha büyük olduğu gözlenmiştir. Aynı deneyler başlangıç su muhtevası düşürülen, optimum su muhtevasında sıkıştırılarak hazırılanan numuneler üzerinde tekrarlanmıştır. Böylece başlanıgıç su muhtevasının ve kuru birim hacim ağırlığının şişme davranışı üzerindeki etkileri gözlenmiştir.. Söz konusu deneyler, ön yükün etkisini araştırmak için su ile karışıtırılıp, kendi ağırlığı altında çökeltilerek hazırlanan numuneler üzerinde de yapılmıştır. Numunelerin yanal yöndeki şişme davranışlarını beılirlemek amacı ile, modifiye edilmiş üç eksenli deney sistemi kullanılmıştır. Bu sistem ile numunelerin sükuınetteki toprak basıncı katsayıları (K0), izotropik ve anizotropik gerilmeler altındaki yanal şişme davranışları farklı efektif gerilmeler için belirlenmiş ve aralarında amprik bağıntılar geliştirilmiş, elde edilen sonuçlar karşılaştırılmıştır. Efektif gerilme arttıkça, şişme baısıncının azaldığı gözlenmiş, yanal şişme miktarları çap değişimi cinsinden ifade edilmiştir. Yanal şişme davranıışının ihmal edilemeyecek boyutlarda olduğu belirlenmişıtir.
Özet (Çeviri)
In general clayey soils in arid and semi-arid climates may undergo large volume changes with increasing water content. The mechanics of this phenomena known as swelling has been under intensive investigation during recent years.,. Intrinsic expansiveness of a soil is a property resulting from its mineral composition and grading and its interaction with water. It is a measure of the change in water content caused by or giving cause to a change in suction. Swell of an intrinsically expansive soil may be described as the volume change that resutls from a change in moisture content of suction. It can also occur in all soils due to a reduction in effective stress, or in some soils due to chemical changes. In expansive soil engineering the case of complete saturation is rarely of importance in practical problems. In the partially saturated state the relationship between moisture change and soil volume change will be affected by factors such as the structure of the soil and hysteresis in the moisture content suction relationship. In engineering usage it is more relevant to relate swell to change in suction. Swell due to a unit change in suction and swell due to a unit change in applied stress may not be of equal magnitude, except in the saturated state. Heave is the vertical displacement of a point in a soil mass or of a foundation that results from swelling of an intrinsically expansive soil. Swelling potential is in percentage of swell of a laterally confined sample on soaking under a 1 psi (7 kPa) surcharge, after being compacted to maximum density at optimum water content in the stardard AASHO compaction test. The main factors involved in the heave phenomene are; :;vi- Soil type (including the proportion of clay and its mineralogy. Especially, montmorillonite, the most significant expansive clay mineral that do not exist in unweathered igneous rocks. - Structure (flocculated particles tend to swell more than dispersed particle; cemented particles tend to reduce swell; fabrics that slake readily may promote swell). - Dry density (larger dry densities cause closer particle spacings and larger swells. - Moisture content (related to the suction for a given soil). - Permeability (time to heave is a function of permeability). Fissures can signif acantly increase permeability and promote faster rates of swell. - Thickness and depth of the expansive soil stratum. Insitu stress conditions (both vertical and horizontal ). - Externally applied loads. - Groundwater (fluctuating and shallow water tables provide a source of moisture for heave). - Climate (arid climates promote desiccation, while humid climates promote wet soil profiles). - Drainage (poor surface drainage leads to moisture accumulations or ponding). Composition of pore fluid (prevalence of monovalent cations increase shrink-swell ; divalent and trivalent cations inhibit shrink-swell). - Vegetative cover (trees, shrubs and grasses are conducive to moisture depletion by transpiration; moisture tends to accumulate beneath areas denuded of vegetation). Concentration of pore fluid salts (high concentrations of cations in the pore fluid tend to affect the magnitude of volume change; swell from osmosis can be significant over long periods of time). The minerological composition of expansive soils has an important bearing on the swelling potential. The five techniques which may be used are as follows x XVII- X-Ray diffraction - Differantial thermal analysis Dye adsorption - Chemical analysis and Electron microscope resolution. The techniques available for the prediction of anticipated volume change fall into three groups, namely, swell oedometer tests, soil suction methods and empirical techniques. Among these methods, oedemeter technique is the oldest an most commonly used method. Recently. American Society for Testing Materials (ASTM) standardized the swell oedemeter test procedures under the designation. This standard decribes three alternate oedemetre testing procedures, namely, free swell overburden tests to evaluate the anticipated volume changes. Overconsolidated clayey soils which with swelling potential spreaded out all over the world as well as Turkey. It is primarly important to define swelling pressure and total percentage of swell for engineering applications built on these soils. Without conducting sufficient investigations at highway and airport pavements, tunnel linings, irrigation channels, retaining walls excessive dameges can take place. It is possible to minimize the effects of swelling by conducting appropriate tests to determine swelling potential, to take the necessary precautions and by designing a suitable foundation systems. Heave problems account for more economic loss than all other soil problems. In this investigation, overconsolidated clayey soil samples which show swelling characteristics from Neogene around Istanbul have been tested. Furthermore, obtained swelling clay sample with high plasticity getting from Ankara-Kızılcahamam area has been used to make a compare with the results from other tests. Soil types (percentage and mineralogical composition of clay) and pre-loaded conditions which are the main factors affect swelling pressure and total percantage of swelling were investigated and relationship between those factors and swelling characteristics were also tested. Minerological structure of soil samples are determined by X-Ray, Scanning Electron Microscope, Differantial Thermal Analysis. XVIIISwelling pressure and total percentage of swelling were determined by oedemeter test under constant volume and unrestricted swelling conditions. In this system, the samples are loaded to 1000 kPa and then reduced gradually as it reaches surcharge pressure in order to observe affects of pre-loading. The same tests are also repeated by decreasing initial water content and compacting optimum water content. In this way the affects of dry-density and initial water content on the swelling behaviour are observed. Besides, all tests are applied on suspansion sample prepared from slurry in laboratory to analyse pre-load affecting. A modified triaxial testing system has been used in identifying lateral swelling behaviour. First, the total swelling values have been determined under the isotropic stress while the top of clay sample is open to drainage. The following series of experiments, applying constant confined stress to the cell, to create different effective stress, back pressure has been applied. Under the application of stress conditions on the cell, lateral swelling pressure of samples have been registered by pressure transducer depending on time, periodically, ultimate swelling pressure values have to be taken, again under isotropic stress. Lateral swelling quantities have been evaulated by closed burette system which is directly connected to the cell. The coefficient of Ko has been evaluated. The second cell which moves in vertical direction helps to create balancing pressure, and additional pressure on the loading shaft. The series of experiments which have taken place under isotropic stress, have been repeated for anisotropic stress. The results have been interpretated in accordance with the purpose of this study. The modified triaxial test system has been used on these clay samples and following results have been obtained: Swelling quantity of soil samples which are prevent axial swelling occured under different effective stress. When effective stress increase, quantity of lateral swelling decrease. And there is an opposite nonlinear relation between both of them. XIXBack pressures creating different effective stresses are applied to the soil samples in which anisotropic stress have been occured. Under this stress conditions, there is an opposite nonlinear relation between lateral swelling pressure and effective stress has been obtained. It is obtained that the ultimate swelling pressures under anisotropic stress conditions are smaller than those of isotropic ones.
Benzer Tezler
- Marmara akarsu havzasının Sarımeşe sırtları ile Marmara Ereğlisi arasındaki kesiminin jeomorfolojisi
Başlık çevirisi yok
HÜSEYİN ABDİOĞLU
- Domaniç (Kütahya) neojen havzasının sedimentolojisi ve kömür potansiyeli
Sedimentology and coal potential of the Domaniç (Kütahya) neogene basin
YAKUP ÇELİK
Doktora
Türkçe
1999
Jeoloji Mühendisliğiİstanbul ÜniversitesiJeoloji Mühendisliği Ana Bilim Dalı
PROF. DR. İ. ERDAL KEREY
- Demirci (Manisa) bölgesindeki piroklastiklerle ilişkili zeolit oluşumunun incelenmesi
Investigation of zeolite formation associated with pyroclastics in the demirci (Manisa) region
NİMET COŞKUN
Yüksek Lisans
Türkçe
2024
Jeoloji Mühendisliğiİstanbul Teknik ÜniversitesiJeoloji Mühendisliği Ana Bilim Dalı
PROF. DR. RECEP FAHRİ ESENLİ
DR. ÖĞR. ÜYESİ BALA EKİNCİ ŞANS
- Turgutlu (Manisa) neojen oluşuklarının tuğla-kiremit hammaddesi yönünden minerolojik petrografik ve jeokimyasal incelenmesi
Mineralogical petrographical and geochemical investigation of Turgutlu (Manisa) neogene formations for the tile and brick raw material
GÜRSEL YANIK
Doktora
Türkçe
2005
Jeoloji Mühendisliğiİstanbul Teknik ÜniversitesiJeoloji Mühendisliği Ana Bilim Dalı
PROF. DR. BEKTAŞ UZ
DOÇ. DR. FAHRİ ESENLİ
- Gördes çevresindeki neojen serilerin ve zeolitleşmenin jeolojik mineralojik ve jeokimyasal incelenmesi
The Geologic mineralogic and geochemical interpretation of neogene sequences and their zeolitization around Gördes area
FAHRİ ESENLİ
Doktora
Türkçe
1992
Jeoloji Mühendisliğiİstanbul Teknik ÜniversitesiJeofizik Mühendisliği Ana Bilim Dalı
PROF.DR. IŞIK ÖZPEKER