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

Procjena amplifikacijskih efekata površinskih slojeva tla i dinamičko ponašanje tla u Nikoziji na Cipru

Single-station microtremor measurements were conducted to investigate earthquake and soil behaviour for the first time in Nicosia, Cyprus. Cyprus is located in a tectonically complex area in the Eastern Mediterranean where three plates meet. The study area was chosen to cover the areas to be opened for new development. Nicosia, the capital of Cyprus, is also the island\u27s most important cultural, industrial, commercial, and transportation centre. The study creates base maps for the soil to assess earthquake resistance crucial for construction. Microtremor Method was applied at 100 stations and the Multi-Channel Analysis of Surface Waves (MASW) method was used at 52 stations. Also, RefractionMicrotremor (Re-Mi) and L-Shaped Spatial Autocorrelation (L-SPAC) methods were carried out at 17 stations to substantiate the research. The results of the microtremor method indicate that the predominant soil period values have an average of 1 second and pre-dominant peak period values are generally found between 0.1 to 5 s at the study area. Peak amplitude values are observed between 1 and 2.4. The Vulnerability Index Parameter (Kg) exceeded 20 at the central and the southern stations, and Kg values change between 7 and 54 units. The Kg values were found to be higher than 20 in soils where shear wave velocity is lower than 760 m/s. At the same time, the values of the predominant peak period were greater than 1 second. Cyprus is located in the Alpine Himalayan earthquake zone. The Cyprus Arc is known as the main seismic source of the island, It constitutes the tectonic border among African and Eurasian lithospheric plates in the region. During an earthquake in Nicosia, seismic waves will be amplified by an average of 1.5 times and soil deformation will occur due to the exceeding elastic limits. The results provided important insight into soil behaviour and indicated its reactions in a potential earthquake.Mjerenja mikroseizmičkog nemira provedena su po prvi puta u Nikoziji na Cipru radi istraživanja ponašanja tla tijekom potresa. Cipar se nalazi u tektonski složenom području na istočnom Mediteranu gdje se susreću tri tektonske ploče. Istraživano područje odabrano je tako da uključi prostor planiran za novu gradnju. Nikozija je glavni grad Cipra, ujedno i najvažnije otočno kulturno, industrijsko, trgovačko i prometno središte. Za okrug Nikozija cilj je izračunati i objaviti osnovne karte tala da bi se procijenila potresna otpornost kako postojećih tako i novih zgrada. Mjerenja mikroseizmičkoga nemira obavljena su na 100 lokacija, a metoda višekanalne analize površinskih valova (MASW) na 52 lo-kacije. Također, na 17 lokacija provedene su metode refrakcijskog mikrotremora (Re-Mi) i L-Shaped Spatial Autocorrelation (L-SPAC) kako bi se povećala dubina istraživanja. Rezultati dobiveni analizom mikroseizmičkog nemira pokazuju da su prevladavajuće vrijednosti vlastitoga perioda tla oko jedne sekunde, a prevladavajuće vrijednosti perioda s najvećom amplifikacijom uglavnom su između 0.1 i 5 s. Vrijednosti vršne amplitude uglavnom su između 1 i 2,4. Parametar indeksa povredljivosti (Kg) prelazi 20 na središnjim i južnim lokacijama, a vrijednosti Kg općenito variraju između 7 i 54 jedinice. Vrijednosti brzine posmičnog vala u prvih 30 m dubine na mjestima gdje su vrijednosti indeksa Kgveće od 20, manje su od 760 m/s. Istodobno su predominantni periodi bili veći od 1 sekunde. Cipar se nalazi u alpskom himalajskom području potresa. Ciparski luk poznat je kao glavni seizmički izvor otoka. On čini tektonsku granicu između afričkih i euroazijskih litosferskih ploča u regiji. Tijekom potresa u Nikoziji, seizmički valovi pojačat će se u prosjeku 1,5 puta i doći će do deformacije tla zbog nadmašenih granica njegove elastičnosti. Rezultati su pružili važan uvid u ponašanje tla tijekom mogućih potresa