Koni Penetrasyon Ve Presiyometre Deney Sonuçlarının Geoteknik İncelemelerde Kullanımı

Abstract

Mühendislik yapılarının temellerinin oturduğu zeminlerin geoteknik özelliklerinin belirlenmesi ile ekonomik, güvenli tasarım yapılması ve ilerleyen zamanlarda meydana gelebilecek problemlerin en aza indirilmesi mümkündür. Bu amaçla, tüm mühendislik yapılarının inşa edilmesinden önce arazi ve laboratuvar deneyleri ile zeminin araştırılması gerekmektedir. Zemine ait geoteknik parametrelerin bulunabilmesi amacıyla yapılan deneyler, laboratuvar ve arazi deneyleri olarak ikiye ayrılır. Laboratuvar deneylerinin, arazi deneylerine göre bir takım olumsuzluklarından bahsedilebilir. Araziden alınan örselenmiş veya örselenmemiş numunelerin arazideki doğal şartları temsil etmesi neredeyse mümkün değildir. Numune alma işlemi esnasında, zeminin gerilme durumunun değişmesi ya da fiziksel etkiler sebebiyle numune bir miktar örselenir ve böylece araziden ideal örselenmemiş numune alınması mümkün olmaz, kil gibi kendini tutabilen zeminlerde numune almak daha kolay iken kum gibi kendini tutamayan zeminlerde ise numune almak oldukça zor ve masraflıdır. Ayrıca, laboratuvar deneyleri çok kısa sürede yapılamadığı ve laboratuvardaki zemin numunesinin arazideki zeminin çok küçük bir kısmını temsil ettiği unutulmamalıdır. Tüm bu nedenlerden dolayı, zeminin geoteknik özelliklerini belirleyebilmek amacıyla gelişen teknoloji ile birlikte arazi deneyleri laboratuvar deneyleri yanında gittikçe önem kazanmaktadır. Arazide istenilen mesafe ve derinlikte uygulanabilen birçok deney bulunmaktadır. Bu testler sayesinde zemine arazideki doğal hali (gerilme miktarı, su içeriği vb) üzerinde deneyler yapılmasının yanında, zemine ait geoteknik parametreler oldukça hızlı şekilde elde edilebilmektedir. Ayrıca, CPTu ile boşluk suyu basıncı da ölçülebilmektedir. Bu tez çalışması kapsamında Koni Penetrasyon Deneyi (CPT) ve Presiyometre Deneyi (PMT) sonuçlarının bazı geoteknik parametreler ve diğer arazi deneyleri (Sismik kırılma, PS Logging, SPT) ile ilişkisi değerlendirilmiştir. CPT, derinlikle beraber sürekli data sağlaması ve hızlı bir deney olması sebebiyle yumuşak ve gevşek zeminlerde çok kullanışlı bir arazi deneyi olmasının yanında iri çakıllı zeminlerde ve kayaçlarda uygulanamamaktadır. PMT ise her tür zeminde, dolguda ve kayaçta uygulanabilmesi ve zeminin yanal deformasyon-mukavemet özellikleri hakkında bilgiler vermesi açısından tercih edilir. Arazide uygulanan 21 adet Koni Penetrasyon Deneyi (CPT) sonuçları (uç direnci “qc”, çevre sürtünmesi “fs” ve sürtünme oranı “Rf”), laboratuvar sonuçlarına göre belirlenen zemin sınıflandırması, birim hacim ağırlık “γ”, permeabilite katsayısı “k”, drenajsız kayma direnci “cu”, kayma direnci açısı “ϕ”, ön konsolidasyon basıncı “σc’”, aşırı konsolide oranı “AKO”, hacimsel sıkışma katsayısı “mv”, sıkışma modülü “Mc”, uygulanan jeofizik deneyler (55 adet Sismik Kırılma Deneyleri ve 2 adet biri 53.5 m diğeri 57.0 m derinliğinde PS Logging Deneyleri) sonucuna göre de kayma dalgası hızı “Vs” ve arazide uygulanan SPT sonucuna göre SPT/N değeri, presiyometre deneyi sonucunda elde edilen limit basınç “PL” ve Menard modülü “Em” değerleri ve SPT/N’e bağlı olarak bulunan elastisite modülü “E” ile ilişkisi değerlendirilmiştir. Bunların yanı sıra CPT sonuçları kullanılarak sıvılaşma analizi yapılmıştır. Yapılan tüm incelemelerin yanında, CPT sonuçları kullanılarak sıvılaşmanın değerlendirilebileceği CLiq programları sonuçları da sunulmuştur. Arazide uygulanan 256 adet Presiyometre Deneyi (PMT) sonuçları (limit basınç “PL” ve Menard modülü Em”), laboratuvar sonuçlarına göre belirlenen drenajsız kayma direnci “cu”, drenajsız kayma direnci açısı “ϕ”, aşırı konsolide oranı “AKO”, ön konsolidasyon basıncı “σc’”, hacimsel sıkışma katsayısı “mv”, sıkışma modülü “Mc”, uygulanan jeofizik deneyler (55 adet Sismik Kırılma Deneyleri ve 2 adet biri 53.5 m diğeri 57.0 m derinliğinde PS Logging Deneyleri) sonucuna göre de kayma dalgası hızı “Vs”, SPT sonucuna göre SPT/N değeri ve SPT/N’e bağlı olarak bulunan elastisite modülü değeri “E” ile ilişkisi değerlendirilmiştir. CPT sonuçları ile; kayma direnci açısı “ϕ”, aşırı konsolide oranı “AKO”, ön konsolidasyon basıncı “σc’”, kayma dalgası hızı “Vs” değerlerinin ilişkisinin kuvvetli olduğu görülür iken, drenajsız kayma direnci “cu” , sıkışma modülü “Mc” , elastisite modülü “E” ve SPT/N darbe sayısı ile ilişkisinin ise ise orta derecede kuvvete sahip olduğu ve hacimsel sıkışma katsayısı “mv” ve Presiyometre Deney sonuçları “PL, Em” ile ilişkisinin olmadığı görülmüştür. PMT sonuçları ile elastisite modülü “E”, kayma dalgası hızı “Vs” ve SPT/N darbe sayısı arasında kuvvetli bir ilişki görülür iken, drenajsız kayma direnci “cu”, kayma direnci açısı “ϕ”, ön konsolidasyon basıncı “σc’” değerleri ile ilişkisinin orta derecede kuvvetli olduğu ve aşırı konsolide oranı “AKO”, hacimsel sıkışma katsayısı “mv” değerleri ile ilişkisinin ise olmadığı görülmektedir.

It is possible to make a design more economic and more reliable and to reduce the amount of problems with the determination of geotechnical parameters of the soil that underlies the foundation of engineering structures. Accordingly for this purpose, the underlying soil shall be investigated with the help of laboratory and in-situ tests prior to commencement of the construction period of the structures. The tests that are performed to obtain geotechnical parameters have divided in to two categories parts as laboratory tests and in-situ tests. It can be claimed that laboratory tests have some disadvantages when they compared to in-situ tests. The disturbed or undisturbed samples taken from the site shall not represent the natural characteristics of the in-situ soil. During sampling works, the sample shall be disturbed in some degree due to change in the stress conditions or some physical impacts therefore it is not possible to obtain fully undisturbed samples. It is easier to obtain samples in clayey soils however in sandy soils the sampling process shall become arduous and expensive. In addition, it is obligatory to take into account that the laboratory tests shall dure for a log time and the sample, which is taken from the site to conduct the laboratory tests, represents only a small part of the in-situ soil. All because of these reasons, with the help of developing technologies, in situ tests will have a crucial role in order to determine the geotechnical properties of the soil compared to laboratory tests. There exists various kind of in-situ test that shall be conducted in various distance and depth. It is possible to perform the tests on natural soil conditions (soil stress and water content etc) and to obtain the geotechnical parameters very rapidly with the help of these tests. Moreover, the pore water pressure shall be measured with the usage of CPTu. In the scope of this dissertation study, the test results of Cone Penetration Test (CPT) and Pressuremeter Test (PMT) compared with some geotechnical parameters and some other in-situ tests such as seismic refraction, PS logging and SPT. Although CPT is evaluated very beneficial test in terms of providing continuous ground profile and it is rapid implementation for weak and soft soil types, CPT shall not satisfactorily used for gravels and rocks. On the other hand, PMT is more preferable because it is applicable to any kind of soil and rock and also pressuremeter test provides valuable information about the deformation and strength characteristics of the in-situ soil. Many geotechnical parameters of the soil can be obtained by using the limit pressures and Menard Module from the pressuremeter test or cone resistance and side friction values from the conic penetration test of the soil. In the scope of this thesis, the relationship between the in-situ tests and various geotechnical parameters are evaluated. The in-situ tests are, Conic Penetration Test (CPT) and Pressuremeter Test (PMT). In order to evaluate the relationship between geotechnical parameters and CPT-PMT, the test results of the SPT, Seismic refraction, PS Logging data and Laboratory tests results of the Ashgabat and two different project at İstanbul Boğaziçi area were used. Executed 21 Cone Penetration Test (CPT) results (Cone resistance “qc”, sleeve friction “fs” and friction ratio “Rf”) are evaluated taking into consideration laboratory based soil classification and soil parameters such as unit weight “γ”, permeability “k”, undrained shear strength “cu”, friction angle “ϕ”, pre-consolidation pressure “σc’”, over consolidation ratio “AKO”, volumetric compression modulus “mv” and compression modulus “Mc” have been determined according to the laboratory and in-situ CPT data; parameters such as shear wave velocity “Vs” have been determined according to the geophysical tests (55 number of Seismic refraction test and 2 number of PS Logging tests with a depth of 53.5 and 57.0 ); the pressuremeter test results (limit pressure “PL” and Menard modulus “Em”) have been compared with elastic modulus “E” calculated from SPT. Additionally, liquefaction analyses have been performed using CPT data. Moreover, the results of Cliq software which is a helpful tool for evaluation of liquefaction risk, have been presented. Cone resistance and friction ratio which are calculated from the CPT result are used to make a soil classification as numbered each soil type on a related chart. The soil numbers on the chart that is developed by the Lunne, Robertson ve Powell (1997) and soil classification obtained from the laboratory test results show compatibility Additionally, in the mentioned chart that is used for the soil classification based on the cone resistance and the friction ratio values that is calculated from the Cone Penetration Test, the natural unit weight and permeability coefficient belong to the numbered soil class also show compatibility with the laboratory test results that was executed on the samples taken from the boreholes that is close to the CPT points The relationship between qc, fs, Rf values calculated from the CPT and undrained shear strength “cu” which is calculated from the unconfined test are evaluated and as a result of this evaluation, it is understood that the relationship between the qc-cu shows moderate compatibility and on the other hand, by increasing the cone resistance, undrained shear strength is also increase. The relationship between qc, fs, Rf values calculated from the CPT and friction angle “ϕ” which is calculated from the direct shear test in the laboratory are evaluated and as a result of this evaluation, it is understood that the relationship between the qc-ϕ shows high compatibility and also it is observed that, by increasing the cone resistance, friction angle is also increase. The relationship between qc, fs, Rf values calculated from the CPT and over consolidation ratio (OCR) which is calculated from the consolidation test in the laboratory are evaluated and as a result of this evaluation, it is understood that the relationship between the qc-OCR shows high compatibility and also it is observed that, by increasing the cone resistance, over consolidation ratio is also increase. The relationship between qc, fs, Rf values calculated from the CPT and pre-consolidation pressure “σc’” which is calculated from the consolidation test in the laboratory are evaluated and as a result of this evaluation, it is understood that the relationship between the qc-σc’ shows high compatibility and also it is observed that, by increasing the cone resistance, pre-consolidation pressure is also increase. The relationship between qc, fs, Rf values calculated from the CPT and volumetric compression coefficient “mv” which is calculated from the consolidation test in the laboratory are evaluated and as a result of this evaluation, it is understood that there has no relationship between the related values. The relationship between qc, fs, Rf values calculated from the CPT and compression module “Mc” which is calculated from the consolidation test in the laboratory are evaluated and as a result of this evaluation, it is understood that the relationship between the qc-Mc shows moderate compatibility and also it is observed that, by increasing the cone resistance, compression module is also increase. The relationship between qc, fs, Rf values calculated from the CPT and Elasticity Module “E” which is calculated from the SPT blow numbers are evaluated and as a result of this evaluation, it is understood that the relationship between the qc-E shows moderate compatibility and also it is observed that, by increasing the cone resistance, Elasticity module is also increase. The relationship between qc, fs, Rf values calculated from the CPT and Shear wave velocity “Vs” which is calculated from the Seismic refraction and PS Logging test are evaluated and as a result of this evaluation, it is understood that the relationship between the qc-Vs shows high compatibility and also it is observed that, by increasing the cone resistance, Shear wave velocity is also increase. The liquefaction potential that is calculated from the CPT results in the subjected area is compared with laboratory test results executed on the samples taken from the boreholes that are close to the CPT application and the results with the CLiq software. According to the comparison result, the liquefaction risk is observed at the same level. The relationship between qc, fs, Rf values calculated from the CPT and “SPT/N” which is calculated from the in-situ test such as SPT are evaluated and as a result of this evaluation, it is understood that the relationship between the fs-SPT/N shows moderate compatibility and also it is observed that, by increasing the side friction, elasticity module is also increase. The relationship between qc, fs, Rf values calculated from the CPT and Limit pressure “PL” and Menard Module “Em” which is calculated from the Pressuremeter test are evaluated and as a result of this evaluation, it is understood that there has no relationship between the related values. The relationship between “PL and Em” values calculated from the Pressuremeter test (PMT) and undrained shear strength “cu” which is calculated from the unconfined test are evaluated and as a result of this evaluation, it is understood that the relationship between the PL-cu shows moderate compatibility and also it is observed that, by increasing limit pressure, undrained shear strength is also increase. The relationship between “PL and Em” values calculated from the Pressuremeter test (PMT) and friction angle “ϕ” which is calculated from the direct shear test in the laboratory are evaluated and as a result of this evaluation, it is understood that the relationship between the PL-ϕ shows moderate compatibility and also it is observed that, by increasing the limit pressure, friction angle is also increase. The relationship between “PL and Em” values calculated from the Pressuremeter test (PMT) and over consolidation ratio (OCR) which is calculated from the consolidation test in the laboratory are evaluated and as a result of this evaluation, it is understood that there has no relationship between the related values. The relationship between “PL and Em” values calculated from the Pressuremeter test (PMT) and pre-consolidation pressure “σc’” which is calculated from the consolidation test in the laboratory are evaluated and as a result of this evaluation, it is understood that the relationship between the qc-σc’ shows moderate compatibility and also it is observed that, by increasing the limit pressure, pre-consolidation pressure is also increase The relationship between “PL and Em” values calculated from the Pressuremeter test (PMT) and volumetric compression coefficient “mv” which is calculated from the consolidation test in the laboratory are evaluated and as a result of this evaluation, it is understood that there has no relationship between the related values. The relationship between “PL and Em” values calculated from the Pressuremeter test (PMT) and Elasticity Module “E” which is calculated from the SPT blow numbers are evaluated and as a result of this evaluation, it is understood that the relationship between the PL-E shows high compatibility and also it is observed that, by increasing the limit pressure, Elasticity module is also increase The relationship between “PL and Em” values calculated from the Pressuremeter test (PMT) and Shear wave velocity “Vs” which is calculated from the Seismic refraction and PS Logging test are evaluated and as a result of this evaluation, it is understood that the relationship between PL-Vs shows high compatibility and also it is observed that, by increasing limit pressure, Shear wave velocity is also increase. The relationship between “PL and Em” values calculated from the Pressuremeter test (PMT) and SPT blow numbers which is calculated from the in-situ test SPT are evaluated and as a result of this evaluation, it is understood that the relationship between the PL-SPT/N shows high compatibility and also it is observed that, by increasing the limit pressure, elasticity module is also increase Soil parameters acquired from 256 Pressuremeter Tests (PMT) results (limit pressure “PL” and Menard modulus “Em”), laboratory tests such as undrained shear strength “cu”, undrained friction angle “ϕ”, over consolidation ratio “AKO”, pre-consolidation pressure “σc’”, volumetric compression modulus “mv” and compression modulus “Mc” and the soil parameters provided from geophysical tests (55 number of Seismic refraction test and 2 number of PS Logging tests with a depth of 53.5 and 57.0) such as shear wave velocities “Vs” have been compared with elastic modulus “E” calculated from SPT data. The relationship between CPT results and undrained friction angle “ϕ”, over consolidation ratio “AKO”, pre-consolidation pressure “σc’”, shear wave velocity “Vs” is evaluated as very strong however, the relationship between CPT and undrained shear strength “cu”, compression modulus “Mc”, elastic modulus “E” and SPT/N values is evaluated as moderately strong and moreover there has seen no relationship with volumetric compression modulus “mv” and Pressuremeter Test results “PL, Em”. The relationship between PMT results and elastic modulus “E”, shear wave velocity “Vs” and SPT/N is evaluated as very strong however the relationship between PMT and undrained shear strength “cu”, undrained friction angle “ϕ”, pre-consolidation pressure “σc’” is moderately strong, moreover there has seen no relationship with over consolidation ratio “AKO” and volumetric compression modulus “mv”.