Kazık yükleme deneylerinden kazık göçme yükünün tahmin edilmesi
Başlık çevirisi mevcut değil.
- Tez No: 75389
- Danışmanlar: PROF. DR. REMZİ ÜLKER
- Tez Türü: Yüksek Lisans
- Konular: İnşaat Mühendisliği, Civil Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1998
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: İnşaat Mühendisliği Ana Bilim Dalı
- Bilim Dalı: Geoteknik Bilim Dalı
- Sayfa Sayısı: 115
Özet
ÖZET Bu çalışmada kazıklı temeller hakkında bilgi verildikten sonra, kazık taşıma gücünün hesap edilme yöntemleri açıklanacaktır. Kazık yükleme deney sonuçlarına dayanılarak kazık göçme yükü tahmin metodları incelenerek, uygulamadan örneklere yer verilecektir. Çalışmada kazak göçme yükü tahmin metodlarının incelenmesinden önce kazıklar ve kazıklı temeller hakkında bilgi verilmeye çalışılmıştır. Bölüm 3'de kazıklı temellerin taşıma gücü hesap yöntemleri incelenmiştir. Kazık yükleme deney sonuçlarından yararlanılarak, toplam oturma eğrisi, kalıcı oturma eğrisi, kalıcı ve elastik şekil değiştirme kriterleri kullanılarak kazık taşıma kapasitesi belirleme yöntemleri incelenmiştir. Bölüm 4' de kazık göçme yükünün önemi, belirleme yöntemleri ve bu yöntemlerin mukayeseleri ve yorumlan ele alınmıştır. Hesaplamaların yapılabilmesi için Davisson, Chin, De Beer, Mazurkiewicz Fuller ve Hoy, Butler ve Hoy yöntemleri ile,%80 Brinch Hansen ve %90 Brinch Hansen kriterleri kullanılmıştır. Bölüm 5 'de uygulaması yapılan çakma kazıklar (vibreks, franki tipi ve H profilli çelik) ile fore kazıklar(normal ve ucu genişletilmiş) için göçme yükleri grafik metodlar kullanılarak hesaplanmıştır. Elde edilen sonuçlara dayanılarak kazık tipi yükleme metoduna uygun göçme yükü tahmin metodlan önerilmiştir.
Özet (Çeviri)
THE DETERMINE OF THE ULTIMATE FAILURE LOAD FOR THE PILE LOAD TESTS SUMMARY Pile foundations are the deep foundations to transfer loads from superstructure trough weak compressible soil strata to suffer or more compact soils or onto rocks. In the design of pile foundation, the main question is to evaluate the ultimate bearing capacity of a single pile for a given soil profile and pile type. The accurate determination of pile bearing capacity is very important in the design of a piled foundation system in order to obtain a safe and economic structure. The estimation of a pile load capacity and settlement under a load is based on the result of field investigations, laboratory testing and empirical and semi empirical methods. These estimated values should then be confirmed by field pile load tests. Its possible to obtain information about the future behaviour of the project piles by performing load tests. Load tests is a preferred system to determine the bearing capacity of various type of pile in all kinds of soil. In other words, pile load test is accepted as real model test. Pile load tests, in practice, are normally executed in two alternative ways: 1. Test Pile : Preliminary pile design is first carried out on the basis of site investigations, laboratory soil testing and offive study. Pile load tests are then carried out to refine and finalize the design. For these conditions, the test pilesare generally tested to failure. 2. Test on a Working Pile: In areas whwre previous experience is available, pile design is carried out based on the site investigations, laboratory soil testing and office study. Pile load tests are then carried out on randomly selected actual piles to check the pile design capacities. In thesh situations, the piles are generally tested to two times the design capacity. The bearing capacity of a pile is dependent on the size, shape and type of pile and on the properties of the soil in which itis embedded. The ultimate bearing capacity is the load at which the resistance of the soil becomes fully mobilized. At a load greater than the ultimate bearing capacity the soil under goes shear failure, allowing the pile to penetrate into the ground, to become, in effect, a different pile from that originally installed, with a greater embedded length possibly with differnt conditions. The ultimate bearing capacity of a pile may be calculated; a) By means of static formula on the basis of soil test b) By means of static formula on the basis of soil test c) By insitu test ( CPT, SPT ) d) By pile - loading test By using a static formula an estimated value of the ultimate baering capacity of a typical pile is obtained, the accuracy being dependent on the reability of the formula and the soil strenght data to which it is applied. The actual ultimate bearing capacity Xllof any particular pile will differ from this value in so far as the soil surrounding it has properties different from those used in the calculation. By using a dynamic formula an estimate of the ultimate bearing capacity may be obtained from the driving characteristics of each individual pile, the accuracy being dependent on the reliability of the formula, the conditions of use and the data used. A pile load test consists of applying increment of static load to a test pile and measuring the deflection of the pile. The test loads may be applied by direct load from a platform on which water tanks are placed, by jacking against an existing structure, thus reducing the amount of load needed. Alternativly the test pile may be driven in by hydraulic jack bearing against a rijit beam supported on trwo more firmly driven anchor piles. The anchor piles should be a clear distance from the test pile or pile group at least five times the maximum diameter of the largest anchor or test pile but not less than 2 m. Whichever method of loading is used it should be possible to load the pile gradually and remove the load completely after each increment has been applied. A static pile load test can be conducted for any or all of three reasons: 1. To indicate for the contractor the type of driving conditions that will be encountered on the job at hand. 2. To furnish information to the soil engineer to develop driving criteria. 3. To obtain test data needed to convince the building authorities that pile is adequate to support the design load. Practising engineers and researchers have used many pile load test methods that have been reported in several publications (ASTM D 1143-81). From the available numerous load test methods the following four methods can be identified as the basic load test methods (Joshi and Sharma, 1987): 1. Slow Maintained Load Test Methods (SM Test) 2. Quick Maintained Load Test Method (QM Test) 3. Constant Rate of Penetration Test Method (CRP Test) 4. Swedish Cyclic Test Method (SC Test) Generally load and settlement test data are plotted with load along the abscissa and settlement along ordinate. The plotted settlement could either be gross or the net. These plotted data are then used to estimate the failure load so that allowable pile capasity can be calculated. Despite the numerous test which have been carried out and the many papers which have reported on such tests and the analysis thereof, the understanding of pile test loading in current engineering practice leaves much to be desired. The reason for this is that the engineers have concerned themselves with mainly only one questions: ' Does the pile have a certain least capacity' finding little of practical value in analysing the actual capacity and pile - soil interaction. On many projects pile load tests are carried out as a part of the field investigation program, and on the basis of the results of these full scale pile load tests, pile capacities are established. One of xincriteria for establishing allowable pile capacities is to estimate the ultimata pile load capacity then to apply an appropriate safety factor. Prediction of the ultimate pile capacity from pile load tests is, therefore, an important aspect of pile design. This paper first reviews various pile load test methods and the available ultimate load prediction or interpretation methods. These interpretations methods have then been applied on seven pile load test data. These test piles consisted of two bored and belled piles, one normal bored pile, two franki types piles, one vibrex type pile and one driven steel H pile. Applicability of these load test interpretation methods for these different pile types has finally been discussed. The ultimate failure load is defined as the load when the pile plunges or the settlements occure rapidly under sustained load. Other definitions of failure consider arbitrary settlement limit such as, the pile is considered to have failed when the pile head has moved 10% of the pile end diameter of the failure load is at the intersection of the initially tangent to the load-movement curve and tangent to or extension of the final portion of the curve. All these definitions are judgemental. Afailure definition should be based on some mathematical rule and should provide a repeatable value. This value should be independent of scale effects and individual opinion. Methods og determining failure loads from compression pile load tests calculated from nine way. First these methods are reviewed and their applicability for different pile type discussed. These methods are: 1. Davisson Methods ( 1 972) 2. Chin Method (1970-71) 3. De Beer Method (1967) 4. Brinch Hansen 90% Criterion ( 1 963) 5. Brinch Hansen 80% Criterion ( 1 963) 6. Mazurkiewicz Method ( 1 972) 7. Fuller and Hoy Method ( 1 970) 8. Butler and Hoy (1977) 9. Vander Veer Method (1953) Two bored and belled piles, one normal bored pile, two franki types piles, one vibrex type pile and one driven steel H pile.were tested by the Slow Maintaned Test Method (SM) as per ASTM D 1143-81. Table A. provides a summary of failure loads for these eight types of piles. XIVTable A. Failure loads interpreted by various methods for all types of piles There are nine methods to obtain pile failure load. These graphical methods are shown in below figures. Load (ton) X / X-O.U + D/120 9 Q-(AE/L)A Movement (twai Figure 1 Davisson Method i/Q 4/Q-aiA + aj Qu“”l/a< Movement^ mm; Figure 2. Chin Method LogQ t Quitimme Log d Q( ran ].WOQu i(an) Figure 3.De Beer Method Figure 4. %90 Brinch Hansen Method xv.folQ*. Qtt-- W«A Man) Movement ( mm ) Figure 5.%80 Brinch Hansen Method Figure 6. Mazurkiewicz Method Load (toat' Load (ion) 0.05 Tangent paratel to elastic line Movement ( mm) Movementf mm) Figure 7.Fuiler&Hoy Method Figure 8.Butler&Hoy Method ln((l-Q)/(Qu)l 4 Movement ( nun ) Figure 9.Vander Veen Method XVI
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