Kazıkların eksenel ve yatay yük taşıma kapasiteleri
The bearing capacity of piles under axial and lateral loading
- Tez No: 46166
- Danışmanlar: PROF. DR. AHMET SAĞLAMER
- Tez Türü: Yüksek Lisans
- Konular: İnşaat Mühendisliği, Civil Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1995
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 202
Özet
Bu çalışmada, kazıkların eksenel ve yatay yük taşıma kapasitelerinin hesap yöntemleri ve yapılan araştırmalar hakkında bilgi verildikten sonra bu alanda kullanılan APILE1, APELE2 ve LPILE bilgisayar programlan tanıtılacak, programlar kullanılarak çözülmüş örneklere de yer verilecektir. Çalışmada APILE1, APILE2 ve LPILE programlarının tanıtımından önce teorik bilgiler verilmeye çalışılmıştır. 2. bölümde kazıklar hakkında genel bir tanıtım yapıldıktan sonra 3. bölümde kazıklı temellerin taşıma gücü hakkında bilgiler verilmiştir. Ayrıca bu bölümde kazıkların eksenel taşıma kapasitelerini hesaplamak için kullanılan yöntemler ve bu yöntemlerden biri olan kazık yükleme deneyine uygulamadan bir örnek verilmiştir. 4. bölümde ise kazıkların taşıma kapasitelerinin hesaplanmasında önemli rol oynayan kazık - taşıyıcı zemin etkileşimi konu edilmiştir. 5. bölümde derin temellerdeki yük dağılımı konusu işlenmiştir. Eksenel yükleme altındaki kazık gruplarının taşıma kapasitesi ve kazık grubunun oturma değerleri hakkındaki bilgileri 6. bölümde bulmak mümkündür. 7. bölümde kazıkların eksenel taşıma kapasitelerinin hesabında kullanılan APILE1 bilgisayar programı, programın hesap esasları ve programa veri girişi anlatılmıştır. 8. bölüm eksenel yüklü kazıklarda yük iletimi ve kazık oturma değerinin saptlanmasında kullanılan APILE2 bilgisayar programı ve bu programa veri girişi hakkında bilgi vermektedir. APILE2 bilgisayar programının hesap yöntemi 5. bölümde anlatılan yöntemleri esas almaktadır. APILEl ve APILE2 programlan kullanılarak çözülmüş örnek probleme de 8. bölüm içinde yer verilmiştir. 9. bölümde kazıkların yatay yük taşıma kapasiteleri ve nihai yatay deplasman hesap yöntemleri anlatılmış ve bu alanda kullanılan LPILE bilgisayar programının tanıtımı ve örnek problem çözümü 10. bölümde verilmiştir. 3. bölümde anlatılan kazık yükleme deneyine ait okuma değerleri ve diyagramlar ekler bölümünde sunulmuştur. XV111
Özet (Çeviri)
Pile foundations are the deep foundations to transfer loads from superstructure through weak compressible soil strata to suffer or more compact soils or onto rocks. In the design of pile foundations, the main question is to evaluate the ultimate bearing capacity of a single pile for a given soil profile and pile type. In slightly cohesive or non - cohesive soils it is difficult to recover undisturbed samples and to conduct laboratory tests on these samples for determining the strength and deformation properties of the soils. The recommended correlations between the bearing capacity of axially loaded piles and the field tests such as SPT, CPT and MPT are described. 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 results of field investigations, laboratory testing and empirical and semi empirical methods. These estimated values should then be confirmed by field pile load tests. It is possible to obtain information about the future behaviour of the project piles by performing load tests. Load test is a preferred system to determine the bearing capacity of various type of piles 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 office study. Pile load tests are then carried out to refine and finalize the design. For these conditions, the test piles are generally tested to failure. 2. Test on a Working Pile : In areas where 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 these situations, the piles are generally tested to two times the design capacity. The computation of the capacity of a single pile under axial loading is by no means a straight forward exercise. There are two principal reasons for the rapid changes in design approaches. 1. The lack of high quality data in the technical literature from the results of full - scale testing of piles under axial loading. The measurements are frequently questionable and the methods of testing are not very consistent. Many techniques are being used to obtain properties of in situ soil, data from the testing methods are frequently missing, and the interpretations of soil - test results are inconsistent xixbetween investigators. Furthermore, only in rare instances have measurements been made, using the necessary instrumentation, that reveal the detailed manner in which the foundation interacts with the supporting soil. 2. The interaction between a pile and the supporting soils involves many complexities. The soil is altered by pile installation, for example, and there are many other important factors that influence the response of a pile under axial loading. A fundemental method of investigating the behaviour of a pile under axial load is to instrument the pile so that the distrubition of load with depth can be measured. A load test can then yield much valuable information. Along with the measurements along the pile, the investigator must measure accurately the load and the downward movement at the top of the pile. With the above data, it is possible to develop experimental T-z curves for the soil surrounding the pile. The residual stresses which exist in the pile at the time of the installation will tend to obscure to some extent the pile behavior. A useful technique which may be employed is the sampling or in situ testing of soils next to the pile wall subsequent to pile driving ; such tests have been useful in estimating the final conditions of the soil. The installation of total - pressure gauges and porewater - pressure gauges in the wall of a pile has given useful results. These gauges can be installed with a small expense and the collection of a volume of such data can add to the understanding of pile - soil interaction. Pile - soil behavior can be investigated in the laboratory by modelling a segment of a pile. Studies can simulte the effects of a pile driving as well as the load transfer after the system has reached equilibrium. Both normally consolidated and overconsolidated soils can be investigated. The studies to date have used small piles (rods) and relatively small soil specimens. There appears to be a significant advantage of extending this concept to specimens of a large size. Selection of the procedures for the design of deep foundations has been an important problem for geotechnical engineers and will continue to be so. Many important structures at on shore sities are being placed. Where soil conditions are favorable offshore structures are moving to deeper water where very large piles are placed in closely spaced groups or where innovative foundation designs will subject the piles to an unusual combination of loads. The effects of driving piles into clay or sand are presented as well as the effects of installing a bored pile ( drilled shaft, drilled pier, caisson). Some of the effects of loading are discussed, with four kinds of loading being recognized : short - term ( static), sustained, cyclic and dynamic. The use of the wave - equation method for predicting the behavior of driven piles was employed in. 1938. The method appears to describe reasonably well the behaviour of the pile during driving if soil parameters can be properly selected. The selection of XXsoil parameters has advanced only slightly since the Smith proposal. The existence of residual stresses in a pile after its installation can be explained by the wave - equation model. The driving of a pile without some lateral vibration is almost impossible, and some investigators have attributed important consequences in pile behavior to the effects of lateral vibrations. There is evidence to indicate that pile driving causes clay near the ground surface to be pushed back and a slight space to develop at the interface between the interface and the soil. The depth that such a space can exist is obviously greater for a stiff clay than for a soft clay. Computer program APILE1, is progressed for analysis of the axial capacity of piles. Methods of Computation of APILE1: APILE1 is designed to deal with the all straight- sided sections, starting with an open - ended pipe. This latter case is more complex that closed - ended pipes or solid sections because provisions are made in the program to compute the resistance of a soil plug that will move inside the pipe during driving. A simple expedient is employed in the program to convert the open - ended one or to a solid section. In practice, the lower end of a pipe pile may have a thick wall so as to eliminate the possibility of a damage due to driving stresses. The lower section can be assumed to have a wall thickness sufficient to close the pipe; hence, a closed - ended pipe or a solid section can be analyzed. The use of the equations of statics to compute the capacity of piles is well established and numerous procedures have been suggested. The employed methods of computation of APILE1 are presented by the American Petroleum Institute in their manual on recommended practice. The API procedures for clay are based essentially on the use of undrained shear strength and, of course, are largely emprical. The API procedure for sand is also strongly empirical but effective - stress techniques are naturally employed because no excess porewater pressures are assumed. One other method is employed in the computations, the so - called Lambda method ( Kraft, et al, 1981); an earlier version of the method was published in 1972 ( Vijayvergiya and Focht ). The method has been used extensively in offshore practice. A general method is programmed by which the user may input unit values of skin friction and end bearing as a function of depth. The user is urged to use any and all of the methods that apply to a particular soil profile. Furthermore, multiple runs should be made in which the soil parameters are varied through a range that could be expected. The settlement of the top of the pile is made up of two quantities: 1 ) Compression in the pile due to the applied load, 2) The settlement of the pile tip. This downward movement is dependent on the applied load, on the position along the pile, on the stress - strain characteristics of the pile material, and on the load transfer - movement curves along the pile shaft and at the pile tip. To solve the problem of the X\Jdistrubution of load along the pile for a given applied load and the determination of downward movement at any point along the pile, a nonlinear differential equation must be solved. Computer program APILE2, is progressed for analysis of load versus settlement for an axially loaded deep foundation. Methods of Computation of APILE2: The information presented in APILE2 relates to short - term settlement. Settlement due to the consolidation of soft clay must be computed separately and added to the short term settlement. Also, long - term settlement of cohesionless soil, perhabs due to vibration must be treated separately. There is at present a considerable degree of uncertainty about computation of short - term settlement. The fundamental problems in computing a load - settlement curve, and curves showing the distribution of axial load as a function of distance along the pile, are to: Select curves that show load transfer in side resistance (skin friction) as a function of pile movement at the point in question ( t - z curves), and a curve showing end bearing as a function of movement of the pile tip ( q-w curve ).“ t ”is referred to as a ratio of unit skin friction to shear strength in the original definition for t - z curves,“f ”is defined as the unit skin friction and“ w”is defined as the pile movement. The best way to investigate the behavior of piles under lateral loading is to instrument a pile for measurement of bending moment as a function of depth. If the experiment is conducted properly, curves can be developed showing the soil resistance as a function of pile deflection. The p - y curves so developed provide a basis for improving the methods of predicting such curves ; thus, improved understanding of the behavior of piles under lateral load will be developed. Piles that support lateral loads must be analyzed such that both the conditions of equilibrium and compatibility are satisfied. To satisfy these two conditions, the solution of the problem requires that the soil resistance be consistent with pile deflection and that the pile deflection be computed with the proper distribution of soil resistance. Some consideration of the nature of the soil resistance in response to pile deflection will reveal that the soil resistance is a nonlinear function of pile deflection and depth along the pile. If the assumption can be made that the soil resistance can be given by a family of curves that show p as a function of x and y, at any point along the pile x, one can express p as p = -Esy where Es = a form of soil modulus ( the minus sign merely reflects that the soil resistance acts in the opposite direction to deflection ). XXIIIt would obviously be desirable if the soil reaction p could be found analytically for any depth below the ground surface and for any pile deflection. Factors to be considered are pile geometry, soil properties, and the methods of loading, whether static, cyclic, sustained or dinamic. At the current time the methods of analysis are inadequate for solving the entire problem. However, approximate solutions can be obtained for the ultimate soil resistance pu that could develop at any depth. At points some distance below the ground surface the value of pu is found by assuming that the soil particles move horizontally; that is at some depth it is easier for the soil to flow from the front of the pile to the back of the pile rather than to move upward. Some elementary theory can be employed to get some numerical values that can help define a p - y curve. The method of analysis, employing numerical p - y curves; has been used to generate curves giving pile - head deflection as a function of applied load; the analytical curves are then compared to one obtained from experiment. The four types of loading are static, repeated, sustained, and dynamic. The statics p - y curves can be thought of as backbone curves that can be correlated to some extent with soil properties. Thus, the curves are useful for the purpose of providing some theoretical basis to p - y method. From the standpoint of design, the static p - y curves have application in the following cases: where loadings are short - term and not repeated and for sustained loadings, as in earth - pressure loadings, where the soil around the pile is not susceptible to consolidation and creep. There are many instances in which pile - supported structures are subjected to cyclic loading. Some of the cases are; wind load against overhead signs and high - rise buildings, traffic loads on bridge structures, wave loads against offshore structures, impact loads against docks and dolphin structures, and ice loads against locks and dams. Sustained loading is: if the soil that is effective in resisting the lateral deflection of a pile is an over - consolidated clay, the influence of sustained loading would probably be small. The maximum lateral stress from the pile against the clay would probably be less than the previous lateral stress; thus, the additional deflection due to consolidation and creep in the clay should be small or negligible. Two types of problems involving dynamic loading are frequently encountered in design: machine foundations and earthquakes. A computer program LPILE is introducted for the analysis of laterally loaded pile program in the thesis. This software has been generated by L. C Reese at Texas University. Details of the software is explained in detail, in the thesis. Following the detailed study of ultimate load capacity of piles under vertical and horizontal loads practical examples are solved. İzmit Integrated Environmental Project which is being constructed in İzmit in comprised of three main parts, namely Waste Water Treatment Plant, Interceptors and a Sanitary Land Fill. Waste Water Treatment Plant and 18 KM long interceptors are being constructed in very soft soil XXIUconditions, Therefore sedimentation tanks, oxidization tanks and other units of the treatment plant are to rest on vibrex piles of D= 609 mm diameter. Soil profile encountered at the treatment plant site are summarized in the thesis and vertical bearing capacity of D= 609 mm vibrex piles are computed by the implemantation of APDLE1 and APHJE2 computer programs. Horizontal displacements of a single pile under design loads are also computed by the implemantation of LPILE program. Inputs and outputs of these practical problems are given in the thesis. Determination of ultimate pile capacity by pile - load tests are also studied in Chapter 3. In this chapter some empirical methods suggested by some researchers for the prediction of ultimate bearing capacity of a pile based on the results of a pile - load test are also outlined. The pile - load test that was carried out at the treatment plant site is analysed in this sense and the full data of the test is given. XXIV
Benzer Tezler
- Kum zeminlerde, yatay yüklü baret kazıkların davranışının belirlenmesi
Determination of behaviour of barrette piles under lateral load in sand
MURAT OKAR
Yüksek Lisans
Türkçe
2018
Mühendislik Bilimleriİstanbul Teknik Üniversitesiİnşaat Mühendisliği Ana Bilim Dalı
DR. ÖĞR. ÜYESİ BERRAK TEYMÜR
- Data-driven modeling of ultimate load capacity of closed- and open-ended piles using machine learning
Kapalı ve açık uçlu kazıkların nihai taşıma kapasitelerinin makine öğrenmesi kullanılarak veriye dayalı modellenmesi
EMİRHAN ALTINOK
Yüksek Lisans
İngilizce
2021
İnşaat Mühendisliğiİstanbul Teknik Üniversitesiİnşaat Mühendisliği Ana Bilim Dalı
DOÇ. DR. MEHMET BARIŞ CAN ÜLKER
- Viyadük ayaklarında bulunan kazık gruplarının yanal ve düşey yük etkilerine karşı farklı yöntemlerle modellenmesi
Modelling of pile groups beneath viaduct piers under lateral and vertical loads using different approaches
KEMAL SEVİNER
Yüksek Lisans
Türkçe
2022
İnşaat MühendisliğiGazi Üniversitesiİnşaat Mühendisliği Ana Bilim Dalı
PROF. DR. NİHAT SİNAN IŞIK
- Numerical modelling for the pile systems of berthing structures
Kazıklı iskelelerin matematiksel modellemesi
TUFAN ŞİRİN
Yüksek Lisans
İngilizce
2001
Mühendislik BilimleriDokuz Eylül ÜniversitesiDeniz Bilimleri ve Teknolojisi Ana Bilim Dalı
Y.DOÇ.DR. GÖKDENİZ NEŞER
- Basınç tipi zemin ankraj davranışının sayısal analizler ve saha deneyleri ile incelenmesi
Investigation of compression ground anchor behaviour through numerical analyses and field tests
GÖKALP DEMİRCİ
Yüksek Lisans
Türkçe
2024
İnşaat Mühendisliğiİstanbul Teknik Üniversitesiİnşaat Mühendisliği Ana Bilim Dalı
PROF. DR. RECEP İYİSAN