Experimental And Numerical Investigations On Uplift Behaviour Of Plate Anchors In Cohesionless Soil

In this study, series of small scale laboratory pull-out tests were conducted on anchors embedded in sand. Model tests were performed in a test box. The effects of embedment ratioof anchor plates and relative density of sand on uplift capacity behaviour were investigated.Also numerical analyses of the test models were carried out using the finite element package Plaxis. Based on the results, it can be concluded that the embedment ratio of anchor plates and relative density of sand are main parameters that affect the uplift capacity of anchor plates. Atthe end of the study, the results of experimental study were also compared with the results of numerical solutions

Investigation of the Size Effect at Different Geometries on Stress Distribution of Sandy Soils

In this study, the induced vertical soil stress values occuring along with horizontal surfaces at predetermined depths of the shallow foundations on sandy soils were investigated by model tests. In the model tests pressure transducer was used to measure the stresses.Circular foundations at different size were used in the model tests and the size effect were investigated. As a result of this study, the size effect at circular foundations wasn't found tobe an important factor on stress distribution of sandy soils

Zeminlerin Mekanik Davranışının Modellenmesi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2008Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2008Zemin–yapı etkileşimi problemlerinde, zeminin cinsi, rijitliği ve deformasyon özellikleri çok önemlidir. Araştırmacılar genellikle, üst yapı davranışı üzerinde yoğunlaştıkları için zemin davranışı basite indirgenip, zemin lineer elastik malzeme kabul edilmekte ve sadece elastisite modülü ve Poisson oranı gibi birkaç parametreye ihtiyaç duyulmaktadır. Gerçekte zemin davranışı lineer elastik olmadığı gibi çok karmaşık bir yapıya sahiptir. Bu çalışmada kum zeminler üzerine oturan dairesel temellerin taşıma kapasiteleri laboratuar ortamında küçük ölçekli model deneylerle ve sayısal analiz yöntemleriyle araştırılmıştır. Sonlu elemanlar yöntemine dayalı PLAXIS V.8.2 (Finite Element Code for Soil and Rock Analyses) bilgisayar yazılımı kullanılarak yapılan sayısal analizlerde Lineer Elastik, Mohr Coulomb ve Pekleşme Zemin modelleri kullanılmıştır. Sayısal analiz sonuçları model deney sonuçları ile karşılaştırılmıştır. Sonuçta deneysel verilerle Pekleşme Zemin modeli kullanılarak elde edilen sayısal verilerin birbirleri ile daha uyumlu olduğu gözlenmiş, kum zeminler üzerine oturan dairesel temellerin taşıma kapasitesinin hesabında Pekleşme Zemin modeli parametrelerinin kullanılmasının daha uygun olacağı kanaatine varılmıştır. Ayrıca, Pekleşme Zemin modelinde kullanılan çeşitli parametrelerin (içsel sürtünme açısı, rijitlik modülleri) zemin davranışına etkisi ile ilgili parametrik çalışmalar da yapılmış, sonuçlar yorumlanmaya çalışılmıştır.In soil-structure interaction problems, soil type, soil rigidity and soil deformation characteristics are important. Researchers commonly focused on structure behavior therefore soil behavior is simplified assuming soil as a linear elastic material and need a few parameters such as modulus of elasticity and Poisson’s ratio. In reality, soil behavior is not linear elastic, just the opposite, soil has a very complex structure. In this study, the bearing capacity of circular foundation rested on sandy soils was investigated by small scale model tests in laboratory and numerical analyses. Numerical analyses were performed with a finite element method based computer software program PLAXIS V.8.2 (Finite Element Code for Soil and Rock Analyses) and Linear Elastic, Mohr Coulomb and Hardening Soil models were applied in these numerical analyses. The results of numerical analyses and model test were compared. Eventually, it was observed that results from Hardening Soil model had good agreement with model test results and it was proposed that in sandy soil rested circular foundation’s bearing capacity calculation using Hardening Soil model parameters was most suitable. Additionally, a parametric study concerning with the effect of some Hardening Soil model parameters (friction angle, oedometer and triaxial rigidity modulus) on soil behavior was conducted and the results were discussed

Evaluation of Subgrade Modulus and Bearing Capacity with Large Scale Field Tests on Geogrid-Reinforced Granular Fill over Clay Soil

This study aims at experimentally explaining the potential benefits of geogrid reinforcedsoil foundations using large scale field tests. A total of 8 large scale field tests were carriedout to evaluate the effects of replacing natural clay soil with stronger granular fill layer andsingle-multiple layers of geogrid reinforcement placed into granular fill below circularfootings. The large scale field tests were performed using two different sizes of the circularfooting diameters which have 0.30 and 0.90m. The results of testing program are presented interms of subgrade modulus and bearing capacity. Subgrade modulus and bearing capacityvalues were calculated for each test at settlements of 10, 20 and 30mm.It has been seen that based on the test results, the use of granular fill and geogrid forreinforced soil foundations (RSF) have considerable effects on the subgrade modulus andbearing capacity

Prediction of bearing capacity of circular footings on soft clay stabilized with granular soil

AbstractThe shortage of available and suitable construction sites in city centres has led to the increased use of problematic areas, where the bearing capacity of the underlying deposits is very low. The reinforcement of these problematic soils with granular fill layers is one of the soil improvement techniques that are widely used. Problematic soil behaviour can be improved by totally or partially replacing the inadequate soils with layers of compacted granular fill. The study presented herein describes the use of artificial neural networks (ANNs), and the multi-linear regression model (MLR) to predict the bearing capacity of circular shallow footings supported by layers of compacted granular fill over natural clay soil. The data used in running the network models have been obtained from an extensive series of field tests, including large-scale footing diameters. The field tests were performed using seven different footing diameters, up to 0.90m, and three different granular fill layer thicknesses. The results indicate that the use of granular fill layers over natural clay soil has a considerable effect on the bearing capacity characteristics and that the ANN model serves as a simple and reliable tool for predicting the bearing capacity of circular footings in stabilized natural clay soil

Experimental and Numerical Studies of Square Footing on Weak Clay Stabilized with Geosynthetics-Reinforced Granular Replacement

This paper presents experimentally and numerically the bearing capacity and settlementcharacteristics of shallow footings rested on geogrid reinforced crushed limestone over weakclay soil. The effects of thickness of the crushed limestone, the depth and types of geogrid onbearing capacity and settlement characteristics of reinforced soil foundation (RSF) areinvestigated in laboratory, whereas numerical simulations are used to study the reinforcementfoundationinteraction. Test results indicate that the footing performance could be appreciablyimproved by the inclusion of layer of geogrid leading to an economic design of the footing.However, the efficiency of RSF system is dependent on reinforcement parameters. A closeagreement between the experimental and numerical trend lines is observed. Based on thenumerical and experimental results, critical values of geogrid parameters for maximumreinforcing effect are established

Bočna nosilnost kratkih togih pilotov v dvoslojnih nevezljivih tleh

The behavior of a laterally loaded short rigid pile founded in a two-layer sand soil profile has been investigated. For this purpose, a series of model tests were carried out on model piles. The effects of the elasticity modulus, dilatancy and interface behavior of the sand have been explored numerically by performing a series of three-dimensional non-linear finite-element analyses. The lateral load capacities in the layered sand conditions have been calculated using the methods proposed by Brinch Hansen (1961) and Meyerhof et al. (1981). The results obtained from experimental studies, numerical analyses and a conventional method were compared with each other. The results proved that the parameters investigated had a considerable effect on the behavior of short rigid piles subjected to lateral loads. It was also shown that the value of the ultimate lateral load capacity could vary significantly, depending on the methods used.V članku je predstavljena raziskava bočno obteženih kratkih pilotov v dvoslojnih peskih. Za ta namen je bil izveden niz modelnih preizkusov na modelih pilotov. Z izvedbo niza tridimenzionalnih nelinearnih analiz s končnimi elementi so bili raziskani učinki elastičnega modula, dilatacije in interakcije peska in pilota. Bočne nosilnosti pilotov v pogojih slojevitih peščenih tal so bile izračunane z metodami Brinch Hansen (1961) ter Meyerhof idr. (1981). Med seboj so bili primerjani rezultati dobljeni z eksperimentalnimi študijami, numeričnimi analizami in konvencionalno metodo. Rezultati so pokazali, da imajo preiskovani parametri precejšen učinek na obnašanje bočno obteženih kratkih togih pilotov. Prikazano je tudi, da vrednost mejne bočne nosilnosti pomembno varira glede na uporabljeno metodo

A Modern Approach to Estimate the Bearing Capacity of Layered Soil

This study is concerned with the bearing capacity of circularfootings on a granular fill layer above a soft clay soil. Theresults of an extensive series of laboratory and field tests wereused to define an empirical equation. This is generally doneby estimating the dependent variable (e.g. bearing capacity)based on the independent variables (e.g. granular fill layerthickness, soil and footing parameters and settlement ratio).A logarithmic model has been developed by using regressionanalysis to estimate the bearing capacity of a circular footingresting on granular fill at any settlement ratio, using allpossible regression techniques based on 342 field test data, toselect the significant subset of the predictors. The results indicatethat the logarithmic model serves a simple and reliabletool to predict the bearing capacity of circular footings placedon a granular fill with different thicknesses above a soft claysoil. And also, the validity of the developed formulation wasverified with different plate load test results from literature