Soil arching and load transfer mechanism for slope stabilized with piles

In this study, the effects of pile spacing and pile head fixity on the moment and lateral soil pressure distribution along slope stabilizing piles are investigated. A slice from an infinitely long row of piles with fixed pile tip in an inclined sand bed was simulated with an experimental test setup. Surficial soil displacements were monitored and relative displacements between soil particles were determined by recording time-lapse images during the test in order to observe the soil arching mechanism on the soil surface. The load transfer process from moving soil to piles and behavior of soil around piles were observed and evaluated by the different test setups. It was observed that decrease in pile spacing causes an increase of load carried per pile. This behavior, which was significantly influenced by the pile head boundary conditions, can only be explained by soil arching that existed between the piles along their lengths

Development of a Computerized Measurement System for in-Row Seed Spacing Accuracy

WOS: 000266361100001The aim of this study was to develop a computerized measurement system (CMS) combined with a sticky belt test stand for examining in-row seed spacing distribution accuracy. For this purpose 8 performance parameters were selected for precision seeding: mean seed spacing, the standard deviation, the multiples index, the miss index, the quality of feed index, the precision, the population index. and the coefficient of precision (CP-3). The CMS hardware consisted of a high precision optical mouse coupled with a laser pointer and a notebook computer. The use of optical laser technology is a new method for the determination of seed spacing distribution. The CMS stored seed coordinate data, which was input using a simple user interface, and sent to the data to Microsoft Excel for further statistical analysis. The results obtained from this study confirm that the combination of a sticky belt test stand and CMS can be used instead of a digital caliper and steel tape measure to rapidly and correctly obtain quantitative evaluations of seed spacing uniformity in the laboratory

Lime Stabilization of Soils Underlying a Salt Evaporation Pond: A Laboratory Study

The purpose of this article is to investigate a possible use of lime for the stabilization of base soils underlying salt evaporation ponds in camalti Solar Marine Salt Plant. The plant is located on the old Gediz River Delta, on the north shore of the Izmir Bay-Turkey, where alluvial deltaic soft marine sediments constitute the local soil condition. The low bearing capacity of the pond base soils results in some problems on the mechanical harvest of the solar salt. Therefore, stabilization was taken into consideration for improving the productivity of the salt plant. For this purpose, bench-scale laboratory tests were performed on the specimens that had been sampled from the bases of the salt evaporation pond to investigate the influence of lime on the unconfined compressive strength (UCS) of these marine sediments. By interpreting the pH test results and consistency limits of the lime stabilized soils, optimum lime content was determined as 8%. The verification of the long-term pozzolanic reactions for the optimum lime content was conducted by performing UCS tests with up to six months curing periods, along with the microstructural analysis through X-ray diffraction analysis (XRD) and a scanning electron microscope (SEM). Long-term tests revealed that the optimum lime content successfully sustained the required pozzolanic reactions, and a strength gain of 500% was achieved for a six-month curing period

A Visual Basic program for analyzing oedometer test results and evaluating intergranular void ratio

A visual basic program (POCI) is proposed and explained in order to analyze oedometer test results. Oedometer test results have vital importance from geotechnical point of view, since settlement requirements usually control the design of foundations. The software POCI is developed in order perform the necessary calculations for convential oedometer test. The change of global void ratio and stress-strain characteristics can be observed both numerically and graphically. It enables the users to calculate some parameters such as coefficient of consolidation, compression index, recompression index, and preconsolidation pressure depending on the type and stress history of the soil. Moreover, it adopts the concept of intergranular void ratio which may be important especially in the compression behavior of sandy soils. POCI shows the variation of intergranular void ratio and also enables the users to calculate granular compression index. (C) 2005 Elsevier Ltd. All rights reserved

Predicting Uniaxial Compressive Strengths of Brecciated Rock Specimens using Neural Networks and Different Learning Models

Calculation of the Uniaxial Compressive Strength (UCS) of Breccia Rock Specimens (BRS) is required for the correct determination of material strengths of marble specimens. However, this procedure is expensive and difficult since Destructive Laboratory Tests (DLT) are needed to be done. Therefore, the results of Non-Destructive Laboratory Tests (NDLT) combined with different features that are extracted by using image processing techniques can be used instead of DLT to predict UCS of BRS. The goal of this study is to predict the results of DLT by using the results of NDLT, extracted features and Artificial Neural Networks (ANN). Unfortunately, having enough number of specimens for training of ANN is often impossible since the preparation of the standard BRS is extraordinarily difficult. Hence, it is very important to use a learning methodology that prevents deficient evaluation practices. Therefore, different well-known learning methodologies are tested to train the ANN. Then, their effects on error estimation for our small size sample set of BRS are evaluated. The results of simulations show the importance of learning strategies for accurate evaluation of an ANN with a low error rate in prediction of UCS of BRS

Nondestructive evaluation of volumetric shrinkage of compacted mixtures using digital image analysis

Adapting image processing technology to engineering disciplines can be useful in the evaluation of the mechanical behavior of materials. Not only characteristics of granular materials, but also particulate levels of colloids can be studied using image analysis. Attempts to identify the volume change of soils or compacted specimens have been made since late 1990s. Some of the previous studies were related with the determination of the deformation field during triaxial tests while the rest were directly related with the measurement of the volumetric shrinkage strains of expansive soils. Unlike with other studies, considered volumetric shrinkage strain levels in this study were limited to 6%. The strain levels were limited, because it was noted that the maximum allowable volumetric shrinkage strain levels were 5% for evaluating the hydraulic behavior of compacted soils. The principal purpose of this study is to show the ability of image processing techniques on the quantification of the volumetric shrinkage of the compacted soils even in the small strain levels. For this purpose, a special test setup was established and a computer algorithm was developed to identify volume of the specimens from digitized images. Initially, volume changes of compacted bentonite-zeolite mixtures at various bentonite contents were measured by means of vernier caliper. Comparison of the digital measurement results with those of the manual readings showed that they were in good agreement. It appears that the proposed methodology would provide nondestructive, stable and repeatable volume measurements and is a promising approach for the quantification of volumetric shrinkage strains of compacted bentonite-zeolite mixtures even at small strain levels. (c) 2006 Elsevier B.V. All rights reserved

Factors Affecting Complication Rates of Percutaneous Nephrolithotomy in Children: Results of a Multi-Institutional Retrospective Analysis by the Turkish Pediatric Urology Society

WOS: 000331123400081PubMed ID: 24095906Purpose: We assessed factors affecting complication rates of percutaneous nephrolithotomy in children. Materials and Methods: We retrospectively evaluated data on 1,205 renal units in 1,157 children treated with percutaneous nephrolithotomy at 16 Turkish centers between 1991 and 2012. Of the patients 28.3% had a history of urolithiasis. Complications were evaluated according to the Satava classification system and modified Clavien grading system. Univariate and multivariate analyses were done to determine predictive factors affecting complication rates. Results: A total of 515 females and 642 males were studied. Mean +/- SD patient age was 8.8 +/- 4.7 years (range 4 months to 17 years). Mean +/- SD stone size, operative time and postoperative hospital stay were 4.09 +/- 4.06 cm 2, 93.5 +/- 48.6 minutes and 5.1 +/- 3.3 days, respectively. Postoperative stone-free rate was 81.6%. A total of 359 complications occurred in 334 renal units (27.7%). Complications were intraoperative in 118 cases and postoperative in 241. While univariate analysis revealed that stone history, positive urine culture, operative time, length of hospitalization, treatment success, punctured calyx and location of the stone significantly affected the complication rates (p <0.05), operative time, sheath size, mid calyceal puncture and partial staghorn formation were the statistically significant parameters affecting complication rates on multivariate logistic regression analysis. Conclusions: Percutaneous nephrolithotomy is the treatment of choice for most renal calculi in children. The technique is effective and safe in children, with a high success rate and a low rate of major complications. The significant factors identified should be considered by clinicians to decrease associated complication rates

Factors Affecting Complication Rates of Percutaneous Nephrolithotomy in Children: Results of a Multi-Institutional Retrospective Analysis by the Turkish Pediatric Urology Society

Purpose: We assessed factors affecting complication rates of percutaneous nephrolithotomy in children