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Herein, an experimental investigation of the plugging impact on the capacity of open-ended piles installed in clayey soil is presented. Model tests involving static axial compression load tests are carried out on four open-ended modeled piles with different diameters (12.5, 19, 25, and 50 mm). In the same manner, four closed-ended modeled piles are tested to make a comparison. A load cell system is used to determine the resistance acting on the piles, with an instrumented transducer on the outside walls of the pile. The eight steel model piles are tested in the circular steel tank with a diameter of 350 mm and 400 mm in length. Three undrained shear strengths of the clay sample, 5 KPa, 10 kPa, and 18 kPa, are used in model tests. The outcomes of the tested models uncover that the pipe pile capacity is mainly mobilized at the low shear strength. In addition, it is realized that the soil plugging in the small diameter has an impact on pipe pile capacity. Based on experimental results, five statistical models are established to achieve relations between the maximum load for the closed-ended pipe. It is realized that the value of Qexp is highly correlated with the diameter and Qcalc..

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The deep method (DMM) is a soil remediation method that involves on-site mixing of soil with cement and/or other materials. These compounds, which are also known as "bonding materials," can be applied dry or wet. The current study involves the construction of 13 laboratory models to examine the means of improving soft clay soil qualities through deep mixing techniques with piling foundation. In the dry condition, static loading studies on piles and DMM were carried out using tow materials, cement, and lime. The model experiments included a single pile as well as groups of piles and cement or lime columns. There were two, three, and four piles or columns in each group. The model tests revealed that deep mixing had a significant impact on increasing bearing capacity by averaged times ranging from 1.23 to 2.43 times for soft clay soil treated with single and groups of four cement or lime columns, respectively, as well as minimizing settlement by averaged percentages ranging from 33% to 89 percent. These results were comparable to those obtained using pile foundations in the same manner. The outcomes of the model tests were also evaluated in terms of group efficiency.

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The emphasis of current work is on assessing the settlement improvement ratio, which is described as the ratio between the settled soils treated with a stone column and the settlement of the non-treated soil (Sr = Streated/Suntreated). The research was conducted using a 300 mm diameter and 300 mm high stone-column container testing model. On 14 modeled stone columns made only from crush stones and using various backfill content, model tests including static axial compression tests were performed. The substance used in the stone backfill column had been changed by sand or lime or cement percentages. The shear strength prepared by the containers varied between 5.5 kPa and 13.5 kPa. Results show that the settlement ratio values, Sr achieved with crush stone, crushed stone +50% sand, crushed stone +5% dry lime, crushed stones +10% dry lime, crushed stone +2.5% cement +5.0% crushed stone +5.0% cement, respectively, was 0.23, 0.12, 0.16, 0.15 and 0.09. In other words, there is a drop in the settlement from 77% to 91%

ملخص البحث :

Abstract. This study used a finite element analysis approach employing Plaxis 3D to analyze the stress concentration ratio, a critical parameter in geotechnical engineering, to examine stresses operating on stone columns and soft soils. This study also looked at the effect of the stiffness ratio between the stone column and the neighboring soil. With the same length and three different diameters, 0.8 m, 1.0 m, and 1.2 m, or three area replacement ratios ranging from 7% to 16%, respectively, floating and end-bearing stone columns were used. The influence of soft soil undrained cohesion, cu ranging from 6 kPa to 40 kPa, was also considered in the current study. The stiffness ratio for columns to adjacent soil, end bearing or floating stone column, and area ratio all have a significant impression on the performance of the stone column in treating soft soil and stress transmission mechanisms in the enhanced soil body, according to parametric studies. The average stress concentration ratio in soil improved with an end-bearing stone column of φ= 35o and raised to 2.63 and 4.71 at φ = 50o, ranging from 1.41 to 2.35 for area replacement ratios of 7% and 16%.