Shear Strength Properties of Organic Soil with Sand Column

This paper discusses the results of a series of direct shear test that were undertaken toinvestigate the behaviour of organic soil with granular soil column. The tests focused oneffect of diameter of granular column in organic soil. Water content of the organic soil waskept constant for all tests. It was 125% that is liquid limit value. Four different column diameters were used. Sand used in the test is poorly graded and passing the No. 5 sieve andretaining on sieve No. 40 sieve. Shear strength properties of the samples were determinedfrom direct shear test. Loading was performed under undrained condition. Test results showed that ratio of sand column area to organic soil (S/O) are an important factor effecting shear strength properties of improved organic soil

An Investigation of Geomechanical and Microstructural Properties of Full-Scale Jet Grout Column Constructed in Organic Soil

Jet grouting methods have recently become one of the soil enhancement technologies utilized to provide strength improvement and solve most problems of weak soils. In this study, a full-scale 1 m diameter and 5 m length jet grout (soilcrete) column was constructed in the field with a water-to-cement ratio of 1 and 400 bar pressure injections. A mechanical, physical, and microstructural investigation was performed on jet grout samples taken from six different depths (0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 m) and at the same depth at five different locations, including the center. For normal conditions, samples were prepared for six periods to study dry and saturated conditions. The following tests are performed on each sample: compressive strength index (I-s) in all conditions, water absorption, density, porosity, and interface friction. Additionally, SEM was performed on selected samples to investigate the microstructures of jet grout columns (JGCs). The test results showed that the I-s varies with depth, and within the same depth, the variation is approximately 20%. Other properties also vary with depth and location; for example, the average percentage of water absorption and porosity are considered minimum values at the same location, which are 53 and 30%, respectively. However, the interface friction angle of organic soil-cement grout gains 48 degrees and 10 kPa cohesion. The theoretical part of this study is to predict the diameter of JGC in organic soil

A Study About Effect Of Soil Model On Slope Under Vibration Load

This paper presents the effect of soil material model on slope under vibration loading. Ahard consistency clay is assumed within an example slope profile with the height of 10m andangle 25 for the evaluations. The linear elastic, Mohr-Coulomb and hardening soil modelsare considered using 2D finite element method by dynamic analysis. The results indicate that the velocities evaluated by the soil models are within the safety limits and accepted for the design. The soil models almost perform same values for factor of safety (not for linear elastic)and velocities. This study is believed to be beneficial for the applications in practice

Stabilization of Clay with Waste Soda Lime Glass Powder

AbstractThis study was carried out with an intention to observe any sign of improvement of clayey soil due to addition of waste soda lime glass powder (WSLGP). Waste soda lime glasses were crushed and sieved through #200 (75μm) sieve and mixed with clay in 3, 6, 9, and 12% in dry weight of the clay. Strength and consistency test were carried out on mixed samples after curing. The test results indicated that the addition of WSLGP into clay has a significant effect on the strength and consistency properties of the clay

Interface Friction Between Organic Soil and Construction Materials

In this study, interface frictional resistance between organic soil and some of construction material was investigated. Construction materials used in this work are concrete,metal, and wood. Interface friction angle were determined for three different water contents values of organic soil dry, 25%, 50%, and 75% respectively. Different face roughnesses were tested for different water content. All tests were carried out using direct shear test device.Three different normal forces were used and shear stress at 10% strain rate was taken as maximum shear stress. Test results showed that water content of the organic soil, material type, and surface roughness should be considered while selecting interface friction angle between organic soil and construction materials

Effect of glass powder on the rheological and mechanical properties of slag-based mechanochemical activation geopolymer grout

This article discusses the effects of glass powder (GP) replacements and sodium hydroxide (NaOH) molarity on the rheological, fresh, mechanical and microstructure characteristics of slag-based mechanochemical geopolymer (MG) grout. A conventionally activated geopolymer grout and an ordinary Portland cement (OPC) grout were also investigated for comparison. Four glass powder replacement ratios were used (0%, 10%, 20% and 30% by the total precursor weight) to prepare slag-based mechanochemical geopolymer at three NaOH concentrations (1.25, 2.5 and 3.75 molars). The experimental results showed that the rheological behaviour of MG grouts was considerably reduced, whereas the setting time and the bleeding capacity value increased when slag was substituted with 0%–30% GP. However, after 28 days, the unconfined compressive strength (UCS) improved by 2%–13% when 10%–20% GP was used as a slag replacement, then dropped by 4% when 30% GP was substituted. The results confirmed that both geopolymer grouts irrespective of the activation method had shorter setting time and more stable bleeding capacity than OPC grout. The results also revealed that the UCS of geopolymer grout is enhanced by 18% when the source materials are activated by the mechanochemical method compared to the conventional activation of geopolymer grout. The microstructure results revealed that the activation method had a considerable effect on the microstructure of geopolymer grout because the ball milling process increased the surface area and reduced the particle size of slag compared to conventionally activated geopolymer grout. © 2022 Informa UK Limited, trading as Taylor & Francis Group

Collapse of caves at shallow depth in Gaziantep city center, Turkey: a case study

This paper focuses on an investigation of the possible causes for the collapse of limestone caves in Gaziantep, Turkey. The city contains a lot of man-made caves, at a shallow depth, of various width and length. These caves were mainly excavated to provide work or storage space. As the city has been growing fast with increased population, many structures were constructed over these caves. Recently, two caves collapsed and five houses were damaged. These caves are all made of limestone and it was observed after the collapse that the limestone was saturated with water due to sewer pipe leakage and surface water. Tests were carried out on the limestone and it was determined that the compressive strength of limestone decreases by about 50% and the tensile strength decreased by about 80% when saturated with water. It was concluded that the reduced strength of the limestone combined with additional loads due to the factors mentioned above seem to be the main reason for these collapses

Physical-mechanical assessment of full-scale soil-cement column constructed in clayey soil

Jet grouting has recently become a soil improvement method used to solve most soil problems. In this study, seven full-scale soil-cement (SC) columns were constructed in clayey soil with different pressure injections (300, 325, 350, 375, 400 bar), jet grout rotations (25, 35, 45 rpm) and a w/c ratio of 1. These parameters were used to examine the geomechanical properties of the SC, such as strength characteristics (UCS and UPV), and SC-soil surface friction. The physical properties were observed by evaluating the water absorption rate, density, and porosity. The diameter variation was analysed to determine the effect of both parameters on SC diameter. The geomechanical properties of the grout columns generally varied with pressure and rotation. The average strength variation for pressure and rotation was 38% and 9%, respectively. The average water a

Assessing the Effect of Seawater and Magnesium Sulfate on the Durability and Strength Properties of Cement-Stabilized Full-Scale Soilcrete Column Constructed in Clayey Soil

Jet grouting techniques have lately become one of the soil enhancement technologies used to increase the strength of poor soils and resolve most of their difficulties. Seven full-scale soilcrete columns (SC) were formed in clayey soil using a one-to-one water-to-cement ratio and different parameters, including five different pressures (30, 32.5, 35, 37.5, and 40 MPa) and three different rotating rates (25, 35, 45 rpm). These metrics were used to assess SC's resistance to chemical attacks [seawater, magnesium sulfate (MgSO4)]. Additionally, it is also working on the strength investigation (unconfined compression test) of samples after 105 days of curing in chemical solutions. Scanning electron microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX) were used to study the microstructural behavior and chemical element distribution of full-scale SCs. As a result, chemical attacks significantly affected upon the SC samples regarding pressure injection and jet grout's rotation parameters. In detail, the seawater solution positively impacted on the strength characteristic of SC specimens compared with the normal environment, which is the average strength has been increased 20%. While, considerable deterioration and deformation were detected in MgSO4 solution, leading to losing the mass and decreasing the strength for both parameters, ranging between -10.2% and -58.8% for mass change and 2.0 and 9.5 MPa for strength, at 105 days curing. SEM and EDX images proved the chemical attacked deteriorations and generation of hydration product with pozzolanic reactions

Zemin Sıkışma İndeksi için Korelasyonların Geliştirilmesi

Compression index is one of the most important properties of soils widely used for estimation of settlement during design of foundations. In particular, for routine test requirements, limited laboratory facilities and preliminary evaluations, various equations are available in the literature to simply estimate the compression index using some soil index properties. However, applicability of these equations is often limited for the interested site due to their establishment from different databases. Thus, it is more realistic way to employ the correlations developed using local data of region, provided that data is available. In this viewpoint, this paper aims to develop correlations for the compression index dependent upon the soil index parameters of natural moisture content, liquid limit and initial void ratio for fine‐grained soil of Baghdad city. From the developed correlations, it is obtained that the best estimations of compression index is correlated by liquid limit as single variable, and by liquid limit and initial void ratio as double variable. It is clear that use of the developed correlations is more suitable specifically for Baghdad region for preliminary evaluations of foundation settlementSıkışma indeksi, temellerin tasarımında oturma hesapları için yaygın olarak kullanılan zeminlerin en önemli özelliklerinden biridir. Özellikle rutin deneyler, sınırlı laboratuvar koşulları ve ön değerlendirmeler için, literatürde zemin indeks özelliklerine bağlı olarak basitçe hesaplanabilen sıkışma indeksi denklemleri mevcuttur. Ancak, bu denklemler değişik verilerden oluşturulduğundan, çoğunlukla ilgilenilen bölge için sınırlı kullanım sunmaktadır. Bu yüzden, bölgeye ait yerel veriler ile (eğer veri mevcutsa) geliştirilen korelasyonları kullanmak en gerçekçi yoldur. Bu doğrultuda, bu çalışmada Bağdat şehrine ait ince daneli zeminler için, zemin indeks özelliklerinden doğal su muhtevası, likit limit ve başlangıç boşluk oranına bağlı olarak sıkışma indeksi denklemlerinin geliştirilmesi amaçlanmıştır. Elde edilen denklemlerden, sıkışma indeksinin tek değişkenli ilişkilerde likit limit ile, ve çok değişkenli ilişkilerde ise likit limit ve başlangıç boşluk oranı ile birlikte kullanıldığında en iyi korelasyonları verdiği bulunmuştır. Geliştirilen korelasyonların temel oturması için yapılacak ön değerlendirmelerde özellikle Bağdat bölgesi için kullanılmasının çok daha uygun olduğu açıktır.