Collapsible soils are among the problematic soils in nature that due to wetting, make many settlements so that according to research, the amount of settling can reach 1 to 2% of the thickness of the soil layer.If this type of soil is not identified, if structures are built on them, the constructed structure will be damaged if the soil saturates and changes in soil moisture. The existence of such soils in many parts of the world including Kerman province of Iran, necessitates the attention to study the behavior and characteristics of the collapsible soils. The aim of this contribution is to investigate the effect of butadiene rubber on the stabilization of collapsible soils. The tested fine-grained soils that have been sampled from two different sites were stabilized through injecting different percentages of butadiene (the number of experiments was 84). The ASTM D5333 Double-Consolidation Method, was applied in order to examine the stabilized soils on intact soil samples. The results show that the penetrations of butadiene rubber as well as the formation of butadiene rubber columns have led to reduction in soil collapse. Considering development of intelligent systems using prediction behavior of stabilized collapsible soils, the ANFIS model was used to predict degree of collapsibility of soil samples stabilized by injection Styrene Butadiene Rubber.

The aim of this study was to improve the characteristics of natural collapsible soils using the geogrid-encased stone column technique. For this purpose, 20 large-scale specimens of stone columns were prepared using rigid metal cylinders with a diameter of 308 mm and a height of 97 to 154 mm according to the unit cell theory. The aspect ratio was 10% to 25%. For the occurrence of bulging failure, the height of the stone columns was considered six times the diameter. The stone columns were encased with geogrids of varying stiffness from 80 to 200 kN/m. The soil around the stone column inside the unit cell was compacted to similar site conditions. Loading was applied similar to the test, which determines the soil collapsibility potential while the specimens were being inundated from the bottom of the metal cylinder by a water feeding system. During loading, the vertical displacements of the stone columns were measured at two locations on the loading plate. The results showed that the columns settlement due to inundation diminished by increasing the stiffness of the encased stone columns and aspect ratio. The optimum aspect ratio was approximately 15%. Encasement of the stone columns increased the lateral pressure in the collapsible soil and prevented the collapse of the stone column. The settlement values of stone columns were compared with a settlement prediction model and showed a good agreement. The data obtained in this study can be used as a practical method to improve natural collapsible soils during inundation.

Collapsible soil is defined as loose deposit with a metastable and porous structure and mostly is found in arid and deserted regions. The particles of soil in the unsaturated state are connected together by capillary tension and in the dry state by cementation such as clay and silt bond or by other cohesive material like calcium silicate. The cementation agent makes a relatively high apparent strength in this type of soils but it will collapse in wet condition due to weakening effect of moisture. As city of Semnan is located in a dry area with collapsible soil in some parts of its urban district. It is highly endangered by this natural phenomenon. Therefore further studies on recognition and developing method of dealing with this phenomenon is really important. This study investigated the effect of bentonite, microsilica and rice husk ash on soil volume change has been studied. Based on test results on stabilized samples, by adding microsilica up to 4% of total weight of soil sample will reduce collapse potential, but increasing percentage of microsilica will have opposite effect. In addition by adding a mixture of additives consists of fixed portion of 3% of microsilica and variation portion of bentonite as well as by adding rice husk ash the results show that collapse potential had been reduced continuously.

There are some kinds of soils in nature which show a significant decrease in volume by increasing the humidity percentage under a fixed pressure. these solis are called collapsible soils. Collapsible soil shows a noticeable decrease in its volume with an increase in its moisture content under fixed stress. This decrease in volume causes irreversible damages to any structures on collapsible soil and the ones which are under construction. The study of the behavioral characteristics of collapsible soil and its stabilization is crucial. The main purpose of this study is stabilizing collapsible soil and increasing shear strength by adding E.M. Super Repair with different combinations. A sample was collected from Hamidiyeh region near Ahvaz. The primary geotechnical tests were done on the sample. Then shear strength parameters were determined by adding E.M. Super Repair with different combinations. The results show this substance improve the shear strength parameters. The most shear strength has been observed in 1% combination.

Weakness of soil in bearing capacity, lack of desirable mechanical properties, swelling properties, etc. These issues and methods required new tricks that were achieved with the evolution of engineering knowledge and the emergence of new technologies in the field of civil engineering. Different methods for soil improvement are selected according to the importance of the project, primary soil type, area of the area to be improved, local access to materials, equipment and specialized personnel, environmental factors, engineers' experiences, economic issues and time allowed to complete the project. To be. It should be noted that knowing the area and studying the types of soils that cause problems is also very necessary and important. In many cases, the soil at the construction site is not suitable for use. In this situation, this problem can be solved with appropriate solutions. One of these solutions is chemical stabilization of soil. Chemical stabilizers stabilize and strengthen soil by creating chemical reactions and altering the structure and bonding between soil particles. In this type of reaction, soil particles completely lose their nature and become a substance with new characteristics. In this article, first, in addition to getting acquainted with the types of problematic soils, the most important methods of soil stabilization and soil formation and various methods of chemical soil stabilization are examined.

Background and Aim: In clinical practice it is commonly assumed that occlusal splints have therapeutic value in the treatment of temporomandibular disorders (TMD), however there is still lack of sufficient evidence to support this claim. The purpose of this double-blind study was to evaluate the short-term (8-week) efficacy of a stabilization splint in subjects with temporomandibular disorders seeking treatment.Materials and Methods: Seventeen TMD patients were treated with stabilization splints for eight weeks. In addition to filling out questionnaires, all patients underwent a preoperative and postoperative clinical-functional investigation of the masticatory system. Qualitative data were analyzed using Fisher exact and Chi-square tests and Wilcoxon signed ranks test was applied to report quantitative data.Results: A statistically significant decrease was observed postoperatively in the Helkimo clinical dysfunction index (P=0.000) as well as the anamnestic dysfunction index (P=0.020). In addition there was a statistically significant decrease in muscle tenderness, after treatment (P=.002).Conclusion: The results of this study indicate that the use of a stabilization splint is beneficial in treatment of the signs and symptoms of TMD, and especially has a positive effect on muscle tenderness.

The main aim of this experimental analysis is to understand the effectiveness of ceramic waste (CW) in stabilizing the clayey soil. The effect of adding various CW percentages (5%, 10%, 15%, 20%, 25%, and 30%) on the geotechnical properties of clayey soil is evaluated by performing a series of laboratory tests like the Atterberg’s limit test, compaction test, unconfined compressive strength (UCS) test, California bearing ratio (CBR) test, and swelling pressure test. Micro-structural analysis including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform-infrared (FT-IR) spectroscopy are carried out on untreated and treated clay-ceramic composites. The results obtained indicate that the incorporation of 30% ceramic waste in clay soil increase the maximum dry unit weight (γmax) from 17.20 kN/m3 (CL + 0% CW) to 18.25 kN/m3 (CL + 30% CW). The unconfined compressive strength of clayey soil increases with the addition of ceramic waste. A maximum UCS of 217 kPa is obtained with 25% ceramic content, beyond which it starts decreasing. Similarly, increasing trend in CBR results is observed with an increase in the ceramic waste content. The increment in CBR is approximately 152% (unsoaked condition) and 142% (soaked condition). At the same time, the addition of ceramic waste in clay soil reduces the Atterberg limits, optimum water content (ωopt), and swelling pressure. “It can be concluded from the experimental study that CW can be used as a sustainable alternative soil stabilizer.

Sand and clay soils are the most usually common soils that constitute the subgrade of roads in northern parts of Iran. The clay soil has high plasticity index. Also they have high strength in dry condition, in saturated state, they lose most of strength and during this time, sustain much swelling which is dangerous for pavement. Sandy soils in coastal zones are termed Beach sand and have considerable strength in confined state. However In unconfined state, because of their uniform gradation and lack of cohesion, they will be washed out by water flow. In this research, the effects of Waterproof cement on engineering properties of these soils compared to Type 2 cement and Lime have been considered. In order to investigate the effects of the above materials on improving soil properties, Atterberg limit, Unconfined Compressive Strength and CBR tests have been carried out. It was found that the Waterproof cement has superior effect on strength properties of soils compared to the two other additives. The tests have also shown the average effect of this additive on the Plastic properties of soils.

In many parts of the world, the formations of sinkholes are reported by many researches. In the past few years. several sinkholes have formed in the northern part of Hamedan, between Hamedan and Famenin cities. The geotechnical results evaluation indicates that collapsible sandy soil and Karstic bedrock contribute to the formation of those sinkholes. It is understood that the simultaneous role of those factors significantly affects the size of sinkholes. In the previous researches, the mutual role of solubility of bonding material and the presence of collapsible sandy soil are not taken into account. In the current research with consideration of this point, a series of odometer testing performed. The artificially added sodium sulfate, sodium carbonate, and carbonate calcium made possible to consider the effect of chemical bonding on the behaviour of collapsible sandy soils. It is shown that the collapsible behaviour of sandy soil having calcium carbonate as its bonding material is very sensitive to the pH of soil pore water. It is concluded that in the area susceptible to collapsible behaviour, the presence of soluble bonding may significantly affect the size and development of sinkholes.