Study on the Increase of the Supporting Capacity of a Cement Milk Pile with Expansive Additives

In this study, an engineering characteristic test was conducted on cement milk using expansive additives during the construction of bored piles. Expansive additive mixtures with various mixing ratios were prepared according to the construction standards of the Korea Expressway Corporation. Segregation resistance, compressive strength, frictional resistance stress, scanning electron microscope images, porosity, and economic feasibility were analyzed. It was found that segregation effects due to expansive additive incorporation were insignificant, and it was confirmed that all specimens exceeded 0.5 N/mm2, the compressive strength standard of the Korea Expressway Corporation pile bearing capacity. Given a water–binder ratio of 83% mixed with 10% expansive additives, frictional resistance increased up to ~35%, skin friction force was significantly improved, and a cost-saving effect of up to ~33.24% was achieved.

Performance Improvement Study of Linear Photovoltaic Systems With Concentration of Solar Radiation

A new type of linear cooled photodetectors is considered, of which in the focal region of the optical concentrator mirrors is installed an array of solar cells operating with the low-ratio solar concentration. This work is focused on the theoretical and experimental substantiation of the efficiency increase of photodetectors under conditions of an optimal combination between solar radiation concentration and heat transfer intensity of photovoltaic cells with heat carriers. The problem of obtaining a high temperature liquid due to the limitations of solar cells is solved by organizing the flow of fluid within the thermal collector channels in the focal region of an additional optical concentrator. A mathematical model of engineering characteristic calculation of the Ʌ - shaped photodetectors and cost calculation of electrical and thermal energy generation is presented. The research results are used in the development of industrial prototypes of photodetectors with a concentration of solar radiation and low production costs.

Characteristics of Palangkaraya fibrous peat

Palangkaraya fibrous peat soil is a soil with high organic content and was formed due to decomposition of plants in submerged areas for long periods. In the tropics, peat has a high fiber content that affects the physical and engineering characteristic and have different behavior with clay. Laboratory and field tests were conducted to determine the physical and engineering characteristic of fibrous peat and to compare it with clay. The results of the tests on fibrous peat show peat soil parameter very different from clays. The unit weight of peat is 1.04 gr/cm3 with specific gravity is 1.4 and water content reach 650%. This physical parameter shows that peat is a very soft soil that is dominated by water in its structure. Organic content of peat reached 97% with a very low ash content of 3%. This behavior indicates that the decomposition of plants causes physical properties of peat that are very different from clays. The bearing capacity of the peat is also very low. The shear strength was about 26.8 kPa (ov = 50 kPa) and was dependent on the fiber distribution in the sample under test. Vane shear test results also show the same thing that is 5-7 kPa. The very different behavior of fibrous peat with clay is the consolidation. Peat has 4 stages of compression wherein secondary compression is the main compression. This behavior is due to the fibrous peat has two pores, that are micropores and macropores. The results of comparisons can serve as a basis for determining appropriate peat soil improvement methods.

Plasticity Behaviour of Sand Matrix Soils

Natural sand does always contain significant amounts of fine particles, but previous study always assumes that the typical engineering characteristic of clean sand was remarkably representing as to all types of sand matrix soils. Studies reported that additional of plastic fines could either impose additional or reduce the liquefaction resistance of sand matrix soils. Therefore, the aim of this paper is to examine the plasticity behaviour of sand matrix soils through experimental study. The Atterberg Limit test was carried out on plastic fines mixtures and sand matrix soils. Results show that the plasticity behaviour is depending on the type of presenting plastic fines. The absorption of clay mineral is the key element to in manipulating the plasticity behaviour of plastic fines. It can be concluded that the absorption of montmorillonite is better compare to kaolinite.

Analysis of Deformation Bands in Polyurethane Foams

Closed cell polyurethane foams with densities of 100, 160 and 301 kg/m3 were tested in compression at speeds of 1 and 5 mm/min. Digital image correlation (DIC) is used to determine the engineering characteristic curve, modulus of elasticity, Poisson's ratio and the deformation bands that appear during deformation and prior to the final failure of the specimens. By using this procedure both global and local phenomena are observed and analyzed. While each specimen is compressed the damage behaviour of the foams is directly observed in different stages, as being in the linear elastic domain, in the plateau region, and in the densification region. Several observations, characteristic for each foam density are discussed. As damage mechanisms are different, DIC allows the direct monitoring of the formation of the deformation bands and their propagation till the final failure of the foams, as long as calculations of the local strains are possible. Maps of the vertical displacements and local Mises strains are presented and comments on the characteristics of the deformation bands are done.

Testing Study on Rock-Like Materials under Water Pressure Conditions

According to test exploration and research, the authors developed a multiaxial compression testing machine and water injection pressure device. Using the device, the authors carried out a multiaxial compression testing of transparent rock-like material successfully under water pressure condition. It has important meanings to the study on the engineering characteristic of fractured rock under pressurized water conditions.

Research on Nanning No.1 Subway Strata Combination Model and Regionalization

Analyzing and summing up the engineering geological and hydrogeological features of Nanning No.1 6 Subway, types strata combination model are put forward, which combing the first exploration data. Then the URT Line 1 is divided into 5 kinds engineering geology partition. At the same time, all engineering geology partitions engineering characteristic and engineering problem possibly appears are analyzed, drawing a conclusion that these first three types partitions shield tunnel may have more problem in the process of construction.