Papers by Keyword: Triaxial Test

Abstract: Nature-based solutions are sustainable building materials produced recovering and enhancing agricultural biomasses which are by-products or waste of crops as, for example, rice, flax or hemp. Specifically, this research investigates the properties of hempcrete which is produced mixing lime, which acts as binder, and hemp shives, as vegetal aggregate. Hempcrete is characterized by breathability and excellent insulating properties, moreover it is a sustainable material due to the introduction of vegetal material and due to the carbonation of lime which gives further carbon dioxide sequestration. The mechanical properties of the material are largely variable and, in this research, triaxial tests have been performed to evaluate this experimental methodology as a technique applicable to evaluate the mechanical behavior of this material. The tests have been performed on samples produced with the same mix design developed by an Italian manufacturer for the production of prefabricated hempcrete blocks. These building components are used as non-loadbearing blocks, they are introduced in building envelopes or in indoor partition walls as insulating elements.

Abstract: This study aims to assess the impact of time on sawdust usage to enhance the behavior of the clay used in landfills. The soil used in this paper was brought from Büyükçekmece region / Istanbul. Four proportions (1, 2, 3 and 5) of the sawdust were added as a percentage of the dry weight of the soil. Soil-sawdust mixtures were compacted with the optimum water content corresponding to each percentage and samples were extracted. The extracted samples were divided into two groups, the immediate tests were performed on the first group while the second group was kept in special containers for long-term tests after 90 days. A series of undrained unconsolidated triaxial tests (UU) and unconfined compression tests (UCS) were performed on the specimens and compared with the row soil, in the immediate tests, the results from the UU triaxial test showed that the undrained shear strength was increased as the sawdust content increased and then decreased, it was conducted that the optimum sawdust content was 3%, it was increased the undrained shear strength by (39.5%) and (41.44%) for UU triaxial and Unconfined compression tests respectively. After 90 days of the curing period, it found that 2% is the optimum sawdust content, it was increased the undrained shear strength by (202.51%) and (176.64%) for UU triaxial and unconfined compression test respectively. In the immediate and long-term tests, the coefficient of permeability increased by (66.66) and (94.44%) as the sawdust increased from 0 to 5 % respectively. Sawdust increases the hydraulic conductivity of the clay. It can be concluded that the sawdust usage has a remarkable effect on the shear strength of the clay for both immediate and long-term tests.

Abstract: Constitutive models for soils are usually adopted in numerical method to analyze the behavior of geotechnical structures. This study performs a series of consolidated-undrained triaxial tests to establish the stress-strain curve of clay. A constitutive model that considers continuous strain hardening-softening is proposed based on the results of triaxial tests. Triaxial test results reveal that undrained shear strength linearly increases with an increase in consolidated pressure , the normalized undrained shear strength is about 0.52 not only for this study but also for the other two cases around Taipei Basin. Due to undrained condition, an associated flow rule between plastic strain increment and stress tensor is adopted. As accumulative plastic strain or/and consolidated pressure change, the mobilized undrained shear strength also changes. All parameters needed for the proposed model can be expressed as a function of undrained shear strength S_u, The mobilized undrained shear strength for the proposed model during strain hardening-softening can be in term of accumulative plastic strain. This model can calculate the stress-strain curves of clayed soils accurately.

Abstract: Modern models of soils to describe elastic-viscoplastic properties do not always lead to the desired results , especially when it is necessary to take into account the time factor. In particular, one cannot always describe the rheological model and creep and relaxation , as well as get extreme at kinematic mode loading. This is due to the fact that the deformation in the soil medium is accompanied by complex physical and physico-chemical phenomena , changes in the orientation of each mineral particles in space and time , their mutual offset seal ( hardening ) and decompression ( softening ) . Quantitative assessment of buildings and facilities associated with the calculation of the stress - strain state ( SSS ) foundation soils subject to numerous factors , including the physical feature of the power and influence ( statics, kinematics, dynamics ) and mechanical properties of soils under such effects ( creep , ductility ) .In the present paper the results of scientific studies of the rheological properties of sandy soils. The purpose of these studies - determination of viscosity sandy soils kinematic and dynamic triaxial test mode. A technique for determining the viscosity of soils results in triaxial kinematic mode (with speed control vertical movements). The paper considers the problem of estimating the impact of the dynamic loads on the viscosity of sandy soils.

Abstract: Swell-shrinking, crack development and over-consolidation are the characteristics of expansive soil, and it is an over-consolidation soil undergone dry-wet cycles. So there may be some faults to analyze expansive soil slope stability adopting the traditional strength criterion and calculation methods. In this paper, triaxial tests were carried out to obtain the relations between the parameters of shear strength and generalized plastic shear strain. The soil shear strength increases and then decreases along with the increasing of shear deformation due to soil over-consolidation. Moreover, the residual strength is achieved finally. The functions are applied in simulating the relations between the parameters and generalized plastic shear strain in order to analyze expansive soil slope stability.

Abstract: Duncan-Chang model can reflect soil’s nonlinear behavior much better, its’ concept is clear and easy to understand. In this paper, through triaxial test, parameters of Duncan-Chang model were gained by analyzing characteristics of Silt’s stress-strain Cures. A key factor, effecting silt’s stability, is the moisture content; there is a optimum moisture content in silt, in this moisture content, silt’s parameters of Duncan-Chang model can reach to the optimal state.

Abstract: Constitutive relation of soil is the core issue to study on soil’s mechanics characteristics. The stress-strain curve to silt belongs to intenerate type under low confining pressure and low moisture content, then silt features brittle failure; but it belongs to sclerotic type under high confining pressure and high moisture content, then silt features plastic failure. The conclusion of the article had some value for engineering’s design and calculation.

Abstract: The basic physical and mechanical characteristics of Clay shale in Bayingobi Basin of Inner Mongolia have been investigated by using supersonic testing system, rock mechanical testing system, and rock triaxial testing system. The results indicate that the deep clay shale of this region is characterized by high density, high mechanical strength, low deformation and strong brittleness. More specifically, according to the tests, because of their relative small particle size, the carbonate grains of clay rocks in this region are distributed more uniformly, and the average clay mineral content is comparatively low, as a result, the deep clay shale of this region are featured by large internal friction angle and high mechanical strength.

Abstract: Combustible ice is a kind of efficient and clean energy that has the potential to be exploited in the future, exploiting combustible ice needs to understand its mechanical properties. Combustible ice is another important feature of soil which is different from soil, in order to correctly understand the distinction, this paper using soil mechanics triaxial test method, to study the mechanical properties of combustible ice. Different from previous study, this article put forward the concept of simulated combustible ice, namely through baking powder, sodium chloride, and Marine sedimentary soil to simulate flammable ice, explore a new method for sample preparation to study the mechanical property of combustible ice.

Abstract: Red clay belongs to region special soil.It has engineering geological properties that are different from general soils.The natural red clay has high ratio void ratio,high moisturecontent,low density and so on.But red clay has non-corresponding high strength,bearing capacity of foundation and low compressibility. With the high speed development of China economy,the main soil named red clay in South is used as bearing stratum of many building foundations.However,when red clay is used as foundation,it is regarded as gerenal clay to consider its bearing capacity of foundation.So this will cause two disadvantages.First,potential is not given full play,resulting in considerable waste.Second,red clay has some special properties,such as high woid ratio,softening in water.These properties will bring hidden troubles,causing some bad accidents.These are caused by lacking of knowledge to engineering properties.Xiamen locates in southeast of China,and red clay is widely distributed.It is formed by accumulation through laterization of granites and basalts.So it is essential to study red clay.In this article,literatures of red clay in Xiamen are collected.Indoor conventional geotechnical tests are done,some engineering property parameters are obtained.