Characterization and Classification of Soils from Different Topographic Positions under Sugarcane Plantation in South Sulawesi, Indonesia

The varied topography will influence the soil formation. This study aims to characterize and classify the soil selected on different topography positions of the sugarcane plantation area. The research was conducted in sugarcane plantation area of Camming, District of Bone, South Sulawesi, which was carried out from November 2017 to March 2018. This study used a descriptive method, observation and description of the nine soil profiles at three transects. Each transect consisted of three profiles points located in different positions, consisting of summit, backslope, and valleys. Each horizon soil samples were analyzed for their physical, chemical and micromorphology characteristics in the laboratory. Soil classification system was done by using soil taxonomy to the level of subgroups. The results showed that an average rainfall annual on the research location was 2.200 mm per year. Soil characteristics such as soil solum, cation exchange capacity, and sum of basic cations tended to increase in parts of the valley than in the back and summit. The primary mineral from the sand fraction included quartz, calcite, biotite, opaque, and orthoclase found especially in the position of the back and valley. The pore types consisted of vugh and packing void pores. Pedofeature type of soil was generally in the form of concretions and nodules that showed the process of oxidation and reduction. The soil type in the study area was classified into Typic Haplustepts and Typic Haplustalf.

Numerical study on crack propagation in linear elastic multiphase composite materials using phase field method

PurposeThe purpose of this paper is to develop an efficient numerical method to study the complex crack initiation and propagation in linear elastic multiphase composites.Design/methodology/approachA phase field method is developed to study the complex fracture behavior in multiphase composites. A damage threshold is introduced for referring crack initiation in the proposed method. The damage threshold is assigned as a material property so that different composite components possess different thresholds. In this manner, smooth transition from crack initiation to propagation is revealed.FindingsThe proposed method is used to investigate complex crack evolution in mesoscale cementitious composite, which consists of aggregates, matrix and void pores. From a mesoscale point of view, it is found that cracks prefer to evolve within the matrix phase. As a crack encounters an aggregate, it tends to bypass the aggregate and evolve along the interface. Cracks tend to avoid to penetrate through aggregates. Also, cracks tend to be attracted by void pores. From a mesoscale point of view, it is revealed that the elastic modulus and strength of concrete models are closely related to porosity.Originality/valueA criterion with a damage threshold is introduced to the proposed method. The criterions with and without a damage threshold are compared with each other in details. The proposed method is proven to be a useful tool to study mechanical behavior and crack evolution of brittle multiphase composites.

Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores

This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively.