Temperature effect on compression and collapsibility of residual granitic soil

U ovom se radu istražuje utjecaj temperaturnih promjena na indeks stišljivosti i potencijal kolapsibilnosti rezidualnog granitnog tla na koje se često nailazi u Maleziji. Zbijeno tlo analizirano je pomoću modificiranog edometra s kontrolom temperature. Dvije serije uzoraka tla s raznim vrijednostima suhe gustoće ispitane su pri temperaturama od 27, 40 i 60°C. Rezultati ispitivanja pokazuju da vrijednost indeksa stišljivosti ne ovisi o temperaturi. S druge strane, grijanje dovodi do smanjenja potencijala kolapsibilnosti, a ta je pojava izraženija pri niskim vrijednostima suhe gustoće.This research aims to investigate the effect of temperature changes on the compression index and collapse potential of the residual granitic soil that is widely encountered in Malaysia. An experimental study was conducted on the compacted soil using a modified temperature-controlled oedometer. Temperatures of 27, 40, and 60 ºC were applied on two series of soil specimens with different values of dry density. Experimental results showed that the value of compression index is independent of temperature. On the other hand, heating caused a reduction in collapse potential, which was more pronounced at low dry density

COMPARISON OF DIFFERENT MEDIA TO PRODUCE CYMBIDIUM ORCHIDS BY PSEUDOBULBS

Nowadays, Orchids are one of the most commercial products in flower markets. One of the propagation methods for Cymbidium is using old pseudobulbs that are thrown out after flowering period. This research carried out using standard Cymbidium back-bulbs based on randomized complete block design with 5 treatments in 3 replications. The trial traits were leaf length, root length, leaf number and root number that were studied for 180 days. The results show that minimum length of root was significant under different growth beds. The minimum percent of rooting was observed in pure sand treatment. The maximum length was observed in pure perlite. The shortest of leaves were gained in perlite + sand treatment and the maximum leaf length was observed in pure perlite treatment. The maximum average of root percent was seen in pure perlite treatment

The application of particle swarm optimization in slope stability analysis of homogeneous soil slopes

This paper applies particle swarm optimization (PSO) to find the most possible failure surface in stability analysis of homogeneous soil slopes. The stability of slopes is an important issue on geotechnical engineering. This problem includes two general concepts, factor of safety (FOS) and the critical slip surface (CSS). The resultant ratio of dividing strengthens forces by driving forces is called FOS. The critical slip surface is defined as a failure surface with the minimum value of FOS among all candidates. Regarding to the vast number of trial slip surfaces and the non-linear nature of equation of FOS, a global optimization algorithm is needed to locate CSS. As an optimization technique, the original version of PSO with little improvements in initial parameters is used. With this aim in view, we developed a computer code to find CSS by particle swarm optimization. Moreover, a sensitivity analysis is conducted to find the optimum values of initial parameters of PSO. Finally the effectiveness and efficiency of PSO code is verified and compared with the benchmark examples from the literature. The results demonstrated the ability of PSO to find CSS with better outcomes than former methods

An improvised three-dimensional slope stability analysis based on limit equilibrium method by using particle swarm optimization

The stability of slopes is a major concern in the field of geotechnical engineering. Two-dimensional (2D) limit equilibrium methods are usually implemented in this field due to their simplicity. However, these methods ignore the features of the third dimension of slopes. Although three-dimensional (3D) methods tried to remove the previous limitation, most of them assumed the direction of sliding, simplified or ignored the intercolumn forces, and avoided to search for location and shape of three-dimensional critical slip surface. This study was performed to overcome the mentioned limitations. In the present study, a new slope stability method was established based on the force and moment equilibrium in two vertical directions that was able to find the unique direction of sliding. Moreover, a modified Particle Swarm Optimization was developed by replacing the worst particle of each swarm with the previous global best particle and using a dynamic inertia weight to determine the 3D critical slip surface. Then, a computer program was established to model 3D slopes and perform the required calculations. Several benchmark problems were re-analyzed to verify the results of the study and good agreements were achieved with the results of previous studies when different failure mechanisms as ellipsoid, cylindrical, and composite slip surfaces were successfully applied in the analysis. The results indicated that the 3D factor of safety of a slope is always greater than its corresponding 2D factor. Moreover, the end effect in 3D analysis was found to be more significance in the problems with lower ratio of length to the width of the sliding mass. It was also found that the presence of water and weak layer enlarged this effect. Through the verification study, it was observed that different sliding directions produce different factors of safety, while the lowest value of factor of safety and 3D critical slip surface is only reachable through the real direction of sliding. Finally, case studies of actual stability problems were analyzed to find their critical slip surfaces. Achieving the minimum factor of safety of 0.977 for the critical slip surface of a failed slope demonstrated the validity of performance of presented computer code. Based on the obtained results, this study successfully overcame the mentioned limitations of the previous methods. The results of this study provided a better understanding of the actual failure mechanism and helped to enhance the safety and reduced the economic and health costs due to slope failure by a more detailed analysis than before

Evaluation of Liquefaction Properties of East Coast Sand of New Zealand Mixed with Varied Kaolinite Contents Using the Dynamically Induced Porewater Pressure Characteristics

In earthquake geotechnical engineering, physical model experiments have proven to be significant and valuable in understanding the complex physics and engineering behaviors of prototype undrained soils in fields. An executed literature review indicated that large-scale physical model testing, such as shaking table (ST) and centrifuge devices, have associated advantages and limitations. The current paper presents the design, fabrication, and calibration of a 600N-capacity, small-scale, one-directional (1-D) laboratory ST device that enables quick and valuable assessment of soil liquefaction mechanisms. The dynamically induced porewater pressure (PWP) generation characteristics of sand soil mixed with different percentage weights of clay were evaluated and illustrated as a case study for testing the ST device’s performance. The east coast sand (ECS) of New Zealand’s North Island was mixed with different percentages of kaolinite clay to produce five variants of ECS (00, 05, 10, 20, 25, and 30). Three input sine wave ground motions of a constant frequency of 10 Hz and amplitudes of 2, 3, and 4 were applied and classified in the current study as low, intermediate, and moderate ground motions, respectively, to evaluate the evolution of the dynamic excess pore pressures in the soil samples. The results indicated that the clean ECS and mixed samples with lower clay content (ECS00, ECS05, ECS10, and ECS15) produced the highest excess PWP throughout the three shaking cycles, with higher tendencies of contraction and liquefaction properties. On the other hand, soil samples with a higher percentage of clay (ECS20 and ECS20) yielded the lowest PWP, with softening and dilative properties

Simulation of longitudinal surface settlement due to tunnelling using artificial neural network

A series of artificial neural networks modelling was conducted to investigate the ground deformation induced by tunnelling along the line 2 of Karaj urban railway, Iran. The tunnels were excavated using New Austrian Tunnelling Method. During excavation, surface settlement was monitored using optical survey points installed on the centre, left and right sides of the tunnel axis. The measured data have been used to establish an artificial neural network model to predict longitudinal surface settlement. This paper focuses on the prediction of ground deformation due to tunnelling using artificial neural networks, particularly longitudinal settlements in relation to the ground condition and tunnelling method. The obtained results demonstrate that artificial neural networks are applicable techniques for predicting longitudinal surface settlement due to tunnelling

Indirect measure of thermal conductivity of rocks through adaptive neuro-fuzzy inference system and multivariate regression analysis

Thermal conductivity is an important property of rocks which is considered for energy-efficient building construction. This paper is aimed to predict the thermal conductivity of rocks utilizing the adaptive neuro-fuzzy inference system (ANFIS) and multivariate regression (MVR) analysis. In this regard, 44 datasets including the most effective parameters on thermal conductivity of rocks were collected from the literature. The physico-mechanical properties of rocks including uniaxial compressive strength, P-wave velocity, bulk density and porosity were used to develop the predictive models. The correlation of determination equal to 0.99 and 0.95 were obtained by ANFIS and MVR models respectively. The obtained results suggest that the ANFIS model outperforms the MVR model and is an applicable tool to predict thermal conductivity of rocks with high degree of accurac

Applications of Particle Swarm Optimization in Geotechnical Engineering: A Comprehensive Review

Particle swarm optimization (PSO) is an evolutionary computation approach to solve nonlinear global optimization problems. The PSO idea was made based on simulation of a simplified social system, the graceful but unpredictable choreography of birds flock. This system is initialized with a population of random solutions that are updated during iterations. Over the last few years, PSO has been extensively applied in various geotechnical engineering aspects such as slope stability analysis, pile and foundation engineering, rock and soil mechanics, and tunneling and underground space design. A review on the literature shows that PSO has utilized more widely in geotechnical engineering compared with other civil engineering disciplines. This is due to comprehensive uncertainty and complexity of problems in geotechnical engineering which can be solved by using the PSO abilities in solving the complex and multi-dimensional problems. This paper provides a comprehensive review on the applicability, advantages and limitation of PSO in different disciplines of geotechnical engineering to provide an insight to an alternative and superior optimization method compared with the conventional optimization techniques for geotechnical engineers

Pre and post-harvest effect of gibberellic acid and salicylic acid on cut branches of Asparagus umbellatus

Asparagus umbellatus is one of the most popular cut foliage plants that widely used in decorations and bouquets. However, there was a lack of information concerning Asparagus postharvest handling. Therefore, in this study, two growth regulators gibberellic acid (GA) and salicylic acid (SA) on concentrations of 0, 100, 200, and 400 μM were applied in two stages viz., pre and postharvest, separately and in combination. Experimental traits including; chlorophyll content, electrolyte leakage, solution uptake, microbial population, relative water content (%), malondialdehyde content, catalase, superoxide dismutase, and peroxidase activity along with plant vase life were evaluated. The results showed that the application of GA and SA lead to significantly extension of the vase life compared to the control. Vase life difference between control (9.34 days) and the superior treatment i.e. GA200+SA200 (14.07 days) was more than 50%. Also, the pre-harvest foliar application of GA and SA increased the vase life slightly compared to the application in vase solution. The extended vase life in the per-harvest experiment was obtained using SA100+GA100 and SA200+GA200 treatments

Assessment of antifungal effects of copper nanoparticles on the growth of the fungus Saprolegnia sp. on white fish (Rutilus frisii kutum) eggs

This study was conducted to evaluate the in-vitro effects of copper nanoparticles on the growth of the fungus Saprolegnia sp. isolated from white fish (Rutilus frisii kutum) eggs. The antifungal effects were measured by determining the minimum lethal concentration of copper nanoparticles on Saprolegnia sp. in yeast extract glucose chloramphenicol (YGC) agar at 25 °C. Saprolegnia grown in YGC agar without added copper nanoparticles served as negative controls. Our study showed that copper nanoparticles at a minimum concentration of 10 ppm have antifungal effects on Saprolegnia sp. The antifungal effects of copper nanoparticles are positively correlated to both concentration and time of exposure. This study showed that the antifungal properties of copper nanoparticles make it a good alternative to malachite green, which is carcinogenic