ANALYSIS OF EMBANKMENT SLOPE STEEPNESS AND STABILITY

This paper describes the stability calculations of the most common road embankments slopes and their results using the modified Bishop method. By searching for the smallest possible effective angle of internal friction of the different slope steepness embankments, the possible different bases of the embankment, the weight of the embankment soil, the load caused by transport and the location of load application (shoulder) were evaluated. Analyzing the obtained calculation results, it was determined that at a slope of 1:2 (26.57°) steepness, to ensure slope stability, the calculated effective internal friction angle of the embankment soil should be φʹd ≥ 28.5°, and at a slope of 1:1.75 (29.74°) steepness – φʹd ≥ 29.8°. When the slope is 2:3 (33.69°) steepness, the stability of the slope cannot be guaranteed.

Soil-Water Separation Property of Bauxite Mine Slime

Traditional disposal of the high-water content slime from the beneficiating and washing of the bauxite mine requires lots of land and a long time to consolidate, which has attracted a wide range of environmental and social concerns. High-speed centrifugal test was carried out to investigate the water property and composition of high-water content bauxite washing mud. Test results indicated that the bound water content ranged from 29.7% to 31.4%, free water content ranged from 250.6% to 252.3%. The bound water accounted for only 11%, while the free water accounted for about 89% of total water content. A series of model tests were conducted to study the slurry-water separation property of high-water content bauxite mine slime. Experiments showed that controlling the vacuum load application process can effectively inhibit the formation of low-permeability stratum around the drainage body. The final settlement increased by 31.5% and the amount of water discharge increased by 39.52% compared with the conventional vacuum preloading method. Moreover, the water content may decrease from 281.9% to 53.6% within 60 hours with the increase of density of drainage body under the controlled vacuum load application process.

Behavior of implant and abutment sets of three different connections during the non-axial load application: An in vitro experimental study using a radiographic method

BACKGROUND: During the masticatory cycle, loads of different intensities and directions are received by the dental structures and/or implants, which can cause micromovements at the junction between the abutment and implant. OBJECTIVE: The objective of this in vitro study was to evaluate the behavior of three different implant connections subjected to different load values using a digital radiography system. Additionally, the torque values for removing the abutment screws were also measured and compared. METHODS: Ninety sets of implant and abutment (IA) were used, divided into three groups according to the type of connection (n = 30 per group): EH group, external hexagon type connection; IH group, internal hexagon connection; and, MT group, Morse taper connection. RESULTS: MT group showed the better vertical misfit behavior at the three intensity of load applied, in comparison with EH and IH groups. In the analysis of torque maintenance (detorque test), MT group showed higher values of detorque when compared with the measured values of EH and IH groups (p < 0.001). CONCLUSIONS: The IA sets of EH and IH groups showed a microgap in all levels of applied loads, unlike the MT group this event was not observed. In the detorque test, MT group increase in the torque values when compared to the initial torque applied, unlike EH and IH groups showed a decrease in the initially torque applied in all conditions tested. A positive correlation was detected between the misfit and detorque values.

Experimental Studies of Fiber-Reinforced Concrete under Axial Tension

The design of a stand for testing concrete and fiber-reinforced concrete specimens-"eight" in tension, which provides axial load application and minimizes the effect of stress concentration at the ends of the specimen. The design of the stand is such that the distance between the axis of load application and the central hinge is 108 cm, and between this hinge and the axis of the test specimen is 21 cm, as a result of which the load transferred to the specimen is 5.143 times greater than the applied one. At the first stage of testing, it was found that the optimal characteristics of the fiber-concrete mixture is a matrix with a large aggregate ≤ 10 mm with 1.0% fiber reinforcement. At the second stage, the ultimate strength of fiber-reinforced concrete for axial tension was determined - 1.28 MPa when reinforced with wave fiber and 1.37 MPa when reinforced with anchor fiber, which amounted to 4.1% and 4.4% of compressive strength, respectively. It was also found that concrete reinforced with anchor fiber has higher deformation properties than concrete reinforced with wave fiber.

Stress Distribution in Implant-Supported Overdenture and Peri-Implant Bone Using Three Attachment Systems: A Finite Element Analysis

Background: This finite element analysis (FEA) evaluated stress distribution in implant-supported overdenture (ISO) and peri-implant bone using one extracoronal (ball) and two intracoronal (locator and Zest Anchor Advanced Generation (ZAAG)) attachment systems. Methods: In this in vitro study, the mandible was modelled in the form of an arc-shaped bone block with 33 mm height and 8 mm width. Two titanium implants were modelled at the site of canine teeth, and three attachments (ZAGG, locator, and ball) were placed over them. Next, 100 N load was applied at 90° and 30° angles from the molar site of each quadrant to the implants. The stress distribution pattern in the implants and the surrounding bone was analyzed, and the von Mises stress around the implants and in the crestal bone was calculated. Results: While minimum stress in peri-implant bone following load application at 30° angle was noted in the mesial point of the locator attachment, maximum stress was recorded at the distal point of the ball attachment following load application at 90° angle. Maximum stress around the implant following load application at 90° angle was noted in the lingual point of the ball attachment while minimum stress was recorded in the lingual point of the locator attachment following load application at 90° angle. Conclusions: According to the results, the locator attachment is preferred to the ZAAG attachment, and the ball attachment should be avoided if possible.

Design and Fabrication of Standing Wheel Chair

The wheelchair clients are presented to numerous physical and mental medical issues related with delayed situated stance with being inert in wheelchair, e.g., weariness, torment in hip joint, pressure injuries, and so forth Other related issues are expansion in guardian reliance, lower back torments among parental figures, and injury rates during move support, and so forth Numerous old subjects who can walk are confined in wheelchairs because of the absence of standing capacity. With less parental figures and expanded quantities of lower appendage handicapped and older subjects, there is a significant need of improved wheelchair plans focused on upgraded autonomy of wheelchair clients. The focal point of present work was at planning a novel reconfigurable wheelchair joined with stand and sit abilities with the end goal of improvement of freedom and personal satisfaction of lower appendage incapacitated and old subjects. Further work presents a general item plan and improvement periods of a reconfigurable wheelchair. The significant commitments of paper can be summed up as Modeling and creation of a proposed wheelchair and testing it in an ongoing requirement with load application. The proposed creative answer for the issues of long haul wheelchair clients has a promising potential to upgrade autonomy and personal satisfaction of crippled individuals.

On transmissible load formulations in topology optimization

Transmissible loads are external loads defined by their line of action, with actual points of load application chosen as part of the topology optimization process. Although for problems where the optimal structure is a funicular, transmissible loads can be viewed as surface loads, in other cases such loads are free to be applied to internal parts of the structure. There are two main transmissible load formulations described in the literature: a rigid bar (constrained displacement) formulation or, less commonly, a migrating load (equilibrium) formulation. Here, we employ a simple Mohr’s circle analysis to show that the rigid bar formulation will only produce correct structural forms in certain specific circumstances. Numerical examples are used to demonstrate (and explain) the incorrect topologies produced when the rigid bar formulation is applied in other situations. A new analytical solution is also presented for a uniformly loaded cantilever structure. Finally, we invoke duality principles to elucidate the source of the discrepancy between the two formulations, considering both discrete truss and continuum topology optimization formulations.