Tunneling in Various Shapes Using Numerical Analysis

Tunnelling has gained popularity in the recent times due to lack of space and the rapidly increasing population. Thus, going underground is the only option to provide the infrastructure facilities which will meet the need of increasing population. The shape and dimensions of the tunnel cross section usually depends on certain parameters like purpose for which the tunnel is provided, drainage & maintenance requirements, requirement of escape route, etc. Geology plays an important role in deciding the shape of the tunnel. The ground behaves in a complex manner, when a tunnel is excavated in it as new stresses are developed. Based on the ground types, the shape is selected in such a way that the stresses developed in the ground should distribute properly around the tunnel periphery and should not cause convergence of the tunnel boundary. Also, requirement of support system should not be too heavy, as it will increase the cost. Apart from the above parameters, the availability of the equipment & the construction method also decides the shape of the tunnel. There are various shapes of tunnels like D-shape, Circular, Elliptical, Egg-shape, Box type, Horseshoe & Modified Horseshoe shape. In the present course of work three shapes of tunnels viz. Horseshoe Shape, Modified Horseshoe Shape & D-Shape tunnels are considered. By hypothetical assumption the geology and overburden are taken into account for the tunnels and the tunnels are simulated for roof collapse and shear failure case by using RS2 FEM based software.

Seismic response analysis of steel–concrete hybrid wind turbine tower

The steel–concrete hybrid wind turbine tower is characterized by the concrete tubular segment at the lower part and the traditional steel tubular segment at the upper part. Because of the great change of mass and stiffness along the height of the tower at the connection of steel segment and concrete segment, its dynamic responses under seismic ground motions are significantly different from those of the traditional steel tubular wind turbine tower. Two detailed finite element models of a full steel tubular tower and a steel–concrete hybrid tower for 2.0 MW wind turbine built in the same wind farm are, respectively, developed by using the finite element software ABAQUS. The response spectrum method is applied to analyze the seismic action effects of these two towers under three different ground types. Three groups of ground motions corresponding to three ground types are used to analyze the dynamic response of the steel–concrete hybrid tower by the nonlinear time history method. The numerical results show that the seismic action effect by the response spectrum method is lower than those by the nonlinear time history method. And then it can be concluded that the response spectrum method is not suitable for calculating the seismic action effects of the steel–concrete hybrid tower directly and the time history analyses should be a necessary supplement for its seismic design. The first three modes have obvious contributions on the dynamic response of the steel–concrete hybrid tower.

A source-sink approach for computation of intensity of low-potential underground heat non-stationary extraction

A new methodology for estimation of changing intensity characteristics of non-stationary heat transfer in underground heat extraction by a single-pipe upright heat exchanger is presented in this paper. Major trends in changing of a heat removal volume, linear heat transfer coefficient, linear heat transfer resistance, and heat sink radius have been estimated for specific ground types. Also a generalized one-factor linear semilogarythmic equation has been developed for specific ground types, along with an appropriate approximating function intended to simplify the underground heat extraction intensity estimation methodology.

Seismic Structural Analysis of Buried Pipelines and Safety Evaluation Model Based on Response Surface Method

Based on the earthquakes that occurred recently in Gyeongju and Pohang provinces, the Korea Peninsula needs to be prepared for a strong earthquake that might occur in the future. In this study, a strain tendency model based on the response surface method was used to analyze buried straight pipelines. The strains of the buried pipelines were computed through structural dynamics analysis, considering the section properties and ground types. In the case of the buried straight pipelines, this strain tendency model provided the necessary information for setting the strain-based design and a guideline for predicting post-earthquake damages in the Korea Peninsula.

ANALYSIS OF THE INFLUENCE OF GROUND TYPES ON SEISMIC RESPONSE OF MULTI-STOREY FRAME STRUCTURE

Experiences from previous earthquakes have shown that level of structural damages depends onground features where the structure is placed. Also, it is noted that reinforced concrete framestructures collapse due to the appearance of “weak floor”, especially when are founded on groundswith lower characteristics. In this paper, the seismic analysis of structure is presented on example ofthe six-storey RC frame structure, founded on different ground types. The seismic analysis isperformed in accordance with European regulations and still valid ex-Yugoslavian code PIOVSP'81.At the end of the paper, a comparison of the results was made, and corresponding conclusions werereached.

Comparison of Trotting Stance Detection Methods from an Inertial Measurement Unit Mounted on the Horse’s Limb

The development of on-board sensors, such as inertial measurement units (IMU), has made it possible to develop new methods for analyzing horse locomotion to detect lameness. The detection of spatiotemporal events is one of the keystones in the analysis of horse locomotion. This study assesses the performance of four methods for detecting Foot on and Foot off events. They were developed from an IMU positioned on the canon bone of eight horses during trotting recording on a treadmill and compared to a standard gold method based on motion capture. These methods are based on accelerometer and gyroscope data and use either thresholding or wavelets to detect stride events. The two methods developed from gyroscopic data showed more precision than those developed from accelerometric data with a bias less than 0.6% of stride duration for Foot on and 0.1% of stride duration for Foot off. The gyroscope is less impacted by the different patterns of strides, specific to each horse. To conclude, methods using the gyroscope present the potential of further developments to investigate the effects of different gait paces and ground types in the analysis of horse locomotion.

The Effect of Ground Type on the Jump Performance of Adults of the Locust Locusta migratoria manilensis: A Preliminary Study

The jump performance of locusts depends on several physiological and environmental factors. Few studies have examined the effects of different ground types on the jump performance of locusts. Here, mature adult locusts (Locusta migratoria manilensis) were examined using a custom-developed measuring system to test their jump performance (including postural features, kinematics, and reaction forces) on three types of ground (sand, soil, and wood). Significant differences were primarily observed in the elevation angle at take-off, the tibial angle at take-off, and the component of the mass-specific reaction force along the aft direction of the insect body between wood and the other two ground types (sand and soil). Slippage of the tarsus and insertion of the tibia were often observed when the locusts jumped on sand and soil, respectively. Nevertheless, comparisons of the different parameters of jump initiation (i.e., take-off speed and mass-specific kinetic energy) did not reveal any differences among the three types of ground, indicating that locusts were able to achieve robust jump performance on various substrates. This study provides insights into the biomechanical basis of the locust jump on different types of ground and enhances our understanding of the mechanism underlying the locust jump.

Heavy metals as indicators of dynamics of the circulation of substances on recultivated lands of the Western Donbass

The biological cycle of matter in artificial plantations of forest rehabilitation sites of the Western Donets Basin was studied. The content and patterns of microelements’ migration in plants, tree waste, litter and soils are determined. Manganese, copper, lead, chromium, nickel and titanium were under investigation. The dependence between the microelements content in tree waste, litter and soil and their main physicochemical characteristics as well as the correspondence of forest growing conditions to the optimal limits of the elements’ content in soil for plants normal development are characterized. The factors influencing the trace elements content in the fill-up reclaiming layer are analyzed. The reasons for the wide variation range of the microelements content in the leaves of experimental trees, and the possibility of using different ground types and plantation patterns are explained. It makes possible to estimate the importance of the biological stage of rehabilitation for the preventing technogenic influence on the environment.