Advanced Materials Research Vol. 1020

Abstract: Combined with a highway tunnel testing and assessment, through the discussing of technical problems existed in tunnel’s quality detecting by the using of geology radar, using gist of geology radar in tunnel’s quality detecting is grasped, the key technologies of survey line layout, acquisition parameters setting and on-site test in the process of geological radar application are concluded. Relying on the field test data, lining thickness and dense degree of the left and right of spandrel and arch crown being in the safe use of phase are more deeply researched. The studies show that geological radar detection technology for tunnel nondestructive testing and evaluation is a kind of effective method, correlation detection technique and analysis method has some reference value to the similar tunnel structure.

Abstract: A new nonlinear discipline named Fractal theory which is a scientific theory and method studied the irregular of nature and complex phenomena has been used in civil engineering direction successfully in recent years. Take the Kuo changshan tunnel as an example, this paper will use the Range finder to measure the shape of surrounding rock along different longitudinal section contour line, then using the fractal theory to analyze it as follows: using section assumption, box counting method and higher dimensional method to calculate the fractal dimension, and to explore the relative relations between fractal dimension and stability of surrounding rock of the tunnel. The research results show that the more rough the tunnel longitudinal section contour line, the bigger the fractal dimension, the worse the corresponding stability of surrounding rock and the worse the lower the level of surrounding rock . Above all the tunnel longitudinal irregular section contour line has obvious fractal characteristics.

Abstract: In the present paper the model of beam on Winkler-type elastic foundation is used to model the underground tunnel. The soil displacement (mm)-stress (kpa) curve (p-s curve) is approximated in the form of hyperbolic type function by fitting the existing experimental data and then equivalent linear type of nonlinear bedding coefficient of foundation is derived from the fitting curve. Substitute the equivalent coefficient into the vibration equation of beam on Winkler-type elastic foundation, and we may assess the nonlinear effect of soil. Based on the hypothesis of large distance to earthquake source, Rayleigh wave is used to simulate the longitudinal shearing seismic wave. According to the amplitude attenuation law of Rayleigh wave in elastic half place, the effect of structure bury depth on dynamic response of underground tunnel is considered and the conception of critical bury depth is put forward. Finally the vibration differential equation of beam on Winkler-type elastic foundation is solved by using Matlab software, and the dynamic response of underground tunnel at different structure bury depth are compared. The results may provide a reference for practical engineering.

Abstract: The paper deals with the back analysis method in geotechnical engineering, that goal is evaluation the more objective and reliable parameters of the rock mass on the basis of in-situ measurements. Stress, deformational, strength and rheological parameters of the rock mass are usually determined by some inaccuracies and errors arising from the complexity and variability of the rock mass. This higher or lower degree of imprecision is reflected in the reliability of the mathematical modelling results. The paper presents the utilization of direct optimization back analysis method, based on the theory of analytical functions of complex variable and Kolosov-Muschelischvili relations, to the evaluation of initial stress state inside the rock massif.

Abstract: The development of railways brought a great era of tunnel construction in the 19^th century. One of the greatest obstacles for the railway between Bohumín and Žilina was the Jablunkov Pass. In 1869 the excavation of the first Jablunkov Tunnel started. In 1914 the second one came. However in the era of modern railway corridors these tunnels are no longer satisfactory, so a process of their modernisation was launched. Eventually the second tunnel was re-bored as a two-track tunnel. In 2007 the construction started, but in 2009 an exceptional event occurred, which significantly delayed the whole construction work. During the subsequent clearing of the cave-in a part of the tunnel from the northern portal remained in its definitive lining. Another part was temporarily secured with a concrete plug, while the original primary lining was reinforced with a railway bridge pier (PIŽMO). To get through the caved-in section and the concrete plug it was necessary to deploy blasting too. This created an opportunity to perform a unique experimental measurement of the impact of vibrations on the definitive lining from various sources (blasting and hydraulic demolition hammer). The generated vibrations might negatively affect the already finished definitive lining. All measurements were performed in amplitude and frequency area and the results were drawn as attenuation curves corresponding to the propagation of vibrations through the definitive lining construction.

Abstract: Modern tunnel structures are presently implemented primarily by conventional excavation, using the New Austrian Tunneling Method. Two linings are usually used to support the excavated area. The primary tunnel lining serves for consolidation of the extracting during tunneling and the secondary tunnel lining ensures the safe use of the structure during its life time. The design and evaluation of the tunnel lining is a comprehensive process that involves a lot of input conditions. We are not always able to define these inputs exactly. In order to specify the amount of secondary lining load, we must know not only the load by the rock but also e.g. the hydrostatic load and deformation behavior of concrete during its aging. The lining is also influenced by local climatic conditions. It is necessary to include effects of various temperatures on the lining in our design. The measurements carried out in the already completed structures serve us for a more exact determination of these temperatures. Based on the results from these measurements, we can determine the distribution of temperatures in the profile and the behavior of the construction versus the climate change more exactly. Monitoring the temperature development takes a long time. The specification of this behavior should lead to a material saving when new constructions are designed.

Abstract: Bridges are important element of transport system. If they are damaged, they must be replaced quickly. For this purpose, a number of temporary engineer equipment is used. Also, the bridge in the Czech Republic by small town Hustopeče nad Bečvou was replaced by this way. But the temporary solution has become a permanent solution. Engineer constructions, however, have a number of shortages and therefore, it was decided to modify them using anti-vibration mats. This is the first application of this type of mats, and it is necessary to detect any adverse impact on the bridge and its surroundings. The paper presents an analysis of the dynamic response upper layers of the bridge geological surroundings. The experimental seismic measurements were realized before mats installation and after it. All measurements were performed in amplitude and frequency area and the results were drawn as attenuation curves. The vibrations were also analysed according to the Czech relevant standards.

Abstract: Soil nails are components retaining a ground to give it support particular in cases when the ground doesn’t satisfy fully the requirements and it is expected an excessive deformation or the worst a collapse. Today in all geotechnical applications the soil nails are arranged in the simplest way i.e. they are all parallel and almost perpendicular the boundary face of the ground body to be bound. Submitted article is a feasibility study on application the soil nails in another a nonparallel scheme of nails arrangement. The nails are located in two closely adjacent parallel plains. The nails are inclined in each plain with regard to a boundary face of the ground body and the nail inclination heads in opposite direction in each plain. This way the nails build up a quasi-web scheme in the ground. Article analyzes the effect of the quasi-web scheme nails arrangement on the ground and looks for an exact solution to evaluate effect on ground strength and strain behavior. The force balance approach is employed for the exact analysis.

Abstract: The designs of the buildings are in addition to the static load exposed to ground vibrations spreading from the surrounding geological environment. Ground vibrations, which are produced by anthropogenic phenomena, are not usually the crucial load for the stability of the building. But this load have an adversely affect the walls of buildings or sensitive equipment in these buildings. This article will be deal with model study of underground barriers utilized as a protection against the spread of ground vibrations in geological environment. These underground barriers maybe used in the vicinity of roads or railway lines or in urban areas around the halls with heavy industrial activity. Material of underground barriers will be designed from material with different parameters, so that it could be assessed the best variant in terms of absorption of seismic waves. The different variations of the thickness of underground barriers and different distances from the source of vibration will be designed in the analysis. The analysis will be performed in mathematical models that will be created in the software’s based on the finite element method.

Abstract: The shaking table tests of a 1:7 scale model of three-floor steel frame base-isolated building was completed to study the seismic responses of base-isolated buildings under near-fault ground motions. Under the action of the typical near-fault seismic wave, the seismic responses of base-isolated structures increase with the increase of PGA. The maximum story displacements of super-structure decrease with increase of story. The velocity pulse has an adverse effect to acceleration responses of base-isolated structures. The isolation effect of base-isolated super-structures is still favorable under near-fault ground motions, but it will be necessary to add damping in isolation system or limit the displacement of bearings to prevent the excessive deformation of isolation layer.