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Tsai P.-H.,National Cheng Kung University | Lee D.-H.,National Cheng Kung University | Kung G.T.-C.,National Cheng Kung University | Hsu C.-H.,China Engineering Consultants INC
Quarterly Journal of Engineering Geology and Hydrogeology | Year: 2010

The purpose of this study is to investigate the effect of content and plasticity of fines on the liquefaction resistance and the post-liquefaction volumetric strain ε v,pl of soils through a series of cyclic triaxial tests with remoulded samples considering various levels of cyclic stress ratio (CSR). Silt and clay were employed as the fines material, and the dry deposition method was used to prepare remoulded samples. Test results showed that for soils with silt fines (S soils), increase of fines content (FC) reduces the liquefaction resistance and causes larger ε v,pl,. Conversely, for soils with clay fines (C soils), increase of FC raises the liquefaction resistance and results in lower ε v,pl,. For the same level of FC and CSR, the liquefaction resistance of C soils is higher than that of S soils. The ε v,pl, of S soils is greater than that of C soils. For S soils, the ε v,pl, rises with increasing FC, whereas for C soils, the inverse result is obtained. These results show that the plasticity of fines affects the liquefaction behaviour of soils significantly. © 2010 Geological Society of London. Source

Weng M.C.,National University of Kaohsiung | Tsai L.S.,China Engineering Consultants INC | Liao C.Y.,National Taiwan University | Jeng F.S.,National Taiwan University
Tunnelling and Underground Space Technology | Year: 2010

This paper presents a shear-induced anisotropic degradation model involving time-dependent behavior to simulate the deformational characteristics of weak sandstone. The stress-strain relationship of the proposed model was originated from the degradation of moduli K and G subjected to different loading conditions. An anisotropic factor β is introduced to indicate the tendency of shear-induced volumetric deformation. Furthermore, to incorporate time-dependent deformation behavior of sandstone, this anisotropic degradation model is further extended using a generalized Burger's model. As a result, the proposed model is characterized by the following features: (1) being capable of describing shear-induced volumetric deformation, either compression or dilation, prior to the failure state; (2) being versatile in the time-dependent (creep) deformations; and (3) the anisotropic factor β serves as a convenient index regarding whether shear-induced volumetric deformation dilates or not. Afterward, the proposed model has been verified by comparing to experimental results. It is found that the proposed model is versatile in simulating short-term and long-term deformations of sandstone under different stress paths. Moreover, this model has been incorporated into finite element program and used to analyze a case of tunnel squeezing. Comparing with other existing models, it is found that the prediction of the proposed model is closer to reality and reveals a larger crown settlement, namely a squeezing condition, owing to larger extent of dilation zones. Overall, although the proposed model is a simple variable moduli model, it is capable of describing the key deformation behavior of weak sandstone reasonably-well, including time-dependent and shear-induced deformations. © 2010 Elsevier Ltd. Source

Wang J.-J.,National Taiwan University of Science and Technology | Chang T.-P.,National Taiwan University of Science and Technology | Chen B.-T.,National Taiwan University of Science and Technology | Wang H.,China Engineering Consultants INC
Journal of Sound and Vibration | Year: 2012

A new and quick approach is proposed to evaluate Poissons ratio of materials with only the measured longitudinal and cross-sectional resonance frequencies from the impact-echo test on a solid circular rod of known dimension. Both the longitudinal and guided wave propagation theories are used to derive the required equations through regression analysis. Procedure to verify the adequate length of solid rod specimen to obtain a valid Poissons ratio is described. Experimental data of four materials, concrete, steel, stainless steel and brass, illustrated with the proposed approach show satisfactory results. © 2011 Elsevier Ltd. All rights reserved. Source

Wang H.,China Engineering Consultants INC | Hsieh S.-C.,Nanyang Technological University | Lin C.,National Chung Hsing University | Wang C.-Y.,National Central University
Journal of Performance of Constructed Facilities | Year: 2014

In Taiwan, many bridges span rivers that exhibit severe channel variations in response to drastically increased flows and resulting floods caused by typhoons and storms. Flood-induced scour can undermine the effective embedment depth of bridge foundations. The Shuang-Yuan Bridge, spanning a downstream section of the Kaoping Stream, was severely damaged during Typhoon Morakot in August 2009. A qualitative investigation was conducted to determine the possible causes of this bridge collapse. Relevant hydrologic, meteorologic, structural, geotechnical, and terrain information from various sources both in written and image formats was collected, updated, and reviewed. The disaster investigation included field investigations, nondestructive inspection of bridge remnants, and investigation of structural damage of upstream river crossings, hydrologic changes, damage to training structures/embankment, riverbed profile changes, and debris during the flood event. Several inspections were applied to determine the embedment depths, positions of underwater remnants, and changes in riverbed elevation. The investigation results identified multiple possible causes of failure, including flood flows, river-bend-induced turbulent flows, and the joint effects of extended foundations and rafted wood. © 2014 American Society of Civil Engineers. Source

China Engineering Consultants Inc. | Date: 2014-04-14

A thin jack device for bridge lifting is disclosed, comprising a base seat; a lifting unit, movably connected with the base seat; and a displacement sensor, disposed at a side of the base seat. In this manner, an arrangement may be applied when a gap altitude between a bridge girder and a pier is insufficient to reduce a risk possibility of violation of the bridge and pier, and a displacement sensors attached to stroke is used to monitor a raised altitude to reduce a mechanical error to promote safety and thereby sufficiently the current pier structure to save a temporarily used pier or a frame based design and construction, whereby increasing the construction safety and decreasing the construction cost.

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