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Lu B.,Northwest Research Institute Co.
Journal of Geomatics | Year: 2011

We describe the basic theory of SVD method and discuss the two strategies of SVD in ill-posed problems in geodetic data processing, which are truncated SVD and modified SVD. The method to choose the truncation parameter and modified singular value is given, and we compare the principle of each method on how to reduce the extent of ill-pose. Finally, an example is given to validate that the SVD method can solve the ill-posed problems efficiently and improve the precision and reliability of the solution.

Wang Y.S.,Lanzhou University of Technology | Wu L.H.,Northwest Research Institute Co.
Advanced Materials Research | Year: 2014

Based on the method for calculating seismic active earth pressure of soil-nailing retaining structures literature [1], the effect of horizontal seismic coefficient on seismic active earth pressure and the most dangerous sliding are analyzed in connection with practical engineering projects, and compared with the result which is not considered the seismic action. Results show that The existence of soil nails can effectively reduce the lateral pressure of supporting structures under earthquake ground motions and make the sliding surface slowly move to the wall back; Increased along with the height of soil nailing wall;With the increase of the height of soil nailing wall,facing wall the sliding movement amplitude increase under the action of earthquake, and the soil nail length is growing. © (2014) Trans Tech Publications, Switzerland.

Cheng J.-J.,Shihezi University | Xue C.-X.,Northwest Research Institute Co.
Journal of Wind Engineering and Industrial Aerodynamics | Year: 2014

The Qinghai-Tibet Railway (QTR) is the longest high-altitude railway in the world, which is frequently damaged by windblown sand. In order to prevent the sand damage, we constructed a sand-damage-prevention engineering system along the QTR. This was the first time a windblown-sand-prevention system was constructed in such a high-cold and arid environments; because of this, our work necessitated adjustments during the application of a number of different sand-damage-prevention engineering techniques. Based on detailed wind data and in situ observations of windblown sand, as well as systematic field measurements along the QTR, these sand-damage-prevention engineering measures were evaluated quantitatively and semi-quantitatively in this study. The results can be used to guide the design of sand-control structures, improve the existing sand-damage-prevention engineering system and optimize the structural performance of various sand-damage-prevention engineering measures. © 2013 Elsevier Ltd.

Sun S.-W.,China University of Mining and Technology | Zhu B.-Z.,Northwest Research Institute Co. | Wang J.-C.,China University of Mining and Technology
Soils and Foundations | Year: 2013

As one of the measures for slope fast reinforcement, micropiles are always designed as a group. In this paper, an analytic model for the ultimate resistance of micropile is proposed, based on a beam-column equation and an existing p-y curve method. As such, an iterative process to find the bending moment and shear capacity of the micropile section has been developed. The formulation for calculating the inner force and deflection of the micropile using the finite difference method is derived. Special attention is given to determine the spacing of micropiles with the aim of achieving the ultimate shear capacity of the micropile group. Thus, a new design method for micropiles for earth slope stabilization is proposed that includes details about choosing a location for the micropiles within the existing slope, selecting micropile cross section, estimating the length of the micropile, evaluating the shear capacity of the micropiles group, calculating the spacing required to provide force to stabilize the slope and the design of the concrete cap beam. The application of the method to an embankment landslide in Qinghai province, China, is described, and monitoring data indicated that slope movement had effectively ceased as a result of the slope stabilization measure, which verified the effectiveness of the design method. © 2013 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved.

Wu X.,Lanzhou University | Wu X.,Northwest Research Institute Co. | Chu H.,Northwest Research Institute Co. | Wang L.,China Earthquake Administration
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2015

The lower bound depth of the self-weight collapse of loess is used to determine the type and grade of a collapsible loess foundation. It is important to select a reasonable foundation treatment depth and to determine negative skin friction neutral points of the pile. This study comprehensively analyses the differences between laboratory and fullscale field testing in determining the lower bound depth of the self-weight collapse of loess. Although this lower bound depth tends to be a unique value, obvious differences were obtained in the test results obtained by the two methods. Generally, the laboratory test results were 1·25–2·90 times greater than those of the field test, mainly owing to differences in saturation, test pressure, the sample stress state and soil non-uniformity. Evaluation of the lower bound depth of the self-weight collapse of loess should therefore be based on field testing and the results from laboratory tests need to be modified. This paper puts forward a new theoretical modification method for this purpose, which could reduce the differences between laboratory and field test results. © 2015, Thomas Telford Services Ltd. All rights reserved.

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