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Sun S.,Northwest Research Institute Co. | Sun S.,Tsinghua University | Zhu B.,Northwest Research Institute Co. | Ma H.,Northwest Research Institute Co.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

Based on the model experiments, the anti-sliding characteristics of micropiles with cap beam were studied. It was shown that, a hyperbolic function could be used to describe the relationship of load and lateral displacement of micropile head. Micropiles in the rear row were trend to be pull out and the cap beam is tilt during the loading process. It was shown by monitoring the soil pressure that pushing force acting on micropiles with cap beam was trapezoidal distribution, and the resistance force below sliding surface was inverted with triangular distribution. The soil pressure value was larger at micropile head and around sliding surface and smaller at the bottom of micropiles. The ratio of pushing force acting on the micropiles between the rear row and leading row was 1:0.6. Micropiles with cap beam and smaller spacing of micropile have larger anti-sliding capacity, but under the same value of the acceptable displacement, there was not a big difference between the two structures in the experiment. The pile cap beam could restrain the lateral displacement of micropile head and reduce the bending moment of micropile body effectively, meanwhile produce a higher bending moment at the micropile head, thus some methods, i.e. installing an oversized casing in the top portion of micropile, constructing a larger pile diameter at the top, embedding the pile cap deeper and so on could be adopted reasonably in engineering practice.

Zheng J.,Northwest Research Institute Co. | Zeng H.,Northwest Research Institute Co. | Zhu B.,Northwest Research Institute Co.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

The erosion situation, erosion rate and mechanical behavior rules of steel strands in anchors with time have been analyzed and studied through taking erosion tests in strong erosion condition on four types of anchors as steel strand and injection cavity defect anchor with or without prestressing separately. The mechanical behavior reduction of steel strands in anchors and the mechanical behavior reduction differences among various types of samples have been analyzed as well. The regression analysis of the variation of the fracture load of erosion anchor samples with time is conducted. The study results show that in the same erosion condition, the erosion rate of anchors with injection cavity defects(or with broken PE casings or bellows) is faster than steel strand, of course much faster than anchors without defects. Stress erosion has great effect on the mechanical behavior of steel strands in anchors. Based on various tests of the fracture load of steel strands in anchors with erosion time in different erosion conditions, the fracture load can be inferred in a certain erosion condition through the regression curves of relationship between fracture load and time for steel strands in anchors. Therefore, the safety assessment and life prediction to anchors can be carried out.

Lin C.,Northwest Research Institute Co.
Civil Engineering and Urban Planning III - Proceedings of the 3rd International Conference on Civil Engineering and Urban Planning, CEUP 2014 | Year: 2014

Based on time domain reflectometry (TDR) technology, this paper describes the research centering on slope's automatic monitoring and warning alarm. Upon TDR's fundamental theory and carrying out coaxial-cable deformation and destruction simulating experiments, the features of coaxial-cable deformation and destruction and their respective reflection rules were understood. Moreover, both coaxial-cable arrangement and grout, data automatic collection and remote transmission, were studied. In addition, deformation threshold values ere investigated. Finally, a complete set of software, including data processing and monitoring and warning alarm, was developed. Slope's real-time monitoring and warning alarm were realized at last. © 2014 Taylor & Francis Group.

Yao Z.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Xiao J.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Jiang F.,Northwest Research Institute Co.
Aeolian Research | Year: 2012

Severe wind is a major natural hazard in Xinjiang Uygur Autonomous Region, China. Using a 55-station network, we collected wind statistics along the Lanxin Railway, particularly in the Alashankou, 30-li, and 100-li wind zones. Wind speed and direction varies throughout the province: the mean speed of extreme wind gusts is greater in the north where wind direction is mainly western and northwestern; in the south the wind direction is primarily northeastern and southeastern. Detailed analyses show that the prevailing direction of extreme winds follows the gaps of the mountain. The terrain effect enhances wind speed and creates the three wind zones. Severe winds occur mostly in during April and August and are caused primarily by Siberian cold fronts (spring) and thunderstorms (summer). We analyzed the probability of extreme wind speed using the Gumbel Model, and calculated annual maximum daily extreme wind speed values for the three wind zones over desired return periods. © 2012 Elsevier B.V.

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.

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

The finite element model of the space KX-Joint was established using ANSYS software, and the failure mode and ultimate bearing capacity of KX-joint were researched. Calculation results show that the surface of chord wall on the roots of compression web members was into the plastic in K plane, and the holding pole without the plastic area and the local buckling failure happened in the surface of chord wall on the roots of Compression Web Members in X plane; The bearing capacity of the joint increased with the Chord diameter, which was appears in the form of power function. © (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.

Qu Y.,Northwest Research Institute Co. | Miao X.,Northwest Research Institute Co.
Zhongguo Tiedao Kexue/China Railway Science | Year: 2015

Piles thrusted-expanded with column-hammer, compaction piles and dynamic compaction were used respectively in the treatment of high speed railway subgrade in collapsible loess areas. Surcharge preloading settlement observations and continuous water immersion tests were carried out on the test section foundation to study the applicability of three ground treatment methods used in the construction of high speed railway. The results show that, the total foundation settlements treated with these three methods are all from the part which is under the treatment depth. The remaining settlement of the piles thrusted-expanded with column-hammer treated and the compaction piles treated subgrade at the ultimate treatment depths can meet the technical requirements of subgrade settlement for high speed railway after 3 months and 6 months surcharge preloading respectively. While the remaining settlement of the dynamic compaction treated subgrade at the ultimate treatment depth still cannot meet the technical requirements of subgrade settlement for high speed railway after 258-day surcharge preloading. The above-mentioned three methods can well control the settlement deformation within the subgrade treatment depth under the condition of continuous water immersion. It is clear that the methods of piles thrusted-expanded with column-hammer and compaction piles can get satisfied settlement control effects on the treatment of subgrade for high speed railway in loess areas and it is suggested that these two methods be used in the loess site with the lower depth limits less than 20 and 15 m respectively. When treatment depth is less than 6 m, the method of dynamic compaction together with the method of CFG piles can be used. © 2015, Chinese Academy of Railway Sciences. All right reserved.

Northwest Research Institute Inc. | Date: 2012-02-02

Alloys of common metal; Alloys used for casting; Common metals and their alloys including stainless steel; Metal alloys for further manufacturing; Metal profiles made of steel, iron, nickel, titanium and other metals and their alloys; Metals and metal alloys; Non-ferrous metals and their alloys; Rods of metal for brazing and welding including those from alloy steel and titanium.

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