China JK Institute of Engineering Investigation and Design
China JK Institute of Engineering Investigation and Design
Shen Y.-X.,Lanzhou University |
Chen W.-W.,Lanzhou University |
Kuang J.,Gansu Building Research Institute |
Du W.-F.,China JK Institute of Engineering Investigation and Design
Journal of Central South University | Year: 2017
Salt weathering leads to destruction of many valuable cultural heritage monuments and porous building material. The present study aims at providing more laboratory evidence for evaluating the effects of salt precipitation on the deterioration process. In view of this, the remoulded soil specimens were mixed with three kinds of salts (i.e., NaCl, Na2SO4 and their mixture) with different salt concentrations, and the specimens were kept in environment cabinet for undergoing different wet-dry cycles. After each cycle, the ultrasound velocity measurements were employed to monitor the deterioration process. For the specimens that have suffered three wet-dry cycles, the mechanical properties (i.e. shear strength and compression strength) were determined to evaluate the degree of deterioration. Furthermore, considering the realistic conservation environment of earthen sites, mechanical stability of these specimens against sediment-carrying wind erosion was conducted in a wind tunnel. These experiments results indicate that the overall average velocities of the specimens after the third cycle are significantly lower than those subjected to only one cycle. Ultrasound velocity, mechanical strength and wind erosion rate decrease when salt content increases. However, the internal friction angle increases firstly, and then decreases with the increase in salt content added to the specimens. Na2SO4 contributes most of the surface deterioration, while NaCl plays little role in the deterioration. The damage potential of the salt mixture is less obvious and largely dependent on the crystallisation location. © 2017, Central South University Press and Springer-Verlag Berlin Heidelberg.
Mu H.-D.,Xi'an University of Technology |
Song D.-Y.,China JK Institute of Engineering Investigation and Design |
Deng Y.-H.,Chang'an University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2016
The landslide is a common geological disaster, and the loess landslide instability induced by irrigation is one of the common geological disasters. Irrigation function changes the balance of ground water and reduces the resistance strength of soil mass, resulting in the occurrence of loess landslides. For the loess landslide No.13 of Jiaojiayatou, centrifugal model tests on landslide instability mechanism under irrigation effect are carried out. The deformation characteristics, stress levels and failure modes are revealed. The preporation of centrifugal model considers the influences caused by "particle size effect" and "size effect". The results show: (1) With the increase of loading time and centrifugal acceleration, the settlement, earth pressure, pore water pressure of model slope all gradually increase. (2) The slope settlement gradually decreases from the slope top to the toe. The maximum vertical displacement is 33.38 mm. The soil pressure of slope gradually increases from the slope top to the toe. The largest earth pressure is 320 kPa, the pore water pressure is the largest at the slope top, that at the toe is followed, and that in the middle is the smallest, and the maximum pore water pressure is 157.08 kPa. (3) The slope emerges two failure modes: one is creep deformation of the toe and pressure-induced crack of the top, the other is shear slip of the slope. © 2016, Editorial Office of Chinese Journal of Geotechnical Engineering. All right reserved.
Zheng J.-G.,China JK Institute of Engineering Investigation and Design |
Deng G.-H.,Xian Metro Ltd. |
Liu Z.-H.,China JK Institute of Engineering Investigation and Design |
Chen R.-S.,China JK Institute of Engineering Investigation and Design |
And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2015
Investigating the difference between the calculated and measured values of the collapsible settlement is useful and necessary to accurately evaluate the loess collapsibility. Although the difference has been noted by many researches, it has not yet been examined deeply and systematically. Based on the results of two field loess immersion tests in Xi'an loess tableland area, the numerical method is used to compare the collapsible deformations of loess foundation with different proportions and arrangements of collapsible and non-collapsible soils as well as with different collapsible degrees of collapsible soils. The results reveal that the inhibition effect on collapsible deformation, which is caused by the discontinuous distribution of collapsible loess, is one of the main reasons for the discrepancy between the calculated and measured values of the collapsible settlement. In addition, this inhibition effect is more significant for the cases with more random distribution of collapsible and non-collapsible soils, or with higher proportion of non-collapsible soils. Through comparison, the impact on the inhibition effect caused by the collapsible degree of collapsible soils is not very strong. The inhibition effect should be taken into account in calculating the collapsible deformation, and the related data should be collected and summarized in future engineering practice. ©, 2014, Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering. All right reserved.
Wang X.,Xi'an Jiaotong University |
Tao W.,Xi'an Jiaotong University |
Tao W.,China JK Institute of Engineering Investigation and Design |
Xu Y.,University of Texas at Austin |
And 2 more authors.
Atmospheric Environment | Year: 2014
Indoor phthalate levels were investigated in 28 buildings, including 14 office and 14 residential buildings in Xi'an, China. Phthalate esters in the gas-, particle-, and dust- phase were measured separately. Four phthalates including dimethyl phthalate (DMP), diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP) were detected. The detection frequency of DnBP and DEHP was more than 90%. The concentrations of total phthalate esters ranged from 0.20 to 8.29μgm-3 for the gas- phase, from 0.09 to 14.77μgm-3 for the particle- phase and from 123 to 9504μgg-1 for the dust- phase. The individual phthalate with the highest concentrations of 6.17μgm-3, 7.97μgm-3 and 7228μgg-1 respectively for gas-, particle- and dust- phase in all investigated rooms is all DiBP. The median concentration of the gas- and particle-phase DiBP (0.52 and 0.72μgm-3) and dust-phase DEHP (582μgg-1) were the highest. It was also found that the average concentrations of individual phthalates in residential buildings were often higher than in office buildings, and correlation analysis indicated that DiBP, DnBP and DEHP might come from the same sources. Based on the gas- and particle-phase concentrations measured, the particle-air partition coefficients of phthalates were estimated, and their logarithm values were found to be linearly correlated with the logarithm values of their octanol-air partition coefficients. Finally, the total daily exposure to indoor phthalates in air and dust was calculated, and ranged from 2.6μgkg-1day-1 (for adults) to 7.4μgkg-1day-1 (for toddlers). © 2014 Elsevier Ltd.
Yin X.,Xi'an Jiaotong University |
Zhang A.,Xi'an Jiaotong University |
Zhang H.,Xi'an Jiaotong University |
Hao L.,China JK Institute of Engineering Investigation and Design
Chinese Control Conference, CCC | Year: 2014
This paper is dedicated to the research on the digital analysis system of the power quality which is greatly deteriorated by the development of power electronic technology and the widespread application of nonlinear loads. Researchers at home and abroad have done many studies on the measurement of the power quality indicators and have proposed many measuring methods which are too complex to be used in practice. This paper proposes a hardware detection method for frequency measurement and a digital harmonic analysis method based on mixed radix fast Fourier transform (FFT) for the measurement of harmonics, and adopts a frequency-domain analysis method based on mixed radix FFT to measure the fluctuations and flicker of voltage. Compared with other measuring methods, the measuring methods proposed in this paper are simpler and more reliable, and they have fewer complex mathematical calculations and a better real-time performance. Finally, a real-time digital power quality analysis system was designed and implemented in the laboratory by using ARM processor and mixed radix FFT algorithm. After that, we tested the system by using the relay protection tester, in the laboratory, and the experimental results showed that the power quality analysis system designed satisfied the requirement of IEC61000-4-30 standard. © 2014 TCCT, CAA.
Cao Z.,Zhejiang University |
Cao Z.,Chalmers University of Technology |
Cai Y.,Zhejiang University |
Bostrom A.,Chalmers University of Technology |
Zheng J.,China JK Institute of Engineering Investigation and Design
Journal of Sound and Vibration | Year: 2012
A semi-analytical model is proposed to investigate the screening efficiency of trenches to moving-load induced ground vibrations. The ground is modeled as a fully saturated poroelastic half-space governed by Biots dynamic poroelastic theory. The trenches are obtained by placing three rectangular elastic layers with appropriate width upon the poroelastic half-space. By Helmholtz decomposition, the displacement fields of the elastic layers are decomposed into three scalar potentials. Analytical solutions are obtained based on Fourier transform and Fourier series in the transformed domain. The time-domain results are obtained by the fast Fourier transform (FFT). The different performances of trenches on a saturated poroelastic half-space and a single-phase elastic half-space to the moving load-induced ground vibration are identified. It is found that the discrepancy of the screening efficiencies between the two models becomes significant when the load speed approaches the Rayleigh wave speed of the ground surface. Also, some parametric studies for the screening efficiency of the trench on the poroelastic half-space are presented. © 2011 Elsevier Ltd. All rights reserved.
Wang J.-J.,Xi'an University of Architecture and Technology |
Deng J.-T.,China JK Institute of Engineering Investigation and Design |
Wu S.-L.,China Metallurgical Group northwest Geotechnical Engineering
Applied Mechanics and Materials | Year: 2014
Compacted loss widely used in the construction, such as embankment, dam, foundation backfill and other projects. Influenced by rainfall factors, the moisture content of compacted loess often vary so the shear strength will also changed. This paper studies the shear strength parameters of compacted loess through direct shear tests. In the dry density under the same conditions, the cohesion, internal friction angle of compacted loess decreases with the increase of water content. Summed cohesion and water content showed a quadratic parabola and internal friction angle and water content was also found quadratic parabola; further considering the effects of water content and dry density of compacted loess got shear strength formula. Shear strength formula. © (2014) Trans Tech Publications, Switzerland.
Zhang F.R.,Nanniwan Production Plant Of Yanchang Petroleum Group Coltd |
Guo A.H.,Xingzichuan Production Plant Of Yanchang Petroleum Group Coltd |
Cai H.E.,China JK institute of engineering investigation and design
Advanced Materials Research | Year: 2014
Because of the high heterogeneity, late water flooding and irregular well network, the distribution law of residual oil reserve in Chang 6 reservoir becomes much complicated. Combining the geology with dynamics of the reservoir, volumetric and formation coefficient methods are adapted to calculated the residual reserves, and then the distribution laws and controlling factors are analyzed. The results indicate that: there are still large amounts of residual reserve in main layer Chang 62 2; the residual reserve can be classified into three kinds, Class I and class II are distributed concentrative in main layer; the controlling factors include property, sedimentary facies, heterogeneity, well network controlling and geological structure and so on. Finally, according to the distribution laws and controlling factors, targeted measures are proposed. The studying results provide well foundations for improving recovery of residual oil reserves and the total recovery of the reservoir. © (2014) Trans Tech Publications, Switzerland.
Tang G.Y.,China JK Institute of Engineering Investigation and Design |
Liu Z.H.,China JK Institute of Engineering Investigation and Design |
Zheng J.G.,China JK Institute of Engineering Investigation and Design
Transit Development in Rock Mechanics-Recognition, Thinking and Innovation - Proceedings of the 3rd ISRM Young Scholars Symposium on Rock Mechanics, 2014 | Year: 2015
Coral reef calcareous rock, deposits in neritic environment, is widespread in tropical ocean area. It possesses special structure and engineering characteristics due to the sedimentary environment and short depositional history. This paper, on the basis of an actual project in East Java, discusses the basic engineering properties of coral reef rock. By way of electronic microscope scanning and mineral analysis, the results indicate that weak diagenesis of calcareous rock results in its large porosity and loose structure and, further, controls the mechanics behavior of the rock. Moreover, indoor tests and in-situ tests also show that the rock is the very soft type: its SPT blow count presents the feature of non-normal distribution with wide range of fluctuation. Besides, shear wave travels in reef rock much more slowly than it does in ordinary rocks, and the ratio of elastic wave speed and shear wave speed close to 2.0, all the phenomena showing the typical loose structure of this rock. Given plenty pores, water pressure test in borehole suggests high permeability and good connectivity of the calcareous rock, and its hydrogeological characteristics also differ greatly from that of other rocks. © 2015 Taylor & Francis Group, London.
Liu Z.-H.,China JK Institute of Engineering Investigation and Design |
Zheng J.-G.,China JK Institute of Engineering Investigation and Design
Yantu Lixue/Rock and Soil Mechanics | Year: 2013
Besides elastic strain, creep would also occurred in long-term pile stress test represented by pile immersion test in loess regions for concrete pile; and the influence of creep occurred under long-term axial stress was usually be overlooked in the past when calculating stress of pile body. But creep is a real existence, influence degree of creep and how to eliminate its effect are worth studying. Based on comparative analysis of field test data, how the concrete creep affect the analytical results of pile stress is studied; and the conclusion shows that the overlook of concrete creep will lead to wrong distribution rules of axis force and friction. A formula, which calculates axial force of pile and can eliminate the creep influence, is derived from some basic theory on creep. Some measures needing be taken in pile immersion test of loess regions to attain representative creep curve are presented; mainly include: controlling the concrete strength grade of test pile, setting calibration section near pile top and keeping concrete's temperature and moisture constant in this section and are in the same with lower pile.