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July 30,2014
Volume 7,Issue 14
Pages -
Subject Area:Hydraulic Machinery,Hydraulic Structures,Basic Subject of Civil and Architectural Engineering, Engineering Mathematics, Engineering Mechanics,Civil Construction Structure,Foundation Engineering

Title: Msoscopic damage characteristic research of argillaceous sandstone under dry-wet cycles

Authors: LIU Xinrong, ZHANG Liang
PP: 1461-1468
Abstract: A series of uniaxial compression simulation tests on sandstone under dry-wet cycle have been carried out using particle flow code (PFC) soft. The corresponding complete stress-strain curves are obtained and characteristics of deformation and failure are analyzed. Compared with the dry specimens, elastic modulus, uniaxial compressive strengths of the specimens under “dry-saturation” cycling are all decreased to some degree. The effects of dry-wet cycle on rock strength and deformation are analyzed by theories of darnage mechanics. Through introducing the volumetric change caused by rock dilatancy to the darnage variable, the evolution equation of darnage of rock meeting with water is established, which is closely related to rock stress state. The results show that by microscopic analysis of the sandstone damage, this research can actually provide a reference value for the macro works.
Keywords: other subject of basic science of water conservancy project; dry-wet cycle; argillaceous sandstone; damage; particle flow code

Title: Research on transient process of pumping station system with tunnel

Authors: TAO Dan, WANG Ling, WANG Fujun
PP: 1454-1460
Abstract: In this paper, two algorighms using to deal with the flow interruption in the hydraulic transition process of a water transfer project with tunnel are investigated. The results show that both virtual flow method (VFM) and approximation flow method (AFM) can be used in the evaluation of open channel flow with flow interruption. VFM conducts high precision results, but needs reasonable initial flow rate input. AFM is simple in calculation, but sometimes can not supply characteristics of hydraulic transients for some special positions. For a given engineering example, the hydraulic transient processes of tunnel under pump start and power failure conditions are analysed.
Keywords: hydraulic machinery; tunnel; hydraulic transient; flow interruption; algorithm

Title: Experimental analysis of the shear strength and the deformation characteristics of cement sand and gravel

Authors: CAI Xin, YANG Jie, GUO Xingwen
PP: 1448-1453
Abstract: The present work is concerned with investigating the shear strength and the deformation characteristics of cement sand and gravel based on a large number of triaxial test results of such material from three different aspects, including Mohr envelope characteristics of the peak strength, Mohr-Coulomb envelope characteristics of residual strength and the influence of cement content and confining pressure on secant modulus. It has been found that the shear strength of cement sand and gravel meet Mohr-Coulomb criterion; the secant modulus of cement sand and gravel increase with confining pressure increasing. The influence of cement content increases on the modulus of cement sand and gravel is ignored, but on the secant modulus is significant.
Keywords: hydraulic structure; shear strength characteristic; deformation characteristic; triaxial test; cement sand and gravel

Title: Analysis of frequency response characteristics for air float structure

Authors: LIU Xianqing, BIE Mingjuan
PP: 1440-1447
Abstract: In this paper, based on three dimensional potential flow theory and MOSES software, the frequency response characteristics of air float structure in different subdivisions,different drafts and different water depths are analyzed taking rectangular type air float structure as an example. Analysis results show that the effects of the change of subdivision and draft on the response amplitude operator (RAO) of surge for air float structure are not obvious. With the subdivision increasing and draft decreasing, the maximum amplitude frequency of heave and pitch for air float structure increases. When the disturbance frequency is greater than a certain value, the effect of water depth to RAO can be neglected.When the disturbance frequency is less than a certain value，the increase of surge is far greater than heave and pitch as the water depth decreases because of the shallow water effect.
Keywords: ocean engineering; air floating structure; MOSES; response amplitude operator; draft; water depth

Title: Vertical distribution characteristics of soil heavy metals under sewage irrigation for different decades in Luancheng, Hebei province

Authors: DI Zhijiao, LIAN Jingjing, JIN Menggui
PP: 1430-1439
Abstract: Based on field investigation, soil sampling and analysis, the contents of Pb, Cr, Cd, As, Cu and Zn in farmland soils and their vertical distribution in typical sewage irrigation areas for different history (18 years, 50 years and non-sewage) in Loudi, Luancheng of Hebei province were studied. The results showed that for alkaline loam or sandy loam, the contents of total Cd, Pb, Cu and Zn in top soils increased with time of sewage irrigation, but not evident for As and Cr. For the sites of WS2 (18 years) and WS3 (50 years), the total contents of Pb, Cd, Cu and Zn were increased significantly for the layer of 0-20 cm, and increased less for the layer of 20-40 cm, but not increased evidently for the layers of 40-200 cm. The contents of Cd, Pb, Cu and Zn in sewage irrigated soil were largely influenced by sewage irrigation and the content of Cr might come from soil parent material and sewage irrigation, while the content of As was mainly controlled by soil parent material.
Keywords: water resources protection; sewage irrigation; heavy metal of soil; distributing characteristics

Title: Dynamic characteristic study of vertical hyporheic flux based on a heat tracing method

Authors: SU Xiaoru, SHU Longcang, LU Chengpeng, LIU Bo, ZHU Jingsi, WU Guangdong
PP: 1421-1429
Abstract: We monitored the vertical stream temperature time series at various depths in Dawen river, Jining city, Shandong province, and calculated the instantaneous hyporheic flux through the analytical solution of one-dimensional heat transport governing equation and the dynamic harmonic regression (DHR) signal processing technology, by which the temperature fluctuation amplitude attenuation and phase delay could be obtained. Then we analyzed the dynamic characteristics and vertical distribution of hyporheic flux. The tests showed that the surface water and air temperature fluctuated approximately sinusoidally while the groundwater temperature maintained stable over time. During the monitoring period, the hyporheic flux fluctuated significantly, it ranged from 97 L/(m2穌) to 321 L/(m2穌), and the hyporheic flux between different depths firstly decreased and then increased. This vertical distribution existed differences with variation time.
Keywords: water resources protection; hyporheic flux; streambed temperature; heat transport equation; heterogeneity characteristic

Title: Design and development of a test bench for heat and mass transfer process in vacuum conditions

Authors: XIE Xiaoyun, JIANG Yi, WANG Sheng, LI Jingyuan, ZHENG Shuying, ZHU Chaoyi, WU Jianfeng
PP: 1410-1420
Abstract: A novel test bench for vacuum heat and mass transfer processes is set up and now is passed strict multi-step leak detection and the system regulating process. In this paper, the principle and structure and running performance including the vacuum performance, control performance, stable operation performance, measuring precision, measurement performance etc are reported. Now the test bench is put into use successfully. As the first test bench for components of absorption heat pumps under vacuum conditions, the general basic experimental platform can be applied to all kinds of relevant heat and mass transfer phenomenon such as evaporation and condensation of water, absorption and generation of the lithium bromide (LiBr) solution, and also the development of new machines.
Keywords: rentilation and air conditioning engineering; absorption heat pump; vacuum condition; test bench; vacuum performance; control performance

Title: Experimental research of the influence of clothing on human thermal response

Authors: XIANG Mei, LIU Hong, LEI Danni
PP: 1402-1409
Abstract: Clothing is an important factor affecting human thermal comfort. In order to study the impact of the way of clothing regulatory on thermal response of human, a climate chamber was used to create condition of three temperature levels from neutral environment to the cold, and 3 typical ways of dressing were selected for each temperature level (basic clothing and addition of clothing with the same clothing insulation crossing the upper and under part of body) to carry out the human experiment of response of the way of dressing to thermal comfort. The results showed that thermal comfort could be obviously improved by increasing clothing of the upper or under part of body at 22℃. The weight of clothing insulation of upper part of body was larger than that of the under part at 16℃. The weight of clothing insulation of under part of body was larger than that of the upper part at 10℃. These results suggested that there were some defects in the way of calculation of direct superposition of single clothing insulation defined in the international standard in the application of index evaluating thermal comfort ［such as predicted mean vote (PMV)］, thus modifications should be considered for different thermal environments.
Keywords: rentilation and air conditioning engineering; clothing; air temperature; thermal sensation; skin temperature; predicted mean vote

Title: PFC3D simulation of direct shear test of granular geo-materials

Authors: JIN Bo, ZHAO Honghua
PP: 1393-1401
Abstract: Particle flow code 3D (PFC3D) software was used to simulate the direct shear test of granular geo-materials. By adjusting parameters in the simulation, it performed a series of direct shear test. Testing data was used to analyze the mechanical properties of geo-materials. This paper investigated the variation of shear stress versus shear displacement, the vertical displacement versus shear displacement under the action of different normal stresses, and the variation of energy during the shear process. In the simulation, the effects of grain size, void ratio, stiffness, and friction coefficient were considered. It was found that strain energy and friction energy varied linearly with normal stress, the strength of granular materials had a polynomial relationship with the average particle diameter, peak shear stress increased firstly and then dropped with increasing void ratios, and shear strength had a positive relationship with the particle’s stiffness.
Keywords: busic subject of civil building engineering; granular geo-material; discrete element method; particle flow code 3D; direct shear test

Title: Damage analysis under ground motion action based on wavelet packet energy

Authors: ZHOU Chengjie
PP: 1386-1392
Abstract: Aiming at structural seismic performance evaluation, wavelet packet energy was used to construct seismic damage assessment indicator summation of energy ratio variation (SERV). A 3D steel frame finite element model was established by ANSYS program. Then, curves of PGA-SERV was solved through elastic-plastic time history analysis of the finite element model. The numerical example showed that SERV could make assessment on the structural damage and SERV increased with damage degree. Damage conditions such as slight damage, severe damage and collapse could be obtained by PGA-SERV curves, the conclusions could be used for performance-based anti-seismic design. In addition, the rationality of the conclusions was verified by the PUSHOVER analysis and material damage analysis.
Keywords: civil building structure; damage analysis; structural seismic damage model; wavelet packet; elastic-plastic time-history analysis

Title: Preliminary study on the seismic standard deviation spectra and response spectra

Authors: PENG Lingyun, HUANG Ji
PP: 1379-1385
Abstract: In this paper, the concept of seismic standard deviation spectra is proposed, which is the spectra curve with the characterization of the peak response value of a structure of single degree of freedom input by a stochastic seismic process changing with the period of this single degree of freedom (SDOF) structure. The standard deviation spectra can be used to computer structural standard deviation response, based on the uniform modulation model of earthquake process and the Monte Carlo method, the statistical analysis on the relationship between standard deviation spectra and response spectra of the acceleration records attained during Wenchuan earthquake and Chichi earthquake is performed. The results indicate that the correlation between standard deviation spectra and response spectra is very high, and the statistical converse formula from response spectra to standard deviation is given out. It can be used to establish the standard deviation spectra according to the code-response spectra curves, and attain the structural standard deviation response by mode decomposition of standard deviation spectrum method similar to mode decomposition of response spectrum method.
Keywords: civil building structure; earthquake ground motion; standard deviation spectra; response spectra; mode decomposition

Title: Study on the flexural behavior of BFRP-plate strengthened beams

Authors: LÜ Qingfang, QIN Jihong, ZHU Ran
PP: 1371-1378
Abstract: Flexural behavior of basalt fiber reinforced plastics (BFRP) composite bamboo beams is tested with taking the size effect and number of BFRP-plate layers into consideration. The results illustrate that the BFRP-plates enhances the stiffness and ductility of bamboo beam, proving that BFRP plates undertakes a portion of tension in the tensile region. With layers of BFRP plates increasing, the enhancing effects is more significant. However, strengthening effects declines with the aspect ratio increasing of bamboo beam.
Keywords: civil building structure; basalt fiber reinforced plastics-plate; strengthen; mechanical property

Title: Influence of wall thickness of large diameter circular diaphragm wall on the horizontal displacement of foundation pit

Authors: LIU Hefeng, ZHOU Zhonghua, ZHU Junchang, WU Tao
PP: 1363-1370
Abstract: By ANSYS software, the two models of circular diaphragm walls which had or not had ring beam were established. By using the method of 3D spring-slab, the variation of maximum horizontal displacement of the foundation pit was studied when the thickness of these large diameter circular diaphragm walls changed. The calculation results showed that increasing the thickness of the wall could effectively reduce the horizontal displacement of foundation pit when the thickness was thin. But when the thickness exceeded a certain value, the horizontal displacement would not be reduced significantly, if the thickness of the wall continued to be increased. Through further analysis of the deformation results, the functional relations of wall thickness-maximum horizontal displacement and wall thickness-the rate of decrease of displacement were got. This research could provide some references for taking value of the wall thickness.
Keywords: foundation engineering; geotechnical engineering; circular diaphragm wall; thickness of diaphragm wall; 3D spring-slab method; horizontal displacement

Title: Environment vibration measurement and analysis of the underground structure caused by the inter-city railway

Authors: WANG Wenlong, MA Kunquan
PP: 1354-1362
Abstract: This paper is based on the measurement of a underground structure of a railway station. By analysis of the vibration data, this paper gets the regularity of propagation and attenuation of the environment vibration. In addition, it discusses the index of environment vibration by the 1/3 octave band method, and gives the evaluation result according to the national relevant code.
Keywords: underground structure; environment vibration; inter-city railway; 1/3 octave band

Title: Review on the technologies of lunar regolith excavation

Authors: BAI Yun, ZHENG Yanlong, KOU Lei, ZACNY Kris
PP: 1345-1353
Abstract: This paper briefly presents the backgrounds, purposes and significance of lunar excavation. The major challenges of the lunar environment and lunar regolith posed on excavation are introduced. Then, the recent research development abroad on excavation technologies such as conventional machinery, explosive and compressed air are discussed in detail. The authors suggest that the conventional machinery can’t overcome the high adhesion and abrasion of the regolith and the use of explosive in early lunar exploring is impractical. The pneumatic technology may be first used for its readily adaption to the lunar environment. Finally, the authors suggest to study the moving properties of the regolith under pneumatic conditions through physical experiments and numerical simulation in the future.
Keywords: underground engineering; resource utilization; review; lunar regolith excavation; lunar environment; pneumatics

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