bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Study of Cement-Bentonite and Cement-Based Remediation of Lead-Contaminated Soils
Authors: He Liang , Li Xiongwei , Wang Man
Published: September 2019

The mixture of bentonite and cement at a mass ratio of 2:1 (recorded as BC) was used as solidifying agent to repair lead contaminated soil, and traditional cement (PC) was used as contrast solidifying agent. The comparative test results show that the soil restoration and maintenance period reach 7 days and 28 days respectively. Compared with PC solidified soil, the pH and EC value of BC solidified soil is lower, and the pH value and EC value of 4% and 8% BC-solidified soil meet the interval value needed for vegetation growth. The dissolution of heavy metals in BC-solidified soil and PC-solidified soil decreases with the increase of the content of solidifying agent. At the same content, the dissolution of heavy metals in BC-solidified soil is lower, which indicates that the mixed material (bentonite + cement) has better effect on the fixation of heavy metals. The unconfined compressive strength of BC-solidified soil and PC-solidified soil increases with the increase of the content of solidifying agent, but compared with PC-solidified soil, the unconfined compressive strength of BC-solidified soil decreases significantly. Lower unconfined compressive strength is beneficial to the secondary development and utilization of solidified soil. The above research results show that the mixed material of bentonite and cement can effectively fix the heavy metal lead in the soil, avoid the excessive strength of the soil, and consequently cause soil hardening and influence the re-development and utilization. The mixed material is a feasible and economical repair material.
Study on the Reasonable Spacing of Post-pouring Zone for 50m Long Inverted-T Type Concrete Structure on Soft Foundation
Authors: Jiang Mengyuan , Deng Kaidi , Xu Pu , Wang Xiangrong , Qiang Sheng
Published: September 2019

There are a large number of inverted-T type concrete structures on soft soil foundation in the Yangtze River Delta area of China. Setting post-pouring belt is one of the effective methods to reduce the cracking of such structures during construction. However, there is still a lack of reference standard on how to quantify the interval between the post-pouring belts under different conditions. For this kind of structure, natural silo positions in three pouring seasons are considered, and the post-pouring belts with different spacing are set up in the base plate and pier wall. The stress development during the construction period of the concrete under different combination conditions are simulated by finite element method (FEM). The results show that under the condition of load during the construction period, the pouring blocks of the base plate on the soft foundation do not need to be provided with a post-pouring belt. While the pier wall is constrained by the base plate, the maximum tensile stress of the pier wall has a positive correlation with the maximum temperature of concrete.
Experimental Study on Impermeability of Waste Fiber Recycled Concrete
Authors: Xiaohu LI , Lei LI
Published: September 2019

The natural diffusion method was used to test the impermeability of waste fiber concrete. The influence of fiber volume rate and fiber length on the impermeability of waste fiber recycled concrete was studied. The results show that the influence of fiber length on the impermeability of recycled concrete is greater than that of fiber volume ratio. When the length of the fiber is 19mm and the volume ratio of the fiber is 0.16%, the impermeability of the specimen is the best.
Experimental study on bearing behaviour of different uplift piles
Authors: Zheng Ai-rong , Zhuge Ai-jun
Published: September 2019

Based on pile load test results of uplift bored piles for a deep-embedded underground transformer substation, the uplift behaviour of enlarged toe pile and shaft post-grouting bored piles have been studied. The loading transfer characteristics and uplift capacity improvement mechanism for the two different type uplift piles have been investigated. The research shows that post-grouting can significantly improve bored pile uplift bearing capacity. After pile shaft grouting, the interface condition between pile and soil is improved, the friction resistance of pile side is increased obviously, and the uplift bearing capacity is improved. For long uplift pile, the uplift resistance of shaft grouting bored pile is better than that of enlarged toe pile.
Experimental study on fractal characteristics of coarsegrained soil filler for high-speed railway subgrade
Authors: Wang Qiyun , Zhang Zhiliang , Lin Huaming , Wan Qian , Xu Jianwei
Published: September 2019

This paper takes coarse-grained soil filler of high-speed railway subgrade as object of study, completes a series of coarse grained soil compaction tests under different moisture content with electric heavy compaction apparatus type YX-30, and obtains the granularity fractal distribution curve with coarse-grained granularity fractal model. The result shows that coarse-grained soil filler has obvious fractal characteristics after compaction, and particle breakage fractal dimension between 2.61-2.82. With the increase of fractal dimension, the maximum dry density increases first and then decreases, and the maximum fractal dimension is under the optimum water content. The coarse-grained soil with high clay content has lower particle size and smaller fractal dimension before and after compaction. Water content and clay content are two important factors that affect the crushing of coarse-grained soil. The effect of clay content on particle size is more significant than that of clay content.
Microstructure and Mechanical Properties of Polyphosphoric Acid Modified Asphalt
Authors: Wang Zihao , Wang Lan , Li Chao , Ren Minda
Published: September 2019

Based on atomic force microscopy (AFM), PPA modified asphalt, SBS modified asphalt and PPA composite modified asphalt were tested. The microstructure and Micro-Mechanical Properties of the three modified asphalts before and after aging were analyzed with different evaluation indexes. The results show that PPA modified asphalt has good adhesion and deformation resistance, and the anti-deformation ability is more remarkable after aging, which is obviously superior to the other two kinds of modified asphalt in anti-aging performance; PPA modified asphalt and PPA modified asphalt have higher peak density, larger surface free energy and better adhesion performance, which is conducive to improving the interface adhesion between asphalt and mineral. For PPA composite modified asphalt, the addition of PPA improves the storage stability and aging resistance of SBS modified asphalt, which is superior to SBS modified asphalt in deformation resistance and cracking resistance, and has the effect of taking into account both high and low temperature performance. The micro-performance of asphalt based on AFM provides a basis for macro-performance analysis.
Experimental study on dynamic shear modulus and damping ratio of remolded loess
Authors: An Liang , JinDeng
Published: September 2019

Dynamic shear modulus and damping ratio are two important parameters to characterize the dynamic characteristics of soils. In this paper, the influence of dry density and consolidation pressure on dynamic shear modulus and damping ratio of remolded Guyuan loess is studied by resonant column tester. The results show that The maximum damping ratio decreases with the increase of dry density and consolidation confining pressure. Under the same dry density condition, the dynamic shear modulus ratio of loess increases with the increase of confining pressure; the damping ratio decreases with the increase of confining pressure; under the same confining pressure, the dynamic shear modulus ratio of loess increases with the increase of dry density, and the damping ratio decreases with the increase of dry density; the research results can provide basic information for site seismic response analysis and engineering construction in this area.
Calculation methods for reinforcement at the edge of epoxy joints of precast segmental box girders based on STM
Authors: Aimin Yuan , Xueru Zhao
Published: September 2019

To study the failure mechanism caused by diagonal crack near the joints in precast segmental box girder, a finite element model (FEM) of a standard segment of precast segmental box girder under pure bending was established. The stress field distribution for a selected segment was obtained by numerical analysis. Topological optimisation was adopted to determine the load path through the standard segment. Then, a strut-and-tie model (STM) for the standard segment under pure bending was established and verified, and calculation methods and formulae were provided for determining the reinforcement requirement at the edge of epoxy joints and at the middle of the web of the segments. Finally, a standard segment from the Fourth Nanjing Yangtze River Bridge was taken as an example to check the requirement for vertical reinforcement at the edge of the joint and horizontal reinforcement in the web, using the proposed STM. The results show that, using the STM for a standard segment when designing the reinforcement required at the edge of the joints and at the middle of the web, is acceptable, which further validates the feasibility of the proposed method.
Primary Chemical - Physical Properties of Marine Cement-Based Materials
Authors: Yan Qian , Wang Ya-jun , Liu Tao , Wu Di , Xu Yan-jie , Gan Xiao-qing , Dong Zhi-hong
Published: September 2019

The uniaxial pressure experiment was carried out on the whole-age marine cement-based materials. By analyzing this type of material, there is obvious early strength and late strength decay. The X-ray diffraction experiment was carried out on the sample before the pressure test. After the crushing, the characteristic samples were taken for multi-scale electron microscopy. The microstructure of the material was divided into the strengthening region and the weak region, and the microscopic damage process was summarized.
Comprehensive Division of Rock Mass Structure in Granite Area--Taking Tianhu Rock Mass as An Example
Authors: Li Yawei , Guo Zhejiang
Published: September 2019

In the stage of sites selection of high-level waste geological repositories, reasonable division of homogeneous zones of rock mass structure is helpful to further analyze the suitability of engineering rock mass quality and construct discontinuous fracture network model. Based on accurate measurement of surface structural planes, the surface rock mass structure in the study area is differentiated by discontinuities spacing, and the homogeneity of rock mass structure is evaluated by linear density index. The results show that the rock mass structure type in the study area is dominated by sub-blocks, and its distribution area accounts for 84% of the total area. The study area belongs to homogeneous rock mass structure with high similarity. Most of the surveying lines in the study area have high correlation and uniform joint density.
A study on the mechanical properties of cement soil added with ferronickel slag
Authors: WeiFan  , Chen Feng
Published: September 2019

Unconfined compressive strength test was employed hereby to study the effect of ferronickel slag content and mineral powder content on strength performance of cement soil. In the experiment, 0%, 10%, 20%, 30% and 40% ferronickel slag were added into the cement soil, respectively, to figure out the comparatively better content of ferronickel slag was 20%. The experiment results also indicate the addition of ferronickel slag also significantly affected the early strength of cement soil, but as the time proceeded, the strength of cement soil added with ferronickel slag fell less quickly as before.
Experimental study on the Influence of Load on Permeability Coefficient of Calcareous Sand
Authors: Shuai Wang , Xuewen Lei , Qingshan Meng , Jieli Xu , Yafei Xu , Lingfeng Xie
Published: September 2019

The permeability coefficient of calcareous sand is an important hydraulic parameter in reef engineering. The loading and permeation tests of calcareous sand and quartz sand under the same conditions were carried out by self-developed loadable sand permeability device, and the influencing factors were studied to obtain the calculation formula of the permeability coefficient of calcareous sand under load, containing void ratio e, particle gradation, permeability coefficient Ks
and the relative crushing rate B

r
proposed by Hardin. The results show that under the same load, the permeability coefficient and compressive deformation of calcareous sand decrease more than that of quartz sand, and the relative breakage rate of calcareous sand increases with the increase of load, while there is exponential correlation between its Ks
and Br
. It can be concluded that the pores of calcareous sand are compacted under load, and the granule breakage leads to gradation change, which affects the permeability coefficient of calcareous sand.
Impact response of reinforced concrete slabs in elastic half space
Authors: Yang Xiaolin , Liu Lingxiao , Wang Genhui
Published: September 2019

The analysis of the mechanical behaviour of reinforced concrete slabs on elastic foundation under impact loads is of great significance in the construction and protection of concrete pavements in airports. Based on the Elastic Half-space Foundation Model and Concrete Damage Plasticity Model, the displacement and stress fields of reinforced concrete slabs under impact loading are numerically simulated by explicit nonlinear finite element method. The result can be used to design and evaluate the safety of foundations and reinforced concrete slabs under impact loads.
The Impact of Lift Joint on the Mechanical Properties of Cemented Sand and Gravel Material
Authors: Cai Xin , Chen Jiaojiao , Li Weixin
Published: September 2019

Cemented sand and gravel (CSG) material is a new kind of geotechnical material. Layered rolling technology is always adopted in the construction of CSG dam, which inevitably creates a weak layer between adjacent CSG material layers. This weak layer is called lift joint. In order to investigate the influence of lift joint on material properties, a discrete micromechanical model of CSG material with lift joint is established based on Lattice Discrete Particle Model (LDPM). Through the three-point bending tests, compression tests and triaxial tests, the parameters for this model are calibrated. Then the impact of lift joint on mechanical properties of CSG material, including compressive, tensile, and shear behavior is studied qualitatively from mesocopic view. The result shows that the weaker the lift joint is, the lower the material strength is, the more impact of the lift joint on the mechanical properties of CSG material is.
Numerical simulation on optimization scheme of permeable hole of permeable sheet piling spur dike
Authors: Shen Shuaihui , Li Yujian , Li He , Guo Zhaojun , Zhou Zhengping , Mao Liang
Published: September 2019

Aimed at the problems about that permeable hole number and permeable hole layout of Permeable Sheet Piling Spur Dike (PSPSD) affecting the flow characteristic at spur dike area, CCHE2D flow simulation mathematical model is adopted, two dimensional flow numerical simulation is carried out for the permeable spur dike area of the physical model of the Qiman reach of the Tarim River main stream. The change law of cross section flow velocity, water level with different permeable hole number and layout are analyzed. The optimization scheme of permeable hole for the PSPSD is sought. The results show that the more number of permeable hole of the PSPSD, the higher the water level upstream of the spur dike, the lower the water level downstream of the spur dike, the smaller the flow velocity upstream and downstream of the spur dike, the better the velocity uniformity. The optimization scheme for the permeable spur dike with the best effect of flow retardation is that the number of permeable holes is 4 holes, and the spacing of permeable hole decreases gradually from the root to the head of the spur dike, which accounts for 9%, 8%, 7% and 6% of the length of the PSPSD respectively.
Experimental study on the microstructure of the lacustrine soft clay after different consolidation deformations based on SEM
Authors: Gan Jianjun
Published: September 2019

In order to study the microstrcutrue of the lacustrine soft clay under different consolidation pressures, SEM and quantitative analysis of consolidation samples were carried out through GDS consolidation undrained tests with different consolidation pressures. A different consolidation stress of 50 kPa, 100 kPa, 200 kPa, 400 kPa, 800 kPa, 1600 kPa and stress rate of 0.01 mm/min were used in this GDS test. The results show that the boundary points of primary consolidation and secondary consolidation of lacustrine soft clay are not obvious at low consolidation pressure. The consolidation pressure increases, the slope of the fractal dimension of porosity rainfall curve is larger and the reduction rate is faster, and the probability entropy is above 0.96. When the consolidation pressure is larger than 400 kPa, with the increase of the consolidation pressure, the slope of the fractal dimension value change curve of porosity slows down. The average shape coefficient increases faster when the consolidation pressure is less than 400 kPa, while the fractal dimension decreases faster. The correlation coefficients between consolidation pressure and fractal dimension value of porosity, probability entropy, average shape coefficient and fractal dimension are all greater than 0.81, showing a high correlation.
The Study of Factors on the Heat Transfer Characteristics of Interface between Cast-in-Place Concrete and Frozen Soil
Authors: Yanjun JI , Yupu HU , Tao LUO
Published: September 2019

The heat transfer characteristics of cast-in-place concrete-frozen soil contact surface directly affect the surface freezing strength of cast-in-place pile, and it is important to study the heat transfer characteristics of cast-in-place concrete-frozen soil contact surface for Pile Foundation design and construction in frozen soil area. Based on the small model pile test, a numerical analysis model is established to calculate the heat transfer characteristics during concrete poured in situ. The results show that the heat flow of 0.5h concrete and the contact surface of frozen soil increases by 381.2% when the pouring temperature raised from 5 to 30°C. The water-cement ratio increased from 0.4 to 0.6, and the heat flux of 0.5h contact surface is reduced by 23.7%. The temperature of the contact surface increased first and then decreased, and the peak is near the liquid limit of soil. When the temperature of frozen soil decreased from -1 to -3°, the temperature of the contact surface increased with the decrease of the temperature of the frozen soil. The thermal conductivity and transformation of the thermal effect of phase transition have played a decisive role. 0~1h (especially 0~0.5h) is the main time for the heat released from concrete to frozen soil.
Causes of Crack and Durability Analysis of Corroded Reinforcing Bars in Three-Orientation Pre-stressed Aqueduct with Long-span at Cold Areas
Authors: Huang Tao , Zhang Guo-xin , Li Jiang , Li Hai-feng , Cheng Heng
Published: September 2019

A large aqueduct located in the cold region of north China adopts three-orientation pre-stressed reinforced concrete structure with large span. During the construction period, after the third spring, the quality inspection of the aqueduct wall has a phenomenon of vertical long cracks, white paste, alkali corrosion and water seepage, and there is also an empty drum sound inside the wall. Using theoretical solution and numerical calculation method, the causes of cracks on the surface and the internal hollow of the aqueduct wall are analysed from the aspects of pre-stressed tension, frost heave and ambient temperature. A nonlinear finite element model with fine mesh is established to simulate the initiation of the crack and penetration process through the single hole and multiple holes frost heaving process of the bellows. Finally, the durability and hazard of aqueduct are evaluated by calculating the influence of different seam depths on the pre-stressed steel bars and ordinary steel corrosion, which provides a basis for the later crack repair protection scheme, and also provides reference for the construction and operation management of such aqueducts.
Influence of Near-field Pulse-like Ground Motion on Seismic Response of Steel-concrete Plate Composite Beam Bridges with Seismic Isolation
Authors: Yao Chunjiang , Li Runqing
Published: September 2019

For steel-concrete composite bridges, different seismic excitations are selected, and nonlinear time-history analysis method is used to study the influence of near-field seismic impulse effect on seismic response of steel-concrete plate composite beam bridges and damping effect of steel-concrete plate composite beam bridges. Under Near-Field Seismic excitation, cable-stayed seismic isolation bearings are used. The seismic responses of main girder displacement, bearing deformation, shear force and pier seismic force are compared and analysed through two directions of input. The influence of impulse earthquake on seismic response of steel-concrete composite beams with isolation bearings is studied. The seismic response of steel plate composite beam bridges is basically smaller than that of non-isolation girder bridge after the isolation bearings are laid out, and the response decreases by more than 40%. The isolation bearings have good damping effect. Therefore, under the action of impulsive ground motion, it is suggested to adopt isolation bearings, such as Cable-sliding Friction Aseismic Bearing.
The rock mechanics and acoustic emission characteristics of rock salt under tension-compression alternating
Authors: Liu Jianfeng , Liao Yilin , Deng Chaofu , Zhang Qiangxing , Li Zhicheng , Zeng Yin
Published: September 2019

In order to study the stress state and acoustic emission characteristics of salt rock energy storage during high frequency injection and production of compressed. the self-developed spring specimen limit tension and compression cycle test rock specimen fixing device based on the MTS815 Flex Test GT rock mechanics test system and acoustic emission (AE) three-dimensional positioning real-time monitoring system was used to study on mechanical characteristics and AE characteristics of pure salt rock and impurity salt rock under tension-compression alternating tests for the first time. The test results show that: (1) Under the stress path of tension-compression alternating, the tensile strength of pure salt rock is 0.95 MPa, impurity salt rock tensile strength increased by 47.37% compared with pure salt rock, axial deformation of impurity salt rock is 0.25mm, while pure salt rock is 1.40 times of it. (2) During the compression stage, AE signals with uniform distribution are produced by the effect of mutual dislocation, slip and micro-defect closure in salt rock, which has a certain end-restraint effect; In the stretching stage, the development of intercrystalline cracks is the main cause of AE signals in tensile stage, and AE signal followed hysteresis phenomenon. (3) Comparing with impurity salt rock, the cumulative ringing counts of the four compression loading and unloading stages are 3.13 times higher than impurity salt rock, AE signal of pure salt rock is weaker during tension loading and unloading, the cumulative ringing count increases slightly, a large number of acoustic emission signals accompany only the final tensile failure process. Under the condition of tension-compression alternating, AE signals of pure salt rock with the same tensile or compressive stress levels are more active than those of impurity salt rock, and the number of AE events in compression stage is larger than that in tension stage.
Applicability of HVSR in site effect of loess slope covered on mud rock
Authors: Wang Huijuan , Wang Ping , Yu Yifan , Xu Shuya , Guo Haitao , Pu Xiaowu
Published: September 2019

Taking the loess slope covered on mud rock as a research site, this study is based on theoretical foundation of the Horizontal-to-Vertical Spectral Ration(HVSR) and Sediment-to-Bedrock Spectral Ration(SBSR), site earthquake response of the loess landslide covered on mud rock calculated by use of the software FLAC3D, dynamic response of earthquakes was revealed, the simulation between HVSR and SBSR has been discussed, applicability of HVSR has been was analyzed. The results show that: The maximum horizontal displacement is found in the cliff part of the slope, the peak acceleration is the largest at the back edge of the slope and the vertical interface, as the elevation increases, the dominant frequency moves toward the lower frequency, and the higher frequency components are absorbed, the dominant frequencies obtained by HVSR spectrum ratio and SBSR spectrum ratio, and they are basically consistent with the fourier spectrum, the amplitude of HVSR and SBSR spectrum ratio are similar to the change rule of peak acceleration. Therefore, HVSR method can be applied to study the site effect of loess slope covered on mud rock
Numerical Study on Vertical and Horizontal Seepage Deformation of Silty Soil
Authors: Zhang Canhong , Wang Baotian , Yang Zhanmin , Ji Enyue
Published: September 2019

In this paper, the PFC3D fluid-solid coupling calculation module is used to simulate the seepage deformation process of silty sand under vertical and horizontal seepage. The seepage mechanism such as particle contact, flow field distribution, critical hydraulic slope and particle motion of silty sand under different seepage direction is analyzed. The numerical simulation results show that the critical hydraulic gradient of silt sand in vertical seepage is higher than the critical hydraulic gradient in horizontal seepage.
Finite Element Modeling of Asphalt Mixture Based on Image Recognition
Authors: Lv Yuejing , Jiang Yunyun , Wang Huan
Published: September 2019

This study describes a method for establishing a mechanical model of heterogeneous finite element method. With the combination of digital image recognition technology and the theory of automatic mesh generation, it is possible to establish an inhomogeneous finite element model for mechanical calculation. Firstly, the micro-structure of the two-dimensional mixture is identified. Then all the boundary points are imported into ANSYS. Finally, the finite element mesh model of the micro-structure of the asphalt mixture is obtained by using the automatic finite element mesh generation technology. Taking Marshall specimen as an example, meshing the model proves that the method is feasible.
AE Monitoring Corrosion-induced Deterioration of Reinforced Concrete Piles in The Simulated Marine Environment
Authors: Zhou Yujue , Zhou Yubao , Zheng Yonglai
Published: September 2019

An experiment study was conducted to assess the effectiveness of acoustic emission (AE) technique monitoring the corrosion-induced damage in the marine environment. Three reinforced concrete (RC) piles of 1600 mm long by 200 mm square were casted and then were exposed in a simulated marine environment to reach 5%, 10% and 20% of steel rebar mass loss respectively. Throughout the whole test period, all specimen was monitored by three AE sensors installed at two different heights of the concrete surface and at the end of the steel rebar, respectively. The AE activities were analyzed to determine corrosion-induced dterioration at different corrosion levels. Based on the finding, the effectiveness of AE technique on monitoring of RC piles of high-pile under aggressive marine environmental conditions was established.
Research on Working Status of Impervious Geomembrane along Cracks of High Membrane-Faced Rockfill Dams
Authors: Zhang Xianlei , Zhao Mengdie , Liu Yunfeng , Gu Ke , Mao Wenlong
Published: September 2019

To address the “cramp effect” caused by displacement and sediment of impervious geomembranes in the cracks along high membrane-faced rockfill dams and the problem the declining mechanical performance of the geomembranes caused by long-time tensile stress, this study developed a set of simulation devices according to the working status of impervious geomembranes in the cracks along the dam. With PVC geomembranes as the test material, this study performed tests to identify the law of decline of membrane’s mechanical performance under different conditions of deformation with the temperature of the reservoir unchanged. It used the fractional mathematical model to process the test data and concluded the law of declining mechanical indicators of the PVC geomembrane. On the basis of the test data analysis, this study divided the decline of the geomembrane’s mechanical performance under constant large deformation into two stages, proposed structural solutions to mitigate or avoid decline of mechanical performance and lengthen the service life of impervious geomembranes.
Study on Applicability of Maturity Theory to Predict Concrete Compressive Strength under Non-standard Curing Condition
Authors: Wang Liang , Wu Liqiang , Fang Chunhui
Published: September 2019

The curing temperature of the actual construction site, which has a greater impact on the concrete strength, often fails to meet the standard requirements. This paper studies the effect of curing temperature on concrete compressive strength from the perspective of maturity by designing four curing conditions including standard curing, high temperature curing in summer, low temperature curing in winter, and natural curing, using the artificial climate simulation room. The result shows that the relationship between compressive strength and maturity of concrete under the standard curing condition is basically in accordance with the hyperbolic model, which can be used to predict the compressive strength at different ages; however, when the curing temperature and the standard curing temperature are quite different, the hyperbolic model is no longer applicable; at this point, direct prediction of concrete compressive strength using maturity will lead to significant errors. Therefore, it is necessary to further establish a theoretical model of maturity that takes into consideration the effect of temperature in order to predict the compressive strength of concrete more accurately.
Study on three-point bending mechanics and acoustic emission characteristics of impure salt rocks
Authors: Liao Yilin , Liu Jianfeng , Li Zhicheng , Zhang Qiangxing , Xu Deng , Zhu Anqi
Published: September 2019

In order to study the mechanics and deformation characteristics of salt rock under bending conditions, two groups salt rocks with different impurity content were subjected to three-point bending cycle loading and unloading test and simultaneous monitoring of acoustic emission based on MTS815 Flex Test GT rock mechanics test system and acoustic emission (AE) three-dimensional positioning real-time monitoring system. The research shows that: (1) The average tensile strength of pure salt rock bending tensile is 0.88MPa, and the impure salt rock is 1.72 times of pure salt rock. The impure salt rock has better resistance to crack propagation, and COMDmax and LPDmax are 82.31% and 83.47% of the pure salt rock, respectively. (2) The bending deformation failure of salt rock can be divided into four stages of linear elastic phase, nonlinear phase, post-peak crack stability expansion stage and residual phase. (3) The three-point bending deformation of salt rock is active except for the elastic phase of the line. In general, the three-point bending deformation of the polyhalite salt rock is more active. (4) Impurities weaken the plastic deformation ability of salt rock and increase the degree of brittleness.
Analysis of earth fill hydraulic dam with varying crest length and permeability to develop correlations
Authors: Khan Muhammad Israr , Wang Shuhong , Zhangze
Published: September 2019

In this paper, an earthen dam is analysed using different soil layers having different soil properties and dimensions. Normally a slope fail when the shear strength reduces from the minimum required value which keeps it stable. Internal erosion is the main cause which causes a dam to fail and it is mainly due seepage with time. A detail analysis of a predefined dam slope is performed in different layers to check the seepage variation as well as the factor of safety. Different soil layers and properties were used such that it is investigated from a fail condition to a complete stable condition. Limit equilibrium and finite element approaches are used. Correlations for factor of safety between these two approaches are also developed. These correlations and results could be used as guidelines in any dam or slope safety calculation.
Experimental study on tension-compression alternation of fully-graded concrete under cyclic loading
Authors: Li Chunlei , Zhong Hong , Wang Haibo , Tian Juntao
Published: September 2019

Considering the reciprocating effect of seismic load and the initial compressive stress level of high arch dam, a feasible test procedure is designed by using the 15MN large dynamic material testing machine and special connection devices. The tension-compression alternating test of fully-graded concrete specimens under cyclic loading of about 5MPa compressive stress level is carried out. By means of the VIC-3D non-contact full-field strain measurement system and high-precision axial extensometer, a complete tension-compression alternating stress-strain curve of fully-graded concrete under 5 MPa compressive stress level is obtained. Based on that the tension-compression damage evolution law for this whole process of fully-graded concrete is summarized, which provides data support for studying the damage evolution of arch dams under reciprocating seismic loads.
Effect of plastic carbon fiber-biofilm technology on landscape water purification
Authors: Yang Jinhui , Luo Yi , Dai Yanghong , Yang Bin , Wang Jinsong , lei Zengjiang , Zhang Xiaoyan
Published: September 2019

In this study, a new type of plastic carbon fiber filler was applied to biofilm technology. The optimum purification conditions for eutrophic landscape water were discussed by controlling the filling amount, aeration volume and pollutant concentration. The activated sludge from the sewage treatment plant is used for aeration and filming to explore the effect of the filler on the purification effect of the landscape water body. Studies have shown that the composite filler has a good removal effect on CODcr, TN and TP in eutrophic water, and is a highly efficient new water treatment material.
Seismic Performance and Recommendation of Structural Intervention on Masonry Heritage Clock Towers: Representative Examples in Bosnia and Herzegovina
Authors: Causevic Amir , Aksamija Lemja , Rustempasic Nerman
Published: September 2019

The paper deals with selected examples of clock towers in Bosnia and Herzegovina, representing high masonry heritage buildings made of stone, and explains the approach used in their preservation and restoration. The aim of this paper is to present a specific method of conservation used on stone structures. Three clock towers from Bosnia and Herzegovina were selected as representative examples: Sarajevo Clock Tower from the 16th century is an example of well-preserved building; The Clock Tower in Gradačac, the youngest building of this type in Bosnia and Herzegovina, is in poor structural conditions and in danger of collapsing; The Clock Tower in Banja Luka, the first clock tower in Bosnia and Herzegovina, was demolished in 1993 but the reconstruction project is planned for the current year. This paper addresses the structural properties of masonry clock tower from the Ottoman period, with special attention to preservation, analysis and strengthening. These tasks are still a challenge for masonry practitioners even if significant advances in research have been made in the last decades. The dynamic behavior of the historical buildings is usually analyzed to design repair intervention solutions and retrofitting. The structural behavior is analyzed using FEM modeling to examine how far the structural defects endanger the stability of the tower. The soil properties problem under the tower has been considered. Simplified yet effective procedures have been used as well. Results of the analysis have confirmed insufficient performance of the structure under horizontal action and the need for improvement.
Wood - Polymer Composites as an Alternative to the Natural Environment
Authors: Stanaszek-Tomal Elzbieta
Published: September 2019

Along with the growing consumption of wooden and wood-based products, the amount of waste generated during both production and consumption of these products increases. These wastes constitute a rich raw material base, the appropriate use of which can significantly reduce the use of natural wood raw material. Unfortunately, a significant proportion of them, especially of post-use and wood-based origin, end up in landfills. It seems necessary to find ways to use the generated waste. One of them is to use them in the form of strengthening polymer-wood composites. Composites with a wood filler can be a competitive product for materials with an inorganic filler. The wood filler is characterized by lower cost, higher availability and definitely lower density than glass fibers. An additional advantage of composites with wood fiber is their easy recycling and a smaller amount of waste products remaining after combustion. The use of a polymer matrix provides flexibility to the composite and has a positive effect on the ability of the material to stretch under the influence of temperature. The main advantage of the matrix in the form of a polymer is also to provide the product with resistance to the effects of the external environment, especially moisture and water. The main centers for the production of polymeric and wood composites are North America and Europe. Mainly floor, wall and roof platings are created. In addition, they are used as fences, windows and doors as well as additional equipment for platforms, landscape architecture, floor materials and panels.
Water in the Architectural and Urban Planning Assumptions of Częstochowa
Authors: Tubielewicz-Michalczuk Malwina
Published: September 2019

Emerging trends in architecture and urban planning in the last decades concern the use of water as an important element creating both the image of the city, the environment and the landscape. The subject of the research is the analysis of ways of shaping contemporary public spaces on the example of water in the city and the nearest surroundings. The aim of the article is to show its impact on shaping urban development, natural and cultural environment. The subject of the publication is a systematically done research concerning architecture, architectural and landscape space of the area located above the Warta River flowing through Częstochowa as well as fountains and water reservoirs newly built in the city. The article discusses innovative solutions aimed at connecting the river and water objects of small architecture with innovative solutions of architectural designs of urban buildings created for people and friendly to the environment in which they reside.
Ecological City – Types of Wastewater Treatment Plants in Poland: The Influence of Technology on Space
Authors: Wojtowicz-Wrobel Agnieszka
Published: September 2019

Newly designed structures that provide technical services to cities gain new spatial forms. In terms of their functional and spatial structure they often also fulfil new, additional functions. This is possible thanks to, among other things, new technical and technological solutions. A departure from the typical approach based on merely associating engineering structures with an envelope of technical solutions of sorts, without care for architectural form, detail or site development, brings positive effects in terms of spatial relationships. In the case of pro-environmental structures this also has a functional dimension—oftentimes these structures start fulfilling additional functions, e.g. as a part of ecological education. Simultaneously, we can observe that some structures that provide the engineering infrastructure to the city gain a new architectural form, new site development of the space that surrounds them or are being equipped with new, additional functions, more frequently than others. Without a doubt, influence on which structures are being transformed in accordance with the abovementioned directions, and which remain on the sidelines of new spatial, architectural and functional solution, is exerted by the primary function of the structure—which is in itself obvious. However, within the group of structures with the same functions we can also observe significant differences. One example of this are wastewater treatment and water purification plants. The goal of this article is to find the answer to the following questions: is the form of a structure and its site development determined by various types of technological solutions in wastewater treatment and water purification plants—and if so, then in what manner? Furthermore, do differences in technology have an impact on the immediate surroundings of the plants and—on a wider scale—on the space of the city? The results of the study will advance knowledge concerning the dependencies between technological solutions and architectural form, as well as spatial relations within the functional and spatial structure of cities.
Experiential Learning for Seismic Protection Using Living Lab Approach in Romania
Authors: Dobre Daniela , Sorin Dragomir Claudiu , Georgescu Emil-Sever
Published: September 2019

The purpose of the research: The paper is going to present the role of seismic areas as living labs/natural laboratories for studying the behavior of buildings and of people and establishing a relationship between a research, a training-education and a knowledge dissemination. The results materialized by experiential actions to reduce negative impacts of disasters are highlighted. Methodology: Engineering learning from earthquakes, based on a long-term seismic culture, became a continuous activity based on field observation, since more than a century. On the other hand, creating earthquake disaster prevention awareness and disaster preparedness can be achieved nowadays by education and active learning addressed to all levels of population, from elder generations to the younger ones, and from usual people to the representatives of authorities. The link between these two approaches is becoming more and more necessary in the context of high local seismicity: investigating the behavior of people, while using emerging technologies (computer-generated imagery, immersive virtual reality etc.), to obtain an active individual attitude. The general concept of awareness and preparedness trends evolved. To deal with earthquake-related situations, people are taught to take measures to prevent severe earthquakes effects, but we must take a step forward to get closer to the system that includes: research knowledge, innovation, GIS and specialized software, and more importantly, the access to all of these, through public and private involvement. Conclusions: The Vrancea seismic zone of Romania, as a natural laboratory, involves us with knowledge and individual perception and attitudes and we have time for improved engineering codes, exploring and experiencing some new learning modalities, refining new policies and regulations from this field, new scenarios for implementation of disaster measures.
Fire Performance of the Thermo Insulant Facade Systems of the Buildings
Authors: Simion Adrian , Dobre Daniela , Sorin Dragomir Claudiu , Anghel Ion
Published: September 2019

The purpose of this research: The large-scale use of the external cladding systems with polystyrene thermal insulation, for rehabilitation of existing and new buildings, requires the experimental determination of the fire performance of these thermal insulating systems, both as wholes, and from the materials point of view, which they are constituted from. This study aims to present the evaluation of the fire performance of some polystyrene thermosystems and of the elements that make up these systems. Methodology: Experimental tests are carried out related to the fire behavior of polystyrene thermal insulation systems used in building renovation, in order to determine the mechanisms of flames initiation and propagation on the surface of combustible facades under natural ventilation conditions, the behavior of thermosystems in different fires scenarios and determining the fire performance of the constituent elements of these thermosystems. As a result of the performed tests, it was found that the overall performance of the thermal system against the fire action during the testing was mainly influenced by the value of the thermal load density parameter, and by the way the thermosystem is built and put into operation. The contribution of the components of the thermal system to the ignition, burning, development and propagation of flames and smoke differed on a case-by-case basis, depending on the materials used to cover the polystyrene, and the time elapsed, since they were put into operation. In the direct fire area of the fire test, temperatures above 1000 ° C have been recorded that have led, in some cases, to complete damage to the thermosystem. It is intended to establish a concordance between the parameters resulting from the tests on the facades of buildings, and those measured during the fire reaction tests of the elements which the facades were made from. This highlights the need to introduce the requirement of performing fire performance tests for building façade systems, following a harmonized testing methodology across the European Union.
Traditional wooden houses in Maringá (Brazil): ICT in planning research
Authors: Nakamura-Gonino Camila , Virtudes Ana , Silva Ricardo
Published: September 2019

In many cities, the examples of traditional architecture are being replaced by contemporary buildings, without any strategies in order to preserve a specific period of the urban and housing histories. These legacies are witnesses of particular features in terms of local communities, societies, political environments, urban morphologies or architectural languages. In this sense, this article presents the case study of the traditional wooden houses in the city of Maringá in Paraná (Brazil). There is a set of buildings which still remain among the existing urban fabric. However, every year some of them are destroyed in order to give room for new ways of designing the city. The methodological approach is based on the ICT (information and communication technologies) as a tool to study the features of these traditional wooden buildings.
Bicycle Solutions in Mountain Cities: CycloCable® in Trondheim-Norway
Authors: Matias Isabel , Virtudes Ana
Published: September 2019

With the rising of soft mobility strategies among to the decision-makers regarding the city policies, the urban designers are developing new ways of improving the bicycles using solutions considering the urban spaces. In the particular case of the mountain cities, the bicycle is still seen as a problematic way of transportation, requiring deep transformations of the urban fabric features. This paper presents the case study of the Norwegian city of Trondheim, well-known by its hills, which is an enormous success in terms of bicycle solutions not only among the locals but also among the visitors. The system is called CycloCable® and it is the first cycle lift for collective transportation which aims to help cyclists, who wish to move more easily, to overcome the sleepiest slopes in urban areas. The methodological approach is based on the literature review, in order to identify the characteristics of this system, which could be used in other mountain cities with similar features of the urban fabric.