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Journal IOP Conference Series: Earth and Environmental Science

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Kui Li
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/4/042073

Abstract:With the continuous development of social economy and the improvement of people's living standards, the construction industry has been further developed. People attach great importance to the quality of construction. In construction, safety accidents threaten the safety of construction personnel, affect the stability of construction, and definitely affect the quality of later projects. In order to ensure the sustainable development of construction projects, it is necessary to establish and improve the safety early warning system, reduce the occurrence of safety accidents, and promote the sustainable development of construction enterprises. Following is a detailed analysis of the safety early warning management in building construction, in order to provide effective reference for promoting the sustainable development of the construction industry.
Yonglai Zheng, Tanbo Pan, Yubao Zhou, Burcu Özselek
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/5/052108

Abstract:The elastic properties such as shear moduli and shear moduli of freezing and thawing soil are important parameters for analyzing the stress distribution and thaw-subsidence of freezing soil and deformation of well casing embedded in freezing soil. This paper presents elastic properties obtained by conducting laboratory testing of sand samples from the area of soil. The bending elements were used to measure the shear wave (S-wave) velocities for evaluating the shear moduli during freezing and thawing. Nine pairs of testing specimens were conditioned from 25°C to -25 °C at an interval of 5 °C for examining the temperature effects during freezing and thawing process, respectively. The test parameters included dry density (1.6,1.8,2.0 g/cm3) and moisture content(6%,9%,the saturation). Test results showed that the wave velocities and the shear moduli in all types of specimens tested exhibit sharp change when the temperature adjacent to 0 °C, likely due to non-uniform freezing point depression caused by the varying structure among specimens. The increase of dry density has positive effect on shear modulus. However, the moisture content has a dual effect on the strength of the sand soil.
Tao Huang, Guo-Xin Zhang, Jiang Li, Hai-Feng Li, Heng Cheng
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/5/052090

Abstract: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.
Jianyi Zhang, Jingshan Bo, Ping Li, Chao Shen
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/4/042070

Abstract:The probabilistic analysis method is the inevitable result of the development of engineering seismic science and adapts to the current level of people's understanding. This paper systematically summarizes the seismic damage of the engineering structures near the surface rupture zone of strong earthquakes in Yushu earthquake, Wenchuan earthquake and Jiji earthquake in recent years. According to the quantitative relationship between building damage index and distance, probability analysis results of the setback distance is given. This result is easy to popularize and apply, and lays a foundation for probabilistic risk analysis of buildings close to the surface rupture zone of strong earthquakes.
Yuejing Lv, Yunyun Jiang, Huan Wang
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/5/052103

Abstract: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.
Anqi Wang, Xiaolin Yang
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/5/052055

Abstract:In order to study the influence of freeze-thaw cycles on the bond-slip relationship between concrete and steel bars, uniaxial compression and pull-out tests were carried out on concrete cubes experiencing 0, 25, 50 and 75 freeze-thaw cycles according to the existing stress models and the related concepts of ultimate bond force after freeze-thaw cycles. The bond stress and slip law between freeze-thaw concrete and steel bar are obtained. At the same time, the bond slip curve can be fitted by Bigaussian function. The results showed that with the increase of freeze-thaw times, the micro-pore structure on the surface and inside of concrete expands, the uniaxial compressive strength decreases, and the bond stress and slip between steel bar and concrete decrease.
Shunwen Ji, Tianhan Hu
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/5/052056

Abstract:Concrete is a complex multiphase composite. Along with the hydration reaction, the thermal and mechanical properties of concrete continue to increase, resulting in deformations such as temperature, autogenous volume and shrinkage, and stress and creep after being restrained by themselves and externally, further cracks are formed. Through finite element simulation, the key parts of temperature control and crack prevention of concrete dam can be predicted, and targeted crack prevention measures can be proposed. Therefore based on BIM technology and combined with simulation results, this paper conducts real-time monitoring of concrete temperature and stress during construction. Through comparison and inversion analysis, the whole process dynamic management of temperature and stress during dam construction period is implemented, and temperature control measures are optimized in real time to realize the whole process control of temperature control and crack prevention of concrete dam.
Liu Kui-Zhou, Huang De-Rui, Jiang Wei, Shen Yu-Jie, Li Yang
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/5/052061

Abstract:In order to study the mechanical properties of concrete materials in the normal operation phase of LNG tanks, the longitudinal strain of the loading direction and the transverse strain of the vertical loading at the corresponding temperature were measured by using the resistance strain gauge test technique. The elasticity of the mortar block and stone in the ultra-low temperature environment was studied. Modulus, Poisson's ratio and shear modulus are respectively related to temperature. The results show that the Poisson's ratio of stone and mortar is not obvious with temperature, which can be considered as a fixed value; the elastic modulus and shear modulus of mortar block increase linearly with the decrease of temperature, and the elastic modulus and shear modulus of stone The temperature decrease is a quadratic function relationship of decreasing first and then increasing. The elastic modulus and shear modulus of the stone are all the smallest at around -60 °C. It is concluded that the concrete material has better mechanical properties than the normal temperature environment in the ultra-low temperature environment, and can be used to further improve the design and construction of the LNG tank.
Qiyun Wang, Zhiliang Zhang, Huaming Lin, Qian Wan, Jianwei Xu
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/5/052024

Abstract: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.
Chang Wu, Guiwu Huang, Jinwei Ding
IOP Conference Series: Earth and Environmental Science, Volume 304; doi:10.1088/1755-1315/304/4/042029

Abstract:In order to analyse the influence of continuous impact load and the stiffness of the welded hollow sphere joints on the impact resistance of the welded hollow sphere joints and verify the reliability of the generalized finite element software ANSYS/LS-DYNA precise modeling analysis of impact problems, two sets of the welded hollow sphere joints models with diameters of 80mm and 100mm were designed. The experimental results of three deformation stages (elastic, elastic-plastic and plastic deformation stages) in 18 working conditions of the two groups of models were analyzed. From the deformation mode, the acceleration and displacement of the sphere joint, the strain of the model member and the finite element simulation results, it is found that the test results and the finite element simulation are highly consistent. At the same time, the results show that the higher the stiffness of the welded hollow sphere joints, the better impact resistance of the joints. The continuity of the load has a great weakening effect on the impact resistance of the elastic-plastic and plastic deformation stages of the joints.
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