Ebook: Hydraulic and Civil Engineering Technology VI
New technologies, such as improved testing and physical modeling methods, together with numerical studies and other novel techniques, have led to many developments in the fields of hydraulic and civil engineering in recent years.
This book presents proceedings from HCET 2021, the 6th International Technical Conference on Frontiers of Hydraulic and Civil Engineering Technology, held in Sanya, China, on 28 and 29 August 2021. The conference highlighted the latest advances, innovations and applications in the fields of hydraulic and civil engineering, and served as a platform to promote and celebrate interdisciplinary study. The book contains 89 papers, selected from 178 contributions and divided into 4 sections: Modern Civil Engineering; Water and Hydraulic Engineering; Environment Engineering and Sciences; and Transdisciplinary Engineering and Technology. Topics covered involve both theoretical and practical knowledge and understanding, primarily in the areas of hydraulics and water resource engineering, civil engineering, environmental engineering and sciences, transportation engineering, coastal and ocean engineering and transdisciplinary engineering and technology.
The book, which presents a wealth of exciting ideas that will open novel research directions and foster multidisciplinary collaboration among specialists in various fields, will be of interest to all academics, researchers, practitioners and policymakers seeking to understand and tackle civil and hydraulic engineering challenges by adopting appropriate, sustainable, solutions.
The 6th International Technical Conference on Frontiers of Hydraulic and Civil Engineering Technology (HCET 2021) was held in Sanya on 28–29 August 2021. Organized by the China University of Geosciences and Henan Polytechnic University, China, with Prof. Andreas Malcherek from the Bundeswehr University Munich, Germany, Dr. Yizi Shang, China Institute of Water Resources, China, and Prof. Shiqiang Xu, Chang’an University, China as the keynote speakers, HCET 2021 highlights the latest advances, innovations, and applications in the field of hydraulic and civil engineering. Since its founding in 2013, HCET has consistently been a major event to promote and celebrate interdisciplinary study.
This book presents the proceedings of HCET 2021, and contains 89 papers selected from 178 contributions. The topics discussed revolve around both theoretical and practical knowledge and understanding, primarily in the areas of hydraulics and water resource engineering, civil engineering, environmental engineering and sciences, transportation engineering, coastal and ocean engineering and transdisciplinary engineering and technology. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster multidisciplinary collaboration among specialists in different fields.
Our sincere appreciation goes to the supporting institutions of HCET2021, the China Communications Construction Co. Ltd., the University of Texas at Arlington, the China Railway Major Bridge Engineering Group Co. Ltd. (MBEC), and Goethe University, Frankfurt. We would also like to thank our keynote speakers, as well as all members of the Technical Program Committee for their work on the international peer- review process. Most importantly, our special thanks go to IOS Press and all those publishing staff who have assisted with the publication of this volume as part of the series: Advances in Transdisciplinary Engineering.
This book of proceedings will be useful to all those academics, researchers, practitioners and policymakers seeking to understand and tackle challenges in an efficient manner by adopting appropriate, sustainable, civil engineering and hydraulic engineering solutions. The newly developed testing methodologies, physical modeling methods, numerical studies, and the other novel techniques discussed in this book will prove useful to researchers and practitioners across the globe. We thank all who attended and contributed to HCET 2021. Finally, we sincerely hope that HCET2021 will prove to be a forum for excellent discussions that put forward new ideas and promote collaborative research in the future.
The Program Committee of HCET2021
Reasonable evaluation of the bond performance between steel bars and concrete has important theoretical and practical value for reinforced concrete structural design and seismic analysis. The stress (τ) – strain (ε) formula is corrected based on a pull-out test, and the load (F) – deflection (w) curves are analyzed according to the change of stiffness before and after crack appearance based on a beam test, and new estimation formulas are given. At the same time, the bond properties are compared between all-lightweight shale ceramsite concrete (ALWSCC) and normal weight concrete (NWC). The results show that the bond property of ALWSCC is better than NWC. The bond stresses of pull-out specimens and beam specimens are the same or similar under equal conditions, but the ultimate load (F0) of the former is about 3.66 times that of the latter, the peak slip (S0) of the latter is 4.80 times that of the former, and the latter has significant splitting or pull-out failure characteristics. The peak slip (S0) in this paper is larger than that in the related literature, where the pull-out specimens are no more than 10 mm, and are generally less than 2 mm, while the beam specimens are not more than 3 mm, with the others generally around 1 mm. The research results have reference values and guiding significance for similar experimental research and engineering practice.
The cutting relationship and development degree of structural plane control the instability mode and scale of rock slope. The trajectory of rock mass after instability is an important basis for the design of dangerous rock prevention. The back slope of a residential area was investigated in this paper. Based on the survey data of the field structure surfaces, the possible instability mode of the slope rock mass was analyzed by using the stereographic projection method. The shear strength parameters of the rock mass were inverted through the investigation of dangerous rock mass. Finally, ANSYS/LS-DYNA was used to simulate the dangerous rock mass motion trajectory. This study provides a reference for the analysis of the instability process of single rock.
Based on a subway station project, this paper puts forward the risk factors in the process of subway construction. The analytic hierarchy process (AHP) is used to establish the risk factor model of metro station. Establishes the risk judgment matrix at all levels by combining the results of expert investigation method. By evaluating the risk factors of the subway station, the weight values of the above risk factors are calculated and sorted. As a result, the risk management system of subway station is put forward.The research results of this method provide a theoretical basis for the project managers to determine the risk factors, and lay a foundation for the smooth progress of the subway station construction project.
In seasonal frozen soil area, the engineering problems caused by the excessive moisture content of the subgrade soil are widespread. In view of this phenomenon, author proposes to employ a new type of research and development of the seepage drainage geogrid (SDG) to cool and drain the soil. Through indoor model test, after two freeze-thaw cycles, the experimental comparison of the size and laying method of various SDG was carried out. The test result shows that the model with a natural grit layer has the most drainage effect. While, the model contains two layers of interconnected grilles has the best cooling effect. The indoor model test is simulated by accurate numerical simulation. The simulation results are compared with the indoor test results. The fitting results of the two results are very high, which provides theoretical support and data guarantee for the application of seepage drainage grille to strengthen the roadbed in the cold road.
Through three-dimensional nonlinear finite element analysis, the punching failure’s bearing mechanism of the independent foundation under column whose slab is the size of 0.8m×0.8m×0.3m is obtained. The transfer mechanism of the foundation is spatial strut-and-tie model, where the reinforcements located in the link ranges between each adjacent corner of the slab are represented by ties, and the concrete distributed in the link ranges from the column bottom to four corners of the slab bottom are represented by struts. The indication of punching failure is that the concrete at the two ends of the struts reaches the shear-compression failure strength, and the punching cone is punched out relative to the slab, which has distinct punching failure features. A new spatial strut-and-tie model composed of four ties and four struts is proposed on the basis of clear bearing mechanism, which provides a new idea for the calculation of the punching bearing capacity of the independent foundation under column.
Groundwater vulnerability assessment is a basic work for groundwater exploitation and protection. The Chaoyang district of Beijing was selected and investigated in this study. Groundwater vulnerability index system in Chaoyang district was constructed based on hydrogeological settings of local region, the human influence and the DRASTIC model. The comprehensive vulnerability assessment was carried out with weights of 0.4 and 0.6 for the intrinsic vulnerability and the specific vulnerability, respectively. In this study, total 9 hydrogeological parameters were considered, and the diagram of groundwater vulnerability assessment results in Chaoyang District was obtained by using DRASTIC index and overlay weighted method. The groundwater quality is poor in the southwest of Chaoyang District. The correlation analysis between total hardness, total dissolved solids and vulnerability results was carried out, and the correlation results were 06 and 0.7, respectively. The area with high groundwater vulnerability is also the regions with serious groundwater pollution, indicating that the assessment results are objective and reasonable, which can provide prevention and control of groundwater reference for the management department in the future, so as to reduce the risk of pollution.
As the most widely used construction material, concrete has the characteristics of good compressive performance. The compressive strength of concrete is the most important performance index. However, the compressive strength of concrete measured is generally based on the standard curing period for 28 d. Its period for detection is long. Therefore, it is necessary to study a fast and effective detection method. This paper mainly introduces the experimental method of microwave curing concrete and the relationship between concrete strength values of curing specimens using microwave and standard methods. The experimental results show that concrete specimens exposed to accelerated curing condition under microwave irradiation can increase the strength quickly within a shorter time period depending upon the procedure used in this work. By analysing experimental data, a model of concrete strength at age of 28 d using microwave curing and standard curing methods is established, which can early estimate compressive strength of concrete and provide a quick method for measuring the strength in the field.
Taking the viaduct project of the main road bridge of Fushi road between Jinding Street station and Jinanqiao Station of line 11 of Beijing subway as the background, due to geological reasons, the length of the pile of the main road bridge of Fushi road is 60m to the west of Xin’an road in the north, the pile length of the bridge east of North Xin’an road is 21.5m, and line 11 of Beijing subway passes between two piles of unequal length. This paper simulates the whole construction process with the method of numerical analysis, analyzes the causes of the deformation of the bridge piles by calculation, puts forward the measures of grouting reinforcement in the whole section, sums up the deformation rules of the unequal length bridge piles, and puts forward the deformation control values, in order to ensure the safety of Rail Transit Construction, for the follow-up similar projects to provide a basis and reference.
Based on the Xigeda clay rock exposed in the back mountain of Nanshan Villa in Xichang City, the microstructure changes of Xigeda clay rock before and after water softening were studied by scanning electron microscope and image recognition of PCAS software. The results show that: (1) the clay rock of Xigeda group has flake and layered micro structural characteristics, and the surface of aggregates in natural state has honeycomb characteristics. After water softening, the aggregate particles decompose, the average size of particles becomes smaller, the honeycomb characteristics disappear, and the surface contours of particles become smooth and round. (2) With the increase of water saturation time, the number of aggregate particles and pores increases, the porosity decreases in advance and increases in the later stage. (3) Micro structural changes of the clay rock in Xigeda formation have two stages, in the first stage, the aggregates decompose and the produced fine granular clays fill the original pores, resulting in the decrease of porosity.In the second stage, the fine clay particles further soften, decompose and lose in the water, the porosity increases suddenly.
In this paper, the fracture behavior of concrete with different initial notch lengths after freeze-thaw action was studied by using three-point bending test. Then, based on the boundary effect model, the parameters indicating the material discontinuity and inhomogeneity were introduced, and the maximum fracture load of the beam was used to determine the real tensile strength and fracture toughness of concrete under different freeze-thaw cycles. Results show that the tensile strength and fracture toughness of concrete are obviously reduced. Compared with the control specimens under indoor condition, the fracture parameters are reduced by more than 38% when the number of freeze-thaw cycles reached 75 times. In this paper, the tensile strength obtained based on the boundary effect model is significantly higher than the splitting tensile strength of concrete due to the incorporation of the discontinuity and non-uniformity of materials, and can more accurately reflect the deterioration and damage degree of concrete after freeze-thaw action.
In order to study the mechanism of water damage of an asphalt pavement, the FLAC3D program was adopted to model and analyze the mechanical response of a saturated asphalt pavement under instantaneous vehicle load. The results show that the horizontal stress, vertical stress and shear stress of an asphalt concrete pavement increase with the increase of instantaneous load. The surfaces of asphalt pavement structural layers are most vulnerable to damage. The horizontal stress, vertical stress and shear stress decrease sharply with the instantaneous dynamic load decreasing to zero. The horizontal stress reaches maximum value at the interface between the base and the large stone porous mixture (LSPM) layer, while the maximum vertical and shear stresses occur on the surface layer of the saturated asphalt pavement. The deformation decreases almost linearly from the surface of the asphalt pavement to the subgrade, and the pore water pressure was little influenced by the transient load.
The wet slime tailing pond formed during the production of accumulated bauxite is a source of artificial debris flow hazard with high potential energy. In order to explore the effectiveness of solidification technology in processing bauxite slime, experimental study was conducted on the strength characteristics of cement-solidified slime with bauxite slime as the test object, so as to investigate the impact of cement contents and curing ages on the compressive strength of cement-solidified slime. According to the test results, the strength and deformation characteristics of solidified slime are related to the cement content, and the higher the cement admixed amount, the greater the compressive strength of solidified slime; the cement-solidified slime samples are subject to brittle failure, and with the increase of strain, the stress first rises to its peak and then decreases rapidly. The findings may serve as reference in processing bauxite slime.
Traditional disposal of the high-water content slime from the beneficiating and washing of the bauxite mine requires lots of land and a long time to consolidate, which has attracted a wide range of environmental and social concerns. High-speed centrifugal test was carried out to investigate the water property and composition of high-water content bauxite washing mud. Test results indicated that the bound water content ranged from 29.7% to 31.4%, free water content ranged from 250.6% to 252.3%. The bound water accounted for only 11%, while the free water accounted for about 89% of total water content. A series of model tests were conducted to study the slurry-water separation property of high-water content bauxite mine slime. Experiments showed that controlling the vacuum load application process can effectively inhibit the formation of low-permeability stratum around the drainage body. The final settlement increased by 31.5% and the amount of water discharge increased by 39.52% compared with the conventional vacuum preloading method. Moreover, the water content may decrease from 281.9% to 53.6% within 60 hours with the increase of density of drainage body under the controlled vacuum load application process.
Deep cement mixing is an effective ground stabilization technique to control the ground movement on sand areas, and most of the projects have the problem of seepage. The cement slurry is in a fluid state before the initial setting time, the seepage may affect the diffusion process of cement slurry during this period. A hydro-mechanical approach is proposed to investigate the interaction between the seepage and the strength of cement-stabilized sand. The diffusion of the cement slurry under seepage is considered in this study and the diffusion process is simulated by the finite element method. According to the cement concentration at the end of the diffusion process, the strength of cement-stabilized sand can be predicted by combining an empirical formula. Simulation results examine that the existence of seepage and cracks can enhance the non-uniform diffusion process of cement slurry, and the actual strength distribution of the deep cement-mixed sand is far from the ideal state. This indicates that the influence of seepage on the strength of cement-stabilized sand should be considered in the design of projects.
The effect of wetting-drying cycles on deformation characteristics of an unsaturated clay model slope is investigated in this study. The model slope was compacted using kaolin clay mixed with thirty percent of fine sand. The deformations of slope were measured using particle image velocimetry (PIV) technique. The test results revealed that the model slope deforms mainly within a depth of 300 mm and the displacements of soil mass are nearly perpendicular to slope surface in the first two cycles. Such displacements, however, vanish gradually in the subsequent cycles. On the other hand, the magnitude of displacement along slope surface increases with the number of wetting-drying cycles. The depth affected by wetting-drying cycles increases gradually with the number of wetting-drying cycles and becomes stable finally.
In order to explore the polymerization mechanism of granite residual soil, geopolymer containing fly ash, various particle groups, granite residual soil and their composites were prepared with different materials. Sodium hydroxide and sodium silicate are used as alkali activators. In this paper, the compressive strength of geopolymer was studied. The mineral composition and microstructure were tested and analyzed by X-ray diffraction and scanning electron microscope. The results show that geopolymerization can only occur in fine particles due to the presence of amorphous aluminosilicate in granite residual soil. The zeolite phase transition of low polymer in fine-grained reaction is beneficial to enhance the integrity of the sample and improve its compressive strength. The addition of fly ash can accelerate the geopolymerization rate and improve the strength of fine geopolymer, but it can inhibit the occurrence of zeolite phase transformation.
In order to explore the distribution of soil pressure on the side of the pile and the bending moment of the pile body during the excavation and pile loading stages of the H-shaped prestressed concrete piles, three groups of indoor scaled model tests with prestressed rectangular piles and with or without prestressed H-shaped piles were carried out, and the test results shows that the lateral earth pressure on both sides of the sheet pile has the same trend as the static earth pressure calculation value when it is not excavated, but the measured earth pressure at different depths is always lower than the static earth pressure calculation value; in the excavation stage, the H-shaped prestressed pile lateral soil pressure on the side of the pile excavation is less than that of the rectangular sheet pile and the unprestressed H-typed pile.
To study the service status of the tunnel structure near the station, a disease detection of Metro Line 1 near the station during the operation period was carried out. The four major tunnel structural diseases including water leakage, segment stagger, open joints, and lining cracks were counted. The distribution law of the structural diseases along the longitudinal and circumferential directions of the interval tunnel was analyzed. The service status of segment components and connecting bolts were evaluated based on existing specification. The overall service status of the tunnel was determined. The service status level of the upstream line was determined as “iii”, and the service status was “degradation”, the service status level of the downstream line was determined as “iv” and the service status was “deteriorated”.
Different from an arch bridge, the load-carrying capacity of a box structure mainly depends on the bending capacity of corrugated steel. This paper explores the mechanical properties of a corrugated steel box bridge. The mechanical properties of a 13 m span corrugated steel box bridge under static and dynamic loads were tested. Three static load conditions were tested, and four dynamic load conditions were tested, including 20 km/h, 40 km/h, 60 km/h, and 80 km/h. Through the analysis of section strain, vault displacement, dynamic strain, and internal force, the following conclusions can be drawn: (1) when the static load changes from the right arch foot and vault to the left arch foot, the strain value of each measuring point continues to increase, which may be caused by the accumulation of deformation due to the adjustment of the stress state of the soil and corrugated steel caused by loading; (2) the displacement change in the test is more sensitive than the strain change; (3) the vault strain reaches the maximum value at a specific speed of 60 km/h. This is related to the structural resonance caused by vehicle operation, and the natural frequency of the corrugated steel box bridge can be determined by a field vehicle dynamic load test; (4) the damping value of an embedded corrugated steel bridge is large, and the energy dissipation capacity is strong, which is very beneficial to structural earthquake resistance and to reducing the structural resonance under traffic load; (5) the dynamic increasing strain coefficient is less than 1, which means that the strain caused by a dynamic load is far less than that caused by a static load, and it reaches the maximum value at a certain speed (60km/h); (6) the maximum bending stress and maximum axial stress of the corrugated steel box bridge tested in this paper are basically the same, which indicates that the axial stress of the box structure cannot be ignored. However, the box structure design method proposed in the CHBDC code does not consider the axial stress, so it is necessary to further improve the box structure design method; (7) most of the axial force of a box corrugated steel bridge is tensile force. The pavement structure layer has an effect on the overall performance of the corrugated steel box bridge, which is similar to the decompression plate: it makes the overall stress (I ∼ V section) more uniform and the bending moment smaller.
The physical and mechanical properties of calcareous concretion soil depend largely on the shape, size and distribution of calcareous concretion soil besides the impact of soil layer. Due to the long time required for clay saturation, consolidation, and shearing, as well as the tedious sample preparation, larger triaxial tests of calcareous nodules have not been carried out. In this chapter, based on the medium triaxial test of calcareous nodules, the strength characteristics of remolded soil samples under different confining pressures are studied. By controlling parameters such as calcareous nodules particle size and water content, the impact of different test conditions on the strength of calcareous nodules is analysed, and the variation rule is analysed. It is concluded that the impact of nodular particle size on soil strength is not obvious at 20% nodular content. The impact of different water content on the strength of soil is more regular, showing hardening characteristics, in line with the natural law.
As well known, foundation pit excavation influences the stress and deformation of adjacent soil, and thus existing tunnel. However, the behavior on the deformation of a twin-track tunnel subjected to adjacent excavation is not clear. In order to investigate this behavior, a series of numerical simulations using PLAXIS are conducted in this study. The result shows that the displacement and internal forces near the foundation pit is almost double those far away. Moreover, as the depth of excavation reaches the burial depth of tunnel, the value of displacement of tunnel begins to increase markedly.
In this article Lingnan Impression Park is taken as case study to research on integrated strategies of cultural heritage conservation with the purpose of its adapted reuse. In process exploitation, a combined strategy reusing architecture heritage is adopted, to produce an atmosphere of traditional Lingnan (Cantonese) culture for tourism development. This strategy has advantages for material recycle, construction energy saving and environmental protection, but arising an issue concerning heritage’s authenticity. It is regarded that it must be adopted a cultural ecology’s views to deal with the concept of authenticity especially in circumstance of heritage reuse with tourism exploitation.
With the rapid development of urbanization, urban planning will inevitably be accompanied by discussions on the transformation of old communities. How to integrate and develop the transformation of old communities with the renewal and protection of historical and cultural blocks is also the object of our research. Regarding the creation of the atmosphere of the public space in the old quarters in the historical and cultural blocks, it is the inheritance of the historical context in the urban planning. Taking the transformation of Wuhan Tanhualin community as an example, based on the theory of urban acupuncture and moxibustion, this article discusses the planning strategy of how to solve the public space transformation of old communities in historical and cultural districts at multiple levels and multiple dimensions. Conduct public space analysis and public life surveys on old communities through literature analysis and field research methods, put forward strategies for the transformation of old communities in emergent public health safety incidents, and advocate low-impact development construction methods to realize the old community areas Sustainable development. When dealing with the connection between the new and the old space, it can establish a visual dialogue relationship between the new and the old space, and at the same time establish the historical and humanistic resonance effect between the public space and the historical and cultural block. Create an old community public space with historical and cultural characteristics, green and safe coordination.