A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to me...A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to measure earth and water pressures simultaneously.The proposed transducer has advantages of small size,high sensitivity,low cost,immunity to electromagnetic interference and rapid prototyping.The working principle,design parameters,and manufacturing details are discussed.The proposed transducer was calibrated for earth and water pressures measurement by using weights and a specially designed pressure chamber,respectively.The calibration results showed that the wavelength of the transducer was proportional to the applied pressure.The sensitivity coefficients of the earth and water pressures were 12.633 nm/MPa and 6.282 nm/MPa,respectively.Repeated tests and error analysis demonstrated the excellent stability and accuracy of the earth and water pressure measurements.The performance of the proposed transducer was further verified by a model experimental test and numerical analysis,which indicated that the proposed transducer has great potential for practical applications.展开更多
Portal water injection sheet pile (PWISP), as a retaining wall, appeared in seashore engineering in 2000. Although there have been many systematic methods addressing the issue, there are very few focusing on the new s...Portal water injection sheet pile (PWISP), as a retaining wall, appeared in seashore engineering in 2000. Although there have been many systematic methods addressing the issue, there are very few focusing on the new structure because of the difficulties in defining the earth pressure between the two piles. A new method is proposed in this paper to obtain the earth pressure between the PWISPs. Stability analysis against overturning follows as a consequence. Using Finite Element Analysis (FEA) software ANSYS, both the nonlinear characteristics of the soil and those of the contact elements are taken into account to obtain the earth pressure distribution on the contact surface. Based on the results of the FEA, Rankin’s theory and the slip plane theory, the formula of the earth pressure on the inner surfaces between the piles is given. Assuming the PWISP as the analysis object and the earth pressure as an outside force acting upon it, the equation of stability against overturning of the PWISP is presented. Finally, some parameters are discussed about the stability of the PWISP against overturning, such as the embedded depth of the front pile, the distance between the two rows of piles, the internal friction angle and the cohesion of the earth. The results show that the increase of the cohesion and the internal friction angle will decrease the distance and the embedded depth, and therefore enhance the stability against overturning. Specifically, when the distance is 1/3-2/3 of the maximal excavation depth, the two rows of piles give the best performance in stability.展开更多
Rainfall is one of the most important factors contributing to landslides, and gentle bedding incline, high-rainfall induced landslides are common throughout the world. Field observations and theoretical analyses have ...Rainfall is one of the most important factors contributing to landslides, and gentle bedding incline, high-rainfall induced landslides are common throughout the world. Field observations and theoretical analyses have been used to assess slope instability caused by permeability variation. In this study, the influence of rainfall infiltration on gentle bedding incline slope behaviour was investigated using a centrifuge physical simulation test. The magnitude, pattern and development of pore water and earth pressure at the interface;the shear failure surface features;and the corresponding deformation and failure processes were considered. A model with interbedded sand and mud was created, and a centrifuge was used to simulate both natural and rainfall conditions. The weak intercalation was composed of single-material silty clay, and the landslide mass was composed of red-bed sandstone. A combination of photography, pore water pressure measurements and earth pressure measurements were used to examine the relationship between the pore water pressure, earth pressure and failure modes. When the slope experiences overall instability, the curves of the earth pressure and pore water pressure dramatically decrease. The results reveal that the failure shear surface largely depends on the differential creep caused by the properties of the rock mass and the rainfall infiltration.展开更多
Pulsating pressure plays an important role in improving the poor irrigation quality and the uneven water distribution caused by the terrain slope.Water distribution is one of the key factors in design of the sprinkler...Pulsating pressure plays an important role in improving the poor irrigation quality and the uneven water distribution caused by the terrain slope.Water distribution is one of the key factors in design of the sprinkler irrigation system,however,it is difficult to measure in practice.To provide appropriate technical parameters for the design of sprinkler irrigation system with pulsating pressure on sloping land,a mathematical model was established according to the water conservation principle and finite element idea,and its accuracy was experimentally verified.The model was applied to study the effects of terrain slope,sprinkler arrangement,sprinkler spacing and average pulsating pressure on water distribution on sloping land.The results showed that the water distribution was more favorable under the gentle terrain slope,when slope decreased from 25%to 5%,the uniformity increased from 74.47%to 86.22%.Sprinklers arranged in equilateral triangle and with the spacing close to R_(0)had the best water distribution uniformity,the uniformity coefficient(CU)of which was 11.43%and 8.75%higher than that in square and rectangular arrangement,respectively.The CU increased with the increase of the average pulsating pressure.However,the effect of increasing water pressure on promoting the uniformity of water distribution gradually decreases.Therefore,when using the Rainbird R5000 sprinkler on sloping land with pulsating pressure,it is suggested that the sprinkler irrigation systems should be arranged below the terrain slope of 20%,and operated at the average pulsating pressure of 300 kPa.The suitable sprinkler arrangement is the equilateral triangle,and with the spacing of 0.8R_(0)to 1.0R_(0).展开更多
基金funding support from the National Natural Science Foundation of China(Grant Nos.41972271 and 42177127)Sanya Science and Education Innovation Park of Wuhan University of Technology(Grant No.2020KF0007)。
文摘A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to measure earth and water pressures simultaneously.The proposed transducer has advantages of small size,high sensitivity,low cost,immunity to electromagnetic interference and rapid prototyping.The working principle,design parameters,and manufacturing details are discussed.The proposed transducer was calibrated for earth and water pressures measurement by using weights and a specially designed pressure chamber,respectively.The calibration results showed that the wavelength of the transducer was proportional to the applied pressure.The sensitivity coefficients of the earth and water pressures were 12.633 nm/MPa and 6.282 nm/MPa,respectively.Repeated tests and error analysis demonstrated the excellent stability and accuracy of the earth and water pressure measurements.The performance of the proposed transducer was further verified by a model experimental test and numerical analysis,which indicated that the proposed transducer has great potential for practical applications.
文摘Portal water injection sheet pile (PWISP), as a retaining wall, appeared in seashore engineering in 2000. Although there have been many systematic methods addressing the issue, there are very few focusing on the new structure because of the difficulties in defining the earth pressure between the two piles. A new method is proposed in this paper to obtain the earth pressure between the PWISPs. Stability analysis against overturning follows as a consequence. Using Finite Element Analysis (FEA) software ANSYS, both the nonlinear characteristics of the soil and those of the contact elements are taken into account to obtain the earth pressure distribution on the contact surface. Based on the results of the FEA, Rankin’s theory and the slip plane theory, the formula of the earth pressure on the inner surfaces between the piles is given. Assuming the PWISP as the analysis object and the earth pressure as an outside force acting upon it, the equation of stability against overturning of the PWISP is presented. Finally, some parameters are discussed about the stability of the PWISP against overturning, such as the embedded depth of the front pile, the distance between the two rows of piles, the internal friction angle and the cohesion of the earth. The results show that the increase of the cohesion and the internal friction angle will decrease the distance and the embedded depth, and therefore enhance the stability against overturning. Specifically, when the distance is 1/3-2/3 of the maximal excavation depth, the two rows of piles give the best performance in stability.
文摘Rainfall is one of the most important factors contributing to landslides, and gentle bedding incline, high-rainfall induced landslides are common throughout the world. Field observations and theoretical analyses have been used to assess slope instability caused by permeability variation. In this study, the influence of rainfall infiltration on gentle bedding incline slope behaviour was investigated using a centrifuge physical simulation test. The magnitude, pattern and development of pore water and earth pressure at the interface;the shear failure surface features;and the corresponding deformation and failure processes were considered. A model with interbedded sand and mud was created, and a centrifuge was used to simulate both natural and rainfall conditions. The weak intercalation was composed of single-material silty clay, and the landslide mass was composed of red-bed sandstone. A combination of photography, pore water pressure measurements and earth pressure measurements were used to examine the relationship between the pore water pressure, earth pressure and failure modes. When the slope experiences overall instability, the curves of the earth pressure and pore water pressure dramatically decrease. The results reveal that the failure shear surface largely depends on the differential creep caused by the properties of the rock mass and the rainfall infiltration.
基金This research was funded by National Natural Science Foundation of China(51779246).
文摘Pulsating pressure plays an important role in improving the poor irrigation quality and the uneven water distribution caused by the terrain slope.Water distribution is one of the key factors in design of the sprinkler irrigation system,however,it is difficult to measure in practice.To provide appropriate technical parameters for the design of sprinkler irrigation system with pulsating pressure on sloping land,a mathematical model was established according to the water conservation principle and finite element idea,and its accuracy was experimentally verified.The model was applied to study the effects of terrain slope,sprinkler arrangement,sprinkler spacing and average pulsating pressure on water distribution on sloping land.The results showed that the water distribution was more favorable under the gentle terrain slope,when slope decreased from 25%to 5%,the uniformity increased from 74.47%to 86.22%.Sprinklers arranged in equilateral triangle and with the spacing close to R_(0)had the best water distribution uniformity,the uniformity coefficient(CU)of which was 11.43%and 8.75%higher than that in square and rectangular arrangement,respectively.The CU increased with the increase of the average pulsating pressure.However,the effect of increasing water pressure on promoting the uniformity of water distribution gradually decreases.Therefore,when using the Rainbird R5000 sprinkler on sloping land with pulsating pressure,it is suggested that the sprinkler irrigation systems should be arranged below the terrain slope of 20%,and operated at the average pulsating pressure of 300 kPa.The suitable sprinkler arrangement is the equilateral triangle,and with the spacing of 0.8R_(0)to 1.0R_(0).
