Traditional construction techniques have a significant impact on the environment and are associated with long construction durations in the construction of municipal rainwater pipelines.Pipe jacking technology,a new t...Traditional construction techniques have a significant impact on the environment and are associated with long construction durations in the construction of municipal rainwater pipelines.Pipe jacking technology,a new type of pipeline construction method,enables non-excavation construction and can address the shortcomings of traditional pipeline construction.This article analyzes the concept and application advantages of pipe jacking technology.Combining engineering examples,it explores the application strategies of pipe jacking technology in the construction process of municipal rainwater pipelines for reference.展开更多
[Object] The research aimed to find out seed germination conditions and regulations.[Method] Seeds were soaked by clear water and 4 chemical agents of different concentrations(NaHCO3,KHCO3,K2CO3,NaClO)then conducted g...[Object] The research aimed to find out seed germination conditions and regulations.[Method] Seeds were soaked by clear water and 4 chemical agents of different concentrations(NaHCO3,KHCO3,K2CO3,NaClO)then conducted germination test in illumination box.[Result] Seed germination number and absolute germination rate(above 80%)in water treatment group was obviously higher than other treatments.[Conclusion] No dormancy phenomenon in mature embryo and no inhibition in seed coat,so conventional moist treatment can induct seed germination.展开更多
To shorten the existing box culvert demolition construction period and ensure the normal operation of the railway, the jacking-out construction method was adopted. The ABAQUS finite element software was used to establ...To shorten the existing box culvert demolition construction period and ensure the normal operation of the railway, the jacking-out construction method was adopted. The ABAQUS finite element software was used to establish a three-dimensional model of the box culvert and soil body of the relying project, and three excavation thickness (0m, 1 m, 2 m) were used as the main variation parameters for numerical analysis and research, and the change law of the box culvert itself and soil body stress during the culvert jacking out process was obtained. The results show that the jacking force-displacement curves of the three working conditions can be divided into two stages, and the jacking force reaches the maximum value at the moment when the static friction turns into sliding friction at the end of the first stage. The stress distribution at the bottom slab of the box culvert in the jacking process is approximately normal, and the stress decreases with the increase of the roadbed excavation thickness. The increase of the roadbed excavation thickness can reduce the soil pressure on the side of the box culvert and effectively reduce the deformation of the roadbed in the jacking-out process. The deformation of the roadbed during the jacking process can be reduced by increasing the thickness of the roadbed excavation.展开更多
文摘Traditional construction techniques have a significant impact on the environment and are associated with long construction durations in the construction of municipal rainwater pipelines.Pipe jacking technology,a new type of pipeline construction method,enables non-excavation construction and can address the shortcomings of traditional pipeline construction.This article analyzes the concept and application advantages of pipe jacking technology.Combining engineering examples,it explores the application strategies of pipe jacking technology in the construction process of municipal rainwater pipelines for reference.
基金Supported by Demonstration Project of Cropping Structure Adjustment Comprehensive Technique"Research and Demonstration on Molecular Marker and High-yield Adjustment Technology of Uncaria,the Genuine Me-dicinal Material in Guizhou"(Project of Agriculture and Planting in Guizhou Agricultural Department[2005]08)~~
文摘[Object] The research aimed to find out seed germination conditions and regulations.[Method] Seeds were soaked by clear water and 4 chemical agents of different concentrations(NaHCO3,KHCO3,K2CO3,NaClO)then conducted germination test in illumination box.[Result] Seed germination number and absolute germination rate(above 80%)in water treatment group was obviously higher than other treatments.[Conclusion] No dormancy phenomenon in mature embryo and no inhibition in seed coat,so conventional moist treatment can induct seed germination.
文摘To shorten the existing box culvert demolition construction period and ensure the normal operation of the railway, the jacking-out construction method was adopted. The ABAQUS finite element software was used to establish a three-dimensional model of the box culvert and soil body of the relying project, and three excavation thickness (0m, 1 m, 2 m) were used as the main variation parameters for numerical analysis and research, and the change law of the box culvert itself and soil body stress during the culvert jacking out process was obtained. The results show that the jacking force-displacement curves of the three working conditions can be divided into two stages, and the jacking force reaches the maximum value at the moment when the static friction turns into sliding friction at the end of the first stage. The stress distribution at the bottom slab of the box culvert in the jacking process is approximately normal, and the stress decreases with the increase of the roadbed excavation thickness. The increase of the roadbed excavation thickness can reduce the soil pressure on the side of the box culvert and effectively reduce the deformation of the roadbed in the jacking-out process. The deformation of the roadbed during the jacking process can be reduced by increasing the thickness of the roadbed excavation.
