The coastal region of Fujian contains numerous existing stone masonry structures,many of which are constructed on soft soil sites.Previous studies have shown that the soil-structure interaction(SSI)effect on soft soil...The coastal region of Fujian contains numerous existing stone masonry structures,many of which are constructed on soft soil sites.Previous studies have shown that the soil-structure interaction(SSI)effect on soft soil foundations can prolong the structure's natural vibration period and enhance its seismic response.We develops a soilstructure interaction system model and a comparative rigid foundation model using the finite element software LS-DYNA to investigate the impact of SSI on the dynamic characteristics and seismic response of stone structures.The results indicate that the SSI effect alters stone structures'dynamic properties and seismic response.This alteration is evident in the extended natural vibration period,which reduces overall stiffness,increases interstory displacement angles,and slightly decreases the acceleration response.Under both SSI and FIX systems,the structural failure mode is characterized by the external collapse of the second-story stone walls,which causes the roof stone slabs to lose support and fall,leading to overall collapse.The FIX system demonstrates better structural integrity and stability with slower crack development.In contrast,the SSI system exhibits cracks that appear earlier and develop more rapidly,causing more severe damage.The research findings provide a theoretical basis for the seismic reinforcement of existing stone structures on soft soil foundations.展开更多
The reinforcement effects of geosynthetics in thick soft subsoil case and thin soft subsoil case are studied in this paper,and a Duncan Chang nonlinear numerical model based on the finite element method (FEM) is deve...The reinforcement effects of geosynthetics in thick soft subsoil case and thin soft subsoil case are studied in this paper,and a Duncan Chang nonlinear numerical model based on the finite element method (FEM) is developed.Moreover,an important conclusion that the thickness of soft subsoil affects greatly the geotechnical behavior of geosynthetic reinforced embankments is drawn.A series of embankment built on soft subsoil is calculated using the FEM program.The results of the computer program,such as the lateral displacements,settlements,and stress level and shear stresses in the subsoil,are presented in great detail and the comparison of those results disposes clearly the huge discrepancy of reinforce benefit between the thick subsoil embankment and thin subsoil embankment.Reinforcement mechanism of geosynthetics is also discussed in this paper and several conclusions are reached.This paper also gives recommendations for design.展开更多
The motion of pore water directly influences mechanical properties of soils, which are variable during creep. Accurate description of the evolution of mechanical properties of soils can help to reveal the internal beh...The motion of pore water directly influences mechanical properties of soils, which are variable during creep. Accurate description of the evolution of mechanical properties of soils can help to reveal the internal behavior of pore water. Based on the idea of using the fractional order to reflect mechanical properties of soils, a fractional creep model is proposed by introducing a variable-order fractional operator, and realized on a series of creep responses in soft soils. A comparative analysis illustrates that the evolution of mechanical properties, shown through the simulated results, exactly corresponds to the motion of pore water and the solid skeleton. This demonstrates that the proposed variable-order fractional model can be employed to characterize the evolution of mechanical properties of and the pore water motion in soft soils during creep. It is observed that the fractional order from the proposed model is related to the dissipation rate of pore water pressure.展开更多
In view of the characteristics of soft soil deep foundation pit for the construction and geotechnical characteristics of the special medium,it is difficult to calculate theoreti- cally accurately structural deformatio...In view of the characteristics of soft soil deep foundation pit for the construction and geotechnical characteristics of the special medium,it is difficult to calculate theoreti- cally accurately structural deformation of the foundation pit,so in the course of excavation on the construction of the information is particularly important.The analysis and compari- son of several popular non-linear forecasting methods,combined with the actual projects, set up a grey theoretical prediction model,time series forecasting model,improved neural network model to predict deformation of the foundation pit.The results show that the use of neural network to predict with high accuracy solution,it is the foundation deformation prediction effective way in underground works with good prospects.展开更多
Construction issues of high-speed rail infrastructures have been increasingly concerned worldwide,of which the subgrade settlement in soft soil area becomes a particularly critical problem.Due to the high compressibil...Construction issues of high-speed rail infrastructures have been increasingly concerned worldwide,of which the subgrade settlement in soft soil area becomes a particularly critical problem.Due to the high compressibility and low permeability of soft soil,the post-construction settlement of the subgrade is extremely difficult to control in these regions,which seriously threatens the operation safety of high-speed trains.In this work,the significant issues of high-speed railway subgrades in soft soil regions are discussed.The theoretical and experimental studies on foundation treatment methods for ballasted and ballastless tracks are reviewed.The settlement evolution and the settlement control effect of different treatment methods are highlighted.Control technologies of subgrade differential settlement are subsequently briefly presented.Settlement calculation algorithms of foundations reinforced by different treatment methods are discussed in detail.The defects of existing prediction methods and the challenges faced in their practical applications are analyzed.Furthermore,the guidance on future improvement in control theories and technologies of subgrade settlement for high-speed railway lines and the corresponding challenges are provided.展开更多
Abundant practical evidences have indicated that the soil progressively loses its structural configuration under construction disturbance and this can result in long-term macro deformation.The fundamental understandin...Abundant practical evidences have indicated that the soil progressively loses its structural configuration under construction disturbance and this can result in long-term macro deformation.The fundamental understanding of soil microstructure evolution subject to construction disturbance is necessary for controlling disturbance in excavation projects and minimizing ground settlement.The microstructure of Shanghai soft soil is investigated in this study.The laboratory isotropic compression tests are respectively performed on the virgin soil and the reconstructed Shanghai soft soil to investigate the macro deformation of soil under disturbance.Discrete element method model is used to study the micro particle level responses of soil under disturbance.The laboratory tests and numerical simulations provide theoretical basis for construction disturbance mitigation to ensure safety and stability of excavation projects.展开更多
Finite element method was performed to investigate the influences of beam stiffness, foundation width and cushion thickness on the beating capacity of beam foundation on underlying weak laminated clay. The comparison ...Finite element method was performed to investigate the influences of beam stiffness, foundation width and cushion thickness on the beating capacity of beam foundation on underlying weak laminated clay. The comparison between numerical results and results from field test including plate-bearing test and foundation settlement observation shows reasonable agreement. According to the numerical results, the beam width, length, cross section and cushion thickness were optimized. The results show that the stresses in subgrade soil decrease greatly with increasing the cushion thickness and width of foundation. However, the foundation settlement and influencing depth of displacement also increase correspondingly under conditions of relatively thinner cushion thickness. For the foundations on underlying weak layer, increasing foundation width merely might be inadequate for improving the bearing capacity, and the appropriate width and cushion thickness depend on the response of subgrade. A comparison between rigid and flexible beams was also discussed. The influence of a flexible beam foundation on subgrade is relatively smaller under the same loading conditions, and the flexible beam foundation appears more adaptable to various subgrades. The proposed flexible beam foundation was adopted in engineering. According to the calculation results, beam width of 2.4 m and cushion thickness of 0.8 m are proposed, and a flexible beam foundation is applied in the optimized design, which is confirmed reasonable by the actual engineering.展开更多
The flow characteristics of foundation soils subjected to train loads can present engineering hazards in highspeed railways.In order to verify the feasibility of blending coarse sand in modifying soft subsoil,undraine...The flow characteristics of foundation soils subjected to train loads can present engineering hazards in highspeed railways.In order to verify the feasibility of blending coarse sand in modifying soft subsoil,undrained pulling sphere tests were carried out and the train loads were simulated through localized and cyclic vibration at various frequencies.Laboratory testing results indicate that the fl ow characteristics of soft soil can be signifi cantly enhanced by high-frequency vibration;meanwhile the continuous increase in fl ow characteristics caused by cyclic vibration may be an important reason for the long-term settlement of soft subsoil.The infl uence of sand content on fl ow characteristics is also studied in detail,and it is shown that the addition of coarse sand can weaken the fl ow characteristics of soft soil induced by sudden vibration at lower than 50 Hz.Under the condition of cyclic vibration,the growth of the fl ow characteristics of sand-clay mixtures is mainly caused by the fi rst-time vibration in the cycle,and the increase in sand content can make the fl ow characteristics present a faster convergent tendency.展开更多
This article examines the soft soil roadbed reinforcement technology for widened sections of highways in a specific project.It provides an overview of the project,the principles of soft soil roadbed reinforcement tech...This article examines the soft soil roadbed reinforcement technology for widened sections of highways in a specific project.It provides an overview of the project,the principles of soft soil roadbed reinforcement technology for wide sections,and its practical application.The analysis aims to offer guidance on applying soft soil roadbed wide section reinforcement technology and enhancing the overall quality of similar projects.展开更多
The stiffness has a large influence on the behavior of soils. Its value is affected by some of the soils properties, such as the over consolidated ratio(OCR), the effective normal stress, and the plasticity index etc....The stiffness has a large influence on the behavior of soils. Its value is affected by some of the soils properties, such as the over consolidated ratio(OCR), the effective normal stress, and the plasticity index etc. In this paper, the numerical modeling of soft soils was carried out using an improved elasto-plastic S-clay1 model accounting for degradation of stiffness. The relation between the stiffness and the shear strain was established based on a large number of experimental data. The effects of strain-dependent stiffness of normally consolidated soils and over consolidated soils on the stress-strain behavior were studied through a comparison of the simulations with the experimental results of undrained triaxial compression tests. The results show that the behaviors of soils can be well predicted with the improved constitutive model, particularly before the peak stress.展开更多
Shanghai is located in eastern China and is built on overburden soil layers. It can be seen from the Mexico M S=8.1 earthquake on September 19, 1985 and the Hanshin M S=7.4 earthquake on January 17,1995 that heavy cas...Shanghai is located in eastern China and is built on overburden soil layers. It can be seen from the Mexico M S=8.1 earthquake on September 19, 1985 and the Hanshin M S=7.4 earthquake on January 17,1995 that heavy casualties and property losses have a direct relationship with overburden soil layers. Ground motions caused by earthquakes are significantly amplified when passing through the soil layers. Under the influence of these amplified motions, building structures, whose nature frequency is within the frequency band of soil amplification response, will experience more severe damage than those built on bedrock. Therefore, engineering seismologists have paid considerable attention the amplification responses in the Shanghai overburden soil layers. The amplification responses of soil and sand layers in this paper are given by the M L=4.1 earthquake in Nantong, Jiangsu Province on December 25, 2001 at 31.8° N, 120.9° E. It can be seen that the responses of soil and sand layers are very different. That is important.展开更多
The silt soft soil in Nansha District of Guangzhou was the softest soft soil in China. It had the characteristics of high natural water content, high compressibility, long consolidation time, and complex layered distr...The silt soft soil in Nansha District of Guangzhou was the softest soft soil in China. It had the characteristics of high natural water content, high compressibility, long consolidation time, and complex layered distribution of soil layers. These characteristics formed the clogging characteristics of silt soft soil, which greatly increased the construction difficulty and hindered the construction progress. Therefore, based on the basic physical and mechanical properties of silt soft soil in Nansha District of Guangzhou, this paper evaluated the clogging characteristics of three silt soft soil areas in Nansha District of Guangzhou through long-term permeability test, and carried out scanning electron microscope test to explore the influence of different parameters and microstructure on the clogging difficulty of silt soft soil. The results showed that the silt soft soil Zone I and Zone II (shallow layer) in Nansha District of Guangzhou were divided into slight siltation levels, and the silt soft soil Zone III (deep layer) was mild siltation level. Large pores were widely distributed in shallow silt soft soil, while the continuity of large pores in deep silt soft soil was poor. The migration of fine particles that failed to establish contact with surrounding particles in the soil blocks the small pores of seepage and thus produces siltation.展开更多
Formation deformation is inevitable in subway tunnel construction, and serious consequences will be caused if it is not controlled in time. Especially for shield tunnel under the condition of soft soil stratum, the st...Formation deformation is inevitable in subway tunnel construction, and serious consequences will be caused if it is not controlled in time. Especially for shield tunnel under the condition of soft soil stratum, the stratum deformation will be more complicated due to its high water content, large pore ratio, high compressibility, low strength, high sensitivity, easy thixotropy, rheology and other undesirable characteristics. Therefore, how to effectively guarantee the safety of tunnel construction in soft soil stratum has become the focus and difficulty of engineering control. Taking the large shield tunnel construction as an example, this paper analyzes the data of shield construction in soft soil stratum, and puts forward the shield tunneling construction technology and matters needing attention in similar stratum, so as to provide reference for shield construction in soft soil stratum in the future.展开更多
Scientific treatment of soft soil foundation can make the foundation structure more stable, effectively control all links in highway soft soil foundation construction, ensure the smooth progress of subsequent highway ...Scientific treatment of soft soil foundation can make the foundation structure more stable, effectively control all links in highway soft soil foundation construction, ensure the smooth progress of subsequent highway engineering construction and ensure the construction quality of highway engineering. Therefore, it is very important to strengthen the construction management of highway construction soft soil foundation. In the process of expressway construction, the highway construction unit also needs to pay more attention to the soft soil foundation, and take targeted soft soil foundation treatment technology on the basis of combining the local geological and climatic characteristics, so as to lay a good foundation for the subsequent expressway construction. By taking targeted treatment measures, the construction results of highway soft soil subgrade are maintained, which provides a reliable guarantee for the overall construction of highway.展开更多
For highway engineering construction, foundation is very important, especially the project is located in soft soil foundation. Corresponding measures must be taken according to the specific situation to ensure the sta...For highway engineering construction, foundation is very important, especially the project is located in soft soil foundation. Corresponding measures must be taken according to the specific situation to ensure the stability of subgrade. However, in the construction of modern highway engineering, the soft soil foundation is generally unstable, which affects the quality of highway materials. It can be seen that in order to promote highway engineering orderly and ensure its quality and safety, highway engineering construction units must change the existing construction mode, so as to promote the vigorous development of highway engineering.展开更多
Subgrade construction is a very important part of the overall highway construction. Then as far as the soft soil subgrade is concerned, the overall construction is correspondingly difficult. During the construction pe...Subgrade construction is a very important part of the overall highway construction. Then as far as the soft soil subgrade is concerned, the overall construction is correspondingly difficult. During the construction period, it is necessary to strengthen the application of corresponding new materials and construction technologies, and at the same time, carry out the construction accurately and correctly according to the overall construction process, so as to ensure that the construction will not fail to meet the standards due to the influence of relevant factors after the completion of the construction, which in turn will cause obstacles to the development of the highway engineering industry.展开更多
With the acceleration of urbanization, the soft foundation treatment technology of urban roads has also been developed by leaps and bounds. However, in the construction of municipal projects, the construction scheme s...With the acceleration of urbanization, the soft foundation treatment technology of urban roads has also been developed by leaps and bounds. However, in the construction of municipal projects, the construction scheme should be selected according to the actual situation to ensure the project quality and maximize the social benefits of municipal roads. We should make bold innovations in combination with reality, constantly improve and optimize the treatment methods of soft soil subgrade, continuously improve the scientific analysis ability of soft soil subgrade, enhance the safety and durability of urban roads, and meet the requirements of urban road construction.展开更多
With the rapid development of China's social economy, China has also made great progress in infrastructure construction, especially in highway construction in China, which has made great contribution to the develo...With the rapid development of China's social economy, China has also made great progress in infrastructure construction, especially in highway construction in China, which has made great contribution to the development of China's transportation and the improvement of economic development. Road and bridge construction activities are an important part of construction projects. In order to ensure the smooth progress of urban infrastructure construction activities, highway and bridge construction personnel are required to seriously carry out various quality control activities to promote the significant improvement of soft soil foundation construction technology. In the process of highway construction, various types of foundations are involved, among which the construction of soft soil foundation is a typical one. Therefore, in the process of practice, we should fully grasp the corresponding soft soil foundation construction technology and implement various technical points, so as to more effectively strengthen the construction quality of the overall project and provide the necessary conditions for its safe and stable operation. Based on this situation, this paper focuses on the analysis of the main characteristics of soft soil foundation and the application strategies of soft soil foundation construction technology in the process of highway construction. Modern means of transportation put forward higher requirements for the quality of road infrastructure. This paper discusses the details of soft soil foundation construction control technology in highway bridge construction and puts forward some feasible suggestions for improving the construction technology of soft soil foundation. It is hoped that the analysis in this paper can provide some enlightenment for the improvement of highway bridge construction quality.展开更多
It is very important to ensure the quality of highway bridge construction and do a good job in soft soil foundation treatment. Only by effectively controlling the overall quality of soft soil foundation treatment can ...It is very important to ensure the quality of highway bridge construction and do a good job in soft soil foundation treatment. Only by effectively controlling the overall quality of soft soil foundation treatment can the stability and reliability of highway bridge structure be effectively controlled and the smooth development of highway bridge construction activities be promoted as a whole. In highway and bridge construction activities, the treatment of soft soil foundation is the key. Only by doing a good job in the treatment of soft soil foundation can the service life of the project be effectively prolonged. If the soft soil foundation is not treated, it will cause problems such as road bridge subgrade subsidence and cracks. Only by ensuring the overall quality of subgrade treatment can a solid foundation be laid for the quality control of actual road bridge construction activities.展开更多
With the development of Chinas economy, the state has gradually increased the strength of municipal highway engineering construction. The geological environment conditions in different areas are very different. In the...With the development of Chinas economy, the state has gradually increased the strength of municipal highway engineering construction. The geological environment conditions in different areas are very different. In the process of municipal engineering construction, the construction quality of soft soil subgrade is affected by many factors, such as construction environment, construction requirements and so on, and there are some construction problems such as subgrade settlement. It is necessary to select the construction technology, combine the actual situation of the site, consider various factors, and fully understand the applicable conditions and advantages of various treatment technologies, so as to ensure the actual effect of soft soil foundation treatment and the orderly development of road engineering construction.展开更多
基金jointly sponsored by Fujian Province construction science and technology development research project(2023-B-07,2023-K-47,2022-K-118)。
文摘The coastal region of Fujian contains numerous existing stone masonry structures,many of which are constructed on soft soil sites.Previous studies have shown that the soil-structure interaction(SSI)effect on soft soil foundations can prolong the structure's natural vibration period and enhance its seismic response.We develops a soilstructure interaction system model and a comparative rigid foundation model using the finite element software LS-DYNA to investigate the impact of SSI on the dynamic characteristics and seismic response of stone structures.The results indicate that the SSI effect alters stone structures'dynamic properties and seismic response.This alteration is evident in the extended natural vibration period,which reduces overall stiffness,increases interstory displacement angles,and slightly decreases the acceleration response.Under both SSI and FIX systems,the structural failure mode is characterized by the external collapse of the second-story stone walls,which causes the roof stone slabs to lose support and fall,leading to overall collapse.The FIX system demonstrates better structural integrity and stability with slower crack development.In contrast,the SSI system exhibits cracks that appear earlier and develop more rapidly,causing more severe damage.The research findings provide a theoretical basis for the seismic reinforcement of existing stone structures on soft soil foundations.
文摘The reinforcement effects of geosynthetics in thick soft subsoil case and thin soft subsoil case are studied in this paper,and a Duncan Chang nonlinear numerical model based on the finite element method (FEM) is developed.Moreover,an important conclusion that the thickness of soft subsoil affects greatly the geotechnical behavior of geosynthetic reinforced embankments is drawn.A series of embankment built on soft subsoil is calculated using the FEM program.The results of the computer program,such as the lateral displacements,settlements,and stress level and shear stresses in the subsoil,are presented in great detail and the comparison of those results disposes clearly the huge discrepancy of reinforce benefit between the thick subsoil embankment and thin subsoil embankment.Reinforcement mechanism of geosynthetics is also discussed in this paper and several conclusions are reached.This paper also gives recommendations for design.
基金supported by the Natural Science Foundation of Jiangsu Province of China(Grant No.BK2012810)the Fundamental Research Funds for the Central Universities(Grant No.2009B15114)
文摘The motion of pore water directly influences mechanical properties of soils, which are variable during creep. Accurate description of the evolution of mechanical properties of soils can help to reveal the internal behavior of pore water. Based on the idea of using the fractional order to reflect mechanical properties of soils, a fractional creep model is proposed by introducing a variable-order fractional operator, and realized on a series of creep responses in soft soils. A comparative analysis illustrates that the evolution of mechanical properties, shown through the simulated results, exactly corresponds to the motion of pore water and the solid skeleton. This demonstrates that the proposed variable-order fractional model can be employed to characterize the evolution of mechanical properties of and the pore water motion in soft soils during creep. It is observed that the fractional order from the proposed model is related to the dissipation rate of pore water pressure.
基金the Educational Department of Liaoning Province Through Scientific Research Project(20060051)National Natural Science Foundation of China(50604009)Universities Excellent Talents Support Plan to Train Foundation of Liaoning(RC-04-13)
文摘In view of the characteristics of soft soil deep foundation pit for the construction and geotechnical characteristics of the special medium,it is difficult to calculate theoreti- cally accurately structural deformation of the foundation pit,so in the course of excavation on the construction of the information is particularly important.The analysis and compari- son of several popular non-linear forecasting methods,combined with the actual projects, set up a grey theoretical prediction model,time series forecasting model,improved neural network model to predict deformation of the foundation pit.The results show that the use of neural network to predict with high accuracy solution,it is the foundation deformation prediction effective way in underground works with good prospects.
基金National Natural Science Foundation of China(No.51778485).
文摘Construction issues of high-speed rail infrastructures have been increasingly concerned worldwide,of which the subgrade settlement in soft soil area becomes a particularly critical problem.Due to the high compressibility and low permeability of soft soil,the post-construction settlement of the subgrade is extremely difficult to control in these regions,which seriously threatens the operation safety of high-speed trains.In this work,the significant issues of high-speed railway subgrades in soft soil regions are discussed.The theoretical and experimental studies on foundation treatment methods for ballasted and ballastless tracks are reviewed.The settlement evolution and the settlement control effect of different treatment methods are highlighted.Control technologies of subgrade differential settlement are subsequently briefly presented.Settlement calculation algorithms of foundations reinforced by different treatment methods are discussed in detail.The defects of existing prediction methods and the challenges faced in their practical applications are analyzed.Furthermore,the guidance on future improvement in control theories and technologies of subgrade settlement for high-speed railway lines and the corresponding challenges are provided.
文摘Abundant practical evidences have indicated that the soil progressively loses its structural configuration under construction disturbance and this can result in long-term macro deformation.The fundamental understanding of soil microstructure evolution subject to construction disturbance is necessary for controlling disturbance in excavation projects and minimizing ground settlement.The microstructure of Shanghai soft soil is investigated in this study.The laboratory isotropic compression tests are respectively performed on the virgin soil and the reconstructed Shanghai soft soil to investigate the macro deformation of soil under disturbance.Discrete element method model is used to study the micro particle level responses of soil under disturbance.The laboratory tests and numerical simulations provide theoretical basis for construction disturbance mitigation to ensure safety and stability of excavation projects.
基金Projects(50778181, 51178472) supported by the National Natural Science Foundation of China Project(2007045) supported by the Transportation Department of Hunan Province,China
文摘Finite element method was performed to investigate the influences of beam stiffness, foundation width and cushion thickness on the beating capacity of beam foundation on underlying weak laminated clay. The comparison between numerical results and results from field test including plate-bearing test and foundation settlement observation shows reasonable agreement. According to the numerical results, the beam width, length, cross section and cushion thickness were optimized. The results show that the stresses in subgrade soil decrease greatly with increasing the cushion thickness and width of foundation. However, the foundation settlement and influencing depth of displacement also increase correspondingly under conditions of relatively thinner cushion thickness. For the foundations on underlying weak layer, increasing foundation width merely might be inadequate for improving the bearing capacity, and the appropriate width and cushion thickness depend on the response of subgrade. A comparison between rigid and flexible beams was also discussed. The influence of a flexible beam foundation on subgrade is relatively smaller under the same loading conditions, and the flexible beam foundation appears more adaptable to various subgrades. The proposed flexible beam foundation was adopted in engineering. According to the calculation results, beam width of 2.4 m and cushion thickness of 0.8 m are proposed, and a flexible beam foundation is applied in the optimized design, which is confirmed reasonable by the actual engineering.
基金Natural Science Foundation of Jiangsu Province of China under Grant No.BK2012810
文摘The flow characteristics of foundation soils subjected to train loads can present engineering hazards in highspeed railways.In order to verify the feasibility of blending coarse sand in modifying soft subsoil,undrained pulling sphere tests were carried out and the train loads were simulated through localized and cyclic vibration at various frequencies.Laboratory testing results indicate that the fl ow characteristics of soft soil can be signifi cantly enhanced by high-frequency vibration;meanwhile the continuous increase in fl ow characteristics caused by cyclic vibration may be an important reason for the long-term settlement of soft subsoil.The infl uence of sand content on fl ow characteristics is also studied in detail,and it is shown that the addition of coarse sand can weaken the fl ow characteristics of soft soil induced by sudden vibration at lower than 50 Hz.Under the condition of cyclic vibration,the growth of the fl ow characteristics of sand-clay mixtures is mainly caused by the fi rst-time vibration in the cycle,and the increase in sand content can make the fl ow characteristics present a faster convergent tendency.
文摘This article examines the soft soil roadbed reinforcement technology for widened sections of highways in a specific project.It provides an overview of the project,the principles of soft soil roadbed reinforcement technology for wide sections,and its practical application.The analysis aims to offer guidance on applying soft soil roadbed wide section reinforcement technology and enhancing the overall quality of similar projects.
文摘The stiffness has a large influence on the behavior of soils. Its value is affected by some of the soils properties, such as the over consolidated ratio(OCR), the effective normal stress, and the plasticity index etc. In this paper, the numerical modeling of soft soils was carried out using an improved elasto-plastic S-clay1 model accounting for degradation of stiffness. The relation between the stiffness and the shear strain was established based on a large number of experimental data. The effects of strain-dependent stiffness of normally consolidated soils and over consolidated soils on the stress-strain behavior were studied through a comparison of the simulations with the experimental results of undrained triaxial compression tests. The results show that the behaviors of soils can be well predicted with the improved constitutive model, particularly before the peak stress.
文摘Shanghai is located in eastern China and is built on overburden soil layers. It can be seen from the Mexico M S=8.1 earthquake on September 19, 1985 and the Hanshin M S=7.4 earthquake on January 17,1995 that heavy casualties and property losses have a direct relationship with overburden soil layers. Ground motions caused by earthquakes are significantly amplified when passing through the soil layers. Under the influence of these amplified motions, building structures, whose nature frequency is within the frequency band of soil amplification response, will experience more severe damage than those built on bedrock. Therefore, engineering seismologists have paid considerable attention the amplification responses in the Shanghai overburden soil layers. The amplification responses of soil and sand layers in this paper are given by the M L=4.1 earthquake in Nantong, Jiangsu Province on December 25, 2001 at 31.8° N, 120.9° E. It can be seen that the responses of soil and sand layers are very different. That is important.
文摘The silt soft soil in Nansha District of Guangzhou was the softest soft soil in China. It had the characteristics of high natural water content, high compressibility, long consolidation time, and complex layered distribution of soil layers. These characteristics formed the clogging characteristics of silt soft soil, which greatly increased the construction difficulty and hindered the construction progress. Therefore, based on the basic physical and mechanical properties of silt soft soil in Nansha District of Guangzhou, this paper evaluated the clogging characteristics of three silt soft soil areas in Nansha District of Guangzhou through long-term permeability test, and carried out scanning electron microscope test to explore the influence of different parameters and microstructure on the clogging difficulty of silt soft soil. The results showed that the silt soft soil Zone I and Zone II (shallow layer) in Nansha District of Guangzhou were divided into slight siltation levels, and the silt soft soil Zone III (deep layer) was mild siltation level. Large pores were widely distributed in shallow silt soft soil, while the continuity of large pores in deep silt soft soil was poor. The migration of fine particles that failed to establish contact with surrounding particles in the soil blocks the small pores of seepage and thus produces siltation.
文摘Formation deformation is inevitable in subway tunnel construction, and serious consequences will be caused if it is not controlled in time. Especially for shield tunnel under the condition of soft soil stratum, the stratum deformation will be more complicated due to its high water content, large pore ratio, high compressibility, low strength, high sensitivity, easy thixotropy, rheology and other undesirable characteristics. Therefore, how to effectively guarantee the safety of tunnel construction in soft soil stratum has become the focus and difficulty of engineering control. Taking the large shield tunnel construction as an example, this paper analyzes the data of shield construction in soft soil stratum, and puts forward the shield tunneling construction technology and matters needing attention in similar stratum, so as to provide reference for shield construction in soft soil stratum in the future.
文摘Scientific treatment of soft soil foundation can make the foundation structure more stable, effectively control all links in highway soft soil foundation construction, ensure the smooth progress of subsequent highway engineering construction and ensure the construction quality of highway engineering. Therefore, it is very important to strengthen the construction management of highway construction soft soil foundation. In the process of expressway construction, the highway construction unit also needs to pay more attention to the soft soil foundation, and take targeted soft soil foundation treatment technology on the basis of combining the local geological and climatic characteristics, so as to lay a good foundation for the subsequent expressway construction. By taking targeted treatment measures, the construction results of highway soft soil subgrade are maintained, which provides a reliable guarantee for the overall construction of highway.
文摘For highway engineering construction, foundation is very important, especially the project is located in soft soil foundation. Corresponding measures must be taken according to the specific situation to ensure the stability of subgrade. However, in the construction of modern highway engineering, the soft soil foundation is generally unstable, which affects the quality of highway materials. It can be seen that in order to promote highway engineering orderly and ensure its quality and safety, highway engineering construction units must change the existing construction mode, so as to promote the vigorous development of highway engineering.
文摘Subgrade construction is a very important part of the overall highway construction. Then as far as the soft soil subgrade is concerned, the overall construction is correspondingly difficult. During the construction period, it is necessary to strengthen the application of corresponding new materials and construction technologies, and at the same time, carry out the construction accurately and correctly according to the overall construction process, so as to ensure that the construction will not fail to meet the standards due to the influence of relevant factors after the completion of the construction, which in turn will cause obstacles to the development of the highway engineering industry.
文摘With the acceleration of urbanization, the soft foundation treatment technology of urban roads has also been developed by leaps and bounds. However, in the construction of municipal projects, the construction scheme should be selected according to the actual situation to ensure the project quality and maximize the social benefits of municipal roads. We should make bold innovations in combination with reality, constantly improve and optimize the treatment methods of soft soil subgrade, continuously improve the scientific analysis ability of soft soil subgrade, enhance the safety and durability of urban roads, and meet the requirements of urban road construction.
文摘With the rapid development of China's social economy, China has also made great progress in infrastructure construction, especially in highway construction in China, which has made great contribution to the development of China's transportation and the improvement of economic development. Road and bridge construction activities are an important part of construction projects. In order to ensure the smooth progress of urban infrastructure construction activities, highway and bridge construction personnel are required to seriously carry out various quality control activities to promote the significant improvement of soft soil foundation construction technology. In the process of highway construction, various types of foundations are involved, among which the construction of soft soil foundation is a typical one. Therefore, in the process of practice, we should fully grasp the corresponding soft soil foundation construction technology and implement various technical points, so as to more effectively strengthen the construction quality of the overall project and provide the necessary conditions for its safe and stable operation. Based on this situation, this paper focuses on the analysis of the main characteristics of soft soil foundation and the application strategies of soft soil foundation construction technology in the process of highway construction. Modern means of transportation put forward higher requirements for the quality of road infrastructure. This paper discusses the details of soft soil foundation construction control technology in highway bridge construction and puts forward some feasible suggestions for improving the construction technology of soft soil foundation. It is hoped that the analysis in this paper can provide some enlightenment for the improvement of highway bridge construction quality.
文摘It is very important to ensure the quality of highway bridge construction and do a good job in soft soil foundation treatment. Only by effectively controlling the overall quality of soft soil foundation treatment can the stability and reliability of highway bridge structure be effectively controlled and the smooth development of highway bridge construction activities be promoted as a whole. In highway and bridge construction activities, the treatment of soft soil foundation is the key. Only by doing a good job in the treatment of soft soil foundation can the service life of the project be effectively prolonged. If the soft soil foundation is not treated, it will cause problems such as road bridge subgrade subsidence and cracks. Only by ensuring the overall quality of subgrade treatment can a solid foundation be laid for the quality control of actual road bridge construction activities.
文摘With the development of Chinas economy, the state has gradually increased the strength of municipal highway engineering construction. The geological environment conditions in different areas are very different. In the process of municipal engineering construction, the construction quality of soft soil subgrade is affected by many factors, such as construction environment, construction requirements and so on, and there are some construction problems such as subgrade settlement. It is necessary to select the construction technology, combine the actual situation of the site, consider various factors, and fully understand the applicable conditions and advantages of various treatment technologies, so as to ensure the actual effect of soft soil foundation treatment and the orderly development of road engineering construction.
