Papers by Keyword: Subgrade Settlement

Abstract: Taking the draw water tunnel of the Jiulong river across railway in Fujian province as the research object,the influence of the subgrade settlement of Yingtan-Xiamen double railway and Xiamen-Shenzhen high-speed railway as a result of the double draw water tunnel excavation is analyzed by FLAC^3D. Through numerical simulation the condition of whether the subgrade is reinforcement and whether have train load on the subgrade, the result of subgrade settlement in both single tunnel perforation and double tunnel perforation is derived. It shows that: the position of maximum settlement is just above the tunnel centerline, the proportion of subgrade settlement caused by the right line excavation is 67.5% and the one caused by the left line excavation is 32.5% when subgrade is unreinforced and there is no train load; the proportion of subgrade settlement caused by the right line excavation is 60% and the one caused by the left line excavation is 40% when subgrade is reinforced but there is no train load. The proportion of subgrade settlement caused by the right line excavation is 63% and the one caused by the left line excavation is 37% when subgrade is reinforced and there is train load. The results fit well with monitoring data and can be used as a reference for similar engineering projects. Currently, with the rapid development of China's economic, the situation of other engineering projects crossing the existing railway line has been increasing. Most researchers is carried out through the way of on-site monitoring to analyze deformation of ground surface and the railway embankment, and then comes up with the safety assessment and displacement control measures of the tunnel construction^[. The common methods of ground surface deformation analysis and prediction contain empirical formula, model test and numerical simulation^[. There are a lot of numerical simulation achievements for new construction crossing the existing railway^[3-, which mainly focused on the embankment settlement for single or multiple tunnel beneath a single railway line. Based on previous studies, this paper analyzes the railway embankment settlement under the condition whether there is reinforced roadbed or not, and whether the two-lane tunnel crosses many railway line with a combination of train load conditions through the method of three-dimensional model, and compares with the measured data to verify the reliability of numerical simulation. 1 Engineering project and its engineering geological conditions

Abstract: The two-dimensional finite element model for subgrade consolidation settlement analysis within soft soil pile is developed using ABAQUS. The numerical simulation on a highway subgrade deformation is performed to study the variation of consolidation settlement and the excess pore water pressure distribution in the central location and the part under centerline of the embankment. The results show that settlement develops gradually with the increasing period of soil consolidation. The excess pore water pressure of deep subgrade soils under embankment centerline rise due to the increased load. After each soil layer was filled, the excess pore water pressure increased in the first and was stable later along with the increase of soil depth. After the embankment soil was filled completely, excess pore pressure dissipated with time developing until the completion of consolidation.

Abstract: Based on the test section on the expressway in Jiangsu, the thesis makes a model and then conducts numerical simulation on the settlement of soft soil subgrade by using FLAC^3D. The author set the filling layer null, and assigns a value to the loaded soil layer according to the construction sequence to realize multi-stage loading. The thesis also analyzes the pore water discharge and foundation deformation when the soil is consolidated. It shows that the simulation result is very close to actual measurement result, and can clearly demonstrate the real situation of settlement.

Abstract: The criterion for residual deformation of Substructure of ballasteless track on railway passenger dedicated line is extremely strict in order to satisfy the safety and comfort requirements of the high-speed train during operation period, urgent need to strengthen the ballastless track lines settlement deformation observation, prediction and assessment technology. Based on Chengdu-Guanxian line, this paper puts forward observation programs of subgrade settlement combined with the characteristics of Subgrade Settlement through the analysis of the influence factors of subgrade settlement deformation and key consideration about the factors of nighttime observation precision. It shows that the monitoring and assessment technology could meet the requirements through the analysis of field data, it can be guidance of railway management departments to make maintenance plan. Some advices provide reference for the monitoring and assessment of high-speed railway subgrade settlement during operation period.

Abstract: Nanjing-Hangzhou Railway Passenger Dedicated Line is a high-speed railway of the speed 350 km/h in coastal soft area without railway track ballast. The settlement of soft foundation is quite great and the strict control standards of the settlement after construction of the high-speed railway that the settlement observation in construction phase is very strict. Through the settlement observation data analysis of Nanjing-Hangzhou Railway Passenger Dedicated Line on-site, the author found that the preloading can rapidly accelerate the settlement of the soft soil subsidence, the settlement is quite great during the embankment construction and the later three months, there is a preloading critical height, the foundation generally does not rebound when load was removed, the settlement trends are consistent with the three-point analysis. These conclusions are certain referential significance for the settlement control of the coastal soft soil area of high-speed passenger dedicated .

Abstract: This paper establishes checking system for subgrade settlement of high-speed railway aiming at technical requirements of analysis and evaluation for subgrade settlement of Chengdu-Guanxian line during operation period. The system starts from design theory of subgrade settlement checking software in the high-speed railway, and elaborates the concept of vertical curve radius in order to determine the value of the security checking indicators. It combines a variety of functions, such as the data management of settlement observation, settlement analysis and prediction, data reports automatically generated.at the same time, the system is full-featured, friendly interface and easy extension. Engineering practice shows that the system has a good applicability and stability for the settlement deformation assessment. It provides a platform for information management and scientific decision-making of settlement assessment.

Abstract: Traffic safety in existing railway has strict demands to the subgrade deformation, and the subgrade deformation caused by foundation pit excavation should be under the limit value. In this paper, steel sheet pile cofferdam supporting system is introduced, as well as its construction process. 2D numerical simulation is adopted to simulate the construction process, the deformation of subgrade at different cases are discussed. At last, the field monitoring data is provided to verify the validity of supporting system and numerical simulation results . Research results indicate that steel sheet pile cofferdam supporting method can well control the subgrade deformation, and can be took as a precedence technique in similar engineering. To ensure the traffic safety, it’s necessary to prevent the trains crossing near the excavation, and the train speed should be limited.

Abstract: The solar power supply system was studied for remote automatic monitoring device on subgrade settlement. Gave the detailed design formula and circuit principle diagram, the independent solar power supply system was designed that is stable, reliable and can get a variety of output voltage. It was successfully applied to outdoor monitoring devices of subgrade settlement, the results show the solar power supply system has a high stability and efficiency, and absolutely meet the needs of project applications.

Abstract: The control of subgrade settlement has been the main influencing factor on highroad pavement quality, so estimating settlement amount after construction based on designed embankment height and planning the construction filling height beforehand through the settlement prediction is a very important work. Because of the complex coupling properties and high nonlinear characteristics of the factors influencing foundation settlement, a soft-roadbed settlement prediction model based on RBFNN (Radial Basis Function Neural Network) is proposed, combining the global fitting properties of RBFNN. The analysis shows that the model owns good fitting property and high prediction precise, and certain practical value.

Abstract: Bridge pier moving is not a popular problem in soft clay ground section of highway but this problem is found in parts of bridge piers in Leqing section of NING-TAI-WEN expressway, which is used plastic drain bar to deal with the soft clay ground. By monitoring the bridge pier displacement and the data getting from observation of subgrade settlement this paper establishes the relation curve of subgrade settlement and bridge pier displacement and, by analyzing the characters of soft clay ground and the force acting on pile foundation, gets the reasons and presents suggestions to solve the problem.