The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-s...The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-softening, ideal elasto-plastic and work-hardening, a universal tri-linear load transfer model is suggested for the development of side and tip resistance by various types of soil (rock) with the consideration of sediment at the bottom of the pile. Based on the model, a formula is derived for the relationship between the settlement and load on the pile top to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip. A close agreement of the calculated results with the measured data from a field test pile lends confidence to the future application of the present approach in engineering practice.展开更多
Effect of soil displacement on friction single pile in the cases of tunneling,surcharge load and uniform soil movement was discussed in details with finite element method.Lateral displacement of the pile caused by soi...Effect of soil displacement on friction single pile in the cases of tunneling,surcharge load and uniform soil movement was discussed in details with finite element method.Lateral displacement of the pile caused by soil displacement reached about 90% of the total displacement,which means that P-Δ effect of axial load can be neglected.The maximum moment of pile decreased from 159 kN·m to 133 kN·m in the case of surcharge load when the axial load increased from 0 to the ultimate load.When deformation of pile caused by soil displacement is large,axial load applied on pile-head plays the role of reducing the maximum bending moment in concrete pile to some extent.When pile is on one side of the tunnel,soil displacements around the pile are all alike,which means that the soil pressures around the pile do not decrease during tunneling.Therefore,Q-s curve of the pile affected by tunneling is very close to that of pile in static loading test.Bearing capacities of piles influenced by surcharge load and uniform soil movement are 2480 kN and 2630 kN,respectively,which are a little greater than that of the pile in static loading test(2400 kN).Soil pressures along pile increase due to surcharge load and uniform soil movement,and so do the shaft resistances along pile,as a result,when rebars in concrete piles are enough,bearing capacity of pile affected by soil displacement increases compared with that of pile in static loading test.展开更多
Based on Mindlin stress solution, a numerical computational method was proposed to calculate the stresses in the ground induced by side friction and the resistance of Y-shaped vibro-pile. The improved Terzaghi's a...Based on Mindlin stress solution, a numerical computational method was proposed to calculate the stresses in the ground induced by side friction and the resistance of Y-shaped vibro-pile. The improved Terzaghi's and ЪерезанцевВГ's methods for ultimate bearing capacity evaluation were proposed by considering the stress strength induced by friction resistance at pile head level of Y-pile. A new method to calculate the ultimate bearing capacity of Y-pile was also proposed based on the assumptions of soil failure mode at the tip of Y-pile and the use of Mohr-Coulomb soil yield criterion and Vesic compressive correction coefficient with the induced stresses in the ground. Based on the comparisons with the field static load test results, it is found that the improved Terzaghi's method gives higher ultimate capacity, while the other two methods shows good agreement with the field results.展开更多
CFG pile (i.e., pile constructed by granular materials of cement, fly-ash and gravel) composite foundation is applied in subsoil treatment widely and successfully. In order to have a further study of this kind of subs...CFG pile (i.e., pile constructed by granular materials of cement, fly-ash and gravel) composite foundation is applied in subsoil treatment widely and successfully. In order to have a further study of this kind of subsoil treatment technology, the influencing factors and calculation methods of the vertical bearing capacity of single CFG pile and the CFG pile composite foundation were discussed respectively. And based on the obtained solutions, effects by the cushion and measurements to reduce negative friction area were analyzed. Moreover, the developing law of settlement and bearing capacity eigenvalue controlled by the material strength with the increase of load were given for the CFG composite foundation. The in-situ static load test was tested for CFG pile. The results of test show that the maximum test load or half of the ultimate load is used from all the points of test, the average bearing capacity eigenvalue of single pile is 390 kN, and slightly greater than the design value of bearing capacity. The bearing capacity eigenvalues of composite foundation for 3 piles are greater than 300 kPa, and the mechanical properties of CFG pile composite foundation are almost identical in the case of the same load and cushion thickness. The pile-soil stress ratio and the load-sharing ratio can be adjusted through setting up cushion thickness.展开更多
The construction process and load-bearing behaviors of Cast-in-place concrete thin-wall pipe piles are analyzed based on its application on Yantong Expressway Project. The low strain test, static load test and field e...The construction process and load-bearing behaviors of Cast-in-place concrete thin-wall pipe piles are analyzed based on its application on Yantong Expressway Project. The low strain test, static load test and field excavation were also carried out, and the bearing capacity of the new pile can meet the requirements of design. With the increase of pile diameter, the bearing capacity is increased. The settlement of composite foundation is decreased, when the replacement ratio of pile is increased. The test results also show that the load carried by inner soils is neglectable. According to the tests and application, it can be concluded that the new type of pile is convenient to construction with high bearing capacity and reliable quality, which has great potential in practical engineering.展开更多
文摘The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-softening, ideal elasto-plastic and work-hardening, a universal tri-linear load transfer model is suggested for the development of side and tip resistance by various types of soil (rock) with the consideration of sediment at the bottom of the pile. Based on the model, a formula is derived for the relationship between the settlement and load on the pile top to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip. A close agreement of the calculated results with the measured data from a field test pile lends confidence to the future application of the present approach in engineering practice.
基金Project(51208071)supported by the National Natural Science Foundation of ChinaProject(2010CB732106)supported by the National Basic Research Program of China
文摘Effect of soil displacement on friction single pile in the cases of tunneling,surcharge load and uniform soil movement was discussed in details with finite element method.Lateral displacement of the pile caused by soil displacement reached about 90% of the total displacement,which means that P-Δ effect of axial load can be neglected.The maximum moment of pile decreased from 159 kN·m to 133 kN·m in the case of surcharge load when the axial load increased from 0 to the ultimate load.When deformation of pile caused by soil displacement is large,axial load applied on pile-head plays the role of reducing the maximum bending moment in concrete pile to some extent.When pile is on one side of the tunnel,soil displacements around the pile are all alike,which means that the soil pressures around the pile do not decrease during tunneling.Therefore,Q-s curve of the pile affected by tunneling is very close to that of pile in static loading test.Bearing capacities of piles influenced by surcharge load and uniform soil movement are 2480 kN and 2630 kN,respectively,which are a little greater than that of the pile in static loading test(2400 kN).Soil pressures along pile increase due to surcharge load and uniform soil movement,and so do the shaft resistances along pile,as a result,when rebars in concrete piles are enough,bearing capacity of pile affected by soil displacement increases compared with that of pile in static loading test.
文摘Based on Mindlin stress solution, a numerical computational method was proposed to calculate the stresses in the ground induced by side friction and the resistance of Y-shaped vibro-pile. The improved Terzaghi's and ЪерезанцевВГ's methods for ultimate bearing capacity evaluation were proposed by considering the stress strength induced by friction resistance at pile head level of Y-pile. A new method to calculate the ultimate bearing capacity of Y-pile was also proposed based on the assumptions of soil failure mode at the tip of Y-pile and the use of Mohr-Coulomb soil yield criterion and Vesic compressive correction coefficient with the induced stresses in the ground. Based on the comparisons with the field static load test results, it is found that the improved Terzaghi's method gives higher ultimate capacity, while the other two methods shows good agreement with the field results.
基金Project(08JJ3111) supported by the Natural Science Foundation of Hunan ProvinceProject(08B025) supported by Scientific Research Fund of Hunan Provincial Education DepartmentProject(2006AA11Z104) supported by the National High-Tech Research and Development Program of China
文摘CFG pile (i.e., pile constructed by granular materials of cement, fly-ash and gravel) composite foundation is applied in subsoil treatment widely and successfully. In order to have a further study of this kind of subsoil treatment technology, the influencing factors and calculation methods of the vertical bearing capacity of single CFG pile and the CFG pile composite foundation were discussed respectively. And based on the obtained solutions, effects by the cushion and measurements to reduce negative friction area were analyzed. Moreover, the developing law of settlement and bearing capacity eigenvalue controlled by the material strength with the increase of load were given for the CFG composite foundation. The in-situ static load test was tested for CFG pile. The results of test show that the maximum test load or half of the ultimate load is used from all the points of test, the average bearing capacity eigenvalue of single pile is 390 kN, and slightly greater than the design value of bearing capacity. The bearing capacity eigenvalues of composite foundation for 3 piles are greater than 300 kPa, and the mechanical properties of CFG pile composite foundation are almost identical in the case of the same load and cushion thickness. The pile-soil stress ratio and the load-sharing ratio can be adjusted through setting up cushion thickness.
基金Project(50679017) supported by the National Natural Science Foundation of China
文摘The construction process and load-bearing behaviors of Cast-in-place concrete thin-wall pipe piles are analyzed based on its application on Yantong Expressway Project. The low strain test, static load test and field excavation were also carried out, and the bearing capacity of the new pile can meet the requirements of design. With the increase of pile diameter, the bearing capacity is increased. The settlement of composite foundation is decreased, when the replacement ratio of pile is increased. The test results also show that the load carried by inner soils is neglectable. According to the tests and application, it can be concluded that the new type of pile is convenient to construction with high bearing capacity and reliable quality, which has great potential in practical engineering.
