Characteristics Analysis And Improvement Research On Static Pressure Pile Machine

The static pressure pile machine that is one kind of foundation engineering construction equipments takes the self-weight and the hydraulic pressure as the power to construct the prefabricated piles. It is mainly applied to the soft foundation for the pile foundation construction. Compared with other traditional pile-engineering machinery, the static pressure pile machine has many merits which is no pollution, no vibration, low noise and so on. However, in the actual application process, the static pressure pile machine has many flaws, for example, the power match does not conform to the actual conditions, the pile-clamp mechanism does not clamp the pile firmly and so on. In project construction, the application of pile foundation is extremely widespread. The building quality is directly related to the reliability of pile foundation. Simultaneously with development of our country'economy and enhancement of the people's lives level, the demands for building construction become more and more higher, so the static pressure pile machine is guided directly to the high performance direction to develop.The object that is researched in this article is the 100t static pressure pile machine. The main problems which appear in the practical application process of the static pressure pile machine are analyzed and improved. The goal lies in enhancing performance of the static pressure pile machine, satisfying the power match requirement, guaranteeing the quality of pile foundation, providing the theory for forming the great-ton static pressure pile machine.(1) The pile-soil interaction process is analyzed, the soil layer structure that suits to the static pressure method is chosen and the soil resistance is calculated. The formula of pile-stress that comes from the soil is deduced when the pile and the soil have relative motion and the pile-press stability of the static pressure pile machine is analyzed by using that formula in the fourth chapter. On the basis of theanalysis of soil physical property, the soil that suits to the static pressure pile machine is classified and the soil layer structure that suits to the static pressure method is chosen. The soil resistance is calculated on the basis of the selected soil layer structure and the soil-pile force curve is obtained. The constant power regulation characteristics of the static pressure pile machine are researched on the basis of the curve in the third chapter.(2) The constant power hydraulic system of the static pressure pile machine is researched. The constant power hydraulic system is taken as the research object on the basis of analyzing working performance of hydraulic system between the constant flow and the constant power. Because non-synchronization of the pile-press cylinders may exists in the constant flow hydraulic system, two flow divider valves are added in the original hydraulic system to control the opposite pile-press cylinders for their synchronization, the goal is to avoid reducing the quality of pile foundation which is caused by the non-synchronization of the pile-press cylinders. In order to facilitate reequipment, the installation and geometry size of the original pile-press cylinder are not changed and on the basis of it the rated pressure is chosen. The constant power variable displacement pump is chosen through the rated pressure and the analysis of the performance of the constant power hydraulic system. The adjusted output pressure of the variable displacement pump is chosen and analyzed. The variable displacement pump output power enters into the constant stage when the pressure value arrived at 6.36MPa. The pressure value satisfies the performance requirement of the constant power hydraulic system.(3) The pile-hung stability and the pile-press stability of the static pressure pile machine are researched. The difference between anti-inclined moment and inclined moment is calculated for the static pressure pile machine under the non-counter-weight condition. The static pressure pile machine is the easiest to lose stability when the angle in the horizontal plane between the crane arm and the long ship is 118degree. The degree is taken as the parameter and the inertia force of theobject which is carried by the crane is considered. The change about the force of the long ship that comes from the ground is simulated and the stability when the crane is carrying object is judged by the force whether the force value is negative or not. The analysis result indicated: as long as the hanging quality is in fixedscope, even if the pile machine center-of-gravity position is changed by the crane arm rotation and the influence of the inertia force is considered, all cannot cause the pile machine losing the stability under the non-counter-weight condition when the pile machine is hanging the piles. Because of big difference of soil layer structure in different areas, the sole soil structure is used to calculate the anti-inclined moment when the stability of the static pressure pile machine is analyzed. Because every sole soil layer produces the smallest moment that is bigger than the pile machine inclined moment. The static pressure pile machine may only break the pile to lose stability in all soil layers which suit to pile machine. To avoid breaking the pile, different pile types are matched to different pile pressure. Accordingly, the ultimate pile pressure is obtained to ensure the pile machine not to lose the stability.(4) The shortcomings of the traditional pile-clamp mechanism are summaried and analyzed. The pile-clamp mechanism is improved. The force which acts on the pile in the pile-press process is calculated and the reason why the pile is damaged is analyzed. In view of these shortcomings, the performance requirement about clamping the pile firmly and no damage of the pile in the pile-clamp process are proposed. The improved pile-clamp mechanism can satisfy the requirement: the force is added to clamp the pile, the pile stress is reduced and the return trip must be smooth. Because the different movement between the wedge block and the pile-clamp block in the improved pile-clamp mechanism may cause the damage of their surface,so the kinematics and dynamics simulation are carried on to gain the conclusion which is that the wedge block and the pile-clamp contacts in the entire working process.