| Pile foundation is widely used in the fields of industry, port, railway and high buildings with the development of construction business. Compared with the pre-formed pile, the bored pile is developed rapidly for the virtues such as less noise, little librations and fewer effects on the environment during the construction. Because of the virtual earth under the pile ending hard to clean, the ending bearing is seldom worked sufficiently, which leads to ultimate bearing capacity and settlement problems. In this case, the injection grout is a preferably method to improve the hearing capacity and reduce the settlement of bored pile. When there is a pressure chamber under the pile ending, the relationship among grouting pressure, soil under pile ending and the amount of grouting is still confused. The study on grouting in different groundsill, maximum radius of grout and the shape is still the little research.The FLAC3D is used to simulate the injection grout under the pile ending. The working mechanism of bored pile post grouting and the grouting technology are dissertated in the first. And then, measured data is analyzed to ascertain the feasibility of numerical simulation. The enlarged radius, stress of ending soil and area of compaction zone are also discussed. At last, the influencing factor of enlarged radius is ascertained and simulated. The main conclusions are:1. The enlarged shape is bear on character of ending soil. The ratio of vertical displacement and horizontal displacement is amplified when the elasticity is decreased. The shape of ending hole is gradually turned into spheroid from ellipsoidal approximately.2. Vertical and horizontal displacement of ending hole are both increased with the decrease of internal friction angle. When the angle is between 25°nd 30°, the displacement decreased sharply; when bigger than 30°,the displacement changed slowly, and the ratio of them intends to diminish.3. The enlarged radius increased with grouting pressure. It and be seen from the displacement picture that displacement is decreased when far.4. Displacement of the pile top is influenced by the pile length and grouting pressure. The pressure can not be too big when the bored pile is less than 10m, or a upward displacement will be seen on the pile top.The Vertical and horizontal displacement of ending hole are both decreased with the increase of pile length when the soil and grouting pressure is constant. |
