Bracing Characteristics Of Jet Mixing Anchor Pile

In recent years,a new type of retaining structure has been put forward in the soft soil foundation pit--jet mixing anchor pile.The technology has been developed to anchor steel strands in large diameter jet grouting piles in soft foundations,and the piles are prestressed by the steel strands to get big pullout resistance.It can provide sufficient space for the construction,but also have sufficient rigidity to control the deformation of the foundation pit.In addition,the development and application of recyclable bolt technology achieved the re-use of strand.The practical application of this technique in Shanghai,Wenzhou,Tianjin and other soft soil areas shows that the technology can save the construction period and reduce the engineering cost,but its theoretical research is still lagging behind the engineering practice.In order to meet the needs of engineering practice in design and calculation,this thesis will research the load transfer mechanism and deformation characteristics of a single jet mixing anchor pile,and the deformation of the foundation pit supported by this technology.In this thesis the main work and initial achievement include:(1)By using ABAQUS software,a model of the single jet mixing anchor pile under tension was established.The deformation of cross sections of the model with different amounts of strands and the effect of plate on deformation of the jet mixing anchor pile have been studied.The distribution of axial force along the strand and the side friction along the cement mixing pile were worked out respectively.The results reveal the mechanics characteristics and failure mechanism of the jet mixing anchor pile.(2)Based on the assumption that the supporting wall(pile)is regarded as the elastic cantilever beam with fixed base,the Macaulay’sFunction is used to calculate the lateral deformation of supporting wall(piles)supported by jet mixing anchor pile,while considering the soil stratification and the appropriate earth pressure model.In addition,a hybrid method for determining the lateral deformation of supporting piles has been proposed.(3)Adopting the lateral deformations of the retaining structures for predicting the distribution of ground settlement behind the bracing wall(piles),the normal distribution has been improved and the P-III curve has been introduced to fitting the ground surface settlements JK3 E software,normal distribution,skewed distribution and P-Ⅲ distribution have been used to calculate the ground settlement near the foundation pit supported by jet mixing anchor pile,and the results from four kinds of methods are comparatively analyzed.