| The prestressed concrete tubular pile is one kind of new appearing type in recent years. This tubular piles comparing with traditional foundation have greater superiority in consolidating in foundation ,time limit for a project, construction costs and environmental protection, therefore it is had got extensive use in the project. But the stratum's reasons and pole body's defects lead to a tubular pile's bearing insufficient thing often having happening. It is occured that the body makes use of the back grouting technology to rise the foundation's bear and reinforce the pile's bear frequently. But the prestressed concrete tubular pile of back grouting gets strain-strain characteristic property studied very little and it has restricted the extension of the new technique' development. Based on the working of predecessor and through interior analogue test and numerical value analysis, the stress-strain characteristic of soil that is surrounded tubular piles on back grouting is studied. The main part of this book is following:Firstly, the main body of a book has introduced the prestressed concrete tubular pile's merit, defect, proper stratum, the characteristic of our country development and advanced progress of home and abroad research. Based on all above content, the author suggest the main body of the book.(1) The tubular pile and the back grouting on tubular pile's axis decays strenuously step by step along depth direction, and it is assumed "the inverted triangle " distribution .The upper body axis force is greater than lower part. The axis force rate decay slowlier after grouting. This is cause of the side friction increasing after the pole head expanded.(2) The tubular pile and back grouting on tubular pile 's ratio of the coner pile ,the border pile and inner pile is 1.28: 1.13: 1 and 1.38: 1.16: 1 respectively. It can be obtained the resistance on the top of pile enhanced 25%, 19% , 16%. Tip resistance is increasing because of the stress redistribution.(3) The peak value of the side friction force are changed with the position of grouting, i.e. coner pile >border pile >inner pile. The peak value of the side friction force enhanced 8%.And the side friction force improves unobviously after grouting.(4) The tubular pile 's tip resistance of the coner pile, border pile , inner pile after grouting enhanced 2.35 times ,2.18 times and 1.90 times. The tip resistance improves obviously after grouting and the latter is 1.19 times of the former.(5) The peak value of soil pressure is 138 kPa and the peak value of soil pressure after grouting is 164 kPa when the size of the cap keeps constant. It can be seen that the bearing after grouting is enhancing. It is assumed that soil resistance is a decreasing trend along pole body, namely that soil resistance is diminished when the pole body is imbed deeplier.(6) After grouting, the settlement and the bearing capacity both are enhancing. The limit bearing is 40 KN and 48 KN grouting front and back. The bearing after grouting has improved 20% strenuously and it can be known the back grouting has obvious effect to improve strenuously.Finally, making use of the ANSYS finite element method software to build analysis model and meeting the main specifically for pole body stress-strain , pole cycle soil stress-strain, load- settlement relation has carried out analysis and has verified the accuracy testing that.
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