Research On The Post-construction Shallow Reinforcement Technology Of Composite Foundation

Recently, composite foundation has been widely used in the engineering construction,with advantages of high bearing capacity, small settlement, good social and economicalbenefits, all of which make it become an effective modern method to strengthen softfoundation. However, the research on the basic theoretical knowledge of compositefoundation often turns out to incompatible with its development of engineering practice. Morespecifically, there are plenty of unscientific and unwarranted points for the traditional designtheory of composite foundation，such as inevitable properties of blindness and inaccuracy,lacking the initiative control and feedback design etc. Aiming at above questions, a newtechnology---the post-construction shallow reinforcement technology of compositefoundation is proposed. Meanwhile, more details and analysis about this new technology areconducted, which provide technical and theoretical supports for its faster development in theengineering practice.According to the characteristic that the bearing capacity of soil between piles depends onthe strength and stiffness of the soil in the shallow place, this new method about compositefoundation is proposed. Combining numerical analysis methods with the engineering practice,the bearing properties of composite foundation which has been gone throughpost-construction shallow reinforcement is analyzed by the finite element analysissoftware-ADINA. Besides, effects of reinforcement depth and reinforcement materialproperties on the bearing properties are analyzed. Some results are shown as below:(1)According to the exist theory of composite foundation, the basic idea of thepost-construction shallow reinforcement technology of composite foundation is summarized:The whole construction process of composite foundation is divided into two parts, theconstruction of piles and the post-construction shallow reinforcement of soil between piles,respectively. Considering the fact that this reinforcement will definitely improve the overallbearing capacity, the design requirements of bearing capacity for piles could be reduced to some extent. After the construction of piles, field static load test of piles are conducted to getsome results which can be used for the design and construction of the post-constructionshallow reinforcement. Based on above ideas, Surface compaction、Shallow soil–replacing、Setting gravel short wall、 Insertting short pile、 Setting tube-Geogrids、 Groutingreinforcement、Horizontal direction multi-layer reinforced.(2)This article will take a post-construction reinforcement method of shallowsoil-replacing which is used in granular pile composite foundation as example and useADINA software to take numerical experiment and analog computation for thepost-construction surface reinforcement of single pile or group piles composite foundation.Afterward, this article will describe the outcome of surface reinforcement of single pile orgroup piles composite foundation in different condition of reinforcement depth andreinforcement material and will contrast the composite foundation’s integral deformation,displacement, stress and developments in plastic zone under all kinds of cases. Finally, thisarticle will extract numerical calculation outcome and draw curves representing therelationship of sedimentation and loads or the relationship of Pile-soil stress ratio and loads.After analysis, the result show that with the increase of reinforcement depth and elasticitymodulus,the bearing capacity will increase while the settling volume will decrease. Inaddition, the choose of the best reinforcement depth and the best reinforcement materialshould be taken into consideration. In short, by doing this, we can prove that thepost-construction surface reinforcement could increase the carrying capacity and decrease thesettling volume of composite foundation.(3)By analysis the case of the post-construction surface reinforcement method ofgranular pile composite foundation, the author find that by choosing proper reinforcementmaterial and reinforcement depth, the strength and rigidity of soil among piles will increasewhich will give rise to the lateral extrusion pressure of the soil among piles to improve thebearing capacity of piles and finally increase the bearing capacity of composite foundationand decrease its settling volume. Thus, in the practical engineering, the designer can adjustbearing capacity of composite foundation by changing reinforcement material andreinforcement depth in order to meet the design requirement.The post-construction surface reinforcement technology of composite foundation relatedin this treatise could be used in foundation reinforcement, underpinning, remedy and otherengineering practices.The numerical analysis in this article could provide technical guidancefor its better used in practical engineering, which is significant in aspect of theory andpractice.