Study On Characteristics Of Bearing Capacity Of Cast-in-situ Branched Bored

With the development of new technology and the demands of the in situ engineering,pile foundation has been basic foundation type widely used in different constructions,especially cast-in-situ bored pile is currently dominated and constructed widely.In practical,the area of loaded bottom will be influenced by equipment,site and technological level,this leads to the weakness of bearing capacity of the soil.Furthermore the friction of pile side is significantly reduced by the construction process.The bearing capacity of single pile which relative to pile body material failed to give full utility that influenced by construction equipment,site,technological level and ability.Therefore,the after filling pile grouting process has been proposed to improve the bearing capacity of single pile.In fact,the method of existing grouting craft does not make full use of pile lateral soil,however,it has large discreteness.I this paper,a new post-grouting craft is proposed with cast-in-situ bored brand pile as the new pile type.An expanding head at the pile end and some branch at the different height of pile are formed by presetting standpipe and horizontal straight pipe in the grouting reinforcement cage.This pile can further develop the bearing function of the soil and increase the pile bearing capacity.The research contents are discussed as follows:1.The existing grouting process and characteristics have been concluded,and the discreteness and reliability of the bearing capacity of pile after grouting have been analyzed and the improvement of grouting process is proposed.2.The new construction process and technology of cast-in-situ bored brand pile is proposed.The prefabricated type of grouting tube,the method of construction,the selection principle of grouting materials and grouting layers and the control of grouting pressure have been analyzed.The common problems and solutions of this construction process have been concluded.3.The enhancement effect of bearing capability of cast-in-situ bored brand pile and the expanding head of pile end have been further explored,as well as the function of brand pile to reduce the settlement with the combination of mechanisms of osmotic grouting and consolidation grouting.The reliability of this research technique has been preliminary discussed refer to pose grouting theory and related calculation method.4.The structure and soil function characteristics of cast-in-situ bored brand pile have been demonstrated by an in-situ test data of pile end grouting engineering and the calculation formula of bearing capacity of grouting pile end,and combining with the theory of load transferring.Hereafter,the calculation formula of bearing capacity of this new pile is derived and modified by conducting the simulation with Ansys.5.The numerical simulations of cast-in-situ bored brand pile under different loads have been conducted based on Ansys.The bearing principle has been analyzed according to the numerical results.The influences of pile diameter,the distance of pile spacing plates,the elastic modulus,friction angle,cohesion and friction coefficient on the bearing capacity of cast-in-situ bored brand pile have been analyzed,and the engineering design suggestion has been given.Moreover,the enhanced characteristics of bearing capacity of cast-in-situ bored brand pile and the influence area of brand pile are discussed and summarized preliminarily.