Research Of Crack In Mass Concrete Baseplate Restricted By Pile Foundation

With the development of the high building,mass concrete baseplate is used widely more and more. With the application of mass concrete structure, harmfulness of cracks of mass concrete structure aroused the attention of designers and construction workers. The crack of mass concrete baseplate is a common problem to engineering field, by now, people have not yet found a reliable way to solve the problem, but have found out two main reasons of crack problem:One is that the internal temperature stress of of the structure is caused by temperature differences between inside and outside of structure and daily temperature changes,the other is that the tensile stress is caused by concrete baseplate shrinkage under restriction of piles and foundation soil, so this article is concentrate on analyzing how to control cracks from this two aspects.In this article, author mainly analyses the concept of mass concrete and the crack, crack reason and the harmfulness of crack. Also, author gives a brief summary of the research status in this filed at home and abroad, and from the concrete materials, structural design and constructions ect, aspects, the author gives a summary of control methods of the mass concrete baseplate temperature cracks; Analysis the concept of the mass concrete temperature field, use software ANSYS to do the thermal structure coupled simulation to the structure, and analysis the main influence factors of the mass concrete temperature stress.This paper focuses on constraints of pile to the mass concrete and influences of constraints on the concrete baseplate cracks.The constraint size affects internal temperature stress of the concrete, and constraint size has relationship with the pile diameter, spacing, and the structures between the pile and baseplate. By adjusting the pile diameter, spacing, and setting rubber pads in the contact place between pile and baseplate to control the constraint, meanwhile the author uses software ANSYS for simulation, by adjusting pile diameter, spacing, and length conditions to observe the constraint of pile to the baseplate. By the model simulation, we get the temperature stress by the constraint of the pile to the baseplate.We can see that constraint size effect is obvious to the baseplate from simulation and analysis. Through the theory we prove the rationality of the result.It is reasonable to control baseplate stress and achieve the purpose of controlling the cracks by controlling constraints size. The research results in this article provide a useful reference to prevent mass concrete temperature cracks.