Analysis And Reinforcement Of Concrete Cracking Of A Basement In Hainan Province

With the continuous development of our economy,human society’s demand for land surges day by day,and buildings of various types and structures emerge endlessly.In order to maximize the utilization of space,people’s attention gradually extends to underground space,and high-rise buildings with one or even multiple layers underground can be found everywhere.Concrete structure is one of the most common and widely used structural forms in existence.Because the concrete material is brittle material,has the characteristics of tensile strength bottom and high tensile strength,it is easy to cause the opening and cracking damage,leading to a series of structural safety problems,and the various hazards can not be underestimated.Concrete cracks are one of the most common damage to concrete.The existence of some cracks will affect the integrity of the structure,reduce the stiffness of the building,affect the bearing capacity of the structure,and harm many.In view of the above background,this paper introduces the concrete cracking background of a project basement in Hainan Province.The main work and research achievements of this paper include:(1)In Hainan Province,a project basement concrete crack damage as the background,through the collection of data and literature,the investigation of the accident and crack damage analysis,and through the construction investigation,bearing capacity analysis,anti-floating check calculation analysis of the main reasons for the crack(1)Anti-buoyancy measures are not in place: when the basement is damaged,the 1.5m backfill soil on the top of the damaged area is not completed,resulting in the dead weight of the building structure can not resist the buoyancy of groundwater.Under the condition that the anti-buoyancy measures are not completed,the waterproof board bears too much water buoyancy,and the bottom plate is uplifted and deformed,and the structural members appear cracks.(2)The stop time of precipitation does not meet the design requirements: the site drainage system has not been completely constructed and the precipitation well has not been repaired,which violates the design requirements.As a result,the site drainage system cannot work normally during the rainy season,the rainwater cannot be discharged in time,and the water level around the exterior wall of the basement rises,causing the basement to rise and damage.(2)Check the crack width of typical beam and column members under normal use state.Through theoretical calculation,it is verified that the crack width of structural members under normal use state is in line with the requirements of relevant specifications.(3)With the help of Midas FEA NX finite element analysis software,the "well" shaped area formed by four concrete columns at the cracked site of the basement,the roof and bottom plates of the corresponding parts of the column and half of the column overhanging beam was selected as the typical analysis area,and the numerical simulation calculation was carried out.Under the influence of groundwater level,the development of concrete and steel stress and crack under different water buoyancy is analyzed,and the correlation between water buoyancy and crack development due to the change of groundwater level is verified.The following conclusions are reached(1)When the groundwater level reaches above the raft 2.1m(the design water level is1.84m),cracks begin to appear on the concrete roof and foundation raft,and when the water level reaches 2.4m,the cracks begin to expand greatly.(2)Raft cracks are mainly distributed in the more empty part between the column and the column,where there is no column constraint,so under the buoyancy is the weak part of the cracking.The roof crack is mainly distributed in the column and the roof joint part,where the roof is subjected to the column punch cutting action,and produce cracks.(3)The column crack mainly occurs at the column end,and the beam crack mainly occurs at the junction between the beam and the roof,which is because the beam-column joint is easy to be damaged under the action of pressure.(4)The calculated crack position is also highly consistent with the measured crack distribution area.(4)According to the engineering case of basement concrete cracking in Hainan Province,beams and columns are reclassified and labeled according to serious crack damage,general crack damage and slight crack damage,and corresponding crack reinforcement design or crack treatment scheme is given.Then,the bearing capacity of typical beam and column members with severe crack damage is checked respectively,and the feasibility of the reinforcement design is verified by theoretical calculation...