Theory And Practice Of Forced Settlement Rectification For Low-rise Masonry Building

Taking two-way inclined deformation of a low-rise residential building in Lanzhou caused by uneven settlement foundation as the engineering background, the essay analyses the inclined reasons, aimed at the features of low-stress and weak rigidity building ,studys the inherent characteristics of collapsible loess,determines the hole's spacing, the hole's height and other parameters with plastic theory,designs technical proposal for forced settlement rectification.By using dynamic design idea, after four circulations, consuming 90 days, we successfully realize the two-way inclination-rectifying of the residential building.Engineering conclusions indicate that:(1) In the forced settlement rectification for low-rise masonry building,in order to realize harmonious deformation between superstructure and foundation,proper technology should be adopted under the guidance,such as small aperture, small space,etc;(2) Aimed at collapsible loess foundation, in three kinds of the forced settlement technology, both stress relief method and additional stress method have a poorer rectifying effect,but stiffness softening method makes a notable impact on rectification.It provides a useful reference for guiding the engineering practice.(3) Forced settlement rectification is a dynamic design process, should adjust each hole's injection to have every place of foundation sunk according to certain geometrical proportions.Monitoring has an very important role in forced settlement rectification ,so we should observe timing and adjust momentarily;(4) For two-way rectifying ,we should pay full attention to construction techniques such as the selection of hole deep, water injection mode and water injection rate;The essay establishes the 3-d finite element model for forced settlement rectification with ANSYS finite element analysis software,analysis the effects of the slot depth in the stress relief method on the rectification results,determines the height of horizontal drilling in the stress additional method. Analysis results indicate that: in the stress relief method,with the increase of slot depth, settlement amount and the stress value of each point were increasing, after 7m, one side and another side kept pace increase, both sides'settlement began to remain unchanged. The hole's height in the stress additional method is determined to the distribution of foundation stress.Under the 2.0m depth of foundation, the distribution of foundation stress become more and more even.The forced settlement technology reflects better application in low-rise masonry building. ANSYS finite element software provides a theoretical analysis platform for the forced settlement rectification technology, brings theoretical guidance and technical support for the forced settlement rectification technology.