The Accident Analysis And Processing About Uneven Settlement Of A Framework Structure In Collapsible Loess Areas

Loess has collapsibility,in the natural state (the guanzhong loess tableland area average water content is less than20%), its porosity is larger,the bearing capacity is relative taller;With the increase of water content or in saturated state,its bearing capacity will be greatly reduced and will happen to produce wet sinking under certain pressure.in the collapsible loess areas, uneven settlement have mostly occured at the foundation of the frame structure and mixed structure building after being used a few years.Uneven settlement will lead to wall cracking of the upper structure,seriously will cause tilt or even collapse of the building.After the accident of uneven settlement of a frame structure, the geological survey has being conducted, the inspection and appraiser has being carried out,and further more the causes of uneven settlement building is being analyzed, the application of the quicklime pile in reinforcing foundation is expounded in detail in the collapsible loess region.In this paper,combined with the engineering accident case of a frame structure building in Shanxi Province, the whole process of treatment of accident caused by uneven settlement are analyzed.The main contents are as follows:(1)The work process of reinforcement and reconstruction for building structure,as well as the method of structure reliability evaluation and the basic principles of reinforcing foundation using quicklime pile is described in detail.The calculation of quick lime dosage and the calculation and determination of quick lime expansion coefficient as well as the calculation of the void ratio of soil are summarized in this paper.(2) The engineering investigation has been conducted after the accident,finding out the geotechnical conditions of dormitory building.The engineering geological characteristics in this building site are described in detail.The engineering properties of loess, hydrogeological and foundation soil corrosive,the uniformity of the foundation soil is evaluated respectively.At last, the advice on accident treatment and foundation reinforcement are given. (3) The process of the uneven settlement is elaborated in detail.The results of the inspection and appraiser has been carried on the in-depth analysis.The cause of the uneven settlement accident are analyzed in detail.(4) The selection of quicklime pile reinforcement scheme,the design and construction of reinforcement has been analyzed thoroughly,the theoretical calculation is made on how to determine the number of lime pile,the several key process of the construction we should pay attention to are described in detail.The monitoring data of subsidence in the construction process and after the construction being completed is analyzed. the physical and mechanical properties of the foundation soil before and after construction were analyzed by comparison.