Safety Accident Analysis And Countermeasures Of Over Dangerous Projects

In recent years,China’s adherence to the policy of "safety first,prevention first,comprehensive treatment" has achieved initial results.The situation of construction safety production has been further improved,and the overall situation has gradually stabilized.However,production safety accidents still occur from time to time.For example,two major safety production accidents occurred in Yangzhou in 2019,namely,the "3.21" attached scaffold falling and the "4.10" deep foundation pit collapse,which had a relatively bad impact on the whole province and even the whole country.In this paper,according to the specific characteristics of construction in Yangzhou area,four kinds of super dangerous projects,such as high formwork,cantilever steel platform,deep foundation pit and attached scaffold,are selected as the research objects.In the high formwork section.Four factors affecting the high formwork support system,including material defects,design scheme defects,structural defects,construction management and process monitoring defects,are analyzed.The influence of structural factors on the stability of the frame is analyzed by using SAP2000 finite element software.The results show that the sweeper is more important to enhance the bearing capacity of the frame,and the higher the sweeper is set,the lower the bearing capacity is;the horizontal bar cannot The larger the step distance is,the lower the stability bearing capacity is;the lower the horizontal cross bracing density is,the lower the bearing capacity is;the lower the vertical cross bracing density is,the lower the bearing capacity is;the larger the length of the vertical pole extending out of the top layer,the lower the bearing capacity;and the larger the distance between the poles,the lower the bearing capacity.At the same time,according to the stress analysis of different pouring methods,it is shown that the high formwork system also adopts the stacking pouring method.In the aspect of accident analysis of cantilever steel platform,this study analyzes the structural characteristics and accident causes of the steel platform,and sums up three risk points,including the quality risk of embedded parts and installation quality,the risk of hoisting hook and hook,and the risk of inadequate inspection.Using ANSYS finite element software to simulate the stress distribution of each part of the cantilever unloading platform under the actual construction conditions,the conclusion is drawn:in the construction process,the concentrated load should be avoided,at the same time,the safety factor should be increased in the simplified calculation to make up for the deficiency of the simplified calculation of the node;in the actual installation,the wire rope should be pretensioned in advance,or the end of the unloading platform should be raised by 10～30mm,It can improve the safety performance of steel platform.Deep foundation pit.This paper introduces the common foundation pit support forms in Yangzhou area,and makes a simple summary and Analysis on the possible causes of foundation pit safety accidents.Using PLAXIS 2D finite element software,this paper analyzes the internal force and deformation law of foundation pit supporting structure under the condition of over excavation,and the influence of over excavation on the stability of foundation pit.It is concluded that over excavation has great influence on the stability of retaining structure,and obvious deformation will occur,which is not conducive to the control of foundation pit deformation.Attached scaffold part.This paper analyzes the structural characteristics of the scaffold body,emphasizes the three special parts of the construction elevator position,the lifting material platform position and the scaffold stair position,and the scaffold body treatment measures for two parts of temporary tie and anti-dumping and anti falling.From six aspects of human,machine,material,method,environment and measurement,the safety prevention measures and safety supervision and management suggestions of attached scaffold are summarized.Through the analysis of the characteristics of the super dangerous project,the paper puts forward the safety precautions,through the analysis of the accident cases,puts forward the improvement measures,and finally guides the safety supervision points,so as to provide technical reference and support for further guiding and standardizing the safety management of super dangerous projects,so as to play a certain role in improving the safety management level of construction construction in Yangzhou.