The Settlement Analysis And Grouting Reinforcement Of Existing Buildings In A Residential Area

A residential area in Tianyuan District of Zhuzhou City is a brick-concrete structure house built on a 10 m deep backfill foundation,and its foundation is the end-bearing pile.After the completion of the project in 2009,there were several different levels of main structure cracking and foundation settlement accidents in 5 to 11 buildings in 2016.Among them,5 and 6 buildings were the most serious,causing inconvenience to residents' lives.Property security is also not guaranteed.After the relevant units tested,the preliminary identification conclusion was that the foundation settlement caused the cracking of the superstructure.Based on the research and analysis of engineering materials and domestic and foreign literatures,this paper combines the field engineering accident damage characteristics and numerical simulation methods to determine the reinforcement method of damaged buildings and provides reinforcement design and construction drawings.Settlement observations during construction during key points on the building.Through the whole process of the whole foundation reinforcement project and the comparative analysis of the settlement data of key working conditions,the main work and conclusions are as follows:1.The numerical simulation analysis of the engineering accident was carried out on the west side of the fifth building with the most serious foundation settlement.The influence of different combinations of the two conditions of the pile bottom sandstone and the negative skin friction on the settlement of the pile foundation was considered.The conclusion is that the maximum settlement is located at 46# pile,and the cumulative settlement value is 2.48 mm when considering thenegative skin friction,which is 0.04 mm and 1.61% increase compared with the negative skin friction.2.For the numerical simulation stage of foundation foundation reinforcement,the working condition is that only the pile bottom is reinforced and the pile side is not reinforced,the cumulative settlement of 46# pile is 2.54mm;compared with the working condition,the second pile bottom and the pile side are grouted and strengthened.The cumulative settlement of 46# pile increased by 2.36%.3.Through engineering data analysis and on-site reconnaissance,the main reasons for the most serious accidents in the 5th and 6th west sides of the resettlement community are:(1)The two foundations of the building are the thickest and contain weak interlayers(original ponds).(2)There are natural mixed soil slopes about 9m high on the west side of the two sides;(3)due to the failure of the ground drainage facilities,the underwater seepage of the surface will take away the foundation soil and cause the foundation beam to be removed from the bottom of the beam.Empty and deformed,the foundation is consolidated and the negative friction is generated at the periphery of the pile to cause the pile to sink.According to these reasons and numerical simulation analysis,the foundation grouting reinforcement scheme is determined.4.An on-site monitoring plan for the foundation-reinforced building in the community was developed.The settlement monitoring started from the time of grouting after the accident occurred.In the monitoring,the 46# pile is the pile with the largest cumulative settlement,the settlement value is 2.36 mm,and the simulated cumulative settlement error in the second point is within 5%.