Research On Optimization Of Construction Scheme Of Underground Pit Yard Based On Modern Construction Technology

In recent years,a two-stage reduction target has been proposed in China,namely reaching the emission peak of carbon dioxide by 2030 and reaching the carbon neutrality by 2060.At present,carbon emission from the construction field is one of the main causes of air pollution.In traditional buildings,the underground pit yard has the characteristics of low energy consumption and no pollution,so it is a kind of green energy-saving building with great potential.With the improvement of people’s economic level and the development of science and technology,the advantages of underground pit yard construction,such as material-saving,warm in winter and cool in summer,have been gradually suppressed by the advantages of fast construction speed and convenient transportation of above-ground buildings.If you want to develop the pit yard,you must solve the problem of backward construction of the pit yard.In response to the above problems,this paper combines FLAC3 D simulation software to analyse the traditional construction process of the pit yard and carry out an optimisation study of it in terms of consideration of improving construction efficiency and construction stability.The main work is as follows:Firstly,the structural stability and force transmission mechanism of the patio yard and kiln were investigated by establishing a finite element model of the pit yard and simulating the displacement and stress fields of the patio yard and kiln in the pit yard during the traditional construction process.The specific work includes: monitoring the maximum unbalance force and the displacement change of the top of the patio yard during the construction process;simulating the construction process of two kilns on the earth wall of the pit yard and analysing the displacement and stress changes at the monitoring points.The results of the study show that the stability of the patio yard is high and the focus of construction optimisation can be on construction efficiency;the stability of the kiln is poor and the top and bottom of the kiln are deformation concentrated areas,so the focus of construction optimisation can be on construction quality.Secondly,in response to the inefficiency of the construction of the patio yard in the pit yard,a new type of excavation machinery and earth moving machinery suitable for the patio yard was designed and adapted to the construction plan.The work includes the design of a new type of earth-moving machine suitable for the pit yard,which can meet the earth-moving needs of the patio yard,and a new type of excavation machine suitable for the pit yard,which can meet the all-round excavation needs of the patio yard.Both machines are lightweight and easy to dismantle,and do not reduce the stability of the soil around the patio yard.This improves the efficiency of the construction of the patio yard and solves the problem of not having suitable machinery for the pit yard.Thirdly,in order to address the problem of poor construction quality,poor stability in the construction process,the paper introduces the half-hole method and the step method to the excavation of the kiln in the pit yard for optimal selection.The finite element models of the two construction methods were established and the stress and displacement fields of the two construction methods at different stages of construction were analysed.The results show that the half-hole method has better construction stability.The influence of the construction sequence of the half-hole method on the stability of the kiln was further investigated,and the optimal construction sequence was determined.Finally,simulations were carried out to verify the effect of the lining treatment of the kiln after construction.