Analysis On Impact Of Surroundings Around Excavation By Covered-down Technique

It is no doubt that urban space is becoming more and more crowded by the highspeed of urbanization development in China, and developing urban underground spacerepresent a general trend. It must be confronted that more complicated surroundingsaround excavation by under ground construction in urban center region, and the morestrict requirements for protecting foundation pit structure and surroundings aroundexcavation are brought up. Thus, the Covered-down Excavation method has beenwidely used in urban underground construction, which has the advantage ofshortening the interruption of ground transportation and reducing the influence offoundation pit excavation on the surroundings, and it has been the first choice ofexcavation in construction project in urban underground engineering. However, as theparticularity of its excavation method, the relationships of the retaining structuredeformation, peripheral surface displacement and the impact of buildings neigh byhave become more complex.Based on one civil air defense engineering in Xiangtan, the monitoring offoundation pit had been taken action in the section of Station Road, which had usedthe Covered-down Excavation method in the first-stage project. With the practicalparameters of the engineering, the computational model had been installed by theexcavation environmental impact analysis software (JK3E), and the comparisonbetween numerical simulation results and practical monitoring results had beenanalyzed, the impact pattern of surroundings around excavation by Covered-downExcavation method had been figured out as well, the analysis results could bereferenced in follow-up construction or in other similar projects. The main researchcontents and conclusions in this paper are listed as follow:1. The excavation monitoring program of Station Road section had been designed,the settlements and horizontal displacements of buildings and roads aroundexcavation had been tested respectively, and the transformation rule during excavationhad been summarized on the basis of practical monitoring data. The results showedthat it is very effective to reduce the impact of surroundings around excavation byCovered-down Excavation method, which had been compared with traditionalmethod.2. Based on the actual parameters of construction engineering, the computationalmodel had been installed by the excavation environmental impact analysis software (JK3E), the results which including lateral displacement of the retaining structure,settlement of surrounding ground surface and deformation of buildings neigh by, wereall figured out in the calculation models. According to the practical problems inmonitoring project, the monitoring program had been optimized and improved bycomparing the results between calculations and monitoring data, and the insufficientor limitations in practical monitoring had also been repaired though the calculatedresults.3. The surface subsidence coefficient estimate experience and other relativeparameters had been put forward by correcting the computational parameters inanalysis models constantly. Based on the revised parameters, the impact rules ofsurroundings around excavation in different conditions had been researched, and theinfluence factors had been summarized at the same time. This all above researchresults could be referenced in follow-up construction or in other similar projects, aswell.