Design & Practice Of The Reverse Construction Method

The buildings in the city are becoming more and more congested with thedevelopment of city at very fast speed. During the rebuilding of the old city, more andmore high buildings are located in close-packed district. The construction fields arevery narrow, with little space left for designing and construction. During theexcavation of foundation ditch, we must take the effect of the surroundingconstructions as important factor. The Reverse Construction Method developed inrecent years, is becoming an available technical method to resolve these kinds ofproblem.The Reverse Construction Method is named by its subsequence of constructingwhich is different from the routine. The technical principles of this method are: Firstlocated the middle pile and pole at the correct place along axial line of basement orunderground diaphragm or other supporting construct. And then build the beam andslab construction for supporting diaphragm. At last excavate soil and buildunderground construction step by step until under board reach the base coat. At thesame time we can build the upground construction because we have finished the firstfloor. With this way we can do the underground and over ground work at the sametime till the building is finished.The Reverse Construction Method has not been well developed in our country.The paper discussed the designing method of the Reverse Construction Method andmade a comparison with the regular construction method and studied some keytechnique of the Reverse construction procedure combining construction practice,such as diaphragm and mid-maintain columniation designing and constructing,dewatering, earthwork excavating, diaphragm wall structure constructing, surroundingbuildings protection, construction inspecting and so on.The Reverse Construction Method is not only a construction technique, it requiresthe integration of structure designing and construction designing. Some keytechniques are involved through this study.The first study is about load-bearing system. It is composed of diaphragm walland supporting pole. They are not only supporting system but also a part ofunderground construction. So the Reverse Construction Method is the designing ofexecution and construction, these two facts must be combined very closely.Diaphragm wall have three effects in the Reverse Construction Method, it cancountercheck soil, compose the construction and countercheck water. The paper studythe diaphragm from layout way, principle of design and computation, internal force inthe diaphragm, vertical load-bearing force, computation of the inserting depth into soiland the design of the joint of diaphragm wall.By adopting the Lizheng software as the tool for design and calculation inWangfujing engineering project, and combining the in-situ monitor technique, thesuccessful guidance is achieved for the Reverse Construction Method. In the ReverseConstruction Method, the vertical plinth is used for both temporary support andstructure pole of the basement. In this paper, the design and calculation principle, thedesign of vertical plinth and the orientation method are studied. In the Wangfujingengineering project, the upright adjustment device is developed to solve the keytechnology problem of the upright adjusting of the pillar. In addition, combined withthe demand of the Reverse Construction Method, the differential settlement of verticalsupporting system and the construction method of joint are studied.Because the Reversing Process is carried out in a comparatively closed system,the special demand for dewatering engineering and earthwork engineering is needed.Aiming at the characteristics of the Wangfujing mansion engineering, the dewateringmethod by self-infiltration well is put forward. And this method effectively resolve theproblem of the disturbance among the dewatering engineering, earth engineering andstructure engineering encountered in the Reversing Process. In the earthworkengineering, the construction is difficult and the progress is slow due to theconstruction is carried out in a closed environment. The design idea of wholly reverseand partial ordinal are put forward in the thesis, which not only reduce theconstruction difficulty but speed the rate of progress. Also, the rational excavationsequence of the earthwork is designed, which decrease the turbulence of earthworkexcavation to the lateral displacement of the diaphragm.In the Reversing Process, the construction of underground structure is closelyrelated with the surrounding structure. In this thesis, the later perfusion process is putforward aiming at the steel pillar in Wangfujiing mansion engineering. At the sametime, the construction method of large volume concrete, the crack mechanism and theinfluence factors are studied.One of the advantages of the Reverse Construction Method is that it can protectthe surrounding buildings. The diaphragm and the upper floor planks became a systemwith high rigidity, which effectively control the lateral displacement of the diaphragm.In Wangfujing mansion engineering, the distance between the outer shell of thediaphragm and the independent foundation is only 85 mm, while the height differencebetween them is 21 m. Based on this situation, the Reversing Process combined withthe reinforcing method with closely arranged pile is put forward in this thesis, whicheffectively guarantee the safety and normal use of the surrounding buildings.Information-based construction insures the success of the Reverse ConstructionMethod. The construction monitor design is the important part of the design of theReversing Process. In this thesis, the practical monitor data are analyzed andprocessed and compared with calculation value. In one hand, this verifies the accuracyof the calculation done in this thesis, on the other hand, this provides the reference tothe design of the Reversing Process for the future.In the last part of this thesis, the underground temporary lighting and wellventilation problems are put forward, which are the assurance of the success of theReverse Construction Method. The thesis analyzed the underground temporarylighting and well ventilation systems of the mansion engineering of Wangfujing inorder for the reference to the design of the Reverse construction method for the future.This paper based on WANGFUJING mansion project, which uses reversingprocess method in the whole work, in the same time, the theory of reversing processmethod is improved in practice. And we get some achievements in this paper, such as:Crossed steel plate junction is taken into consideration for the first time in thedesign of the diaphragm junction. It is proved to be success for its water resistingcapability and bearing capability, also it simplifies the construction process.Auto-oozed lowing water method is used successfully in the reverse constructionprocedure, which effectively reduce the cross work. And it provides a new method forthe construction.Using steel columniation in the location work, we solved the problem ofdeviation control. And the use of this method is a great breakthrough in theconstruction process.Side-deviation is effectively controlled by the application of the ReverseConstruction Method. And the largest deviation is controlled below 20 mm.By selecting the best bearing layer, we reduced the settlement value to 15 mmbetween concrete wall and the middle columniation, and it accumulates goodexperience for the similar project.Order-method and reversing method come into together in the earthwork, and itimproves both of two methods in the progress.Wasting of money is avoided in the reverse construction method, at the same time,it improves the speed of the construction process. Therefore, it reduces the cost by 14percent, and it deduces the time limit of the project by 20 percent.In the Beijing WANGFUJING mansion project, the reverse construction methodgets the most effective economic efficiency and social benefits. And it provides a goodexample for the similar work. Besides, it improves this technology at the same time.All in all, this technology will play an important role in the subway and under-groundconstruction in the city of China.