Study On Key Technology Of Super-sized Underground Diaphragm Wall Construction

As the scale of underground space development is bigger and bigger and foundation pit is deeper and deeper,big-size and super deep diaphram wall is used in undergroud project more and more widely. Taking the Municipal Utilities Costruction Project of YuJiaPu Comprehensive Traportation Hub as background,this paper mainly studies the constrution method of super-deep diaphram wall in very complicated geology condition with upper soft earth layers and under hard sand layers. A series of key problems are solved and a suit of systemic diaphram wall construction technology is formed gradually throughing studying diging of pit ,making of mud, lifting up and laying down of steelbar cage.Through analyzing accuracy control of digging diaphram wall pit and Prevention of concrete from flowing out and quality control of diaphram wall joint,conclusions are reached as follow:1.acquiring and selecting different digging method and paraneters in different geological condition trough trying digof diaphram wall pit.2.remforcing the upper mucky clay layer with mixe piles in order to making sure the stability of the clay layer during digging the diaphram wall pit.3. When digging in hard sand layers,guiding holes should be made before digging the wall pit, and slurry with bigger gravity should be used to maintain the stability of sand layers.4. The reinforcement cage of diaphram wall shuoud be lif up and put in wholly in one time in order to saving time, and hooking points of the cage should be designed correctly.Before formal lifting,trying lift should be done.The foundation pit of the Hub is 29.5m deep,and the diaphram walls as retaining structure of the pit is 61m deep. Problems involved are more complicated and study of this paper is more comprehensive and deep.Through fully researching this paper povides important technical parameters for super-deep diaphram construction in complicated geology condition in Tianjin Binhai New Area.