城市桥涵工程（Urban bridge and culvert engineering）.doc

城市桥涵工程（Urban bridge and culvert engineering） 2K31200 City Bridge Engineering City Bridge Engineering Foundation Pit mainly for pile caps, abutment and expansion of infrastructure construction, generally divided into support and support two. No, a pit (a) without supporting conditions: 1. pit depth of foundation is not deep, the construction period is short, digging pit does not affect the safety of the building near the 2. underground water level is lower than the substrate, or infiltration of small, does not affect the stability of pit wall (two) no pit wall form of foundation pit: pit wall form of foundation pit is divided into vertical wall pit, slope and ladder shaped pit wall and pit wall slope. For the natural humidity near the optimum water content, structure uniform, without sliding, moving, loose or uneven foundation subsidence, foundation pit depth is less than 1~2m may adopt vertical pit wall form. Through the different layers of foundation pit, the pit wall slope according to each layer of soil with different slopes in the pit wall slope transformation at the visual need at least 0.5m wide platform. (three) no foundation pit construction note: 1. excavation should be preceded by good drainage, in the foundation around the top edge to the peripheral drainage slope, and drainage ditches in the appropriate distance, and should prevent water seepage, so as not to affect the stability of pit wall. The excavation, should be timely to drain the water in the pit. 2. pit edge should be a berm, away from the pit is not less than 1.0m; the supporting vertical pit wall pit also should be widened, stacked soil height shall not exceed 1.5m. 3, when construction should observe the pit top floor cracks, the pit wall has no loose collapse phenomenon, ensure the safety of construction. 4, the construction of foundation pit can not continue for too long, since the completion of excavation to the foundation, should seize the time, continuous construction. 5. mechanical exca