在南水北调中线永定河倒虹吸工程穿越大宁库区的4孔过水方涵基础施工中,遇到了土层地质不良问题。主要存在的地质问题是:由于大宁水库前些年开采砂石料,部分地段的方箱涵基础坐落于杂填土及淤泥土上,经勘测,厚度5 m左右,不能满足设计承载 During the construction of the 4-hole cross-culvert aqueduct across the Daning reservoir area, the Yongdinghe inverted siphon project in the mid-route of the South-to-North Water Diversion Project encountered poor geological conditions of the soil layer. The main geological problems are as follows: Since the Daning reservoir was used for excavation of gravel materials in previous years, the square box culvert foundation of some sections was located on miscellaneous fillings and silt soils that the surveyed thickness of about 5 m did not meet the designed load