河道采沙对大桥基础安全影响研究

近年来河道大量无序采沙对大桥安全带来丫隐患。由于采沙破坏了天然河床的平衡状态，可引起长距离河床整体下切，对已有跨河桥梁工程不利。采沙坑距大桥较近时，在水流剪应力作用下沙坑演变可很快造成大桥基础变浅，影响大桥的正常安全运用。本文分析了采沙位置和采沙坑深度对桥墩基础安全的影响，根据采沙坑演变的平衡比降，认为采沙坑距大桥的安全距离主要与河床粒径及水流流速有关。

Study on the effect of sandpits at riverbed on bridge foundation safety

In recent years, sand excavation optionally at river hed has brought trouble to some bridges. Because it destroyed the river equilibrium, sand excavation would cause river bed erosion in large scale, which is danger our to the structure across the river. If sandpits are near bridge location, its evolution when subject to suitable shear stress of the flow will rapidly cause the bridge foundation instability. In this paper, the impact of the sandpits location and its depth to the bridge foundation stability are studied. According as the equilibrium gradient of the river hed with sandpits, the safety space between sandpit and bridge base are considered to he related mainly with sediment diameter of the river bed and velocity of the water flow.