非开挖穿河管道工程对堤基渗流稳定的影响评价

Seepage Stability Analysis on the Dyke Through by Trenchless Pipeline

非开挖穿河管道工程在河流与堤基下的地层中形成一条隐蔽、弯曲的扰动带,为了评价该扰动带诱发渗透破坏的可能性,结合工程实例建立了相应的地下水流数值模拟模型。利用该模型,在极端不利的水文、气象条件下,计算地下水流场中最大水力坡度;依据临界水力梯度法,定量评价工程诱发渗透破坏的可能性。实例研究表明,最大水力坡度值随河水位上升而逐渐增大,但增速逐渐变缓;河道底部厚度不大但渗透系数很小的淤泥层,对最大水力坡度值的影响十分明显。

A covert and curving zone,which is disturbed by trenchless pipeline engineering,is formed under the river and dyke stratum. Based on an actual engineering, a corresponding groundwater simulation model is proposed for evaluating the possibility of seepage failure induced by the disturbed zone Under the extremely unfavorable hydmlogy^weather conditions,the maximum groundwa- ter flow gradient is estimated by the simulation model. Then, the possibility of seepage failure induced by enginee^ng can be quantita- tively analyzed based on the critical hydraulic gradient method. The result shows that the maximum groundwater flow gradient is in- creasing gradually and its acceleration is decreasing corresponding to increasing river level. The maximum groundwater flow gradient is influenced obviously by the thin and low--permeability silt layer of river bed.