黄河标准化堤防工程淤背的合理设计宽度

Reasonable design width of the back of silt area in the standardization dike project of Yellow River

黄河下游标准化堤防建设中,采用放淤固堤方式提高堤防的防洪能力.由于黄河堤防的水文地质条件极为复杂;有的大堤常年甚至多年不靠水,难以通过原型观测资料率定土层的渗透系数,常规的渗流分析方法难以确定大堤淤背的设计宽度.可靠度理论将影响工程安全的因素视为随机变量,通过建立功能函数来求解失效概率或可靠度,据此评价工程的安全性.在考虑黄河堤防土体参数随机变异性的基础上,编制渗流可靠度程序,分析设计洪水位下,黄河堤防背河坡脚不同距离地层土体的渗透破坏概率,从而确定淤背的合理设计宽度.实例分析表明,该法计算结果与其它研究成果一致,可为黄河堤防放淤固堤工程设计提供理论依据,并可供其它河流治理时参考.

In the course of building the standardization dike in lower Yellow River, the capability of controlling flood was improved by reinforcing dike with silt. Because of the extra complexity of hydrogeological conditions of dike in Yellow River, it is difficult to obtain infiltration coefficients of soil layers by antitype observation data so that the design width of the silt area difficulties hard to be determined by routine methods of seepage analysis. The influencing factors of project safety are treated as stochastic variables in reliability theory, and disabled probability or reliability can be solved by establishing function so that the project security character can be estimated. Based on stochastic variability of soil parameters of dike considered in Yellow River, the program of seepage reliability is worked out. With the program, the probability of infiltration destroy of stratum soil is analyzed in different distances of slope feet in back - river of dike in Yellow River under the floodwater level of design so that the reasonable design width of the silt area can be confirmed. Analysis of an example shows that the results of the method is consistent with other research results, thus the study can provide a theoretical basis for project design of reinforcing dike with silt in Yellow River.