For jiangpinghe double - curved arch dam , 3 - d elasto - plastic fem is made , in which the point safety factors of the dam - abutments system and the safety margin for coefficients of sliding resistance on 7 potential sliding blocks of the dam before and after the reinforcement of the dam are calculated under the conditions of the normal storage level and the design flood level respectively based on the results from the analysis made with fem 摘要对江坪河双曲拱坝进行了三维弹塑性有限元分析，利用有限元应力成果分别计算了正常蓄水位、设计洪水位等3种工况下加固前后坝体坝肩系统的点安全系数和7个可能滑动块体的抗滑富余系数。
According to the instance of the arch dam built , take the discount quotiety , the verification flood water level , the frictional quotiety and , the agglomerate force and as stochastic variable quotiety , calculate the reliability index of the abutment with the calculational programme after the average value and variable quotiety is known 对于所取的拱坝实例，以扬压力折减系数，校核洪水位，摩擦系数、 ，凝聚力、为随机变量，在已知其均值并设定变异系数的前提下，利用电算程序计算其坝肩岩体的可靠指标。
The results indicated that with the change of water and sand condition and the altitude of tongguan and the development of the industry and agriculture in recent decades , the water environment of wei river had changed largely , which were shown as follow : annual runoff and seasonal flood decreased sharply ; water stream of large discharge decreased and the range of runoff decreased greatly ; sediment load per year decreased generally , sediment concentration of water increased , and the sand silting up was serious ; water channel swung and shrank , and water regime deteriorated ; frequencies of big floods decreased obviously , and hyper concentrated flood increased obviously ; water levels of the same runoff rose universally , and the frequencies of the floods increased and aggravated ; water pollution was very serious 结果表明，近期随着水沙条件、潼关高程等的变化及工农业的发展，渭河的水环境发生了巨大变化，表现在年水量及汛期水量锐减；大流量级水流出现次数减少，水量减少幅度大；年输沙量总体减少，河水含沙量增大，泥沙淤积严重；河道向摆动型发展，河道萎缩，河势恶化；大洪水发生的次数显著减少，高含沙小洪水明显增多；同流量洪水位普遍抬高，洪灾发生次数增加，洪灾加重；水质污染极为严重。
So this article analyses deeply in the method of ensur ' my designing food rolume which is an important element to affect the " designimy height of bridge " it brings forward an " arverage optiminmy suiting line " method which is a bondage discommode series at the same time it puts forward a ensurmy principle for rough coefficient " and " fallimy flood proportion which are both suitable to heilongjiang province at last this article introduces the " three - days rainimy rolume " method 本文立足于黑龙江省各种河流的洪水特点，结合以往工程实际，对影响跨河桥梁设计高度的主要因素? ?设计洪水流量及其相应洪水位的确定方法加以详细分析。提出有约束不连序系列的加权优化适线法及适合于黑龙江省的河流粗糙系数和洪水比降的确定原则，并介绍了三日降雨量法。
Finally , by using of the mathematical model , it is calculated and predicted the effect of the different tongguan riverbed elevations as well as the different conditions of incoming water and sediment on the variance of the flood elevation and the tend of aggradation and degradation of the lower weihe river bed . it is answered quantitively the lessening extent of sediment silt and the decreasing extent of the flood elevation of the lower weihe river after 14 years on two different incoming water and sediment conditions with three different tongguan elevations , respectively 328m , 327m and 326m . these results supply important references to the planning of flood control and comprehensive regulations of the weihe river basin 最后用验证后的数学模型对不同水沙系列、不同潼关高程( 328m 、 327m 、 326m )下渭河下游的冲淤趋势和洪水位的变化进行了预测计算，从定量上回答了潼关高程从328m降至327m (相当于潼关高程降1m )和潼关高程从328m降至326m (相当于潼关高程降2m )时，渭河下游14年之后各河段的减淤程度以及不同流量级洪水位的降低幅度，这些成果对于渭河下游防洪治理规划的制定具有重要的参考价值。
At first , this paper analyzes the factors of water - sand influencing water level of yellow river and the feasibility just using the factors of water - sand to study water level , and collects the corresponding data ; secondly , because there are strong nonlinear relation in the corresponding data , by meticulous theory analysis , this paper integrates basic nonlinear analysis method , theory of random analysis , method of least squares and so on . it puts forward a method which can get the high accuracy simulation of the data , perfects the multi - factor analysis of variable ( over three factors ) of the statistic ; thirdly , it applies the method to the approximation of corresponding water level process which belong to the capacity of sand of middle - high and middle - low , and get the high - accuracy simulation about the typical nonlinear relation ; at last , this paper definitudes the main influence mode that the capacity of sand . it mainly unite with other factors to work on the water level in the yellow river lower reaches ; mor eover , this paper analyzes the difficult point and the direction of improvement to realize the accuracy forecasting of the flood level of erodible - bed channel 首先，系统分析了影响黄河水位的水沙因素，及仅用水沙因素有效研究水位的可行性，并按变量对应思想采集它们的相应数据；其次，由于相应水位过程数据中含极强的非线性关系，本论文经细致的理论分析，将基本的非线性分析方法、统计建模方法、随机分析理论、最小均方误差原则等等数学理论及方法有机揉合，提出了能有效实现这类数据高精度拟合的分层筛选法，并改进了统计学中多因子(三个以上)方差分析法；再次，将这一方法用于黄河中高及中低含沙类洪水相应水位过程的拟合，实现了这一典型非线性关系的高精度拟合，各年汛期上下游相应洪水位过程的拟合误差都较小；最后，明确黄河下游含沙量对水位的主要影响方式，即含沙量主要是与其它因素联合对水位作用；另外分析了要实现变动河床洪水位过程准确预报的困难所在及改进方向。
