Thirdly , because the depth of the seepage prevention wall of xia ban di dam project has the value of 85m which is the maximum depth in the dam projects in our country , the stress state of the seepage prevention wall is very complicated , the influence of nine modulus for nine kinds of seepage prevention wall material on the stress and displacement of the seepage prevention wall is studied and the rule of the change of stress and displacement with the change of characteristic parameters for seepage prevention wall under time of engineering completion and water impounding operation period is given in this paper 第三,鉴于大坝基础混凝土防渗墙深度达85m ,厚度仅为1 . 0m ,防渗规模和工程难度为国内之最,墙体应力比较复杂,本文研究了大坝施工填筑竣工期、水库蓄水运行期防渗墙的应力和变形随墙体参数的变化而变化的规律,为大坝安全设计及防渗墙墙体材料的选择提供了理论依据。
In the summer stratified water column , the deeper the maximum depth of food distribution is , the stronger the dvm is performed ; the increase of the gradient of temperature in the thermocline layer can decrease the magnitude of the dvm and form the thermal barricade to the copepod ; the effects of the predation pressure on dvm is complex . on the one hand , the variations in the distribution depth of the predation pressure vs . the thermocline layer or the depth of the maximum food can modify the dvm patterns of the copepod . on the other hand , different predation pressure induces different dvm patterns 在夏季分层水体中,食物的最大分布深度越大,动物向下迁移的幅度也越大;温跃层的温度梯度增大可以减小动物迁移的幅度,成为桡足类垂直迁移的温度屏障;捕食压力对垂直迁移的影响较复杂,一方面,捕食压力的分布深度与温跃层或食物峰值的相对位置的变化能够改变桡足类垂直迁移的模式,另一方面,捕食压力强度不同,桡足类垂直迁移的幅度也不同,捕食压力越大,迁移的幅度越大,当捕食压力增加到一定程度,桡足类停止向上的迁移,大部分时间呆在水体深层,可能进入捕食压力引起的“滞育”状态。