加筋无黏性土石坝漫顶溃坝试验研究

研制了封闭式循环供水土石坝溃坝模型试验装置,并应用该装置开展了室内模型试验,对加筋无黏性均质土坝的溃坝过程进行了系统研究,探讨了坝体加筋对溃坝流量过程线的影响规律。研究结果表明:在水泵出水口设置消能弯管和挡水隔板可保证模型上游供水的稳定性,在试验装置侧面设置连接上下游的U型测流弯管,把明渠流转化为满管管流,在U型弯管下侧平直段安装电磁式流量计量测溃口流量,可有效提高流量过程线的测量精度;加筋无黏性均质土坝的漫顶溃坝过程可分为坝体下游未加筋区域、加筋嵌固区和上游未加筋区域破坏3个阶段;随着加筋体埋深的增加,峰值流量呈现先增大、后减小,再增大的变化规律,在坝高的35%~50%范围内埋设加筋体,能够降低溃坝峰值流量;减小加筋体竖向间距能有效延滞溃坝峰现时间。

Experimental study on overtopping of geotextile-reinforced noncohesive embankments

A circulating water supply device was developed and thirteen small-scale embankments overtop-ping breach tests were conducted with the device. The breaching process of geotextile-reinforced noncohe-sive embankments was studied and the influence of dam geotextile reinforcement on flow process line of dam break was discussed. Conclusions can be drawn that:Using a folded energy dissipation pipe installed following the valve can guarantee the stability of upstream discharge,and using a U-bend pipe with flowme-ter installed laterally connecting the circulating flow can effectively improve the measurement accuracy of downstream discharge. The breaching process of the reinforced noncohesive embankment can be divided into three stages:erosion of the downstream unreinforced part, erosion of the geotextile stiffened part and ero-sion of the upstream unreinforced part,respectively. An effective reinforcement zone to reduce the peak dis-charge is found at 35% to 50% of the dam height. A decrease in geotextile spacing can enhance the an-ti-erosion properties and delay the peak time.