Test device and method for studying erosion damage under pipe bag dam joint breakage condition

Abstract

The invention discloses a test device and a test method for studying erosion damage under the condition that joints between bags of a pipe bag dam are broken. Water flow states such as stable unidirectional water flow, reciprocating water flow and wavy water flow are provided for a pipeline sandbox system through a water flow control system, the hydraulic boundary condition of a pipeline side wall breakage is simulated, and water flow related information and sand particle related information in a test process are acquired by an information acquisition system, so that the simulation of the erosion damage process generated under the conditions that the joint pipelines of the pipe bag dam are broken under the action of different water flows is completed. According to the test device and method provided by the invention, the rule of erosion damage under the condition that joints of the pipe bag dam are broken is revealed from the macroscopic aspect, the dynamic change characteristics of a sand body structure can be observed from the mesoscopic point of view, and an erosion damage mechanism under the condition that the joint pipelines of the pipe bag dam are broken is revealed and a distinguishing criterion and method of erosion damage are summarized by establishing a relation between water flow and macroscopic and mesoscopic variables of particles and phenomena so as to seek damage control measures.

Description

technical field [0001] The invention relates to a test device and test method for scouring damage of a pipe-bag dam under the condition of seam damage. The device is used to simulate the scouring damage of the tidal water flow and waves on the pipe-bag dam filled with sand passing through the seam between the bags. The process belongs to the field of hydraulic engineering physical model experiment. Background technique [0002] With the protective development of offshore and estuary areas, the embankment technology of filled pipe bag dams has been more and more widely used in estuary and coastal projects such as coastal reclamation and land reclamation, and estuary reservoirs for freshwater storage and salt avoidance. The typical construction method of pipe-bag dams for fresh storage reservoirs is to first fill the large geotechnical pipe bags on both sides underwater to form a cofferdam, and after the cofferdam elevation reaches above the water surface, sandy soil is filled...

AI Technical Summary

Problems solved by technology

Because most of the foreign sand pipe bags are made of high-strength sand fabrics, the pipe bags can be made very long, the pipe bags overlap less, and the scouring stability of the pipe bag dam joints is not outstanding, so no relevant research results have been published so far.

However, in my country, since the pipe bags mostly use low-strength split-filament woven geotextiles, limited by the strength of the material, the length of the pipe bags is generally short, the height is small, and the number of layers is large. There are many joints in the axial direction. The existence of these joints is likely to cause the loss of dam core fill. Aiming at this problem, the team of Professor Shu Yiming of Hohai University has done a preliminary research

However, during the construction process, due to mechanical damage and other reasons, it is easy to cause damage to the side wall of the joint pipe. If there is no protection during the construction period and the protection is not in place after the construction is completed, the water level inside and outside the pipe bag dam will fluctuate. Under the long-term action of the water pressure difference caused by the water pressure difference, the reciprocating water flow caused by the tidal phenomenon, and the fluctuating water flow formed by the wave, the sand filling at the damaged side wall of the joint pipeline also has the risk of being washed away by the water flow, which brings greater safety to the dam body. Hidden dangers

At present, there is no research on the erosion damage of the side wall of the pipe-bag dam joint under the action of unidirectional water flow, reciprocating water flow and wave action.

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