移动式防洪系统力学性能及渗漏特性试验研究

移动式防洪系统是一种具备高安全性的标准化防洪方法,但在中国的城市防洪系统应用还不多,对其技术性能的研究不足是制约因素之一。该文依托某市的移动式防洪墙工程,设计移动式防洪墙综合试验基地,蓄水试验以及立柱加卸载试验,研究了移动式防洪系统的预埋件安装方法、受力性能和渗漏特性。结果表明,预埋件的直接安装法与预留槽孔法均能满足施工工艺和正常运行要求,但前者优于后者;蓄水后,移动式防洪墙存在渗漏现象,其与水位呈现指数的变化规律,当水位超过1.5 m时渗漏量会快速增大,达到1.7 m时渗漏量可达300 L/h;立柱加卸载(0~100 k N)过程中,首先会引起混凝土塑性变形,进而导致立柱产生残余位移,其受力过程表明立柱、预埋件与基座混凝土体系的破坏过程应是由预埋件两侧混凝土逐渐向迎水面发展。

Test on mechanical and leakage characteristics of mobile flood protection system

The high level urban flood control system is the basic guarantee for the sustainable development of modern cities, and the beautiful water environment and river landscape are the important symbols of modern cities. The need of protection is increasing with rising population density in low-lying coastal and river areas in the last decades. Therefore, the demand for technical protection measures is growing. It means that the construction of flood control projects should not only meet the requirements of urban construction, but also meet the requirements of water and shore two-way landscape viewing and residents' and tourists' visiting. Recently, more and more mobile protection schemes are on the market promising to fit both requirements: protection in case of flooding and open access to the floodplain in the remaining time. The protection systems differ in material, construction, height, and permanent facilities. They can be divided in structures made of sandbags, plates, concrete elements, flaps, trestles, geomembrane containers, and so on. However, the application of mobile flood control wall in China is not much, and the lack of research on its technical performance is one reason to the constraints. Based on the actual engineering project, the seepage characteristics of the mobile flood control system, and force condition on the foundation of column and embedded parts are studied through the experiment of water storage and column loading test. The testing results show that: Firstly, the direct installation method and the reserved slot method of the mobile flood control wall can meet the requirements of construction technology and normal operation. The anchor plate and foundation are not integrated when using the reserved slot method, which is just like the anchor plate and concrete integrated into the component to insert the foundation. The stress conditions of reserved slot method of anchor plate are worse than direct installation method. So we recommend the direct installation method in construction practice. But the 2 installation methods run safely, because the actual stress values under normal impoundment have only small change, far from steel yield strength (335 MPa) and concrete ultimate tensile strain (100×10-6). Secondly, a water storage pool was constructed to test the leakage characteristics. The mobile flood protection wall leaks when the pool is filled with water and the leakage changes exponentially with the water level. The regression analysis of measured water level and observation time is performed. The leakage will accelerate when the water level exceeds 1.5 m, reaching 300 L/h at a level of 1.7 m. It indicates that the leakage problem is an important aspect that the mobile flood control system needs to solve in order to increase the water retaining height. Finally, the loading and unloading testing of single post (this load limit is 100 kN) shows that when loaded to 25 kN, the concrete around the embedded part has plastic deformation. When the loading reaches 97 kN, the tensile deformation born by the concrete is close to the ultimate tensile deformation. And in the whole loading and unloading process, post and steel are in the elastic phase, that is, the measured residual displacement of the post and the residual stress of the steel are caused by the plastic deformation of the concrete. In addition, the stress analysis of the loading and unloading process shows that the damage of the post- anchor plate -foundation system will start from the concrete around the anchor plate and gradually develops toward the surface of the water surface until the whole is destroyed. Therefore, the mobile flood control system engineering should pay full attention to the construction quality of concrete around anchor plate.