Artificial-Crack-Behavior Test Evaluation of the Water-Leakage Repair Materials Used for the Repair of Water-Leakage Cracks in Concrete Structures
There are no existing standard test methods at home and abroad that can verify the performance of water leakage repair materials, and it is thus very difficult to perform quality control checks in the field of water leakage repair. This study determined that the key factors that have the greatest impact on the water leakage repair materials are the micro-behaviors of cracks, and proposed an artificial-crack-behavior test method for the performance verification of the repair materials. The performance of the 15 kinds of repair materials that are currently being used in the field of water leakage repair was evaluated by applying the proposed test method. The main aim of such a test method is to determine if there is water leakage by injecting water leakage repair materials into a crack behavior test specimen with an artificial 5-mm crack width, applying a 2.5 mm vertical behavior load at 100 cycles, and applying 0.3 N/mm2 constant water pressure. The test results showed that of the 15 kinds of repair materials, only two effectively sealed the crack and thus stopped the water leakage. The findings of this study confirmed the effectiveness of the proposed artificial-crack-behavior test method and suggest that it can be used as a performance verification method for checking the responsiveness of the repair materials being used in the field of water leakage repair to the repetitive water leakage behaviors that occur in concrete structures. The study findings further suggest that the use of the proposed test method makes it possible to quantify the water leakage repair quality control in the field.
Analysis of dynamic behavior for underground structures under earthquake loading
Abstract The behavior characteristics of underground structures are reported as they are not affected by their dynamiccharacteristics such as surface structures, but by dynamic characteristics of soil and rock surrounding the undergroundstructures. Therefore, dynamic behavior of surrounding soil and rock dominates the dynamic behavior of the undergroundstructure. The purpose of this paper is to analyze the dynamic response (longitudinal deformation and ovalingdeformation) of the underground structure under earthquake loading. The dynamic responses of the underground structureswere evaluated with varying earthquake conditions, soil conditions, and structural conditions using conventionalclosed-form solution of seismic behavior of underground structure. In addition, shaking table tests were conducted tosimulate the earthquake loading and the dynamic behavior of the model was analyzed . Keywords: Underground structure, earthquake, longitudinal deformation, ovaling deformation, shaking table test요지지진시지하구조물의거동은구조물자체의동적특성보다는주변지반의동적특성에영향을받는다따라서.구조물을감싸고있는지반의특성이구조물의동적거동특성을좌우한다본연구의목적은지진시지하구조물의동적.거동및응답특성축방향변형및 변형을분석하는것이다지진시지하구조물의동적거동및응답특성을분석하기( ovaling ) .위해서지반조건지진조건구조물조건변화에따라구조물에발생하는응답을이론해법을이용하여분석하였다추가적으,, .로소규모의모형실험체를이용한진동대실험을수행하여구조물의동적거동을분석하였으며이론해를이용한해석결과,와비교분석한결과경향성이잘일치함을확인할수있었다 .주요어
Turbulent boundary layer wall‐pressure fluctuations downstream from an abrupt change in surface roughness
Spectra of wall‐pressure fluctuations beneath a turbulent boundary layer have been investigated immediately downstream from an abrupt change in surface roughness, from slightly rough to very rough. Over the measurable frequency band (400 Hz to 7 kHz), the spectra in the first 150 mm scale on wall variables. This indicates that the motions responsible for the pressure fluctuations measured in this region are very close to the wall. Farther downstream this scaling procedure breaks down. It is suggested that the initially thin internal layer behaves independently of the flow external to it until it has grown appreciably and only then interacts with the outer boundary layer. It was found that, for all frequencies measured, the dimensional spectral level decreases initially then rises to a maximum at 250 mm from the roughness change before decreasing once more. The position of the maximum is close to where the internal layer ceases to have a distinct edge.