Model Tests On Capacity Properties Of Expansive Stressed Grouted Clamp

Grouted clamp is a common selection in the repairing and strengthening technologies for offshore structures. The stressed grouted clamp, which has been widely used in abroad with the advantages of a high tolerance of imperfection and good fatigue properties, is the most common repair method when the structural components are damaged underwater. But this type of clamp has the drawbacks of complicated underwater operations and high related cost. So this paper introduces an expansive stressed grouted clamp whose cement slurry is mixed with expansive agent accordance with the existing problems of stressed grouted clamp. And the following research works are carried out:Firstly, the use of expansive stressed grouted clamp is introduced. According to the drawbacks of complicated underwater operations and high related cost of the traditional stressed grouted clamp, the use of expansive stressed grouted clamp is introduced. This new type of clamp, whose cement slurry is mixed with suitable amounts of high efficient expansive agent, utilize the expansion deformation during the cement setting to induce radial self-stress at the grout/steel interface. Due to the improvement of construction efficiency and reduction of cost, the expansive stressed grouted clamp has higher engineering value.Secondly, a method for directly measuring the local expansive pressure of expansive stressed grouted clamp is proposed. Considering the various factors that affect the expansive pressure measurement comprehensively, a method for directly measuring the strain of damaged inner tube is proposed and the expansive pressure induced by grout annulus is then obtained. This method can provide experimental basis for the study of self-stress distribution of the clamp grout.Thirdly, the empirical formula for relationship between expansive pressure and slip stress that suitable for FEA expansive agent is proposed. The empirical formula based on the experimental data and two existing empirical formulas fits the experimental curve very well. In the empirical formula a factor of expansive pressure augmentation is introduced to compensate the increase of slip stress induced by expansive pressure.Fourthly, the factors affecting capacity properties of expansive stressed grouted clamp are studied. Researches on the factors that affect the capacity properties of clamp, such as different type and different content of expansive agent and super-plasticizer, are carried out. The type of expansive agent suitable for expansive stressed grouted clamp is found out. The mechanism that the super-plasticizer affects the capacity property of clamp is also preliminarily analyzed.The model tests of expansive stressed grouted clamp indicate that high expansive pressure can be rapidly obtained after grouting and the largest slip capacity of 2.5 MPa can obtained. So this type of clamp can meet most repairing and strengthening demand of underwater components and is suitable for the repairing and strengthening of offshore structures.