Large Scale Model Test And Underwater Installation For The Expansive Stressed Grouted Clamp

Expansive stressed grouted clamp as an effective maintenance technology improves the installation efficiency of the traditional self-stressed grouted clamp. As a kind of economical and efficient reinforcement technique for underwater damage component, it gets rid of the process of renting an engineering ship for a second time to tension clamp bolts. In order to promote the engineering application of expansive stressed grouted clamp, the capacity performance of a large scale clamp model has been tested and analyzed. In addition an auxiliary system has been developed for underwater installation as well in this paper.First of all, the distribution of expansive pressure at the inner surface of grout annulus is analyzed by multipoint strain measurement on the surface of inner tube. At the same time the average expansive pressure at grout outside surface is analyzed through the bolt tensile force measurement. Finally the push-out method is employed to test the slip capacity of clamp, combined the analyses by the distribution of expansive. pressure as well. Experimental results show that the distribution of expansive pressure at the inner surface of grout annulus in each section of the tube is the same, but uneven at different position of the same section. Because there is a gap existing at the top of the grout annulus, the expansive pressure is the largest at the bottom, smaller at side position and even negative pressure at the top position. From the average expansive pressure on the inner surface of grout annulus, which is deduced theoretically from the outside surface average expansive pressure tested by bolt tensile force, we could find out that the bottom expansive pressure on the inner surface from measurement is close to the average expansive pressure value deduced, however the side expansive pressure is smaller than the average. Furthermore through slip capacity test the stain changes on the tube surface are also found to confirm the conclusion of uneven distribution of expansive pressure. At last, this type of clamp could form the slip capacity at very short time (about 3 to 4 days).Secondly, a set of underwater installation auxiliary system for short-bolts expansive stressed grouted clamp is developed. At the same time, the design method of this installation auxiliary system is summarized. The appropriate open angle of the double saddle plates for installation is analyzed, and an experience formula of the open angle is summarized. The formula can be used to calculate the appropriate open angle which is depend on the tube diameter and the size of saddle plate as well. The open angle is proportional to the former and is inversely proportional to latter. In addition, this formula can be used in solving directly with fully considered negative effect by size error and redundancy. Plate lifting point location selection and the rocker arm open angle problem has been analyzed. The lifting point location is decided by the open angle of the double saddle plates, and the rocker design is determined by lifting point location and open angle both. So the logical sequence of design is critical. The location of lifting point is selected by the relative position between center of mass of one saddle plate and the lifting point to form a reasonable resultant force from during closing process of saddle plates. The rocker arm is designed considering the structure redundancy of the installation process and saving material etc. In the final, problem of the clamp positioning is summarized and analyzed as well as the key dimensions and their relationship for the design. The development of auxiliary installation structure provides the necessary technical support and preparation for the underwater installation application for clamp in the future.The capacity performance of a large scale clamp model is tested and analyzed by multi-point strain measurement firstly. The distribution of expansive pressure at the different section of grout annulus is tested as well as the slip capacity. The average expansive pressure at grout outside surface is analyzed through the bolt tensile force measurement. Furthermore the expansive pressures are verified by the theoretical value. The distribution of expansive pressure of large scale clamp model is tested as well as its process of establishing, which can provide valuable test data for the clamp engineering application. Secondly, an underwater installation auxiliary structure is also introduced. This auxiliary structure not only has simple structure which is conducive to recycling and also make fully used of gravity to fold saddle plates, thus eliminating the hydraulic power assist device, greatly save the maintenance cost. The design ideas and methods summarized in this paper can provide effective technical reference for the engineering application in the future.