Abstract:The internal prestressed reinforcement is located in the interior of the prestressed concrete structure, and it is often difficult to inspect the hidden bend of the prestressed concrete structure no matter in the construction or service stage. Due to pipeline friction, anchorage retraction, instantaneous compression and long-term shrinkage and creep of concrete, and relaxation of prestressed tendons, the internal prestressed stress loss is inevitable. After the loss of prestress, it is very important to monitor the prestress and determine the permanent prestress. Magnetic flux sensor is made based on the principle of magnetoelastic effect of ferromagnetic materials. This measurement method directly monitors the state of components, which is a non-destructive and non-contact measurement method, and the sensor is easy to install and has good long-term stability. In this paper, the magnetic flux sensor is applied to the monitoring of internal prestressed tendons. The measurement principle, sensing performance, temperature compensation, relaxation and fatigue of prestressed tendons, test environment and engineering cases of the sensor are studied in detail. The research results show that the magnetic flux sensor is an effective method to monitor internal prestressed tendons.

Abstract:Taking the external prestressed reinforcement project of Yongjiang Bridge in Nanning City as the background, a detailed analysis of the anchoring structure anchored in the general beam section of the original structure was carried out by using the spatial finite element analysis method. According to the obtained spatial stress distribution characteristics, the structural measures for local reinforcement of the anchoring structure were considered The setting of channel steel and rebar can effectively reduce the stress concentration of the concrete at this position, make the stress distribution tend to be uniform, and the local stress can meet the requirements of the standard limit. At the same time, the engineering practice shows that the finite element detail analysis method is more in line with the actual stress characteristics of the anchoring structure, and the calculation results and local reinforcement measures can be used as an important reference for the design and construction of similar external prestressed reinforced bridge anchoring structure.

Abstract:In this paper, LS-DYNA finite element software is used to numerically simulate the performance of caverns reinforced with general anchorage structure and special composite anchorage structure respectively under explosion load. In this paper, the stress wave propagation and the formation process of explosion crater, the pressure wave in the surrounding rock near the explosion and the formation process of zone fracture of the composite anchorage structure are analyzed. The results show that the calculated crater sizes of the two models are in good agreement with the experimental results. The new composite anchorage section makes a local free surface appear in the weakened zone outside the anchorage zone, and the reflected tension wave produced by the explosion stress wave passing through the free surface leads to the fracture. The peak value of vertical vibration acceleration is 23.7% lower than that of single caverns. The single anchorage structure cavity is more prone to punching failure and tensile spalling failure than the composite anchorage structure cavity.

Abstract:In this paper, the limit analysis method is used to derive a trial formula for calculating the stability Angle of viscous slope. It is proposed that the stability analysis of the anchorage system should be carried out for the anchorage viscous soil slope.

Abstract:In the past, prestressed carbon fiber plate reinforcement bending tests were mostly based on the "first load" of the structure. In this paper, prestressed carbon fiber plate reinforcement "second load" of the reinforced concrete bending structure is studied experimentally from the actual situation that the structure is mostly "second load" in the reinforcement engineering. On the basis of the special anchorage for prestressed carbon fiber plate developed by Liuzhou Overwem Machinery Co., LTD., the author completed the model test of the flexural members of 2 test beams reinforced by prestressed carbon fiber plate and 1 test beam reinforced by non-prestressed carbon fiber plate. The mechanical properties of test beams reinforced by prestressed carbon fiber plates are studied. The effects of prestressed carbon fiber reinforcement on the bearing capacity, deformation, application efficiency and ductility of the specimens were studied. The test results show that the prestressed carbon fiber plate reinforcement can significantly increase the cracking and yield load of the flexural members, reduce the deformation of the members during the use stage, make full use of the properties of carbon fiber materials, and strengthen the design against the decreasing trend of ductility.

Abstract:Taking the stern section of the "Unblocked" ship sunk 12 nautical miles from Yantai Port in 2007 as an example, through in-depth analysis of the actual situation of the project, this paper describes the technical plan formulation, the tension jack system and the construction method of lifting and floating salvage by multiple tension jacks. This technology effectively solves the bottleneck of the construction of fast salvaging large-tonnage shipwrecks. It can also be used for river wreck salvage.

Abstract:Taking Minpu Bridge steel girder high-speed lifting as an example, this paper describes the design calculation, installation and construction technology of hydraulic lifting equipment, and introduces several key technologies of high-speed lifting equipment.

Abstract:本文主要阐述秦山核电二期扩建4#反应堆穹顶预应力张拉施工工艺,介绍了该项目施工的特点以及主要技术创新情况。