Abstract:This paper introduces the preliminary design of the Henan section of the South-to-North Water Diversion Project, which proposes the 1:5 simulation model test of the large-scale prestressed concrete ferry structure with a span of 40m and a double-box rectangular section, and analyzes and discusses the key technical problems such as the simulation of the structural self-weight and the establishment of the initial stress state before the structure is subjected to the water load, and the method of applying the water load. The key technical issues such as the method of water load application are analyzed and discussed. The test results show that it is feasible to use the method of adjusting the initial prestress of concrete to simulate the stress state of the prestressed concrete ferry structure under the action of structural self-weight, and that the use of single-cavity and multi-cavity loading bladders composed of single-sided rubber and steel structures can accurately simulate the action of water load in the ferry, and the use of a fully automated data acquisition and processing system is the necessary equipment to ensure that the data acquisition of the large-scale structural model test is synchronized and accurate. The use of fully automatic data acquisition and processing system is necessary to ensure the synchronization and accuracy of data acquisition in large-scale structural model tests, which provides important successful experience for large-scale prestressed concrete structure model tests. With regard to the performance test results of the main components in the single and double tanks, the design methods and structural measures of each component are proposed, as well as the structural design suggestions for further improvement.

Abstract:Xiaolangdi sand exclusion cave is the first case of hydraulic tunnel lined with double-ring surrounded non-bonded prestressed concrete in China, this paper gives a brief introduction to this new structural form and characteristics, and according to a large number of measured data obtained by the observation instrument, it discusses the effective prestressing force changes in the concrete lining and anchors in the different phases (prestressing force application, backfill grouting and over-water operation) and the change rule of concrete creep. The measured data show that the double-ring encircling unbonded prestressing technique can realize ideal prestressing effect and uniform ring stress distribution. The quality of the surrounding rock excavation has an important influence on the uniformity of the ring prestress distribution; for the actual structure that takes a long time to apply prestressing, the creep strain of the concrete occupies a non-negligible proportion in the total strain change of the observation instrument, and its size and the pre-compressive stress and the holding time are linearly related to the pre-compressive stress and the holding time, and can be measured by? =? ∑?iti can be calculated. The measured data of the over-water operation stage show that the precompressive stress established in the concrete lining of the project is sufficient to resist the internal water pressure at the maximum design operation level without cracking or seepage.

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Abstract:This paper briefly describes the functional advantages of small-diameter bored anti-slip piles according to the viewpoint of geo-engineering, the basic viewpoints that should be followed in the research, and illustrates the design principles through engineering examples, showing the prospects of popularizing and applying this technology.

Abstract:There are some difficulties in the construction of large tonnage anchor holes in the complex stratum of high slopes. This paper introduces a combination of submerged hammer and pipe drilling and bottom reaming construction method, which can be used to drill larger anchor holes with lighter drilling rigs.

Abstract:With the development of China's highway, single column pier prestressed cover beam will be widely used in highway bridge project. But for the terrain, geological conditions of the complexity of the tall single column pier prestressed cover beam, if the conventional bracket method (steel pipe frame method) construction, there is a series of problems such as high investment, long cycle, technical difficulties. To this end, the author combined with Chang (De) Zhang (Jiajie) highway dog beach bridge project construction, recommended the introduction of bracket supporting mold technology in a single pier prestressed cover beam construction and construction process, can be similar to the future bridge project construction to provide technical reference.

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