1 General Provisions
1.0.2 The structural type of breakwaters not only covers common slope and vertical type (the breakwater body is of normal placed block, rectangular caisson, perforated caisson, cylinder or pile), but also open, semi-circular type, etc. In recent years, there has been relatively mature practical experience in semi-circular breakwater at home; although the open type breakwater has been obtained with some experience, it is still in a test research stage.
In accordance with the technical development of harbour engineering and the domestic service experience, this code mainly makes provisions for common mound breakwater (including rubble submerged breakwater) and vertical breakwater. The appendixes of this code have given the relevant provisions for open wave dissipation caisson and semi-circular breakwater, and given principled provisions for cylinder, piled and open type breakwater.
Other hydraulic structures bearing wave action in the provisions cover diversion dike, sand control dam, diking, revetment, etc.
3 Basic Requirements
3.1 General Requirements
3.1.1 Where the axis of the breakwater staggers outside the harbour, the wave energy will concentrate at the nook where the breakwater body damage is the most serious. In accordance with the foreign practical experience, when the external included angle is greater than 150°, the wave energy concentration is not obvious.
3.1.2 With the advances in science and technology and the development of social economy as well as the higher demand of people on material culture, more and more attention to the coordination with environment and the comprehensive utilization of marine environment, the landscape effect and hydrophilicity of marine structures are favoured by more and more people, and the domestic landscape protection engineering which has been implemented in recent years has been obtained with good technical, economic and social benefits.
The semi-circular breakwater and piered open type breakwater are incorporated into this code according to the existing practical experience.
3.1.6 The breakwater is an engineering with complex boundary condition and higher risk and significance; the calculation theory is imperfect, so a model test verification is specified.
3.1.7 This article specifies the breakwater shall not only be subjected to settlement, displacement and other observations under severe natural condition and higher building significance, but also protomer observation work such as wave runup and wave force if conditions permit, so as to accumulate actual engineering data, sum up experience and continuously improve design and construction level.
3.2 Breakwater Design
3.2.4 The wave is a gravity one, but irregular. In the present model test, the previous regular wave is replaced with irregular wave, which is closer to the reality. However, the regular wave is adopted sometimes to observe the wave pressure of breast wall of vertical breakwater and mound breakwater and to verify the stability, for the purpose of synchronous comparison under the action of irregular wave.
3.3 Breakwater Construction
3.3.1 The breakwater is located in the open sea area, and its construction is greatly influenced by wind, wave, flow, ice, fog, etc., which is the direct cause of the increase of engineering cost, even the engineering loss. Therefore, field survey shall be carried out before construction, and the main factors having an influence on the construction shall be analyzed, so as to provide basis for scientifically and reasonably determining the construction scheme.
3.3.2 The construction section, construction sequence and procedure overlapping length for the breakwater construction are very important to the safety during the breakwater construction. This provision is made with a view to preventing or reducing the engineering loss caused by wind wave, in particular gust.
3.3.7 The current professional standards have no unified definition or specific provision on the stone material used for port and waterway engineering; in recent years, there are many disputes on a few engineerings due to the difference of the knowledge and master of the stone material. So the classification, processing and specification of the common stone material used for the breakwater are defined in accordance with the requirements of various regions and in combination with the practice of port and waterway industry as well as the relevant requirements and the explanation of the relevant professional standards.
4 Design of Mound Breakwater
