Dolosse

DOLOSSE DIMENSIONS (A)

DOLOSSE DIMENSIONS (A)

DOLOSSE DIMENSIONS (B)

Dolos (wave-dissipating concrete block used to built revetments for protection against the erosive force of waves), was invented by Merryfield, E. M, a harbor engineer in East London, South Africa. It became the most popular artificial veneer block for its small amount of concrete and easy construction. The block was composed of three slender rods. At first, the section of each bar of the block is octagonal, and later, the section of the block is hexagonal. When we adopt this kind of block, the section has been changed to circular. This is easy to manufacture and will not change the original characteristics of the block.

Application Design

Dolosse surface protection need to lay two layers, because the upper and lower end of the bar is perpendicular to each other, when placed, one end should be parallel to the embankment slope, which placed above the embankment slope. The other end is perpendicular to the embankment slope, which placed below the embankment slope for increasing the anti-tipping moment of the block and is conducive to the stability of the protection layer.

According to the relevant specifications, when the dolos is placed regularly, the vertical bar should be placed below the slope and pressed on the cross bar of the front block, which is placed on the bedding blocks, and the waist bar is straddled on the cross bar of the adjacent block, as shown in the following figure.

In the precast construction of dolos, horizontal construction is superior to vertical one in equipment. The vertical construction efficiency is better than the horizontal one in the formwork disassembling and assembling process. Vertical wipe speed is higher than horizontal, but wipe quality control is more difficult than horizontal. Vertical prefabricated surface bubbles is slightly more than horizontal. Vertical precast construction efficiency is higher than horizontal precast. It is known that: vertical and horizontal prefabrication have applicability, which should be selected according to the site situation, resource allocation and construction period requirements.

Main Feature

The purpose of the invention of the dolos is to take advantage of the characteristics of the slender bar block, which requires less concrete, large voidage and good interlocking. These advantages are more prominent where the water is shallower and the waves are smaller.

Dolos is a block composed of three slender bars, and its stability is mainly shown by their interlocking action. Therefore, the placement of the block largely determines the stability. There are two types of block placement: random placement and regular placement. The former is convenient in construction and fast in cycle, but the block interlocking effect is poor. The latter can be roughly divided into two forms: one is that the transverse strut is parallel to the dike axis, and the other is that the transverse struts are at an angle of 12~45° with the dike axis. Block placement should avoid strong waves acting diagonally on the block.

Application Scenario

Since its appearance, dolos has experienced more than 20 years of research and use, the basic characteristics have been obvious. Research methods, design process, construction and maintenance experience has gradually matured. Although dozens of new types of blocks have been proposed worldwide, dolos is still widely used and further studied and improved for its unique advantages. The biggest flaw of the dolos is that it is easy to break in the weak place when it wobbles and rolls under bad sea conditions. However, in the coastal area of China, due to the natural shielding effect of the dry vast continental shelf and coastal islands, the wave is relatively small, the wave height is generally less than 7m, and the stable weight of the dolos is basically within 10t, so its weakness is not very obvious. It has been applied in a large number of projects such as Qingdong Artificial Island of Shengli Oilfield, Majishan Port dike project of Baosteel, and the third phase of Qinhuangdao Port coal Wharf.