The ring girder may be slightly distorted before it is completely destabilized. If the Larsen
sheet piling offer a certain degree of flexural deformation, the double-wall sheet piling cofferdam and the grid-shaped cofferdam on the ring beam are gravitational support structures. They can be double-walled double- The cofferdam may also be a lattice cofferdam. The stability of the two cofferdams depends on the characteristics of the fillers, the subsoil, and the arrangement and type of the sheet piles. This cofferdam is often used to Temporarily close the dock entrance, the formation of dry construction site, can also be used for artificial island wall pier and other permanent structure.
In this case,
Example of a single-row sheet piling cofferdam In this example, the soil parameters are the same as those in Chapter 2, and the Larsen sheet piling is 790m in depth. This example includes many aspects of cofferdam design. Design cofferdam need to Try again and again, especially the support layout, with a computer calculation will be more convenient, here only hand calculation to elaborate on the calculation process.
In this case,
The distribution of soil layer and its related characteristics, the water level on both sides of sheet pile and the final excavation surface. The active earth pressure has been calculated in the example. Because of the temporary enclosure, the passive earth pressure per excavation surface is Calculated by the short-term total stress condition.
The construction sequence is as follows:
(1) application of sheet piling, precipitation excavation to the first support lower;
(2) installation of the top support, excavation, precipitation to the second support lower;
(3) installation of bottom support, excavation to the the elevation
In this example, the second support is assumed to be hinged, thus simplifying the problem to a statically determinate structure. Based on this assumption, the retaining wall can be divided into two single-braced enclosures. It is also assumed that the excavation process can Strictly control the excavation marg- eland elevation is not considered in the inter-working conditions in the over-digging, the ultimate consideration of 020m over-digging conditions.
Conditions: excavation to the top of the support before the installation of the top support, Larsen u-type sheet piling manufacturers for the cantilever structure, assuming excavation, sm depth, at this time of the earth pressure distribution shown in Figure 55. Obviously , The follow-up conditions in this case, the required length of sheet piling and bending strength much larger than the conditions, so the conditions need not be added.
