Bian Xiao sorted out the relevant contents of retaining wall foundation bearing capacity through the architectural knowledge column of the encyclopedia website "Building Network" of the construction industry. The basic situation is as follows:
Retaining wall refers to the structure that supports subgrade fill or hillside soil to prevent deformation and instability of fill or soil.
First of all, we should understand the basic requirements of retaining wall foundation bearing capacity:
The characteristic value of natural foundation bearing capacity and anti-sliding friction resistance of shallow foundation bearing layer should meet the design benchmark value.
The characteristic value of the end resistance of the bearing layer at the end of the pile foundation and the characteristic value of the friction resistance around the pile of each layer of soil should meet the design reference value.
Calculation method of characteristic value of foundation bearing capacity;
Concept of eigenvalue of foundation bearing capacity
The concept of foundation bearing capacity should be understood from two aspects: foundation soil and structure.
"The ability of foundation to bear load is called foundation bearing capacity. Usually divided into two kinds of bearing capacity, one is called ultimate bearing capacity, which refers to the bearing capacity when the foundation is about to lose stability. The other is called allowable bearing capacity, which refers to the bearing capacity when the foundation stability has enough safety and the deformation is controlled within the allowable range of the building. " The ultimate bearing capacity of foundation is not only related to the properties of foundation soil, but also related to the form, shape, buried depth and width of foundation. The allowable bearing capacity is also related to the structural characteristics of buildings and other factors.
Foundation construction should not only ensure that the basement pressure is at a safe stress level, but also control the settlement within the allowable range.
Relationship between characteristic value of foundation bearing capacity and foundation design
The basic construction procedure is "survey first, then design, then construction". The work result of the investigation unit is the geotechnical engineering investigation report (original engineering geological investigation report). The design unit shall carry out basic design according to the survey report. The foundation evaluation content of the survey report includes the bearing capacity of the foundation, which is what designers are most concerned about.
Taking shallow foundation on natural foundation as an example, the recommended value of foundation bearing capacity in the survey report can be obtained, and the fa value of foundation bearing capacity after depth and width correction can be obtained by calculation, so as to design the foundation size and carry out the follow-up work of foundation design.
In this design process, there are some incorrect tendencies. Some designers think that the suggested values in the survey report can be used with confidence, and the survey unit is responsible for any problems.
The geotechnical design parameters given in the survey report, including the recommended value of foundation bearing capacity, need a re-analysis process to be correctly understood and used, which is actually a foundation design process. It can be seen that the above design process seems logical, but it is not. The main problem is that it is easy to ignore the important link-basic design.
Both foundation evaluation and foundation calculation belong to the category of foundation design. As Mr. Gu Baohe, the master of engineering investigation, pointed out, "Although the recommended value of foundation bearing capacity is generally put forward by the investigation report at present, it is different from the geotechnical characteristics index, and its essence is the design of foundation."
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