1964 The Niigata earthquake in Japan caused the collapse and settlement of many buildings. What is the reason?

Cause: It is located on soft foundation.

Soft soil foundation refers to the foundation mainly composed of silt, muddy soil, flushing fill, miscellaneous fill or other highly compressible soil layers. The natural water content of this foundation is too large, the bearing capacity is low, and it is easy to slide or consolidate and settle under load.

When the foundation compression layer is mainly composed of silt, muddy soil, flushing fill, miscellaneous fill or other highly compressible soil layers, it should be designed according to soft foundation. When there is high compressibility soil layer in the local area of building foundation, it should also be considered as local soft soil layer.

Extended data

If soft foundation is encountered in engineering construction, it should be comprehensively considered according to the geological conditions of the construction site, the load required by the railway grade track type, environmental conditions and air. It is necessary to collect data on geology, topography, geomorphology, engineering geology, hydrogeology and meteorology along the line, and adopt the methods of comprehensive investigation, test and comprehensive analysis.

For buildings built on soft foundation, before determining the engineering design and foundation treatment scheme, engineering geological and hydrogeological investigations should be carried out to find out the composition, geological origin, distribution range, uniformity, thickness, position and condition of bearing layer and physical and chemical properties of foundation soil.

We should also understand the uniformity and drainage consolidation conditions; For miscellaneous fill, it is still necessary to find out the historical age of stacking load and clarify the basic factors such as stability and collapsibility under self-weight; For other special soils, their characteristics, engineering properties and stratification should be found out as the basis for engineering design and selection of foundation treatment scheme.

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