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| Analysis of the Classification of Weak Tunnel Foundation Soil and the Test Methods of Its Bearing Capacity |
| ZHAO Wen |
| (China Railway First Survey and Design Institute Group Co. Ltd, Xian, Shaanxi 710043 , China) |
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Abstract Research purposes： Weak foundation soil is a special kind of soil type designated between normal soil and weak soil, there is no clear definition of standards. During tunnel construction, the ubiquity of weak foundation soil has a considerable impact on the construction design. Confined to the tunnel construction site and its engineering environment, how to choose the best method to test the bearing capacity of weak foundation soil, so as to confirm the nature of the soil, arrive at the bearing capacity ASAP, validate the geological exploration results , further modify the design to provide guidances to the construction , ad ensure the project quality to meet design requirements has become a major task for engineers. Research conclusions ： (1) As a natural tunnel foundation , the weak foundation soil can hardly meet the requirements in terms of strength and deformation. (2) The weak foundation soil includes soft clayey soil , powder soil , collapsible loess , expansive soil , saturated sand , red layer , filling , etc. (3) General test methods can be used in in - situ test and laboratory test. Light dynamic penetration test or cone penetration test is recommended. (4) The research result can be applied in the field of tunnel construction and supervision.
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Received: 30 September 2015
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2015, Vol. 32 
