Journal of Shandong University(Engineering Science) ›› 2025, Vol. 55 ›› Issue (4): 84-92.doi: 10.6040/j.issn.1672-3961.0.2024.015

• Civil Engineering • Previous Articles    

The spatial distribution of unsaturated soil and support design method of urban subway foundation pit

LI Lianxiang1,2,3, GUO Longde1,2, WANG Kunyi4, WANG Peiyan1,2, CHE Xiuxi1,2, QIU Yefan1,2   

  1. LI Lianxiang1, 2, 3, GUO Longde1, 2, WANG Kunyi4, WANG Peiyan1, 2, CHE Xiuxi1, 2, QIU Yefan1, 2(1. Research Center of Foundation Pit and Deep Foundation Engineering, Shandong University, Jinan 250061, Shandong, China;
    2. School of Civil Engineering and Water Conservancy, Shandong University, Jinan 250061, Shandong, China;
    3. Shandong Hi-Speed Geotechnical Engineering Co., Ltd., Jinan 250102, Shandong, China;
    4. China Railway 17th Bureau Group First Engineering Co., Ltd., Qingdao 030006, Shandong, China
  • Published:2025-08-31

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Abstract: In order to promote the application of unsaturated soil theory in foundation pit support design, the thickness distribution of urban unsaturated soil was defined based on Jinan City. A simplified soil-water characteristic curve suitable for Jinan unsaturated soil was established by using matrix suction monitoring and unsaturated soil strength test data. Based on the total cohesion method, the formula of horizontal resistance coefficient and soil pressure of unsaturated soil in support structure expressed by soil saturation was derived, and the general design method of unsaturated soil support suitable for practical engineering application was obtained. The applicability of this method was demonstrated by using a subway foundation pit case. The case analysis showed that the internal force and displacement of the supporting structure calculated by the unsaturated soil theory were greatly reduced compared with the saturated soil theory, and were closer to the actual monitoring value. The research result showed that under the current engineering investigation level, the typical matrix suction measurement could be used to obtain and simplify soil-water characteristic curves in urban areas, establish the relationship between saturation and matrix suction, and complete the support design of unsaturated soil foundation pit, which could provide references for the design of urban unsaturated soil foundation pit.

Key words: unsaturated soil, foundation pit engineering, support design, soil-water characteristic curve, matric suction

CLC Number: 

  • TU92
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