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| Case study on the overall stability of foundation pit slope with weak interlayer |
| LI Lianxiang1,2,3, LÜ Guiqing4, ZHANG Shangru1,2, ZHAO Yongxin1,2, WANG Chuhan1,2
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1. School of Civil Engineering, Shandong University, Jinan 250061, Shandong, China;
2. Foundation Pit and Deep Foundation Engineering Research Center, Shandong University, Jinan 250061, Shandong, China;
3. Shandong High-Xin Geotechnical Engineering Co., Ltd., Jinan 250102, Shandong, China;
4. Jinan City Urban and Rural Construction Development Service Center, Jinan 250014, Shandong, China |
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Abstract In the northern area of Jinan City, along the banks of the Yellow River, there was a layer of silty soil approximately 6 to 8 meters below the surface. A large number of landslides were observed in nearby excavations at this depth, demonstrating a different overall failure mode from the conventional circular sliding method for excavations. Based on extensive engineering landslide characteristics, a specific case analysis indicated that the slopes of excavations containing weak interlayers were subjected to a combined circular-plane overall failure mode. This conclusion was validated through numerical analysis using Plaxis finite element software. An analytical solution for the overall stability analysis of excavation slopes with weak interlayers was derived based on statics and moment equilibrium equations. The optimal support scheme was proposed and validated through numerical and monitoring data. The findings suggested that excavation slopes in geological units of the Yellow River alluvial plain in northern Jinan City were influenced by weak interlayers, exhibiting an overall failure mode of circular-plane sliding. The conventional circular sliding calculation method for excavation design posed safety risks. Therefore, the selection of excavation support structures should incorporate shear-resistant elements penetrating the weak interlayers to transform the circular-plane failure mode into circular sliding mode, thus ensuring excavation safety.
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Published: 20 September 2024
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