非线性破坏准则下承压水地层基坑底板突涌稳定性研究
于潇1李勤兴1刘池1王洪涛2,3张华军1宣兆腾2李建华2
Stability Study of Confined Aquifer Foundation Pit Bottom Plate Inrush Based on Nonlinear Failure Criterion
YU Xiao1LI Qinxing1LIU Chi1WANG Hongtao2,3ZHANG Huajun1XUAN Zhaoteng2LI Jianhua2
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作者信息:1.济南轨道交通集团有限公司， 250100， 济南
2.山东建筑大学土木工程学院， 250101， 济南
3.山东建筑大学建筑结构加固改造与地下空间工程教育部重点实验室， 250101， 济南
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Affiliation:1.Jinan Rail Transit Group Co., Ltd., 250100, Jinan, China
2.Shandong Jianzhu University, School of Civil Engineering, 250101, Jinan, China
3.Shandong Jianzhu University, Key Laboratory of Building Structural Retrofitting and Underground Space Engineering, 250101, Jinan, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2024.02.009
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中图分类号/CLCN:U231.3； TU46+3
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栏目/Col:学术专论
摘要:
［目的］在富水岩层地区，防止承压水突涌事故已成为深基坑工程设计、施工的重点和难点，而准确有效地确定基坑底板临界厚度是防止承压水突涌事故发生的关键，因此需针对承压水地层基坑底板突涌破坏问题开展稳定性研究。［方法］基于非线性Mohr-Coulomb破坏准则，考虑地层土体各强度参数与非均质特性的影响，建立基坑底板突涌破坏力学分析模型。基于极限平衡法，提出考虑地层土体自身强度的底板突涌稳定性安全系数计算式，对现行基坑支护技术规范中的突涌破坏计算方法进行了修正。以济南某软土地层管廊工程基坑为例，验证所提出基坑底板修正突涌稳定性计算式的有效性，同时还分析了不同土体强度参数、隔水层厚度及承压水压力作用下的突涌稳定性安全系数变化情况。［结果及结论］随着土体黏聚力、非均质常数、重度及隔水层厚度的增加，基坑底板突涌稳定性安全系数不断增大；随着土体非线性系数、承压水压力及基坑宽度的增加，基坑底板突涌稳定性安全系数不断减小。考虑土体自身强度参数影响所得的突涌安全系数计算值整体大于现行基坑支护技术规范中计算方法的计算值。采用所提修正突涌稳定性计算式进行验算更为经济。
Abstracts:
［Objective］ In water-rich rock stratum regions, preventing confined aquifer inrush accidents is a key focus and challenge in the design and construction of deep foundation pit projects. Accurately and effectively determining the critical thickness of foundation pit bottom plate is crucial in preventing confined aquifer inrush accidents. Therefore, it is necessary to conduct stability study on foundation pit bottom plate inrush damage problem in confined aquifer. ［Method］ Based on the nonlinear Mohr-Coulomb failure criterion and considering the influence of various strength parameters and the heterogeneity characteristics of soil layers, a mechanical analysis model for foundation pit bottom plate inrush damage is established. Using the limit equilibrium method, a safety factor calculation formula for bottom plate inrush stability considering the inherent strength of soil layers is proposed. The calculation method for inrush damage in the current technical specifications for foundation pit support is modified. Taking the foundation pit of a utility tunnel project in soft soil layers in Jinan as example, the effectiveness of the proposed modified calculation formula for pit bottom plate inrush stability is validated. Additionally, variations in the safety factor of bottom plate inrush stability under the influence of different soil strength parameters, impermeable layer thickness, and confined water pressure are analyzed. ［Result & Conclusion］ With the increase in soil cohesion, heterogeneity constant, density, and impermeable layer thickness, the safety factor of pit bottom plate inrush stability continuously increases. Conversely, as the soil nonlinear coefficient, confined water pressure, and foundation pit width increase, the safety factor of pit bottom plate inrush stability continuously decreases. The calculated values of the inrush safety factors considering the influence of soil inherent strength parameters, are generally greater than the values obtained using the current calculation method in the technical specifications for foundation support. The verification using the proposed modified inrush stability calculation formula is more economical.
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