似粘聚力对砂土地层成孔性影响分析
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摘要
工程上处理砂土地层作为持力层时,多将其视为粘聚力为零的无粘性土,这种忽视似粘聚力存在的做法过低得估计了土体强度,使得设计参数相对保守,工程造价也因此增加。此外,在砂土地层的基坑中采用土钉支护时,成孔不易,容易坍塌,无法正常施工。本文通过引进非饱和砂土的似粘聚力,采用力学方法对砂土地层进行稳定性分析,得到了砂土地层在孔洞挖成后重分布的应力场及位移场,并且以西安某大厦基坑支护项目为依托,结合Flac3D数值模拟来进行成孔稳定性的分析研究。结果表明,砂土地层的成孔性与砂土似粘聚力相关,在一定的密实度下,砂土的似粘聚力与其含水率有关。在工程实践中,可通过改变砂土含水率来保证砂土地层的土钉成孔。
When treating sand layer as a bearing layer,it is regarded as a non-cohesive soil with zero cohesion. This neglect of cohesive force is too low to estimate the strength of the soil,which may lead to relatively conservative design parameters and high engineering cost. In addition,when soil nailing is used in the foundation pit of the sand layer,the hole is not easy to form,and it is easy to collapse and cannot be properly constructed. By introducing the cohesive force of unsaturated sand,In this paper,the mechanical method is used to analyze the stability of the sand layer. The stress ?eld and displacement field redistributed after the hole-forming are obtained.,Based on the foundation pit support project of a building in Xi'an,the pore stability is analyzed by numerical simulation software Flac3 D. The results show that the pore-forming property of sand-soil layer is related to the clay-like cohesive force.Under a certain degree of compactness,the cohesive force of sand is related to its water content. In the engineering practice,the soil nailing of the sand layer can be ensured by changing the moisture content of the sand.
When treating sand layer as a bearing layer,it is regarded as a non-cohesive soil with zero cohesion. This neglect of cohesive force is too low to estimate the strength of the soil,which may lead to relatively conservative design parameters and high engineering cost. In addition,when soil nailing is used in the foundation pit of the sand layer,the hole is not easy to form,and it is easy to collapse and cannot be properly constructed. By introducing the cohesive force of unsaturated sand,In this paper,the mechanical method is used to analyze the stability of the sand layer. The stress ?eld and displacement field redistributed after the hole-forming are obtained.,Based on the foundation pit support project of a building in Xi'an,the pore stability is analyzed by numerical simulation software Flac3 D. The results show that the pore-forming property of sand-soil layer is related to the clay-like cohesive force.Under a certain degree of compactness,the cohesive force of sand is related to its water content. In the engineering practice,the soil nailing of the sand layer can be ensured by changing the moisture content of the sand.
引文
[1]董建军,赵超.不同含水率下非饱和细粒尾矿土的强度与变形实验研究[c].北京:非饱和土的应力-强度理论与变形特性学术研讨会.2016.
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[3]李宣,孙德安.非饱和砂土和粉土的抗剪强度及其预测[J].工业建筑. 2017(3):102-105.
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[6]蔡国庆,车睿杰,孔小昂,等.非饱和砂土抗拉强度的试验研究[J].水利学报. 2017(5):623-635.
[7]刘丰收.非饱和砂土的表观粘聚力研究[J].水利水电科技进展.2001.
[8]张鹏程,汤连生,姜力群,等.基质吸力与含水量及干密度定量关系研究[J].岩石力学与工程学报.2013(增刊1):2792-2797.
[9]唐辉明.工程地质学基础[J].北京:化学工业出版社.2007.
[2]崔頔.非饱和砂土的表观粘聚力研究[J].北方交通.2014(2):86-87.
[3]李宣,孙德安.非饱和砂土和粉土的抗剪强度及其预测[J].工业建筑. 2017(3):102-105.
[4]庞冬.土钉支护技术在砂土基坑中的应用[D].西安:长安大学.2017.
[5]张平,殷洪建,吴昊.非饱和土砂土湿吸力[J].辽宁工程技术大学学报.2011,30(3):389-391.
[6]蔡国庆,车睿杰,孔小昂,等.非饱和砂土抗拉强度的试验研究[J].水利学报. 2017(5):623-635.
[7]刘丰收.非饱和砂土的表观粘聚力研究[J].水利水电科技进展.2001.
[8]张鹏程,汤连生,姜力群,等.基质吸力与含水量及干密度定量关系研究[J].岩石力学与工程学报.2013(增刊1):2792-2797.
[9]唐辉明.工程地质学基础[J].北京:化学工业出版社.2007.