取样方法对饱和软土物理力学指标影响机理研究
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摘要
采用岩芯管包样、厚壁取土器和敞口薄壁取土器三种取样方法,对饱和软土常规物理力学性质指标开展了室内对比试验。基于室内对比试验成果,结合饱和软土结构和稠度特征,从组成成分变化和固结变形特性等方面对指标规律性和差异性机理进行了相关分析。研究结果表明:相对于薄壁样,岩芯管包样和厚壁样的孔隙比、含水量有所降低,密度有小幅度增大,力学指标有所提高,包样的力学指标提高幅度最大;不同取样方法下,同一饱和软土土颗粒和孔隙水比例的变化是引发指标存在差异的根本原因;饱和软土在外部荷载作用下易发生固结压缩变形,但不易产生破裂;土样固结变形量越大,含水量和孔隙比越低,密度越大,力学性质指标增大越明显。
Comparative laboratory tests on the conventional physical and mechanical properties of saturated soft soil samples obtained by three sampling methods, including core barrel, thick wall sampler and open thin-wall sampler are carried out. The regularity and differential mechanism on composition change and consolidation deformation characteristics are studied based on the test results considering the structure feature and consistency of saturated soft soil. The results show that compared with the sample obtained by thin wall sampler, the void ratio and moisture content decreases, the density increases slightly, and the mechanical index increases obviously of the samples obtained by thick wall sampler or packaging directly; the index discrepancy of the same saturated soft soil is caused by the change of void ratio and moisture content induced by different sampling methods; the saturated soft soil is prone to consolidation and compression deformation, but it is not easy to rupture under external load; the larger the soil consolidation deformation, the lower the moisture content and the void ratio, the greater the density, and the more obvious the mechanical properties increase.
Comparative laboratory tests on the conventional physical and mechanical properties of saturated soft soil samples obtained by three sampling methods, including core barrel, thick wall sampler and open thin-wall sampler are carried out. The regularity and differential mechanism on composition change and consolidation deformation characteristics are studied based on the test results considering the structure feature and consistency of saturated soft soil. The results show that compared with the sample obtained by thin wall sampler, the void ratio and moisture content decreases, the density increases slightly, and the mechanical index increases obviously of the samples obtained by thick wall sampler or packaging directly; the index discrepancy of the same saturated soft soil is caused by the change of void ratio and moisture content induced by different sampling methods; the saturated soft soil is prone to consolidation and compression deformation, but it is not easy to rupture under external load; the larger the soil consolidation deformation, the lower the moisture content and the void ratio, the greater the density, and the more obvious the mechanical properties increase.
引文
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[5] 刘华清,赵春风,高大钊. 取样扰动对土天然强度指标的影响和处理方法[J].岩土工程技术,2002,(3):158～162.Liu Huaqing,Zhao Chunfeng,Gao Dazhao. Influence of disturbed samples on soil natural strength parameter and it’ s treatment[J]. Geotechnical Engineering Technique,2002,(3):158～162.(in Chinese)
[6] 潘永坚,李高山,欧阳涛坚等. 软土地区基床系数室内试验成果影响因素分析[J].工程勘察,2016,44(7):16～21.Pan Yongjian,Li Gaoshan,Ouyang Taojian et al. Analysis on the influencing factor of soft soil subgrade reaction coefficient obtained by laboratory test [J]. Geotechnical Investigation & Surveying,2016,44(7):16～21.(in Chinese)
[7] 梁龙,蔡国成,王劲松等. 污染场地勘察钻探取样设备及工艺应用探讨[J]. 工程勘察,2018,46(7):16～21.Liang Long,Cai Guocheng,Wang Jingsong et al. Discussion on application of the equipment and technique for drilling sampling in the survey of contaminated site [J]. Geotechnical Investigation & Surveying,2018,46(7):16～21.(in Chinese)
[8] 龚序两.钻探取土的扰动影响及其预防[J].资源环境与工程,2005,19(2):105～110.Gong Xuliang. The disturbance of soil sampling by drilling and its prevention[J]. Resources Environment & Engineering,2005,19(2):105～110.(in Chinese)
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[10] 中华人民共和国国家标准.土工试验方法标准(GB/T 50123-1999)[S].北京:中国计划出版社,1999.The State Standards of the People’s Republic of China.Standard for soil test method(GB/T 50123-1999)[S]. Beijing:China Planning Press,1999.(in Chinese)
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