【摘要】 为研究钻探取样、运输及试样制备等环节对软土力学指标的扰动影响,开展了以下研究工作:首先,基于土的损伤评价理论,假设饱和软土粘聚力与结构强度成正比关系,提出损伤变量计算公式及其应用方法;然后以福州沿海软土为例,通过一系列固结试验及三轴试验,获得扰动土样及重塑土样的强度指标、压缩性指标,利用图解法推求得原位土的压缩性指标和结构强度,并藉此计算得到扰动土样损伤变量,进而对软土试样的扰动损伤进行量化分析和评价,主要结论如下:饱和软土的内摩擦角几乎不受扰动损伤影响,上述理论假设及依此建立的公式成立;对采用薄壁取土器取样,运输搬运环节采取了必要的保护措施,且严格按规范操作的试样,其损伤变量达20%以上,土样的压缩性增大约10%,粘聚力、结构强度、地基承载力下降10%左右;土样的宏观力学指标弱化不太显著,由此产生的工程设计计算结果偏差尚可接受;倘若取样、运输搬运及试验操作环节不够严谨,则试样的损伤影响必将相应放大,值得重视.更多还原

【Abstract】 To study the disturbed effect of the mechanical indexes of soft soil in the course of drilling,transport,sample preparation and other steps,firstly,based on the theory of soil damage assessment,the assumption of cohesive force proportional to the structural strength for saturated soft soil was supposed which derives the damage variable formula and its application method. Secondly,a series of consolidation tests and three triaxle tests were conducted for Fuzhou coastal disturbed and remolded soft soil samples,and their strength and compressibility index were obtained,then the compression index and the structural strength of undisturbed soil were ascertained by using graphic method, thereby the disturbed soil sample’s damage variable was calculated. Based on above works,the damage effects of soft soil sample were analyzed and evaluated quantitatively,and the results show that the internal friction angle of saturated soft soil is almost not affected by the influence of disturbance damage,so the above theoretical assumption and accordingly the established formula are valid;the damage variable is more than 20% and the compression of soil samples increases about 10%; the cohesion,structural strength and the foundation bearing capacity decrease about 10%. It is necessary to take protective measures in transport process and operate strictly according to the standards in tests. the weakness macro-mechanics indexes of soft soil sample is not obvious,so the difference between calculation results can be accepted in engineering practice;if the sampling,transport and test operation link is not rigorous,the sample damage effect will be corresponding amplification, which is worthy of attention.更多还原