获得未受扰动的土样是岩土工程勘察中的一项挑战,而钻探取土过程中会不可避免地对土样产生一定程度的扰动。为了研究取土工艺在饱和软黏土地层中取样时对土样质量的影响,本文以浙江温州典型淤泥为研究对象,首先通过静力触探试验了解场地地层的分布情况,然后分别使用隐形轴阀式取土器、常规厚壁取土器和敞口式薄壁取土器的取土工艺进行取土对比试验。通过对土样的外观形态、无侧限抗压强度和灵敏度指标、扰动性指标进行比较分析研究,最终得到不同取土工艺对饱和软黏土取土质量影响的定量分析评价。结果表明:采用隐形轴阀式取土器的取土工艺采取土样的扰动性相对最小,取土质量相对最高,敞口式薄壁取土器次之,常规厚壁取土器采取土样的扰动性相对最大,取土质量相对最差;隐形轴阀式取土器所取土样的无侧限抗压强度平均值比常规厚壁取土器高20.2%,比敞口式薄壁取土器高10.3%;利用自重应力下的孔隙比变化率作为土样扰动性大小的定量指标,取土质量相对最差的常规厚壁取土器所取土样的孔隙比变化率平均值比最好的隐形轴阀式取土器增大11.0%;隐形轴阀式取土器在饱和软黏土中采取的土样质量相对最高,试验后得出的岩土参数相对最接近于真实地层的物理力学特性。

Obtaining undisturbed high-quality samples is a challenge in geotechnical investigation, and soil samples will be disturbed to some extent in the process of drilling and sampling. In order to study the influence of sampling technology on the quality of soil samples when sampling in saturated soft clay strata, this paper takes a typical silt in Wenzhou, Zhejiang Province, as the research object. Firstly, the stratigraphic distribution of the site was understood by cone penetration test (CPT). Then, comparative tests on the quality of soil samples were conducted by using cryptomorphic shaft-valve type soil sampler, conventional thick wall sampler and open end thin wall sampler, respectively. Through a comparative analysis and research on the appearance morphology, unconfined compressive strength and sensitivity index, disturbance index of soil samples, a quantitative analysis and evaluation of the influence of different sampling technology on the quality of soil sample of the saturated soft clay was finally obtained. The results of the study showed that using the cryptomorphic shaft-valve type soil sampler has the least disturbance and the highest quality on sampling, the open end thin wall sampler is the second, and the conventional thick wall sampler has the highest disturbance and the worst quality. The cryptomorphic shaft-valve type soil sampler has 20.2% higher unconfined compressive strength average value than the conventional thick wall sampler and 10.3% higher than the open end thin wall sampler. Using the rate of change of pore ratio under self-weight stress as a quantitative indicator of the magnitude of soil sample disturbance, the conventional thick wall sampler with the worst soil quality has 11.0% greater than the average value of the best cryptomorphic shaft-valve type soil sampler. The sampling technology of the cryptomorphic shaft-valve type soil sampler takes soil samples of relatively highest quality in saturated soft clay, and the geotechnical parameters obtained after the test are relatively close to the physical and mechanical characteristics of the real stratum.