基于剪切波速的海底含气沉积物卸荷扰动与样品质量评价方法  

A method for evaluating the unloading disturbance and sample quality of marine gas-bearing sediments based on shear wave velocity

作　　者：杨志勇 王勇[1,2] 孔令伟 桂彬[3] 陈楷文 YANG Zhi-yong;WANG Yong;KONG Ling-wei;GUI Bin;CHEN Kai-wen(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;College of Civil Engineering and Architecture,Guilin University of Technology,Guilin,Guangxi 541004,China)

机构地区：[1]中国科学院武汉岩土力学研究所,岩土力学与工程国家重点实验室,湖北武汉430071 [2]中国科学院大学,北京100049 [3]桂林理工大学土木与建筑工程学院,广西桂林541004

出　　处：《岩土力学》2020年第11期3687-3694,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51979269,No.51579237)。

摘　　要：海底取样相比陆域环境具有更多的样品扰动因素,样品质量的定量评价对海洋岩土工程而言显得十分重要。基于室内不排水卸荷应力路径三轴试验和弯曲元试验,针对杭州湾海底粉细砂土,模拟海底含水溶气沉积物取样过程中应力释放所引起的扰动效应,研究样品卸荷扰动前后剪切波速的变化(Vs_lab/Vs_insitu)及其与孔隙比变化率Δe/e0(Δe为扰动后孔隙比的变化,e0为初始孔隙比)的相关关系,探讨利用剪切波速方法来定量评价海底沉积物样品质量的可行性。结果表明:卸荷扰动后样品的剪切波速会发生显著的降低,Δe与卸荷幅度关系曲线呈"S型",且卸荷扰动前后剪切波速比(Vs_lab/Vs_insitu)与孔隙比变化率(Δe/e0)具有良好的关联性,剪切波速法与Lunne提出的基于孔隙比变化率的样品质量评价方法具有一致性,可为海洋岩土工程中的海底沉积物样品质量评估提供借鉴。Compared with the sampling on land,there are more disturbance factors on the sample in marine environment.Therefore,the quantitative evaluation of sample quality is of vital importance for marine geotechnical engineering.Based on the triaxial test of undrained unloading stress path and the bender element test,Hangzhou Bay marine fine sand was used to simulate the disturbance effect caused by stress release in the sampling process of marine water-soluble gas deposits.The change of shear wave velocity(Vs_lab/Vs_insitu)before and after unloading disturbance and its correlation with the rate of void ratio(Δe/e0)were investigated,and the feasibility of using the shear wave velocity method to quantitatively evaluate the quality of marine sediment samples was also discussed.The results show that the shear wave velocity of sand decreased significantly due to the unloading disturbance;and the change in void ratio of sandΔe presented a"S-shaped"curve with the increase of unloading amplitude.Moreover,the shear wave velocity ratio had a good relationship with the rate of void ratio before and after the unloading disturbance.The results of sample quality evaluation based on the shear wave velocity method are consistent with those from the method proposed by Lunne,which is based on the change rate of void ratio.This work provides a beneficial reference for the sample quality evaluation of sediments in the marine geotechnical engineering.

关 键 词：海底沉积物 样品质量 扰动 弯曲元 剪切波速 

分 类 号：TU441[建筑科学—岩土工程]