王宽君, 吴昊, 倪卫达, 许小路, 黄子炎. 2021: 基于CPTU的广东海域黏土工程特性评价. 工程地质学报, 29(S1): 191-202. DOI: 10.13544/j.cnki.jeg.2021-0472
    引用本文: 王宽君, 吴昊, 倪卫达, 许小路, 黄子炎. 2021: 基于CPTU的广东海域黏土工程特性评价. 工程地质学报, 29(S1): 191-202. DOI: 10.13544/j.cnki.jeg.2021-0472
    WANG Kuanjun, WU Hao, NI Weida, XU Xiaolu, HUANG Ziyan. 2021: ENGINEERING PROPERTIES ASSESSMENT OF MARINE CLAY IN GUANG-DONG OFFSHORE AREA BASED ON CPTU. JOURNAL OF ENGINEERING GEOLOGY, 29(S1): 191-202. DOI: 10.13544/j.cnki.jeg.2021-0472
    Citation: WANG Kuanjun, WU Hao, NI Weida, XU Xiaolu, HUANG Ziyan. 2021: ENGINEERING PROPERTIES ASSESSMENT OF MARINE CLAY IN GUANG-DONG OFFSHORE AREA BASED ON CPTU. JOURNAL OF ENGINEERING GEOLOGY, 29(S1): 191-202. DOI: 10.13544/j.cnki.jeg.2021-0472

    基于CPTU的广东海域黏土工程特性评价

    ENGINEERING PROPERTIES ASSESSMENT OF MARINE CLAY IN GUANG-DONG OFFSHORE AREA BASED ON CPTU

    • 摘要: 海洋岩土参数作为海上风机基础设计的重要部分,其参数评价直接影响风机安全运行及工程造价。孔压静力触探试验(CPTU)作为目前海洋岩土工程使用最广泛的原位测试手段之一,其缺点是无法直接测得土体参数,需通过解译过程获取黏土强度,如何选取准确的黏土强度的CPTU解译参数,是亟待解决的难题。本文依托广东某海上风电工程项目,开展了原位CPTU和便携式十字板剪切、袖珍贯入仪、室内微型十字板剪切、三轴UU、固结快剪、三轴CU 6种强度试验,通过线性回归得到了广东海域的黏土强度剖面,并发现60 m以下黏土的扰动较为严重,采用固结快剪和三轴CU试验可降低扰动影响;以不同强度试验结果为基准值,得到了黏土强度CPTU解译参数Nkt的平均值,采用标定得到的Nkt参数对黏土强度进行解译发现,其结果与线性回归得到的黏土强度剖面吻合较好,建议采用Nkt=21.68作为强度下限值解译参数,采用Nkt=15.75~17.83作为最优强度(中值)解译参数,采用Nkt=13.63作为强度上限值解译参数。采用竖向有效应力将黏土强度进行无量纲化后,得到了广东海域正常固结黏土无量纲化强度su/σ' v0=0.298,通过CPTU对超固结比OCR进行解译后,结合SHANSEP法得到的黏土强度结果与室内试验吻合较好,可在今后的海上风电项目中作为解译方法进行推广应用。

       

      Abstract: As an important part of offshore wind turbine foundation design, the marine soil parameter evaluation would directly affect the safety of wind turbine and project cost. At present, piezocone penetration test(CPTU) is one of the most widely used in-situ testing methods in offshore geotechnical engineering. The disadvantage of CPTU is that soil parameters cannot be directly measured, which could only be interpreted by raw data. How to select appropriate CPTU interpretation parameter of clay strength is a difficult problem to be solved at present. In this paper, based on an offshore wind project in Guangdong offshore area, in-situ CPTU and hand torvane shear, pocket penetrometer, miniature laboratory vane shear, triaxial UU, consolidated quick shear and triaxial CU tests were carried out, the strength profiles were obtained by linear regression of the laboratory test results, where the clay samples under 60m were found to be severely disturbed, consolidated quick shear and triaxial CU test could reduce the effect of disturbance. Based on the hand torvane shear, pocket penetrometer, miniature laboratory vane shear, triaxial UU, consolidated quick shear and triaxial CU tests results, the average values of CPTU interpretation parameters Nkt for clay strength are obtained as 21.68, 19.52, 17.83, 18.63, 15.73 and 13.63, respectively. We suggest using Nkt of 21.68 as the interpretation parameter for the lower bound limit, Nkt of 15.75 to 17.83 as the best estimate, and Nkt of 13.63 as the upper bound limit. By using the calibrated Nkt parameters for clay strength interpretation, it is found that the interpretation results are in good agreement with the linear correlated strength profile. By normalised by the vertical effective stress, the normalised undrained shear strength su/σ'v0 is obtained as 0.298 for normally consolidated clay in Guangdong offshore area. After interpretation of overconsolidation ratio by CPTU data, the clay strength obtained by SHANSEP method is also in good agreement with laboratory test results, which can be applied in offshore wind power projects in the future.

       

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