为了获得广东珠江口海洋软土的不排水抗剪强度，分别开展了不固结不排水剪切和固结不排水剪切三轴试验、无侧限抗压试验、现场取土离心机正常固结模型地基的T-bar静力贯入试验以及现场十字板剪切试验和静力触探试验（CPT），并采用土力学经验公式进行计算，确定了珠江口海洋软土不排水抗剪强度沿深度的分布规律，并综合评价了各种方法的有效性。为了获得该区域软土的循环弱化规律，分别开展了循环动三轴试验、现场取土离心机正常固结模型地基的T-bar循环贯入试验和现场单桩水平循环加载试验，揭示了软土循环动模量比与循环次数之间的双对数线性关系，获得了3种试验条件下珠江口海洋软土的循环弱化因子。其研究结果可为该区域海洋建筑物设计提供直接依据，也可为其他类型工程提供借鉴。

To obtain the static undrained shear strength of the saturated marine soft clay in the Pearl River Estuary in Guangdong, a series of tests are conducted, i.e. the unconsolidated undrained (UU) shear tests, the consolidated undrained (CU) shear tests, the unconfined compression tests, the static T-bar penetration tests in the centrifuge model foundation of normally consolidated soft clay, the field vane shear tests, and the cone penetration tests (CPTs); empirical formulations of soil mechanics are also employed. Based on these tests and calculations by the formulations, the distribution patterns of the undrained shear strength of the marine soft along with the depth clay are determined and the validity of different methods mentioned before are evaluated comprehensively. In order to acquire the cyclic degradation behaviors of the marine soft clay in this area, cyclic triaxial tests, cyclic T-bar penetration tests in the centrifuge model foundation of normally consolidated soft clay, and cyclically horizontal loading tests on a single pile in the field are carried out respectively. It is found that there is a double logarithm linear relationship between the cyclic secant modulus ratios of the soft clay and the number of cycles, from which three types of degradation factors for three testing condtions are achieved. The results can provide a guide for the offshore structure design in this area, and can also be used for reference in other engineering projects.