秦皇岛滨海饱和软土的试验研究

为保持饱和软土的天然结构特征，野外采用开挖探井，环刀取土的方法获得了大量Ⅰ级土试样，并在室内进行有关饱和软土的物理力学性质试验。结果表明：秦皇岛滨海饱和软土的天然含水量介于37％～44％，土性属淤泥质粉质粘土。基于浅层平板载荷试验、静力触探试验以及十字板剪切试验，对饱和软土的天然抗剪强度、灵敏度、承载力进行了试验研究。建立了十字板抗剪强度和试验深度、静力触探比贯入阻力的经验公式，为工程应用提供了便利条件。秦皇岛滨海饱和软土的天然不排水抗剪强度平均值为27kPa，灵敏度为2．4～12．5，具有中高灵敏性。其地基强度的使用应综合考虑建筑物的加载速率、地基容许变形等多种因素。

EXPERIMENTAL STUDY ON SEASIDE SATURATED SOFT SOIL IN QINHUANGDAO

In the seaside of Qinhuangdao, the surface soil usually consists of 2 - 5 meters of very soft soil layer. Its inner friction angle is very small or zero. The deformations of above saturated soil often lead to cracks in the building. In order to investigate its physical and mechanical properties, large numbers of undisturbed soil samples have been obtained with the rigid steel ring from the test pit. Laboratory tests including confined compression test and triaxial test are carded out. The seadside soft clay can be defined as silty clay, for its water content is 37% - 44%. The shear strength, sensitivity, and bearing capacity of seaside soft clay are determined in-situ by using plate loading test, cone penetration test, and vane shear test. The test results show that the shear strength of field vane test can be determined as a function of testing depth with specific penetration resistance and shear strength. The average value of undrained shear strength is 27 kPa with medium or even higher sensitivity of 2.4 - 12.5. The characteristic values of subgrade bearing capacity are less than 80 kPa. Based on the field test, allowable loads and settlements of the foundation for some buildings during consolidation are theoretically analyzed. Problems arising from some buildings constructed on the soft clay in Qinhuangdao district are presented.