深厚软粘土地基沉降的离心模型实验研究

Study on Foundation Settlement of Deep Soft Clay with Centrifugal Model Tests

考虑大连新海上机场的实际工程特点,提出合理的简化模型,采用鼓式离心模型实验,有效地模拟了深厚软粘土地基的长期沉降,同时考察了回填速率、柔性加载幅值和地基厚度及固结时间对沉降的影响。通过实验拟合获得了长期沉降过程中土体不排水剪切强度随含水率的变化关系,分别运用一维固结理论和对数曲线模型推求了时程沉降及最终沉降的理论值,并与离心模型实验结果进行了对比分析。结果表明,回填速率越快,加载幅值越大,地基厚度越大,固结时间越长,对应沉降量越大。同时经过55 a的长期沉降模拟,孔隙水压力尚未消散完毕,沉降仍在继续。对数曲线模型预测地基的工后沉降更为合理,为实际工程建设提供了可靠的技术参考。

According to the practical condition of the new Dalian offshore airport ,a properly simplified model was pro-posed to effectively simulate the long-term settlement of the deep soft clay foundation with the use of a drum-shaped cen-trifugal machine .Meanwhile ,the influences of backfilling rate ,flexible loading amplitude ,foundation thickness and consolidation time on the settlement were discussed . Through the test , the interaction between the undrained shear strength and water content of the clay in the process of long-term settlement was studied .The theoretical values of time-dependent and final settlement were derived with the help of one-dimensional consolidation theory and logarithmic curve model ,and then compared with those obtained from the centrifugal model test .The results reveal that with the increasing of the backfilling rate ,the loading amplitude gets wider ,foundation thickness gets deeper ,consolidation time becomes longer and the corresponding settlement becomes larger .In the meantime ,pore pressure still exits and the settlement is still ongoing after the long-term settlement simulation of 55 years .The logarithmic curve model has a better capacity of settlement prediction after the construction ,thus provides reliable technical references for engineering construction .