黏土夹层对共振法加固效果影响试验研究

Experimental study on influence of clay lens on compaction effect of resonant compaction method

为研究黏土夹层对共振法处理可液化砂土地基效果的影响,按比例制备十字翼振杆并开展相关模型试验.根据加固前后轻型动力触探击数 N 10 、土颗粒峰值振动加速度 a 和砂土相对密度 D r 的变化,分析了黏土夹层对土体强度、能量传递规律及密实程度的影响.结果表明, N 10 和 a 值随着测点与振杆径向距离的增加而减小.受黏土夹层影响,加固前后土体强度增长幅度降低64%~127%, a 值也相应减少,且振动有效影响半径由0.4 m减少为0.3 m,砂土相对密实度增长幅度下降4.2%~9.7%.现场标贯试验及地表峰值振速监测结果进一步验证了模型试验的可靠性.地基中黏土夹层可使振点处的排水通道受阻,降低土体排水固结及能量传递效率,减弱了加固效果.

To investigate the influence of clay lens on the compaction effect of using the resonant compaction method to treat liquefiable sandy ground, a small scale crisscross-sharped probe model was prepared and laboratory tests were carried out. The effects of clay lens on the soil strength, the energy transferring law and the compactness were analyzed according to the change of the light dynamic cone penetration number N 10 , the relative density D r , and the peak vibration acceleration of soil particles a , measured before and after the tests. The results show that N 10 and a decrease with the increase of the radial distance between the measure point and the compaction point. Due to the existence of clay lens, the increment of N 10 decreases by 64% to 127% before and after reinforcement, and the value of a decreases accordingly. The effective radius for compaction decreases from 0.4 to 0.3 m. The increment of D r decreases by 4.2% to 9.7%. The reliability of the test is verified by the standard cone penetration tests and the peak ground velocity measurement from the field tests. The clay lens can impede the water jetting through the drainage channel,decrease the efficiency of consolidation and energy transferring during vibro-compaction, and weaken the compaction effect.