某沉箱码头后方强夯试验研究

在沉箱后壁设置减震沟,且将原设计的强夯区前移至距沉箱后壁12.5 m处,单点夯击能由1 500 kN.m提高到2 500 kN.m时,沿深度实测最大土压力的平均值约为设计允许值的72.8%,保证了沉箱结构不致破坏;据码头前沿的沉降、位移观测点,以及沉箱后壁外侧深层水平位移的实测值均趋于零,证明码头整体是稳定的。建议夯击能提高至2 500 kN.m,强夯区扩大至距沉箱后壁12.5 m处施工。用强夯代替了部分振冲区,既节省了投资,又提高了此处的密实度,而且突破了强夯距建筑物至少需15 m的限制。

Research on Dynamic Compaction Test at the Back of Caisson Dock

The trench is set at the back of the caisson for reducing the effect of dynamic compaction and comparing with the primary design,the test zone is 12.5 m away from the back of the caisson,the tamping energy of single point is increased to 2 500 kN.m（1 500 kN.m for design）.The maximum earth pressure is about 72.8 percent of the design value,which is assured the caisson safe.According to the settlement and displacement monitoring data of the wharf shoulder,and the lateral displacements at the back of the caisson are almost closed to zero,it is proved the dock is stable.So it is suggested that the tamping energy of single point is increased to 2 500 kN.m and the dynamic compaction zone is increased to 12.5 m away from the back of the caisson.For the construction method,the parts of vibroflotation are displaced by the dynamic compaction,which is not only saved money,but also increased the density of the foundation.At the same time,the limit between dynamic compaction zone and the building being at least 15 m is broken.