A field test was conducted on vacuum treatment effects of a dredged slurry ground considering three PVD spacing, i.e., 700, 800, and 900 mm. The settlement and the pore water pressure dissipation were measured during the treatment period. As expected, the consolidation rate associated with closer PVD spacing case is higher than that of the larger spacing case. However, it is observed that the final and stable values of the settlement and the pore pressure dissipation of the close spacing case (e.g., 700 mm) are about 17% higher than the case of larger PVD spacing (e.g., 900 mm). The differences imply that enlarging the PVD spacing not only impedes the consolidation rate but also decreases the vacuum pressure in slurry. Numerical models incorporating the vacuum pressure attenuation effect and the clogging effect were established to reproduce the vacuum treatment process under the three PVD spacing. Good comparisons between the numerical and test results can be obtained given a proper account of vacuum attenuation and the clogging effect along the PVD depth. The comparison clarifies that, for vacuum treatment of slurry ground, the PVD spacing should be determined by due considerations both on the desired consolidation rate and on the pore water pressure that needs to be dissipated.

中文翻译：

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PVD间距对疏浚泥浆真空处理效果影响的现场试验与数值研究

对疏浚泥浆地面真空处理效果进行现场试验，考虑三种PVD间距，即700、800和900 mm。在处理期间测量沉降和孔隙水压力消散。正如预期的那样，与更近 PVD ​​间距情况相关的固结率高于较大间距情况。然而，据观察，紧密间距情况（例如，700 毫米）的沉降和孔隙压力耗散的最终和稳定值比较大 PVD ​​间距（例如，900 毫米）的情况高约 17%。这些差异意味着增大 PVD ​​间距不仅会阻碍固结速率，还会降低浆液中的真空压力。建立了结合真空压力衰减效应和堵塞效应的数值模型，重现了三个 PVD ​​间距下的真空处理过程。适当考虑真空衰减和沿 PVD ​​深度的堵塞效应，可以获得数值和测试结果之间的良好比较。比较表明，对于泥浆地面的真空处理，PVD 间距应通过适当考虑所需的固结率和需要消散的孔隙水压力来确定。