An extensive network of multilevel vibrating-wire piezometers (VWP) was recently created to monitor the spatial and temporal variation of pore pressure (and hydraulic head) in the landslide-prone post-glacial marine clay slopes in Québec, Canada. Some of the VWP installations used well-sorted crushed stone as well backfill between bentonite plugs, instead of bentonite pellets or cement-bentonite grout, which could cause a bias in the hydraulic head measurements due to preferential flow within the backfill (i.e., a hydraulic short circuit). This study uses steady-state two-dimensional radial-coordinate numerical models to quantify the extent of this potential bias, and focuses on the relative importance of the following components: hydraulic conductivity of the crushed stone, length of the backfill intervals, length of the bentonite plugs, magnitude and direction of the vertical gradient, and the degree of vertical and horizontal anisotropy within the clay. Simulation results show that the use of crushed stone as backfill results in measurements of hydraulic head that differ from undisturbed conditions by ±0.25 to ±210 cm, regardless of the values assigned to the parameters of interest. In all cases, the cause of this bias is a series of hydraulic short circuits resulting from preferential flow through the crushed stone intervals.

最近创建了一个广泛的多级振弦式压力计 (VWP) 网络，用于监测加拿大魁北克省易发生滑坡的冰后海相粘土斜坡的孔隙压力（和水头）的空间和时间变化。一些 VWP 装置使用分选良好的碎石以及膨润土塞之间的回填，而不是膨润土颗粒或水泥-膨润土灌浆，由于回填物中的优先流动（即水力短路）。本研究使用稳态二维径向坐标数值模型来量化这种潜在偏差的程度，并重点关注以下组件的相对重要性：碎石的水力传导率、回填间隔的长度、膨润土塞，垂直梯度的大小和方向，以及粘土内部垂直和水平各向异性的程度。模拟结果表明，使用碎石作为回填土会导致水头测量值与未受干扰的条件相差 ±0.25 至 ±210 cm，无论分配给相关参数的值如何。在所有情况下，这种偏差的原因是由于优先流过碎石层段而导致的一系列液压短路。