Department of Civil and Environmental Engineering, São Paulo State University, Bauru 17033-360, SP, Brazil.
Advanced Campus of Ilha Solteira, Federal Institute of São Paulo, Ilha Solteira 15385-000, SP, Brazil.
Sensors (Basel). 2023 Jan 27;23(3):1429. doi: 10.3390/s23031429.
The plate load test (PLT) is the most reliable in situ testing for studying the load-settlement behaviour of footings on unsaturated collapsible soils. In these soils, the suction profile is not constant along the depth, and the scale effect between the prototype and footing leads to different suction averages and, consequently, different data. One method to eliminate the effect of soil suction on the test data is to fully saturate the soil prior to the test, which is also recommended at the design process for footing on collapsible soils. However, the inundation process on PLTs is expensive and time-consuming, which makes this procedure difficult to incorporate into engineering practice. This study presents a device that can be attached to flat dilatometer (DMT) to allow local inundation of the soil as part of the in situ test campaign and obtain the DMT-constrained modulus () for both natural and inundated conditions. The presented an average reduction of 56% from natural to inundated condition. This parameter can be used in a model to predict load-settlement curves by DMT data considering the suction influence on this behaviour. The curves obtained from the prediction model were compared to curves determined by PLT conducted under the same in situ conditions. Good agreement was found between the curves predicted by DMT and those measured by PLT for both conditions. The proposed procedure, which uses a device attached to the DMT blade, provides an investigation method to obtain the load-settlement curve under different suction conditions, which can help in the selection and performance prediction of shallow foundations, taking into account suction and collapse phenomenon-related problems.
平板载荷试验（PLT）是研究非饱和可缩性土中基础的荷载-沉降特性最可靠的现场测试方法。在这些土壤中，吸力剖面沿深度方向不是恒定的，原型和基础之间的比例效应导致不同的平均吸力，从而导致不同的数据。消除土壤吸力对试验数据影响的一种方法是在试验前将土壤充分饱和，这在设计可缩性土上的基础时也被推荐。然而，PLT 上的淹没过程昂贵且耗时，这使得该程序难以纳入工程实践。本研究提出了一种可附加到平板贯入仪（DMT）上的装置，允许对土壤进行局部淹没，作为原位试验的一部分，并获得自然和淹没条件下的 DMT 约束模量（）。结果表明，与自然条件相比，淹没条件下的平均降低了 56%。该参数可用于模型中，通过 DMT 数据预测考虑吸力对这种行为的影响的荷载-沉降曲线。由预测模型得到的曲线与在相同原位条件下进行的 PLT 得到的曲线进行了比较。对于两种情况，都发现由 DMT 预测的曲线与由 PLT 测量的曲线之间存在良好的一致性。该方法使用附加在 DMT 叶片上的装置，提供了一种在不同吸力条件下获得荷载-沉降曲线的研究方法，可以帮助选择和预测浅基础的性能，同时考虑吸力和坍塌现象相关问题。
