Prevention of soil compaction requires examining soil mechanical stability. This is usually done by applying the basic concept of the pre-compression stress σ_p, assuming a fully elastic behavior for soils being loaded by stresses lower than σ_p and a mixture of elastic-plastic behavior being loaded by higher stresses. However, a small cumulative plastic deformation may occur even when the applied stresses is not beyond σ_p being indeterminable by current pe-compression test procedures which is not accounting for unloading steps. Therefore, we investigated an alternative approach to simultaneously determine σ_p and mechanical elasticity of soil by introducing unloading steps (referred to as release compression, RC). Results were compared to the conventional procedure with continuously increasing loads (continuous compression, CC). In the case of RC, soil settlement was measured both after each loading (RC-L) and after each unloading (RC-U) phases between two consecutive pressures providing two load displacement curves. Oedometer tests were conducted with three different soils comprising different clay contents ranging from 75 to 454 g kg⁻¹. Remolded soil was filled into steel rings and compressed under pre-determined loads in a loading frame providing test samples with known pre-compression stresses of 60 and 120 kPa. The results revealed that σ_p values determined under two different applied loading paths (RC vs. CC) were significantly different. Both testing approaches resulted in an overestimation of σ_p values based on stress-strain curves which was more pronounced for RC-L compared to CC paths. However, the results from RC-U paths were closer to the CC method than the RC-L path suggesting that if an unloading step is used, RC-U curve should be used to determine σ_p values. The results also showed that soil with higher clay contents comprised the lowest σ_p value determined from the oedometer tests among all examined soils. From release compression test, we were also able to determine the elasticity of the sample for each loading stress. Among the examined soil samples, the clay soil (with higher clay content) showed the highest elasticity index being less susceptible to soil deformation.

防止土壤板结需要检查土壤的机械稳定性。这通常是通过应用预压应力σ _p的基本概念来完成的，假设土壤在低于σ _p的应力下具有完全弹性行为，而在较高应力下是弹塑性行为的混合物。然而，即使施加的应力不超过σ _p ，也可能会发生小的累积塑性变形，而当前的 pe 压缩测试程序无法确定卸载步骤。因此，我们研究了一种同时确定σ _p的替代方法和通过引入卸载步骤（称为释放压缩，RC）的土壤的机械弹性。将结果与连续增加载荷（连续压缩，CC）的传统程序进行比较。在 RC 的情况下，在每次加载 (RC-L) 和每次卸载 (RC-U) 阶段之后，在两个连续压力之间测量土壤沉降，从而提供两条载荷位移曲线。Oedometer 测试用三种不同的土壤进行，包括从 75 到 454 g kg ^-1的不同粘土含量。将改造后的土壤填充到钢环中，并在预先确定的载荷下在加载框架中进行压缩，从而为测试样品提供 60 和 120 kPa 的已知预压缩应力。结果表明，σ _p在两种不同的应用加载路径（RC 与 CC）下确定的值显着不同。两种测试方法都导致了基于应力-应变曲线的_σp值的高估，与 CC 路径相比，RC-L 更明显。然而，RC-U 路径的结果比 RC-L 路径更接近 CC 方法，这表明如果使用卸载步骤，则应使用 RC-U 曲线来确定σ _p值。结果还表明，粘土含量较高的土壤包含最低的σ _p在所有被检查的土壤中，由 oedometer 测试确定的值。通过释放压缩测试，我们还能够确定每个加载应力下样品的弹性。在检查的土壤样品中，粘土（粘土含量较高）显示出最高的弹性指数，不易受土壤变形的影响。