Peat ground is widely spread throughout the Halfaya oilfield in Al-Amara city, southern Iraq. Peat includes a large quantity of organic matter and has a very high natural water content. Its unsuitability as a foundation material has brought about serious problems for construction works. In the present study, the multistage oedometer relaxation test was developed to measure the vertical stress, lateral stress, and pore water pressure with time and estimate the coefficient of lateral earth pressure in the soil. A new factor for relaxation in organic soil is suggested. The test consists of six stages; each stage is 10–30 min long, except if pore water pressure is not dissipated. Results of long-term stress relaxation revealed that after a definite time, a linear relationship exists between the increase in relaxation of stress and the logarithm of time. This means that stress relaxation continues and will never stop. Low applied stresses result in high values of relaxation factor for different soil samples, but after the stress of 300 kPa, all samples revealed the same value of the relaxation factor.

泥炭地广泛分布在伊拉克南部阿尔阿马拉市的哈法亚油田。泥炭含有大量有机物，天然含水量非常高。它不适合作为地基材料给建筑工程带来了严重的问题。在本研究中，开发了多级固结仪松弛试验，以测量随时间变化的垂直应力、侧向应力和孔隙水压力，并估算土壤中的侧向土压力系数。提出了一种新的有机土壤松弛因素。测试包括六个阶段；每个阶段长 10-30 分钟，除非孔隙水压力没有消散。长期应力松弛结果表明，经过一定时间后，应力松弛的增加与时间的对数之间存在线性关系。这意味着压力放松会继续并且永远不会停止。施加的低应力导致不同土壤样品的松弛因子值较高，但在 300 kPa 应力后，所有样品显示相同的松弛因子值。