单向压缩状态下滇池泥炭土的蠕变特性研究

为探究不同埋深和扰动状态对滇池泥炭土固结蠕变特性的影响,采用分级加载方式分别对埋深17 m、34 m的原状和扰动泥炭土样进行了一维固结蠕变试验。结果表明:泥炭土粘塑性蠕变特性显著,扰动后竖向应变在各级压力下均较高。17 m土样前期固结压力较小,孔隙和有机质较多,压缩性更高。土体内排水通道随固结压力增大被逐渐压缩,延长了主固结时间。扰动土因结构性被破坏,主固结时间较短。17 m原状土的固结系数在低固结压力下较大,其结构随压力增加而破坏,固结系数逐渐接近于扰动样;34 m土样分解度高且较密实,扰动后易于排水,故扰动土固结系数大于原状土。滇池泥炭土的次固结系数大于一般软粘土,且有机质含量较高的17 m土层的次固结特性更为显著。

Study on Consolidation Creep Properties of Dianchi Peaty Soil under One-dimensional Compression

To study the effects of different depths and disturbed states on the consolidation creep properties of Dianchi peaty soil, the step loading is applied to carry out the one-dimensional consolidation creep test for the undisturbed and disturbed peaty soil, which is collected at 17 m and 34 m depths, respectively. The results show that the peaty soil exhibits obvious viscoplastic creep properties. Compared with the undisturbed one, the disturbed peaty soil has the lager vertical strain. The peaty soil with the depth of 17 m shows the higher compressibility, which is attributed to its smaller pre-consolidation pressure, larger voids and more organic fiber components. With the increase of consolidation pressure, the drainage channel is compressed gradually, which extends the primary consolidation time of peaty soil. The structure of disturbed soil is destroyed, which induces that the pore pressure dissipates faster and the primary consolidation time less than that of the undisturbed one. Under the lower consolidation pressure, the consolidation coefficient of undisturbed soil at 17 m is lower than that of the disturbed one. As the increase of consolidation pressure, soil is destroyed generally, and their consolidation coefficients tended to be similar. The peaty soil at 34 m has the higher decomposition degree of organic matter and denser structure, the structure becomes loose and favorable for drainage after disturbed, thus the consolidation coefficient of disturbed soil is greater than that of the undisturbed one. The secondary consolidation coefficient of peaty soil is much larger than that of the general soft soil. The organic fiber composition is higher for the peaty soil with the depth of 17 m, and its secondary consolidation properties are more prominent.