Compaction of water-saturated soil by surface vacuuming

The results of laboratory studies of compaction of weak water-saturated soils using surface vacuuming are presented. Experiments on the compaction of water-saturated peat by the method of surface vacuuming under the screens were carried out on a special installation. The vacuum was created under round sealed screens of different sizes and stiffness. As the results of the experiments showed, the mechanism of compaction of weak water-saturated soils during vacuuming from the surface under the protection of a sealed coating is determined by the action of volumetric filtration forces. When vacuuming, in contrast to the compaction load, there is no soil venting around the perimeter of the compacted surface area, which significantly increases the efficiency of this method. And the use of flexible screens (geo-membrane) opens up opportunities for construction. A series of compression tests was carried out to identify the similarities and differences in the consolidation processes when compacting different materials by vacuuming and equivalent load created by the press.

Orthogonal Analysis on the Remediation of Diesel Contaminated Soil by Enhancing Bioventing

Bioventing is an in situ forced oxidative soil remediation technology which combined soil vapor extraction with biodegradation. It has broad application prospects of soil contamination caused by underground storage tank leakage. Orthogonal experiment as a high efficiency, rapid and economical experimental design method has been widely used in many research. In order to enhance bioventing and shorten the cycle of pollution control,it is necessary to study the mechanism of the interaction among the different factors to quantify the interaction and accelerate the degradation rate. In this study, five factors (initial diesel concentration, venting mode, pore volume number during soil venting, soil moisture content and the ratio of carbon, nitrogen and phosphate) which influence bioventing was chosen to conduct orthogonal experiment of the remediation of diesel contaminated soil by enhancing bioventing. The results show that: 1)Initial diesel concentration and soil moisture content have main effects on the remediation of diesel contaminated soil by bioventing, then the ratio of carbon, nitrogen and phosphate and pore volume number during soil venting. Venting mode has the weakest effect. 2)When 40mg oil/g soil of diesel concentration, air injecting from the bottom of column, 4 vk·d-1 of the pore volume number during soil venting, 100:20:1 of the ratio of carbon, nitrogen and phosphate and soil water content for 20% of the maximum of soil water holding capacity, that would reach a larger removal rate.