كليدواژه :
سيمانتاسيون بيولوژيكي , غلظت نزولي , غلظت ثابت , سه‌محوري , باسيلوس پاستوري
چكيده فارسي :
روش سيمانتاسيون بيولوژيكي، روشي نوين براي اصلاح خاك بر مبناي رسوب كلسيم‌كربنات است. تا به امروز پژوهش‌هاي بسياري در مورد آن صورت گرفته است كه در آن‌ها توجه كمتري به تأثير تزريق نزولي در شكل‌گيري بلورهاي كلسيت در سيمانتاسيون بيولوژيكي خاك‌هاي ماسه‌يي شده است. در پژوهش حاضر، از باكتري حاوي اسپور استفاده شده است تا به كمك آن، تأثير مولاريته و نوع تزريق (ثابت و نزولي) در مقاومت و نفوذپذيري خاك بررسي شود. لذا نمونه‌هاي سيمانته شده، تحت آزمايش‌هاي سه‌محوري، نفوذپذيري و SEM قرار گرفتند تا با استفاده از نتايج حاصل، به بررسي مورد اخير پرداخته شود. نتايج نشان مي‌دهند كه نمونه‌ي سيمانته شده با غلظت ثابت 1/5 مولار، بهترين عملكرد را داشته و در تنش بيشينه‌ي 1519 كيلوپاسكال نسبت به ماسه‌ي تميز، %61/08 افزايش مقاومت داشته است. همچنين ضريب نفوذپذيري نمونه‌ي سيمانته شده با غلظت ثابت 1/5 مولار برابر 0/047 سانتي‌متر بر ثانيه بوده است كه افزايش %41/25 نسبت به ماسه‌ي تميز را نشان مي‌دهد.
چكيده لاتين :
Rapid population growth and wave of immigration to cities are growing needs to expand construction in cities. So, reinforcement of bed soil has a high importance in urban structures. The soil must be stabilized for various applications such as: decrease in erodibility, increase in loading capacity and increase in compressive strength. At the ground level, soil can be stabilized by ecological and compaction methods but in depth, improvement should be done by infusion. Injection of chemical substances is costly, destructive and it causes the destruction of the hydrological ecosystem of the improved area, in addition to, ground water may be deviated from their path. Biological cementation is a modern and environmentally-friendly method to remedy the soil that it has been developed through the linkage of civil, geochemical and microbiological fields. This method of improvement is based on Microbial Induced Calcite Precipitation sedimentation, so sedimentary bacteria is used. To date, many studies have been conducted in which less attention has been paid to the effect of descending injection on the formation of calcite crystals in the biological cementation of sandy soils. Therefore, in the present study, a type of bacterium containing spore called Bacillus pasteurii was used to help the effect of molarity as well as The type of injection (constant and descending) on soil strength and permeability should be investigated. For this purpose, biologically cemented specimens by this method were tested in tri-axial consolidated undrained test, fixed load permeability and scanning electron microscope to investigate this case using the results to be proceeded. The results show that as the concentration increases, more calcite is formed in the soil, therefore the cemented sample with a constant concentration of molar had the best performance and compared to untreated sand, % an increase of resistance and % a decrease of permeability was observed.
