【摘要】：傳統(tǒng)土壤改良固化劑或灌漿材料多含有有毒物質(zhì)。我國工程建筑過程中對其的使用會加重環(huán)境污染程度,因此研究新型環(huán)境友好的土壤加固技術具有重要的現(xiàn)實意義。微生物誘導碳酸鹽沉淀(Microbial Induced Calcite Precipitation,以下簡稱MICP)作為自然界廣泛存在的一種生物誘導礦化現(xiàn)象,其具有機理簡單,快速高效,容易控制,環(huán)境耐受性好等很多傳統(tǒng)方法無法比擬的優(yōu)勢。該技術用于土壤加固,將會帶來巨大的環(huán)境效益和經(jīng)濟效益。基于MICP法,本文主要以巴氏生孢八疊球菌(Sporosarcina pasteurii)膠結標準砂。試驗過程中開展了微生物活化培養(yǎng)保存、X衍射、電鏡掃描、固結排水剪切、無側(cè)限抗壓剪切及碳酸鈣含量化學試驗等一系列室內(nèi)試驗,主要研究了營養(yǎng)鹽溶液濃度、處理方式以及培養(yǎng)溫度對MICP膠結試樣物理力學特性的影響,為MICP固化土壤的實際應用提供基礎數(shù)據(jù)。本文的主要研究成果為:(1)營養(yǎng)鹽溶液濃度的變化對微生物膠結砂土的物理力學特性有極大的影響。在同等營養(yǎng)鹽溶液注液量和反應時間下,膠結試樣強度隨著營養(yǎng)鹽溶液濃度的增加,表現(xiàn)為先增后減趨勢——呈凸字形態(tài)。(2)MICP膠結試樣固結排水剪切均表現(xiàn)為應力軟化形態(tài),試驗結果表明碳酸鈣的沉積對砂樣的剪脹性具有抑制作用。同時彈性模量隨著MICP膠結試樣干密度的增加而增加。(3)營養(yǎng)鹽溶液濃度影響試驗中,0.5M膠結試樣c′、φ′值最大膠結效果最優(yōu),依據(jù)試驗結果及前人研究結論,分析是由于其良好碳酸鈣的分布形態(tài)以及較高碳酸鈣晶體的沉積量。(4)采用高/低濃度營養(yǎng)鹽溶液相結合的處理方式膠結標準砂。膠結試樣可在較短時間表現(xiàn)較高的強度、碳酸鈣含量以及較好的均勻性,較為適用膠結深度淺且強度要求較高的土體,具有較好的工程應用潛力。(5)培養(yǎng)環(huán)境溫度影響試驗結果表明:膠結試樣在溫度為20℃、30℃、40℃環(huán)境下培養(yǎng)時,其碳酸鈣含量相差不大;但溫度的變化對試樣強度及變形模量影響較為明顯,隨著溫度的升高(20-40℃)微生物膠結試樣的強度及變形模量表現(xiàn)為先增后減的趨勢。依據(jù)試驗結果分析是由于溫度變化致使碳酸鈣沉積不同晶型造成膠結效果的差異。
[Abstract]:Traditional soil improvement curing agents or grouting materials contain toxic substances. The use of engineering buildings in China will aggravate the degree of environmental pollution, so it is of great practical significance to study the new environmentally friendly soil reinforcement technology. Microbial induced carbonate precipitation (Microbial Induced Calcite Precipitation,) is a kind of biologically induced mineralization phenomenon which exists widely in nature. Its mechanism is simple, fast and efficient, and it is easy to control. Environmental tolerance and many other traditional methods can not be compared with the advantages. The application of this technology to soil reinforcement will bring great environmental and economic benefits. Based on MICP method, (Sporosarcina pasteurii) cementing standard sand was mainly used in this paper. During the experiment, a series of laboratory experiments were carried out, such as microorganism activation culture preservation, X-ray diffraction, electron microscope scanning, consolidated drainage shear, unconfined compressive shear and calcium carbonate content chemical test, etc. The concentration of nutrient solution was studied. The effects of treatment methods and culture temperature on the physical and mechanical properties of MICP cemented samples provide basic data for the practical application of MICP solidified soil. The main results of this paper are as follows: (1) the change of nutrient solution concentration has great influence on the physical and mechanical properties of microbial cemented sand. Under the same amount of liquid injection and reaction time, the strength of the cemented sample increases with the concentration of the nutrient solution. (2) the consolidation and drainage shear of MICP cemented specimens showed stress softening. The results showed that the deposition of calcium carbonate could inhibit the shear dilatancy of sand samples. At the same time, the modulus of elasticity increases with the increase of dry density of MICP cemented sample. (3) in the experiment of the effect of concentration of nutrient salt solution, the maximum cementing effect of 0.5M cemented sample is the best. According to the test results and previous research conclusions, The analysis is due to the good distribution of calcium carbonate and the high deposition amount of calcium carbonate crystal. (4) the standard sand is cemented by the combination of high / low concentration nutrient solution. The cemented specimen can show higher strength, calcium carbonate content and better homogeneity in a short time, which is more suitable for soil with shallow cementing depth and high strength. (5) the effect of culture environment temperature on the content of calcium carbonate is not significant when the temperature is 20 鈩，

本文編號：2402734