| 微生物砂浆防护粉土坡面的强度与抗侵蚀性影响因素分析 |
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| 引用本文： | 邵光辉,冯建挺,赵志峰,刘鹏,李泽,周宁娜.微生物砂浆防护粉土坡面的强度与抗侵蚀性影响因素分析[J].农业工程学报,2017,33(11):133-139. |
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| 作者姓名： | 邵光辉 冯建挺 赵志峰 刘鹏 李泽 周宁娜 |
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| 作者单位： | 1. 南京林业大学土木工程学院,南京 210037;江苏省水土保持与生态修复重点实验室,南京 210037;2. 南京林业大学土木工程学院,南京,210037 |
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| 基金项目： | 国家自然科学基金项目(51578293)；江苏高校优势学科建设工程资助项目(PAPD2015)；国家大学生实践创新训练计划项目(201510298005Z) |
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| 摘 要： | 微生物砂浆表面防护处理是处理粉土边坡扬尘与水流侵蚀问题的新技术。采用微生物砂浆层对粉土表面进行防护处理试验,通过微型贯入试验、水稳定性试验以及模拟降雨冲刷试验,分析了微生物砂浆防护层厚度、CaCl_2和尿素混合胶结溶液浓度、喷洒处理遍数等参数变化对微生物砂浆表面防护层的强度、水稳定性和土壤剥蚀率等性能的影响规律。结果表明,微型贯入仪可用于微生物砂浆表面防护层的强度测定,防护层的强度、水稳定性随胶结溶液浓度和喷洒处理遍数的增长而提高,最小有效厚度为5 mm。采用浓度为0.50 mol/L胶结溶液喷洒4遍,厚5 mm的防护层能够达到贯入阻力310 kPa,防护强度比77.5,崩解率2.3%,浸水强度损失率5.4%,具备较高的强度和较好的抗崩解性与强度水稳定性。粉土边坡在微生物砂浆防护前后,土壤剥蚀率能够从大于29.6降至6.8 g/(m~2·s)以下。该研究表明,微生物砂浆层用于粉土表面防护具有较好的抗冲刷性;微生物诱导结晶的方解石形成包裹砂颗粒的胶结微结构,能够使表面防护砂浆层具备良好的抗水流侵蚀性。
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| 关 键 词： | 粉土 侵蚀 砂浆 诱导碳酸钙沉积 水稳定性 土壤剥蚀率 防护工程 |
| 收稿时间： | 2016/12/9 0:00:00 |
| 修稿时间： | 2017/4/20 0:00:00 |
Influence factor analysis related to strength and anti-erosion stability of silt slope with microbial mortar protective covering |
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| Shao Guanghui,Feng Jianting,Zhao Zhifeng,Liu Peng,Li Ze and Zhou Ningna.Influence factor analysis related to strength and anti-erosion stability of silt slope with microbial mortar protective covering[J].Transactions of the Chinese Society of Agricultural Engineering,2017,33(11):133-139. |
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| Authors: | Shao Guanghui Feng Jianting Zhao Zhifeng Liu Peng Li Ze and Zhou Ningna |
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| Institution: | 1. School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China; 2. Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration, Nanjing 210037, China;,1. School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China;,1. School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China; 2. Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration, Nanjing 210037, China;,1. School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China; 2. Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration, Nanjing 210037, China;,1. School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China; and 1. School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China; |
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| Abstract: | Microbial mortar protective covering is a new technology for controlling silt slope surface dust and water erosion. The anti-erosion performance of the protective covering depends to a large extent on the strength and stability of covering. However, the factors that govern the protective property of covering have not been fully studied. Based on microbial induced calcite precipitation (MICP) technology, the surface protective covering experiments were carried out to treat silt slope surface against rainfall erosion. Indoor model tests on silt surface protective covering by microbial mortar were performed to investigate the properties such as strength, water stability and anti-erosion. Sand was covered on dredger fill silt surface to form a thin layer, and then some Sporosarcina pasteurii and a kind of cementing solution containing a mixture of CaCl2 and urea were sprayed on the sand layer surface to obtain a crustose protective covering. The micro-penetration test was adopted to investigate the penetration resistances change of uncovered silt and protected silt covered with microbial mortar crust. The property of protective strength ratio measured by micro-penetration test was used to evaluate the strength of microbial mortar protective covering relative to uncovered silt surface. The collapse ratio and strength loss ratio were tested on the microbial mortar protective covering by immersed in water for 12 h to assess its water stability performance. The change laws of protective covering strength and water stability were drawn from different covering thickness, mixed cementing solution concentration of CaCl2 and urea, and spraying times. On the basis of the tests of protective covering, the rainfall model experiments were conducted. A slope angle variable steel tank with the size of 1.4 m × 0.3 m× 0.06 m (length × width × height) was applied for holding test material and simulating the silt slope, which was subjected to strong rainfall scour under a rainfall simulating system. The soil detachment rates were investigated from the rainfall simulation experiment by changing slope angle from 5o to 25o and rainfall time from 4 to 20 min. The experimental results revealed that: 1) The minimum effective thickness of microbial mortar protective covering was 5 mm. The strength and water stability of protective covering increased with the cementing solution concentration, protective covering thickness and spraying times. 2) After treated 4 times with 0.50 mol/L cementing solution, a protective covering was formed, which had high strength, good anti-collapse property and excellent water stability. A 5 mm thick protective covering could reach penetration resistance of 310 kPa, protective strength ratio of 77.5, collapse ratio of 2.3%, and strength loss ratio of 5.4% when immersed in water. 3) Compared with untreated silt slope, the treated silt slope reduced soil detachment rate from over 29.6 g/(m2·s) to under 6.8 g/(m2·s). The soil detachment rate of treated silt slope was between 5.4 and 6.8 g/(m2·s) and insensitive to the slope angle. Under 20 min heavy rainfall scouring, the soil detachment rate of treated silt slope was only 3.6 g/(m2·s). The microbial mortar protective covering presented significant anti-erosion capacity. 4) The strength of protective covering and the permeability of substratum silt had coupling effect on the anti-erosion mechanism of microbial mortar protective covering. The coarse and porous covering played an important role in resisting raindrop splash and surface flow erosion by the high strength of crust. Meanwhile, the low permeability of silt under the covering resisted piping and suffusion erosion. The anti-erosion effectiveness of protective covering was dominated by the microbial mortar crust strength. For effective microbial mortar protection, at the microstructure level it was essential that the cement calcite from MICP formed surrounding cementation structure around soil particles surface. The results provide valuable information for applying MICP technology on silt slope anti-erosion. |
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| Keywords: | silt erosion mortar MICP water stability soil detachment rate protective engineering |
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