營養(yǎng)鹽濃度對膠結(jié)重塑泥巖試樣力學(xué)特性及微觀結(jié)構(gòu)的影響試驗(yàn)研究

王緒民 崔芮 王鋮

摘要：采用一次浸泡菌液的方式，制備不同濃度（0、0.3、0.5、0.7 mol/L）營養(yǎng)鹽處理的微生物誘導(dǎo)碳酸鈣沉淀（MICP）膠結(jié)重塑泥巖樣。基于直接剪切、碳酸鈣酸洗法、掃描電鏡（SEM）等試驗(yàn)測試膠結(jié)試樣，分析了營養(yǎng)鹽濃度對膠結(jié)試樣力學(xué)性能、碳酸鈣含量及微觀結(jié)構(gòu)的影響。結(jié)果表明：同等反應(yīng)條件下（相同時(shí)間、體積），隨著營養(yǎng)鹽濃度的增加抗剪強(qiáng)度先增大后減小，當(dāng)營養(yǎng)鹽濃度達(dá)到0.5 mol/L時(shí)抗剪強(qiáng)度最大，此時(shí)，試樣黏聚力、內(nèi)摩擦角分別為15.5 kPa、18.83°;碳酸鈣含量隨著營養(yǎng)鹽濃度的增加而增加，當(dāng)營養(yǎng)鹽濃度達(dá)到0.7 mol/L時(shí)，試樣平均碳酸鈣含量提高較少;碳酸鈣晶體分布均勻性隨著營養(yǎng)鹽濃度由低到高變化呈凸字形態(tài);膠結(jié)試樣的強(qiáng)度依賴于生成的CaCO3晶體量及其分布形態(tài);生成的方解石型碳酸鈣晶體主要沉積在顆粒接觸處形成積聚晶體或填充在孔隙中形成“膠結(jié)橋”，產(chǎn)生膠結(jié)效果而增強(qiáng)試樣的力學(xué)性能。

關(guān)鍵詞：微生物誘導(dǎo)碳酸鈣沉淀;重塑泥巖;物理力學(xué)指標(biāo);營養(yǎng)鹽;微觀結(jié)構(gòu)

中圖分類號(hào)：TU411.3;TU411.92 文獻(xiàn)標(biāo)志碼：A 文章編號(hào)：20966717（2020）04007608

收稿日期：20191113

基金項(xiàng)目：湖北工業(yè)大學(xué)科研基金（BSQD14040）

作者簡介：王緒民（1972 ），男，博士，副教授，主要從事巖土工程膠結(jié)土力學(xué)特性研究，Email：wxumin@163.com。

Received：20191113

Foundation items：Research Fund of Hubei University of Technology （No. BSQD14040）

Author brief：Wang Xumin（1972 ）， PhD， associate professor， main research interest： soil mechanics characteristics of geotechnical engineering， Email： wxumin@163.com.

Experimental study on effect of nutrient concentration on mechanical properties and microstructure of cemented remolded mudstone

Wang Xumin， Cui Rui， Wang Cheng

（School of Civil Engineering & Environment， Hubei University of Technology， Wuhan 430068， P.R. China）

Abstract： Microbial induced calcium carbonate precipitation （MICP） cemented remolded mudstone samples were prepared by injecting onetime bacteria solution with different concentrations （0， 0.3， 0.5， 0.7 mol/L） of nutrient salt treatment. Based on the results of direct shear test， calcium carbonate pickling and scanning electron microscopy （SEM）， the effects of nutrient concentration on the mechanical properties， calcium carbonate content and microstructure of the cemented samples were analyzed. The results show that under the same reaction conditions （same time， volume）， the shear strength increase at first and then decrease with the increase of nutrient concentration. When the nutrient salt concentration reaches 0.5 mol/L， the shear strength reaches the largest value. At this time， the cohesive force and internal friction angle of the sample are 15.5 kPa and 18.83°， respectively. The content of calcium carbonate increase with nutrient concentration. When the concentration of nutrient salt reaches 0.7 mol/L， the average calcium carbonate content of the sample increases less. The uniformity of calcium carbonate crystal distribution changes in a convex shape with the increase of nutrient salt concentration from low to high. The strength of the cemented sample depends on the amount of CaCO3 crystals formed and their distribution. The produced calcitetype calcium carbonate crystals are mainly deposited at the contact position of the particles to form accumulated crystals or filled in the pores to form a “bonding bridge”， which produces a cementation effect and enhances the mechanical properties of the sample.

Keywords：microbial induced calcium carbonate precipitation（MICP）; reshaping mudstone; physicomechanical index; nutrient; micro structure

隨著人口增長和社會(huì)經(jīng)濟(jì)發(fā)展，民用基礎(chǔ)設(shè)施的需求急劇增加，然而，在新建建筑或公路地基施工過程中經(jīng)常會(huì)遇到穩(wěn)定性差的泥巖層。泥巖是一種典型的軟巖，具有組成成分復(fù)雜、孔隙較小等特性，由于環(huán)境因素影響（干濕循環(huán)、溫度等）易發(fā)生風(fēng)化、開裂、崩解、軟化、膨脹等變化，使巖土特性發(fā)生強(qiáng)烈變化，如日本大部分滑坡發(fā)生在沉積軟巖中，尤其是泥巖地層[1]?！?br>