【作者】 王东；

【导师】 康天合；

【作者基本信息】 太原理工大学 ， 采矿工程， 2010， 博士

【摘要】 物化型软岩是指含有大量黏土矿物,在工程扰动下易于发生失水-吸水产生胀缩性和工程特性持续降低的软弱岩体,它是矿业工程、岩土工程、水电工程、地下储库等领域经常涉及到的重大岩石力学问题之一。常用的软岩与软岩工程控制方法为锚喷与注浆加固、强力棚式支护、砌碹或封闭混凝土反拱等,这些方法均是从力的平衡角度来考虑,没有从改变软岩自身的物理、化学特性和力学特性的角度来考虑。为此,本文提出了采用电化学固结改性技术改变有代表性软岩的矿物成分和组织结构,实现软岩与软岩工程长期稳定性的研究方法,为软岩工程灾害的控制提供卓有成效理论依据和技术支持,对减少和防止软岩工程灾害的发生具有十分重要的科学意义和广泛的应用价值。针对物化型软岩的晶层结构和阳离子交换能力,本文分别选取蒙脱石含量为主的软岩(蒙脱石软岩)和伊利石含量为主的软岩(伊利石软岩)作为研究对象,根据物化型软岩电化学固结改性过程中的双电层理论,理论分析物化型软岩电化学固结改性过程中的电化学机理;分析蒙脱石软岩和电化学改性相关的矿物学性质,主要为带电性、电荷来源、电荷种类、双电层、pH值、零净电荷点、永久电荷密度、比表面积、孔容和孔径等;分析蒙脱石软岩在电化学改性过程中的矿物成分和晶层结构的变化规律;分析电化学作用对蒙脱石软岩颗粒物沉降与体积膨胀性的影响;分析电化学作用对伊利石软岩孔隙结构和力学特性的影响。以下为本文的主要研究成果:1、总结出黏土矿物和软岩在电化学固结改性过程中的电化学机理,即黏土矿物和软岩的电渗现象、电泳现象和电解现象等电化学现象。在电化学作用下,软岩的矿物成分会发生改变并生成新的矿物,电渗脱水固结使软岩的物理力学特性发生变化。2、使用X-射线衍射、X-射线荧光光谱、快速电位滴定、电泳和氮气物理吸附等方法对物化型软岩的阳离子类型、零净电荷点、永久电荷密度、ζ电位、等电点、比表面积、孔容-孔径分布等矿物学参数在电化学改性前后进行了系统分析研究。3、在不同CaCl2电解液浓度和不同电位梯度条件下,电化学作用能够改变软岩的矿物成分,软岩中蒙脱石的含量降低且生成新的矿物,新生矿物为方解石、三水铝石、硬石膏和水铝英石。电化学作用后软岩阳极和中间区域的蒙脱石含量降低较小,阴极区域的蒙脱石含量降低较大。电化学作用后软岩中蒙脱石晶层结构的层间距和平均晶粒大小均发生了变化,软岩各区域层间距均呈指数规律递增。在不同CaCl2电解液浓度条件下,软岩阳极和中间区域蒙脱石的平均晶粒大小随电解液浓度的增加呈指数规律变化,阴极区域蒙脱石的平均晶粒大小随电解液浓度的增加呈高斯规律变化;在不同电位梯度条件下,软岩各区域蒙脱石的平均晶粒大小均随电位梯度的增加呈高斯规律变化。4、蒙脱石软岩颗粒物在蒸馏水中的沉降过程为缓慢润湿、加速沉降和体积稳定等3个阶段。电化学作用能够加速颗粒物的沉降速度,但不能改变岩样颗粒物沉降稳定后的体积膨胀特性。5、使用Matlab对CT单张图像进行数字图像处理,生成CT图像序列,使用可视化重构算法中的体绘制算法对其进行三维重构,生成岩石的二值化三维数字图像。根据岩石的二值化三维数字图像就可以计算出岩石的孔隙率;对岩石的CT单张图像进行压缩,再进行数字图像处理和三维重构,生成不同分辨率的岩石二值化三维数字图像,可以确定基于CT图像序列岩石的孔隙率随孔隙孔径的变化规律。电化学作用能够提高泥岩自身的力学特性,伊利石软岩原岩样的平均抗拉强度为1.31MPa,浸入蒸馏水中平均抗拉强度为0.81MPa;电化学改性后,平均抗拉强度均提高,提高了16.79%～116.03%。在泥岩的阳极区域,电化学改性后泥岩的孔隙率小于改性前的孔隙率;在泥岩的阴极区域,电化学改性后泥岩的孔隙率大于改性前的孔隙率。更多还原

【Abstract】 The physicochemical soft rock is a kind of rock in which containing a great amount of clay minerals. Under engineering disturbance conditions, it is easy to produce swell and shrink by wetting and drying and to reduce rapidly its engineering properties. It is one of the biggest rock mechanics problems in geotechnical engineering. It is usually controlling methods about soft rock engineering that bolting and shotcreting, grouting reinforcement, strengthening rack supporting, arching and close concrete camber. These methods all base on equilibrium of forces and not base on its physical, chemical and mechanical properties. In the paper electrochemical modified method is introduced, which can change mineralogical composition, crystal structure, the pore stuctue, and control the stability of soft rock engineering. The method can provide the theoretical reference and technical supporting for the controlling of the disaster of soft rock engineering, and has significant scientific value and extensive application value for decreasing and preventing the disaster of soft rock engineering.According to the crystal structure and anodic exchange capacity, the montmorillonitic soft rock and illitic soft rock are taken as the researth object. Based on the theory of electric double layer in the electrochemical treatment, the electrochemical modified mechanism of the physicochemical soft rock was theoretical analyzed; the mineral properties of montmorillonitic soft rock related to the electrochemical modification was experimental analyzed, which main including in charge property, electric double layer, the pH value, the point of zero charge(pHZPNC), the permanent charge density(σP), the specific surface area, porosity and pore aperture; the change rule of mineralogical composition and crystal structure of montmorillonitic soft rock was analyzed; the effect on subsidence and expandability of montmorillonitic soft rock particles was studied; and the modification about the pore structure and mechanical property of illitic soft rock was analyzed. The following is main research results:1. The electrochemical modified mechanism about clay minerals and soft rock in electrochemical modification was summarized, which is the electrochmical phenomenon of clay mineral and soft rock, such as electroosmosis, electrophoresis, and electrolysis. Under the electrochemical treatment, the mineralogical composition of soft rock will alert and generate new minerals, and change the physical and mechanical properties by electroosmotic drainage.2. The mineral parameters of the physicochemical soft rock which including in cation types, pHZPNC,σP, theζpotential, the isoelectric point, the specific surface area, the pore volume–diameter distribution, et al. was analyzed systemically by X-ray diffraction, X-ray fluorescence spectral analysis, potentiometric titration, electrophoresis, and nitrogen adsorption isotherm under modified and unmodified conditions.3. With different CaCl2 electrolyte concentration and different electric gradient, the mineralogical composition of soft rock is altered; the newly formed minerals are calcite, gibbsite, anhydrite and allophane. The montmorillonitic content in the anodic, cathodic and intermediate zones of soft rock decreases under electrochemical treatment. The electrochemical modification can result in a change of montmorillonitic crystal structure in soft rock also, and the crystallographic planes in all zones exponent increases. Under different CaCl2 electrolyte concentration, with increasing the concentration, the crystalline size in anodic and intermediate zones change by exponent rule, and the size in cathodic zone change by Gauss rule. Under different electric gradient, with increasing the electric gradient, the crystalline sizes in all zones change by Gauss rule.4. The subsidence process of montmorillonitic soft rock particles is wetting slowly, subsiding accelerately, and volume steady. The treatment of electrochemical modification can change subsidence rate of soft rock particles in distilled water and not affect its volume expandability when the subsidence is in stable state.5. The combination of micro-CT, digital image processing and three-dimensional reconstruction can provide a new, simple and feasible method for the analysis of rock pore structure. The single digital image is processed by image segmentation, binarization and compression, and the new images with different resolutions are generated. When the pixel size of the new image is taken as the pore aperture, the rule of the rock porosity variation with the pore aperture is estimated from Micro-CT single image. The volume rendering algorithm of visualized reconstruction can make the single image become the image sequence, and generate three-dimensional digital image. The rule of the rock porosity variation with the pore aperture is estimated on the base of the image sequence. Electrochemical modification can increase the mechanical property of soft rock. The mean tensile strength of the original sample is 1.31MPa; after merging in distilled water it changes to 0.81MPa, and with electrochemical modification it will increase by 16.79%-116.03%.更多还原