【作者】 李晓强；

【导师】 杨双锁； 胡国伟；

【作者基本信息】 太原理工大学 ， 矿业工程（专业学位）， 2021， 硕士

【摘要】 含水粉细砂地层是地下工程施工中较难治理的地质条件之一,其含水量丰富,自稳性差,胶结强度低,如果施工过程中处理不当,极易造成涌水、溃砂等重大安全事故。粉细砂地层孔隙小,当采用注浆法对其进行加固时,要求所使用的浆液具有很强的渗透性,常用的水玻璃等化学浆液对此地层的加固效果很不理想。为能有效加固此类地层,急需开发高渗透性浆液,并对其注浆加固机理进行研究。基于此,本文以太原地铁2号线南中环街站的粉细砂地层为研究对象,采用丙烯酸酯浆液对该地层进行注浆加固,针对其适用性、加固机理等问题,综合利用理论分析和数值模拟计算,结合大型的模拟试验,对丙烯酸酯材料进行优化并对粉细砂地层注浆加固机理进行研究。主要研究内容与结论如下:(1)通过室内试验,分析丙烯酸酯浆液在粉细砂中渗透时不同的固化剂配比对浆液渗透扩散范围的影响。试验结果表明:配制的浆液中固化剂占比越高,则浆液凝胶时间越短,浆液的扩散范围越小,结石体强度越高;在满足工程加固需求的条件下能使浆液在粉细砂地层中渗透范围达到最大的凝胶时间为25 min。(2)开展了2因素5水平的全面试验,研究砂土含水率与砂浆比对试样抗压、抗拉强度的影响规律。结果表明:砂土含水率低于8%,砂浆比超过6:1这一临界值时,浆液在土体中基本无法凝胶;而砂浆比在4:1到6:1这一范围内时,试样抗压、抗拉强度随砂土含水率的增大而降低。通过拟合试验数据获得了试样抗压、抗拉强度与砂土含水率及砂浆比的定量关系。(3)通过显微镜观察不同含水率试样的细观结构,分析出砂土中水分对试样强度的影响形式可分为:1)结合水膜的润滑作用;2)自由水参与浆液的聚合反应,使凝胶体强度降低;3)残余水的汽-液两相转化,导致浆液凝胶时结构体内部留有孔隙,试样强度因此降低。(4)以南中环街站的粉细砂地层为研究对象进行建模,运用有限差分软件进行注浆数值模拟计算,获得了不同节点处的渗流速度动态变化特征,通过与劈裂注浆理论的对比验证,进一步揭示了丙烯酸酯浆液在粉细砂地层的扩散加固机理。(5)通过模拟注浆试验,对注浆结石体进行强度测试,得到注浆结石体强度分布规律为:模型箱边界处结石体强度高,非边界区域结石体强度相对较低。拟合出注浆结石体强度与浆液沿劈裂通道扩散范围和扩散深度的关系式符合Parabolic(抛物面)方程。并结合丙烯酸酯浆液的特性,分析出注浆结石体强度分布主要受不透水边界和重力的影响。更多还原

【Abstract】 The formation of water containing fine sand is one of the geological conditions which is difficult to be controlled in the construction of underground engineering.It has abundant water content,poor self-stability and low cement strength.If it is not handled properly during the construction,it is very easy to cause serious safety accidents such as water gushing and sand break.The pore of fine sand stratum is small.When grouting is used to reinforce it,the slurry used is required to have strong permeability.The common chemical slurry such as water glass is not ideal for the reinforcement effect of the stratum.In order to strengthen such stratum effectively,it is urgent to develop high permeability slurry and study its grouting reinforcement mechanism.Based on this,this paper took the silty sand stratum of the Nanzhonghuanjie Station of Taiyuan Metro Line 2 as the research object,and used acrylate slurry for grouting reinforcement of the stratum.Aiming at its applicability,reinforcement mechanism and other problems,this paper comprehensively used theoretical analysis and numerical simulation calculation,combined with large-scale simulation test,optimizes the acrylate material,and analyzed the grouting reinforcement mechanism of the silty sand stratum Research.The main research contents and conclusions were as follows:(1)Through laboratory tests,the influence of different curing agent ratio on the diffusion range of acrylate slurry in fine sand was analyzed.The experimental results showed that the higher proportion of curing agent in the slurry is,the shorter gel time is,the smaller diffusion range of the slurry is,and the higher strength of the stone body.Under the condition of meeting the engineering reinforcement requirement,the maximum penetration of the gel in the fine sand stratum is 25 min.(2)A comprehensive test with 2 factors and 5 levels was carried out to study the influence of sand moisture content and mortar ratio on compressive and tensile strength of samples.The results show that when the moisture content of sand is less than 8% and the mortar ratio exceeds 6:1,the slurry is basically unable to gel in the soil;when the mortar ratio is in the range of 4:1 to 6:1,the compressive strength and tensile strength of the sample decrease with the increase of soil moisture content.By fitting the test data,the quantitative relationship between the compressive and tensile strength of samples and the moisture content of sand and mortar ratio was obtained.(3)The microscopic structure of samples with different moisture content was observed by microscope.The influence of water on the strength of samples was analyzed.The results showed that: 1)Combined with the lubrication effect of water film.2)Free water was involved in the polymerization of slurry,so that the strength of gel decreased.3)The vapor-liquid two phase transformation of residual water resulted in pore structure in the structure,and the strength of samples decreased accordingly.(4)Taking the silty fine sand stratum of Nanzhonghuanjie station as the research object,the finite difference software was used for grouting numerical simulation calculation,and the dynamic change characteristics of seepage velocity at different nodes were obtained.By comparing with the splitting grouting theory,the diffusion reinforcement mechanism of acrylic ester slurry in silty fine sand stratum was further revealed.(5)Through the simulated grouting test,the strength of the grouting stone body was tested,and the distribution law of the grouting stone body strength was obtained as follows:the strength of the stone body at the boundary of the model box is high,and the strength of the stone body in other areas is relatively low.The relationship between the strength of grouting stone body and the diffusion range and depth of slurry along the splitting channel is fitted,which conforms to parabolic equation.Combined with the characteristics of acrylate slurry,the strength distribution of grouting stones is mainly affected by the impermeable boundary and gravity.更多还原