Comparative experimental investigation of chemical grouting into a fracture with flowing and static water

We present a series of experimental tests on chemical grouting into a fracture with flowing and static water,using a transparent fracture grouting experimental device.Variations of seepage pressure and grout propagation were compared in our investigation.The results show that flowing water results in drops of seepage pressure,development of penetration radii in the upstream side and drops of propagation area during the same period,compared with grouting in static water.The propagation area in static water is always round before grouts reach the joint boundaries.However,the propagation shape changes from round to an elliptic shape for grouting into a fracture with flowing water.A theoretical model for the grout penetration radius in a fracture considering flowing velocity was developed and validated by our experimental results.These results are helpful in improving understanding of fracture grouting mechanism and in guiding engineering practices.

Characteristics of water inflow and chemical grouting treatment of a Liu Yuanzi Coal Mine shaft in the Ordos Basin

During shaft constructing, a borehole water inflow of 30 m3/h was encountered in Liu Yuanzi Coal Mine in the southwestern Ordos Basin, whose aquifer is mainly cretaceous. On the basis of regional hydrogeological conditions, a mercury intrusion method and scanning electron microscope were used in this study. We conclude that the loose, porous and easily collapsible clay particles of the cretaceous aquifer rock mass were the major geological cause for water hazards during the construction of the shaft. We propose an approach of chemical grouting from the working surface and in the end succeeded in blocking the water.

Optimization of cement-based grouts using chemical additives

Grout injection is used for sealing or strengthening the ground in order to prevent water entrance or any failure after excavation.There are many methods of grouting.Permeation grouting is one of the most common types in which the grout material is injected to the pore spaces of the ground.In grouting operations,the grout quality is important to achieve the best results.There are four main characteristics for a grout mixture including bleeding,setting time,strength,and viscosity.In this paper,we try to build some efficient grouting mixtures with different water to cement ratios considering these characteristics.The ingredients of grout mixtures built in this study are cement,water,bentonite,and some chemical additives such as sodium silicate,sodium carbonate,and triethanolamine(TEA).The grout mixtures are prepared for both of the sealing and strengthening purposes for a structural project.Effect of each abovementioned ingredient is profoundly investigated.Since each ingredient may have positive or negative aspect,an optimization of appropriate amount of each ingredient is determined.The optimization is based on 200 grout mixture samples with different percentages of ingredients.Finally,some of these grout mixtures are chosen for the introduced project.It should be mentioned that grouting operations depend on various factors such as pressure of injection,ground structure and grain size of soils.However,quality of a grout can be helpful to make an injection easier and reasonable.For example,during the injection,a wrong estimated setting time can destroy the injected grout by washing the grout or setting early which prevents grouting.This paper tries to show some tests in easy way to achieve a desirable sample of grout.

Chemical grout diffusion in porous rock based on response of geoelectric feld

Porous rock chemical grouting simulation test was conducted using established large scale physical model.Chemical grout diffusing rule in porous media with different permeability was studied by monitoring the spontaneous potential and exciting current response during grouting.The results show that chemical grout spread evenly in all directions and diffusion areas are approximately concentric circles in the cross section of homogeneous transverse isotropic pore medium,the grout spread flling range can be quantitatively decrypted by the diffusion radius.The average diffusion speed and radius increase approximately as the square root with the permeability coeffcient in different permeability media under the same conditions.Calculation results using Maag cylindrical diffusion equation show that the calculated value of diffusion radius is in good agreement with the test value under different grouting pressures and permeability conditions.

Strength of copolymer grouting material based on orthogonal experiment

Using the orthogonal experimental design method involving three factors and three levels, the flexural strength and the compressive strength of copolymer grouting material were studied with different compositions of water-cement ratio （mass fraction of water to cement）, epoxy resin content, and waterborne epoxy curing agent content. By orthogonal range and variance analysis, the orders of three factors to influence the strength, the significance levels of different factors, and the optimized compound ratio scheme of copolymer grouting material mixture at different curing ages were determined. An empirical relationship among the strength of copolymer grouting material, the water-cement ratio, the epoxy resin content, and the waterborne epoxy curing agent content was established by multivariate regression analysis. The results indicate that water-cement ratio is the most principal and significant influencing factor on the strength. Epoxy resin content and waterbome epoxy curing agent content also have a significant influence on the strength. But epoxy resin content has a greater influence on the 7-day and 28-day flexural strength, and waterborne epoxy curing agent content has a greater influence on the 3-day flexural strength and the compressive strength. The copolymer grouting material with water-cement ratio of 0.4, epoxy resin content of 8% （mass fraction） and waterbome epoxy curing agent content of 2% （mass fraction） is the best one for repairing of cement concrete pavement. The flexural strength and the compressive strength have good correlation, and the ratio of compressive strength to flexural strength is between 1.0 and 3.3.

Gel time of calcium acrylate grouting material

Calcium acrylate is a polymerized grout, and can polymerize in an aqueous solution. The polymerization reaction utilizes ammonium persulfate as a catalyst and sodium thiosulfate as the activator. Based on the theory of reaction kinetics, this study on the relation between gel time and concentration of activator and catalyst showed that gel time of calcium acrylate is inversely proportional to activator and catalyst concentration. A formula of gel time is proposed, and an example is provided to verify the proposed formula.

Property changes of anchor grout calcined ginger nuts admixed with fly ash and quartz sand after accelerated ageing tests

Calcined ginger nuts admixed by fly ash and quartz sand (CGN-(F+S)) has been validated to be basically compatible to earthen sites as an anchor grout. Accelerated ageing tests including water stability test, temperature and humidity cycling test, soundness test and alkali resistance test are conducted with the objective to further research the property changes of CGN-(F+S) grout. Density, surface hardness, water penetration capacity, water permeability capacity, soluble salt, scanning electron microscopy (SEM) images and energy dispersive spectrometry (EDS) spectrum of these samples have been tested after accelerated ageing tests. The results show that densities of samples decrease, surface hardness, water penetration capacity and water permeability capacity of samples increase generally. Besides, soluble salt analysis, SEM and EDS results well corroborate the changes. Based on the results it can be concluded that property changes are most serious after temperature and humidity cycling test, followed by water stability, soundness and alkali resistance test in sequence. But in general, CGN-(F+S) still has good durability.

考虑化学反应的高聚物压密劈裂注浆仿真研究

考虑浆液化学反应原理,综合运用扩展有限元理论、修正剑桥模型和高聚物浆液膨胀力计算模型,建立了模拟高聚物在土体中压密劈裂注浆动态过程的二维仿真分析方法。通过模型试验验证了所提出方法的适用性,进而分析了浆液膨胀力、浆脉形态、土体孔隙比随时间变化规律及注浆孔埋深、土体断裂韧度对浆脉扩展过程的影响。结果表明:受高聚物化学反应进程驱动,在浆液与土体耦合作用下,浆液膨胀力初期随时间近似呈线性增长,达到峰值后快速下降并趋于稳定;浆脉长度和宽度发展速度不同步,裂缝启裂至二次扩展阶段,浆脉长度基本保持不变,宽度线性增大,裂缝二次扩展后,浆脉长度近似线性增大,而宽度增长速率趋缓;受浆液挤密作用影响,裂缝两侧一定范围内土体孔隙比显著降低,沿垂直于裂缝面方向,距注浆孔中心越近,孔隙比越小;孔隙比随时间整体呈下降趋势,随着裂缝的扩展和后期膨胀压力的下降,紧邻裂缝面两侧土体孔隙比有一定恢复,随后趋于稳定;随着注浆孔埋深和土体断裂韧度的增加,浆脉长度逐渐减小,宽度不断增大,两者变化速率基本保持不变;浆脉扩展稳定时间随埋深的增大而提前,随断裂韧度的增大而延后。

冰碛土体化学浆液注浆扩散模式与距离影响机制研究

采用注浆法对土体进行固化的工程中,浆液在土体中的扩散距离是评估注浆效果的重要指标。为了探究化学浆液在冰碛土体中的扩散情况及其影响因素,通过自研的室内注浆实验装置,改变注浆压力,记录注浆时间、注浆量、浆液扩散距离等参数的变化,探究化学浆液在冰碛土体中的扩散距离影响机制。研究结果表明:①浆液的最大扩散距离主要取决于劈裂缝隙的扩散状况,最小扩散距离则与出浆口附近浆液的渗透距离有相关;②实验中注浆压力对浆液实际注入量的影响很小,不同注浆压力下的浆液注入量最大差异只有0.15 kg左右,且无明显规律;③浆液扩散模式以劈裂扩散为主,其次是渗透扩散,随着注浆压力的增大,渗透扩散的占比逐渐增大;④浆液的扩散距离主要受到注浆压力的影响,随着注浆压力增大而增大,注浆压力大于1.2 MPa时,扩散距离增幅有所提升。上述研究结论可以为冰碛土体的化学浆液注浆施工提供一定的理论依据。

地基处理技术及其工程应用研究

“一带一路”新时代背景下,我国基础设施和城市现代化建设日新月异,地基处理技术得到快速发展和应用。排水固结技术对于处治含水率高、孔隙比大,压缩性和灵敏性显著的软黏土地基,具有优异的效果,真空预压-堆载预压-电渗法联合加固则有利于全面提升软基加固质量;复合地基可有效发挥桩与桩间土的协同作用,有效控制沉降,结合工程应用分析了PCC桩、X型桩和挤扩支盘桩(DX桩)的截面特征与承载机理;阐释了渗透、压密及劈裂注浆的基本理论,并从复合水泥与超细水泥、地聚物、微生物菌液及高聚物材料方面梳理了注浆材料的工程应用进展。地基处理技术的发展进步,必将全面提升工程项目建设的精细化水平和质量。

锦屏二级水电站地下厂房母线洞及电缆交通道混凝土渗水裂缝化学灌浆施工技术

锦屏二级水电站地下厂房采用化学灌浆技术修补混凝土渗水裂缝,通过清理缝面、钻灌浆孔、洗孔、埋设灌浆嘴、封缝、灌浆、闭浆、缝面涂层保护等措施,裂缝处理完毕后表面无渗水。钻孔压水试验结果表明,该项目采用化学灌浆施工解决了裂缝渗水问题,达到了预期混凝土修补的效果。

地质构造带大巷顶板淋水注浆封堵技术

以中六运输大巷断层影响范围内顶板淋水防治为工程背景,提出采用RSS化学浆液对顶板淋水区进行快速封堵,同时采用U型钢架棚+聚氨酯浆液强化围岩支护强度,避免围岩变形产生新的导水裂隙。结合现场条件,对具体采用的顶板淋水注浆封堵技术方案进行设计,并进行工程应用。现场应用后,中六运输大巷顶板淋水问题得到较好解决,巷道围岩变形控制在安全范围内,采用的技术方案可满足中六运输大巷后续安全使用需要。

富水白云岩斜井注浆堵水技术应用研究

针对昆阳磷矿二矿胶带斜井开拓过程中遇到的水害问题,运用地质雷达和探水孔对巷道围岩的富水情况进行超前探测,查明了巷道围岩的破碎程度和富水特征,根据富水性探测结果,针对性地制订注浆堵水方案,由于巷道围岩属于节理裂隙发育的硬质岩,弱富水破碎带设计采用水泥注浆,强富水破碎带设计采用马丽散E化学注浆。在现场开展注浆试验,通过对比注浆前后的单孔涌水量和区段涌水量来评估注浆堵水效果,试验结果表明:化学浆液渗透性好,凝固时间短,平均堵水效率为76.6%,水泥-水玻璃浆液则为70.5%;通过对工作面分区段预注浆,能有效封堵涌水通道,改善工作环境和围岩条件,优化支护设计,每米支护成本降低了20%。研究成果可为类似地质条件下的巷道水害治理提供参考。

新型背水面防水防潮技术在水电站修缮工程中的应用

水电站墙面渗漏与结露危害是水利工程面临的一个关键问题,在分析其发生机理的基础上,引入了新型注浆技术及隔热保温技术以解决水电站渗漏、结露难题,弥补了前期单一防水抗渗措施的缺陷。通过安徽滁州琅琊山水电站地下厂房的工程实例,采用新工艺新材料的化学灌浆方法,达到了很好的防水防潮防结露的效果,并详细介绍了运用新技术进行渗漏修缮时每一道施工工序及对应的施工工艺流程。该方法对类似工程具有很好的指导价值和参考意义,同时对已经出现渗漏的水电站地下厂房提供一些治理经验。

考虑黏度时空变化特性速凝化学浆液渗透注浆机制

速凝双液化学浆液需采用静态混合方式施工,这使得浆液黏度随时间和空间变化而变化。以聚氨酯-水玻璃为典型速凝化学浆液,研究考虑黏度时空变化特性的渗透注浆机制,开展速凝化学浆液黏度时变试验,推导了一维渗透注浆的黏度时空分布方程、渗透运动方程和注浆压力时空演化方程,进一步推导了三维球形和柱形渗透注浆的黏度时空分布方程、渗透运动方程和注浆压力时空演化方程,建立了考虑黏度时空变化特性的球形和柱形渗透注浆理论;将已有的渗透注浆室内试验成果,以及开展的数值模拟研究,与推导的理论公式进行对比分析。根据结果可知,速凝化学浆液黏度随时间呈指数增长,与传统的Karol渗透注浆理论相比,考虑黏度时空变化特性的速凝化学浆液渗透注浆理论所预测的渗透半径更接近试验结果,所描述的渗透注浆现象与数值模拟结果吻合良好,验证了理论的准确性。

景洪水电站大坝结构横缝渗漏水下处理技术

针对景洪水电站12#—13#坝段结构横缝渗漏水问题,通过前期水下ROV检查及相关监测数据分析,项目设计采用结构横缝水下化学灌浆结合上游面水下设置表面接缝止水的方案,具体做法为采用LW/HW环保型水溶性聚氨酯灌浆材料封堵渗漏通道,并采用SR防渗体系封闭表面接缝。该做法消除了横缝渗漏,防渗效果显著。

水电站出线竖井渗漏治理

某水电站大型出线竖井井圈混凝土渗水,导致GIL接地铜排锈蚀。通过对出线竖井渗水规律的分析,在不影响出线竖井设备正常运行的前提下,采取系统布设排水管、定点钻孔引排、裂缝和施工缝化学灌浆补强处理等措施,实现了施工干扰小、出线竖井新增渗水点大为减少的效果。

尾矿资源化利用制备水泥注浆料的无侧限抗压强度预测

尾矿资源化利用制备水泥注浆料可实现尾矿的可持续性。为准确预测尾矿资源化利用制备水泥注浆料的无侧限抗压强度,基于K近邻回归、支持向量回归、随机森林、Gradient Boosting(GB)和Light Gradient Boosting Machine(LightGBM)算法,建立了无侧限抗压强度的预测模型。首先,收集了738组尾矿资源化利用制备水泥注浆料的无侧限抗压强度的试验数据,建立了无侧限抗压强度数据库,试验参数包括尾矿化学性质、水泥强度、水泥尾矿质量比、质量浓度、养护时间和无侧限抗压强度。随后基于该数据库,建立了K近邻回归、支持向量回归、随机森林、GB和LightGBM模型,选取了3个统计指标评估模型性能,并对比模型的精度和误差。结果表明:水泥与尾矿的质量之比与无侧限抗压强度的相关性最大,而在尾矿的化学性质中,二氧化硅含量对无侧限抗压强度的影响最大。在训练集和测试集上,支持向量回归模型的预测性能最好(决定系数R^(2)分别为0.99和0.98),且约99%数据的误差在1 MPa范围之内;GB模型的R^(2)分别为0.98和0.96,而K近邻回归模型的R^(2)分别为0.98和0.83。总体而言,支持向量模型的预测性能要优于GB模型、随机森林模型、LightGBM模型和K近邻回归模型,表明支持向量回归模型可准确地预测以及评估尾矿资源化利用制备水泥注浆料的抗压强度。本研究为尾矿在混凝土以及水泥等领域的资源化利用提供了基础。

环氧灌浆材料研究进展

随着高速公路交通流量和汽车荷重的增大以及使用年限的增加,路面病害日益显现,研发高性能化学灌浆材料已经成为当下迫切的需求。环氧树脂灌浆材料因其高强度、良好的力学性能和附着力、低收缩率和热稳定性等特点,成为一种极具发展潜力的灌浆材料。为了满足环氧灌浆材料在多方面的应用需求,已经有多种改性方法用于提高环氧灌浆材料的力学性能,如在分子链段中引入有机硅、醚基团等柔性基团,通过与聚氨酯共混形成互穿聚合物网络结构,以及添加纤维、纳米粒子等增强填料或其它方法获得高机械性能等。从结构改性、共混改性、掺杂改性以及其他方法几个方面综述了环氧灌浆材料的改性方法,并对环氧灌浆材料领域进行了展望。

混凝土浅层裂缝化学灌浆施工造价分析

在水电工程中,对混凝土浅层裂缝化学灌浆无类似定额子目可供参考组价,水电建筑工程预算中现有化学灌浆定额子目仅适用于廊道内、混凝土底板等大体积型混凝土裂缝处理,其与混凝土浅层裂缝处理施工工艺存在较大差异,无法通过替换人材机参照使用,因此,本文结合混凝土浅层裂缝具体的化学灌浆方案,通过对现场资源投入量的统计与分析和参考相关行业类似的定额子目,采用施工成本法和预算定额法对混凝土浅层裂缝化学灌浆施工造价进行分析与计算,得出灌浆材料和计量单位是影响施工造价的核心要素,旨在为类似项目的费用估算提供参考借鉴。