陈村大坝丙凝化灌帷幕

一、前言本文通过陈村水电站帷幕工程实例,分析了工程地质和水文地质条件对水泥帷幕灌浆和大坝基础防渗处理的影响。介绍丙凝化灌帷幕的实效,论证丙凝化灌解决了水泥灌浆不能解决的防渗问题,工程效果较为显著。指出在一定工程条件下,丙凝化灌作为一种防渗止漏的有效手段,只要设计和施工中正确分析、合理运用,就可以优质快速地筑成较为理想的、永久性的防渗帷幕,这将有助于更快地发挥水电建设的效益。     

套管水泥环组合抗挤强度模型及其弹性分析

建立了套管水泥环组合抗挤强度模型，导出了管外水泥环对套管屈服抗挤强度的影响系数，提出了套管水泥环组合抗挤强度弹性概念；计算分析了管外水泥环的存在对套管屈服抗挤强度的影响程度，并对套管水泥环组合抗挤强度对套管水泥环参数变化的敏感性，即套管水泥环组合抗挤强度弹性进行了计算分析。     

第三次化学灌浆学术交流会简况

第三次水利水电化学灌浆学术交流会于1980年5月14日至20日在长沙召开,有95个单位、145名代表参加,会议共收到论文65篇。会议总结交流了1975年第二次化灌会议以来在化灌方面的科研成果和技术经验。五年来在水利水电化灌技术上取得了可喜的进展,这些进展主要表现在:1.化灌技术在水利水电工程中得到了较为广泛的应用。例如应用丙凝、木质素和聚氨酯在砂基和岩基内建造防渗惟幕和处理断层软弱夹层,用甲凝和环氧树酯在坝体混凝土裂缝中进行补强,用聚氨酯进行裂缝动水堵漏,用水泥水玻璃进行围堰基础和隧洞工程的防渗加固处理等。化学灌浆已经解决了水泥灌浆     

MMA混凝土修补材料二次灌浆研究

采用甲凝（MMA）灌浆时会因其收缩较大而影响粘结效果,文中从施工工艺的角度进行理论分析和实验验证,证明二次灌浆能有效减弱MMA收缩引起的不良影响,提高粘结体的抗折粘结强度,并确定了最优补灌时间和选择补灌浆液时的最优初始粘度、胶凝时间、可灌性、抗折粘结强度、断裂伸长率、相对收缩率等,可供参考。     

灌芯混凝土砌体抗剪强度的理论分析和试验研究

对灌芯混凝土砌体抗剪强度进行了试验研究 ,应用刚塑性极限分析理论进行了灌芯混凝土砌体抗剪强度的理论分析 ,提出了灌芯混凝土砌体抗剪强度的理论计算式 ,根据试验研究得出了它的实用计算式     

三元胶凝体系复合墙板材料抗折试验研究

以工业固废矿渣微粉、粉煤灰、脱硫石膏构成三元胶凝混合料替代50％水泥,开展复合墙板材料7 d、28 d抗折强度试验,研究并讨论三元胶凝混合料胶凝比在替代水泥率为50％时对其的影响.结果表明:矿渣微粉-粉煤灰-脱硫石膏三元胶凝混合料拌制比例对7 d和28 d的抗折强度影响趋势基本一致;无论是7、28 d抗折强度,当矿渣微...     

充灌袋挤淤筑路方法研究

根据大型充灌袋在天津滨海新区修建围埝和道路的工程实践,提出了采用大型充灌袋在吹填土上直接筑路的理论和方法。该法采用大型充灌袋作为路堤,首先利用充灌袋的挤淤作用使其底部落位在承载力较高的土层,然后通过打设排水板,对袋底以下土层进行进一步加固。充灌袋的充填材料为粉土,解决了天津砂源少的难题。总结了充灌袋挤淤筑路的结构形式和施工工艺．提出了充灌袋挤淤沉降的机理与计算方法,计算了充灌袋的挤淤深度。根据巴隆固结理论对充灌袋底部土体的固结度进行了计算,得出了道路建成后一定时间内的固结沉降,根据固结沉降量的大小可确定是否继续吹填充灌袋,以达到路面设计标高。以上计算结果与实际工程的检测结果较吻合,为完善大型充灌袋筑路法的设计提供了理论依据。     

浸水对黄土中静压桩挤土效应影响因素的分析

通过分析浸水过程中挤土应力、体应变的变化规律得出:浸水造成挤土应力进一步衰减,但浸水造成的应力衰减幅值不大;在应力-应变塑性区的压缩体应变大于弹性区的体应变值,且浅部塑性区土体有湿陷的可能。对浸水前、后黄土力学参数的对比表明:经过沉桩后,挤土和浸水作用,使黄土的弹性模量增大,极限强度降低,而抗剪强度参数与受到的挤土应力水平相关。基于考虑浸水软化的屈服面概念,说明在应变保持和浸水阶段塑性区土体处于剪切蠕变状态,即处于从天然状态的屈服面过渡到饱和状态的屈服面的过程。     

挤液法油管防凝工艺技术分析及替代方案

海上油田使用离心式潜油电泵进行高凝固点油藏开发时,为防止油井长期关井状态下原油在油管内凝结,发生油管凝管堵塞问题而影响潜油电泵的再启动,油井停井后,常采用向油管内挤柴油或海水的方法置换油管易凝管段原油。根据对挤液法防凝工艺技术的分析及油田应用实践,指出了设计挤液法工艺时应考虑的因素及应用该方法过程中存在的问题,讨论了各种井况下的可行性替代方案,对指导海上油田油井长期关井期间油管防凝方案设计及油田现场对高凝固点油井防凝管理具有重要的现实意义。     

螺旋锥体挤土压灌桩施工工艺与质量控制研究

根据螺旋锥体挤土桩的施工方法以及钻头专利,结合该工法施工的多项工程案例,给出了螺旋锥体挤土压灌桩施工的条件,并分析了该施工工法的优势与特点;设计了螺旋锥体挤土压灌桩施工工艺流程图,并针对施工中出现的质量通病,提出了7项施工质量控制关键点,同时结合工程检测,提出了螺旋锥体挤土压灌桩的加强质量技术措施。经施工验证,各项工程均满足标准要求,为类似工程施工提供借鉴。     

Study of a new cheap grouting material: clay-hardening grout

The paper discusses factors that affect gel time and strength of anew, cheap grouting material: clay-hardening grouts (CHG). A special quality of these grouts is that they may be grouted repeatedly. The concept of a “groutable period” (GP) is introduced in connection with this quality. Results of a comparison of a CHG with an ordinary cement grout are presented, and an example of a practical engineering application of a CHG is discussed.     

Laboratory pull-out tests on fully grouted rock bolts and cable bolts:Results and lessons learned

Laboratory pull-out tests were conducted on the following rock bolts and cable bolts:steel rebars,smooth steel bars,fiberglass reinforced polymer threaded bolts,flexible cable bolts,IR5/IN special cable bolts and Mini-cage cable bolts.The diameter of the tested bolts was between 16 mm and 26 mm.The bolts were grouted in a sandstone sample using resin or cement grouts.The tests were conducted under either constant radial stiffness or constant confining pressure boundary conditions applied on the outer surface of the rock sample.In most tests,the rate of displacement was about 0.02 mm/s.The tests were performed using a pull-out bench that allows testing a wide range of parameters.This paper provides an extensive database of laboratory pull-out test results and confirms the influence of the confining pressure and the embedment length on the pull-out response(rock bolts and cable bolts).It also highlights the sensitivity of the results to the operating conditions and to the behavior of the sample as a whole,which cannot be neglected when the test results are used to assess the bolt-grout or the grouterock interface.     

富水破碎岩体注浆加固实验与机制研究

 采用模拟富水破碎岩体注浆的方法,开展普通硅酸水泥42.5#(PO.42.5)、硫铝酸盐水泥42.5#(SAC.42.5)和自主研发水泥基复合注浆材料(CGM)的注浆加固效果实验。通过对比破碎灰岩和破碎砂岩试样注浆后结石体的单轴压缩实验结果发现,岩体破碎程度越高,注浆后强度改善效果越明显,岩石孔隙率越大,注浆后韧性增强显著。CGM材料对应注浆加固结石体强度显著高于PO和SAC材料,对多孔隙砂岩的刚性改善效果最优,且结石体沿岩–浆界面产生滑移破坏的概率最小,SAC材料次之,PO材料最差。采用扫描电子显微镜测试手段,分析岩–浆界面过渡区域矿物种类及分布形态,揭示了不同水泥类材料注浆效果产生差异的原因,从微观角度确定了岩–浆界面的胶结类型主控因素为岩石的岩性,与水泥材料类型无关。对于致密度高的灰岩类岩石属于Ollivier-Grandet模型,对于多孔隙砂岩类岩石属于Zimbelinan模型。结合对岩–浆界面过渡区域X射线衍射分析和元素扫描分析结果,证明注浆不仅改善岩石的物理力学性能,还会引发岩石组分发生化学变化,在界面区域生成类岩石矿物,可提高岩–浆界面胶结强度。     

全长粘结型锚杆加固岩石边坡应力与变形特性数值分析

通过有限元数值模拟方法 ,对全长粘结型锚杆加固的均质岩石开挖边坡进行了数值计算 ,并分析研究了加锚边坡的应力与变形特性和全长粘结式锚杆轴力分布规律 ,提出了一种简单实用确定边坡可能滑动面的方法 ,并且指出了在边坡锚杆支护设计中应注意的一些问题。     

Cement–clay grouts modified with acrylic resin or methyl methacrylate ester: Physical and mechanical properties

Grouting is a common technical method with many applications, e.g. it is used for soil stabilization and strengthening, for reduction of water ingress to underground facilities or of the water loss through a dam foundation, etc. Grouts comprise several constituents, which are combined in many ways depending on the in situ conditions and the outcome desired. Superplasticizers, accelerators, antifreezers, air-entraining agents and many others are generally used to improve the quality of cement grouts and consequently, their effectiveness on strength (especially bond strength), durability, impermeability and resistance to chemical erosion of the grouted soil or rock mass. A comprehensive laboratory work was carried out in order to study the physical and mechanical properties of grouts prepared by using cement, clay, water in different percentages along with an amount of acrylic resin or methyl methacrylate co-polymer emulsion. Flowability, setting time, bleeding, compressive strength, elastic modulus, shear bond strength, resistance to wet–dry cycles and resistance to sulfate attack of the grouts were determined. The results of this study indicated that the addition of latexes improves significantly the compressive strength, shear bond strength, stability, resistance to wet–dry cycles and resistance to sulfate attack, especially for thick pure cement grouts. This improvement depends on the type of latex.     

Tensile properties and pullout behaviour of AFRP and CFRP rods for grouted anchor applications

Fiber-reinforced-plastic (FRP) rods have been introduced in the market for grouted ground anchors. The resistance to corrosion and chemical attack, high strength-to-weight ratio, and ease of handling of these rods make them a better alternative to steel tendons in some applications of ground anchors. However, to fully utilise FRP rods as tendons for cement grouted anchors, some aspects of their behaviour have to be determined, including tensile properties, tensile capacity, bond strength in cement grout, long-term strength and durability in alkaline environments. In this paper, the tensile characteristics, bond strength and pullout behaviour of AFRP and CFRP rods embedded in cement grout are discussed. The pullout test program involved four types of rods, four types of cement grouts and three types of anchorage tubes with three bonded lengths. The experimental results have shown that the tensile properties of the FRP rods are close to the manufacturers’ data. The surface geometry of FRP rods, the properties of the filling grout and the stiffness of the host medium (anchorage tube) influence the pullout behaviour, pullout capacity and maximum bond stress of cement grouted FRP anchors.     

Grouting field experiment at the Äspö Hard Rock Laboratory

This paper presents a field experiment in grouting a fracture at the Äspö Hard Rock Laboratory in Sweden. The fracture was investigated and described in terms of transmissivity, from which a prediction of grout spread was made, based on calculations that included a model for the penetrability of cement-based grouts. In the practical part of the experiment, the fracture was grouted and separated from the rock so that visual and chemical investigations could be performed. The grout spread evaluated from the separated fracture was found to agree with the prediction. It was verified that the grout spread was halted by the limited penetrability of the grout, which was in accordance with the prediction.     

软土中注浆与未注浆抗拔桩受力性状对比试验研究

在杭州萧山一工地未注浆与注浆试桩抗拔静载试验的基础上,发现抗拔桩经过桩端后注浆可显著减少桩端位移,极限抗拔力至少提高25%,最大桩身拉伸量占桩顶上拔量的91.5%。注浆与未注浆桩的桩身轴力都随深度逐渐减少,桩端轴力始终为0;浆液上返高度16.9m范围内注浆桩侧摩阻力有较大幅度的提高,最大提高幅度为83.3%;在利用浆液上返高度公式计算注浆抗拔桩竖向增强体高度和考虑桩身自重的基础上,提出桩端后注浆抗拔桩承载力的估算公式。通过反分析计算,未注浆桩抗拔折减系数的取值范围为0.65～0.80,注浆桩侧阻力增强系数的取值范围为1.33～1.83,计算方法与结果可供初步设计与实际工程使用。     

点滴化学注浆技术加固土遗址工程实例

 表面防风化问题一直是土遗址保护研究的重点和难点。将开发研制的点滴化学注浆装置应用于工程实际,对堂加2 #土遗址表层进行化学加固,内容包括：室内模拟场地点滴注浆试验、浆液固化体三轴试验、微观结构扫描电镜(SEM)观察、现场模拟土遗址的点滴注浆试验、点滴化学注浆技术加固堂加2#土质古窑。试验结果表明：(1) 点滴化学注浆装置采用的气球密封注入前端构造,可有效解决注入过程中浆液外溢问题,并可在地下遗址顶部及其附近实现由下而上的化学注浆加固;(2) 化学加固剂(硅酸乙酯)通过改善土粒团块之间的胶结状态,可有效提高遗址土的黏聚力,对内摩擦角的影响不甚明显;(3) 点滴化学注浆技术可对预定厚度的遗址土进行有效加固,克服了喷涂工艺加固深度浅且易出现两张皮的现象;(4) 点滴化学注浆技术对堂加2#土质古窑的成功加固,验证了该技术的现场适宜性和可行性,对类似的土遗址固化处理具有借鉴和参考意义。     

Sealing narrow fractures with a Newtonian fluid: Model prediction for grouting verified by field study

The increased demand for efficiency when sealing tunnels by grouting has led to a need to seal narrow fractures. The more conductive fractures are sealed by cement-based grouts, however, the limitations in penetrability make these grouts less useful for low permeable rock. Silica sol is an inorganic grouting material with high potential to penetrate narrow fractures. Its two components, silica sol and a salt solution, are both considered harmless. The salt solution (CaCl₂) is the accelerator. The field study investigates whether the penetration of a Newtonian fluid (silica sol) can be predicted and verified using numerical models, based on grout properties and hydraulic tests. The field study was conducted, in 2004, on a pillar located at 0/670 m at Äspö Hard Rock Laboratory (Äspö HRL).One, well characterised and grouted fracture was selected to be grouted with silica sol and analysed. To check the conditions of the fracture hydraulic tests were used, namely, constant head tests with single packer and they were directly followed by pressure logging in the recovery phase. The transmissivity, T, was estimated from the recovery phase of single-hole injection tests using Jacob’s method. Further, the hydraulic aperture was estimated using the well-known cubic law. For the design of the grouting parameters, gel time, injection pressure, and injection time were determined from a one-dimensional model with the penetration length set to 2.2 m. The grout was mixed with optical brightener to make the grout easier to see in the six cores drilled. The grouted borehole was over-cored, and specimens from the grouted fracture were analysed by microscope. Hydraulic tests were made after grouting to estimate the sealing efficiency of the rock mass. The penetration was also estimated in a two-dimensional model to verify length for selected grouting times.Visual observation and the hydraulic properties of two boreholes show that the penetration length is at least 1.0 m. For the numerical model in 2D, a good agreement is found. The final penetration is underestimated by the model underestimates. The hydraulic tests show that at least two boreholes were sealed with silica sol within the predicted penetration radius. The sealing efficiency was approximately 70%.