Control of rock jacking considering spread of grout and grouting pressure

This paper describes a theoretical approach for monitoring fracture dilatancy (or “jacking”) during grouting. From this, a methodology to optimize the grout pumping pressure has been developed, based on the required penetration length (i.e. the distance that the grout spreads from the grout hole into the network of fractures within the rock mass). Empirical rules are put forward to prevent the damage that may result from uncontrolled deformation (Jacking) of the fractures, by limiting either pumping pressure or the injected grout volume, or by a combination of both. The state of the fractures and the spread of the grout when these limits are reached are discussed. The theoretical approach, which is referred to here as the Real Time Grouting Control Method, enables the estimation of grout penetration length or “spread” in real time. This gives an opportunity to monitor fracture dilation as it happens and, for the purpose of this paper, the allowable limits of elastic deformation and jacking have been estimated based on the grout spread. Two case histories are analyzed, for which the physical reaction of the fracture deformation with time and grout spread are determined from the recorded pressure and flow. By comparing the observed physical reaction with the theories for jacking presented here, the Real Time Grouting Control Method has been validated, and it is shown that this theoretical approach is superior to commonly used empirical methods, in that it allows the optimization of the pumping pressure to achieve a given penetration length in the shortest time and with an acceptable fracture dilatancy. This approach is a major step forward in customizing grouting works.     

桩端压力注浆在人工挖孔灌注桩中的应用

论述了桩端压力注浆的作用机理，结合某建筑物场地的工程概况，经分析确定了人工挖孔桩的施工方案，介绍了桩端压力注浆在人工挖孔灌注桩中的应用，取得了良好的施工效果。     

压密注浆技术在地基加固中的应用

结合福建某厂房的工程实例,介绍了压密注浆在地基加固中的应用,阐述了压密注浆加固机理、设计方案、施工工艺以及施工中应注意的问题。     

深部隧洞裂隙围岩渗透特性及衬砌外水压力变化规律

高外水压岩是影响隧道开挖过岩围岩稳定及衬砌结构安全的关键因素之一,基于裂隙介质渗流经典理论,给出围岩、衬砌不同渗透系数下的外水压岩解析解,采用数值方法对隧洞二次衬砌后的外水压岩作用特性进行仿真模拟,探讨裂隙围岩岩衬砌渗透系数对渗流场的影响,围岩、衬砌渗透和排水措施岩外水压岩的相关性。研究表明岩体和衬砌渗透系数之比是影响衬砌外水压岩的关键,正确的灌浆、排水设计对外水压岩折减系数影响较大,是减小衬砌外水压岩的有效措施。结论对高压水作用下裂隙岩体渗流及衬砌外水压岩研究具有重要理论意义,对高水压下围岩注浆及衬砌结构材料选型、参数选择等具有重要岩岩实用价值。     

压力注浆法补强地基在施工中的应用

结合工程简介及地基状况,对不均匀沉降进行了原因分析,制定了压力注浆法补强地基方案,阐述了压力注浆加固步骤和施工控制,并对压力补强效果进行了有效验证,从而为压力注浆法补强地基在施工中的应用积累经验。     

低压注浆与旋喷桩技术在岩溶塌陷治理中的应用

龙厦铁路象山隧道岩溶突水,导致某水泥厂大面积地面塌陷,厂区建(构)筑物发生开裂和不均匀沉降,其中一期、二期烧成窑头墙体及地面出现起拱及裂缝。经研究决定采用高压旋喷桩结合低压注浆方案进行加固。即采用高压旋喷桩对窑头篦冷机基础进行加固处理,加固区域地基土则采用低压注浆进行加固,取得了较好的加固效果。     

采用压力灌浆处理砖砌体裂缝

介绍了压力灌浆处理砖砌体裂缝的适用范围，结合该技术特点，详细阐述了其施工工艺措施，提出了施工中的注意事项，并例举了两个成功应用的工程实例。     

注浆加固技术在软弱地基处理中的应用

结合具体工程实例，探讨了压力注浆加固软弱地基的作用机理，对施工过程及其控制作了阐述，并对加固效果进行了检测及结果分析，可供类似地基处理工程施工参考。     

高喷灌浆技术在工程中的应用

就高喷灌浆技术在河道治理中用于地下垂直防渗的施工进行了简要介绍。     

论超长大体积混凝土无缝施工技术

通过分析大体积混凝土温度变化机理,对大体积混凝土的结构计算温差及温度应力计算给出了较简便的方法;并对温度监测、施工措施等方面进行了探讨。结合工程实例,介绍了某大体积混凝土工程的裂缝控制方法。     

高压旋喷注浆在桩基加固中的应用

在桩基加固工程中采用高压旋喷注浆法,结合厦门某办公楼静压预应力管桩加固的工程实例,为类似工程提供了很好的借鉴。     

高压旋喷桩复合地基在岩溶地区中的应用

通过工程实例,阐述了高压旋喷桩复合地基在岩溶地区中的应用,验证了该施工方案的可行性,指出旋喷桩具有经济、环保、施工方便等优点,具有良好的经济效益和社会效益,以推广旋喷桩在地基处理中的应用.     

圆形压力隧洞限裂配筋设计方法研究

为研究圆形压力隧洞衬砌合理的限裂设计方法,采用钢筋混凝土有限单元法对隧洞衬砌的受力特性进行分析,指出隧洞衬砌具有内力值随衬砌开裂区域增加而减小、配筋取决于裂缝宽度的限制要求而非承载力、规范中的裂缝宽度计算公式不适用等特性。通过对厚壁圆筒承载力计算公式的重新推导,指出该方法没有引入裂缝处环向钢筋应变最大值与环向钢筋在整个圆周内平均应变的比值ψ’,使得钢筋面积计算值过小。鉴于隧洞衬砌的受力特性及没有合适的ψ’计算方法,建议取消厚壁圆筒公式,而采用钢筋混凝土有限单元法进行隧洞衬砌的配筋计算。对能由有限元计算直接求得裂缝宽度的衬砌,以裂缝宽度限值要求确定钢筋用量与布置;对不能由有限元计算直接求得裂缝宽度的衬砌,以限制钢筋应力来控制裂缝宽度,即以钢筋应力限值要求确定钢筋用量与布置。最后,通过较多的算例给出隧洞衬砌的钢筋应力限值,当保护层厚度为50mm时钢筋应力限值可取120MPa,当保护层厚度为100mm时钢筋应力限值可取100MPa。     

循环经济模式下钢渣用于透水透气型混凝土开发

本文以钢铁企业生产过程中产生的钢渣为研究对象,应用工业工程的基本原理对钢渣的透水性、稳定性进行综合研究试验分析,将其钢渣制成透水透气环保型混凝土,除普通钢渣的二次污染问题,实现循环经济,社会价值巨大。     

高压喷射注浆技术在深基坑工程中的应用

结合工程实例 ,简述高压喷射注浆技术在深基坑围护工程中的应用过程和控制要点     

Analysis of unlined pressure shafts and tunnels of selected Norwegian hydropower projects

Norwegian hydropower industry has more than 100 years of experiences in constructing more than 4000 km-long unlined pressure shafts and tunnels with maximum static head of 1047 m (equivalent to almost 10.5 MPa) reached at unlined pressure tunnel of Nye Tyin project. Experiences gained from construction and operation of these unlined pressure shafts and tunnels were the foundation to develop design criteria and principles applied in Norway and some other countries. In addition to the confinement criteria, Norwegian state-of-the-art design principle for unlined pressure shaft and tunnel is that the minor principal stress at the location of unlined pressure shaft or tunnel should be more than the water pressure in the shaft or tunnel. This condition of the minor principal stress is prerequisite for the hydraulic jacking/splitting not to occur through joints and fractures in rock mass. Another common problem in unlined pressure shafts and tunnels is water leakage through hydraulically splitted joints or pre-existing open joints. This article reviews some of the first attempts of the use of unlined pressure shaft and tunnel concepts in Norway, highlights major failure cases and two successful cases of significance, applies Norwegian criteria to the cases and reviews and evaluates triggering factors for failure. This article further evaluates detailed engineering geology of failure cases and also assesses common geological features that could have aggravated the failure. The minor principal stress is investigated and quantified along unlined shaft and tunnel alignment of six selected project cases by using three-dimensional numerical model. Furthermore, conditions of failure through pre-existing open joints by hydraulic jacking and leakage are assessed by using two-dimensional fluid flow analysis. Finally, both favorable and unfavorable ground conditions required for the applicability of Norwegian confinement criteria in locating the unlined pressure shafts and tunnels for geotectonic environment different from that of Norway are highlighted.     

高压旋喷桩复合地基在回填区的应用

提出了在多障碍物回填区采用高压旋喷桩代替CFG桩或与CFG桩协同作用的地基处理方法,并介绍了此方案的施工参数和控制要点,从而达到指导同类工程的目的。     

有限元预测温度场技术在博兴交通家园住宅工程的应用

本文采用混凝土半绝热温升试验与有限元计算方法,预测了博兴交通家园住宅工程施工期混凝土的温度场变化情况,用以指导工程施工。在施工过程中,对工程计算部位混凝土的温度变化进行了适时监控。工程实践表明,预测计算结果与实测基本吻合,对施工中的温度控制具有比较好的指导作用。     

压浆技术在冲(钻)孔灌注桩中的应用

压浆技术指在冲(钻)孔灌注桩成桩后,通过预埋在桩身的注浆管,利用压力作用,将能固化的浆液经预留注浆装置注入桩端地层,提高桩的承载力,减少桩基沉降量。     

压力灌浆在地基处理中的应用

介绍了介休维群集团公司甘油项目发酵车间生产楼运用压力灌浆法对地基土的加固处理工程，分析了压力灌浆的工作原理，探讨了其在地基处理工程中的效果和制约因素，对同类工程有一定的参考意义。