考虑注浆压力的顶管施工引起土体变形计算方法

顶管施工引起周围地层变形的计算预测是顶管施工中必须加以重视的问题。地层的沉降变形与顶管施工的几个环节有密切的联系,如：①顶管姿态与开挖面土压;②顶进与换管;③注浆过程等。理论分析应考虑这几个施工中的关键因素。针对上述施工影响因素,提出了考虑注浆压力的顶管施工的地层移动的计算方法。用Mindlin的位移解分析模拟开挖面土压、顶进与换管过程中的侧面摩擦力的变化引起的位移;以Sagaseta的土体损失引起的土体位移模式分析姿态控制、土体损失等引起的变形;将圆孔扩张的Verruijt解拓展到三维,用于计算注浆压力引起的位移与变形。结果表明,考虑注浆压力的变化,可以得到更为合理的预测结果。     

灌浆钻灌一体化工艺实践与探讨

历来灌浆是由两个不同的工序组合起来的,即成孔与灌浆,成孔由一套钻具完成,灌浆又是由另一套灌浆管系列完成,之间无相联关系。因此,在某些施工区域,可由钻机组与灌浆组分别完成。通过工艺改进后,可将成孔与灌浆改为一个工序,使灌浆质量与效率均能得到提高。介绍了钻灌一体化技术的原理、工艺流程及其工艺特点,并列举了工程实例。     

地铁隧道下穿小河和桥梁的施工方案研究

综合工程经验,对北京地铁5号线过河过桥隧道施工可能采用的4种超前支护方案即水平旋喷桩、全断面深孔注浆、长管棚、加密小导管注浆并辅以临时仰拱进行初步分析,认为加密小导管方案在施工造价、掘进速度和施工影响方面具有优势。采用三维数值模拟方法对长管棚方案和加密小导管方案进行进一步评价并择优。数值模拟结果显示,在不计管棚施工对地层提前扰动的情况下,长管棚方案与加密小导管方案对桥台、桥墩以及小月河河底的影响是相当的,可以认为,加密小导管方案将优于长管棚方案;长管棚、小导管和锁脚小导管承受弯矩较小,锁脚小导管以及隧道拱部的小导管承受轴压力,边墙的小导管既承受轴压力又承受轴拉力,长管棚主要承受轴拉力。     

钢管柱逆作法施工实践

钢管柱逆作法施工时,一方面其水平位移、垂直度等要求非常高,采用普通支撑立柱的施工方法很难达到设计要求;另一方面,在结构设计时,桩身砼与钢管内砼标号不一致,控制好高低标号砼的浇筑质量又是一大难题。通过武汉南国中心一期试桩工程实例,从钢管柱定位、垂直度控制和高低标号砼的浇筑3个方面介绍了逆作法钢管柱施工方法。     

套管伸缩器及定位钢管桩在滨海浮船平台绳索取心钻进中的应用

随着探矿领域不断扩展,滨海探矿项目越来越多。在滨海水上钻探中,由于受海浪、涨落潮、暗流、大风等不稳定因素影响,存在钻具横向、竖向定位控制困难等问题。采用＂浮船＋钢管桩＋伸缩器套管＂工法能较好地解决这2个难题。结合工程实践,介绍了套管伸缩器及定位钢管桩在滨海绳索取心钻探中的组合应用。     

袖阀管注浆工艺在柔性接头地下连续墙施工中的应用

北京朝阳区一管廊地下连续墙施工项目,因场区内工程、水文地质条件和施工场地局限性等因素,为节约经济成本和减少地连墙接头处渗水对后续结构防水施工的影响,采用了袖阀管注浆的防渗处理措施。介绍了袖阀管注浆工艺的施工方法,验证了该工艺处理地连墙柔性接头的防渗措施完全可行。     

管幕冻结隧道“顶管?冻土”复合结构力学特性试验研究

拱北隧道暗挖段作为港珠澳大桥珠海连接线的重点工程,首次运用管幕冻结法进行施工。该法综合管幕法和人工地层冻结法的优势,可在隧道断面形成“顶管?冻土帷幕”复合支护体系,有效实现“承载”与“顶管间止水”的双重目标,确保隧道开挖时的稳定与安全。为获得“顶管?冻土”复合结构的温度、变形与力学特性,基于相似理论自主研发构建一套相似模型试验系统并开展试验研究,同时利用有限元软件COMSOL Multiphysics建立数值计算模型进行模拟验证。结果表明:复合结构的冻结温度场因空、实顶管及其内部冻结器的布置形式呈现不均匀分布特征,冻土形成速率在冻结后期明显变缓;土体竖向冻胀变形在60~160 min内急剧增大,且冻胀量随深度增加而增大,整体规律与温度场分布密切相关;土体冻结产生的冻胀力对顶管水平受力影响较大,空顶管相对刚度较小而产生较大水平变形;在加载阶段,顶管受力与变形均以竖向为主。因空、实顶管刚度差异和冻土厚度不均匀的共同影响,空顶管竖向变形包含了“弯曲”与“压扁”并具有非线性特征,其跨中截面底部竖向位移峰值约为实顶管的1.6倍;加载至0.28 MPa时,管间冻土首先发生破坏,进而导致顶管间封水功能失效,实际施工中应重点监测空顶管的变形规律、管间冻土帷幕的温度变化及其完整性。研究成果可为管幕冻结法的施工与监测提供参考,也可为热力耦合数值计算模型提供验证依据。      

The influence of the degree of saturation on compaction-grouted soil nails in sand

A series of large-scale model tests was conducted on compaction-grouted soil nails to study the influence of the degree of saturation on the soil response to compaction grouting and pull-out. The experimental results show that the initial degree of saturation of the soil strongly influences the grout injectability, thus the formed diameter of grout bulb. Subsequently, the diameter of the grout bulb alters the pull-out force, with larger grout bulbs generating higher pull-out forces and exhibiting greater hardening behaviour. Interestingly, the initial pull-out forces are the same for the same grouting pressure, regardless of the initial degree of saturation and the subsequently grout bulb. In addition, some of the main factors influencing the pressure grouting and pull-out of the soil nail, as the initial degree of saturation varies, are as follows. First, the variations in the soil pressure and density with the initial degree of saturation are similar to that of the volume of grout injected, and the compression of the soil induced by pressure grouting exhibits a similar evolution with the initial degree of saturation at different locations. Second, the initial degree of saturation of the soil sample plays a dominant role in the change in suction during pressure grouting and pull-out of soil nail. Third, the horizontal soil pressure derived from the pull-out of soil nail propagates closely in the soil sample of lower initial degree of saturation. The vertical soil pressure induced by the vertical soil dilation and squeezing effect varies in accidence with the initial degree of saturation and the grout bulb.

     

The compaction effect on the performance of a compaction-grouted soil nail in sand

In this study, two series of physical modeling experiments, with and without a grouting process, were conducted under different grouting pressures to study the effect of compaction grouting on the performance of compaction-grouted soil nails. In addition, a hyperbola-based model was proposed to describe the variation of the pullout forces with and without grouting. Some of the main conclusions drawn are as follows. First, the compaction effect initially influences the mobilized pullout force, but not the final stage of pullout; the large difference between the two series of tests in regard to the pullout force at the initial stage led to the first part of this conclusion. However, the final pullout force results of the tests, both those with and those without grouting, were similar. Second, once the soil condition changes, the compaction effect on the performance of a soil nail depends on the grouting pressure rather than the diameter of the grout bulb. Third, the difference in the soil response (i.e., vertical dilatancy and the vertical and horizontal squeezing effects) derived from the compaction grouting effect will result in the initial difference in the increased rate of the pullout force between the tests with a grouting process and those without. Finally, a hyperbola-based model was proposed to describe the variation of the pullout force of the model tests with and without grouting, through which the pullout force is available of prediction for the given diameter of grout bulb and pullout displacement.

     

灌注桩套管高频振动贯入过程中挤土效应研究

随着全套管振动取土灌注桩施工工艺的发展,灌注桩在工程中的应用越来越广泛,但关于灌注桩套管高频振动贯入机制,特别是套管贯入引起的挤土效应研究还不全面。全面介绍了套管高频振动贯入全过程的有限元-无限元耦合模型的建立过程后,对地表隆起、土体侧移及超孔隙水压力等挤土效应的变化规律进行了详细研究。研究结果表明：水平向的挤土位移随套管贯入深度的增加而增大,竖向挤土位移随着套管贯入深度的增加,浅层土表现为隆起量增大,而深层土表现为下沉量增大;最大挤土位移与套管贯入深度存在滞后效应;浅层土体的隆起为水平向应力加载引起竖向应力增加所致,且隆起分界面深度随着动力荷载幅值增大而增大,随振动频率的增大而减小;超孔隙水压力随套管贯入深度增加而增大,随径向距离增大呈指数型衰减。     

钻孔救援连续缆管储放设备研制

双钻头仿生自平衡连续钻进技术具有无需钻机、钻进速度快和对井壁扰动小等优点,是构建矿山灾害保障救援通道的潜在关键技术之一。该技术中的连续缆管由于内置有电源、信号和排屑等通道,要求在储放过程中不能出现像现有滚筒式绞车储存连续管时存在的互咬、挤压和设置动静导电滑环等情况,故需研制与之匹配的专用连续缆管地面储放设备。依据双钻头自平衡钻进技术的需求和连续管滚筒式绞车储存技术存在的不足,提出了连续缆管套筒式储存和夹持式输送原理,构建了连续缆管套筒式储存和输送模型,并应用有限元分析软件对连续缆管的夹持输送过程进行模拟分析。依据双钻头仿生自平衡钻进系统对连续缆管的性能要求,确定了整机尺寸参数,并对整机的运行参数进行了计算,建立了适用于连续缆管外径为50.8 mm、井眼深度小于1 016.8 m、场地面积小于50 m2钻井工况的钻孔救援连续缆管储放设备三维模型。最后,研发了与本设备匹配的电控系统,并对加工组装好的整机进行了连续缆管夹持输送、储放设备运行、连续缆管储放等机电一体化联调与试验。结果表明：连续缆管储放设备运行平稳,在连续缆管存储和输送过程中,无互咬和锁死现象,没有动静导电滑环,能够满足双钻头仿...     

Formation of fluidization pipes during liquefaction: examples from the Uratanna Formation (Lower Cambrian), South Australia

ABSTRACT Usually well preserved fluidization pillars and sand filled fluidization pipes occur within submarine channel sands of the basal Uratanna Formation (Lower Cambrian) in the Adelaide Geosyncline of South Australia. The morphology of these structures reflects complex lateral and vertical movement of fluids during liquefaction and dewatering. Fluidization pipes acted as conduits for highly concentrated, upward directed fluid flow. The formation and maintenance of these pipes was dependent upon the development of a pipe wall composed of clay plugged fine sand. Formed during initial fluidization, this lining acted as a permeability barrier, confining and concentrating fluidized flow within the pipe. Each of the pipes is surrounded by a cylindrical fluidization halo in which leakage through the pipe lining produced partial fluidization of the surrounding sediment. Fine scale structures within these haloes indicate that fluids flowed radially and upward out of the fluidization pipes at an acute angle. These fluids merged with and influenced the orientation and size of adjacent fluidization pillars. The fluidization pipes of the Uratanna Formation may represent unusual preservation of the unstable fluid flow conditions that occur during incipient fluidization of sand beds.     

大牛地气田水平井通井卡钻处理

卡钻的处理方法主要有：通过施加外力如上提、下放钻具转动转盘使钻具恢复自由状态;通过调整钻井液性能、打稠塞、注酸、注解卡剂、反循环等方法使被卡钻具与井壁之间的填充物转移或者破坏;通过反丝钻具打捞甚至套铣起出被卡钻具。大牛地气田DPT-305水平井通井过程中发生一起严重的卡钻事故。通过重浆+清扫液、注酸、注解卡剂、环空憋压等方法处理被卡钻具与井壁之间的填充物;通过固定转盘上下活动来对被卡钻具施加扭矩;倒扣等方式处理这起卡钻事故,最终解卡。总结了事故的成因,分析了处理过程的得失,为以后处理此类事故积累了经验。     

径向水力喷射钻井技术在煤矿注浆孔中的应用

采用石油行业径向水平喷射钻井技术在煤矿注浆堵水方面可实现水平定向射流成孔,在薄层灰岩、奥陶系灰岩承压含水层中寻找沟通裂隙,尤其在直井或分支井段较小漏水的情况下可进行多分支喷射,还可以加适量盐酸、酸化缓蚀剂进行局部酸化沟通裂隙,压裂地层,从而降低注浆压力,提高注浆堵水效果。径向水力喷射钻井在峰峰集团梧桐庄矿9号注浆孔应用取得了一定的成效。该技术也可作为地热井增大水量的一种手段。     

河南某地热井管挤毁事故分析及处理

中原地区地热井成井中使用的过滤管大多为桥式过滤管,在下管过程中,如果泥浆性能不均匀或者管内灌浆不及时等,使得管内外压力不平衡,而当该压力超过过滤管的抗挤强度后就容易造成过滤管挤毁事故的发生。针对河南某地热井下管中发生的过滤管挤毁事故,分析造成该类事故的原因及在成井过程中应注意的问题。     

Applicability of a Backprojection Algorithm to Reconstruct Images of Subsurface Horizontal Planes for Laboratory Experiments in Electrical Resistance Tomography

This paper describes the use of a backprojection algorithm to reconstruct subsurface images of the electrical resistivity in horizontal planes parallel to the surface. The algorithm can be applied to detect buried objects such as tanks or pipes and possible leakages from them. Two imaging strategies are compared: juxtaposition of vertical planes, and 3D reconstruction from the sensitivity matrix corresponding to the entire volume whose surface is explored. The electrode arrays used for voltage measurement are the dipole–dipole array and a modified Schlumberger array. A personal computer controls current injection, electrode switching, and voltage detection. The system injects 1 kHz, 20 V peak-to-peak square waveforms, thus avoiding electrode polarization effects. Experimental laboratory measurements show that the algorithm detects localized objects such as an insulating sphere and a conductive cylinder immersed in water. Furthermore, covering half of the cylinder by a rubber sleeve to simulate a nonconductive leak, yields a distinct image for the leak. The backprojection algorithm does not need any regularization parameter and it is very fast in inverting the sensitivity matrix because it approximates the inverse matrix by its transposed. The dipole–dipole array usually yields a lower overall pixel error than the modified Schlumberger array but both allow the detection of simulated underground leaks.     

袖阀管注浆工法在国内工程施工中的应用

介绍了袖阀管注浆工法的特点,主要技术要求和施工工艺流程,以及该方法在国内注浆加固,防渗,堵漏施工中的应用实例。     

深厚软土地区某厂房基础沉降原因分析和对策

某厂房由于软土排水固结和地面回填堆载产生地面沉降过大，针对各部位荷载与地质条件的不同情况，分别采用了袖阀管静压注浆和锚杆静压桩托换技术对软土地基进行加固处理，取得了良好效果。介绍了袖阀管静压注浆法和锚杆静压桩托换法的技术特点、加固机理及施工工艺。     

Three‐dimensional responses of buried corrugated pipes and ANN‐based method for predicting pipe deflections

This study investigated localized responses, such as circumferential stresses, on corrugation and pipe deflections. Also, this study examined the effect of corrugation geometry on the overall and localized response of corrugated pipes with refined three‐dimensional modeling of the entire soil–pipe interaction system, including corrugation. To investigate the availability of the traditional two‐dimensional method, the results from the three‐dimensional finite element method (FEM) were compared with those from the two‐dimensional FEM. The soil–pipe modeling techniques of this study were verified by comparing the FEM results by Utah State University and analytical results. An artificial neural network (ANN)‐based model to predict vertical deflections of buried corrugated pipes was developed to overcome the shortcomings of existing methods and obtain results that are close to the level of accuracy of FEM results. In order to train an ANN, analyses on a large amount of data were executed with various standardized pipe geometries and burial depths regulated by the Korea Highway Corporation using the two‐dimensional FEM verified in this study. The widely used back propagation algorithm was adopted. The ANN‐based model developed in this study was shown to be an effective tool by comparing the results with test data and sensitivity analyses were executed based on the data from the developed ANN. Copyright © 2010 John Wiley & Sons, Ltd.     

岩溶地区桥墩桩基钢护筒变形加固处治技术

本文以大王山矿坑工程中桥墩桩基钢护筒变形事故为研究背景,通过理论分析与现场实际相结合,展开了岩溶地区桥墩桩基础钢护筒变形处治与力学分析研究,其主要研究结论如下：（1）桩钢护筒变形处理采用气切割钢护筒和千斤顶孔内校正变形法,并以内支撑、C30高流态混凝土填充、注浆加固辅佐;（2）型钢内撑采用80 mm×80 mm×2.5 mm矩形钢管,环向布置分为3个三角形,竖向设置间距以0.5 m为最优;（3）桩周预埋8根注浆小导管以及4根小导管向上倾斜插入溶洞内注浆,注浆加固效果明显;（4）气切割法逐层切割,每层切割高度50 cm,环向划分为3块进行切割,并用2 cm厚钢板弯制成2个半圆,焊接封闭成环。本项目研究内容可为类似工程提供理论和实践支持。