爆破条件下基坑围护结构渗漏防治施工方法

地下连续墙存在局部渗漏是基坑开挖中不可避免的问题,我国东南地区在对基岩及花岗岩微风化带进行爆破开挖施工时,常常引发地连墙开裂渗漏。而一般渗漏防治方法不适用于这些地区上软下硬的特殊地层地质。因而,本文针对爆破条件下基坑围护结构渗漏防治问题,提出一种先分区分层爆破开挖,再采用高压旋喷技术和双组分聚氨酯高聚物材料注浆技术相结合进行裂缝堵漏的施工方法。同时不断调整爆破参数,使爆破施工精确化。不仅有效防治了地下连续墙的渗漏问题,也保证了基坑开挖高效低耗。     

上软下硬地层中地下连续墙快速成槽技术

广州地铁18号线横番区间2号中间风井位于南沙区东涌镇细沥村,地质情况复杂,上软下硬,地下连续墙入岩深度为8～20 m,微风化花岗岩最大饱和抗压强度为143.5 MPa.地下连续墙成槽难度较大,双轮铣单独成槽效率极低且成本极高,通过采用冲击钻对硬岩进行引孔,减少双轮铣铣硬岩工程量,增加临空面,可有效提升双轮铣成槽效率,降低成本.     

大起伏岩面地下连续墙成槽施工技术

武汉轨道交通21号线百步亭花园路站地下连续墙墙底灰岩面起伏大,地下连续墙嵌入灰岩不少于1 m。由于大起伏岩面地下连续墙的施工难度大,经工法比选,决定采用超前地质钻勘探和冲抓结合法进行成槽施工。实践表明,该方法有效地解决了大起伏岩面地下连续墙成槽难题,也有效地避免了钢筋笼割除的问题;同时能保证多机械平行施工,大大提高了成槽效率,缩短工期,减少地下连续墙施工成本。     

深圳地铁田贝站入岩地下连续墙施工技术

深圳地铁3号线田贝站入岩地下连续墙采用抓斗成槽机配合冲桩机施工方案.施工中地下连续墙导墙进入岩层时变形过大,将原设计L形导墙改为C形导墙,保证了导墙正常施工;斜岩面导致地下连续墙成孔垂直度出现较大偏差,将槽厚增加至1.2m,改用直径1.2m重锤成孔顺利解决该问题;成槽过程中通过调整操作工艺和施工机具解决卡锤问题;采用泥浆净化机配合潜水泥砂泵清槽,提高了工效且保护环境.     

软土-花岗岩地质条件下地下连续墙施工技术

珠海隧道东岸工作井及挂锭角以西明挖基坑地下连续墙施工前期,采用“成槽机+冲击钻”施工工艺,在成槽过程中,出现偏孔,且单幅槽段成槽周期达40 d,依然无法成槽,严重影响施工工期。为保证整体项目施工工期,改变地下连续墙施工状况。通过对地质补勘,对地下连续墙入岩深度设计优化,并结合类似工程实践经验,优化地下连续墙成槽机械设备选型。总结出在软土-坚硬花岗岩地质条件下,采用“旋挖钻+双轮铣”施工工艺。首选旋挖钻作主孔引孔,后采用双轮铣铣削成槽,从而解决了硬岩及斜岩地层中地下连续墙成槽困难的问题。同时地下连续墙施工效率得到了极大的提升,保证了地连墙成槽质量,取得了良好的经济效果,积累了临山临水地域软土-花岗岩地质条件下的地下连续墙施工经验。     

西部城市轨道地下连续墙入岩成槽施工工艺改进

在昆明市盘龙区世博停车场内地下连续墙施工中,采用了中风化岩层地下连续墙入岩成槽施工工艺,该施工工艺进行了改进,在不增加机械设备的情况下极大地改善了入岩段连续墙偏孔的问题,且缩短了成槽时间,效果显著。通过对相同地质条件下两种施工工艺进行了数据上的比对分析证明,改进后施工工艺具有推广应用价值。     

复合地层超深地下连续墙快速成槽施工技术研究

地下连续墙施工中,一般采用冲击钻+成槽机施工方法,但该方法施工效率低,所需工期时间长,易造成成槽机的磨损损坏,鉴于此问题,以某项目超深地下连续墙施工为依托,研究复合地层超深地下连续墙快速成槽施工技术,并提出了将“钻–抓–铣”相结合,通过增加引孔设备,根据槽端划分,在两个铣轮中间位置引孔至墙底标高后,先采用液压抓斗,抓槽至岩面标高后再用双轮铣。经应用证明,该组合式成槽方法,提高了地下连续墙成槽施工的效率和成槽质量。     

某嵌入岩层的地下连续墙成槽施工技术

该文通过某钢厂4300mm宽厚板轧机工程漩流池地下连续墙施工实例,介绍在中、微风化粉砂岩层中,采用液压抓斗结合冲击钻机并利用优质泥浆护壁的成槽施工技术,解决了在该类中、微风化粉砂岩中的地下连续墙的成槽施工难题。     

地下连续墙接头病害的跨孔雷达检测方法

地下连续墙的接头是基坑围护结构的薄弱部位之一,在施工中容易出现渗漏、夹泥、开裂等病害,危害基坑本身和周边环境的安全。为实现在基坑开挖前对病害进行检测,针对跨孔雷达检测方法展开了研究,分析了电磁波在地下连续墙内的传播特点,指出可采用零高差测量对病害进行快速定位,然后实施多高差测量确定病害的具分布形态。基于电磁波时域有限差分法,通过数值仿真模拟了跨孔雷达对地下连续墙接头渗漏、夹泥和开裂病害的探测,分析了各类病害的跨孔雷达数据特征。利用跨孔雷达方法对某地铁车站基坑地下连续墙进行探测试验,准确找出了地下连续墙接头夹泥及其分布范围,验证了跨孔雷达方法的有效性。     

嵌岩地下连续墙冲孔槽段施工新工艺

浙江国华宁海电厂二期雨水泵房深基坑设计采用嵌岩地下连续墙挡水支护结构,其成孔灌注成为施工难题,采试用冲孔槽段施工新工艺,成功完成该嵌岩地下连续墙施工。     

不良地质条件下地下连续墙成槽施工技术

在天津市不良地质条件下,某深基坑61m超深地下连续墙施工过程中,通过对试成槽试验结果的分析,制定了槽壁两侧深层搅拌法加固控制上部淤泥质土层稳定,增大槽内护壁泥浆比重控制下部砂层稳定以及调整成槽工艺等措施。结果证明,采取的技术措施取得了较好的成槽效果,为保证地下连续墙的施工质量打下基础。     

Geological difficulties and countermeasures for socket diaphragm walls in weathered granite in Shenzhen,China

In Shenzhen, a complex series of folds and fractures, and intensive metamorphism took place during the pre-Caledonian, Caledonian, and Hercynian to Indosinian orogenies. Then, Yanshanian orogeny, with the most tectonic movement, occurred. Strong invasive activity of granitic magma, a massive blowout of acidic volcanic rock, and magmatism-related mineralisation are the features of Yanshanian orogeny. Moreover, deep faults were also developed and wide folds were formed. A large amount of granite rock was formed from the Yanshanian orogeny in Shenzhen. The outcrop area of the granite in Shenzhen reaches 760 km², almost covers 50 % of Shenzhen land area. Granite is primarily susceptible to chemical weathering. Though weathered, granite and solitary granite boulders are of high uniaxial compressive strength (UCS). The weathered granite may be covered by Quaternary soil with low shear strength, such as backfill, sand, silty clay, and clay. The thickness of the Quaternary soil ranges from 0 to 40 m. Socket diaphragm walls are usually adopted during deep excavation construction in Shenzhen for their safety and low impact on the surrounding environment. When the excavation depth is increased, the socket diaphragm walls are embedded in weathered granite to a depth of between 3 and 10 m. However, the traditional socket diaphragm wall construction is only viable in soft ground, as it is not practical to penetrate hard weathered granite. As a consequence, difficulties arise during construction in the Shenzhen region, such as difficulty in breaking down the rock, socket diaphragm wall collapse and leakage. To solve these construction problems, countermeasures, such as monitoring, heavy hammer dropping, smooth blasting and a modified slurry, are proposed in this study. It can be concluded that the heavy hammer dropping method should be chosen to deal with weathered granite with a UCS of less than 50 MPa and the smooth blasting method should be adopted to deal with weathered granite with a UCS of more than 50 MPa. A case study of a metro station excavation using the smooth blasting method in Shenzhen is also introduced. The successful construction of the socket diaphragm walls demonstrates the applicability of the smooth blasting method.     

南京河西地区超深地下连续墙施工技术

地下连续墙施工工法已成功应用于多个城市地铁建设施工之中,并取得了显著的施工效果。在南京地铁二号线中~元区间修复工程中,河西地区粉砂性土层中首次成功施工了深达47m,厚度1m的地下连续墙,为河西地区地下连续墙施工积累了很多宝贵经验。文章以南京地铁二号线中～元区间修复工程为依托,主要从地下连续墙成槽设备、接头形式、成槽工艺、接头处理以及泥浆处理等方面介绍了南京地铁二号线中~元区间的地下连续墙施工技术。     

超深地下连续入岩导墙施工要点浅谈

通过武汉市轨道地铁车站地下连续墙施工实例,探讨了导墙施工技术,重点从施工工艺、质量保证措施以及连续墙成槽施工等几个方面阐述了超深地下连续入岩导墙施工要点,旨在为类似工程提供参考。     

地下连续墙成槽施工引起土体位移的三维数值分析

采用三维有限元法模拟了地下连续墙单个槽段的成槽施工,研究了泥浆比重、成槽宽度、成槽深度、及成槽厚度对槽壁水平位移及地表沉降的影响。结果表明:槽壁的水平位移和地表沉降对泥浆比重和成槽宽度的变化较为敏感;当成槽深度增加到一定程度后,再增加成槽深度,对槽壁最大水平位移和最大地表沉降的影响很小;成槽厚度的变化对槽壁的水平位移和地表沉降的影响较小。     

超厚砂层超深地下连续墙成槽综合技术

针对吹填砂海域的独特地质条件阐述了曹妃甸吹填砂海域超厚砂层超深地下连续墙成槽技术,从设备选型、地连墙的设计、泥浆的配制及循环管理等几个环节采取相应的措施,确保地下连续墙在保证质量的前提下,能安全、高效的完成。     

Ground–liner interaction in rock tunneling

Tunnel constructions are gradually increasing because of the development and upgrade of infrastructures such as highway, subway, railway, and many other facilities. Most of tunnels are excavated either by using drilling and blasting or by using tunnel excavation machines such as TBM (tunneling boring machine) or Shield. NATM (new Austrian tunneling method) is one of most frequently used tunneling methods and it uses drilling and blasting to excavate a tunnel in rock. While tunnel excavation using TBM or Shield machines produces quite a regular and smooth tunnel excavation surface, the tunnel excavation using drilling and blasting results in a very irregular and rough excavation surface. The stress behavior in a shotcrete tunnel liner installed along the excavation surface is very dependent on the surface status and tunnel engineer should consider the surface condition for the design of a shotcrete tunnel liner.Numerical analyses are conducted to investigate the effect of the irregularity of tunnel excavation surface on the response of the shotcrete tunnel liner. For the investigations, the controlled parameters include the irregularity of the excavation surface, the stiffness of the surrounding ground, and the coefficient of earth pressure at rest. The investigations show that the response of a shotcrete tunnel liner is highly dependent on the parameters and for the same earth pressure condition the effect is more evident when the irregularity is more severe and the surrounding ground is less stiff.     

岩巷掘进准直眼掏槽爆破新技术应用实例分析

 为了提高岩巷掘进速度,克服直眼掏槽和斜眼掏槽的不足,根据岩石爆破理论,提出一种新的掏槽方法--准直眼掏槽方式。该掏槽方式突破传统掏槽设计,主掏槽眼稍微倾斜(准直眼),槽底炮孔间距较大,次掏槽眼垂直于自由面。与现有掏槽方式相比,该掏槽方式具有以下特点：准直眼孔底间距大,可杜绝穿孔现象;采用合理间隔时间进行分层分次爆破;中心辅助直眼与两侧对称的准直眼互相配合,结合直眼掏槽和斜眼掏槽各自的优点;形式简单,易操作;槽腔大,效率高,成本低。基于爆生气体的准静态理论和岩石力学的极限平衡理论,分析准直眼掏槽槽腔形成过程。为了优化准直眼掏槽参数,进行大量的现场掏槽试验,从而确定不同爆破条件下的准直眼掏槽炮孔的布置方式、深度、倾斜角度、间距、装药量和微差起爆间隔时间等技术参数。施工中采取以长度定角度的方法可满足该掏槽方式对准直眼角度的严格要求。实践表明,在煤矿岩巷掘进中使用准直眼掏槽方式,能够取得良好的爆破效果和显著的技术经济效益。     

Development of low noise and vibration tunneling methods using slots by single hole continuous drilling

We have recently developed a new continuous hole drilling method as a rock fracturing method in hard rock tunnel excavation and as a free face forming method to be used at the time of controlled blasting excavation. In this paper, we overview the continuous hole drilling method and explain the tunnel excavation by the rock fracturing method and the controlled blasting by using this method.     

应用光面爆破技术提高隧道开挖质量

介绍南坪隧道出口段开挖施工中应用光面爆破技术所涉爆破器材，爆破参数，掏槽方法，炮眼布置的选用和取值，以及实施光面爆破设计时针对不同的围岩状况和爆破效果对掏槽方法和相关参数的调整情况。并阐述了光面爆破技术应用重点。指出技术人员必须职累各种不同情况下不同岩体结构所采用的各项爆破参数，并运用数理统计方法，从理论上加以分析归纳总结，才能为更好地推广应用光面爆破技术奠定基础。