r淤泥质地层小关净距隧道下穿建筑物施工关键技术

1、rapid development of the market economy environment to explore public servants duty consumption monetization reform has provided a good foundation. the socialization of rear service work has been launched, and rapid progress in some places and departments, duty consumption monetization of carrier an

2、d approach to management has been resolved. third, in recent years, exploring the monetization of duty consumption has made some progress, have gained some experience and can provide reference to the comprehensive reform of the system of public servants duty consumption further. implementing an hone

3、st canteen, standardize official entertaining management; enhancing the telecommunication expense management; elimination of county travel and countryside subsidies; research village officials capitalization management of corporate spending, and so on. finally, group .18 session to be held in beijin

4、g from november 9, 2013 to 12th. 35 years ago blew the third plenary session of the reform and opening up in the spring breeze, changed, affect the world; today, 35 years later, in the eyes of the nation and the world expect, again to reform mark china, ushered in the 18 session. xi general secretar

5、y pointed out that chinas reform has entered a crucial period and the sham shui po district, must be based on greater political courage and wisdom, lose no time in deepening reform in important fields. dares to crack a hard nut, dares to question the rapids, which dares to break the barrier of ideas

6、, and dare to benefit cure barriers. deepening reform and opening up is on schedule to achieve institutional safeguards of the moderately well-off. under the five in one the general layout of socialist modernization requirements, 18 session of the decision was a five in one and the improvement of ov

7、erall scheme of reform, will promote an integrated and coordinated economic, political, cultural, social and ecological civilization construction of the five reforms and the partys construction in the area of institutional reform. the five in one programme is to achieve a comprehensive reform of ins

8、titutional guarantees for objectives of build a well-off society, the smooth progress of the construction of a well-off society and reform the objectives of the programme. one, holding time and place importance on november 9, 2013 to the 18 session of the 12th beijing since 1978, 35, have been 7 ple

9、nary session, each time on major issues of political and economic life of the country has made important deployment. in accordance with prc political practice, often at every session of the cpc central committee in a plenary session was held immediately after the partys congress, on the theme person

10、nel, discussing election centrals top leaders, such as the election of the standing committee of the political bureau, through the central committee members, decisions, such as members of the central military commission. the second plenary session, is held in two sessions before the general election

11、, mainly to discuss a new state personnel issues. but by the third 淤泥质地层小净距隧道下穿建筑物施工关键技术摘要：本文主要通过工程实例阐述淤泥质地层小净距隧道下穿既有建筑物施工关键技术和控制要点。关键词：淤泥质地层；小净距隧道；下穿既有建筑物；关键技术abstract: this paper mainly through engineering examples of silt quality of a material of small interval tunnel in adjacent buildings under

12、construction key technology and control points.keywords: silt quality of a material layer; small interval tunnel; in both under buildings; key technology中图分类号：tu74文献标识码：a 文章编号：0引言某地铁区间隧道下穿既有地下通道段属于多条小间距隧道并行穿越既有建筑物的工程类型。施工中以设计方案为依托，通过对施工工艺、支护参数进行调整改进，有效的控制了隧道结构及周边建筑物沉降变形，工程如期顺利完成，取得了良好的社会和环境效益。文献1采用数

13、值模拟方法在理论上对群洞施工步序、步距的合理性进行了研究分析，文献2-6根据工程实例提出群洞施工的合理工序和关键技术措施，文献7-8分别采用数值模拟和现场实测的方法对群洞施工过程中洞内外沉降情况进行了分析总结，本文编写过程中涉及的相应内容有所参考借鉴。1工程概况某地铁区间隧道为分离式单线隧道，沿城市主干道下方布设，在距区间隧道东端头65米位置设置一座临时竖井和横通道。横通道以东段，由三条小间距隧道组成，分别为区间左、右线隧道及与其对接的地铁车站站1号风道，三条隧道平行布置。三条隧道净距34米，下穿既有过街道段长约为13.5米，隧道结构顶距离既有通道底板净距1.2米。图1隧道与过街通道相互关系剖

14、面图2地质特点隧道穿越-2b4软流塑地层。该地层富水饱和，蠕动性强，土层自稳能力极差。开挖支护过程中极易发生涌泥、涌水、坍塌现象。原过街通道施工对地层已有干扰，破坏了原有软流塑地层结构。正线隧道施工时属二次扰动，地层应力释放和重分布更为明显，地层变形造成的沉降比其它地段更加敏感。在正线隧道施工完成后，进行1号风道施工时造成地层的再次扰动，地表以及建筑物沉降控制难度极大。3施工关键技术3.1超前大管棚施工图2管棚施工示意图原街通道围护桩把该段隧道分成了过街通道以西、下穿过街通道段及过街通道以东三个部分，因此大管棚的施工也被分成三个循环区段（参见图2）。3.1.1第一循环（过街通道以西段）利用已经

15、施工的横通道空间施作第一循环大管棚，管棚直径121，由于过街通道同隧道斜交，每一根管棚的长度都不一样，同时考虑第二个循环管棚工作室的施工，按照最短的一根管棚来计算管棚施工的仰角，采取跟管钻进工艺，终孔在过街通道西侧围护桩面。3.1.2第二循环（下穿过街通道段）利用管棚工作室从西往东钻进施工，管棚直径146，由于过街通道同隧道斜交，每一根管棚的长度都不一样。采用金刚钻头开孔破过街通道西侧的围护桩，然后跟管钻进，终孔在过街通道东侧围护桩面。随后进行注浆。在施作管棚前采用钢花管对通道下方碎石层进行注浆加固，提高碎石层和土层稳定性，减小开挖对通道下1.2m土层破坏，并对通道底部含水碎石垫层施作引水钢管

16、排水，该段初支完成后利用小导管径向注浆对上方过街通道结构补浆回填，防止通道结构后期下沉，影响隧道和通道结构安全。3.1.3第三循环（过街通道以东段）受过街通道底板高度的限制，无法施作过街道以东段第三个循环大管棚的工作室。因此，第三个循环管棚沿用第二循环的工作室，对第二循环的146管棚采用岩心钻扫孔、洗孔后，作为第三循环121管棚的导向管从中继续往前钻进布设，这样既可以有效解决采取金刚钻开孔穿过围护桩并在穿孔后继续采用跟管钻进的问题，另一方面套管施工提高了下穿过街道段的管棚刚度。3.2 全断面劈裂注浆为了有效控制注浆压力对隧道结构、过街道及地表管线的影响，劈裂注浆采用hsc超细水泥浆。另采取多开

17、孔、小浆量的注浆工艺，通过加密掌子面布孔、减少单孔注浆量，以达到均匀改良地层、降低注浆压力的效果。劈裂注浆孔的断面布置情况见图3。图3 劈裂注浆布孔图3.2.1注浆参数（见表1）3.2.2 浆液配比周边孔采用超细水泥浆，该种浆液具有早强、高结实率、可注性强等特点，尤其在粉土、淤泥质等地层中有极好的渗透性，且对地层扰动较小。其余内圈孔仍采用普通水泥水玻璃双液浆。超细水泥浆水灰比1：11.2，普通水泥浆水灰比1：1，水泥浆：水玻璃1：0.81，水玻璃稀释浓度205be。3.2.3 注浆顺序对原设计注浆顺序进行调整。采取由外而内、自下而上的施工顺序，每圈采取隔一注一的方式跳孔注浆。图4劈裂注浆顺序图

18、3.2.4 注浆工艺1）采用30cm厚c20网喷混凝土止浆墙，6钢筋网，网格间距1515cm，按普通喷混凝土工艺完成。2）采用钻机成孔，钻孔精度控制在1%以内。3）成孔后插入42mmpvc袖阀管。4）下管完成后，孔口50cm深度范围内采用双快水泥进行密封。凝固后，向注浆管内注入套壳料对管壁空隙进行填充，单孔注入0.51.0m3浆液，完成后用清水洗孔。5）待pvc管与孔壁之间固结体达到一定强度后，在pvc管内插入注浆芯管（含止浆塞）进行分段注浆。袖阀管管壁溢浆孔布设间距40cm，且用橡皮套包裹，注浆时压力使浆液顶开橡皮套，进入土体产生劈裂效果，并沿着裂缝扩散，扩散范围受注浆压力、时间、浆液配比、

19、土层特征等因素的影响；停止注浆时，橡皮套再次收缩包裹溢浆孔，防止浆液倒流。6）采用后退式注浆，即从注浆管最底部开始注，边注边拔芯管，每次拔管长度1米。7）注浆完成后，清洗管内残留浆液，以便于第二次重复注浆。8）按定量定压相结合的原则，以定压注浆为主来作为注浆结束标准：当注浆压力稳定上升，达到设计终压；浆液注入量达到设计值80%以上，并持续稳定10分钟以上后，不进浆或进浆量很少时，即可停止注浆，进行封孔作业。3.3 洞内径向注浆考虑1号风道开挖范围内土体为淤泥质粉质粘土，且经左右线隧道施工扰动后产生液化。为降低风道施工对左右线隧道的影响，待左右线隧道初支施工完毕后，在隧道内对其周边土体进行径向注

20、浆加固，形成加固帷幕（见图5）。图5径向加固注浆示意图3.3.1注浆材料注浆管采用32无缝钢管加工，l4m，顶端呈封闭尖锥状；沿管身500mm间距梅花型布设逸浆孔，孔径5mm，尾端1m不设孔；注浆管采用风钻成孔后顶入，孔位环、纵向布设间距0.91.0m。3.3.2浆液配制浆液采用超细水泥单液浆，水灰比1：1。3.3.3 注浆控制及注浆结束标准径向注浆以压力作为注浆结束标准。注浆时，拱部注浆压力宜控制在0.4mpa以内，边墙注浆压力控制在0.8mpa以内，防止压力过大造成地表隆起及过街道结构变形。3.4下穿过街道段截桩施工在隧道开挖过程中须过街通道围护桩进行破除。为防止破桩影响上部结构安全，保证

21、结构受力稳定并达到快速施工目的，现场采用型钢拱架代替格栅，型钢紧贴密排，在破除桩体时形成连续纵梁结构，完成过街通道桩体受力转换，防止破除桩体后发生桩底失稳危及过街道安全。4施工监测及结果评价施工期间隧道结构稳定，未出现突泥、涌水、路面坍方等险情。地表及管线、地下过街道结构均稳定，未发生隆起变形或开裂现象。施工期间监测数据统计及分析如下：1)地表及管线沉降左、右线开挖过程中引起地表沉降最大值分别为49.3mm和39.1mm，点位均处于隧道中线上。风道开挖引起地表沉降最大值12.9mm，点位也处于风道中线上。供水管线最大沉降量为21.1mm。2)隧道内沉降、收敛及通道沉降群洞段开挖完成后，隧道内拱

22、顶最大沉降16.5mm，收敛1.14mm；地下过街道最大沉降量16mm。3)风道开挖期间，左右线隧道内沉降、收敛监测数据未发生明显变化，隧道结构稳定。由此分析，各隧道开挖范围内及周边软流塑地层经注浆加固、加强支护措施后，在开挖过程中的群洞效应明显降低，结构变形均处于稳定、可控状态。而上层未加固的软流塑地层经失水、施工扰动后发生蠕变、液化流动以重新达到平衡状态，从而引起相对较大的地表沉降。若具备场地条件，能够在路面上对隧道上层土体实施注浆加固，则地表沉降控制效果将更加理想。5结论与讨论上述技术措施是建立在对淤泥质地层特性有一定的认知和了解的基础上，同时结合施工中总结的经验，对地层加固、管棚施工等

23、关键技术进行改良，并通过合理的施工组织安排，确保了隧道施工安全和周边环境的安全正常，解决了软流塑淤泥质地层小间距并行隧道近距离下穿既有建筑施工安全风险，取得了良好的经济、社会和环境效益。1)管棚施工工艺改进通过对管棚施工工艺的改进，首先增强了下穿既有结构段的超前支护强度，较原设计的密排超前小导管支护措施有更可靠的安全性；其次，二次套打的121管棚在穿过既有结构底部后可直接延伸至开挖终点里程，代替了设计图中的60中管棚施工，既增强了超前支护强度降低施工风险同时也节省了中管棚施工循环时间，加快了施工进度，具有一定的间接经济效益。2)注浆工艺改良施工中采用了劈裂注浆和径向加固注浆两种不同的注浆工艺，

24、对这两种工艺的改进主要是基于有效控制注浆压力，防止造成既有建筑物、已成型隧道开裂变形的目的。采用超细水泥浆代替普通水泥-水玻璃浆液很大程度上增加了成本的投入，但地层加固的效果有了明显提高，施工过程中对周边环境的影响也得到了很好的控制，具有良好的社会和环境效益。【作者简介】江天堑（1975年5月），安徽黄山人，工程师，现工作于中铁隧道集团二处有限公司，主要从事城市地铁工程施工管理。参考文献1 庄宁，廖少明，孙忠成等.大跨度小净距群洞隧道施工方案优化研究j.地下空间与工程学报.96-100。2 杨宏射.地铁浅埋群洞施工工序与关键技术j.城市轨道交通研究.70-72。3 郭龙，刘牧宇.浅埋暗挖群洞法

25、施工中结构受力的合理转换j.铁道建筑.25-27。4 仝学让.浅埋大跨度群洞隧道施工技术j.安徽建筑.92-94。5 陈世权，王俊生.小净距大跨度隧道的施工技术j.工程质量.35-38。6 董惠定，李兆平.北京地铁车站暗挖施工方法比较与评述j.现代隧道技术,2004年增刊：101-105.7 刘成伟，刘招伟，余永强.某地铁车站群洞法施工地表沉降监测分析j.西部探矿工程.138-140。8 余永强，文广超.地铁车站“群洞法”施工对地表沉降影响的数值模拟j.华东公路.84-87。注：文章内所有公式及图表请以pdf形式查看。plenary session, each session of the c

26、entral committee of national institutions and personnel problems have been arranged, you can concentrate on national development and reforms. previous plenary session is often branded with a central leading collective, often by looking at the third plenum of the initiative to found the current centr

27、al leadership collective governance characteristics. from the analysis of the process of economic reform in china, plenary session, 12 session, 14, 16 plenary session have programmatic meaning, respectively, marking the four stages of chinas economic reform, and that the start-up phase of reform, re

28、form, construction phase and perfecting the socialist market economy framework stage of socialist market economy. previous plenary session topics proposed to the third plenary session of taking class struggle as the key link, shifted to socialist modernization; 12 session marked the change from rura

29、l to urban, established with public ownership as the foundation of a planned commodity economy; 13 session at a time when both the old and the new system change, governance and rectify the economic order; 14 . fair and efficient and authoritative socialist judicial system, safeguard the peoples inte

30、rests. legal authority to uphold the constitution, deepening the reform of administrative law enforcement, ensure that the right to exercise judicial power independently and impartially according to law the prosecution, perfecting the running mechanism of judicial power, improve the system of judici

31、al protection of human rights. plenary session, affairs the right to adhere to the system, and let the people authority to let the power run in the sun, is shut up in a cage of the system power policy. decision science, implementation should be constructed strong, supervise the running of powerful system, improve the system of punishing and preventing corruption, promoting political integrity, and strive to achieve cadres honest and government