管幕冻结施工工法研究与应用

发布时间：2018-05-03 06:30

本文选题：管幕冻结工法 + 曲线管幕　；参考：《长安大学》2015年博士论文

【摘要】：随着我国工程建设的深入推进,出现了一些复杂工程如高速公路下穿正在运营的铁路线、不停航跑道下修建地下通道、高速公路或城市道路下穿敏感建筑等。这些工程对自身施工安全和地表沉降控制提出了更高要求,管幕冻结法为解决此类复杂工程问题提供了一种新的技术思路和途径。管幕冻结法是利用顶管设备将钢管管节顶入土体中,各单管间的空隙采用冻结的方法进行封闭止水,在管幕及冻结圈组成的支护体系下进行土体开挖的一种施工方法,是针对曲线管幕在管幕法的基础上而提出的。该工法体系中,由顶管形成的管幕作为结构体承受主要荷载,冻结起到封水作用,防止管间的水土流失。本文以正在建设的港珠澳大桥珠海连接线项目为依托,结合拱北口岸暗挖段工程实际,采用室内模型试验研究了单根顶管管节偏角与管节应力变化规律,并采用室内模型试验和数值分析研究了管幕顶管群管间的相互影响,为曲线管幕的形成提供参考。研究了冻结止水帷幕在积极冻结期和维护冻结期的冻结效果,并对冻胀变形的影响进行了数值模拟计算分析,取得以下主要成果:1、管幕冻结法工法在技术上是可行的,可为复杂条件下的暗挖施工提供一种新的思路。2、顶进力按照经验公式计算时,应充分考虑各种因素对顶进力的影响。在曲线顶进过程中,顶进力的传递呈不对称分布,管节应变沿轴线基本呈减小的趋势,且管节会存在一定的偏转。3、通过相邻顶管相互影响的研究结果表明,后顶顶管会对先定顶管产生一定的影响:顶管所产生的沉降槽随后顶管的顶进由先偏向顶顶管的上方向两管中间偏移,两顶管间的土体出现较大的屈服,后顶顶管会在先顶顶管上产生一定的附加作用力。通过控制顶管施工顶进参数控制、及时测量纠偏,管幕顶管间的相互影响作用可有效降低,可保证管幕的形成。4、在积极冻结期,仅开启圆形冻结管可以实现顶管管节的封水作用,但形成设计的冻土厚度需较长时间。异形加强冻结管可明显提高冻结效果。因此,在工程应用中建议在积极冻结期采用圆形冻结管和异形加强冻结管同步开启方案。对长距离水平冻结,建议采用分段冻结方案。5、在维护冻结期,为减少对冻结效果的影响并利于开挖断面的施工作业,开挖断面内空气温度宜控制在25℃。开挖断面的风速对冻结效果影响不显著,对开挖断面的通风无需要求过严。6、限位管的开启对冻结效果影响非常显著,限位管的开启可有效控制冻土的厚度。限位管内流体的温度对冻结效果影响较大,为避免洞穿现象并有效限制冻土厚度,限位管内流体的温度宜为15℃左右。7、地表最大隆起量、最大水平位移、隆起影响范围及水平位移影响范围随冻土壁厚度的增加而线性增大,管幕上端、侧端顶管的位移随冻土壁厚度的增加而线性增大。因此,在工程中必须对冻土壁厚度加以控制,以免对周边环境产生较大影响。8、地表最大隆起点和地表水平位移最大点的位置几乎不随冻土壁厚度的变化而变化,最大隆起点总是发生在地表竖直对应暗挖段中心的位置,最大水平位移总是发生在管幕侧壁横向向外5m左右所对应地面的位置附近。利用这一规律,结合地面变形监测数据,可以更有针对性的来控制地面变形。
[Abstract]:With the deepening of the construction of China's engineering, some complex projects, such as the railway lines running under the freeway, the underground passage under the runway, the sensitive buildings under the highway or the urban road, have been put forward. These projects put forward higher requirements for the safety of the construction and the control of the ground settlement, and the freezing method of the pipe curtain is solved. This kind of complex engineering problem provides a new technical idea and way. The freezing method of pipe curtain is a construction method for the excavation of soil under the supporting system composed of pipe curtain and freezing ring. The curtain is put forward on the basis of the pipe curtain method. In this system, the pipe curtain formed by the pipe roof acts as the main load, freezing up the water sealing function and preventing the water and soil loss between the pipes. This paper is based on the Zhuhai connection line project of the Hong Kong Zhuhai Macao Bridge, which is being built, and combines with the practice of the Gongbei port excavation section, and adopts the indoor model. The variation law of section angle and pipe joint stress of single pipe jacking pipe was tested and studied, and the interaction between pipe roof pipe group was studied by indoor model test and numerical analysis. It provided reference for the formation of curve pipe curtain. The freezing effect of frozen water stop curtain in active freezing period and freezing period was studied, and the effect on frost heave deformation was also studied. The numerical simulation analysis is carried out to obtain the following main achievements: 1, the pipe curtain freezing method is technically feasible, and can provide a new idea for the excavation under complex conditions,.2. When the jacking force is calculated according to the empirical formula, the influence of various factors on the jacking force should be fully considered. The transfer of the jacking force during the curve jacking process With the asymmetry distribution, the pipe joint strain decreases along the axis basically, and the pipe joint will have a certain deflection.3. Through the study of the interaction between adjacent pipe jacking, it is shown that the rear top pipe will have a certain effect on the pre fixed pipe jacking. The top pipe of the pipe jacking is followed by the top of the top pipe in the middle of the top two tubes. In the two top pipe, there is a large yield of soil, and the rear top pipe will produce a certain additional force on the top top pipe. By controlling the jacking parameters of the pipe jacking construction and measuring the deviation in time, the interaction between the pipe roof pipe can be effectively reduced, and the pipe curtain can be formed to form.4. In the active freezing period, only the circular freezing pipe is opened. The water sealing effect of pipe jacking pipe can be realized, but it takes a long time to form the designed frozen soil thickness. The frozen tube can be obviously improved by the special shape strengthening freezing pipe. Therefore, in the engineering application, it is suggested that the circular freezing tube and the special shape strengthen the freezing pipe be synchronized with the freezing pipe during the active freezing period. Scheme.5, in the maintenance of freezing period, in order to reduce the effect of freezing effect and help to excavate the construction work of the excavation section, the air temperature in the excavation section should be controlled at 25 degrees C. The wind speed of the excavation section has no significant influence on the freezing effect. The ventilation of the excavation section needs no strict.6, and the opening of the limit tube has a very significant influence on the freezing effect. The opening of the pipe can effectively control the thickness of frozen soil. The temperature of the fluid in the limit pipe has a great influence on the freezing effect. It is to avoid the penetration phenomenon and effectively limit the thickness of the frozen soil. The temperature of the fluid in the limit tube should be about 15.7, the maximum uplift of the surface, the maximum horizontal displacement, the impact range of the uplift and the horizontal displacement with the thickness of the frozen soil wall. The displacement of the upper end of the pipe curtain and the lateral end pipe increase linearly with the increase of the thickness of the frozen soil wall. Therefore, it is necessary to control the thickness of the permafrost wall in the engineering so as not to have a greater influence on the surrounding environment,.8, the maximum location of the maximum ground point of the ground and the horizontal displacement of the earth's surface almost does not vary with the thickness of the frozen soil wall. Change, the maximum long starting point always occurs at the position of the surface vertical corresponding to the center of the dark excavation section, the maximum horizontal displacement always occurs near the position of the corresponding ground at the lateral 5m of the lateral wall of the pipe curtain.

【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU94

【参考文献】