长深高速公路承德段长逢沟隧道初期支护湿喷混凝土施工关键技术研究

发布时间：2018-06-21 09:08

本文选题：湿喷混凝土 + 公路隧道　；参考：《长安大学》2014年硕士论文

【摘要】：我国在公路隧道施工中广泛的采用了新奥法（New Austria Tunneling Method，简写NATM），新奥法以喷射混凝土、锚杆加固和量测技术为三大支柱。长期以来，公路隧道施工中普遍采用干喷混凝土施工工艺，但是干喷混凝土由于施工工艺和施工设备等原因，混凝土配合比中的水由操作工人喷嘴处无计量方式的直接加入，粉态速凝剂也由操作工人无计量方式的添加，导致根本无法控制混凝土的水灰比和外加剂的实际参量，故强度根本无法保障；给公路隧道的初期支护质量和施工过程及运营阶段的安全造成了较为严重的影响。本文以长春至深圳高速公路承德至朝阳段长逢沟隧道初期支护湿喷混凝土施工实例为依托，对湿喷混凝土的配合比设计与优化、抗压强度参数、湿喷混凝土施工工艺及质量管理进行了研究。内容包括如下几个方面：（1）根据《普通混凝土配合比设计规程》JGJ55-2000规定进行C25湿喷混凝土基准配合比设计（基准配合比为：mCo：mSo：mGo：mWo=430:899:766:205）；通过满足施工工作性的需要，按照“不堵管、回弹少、附着性好”为原则进行现场实际湿喷试验，对用水量、砂率、水泥用量等参数进行了调整和优化，得出优化配合比为mCo：mSo：mGo： mWo=424:902:769:205。（2）通过施工现场采用湿喷工艺制作喷射混凝土大板试件，并按照相关喷射混凝土试验检测规程进行抗压强度的测试。为了进行湿喷工艺与干喷工艺的混凝土强度对比分析，在上述湿喷施工现场，同时采用干喷工艺制作喷射混凝土大板试件，配合比参照湿喷配合比（除水用量）进行混合干料拌合并运输至施工现场，按照相关试验检测规程进行混凝土强度的测试。通过对湿喷、干喷两种施工工艺下，各50组试件的混凝土强度测试及数据分析可以得出，采用湿喷工艺施工的混凝土密实、饱满，湿喷混凝土平均强度（30.44MPa）比干喷混凝土的平均强度（22.86MPa）高出7.58MPa，湿喷混凝土的标准方差、变异系数、平均极差及平均移动极等指标参数差明显低于干喷混凝土，湿喷混凝土的强度指标质量稳定性明显优于干喷混凝土。（3）通过长逢沟隧道喷射混凝土回弹率现场测定，得出边墙平均回弹率9.1%，拱顶平均回弹率18.8%，，与相关文献资料显示的干喷混凝土回弹率边墙部位为20～30%，拱顶部位为40～50％对比可以得出，湿喷混凝土的回弹率明显低于干喷混凝土。（4）喷射混凝土回弹率、密实度的影响因素主要有隧道围岩状态、混凝土配合比、施工方法（压送压力、喷射距离、喷射角度、喷射位置、喷射作业操作工人技术水平等）。喷射过程中，应根据出料情况调整风量，风压控制在0.3~0.6MPa之间；严格控制喷枪与喷射面的距离和喷枪与喷射面的夹角，喷枪与喷射面的距离为1.0～1.5m，喷枪与喷射面基本保持垂直并连续平稳地按小圆周形或椭圆形螺旋状旋转喷射，可以有效的降低回弹量，提高密实度。（5）湿喷混凝土质量控制中严格控制原材料质量、加强施工作业管理、强化养护管理等是关键因素，针对强度、厚度、空洞、平整度、渗水等质量通病应该采取有效措施办法进行控制。
[Abstract]:In our country, are extensively used in highway tunnel construction of NATM (New Austria Tunneling Method, abbreviated NATM), the new Austrian method to shotcrete, anchor reinforcement and measurement technology for the three pillars. For a long time, the dry spraying concrete construction technology is widely used in highway tunnel construction, but the dry sprayed concrete due to the construction process and construction equipment Other reasons, concrete mix ratio in the water by directly adding workers without metering nozzle, add powder accelerator by workers without metering mode, resulting in the actual parameter cannot control the water cement ratio of concrete and admixture, the strength can not guarantee; for highway tunnel initial support quality and construction More serious impact caused by the process and operation stage. In this paper, the safety of wet shotcrete construction example Changchun Shenzhen Expressway to Chengde Chaoyang section of Changfeng tunnel initial support based on the mix design and optimization of wet sprayed concrete, compressive strength, wet shotcrete construction technology and quality management are studied. The contents are as follows:
(1) according to the provisions of design code for >JGJ55-2000 C25 than the wet sprayed concrete mix proportion design of ordinary concrete base (base mix ratio: mCo:mSo:mGo:mWo=430:899:766:205); by meeting the needs of the construction work, in accordance with the "no plugging, less resilience, good adhesion for the principle of actual wet spray test for Water, sand ratio, dosage of cement and other parameters are adjusted and optimized, the optimum mix ratio is mCo:mSo:mGo:mWo=424:902:769:205.
(2) the construction site by the wet spray process of spray concrete slab specimens, and in accordance with the relevant rules of concrete injection detection test compressive strength test. In order to carry out the wet spray process and concrete strength comparison of dry shotcrete analysis in the wet shotcrete construction site, and the production of dry shotcrete shotcrete slabs Specimen mix reference wet spray mix (except water) mixed with dry mix transportation to the construction site, the concrete strength test in accordance with the detection test standard. Based on the dry jet wet spray, two kinds of construction technology, concrete strength test and data analysis of the 50 groups of specimens can be obtained. The construction technology of wet spraying Concrete is dense, full, wet sprayed concrete average strength (30.44MPa) than the average strength of sprayed concrete (22.86MPa) is higher than 7.58MPa, standard deviation, coefficient of variation of wet shotcrete, average range and average moving pole parameters difference was significantly lower than that of dry sprayed concrete, the strength index of the quality stability of wet shotcrete is better than dry Sprayed concrete.
(3) through the long tunnel on injection rate was detected on the concrete rebound, the side wall of the average rebound rate was 9.1%, the average crown rebound rate 18.8%, and the related literature shows that dry shotcrete rebound rate of side wall is 20 ~ 30%, 40 ~ 50% vault comparison can be obtained, the rebound rate of shotcrete dry spray was significantly lower than that of concrete.
(4) the shotcrete rebound rate, factors affecting the density of the main tunnel surrounding rock, concrete mix ratio, construction method (pressurization pressure, jet distance, jet angle, jet position, injection technology level of operation workers). In the injection process, should be based on the material conditions to adjust the air volume, air pressure control in 0.3~0.6MPa between strict control; For spray and spray distance and the angle between the surface and spray gun, spray gun and the distance is 1 ~ 1.5m, spray gun and spray surface remained vertical and continuously and smoothly by small circular or oval shaped spiral jet, can effectively reduce the springback, improve the compactness.
(5) wet sprayed concrete quality control and strictly control the quality of raw materials, strengthen construction management, strengthen the maintenance and management are the key factors for the strength, thickness, hole, flatness, water quality defects should take effective measures to control.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.48;U459.2

【参考文献】