超深防渗墙混凝土浇筑控制及滑管脱模关键技术研究

发布时间：2018-04-15 20:51

本文选题：超深防渗墙 + 接头管法　；参考：《天津大学》2014年博士论文

【摘要】：作为土石坝基础工程中最重要的防渗设施之一，防渗墙对于保证大坝安全、减少库区渗漏具有重要作用。近年来，随着水利水电工程建设的不断发展，水电开发逐渐向西部山区和高海拔地区推进，水利建设的迅速发展对超深覆盖层地区的混凝土防渗墙技术提出了更高要求。各单元墙段由接缝连接成防渗墙整体，墙段间的接缝是防渗墙的薄弱环节。在所有的墙段连接型式中，接头管法由于接缝质量好，且可避免混凝土浪费，加快施工进度而在超深防渗墙施工中深受青睐。理论分析和工程实践表明，对于接头管法的超深防渗墙施工而言，确定接头管的拔管时机和拔管起拔力以及混凝土浇筑速度控制过程中的参数是制约施工质量和施工进度的两个关键问题。确定拔管时机主要包含两个层面的意义：一是在浇筑混凝土后较早拔管，以避免由于混凝土凝固导致起拔困难，甚至引起铸管；二是在浇筑混凝土后较晚拔管，以有充足的时间使混凝土稳固，而不致由于外部荷载导致拔管后混凝土坍塌，实际上是相互矛盾而又紧密联系的两个方面；而拔管时机和孔斜对拔管力的大小具有重要影响。论文以数值模拟为主要理论分析手段，以西藏旁多水利枢纽150m超深防渗墙施工为研究对象，对超深防渗墙混凝土浇筑进行了温度～结构场耦合分析，深入研究了超深防渗墙的拔管时机，对不同拔管时机、不同孔斜下的拔管力进行了分析，并以现场试验进行了验证；采用离散元法研究了混凝土浇筑过程中的施工控制参数，结果表明：（1）接头管的拔管时机受控于混凝土的稳固机制，受诸多因素影响，包括环境条件、荷载条件和施工条件等，具体到旁多项目150m的超深防渗墙而言，数值分析表明：在保持混凝土浇筑面距接头管底端40m的情况下进行拔管是满足要求的；（2）拔管力的大小主要与拔管时机和孔斜相关。不同的拔管时机导致接头管与混凝土之间不同的接触特性，进而影响拔管力；孔斜会增大拔管力，且随着孔斜增加，拔管力增加迅速。在初浇混凝土40m拔管且无孔斜情况下，拔管力大小约为500t；（3）接头管法施工混凝土浇筑参数控制主要包括浇筑导管口距槽孔底部最佳距离、导管在混凝土中的埋深、不同浇筑深度下浇筑混凝土下降速度等。数值分析表明：①混凝土初浇时，浇筑导管距槽底距离应控制在3～4倍导管直径范围；②浇筑结束阶段，浇筑导管内外混凝土高差应控制在5m以内；③随防渗墙深度的增加，混凝土在导管内下降形态呈较明显的间断现象，但在150m的深度范围内无明显离析和粗细骨料分离现象；（4）现场实践表明，拔管时机以初浇混凝土后7～8小时为宜，即浇筑混凝土40m左右开始拔管；拔管力大小受诸多因素影响，主要与接头管与混凝土之间的接触特性和孔斜相关。现场实践与理论分析成果具有较好一致性。论文给出了超深防渗墙接头管法施工中拔管时机和拔管力的分析方法，同时，对混凝土浇筑过程中控制参数的选取进行了初步探讨，对于提高超深防渗墙施工质量和加快施工进度具有一定的参考价值。
[Abstract]:As one of the most important foundation of earth rockfill dam anti-seepage facilities, anti-seepage wall to ensure dam safety, which plays an important role in reducing the reservoir leakage. In recent years, with the continuous development of hydropower projects, hydropower development gradually advancing to the western mountains and high altitude, the rapid development of water conservancy construction of ultra deep covered concrete cutoff wall the region has put forward higher requirements.
Each cell wall section connected into impervious wall by the seam, the seam between the wall section is the weak link of impervious wall in wall section. All the connection type, joint tube method due to the joint quality is good, and can avoid the waste concrete, accelerate the construction progress in super deep diaphragm wall construction in theoretical analysis show that favored. And the engineering practice, for the joint tube method for super deep diaphragm wall construction, determine the extubation joint pipe pulling force and concrete pouring speed control process parameters are two key problems restricting the construction quality and the construction progress of the time and extubation. Determine the extubation time mainly includes two levels: one is after the pouring of concrete early extubation, in order to avoid the concrete solidification lead pulling difficult, even cause the pipes; two is in pouring concrete after late extubation, to have sufficient time to make the concrete solid, and not by The external load results in the collapse of concrete after extubation, which is actually contradictory and closely related to two aspects. The timing and the inclination of the pipe have an important influence on the size of the extubation force.
Based on the numerical simulation as the main means of theoretical analysis, taking Tibet Pangduo hydro 150m super deep diaphragm wall construction as the research object, the ultra deep cut-off wall concrete analyzed temperature field coupling to the structure, in-depth study of the super deep diaphragm wall on different extubation time, extubation time, different oblique hole the pulling force is analyzed, and based on the field test; study the construction parameters of the concrete pouring by discrete element method. The results show that:
(1) stable mechanism of tube extubation time is controlled by the concrete joints, affected by many factors, including environmental conditions, loading conditions and construction conditions, specific to the super deep diaphragm wall beside the 150m project, the numerical analysis shows that: in keeping concrete surfaces from the bottom joint pipe under the condition of 40m extubation is to meet the requirements of;
(2) the pulling force and extubation time and the size of the main hole. Different extubation time lead to different contact characteristics between the joint pipe and concrete, and then affect the pulling force; oblique hole will increase the pulling force, and with the increase of Kong Xie, the pulling force increases rapidly in the beginning of concrete 40m. Extubation and no hole case, the pulling force is about 500t;
(3) joint control parameters of concrete pouring construction method mainly includes pouring pipe mouth from the bottom slot optimal distance, catheter in concrete depth, different depth of concrete pouring down speed. Numerical analysis shows: the concrete initial pouring, pouring pipe from the tank bottom should be controlled at a distance of 3~4 times the diameter of the tube range the end of the stage; pouring, pouring pipe inside and outside the concrete height should be controlled within 5m; with the increase of the depth of the concrete cutoff wall, decreased in the duct shape is discontinuous phenomenon obviously, but in the depth range of 150m no obvious segregation and coarse aggregate segregation;
(4) the field practice shows the extubation time in 7~8 hours after the beginning of concrete pouring of concrete that is appropriate, started around 40m extubation; pulling force size is influenced by many factors, the main pipe and the contact characteristics between concrete and oblique holes associated with joint. The field practice and theoretical analysis results have good consistency.
This paper gives a super deep diaphragm wall pipe construction method in extubation method, tube time and pull at the same time, the selection of control parameters of concrete pouring process are discussed, which has a certain reference value for improving the construction quality of super deep diaphragm wall and accelerate the construction progress.

【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV543.8

【参考文献】