【作者】 杨仙；

【导师】 张可能；

【作者基本信息】 中南大学 ， 地质工程， 2012， 博士

【摘要】 沈阳地铁新乐遗址站为暗挖车站,采用管幕预筑法施工。管幕预筑法是在传统的管幕法基础上改进形成的。管幕预筑法所使用的钢管直径大,可以达到2米以上。在顶进的钢管保护下人工或机械进入钢管内部开挖排土。然后对钢管进行切割并支撑,在钢管内进行结构浇筑。最后等结构强度及刚度达到要求后,再进行结构下大范围土体开挖,形成大断面的地下空间。该工法最突出的特点是：整个过程中,所有的开挖都是在预先建造了可靠结构后完成的,因此保证了施工安全。由此可见,顶管是该工法中至关重要的一个环节,其为后续工序预先制造了安全的工作空间,从而减小了施工风险。然而,该工法中顶管工程与普通的顶管工程相比较,有很大的特殊性。主要体现在顶管埋深大、管径大、数量多、管间距小、排列形式复杂。本文以沈阳地铁新乐遗址站工程为依托,总结了该工法中的顶管施工技术,着重研究了密集大口径钢管群顶进与土体之间的相互作用,以及顶管过程造成的环境影响等。密集大口径钢管群顶进与土体之间的相互作用方面,主要研究了如下内容：(1)结合文献分析与本工程顶管顶力实测数据,分析了现有垂直土压力计算理论的不足。基于普氏理论和太沙基理论提出了改进垂直土压力计算理论,并编制了Matlab计算程序用于深埋顶管顶力计算。计算结果表明改进垂直土压力理论计算结果小于普氏理论和太沙基理论计算结果,与实测结果更接近。(2)结合实测结果,对顶管过程中管道的轴线偏移和管头变形进行了理论分析。提出通过顶管应力监测来进行管道轴线的实时偏移判断,并通过顶管应力监测试验验证该方案是可行的。(3)利用弹性力学和土力学相关知识,对顶管过程中的开挖面稳定性进行了理论分析。(4)利用土拱效应的理论知识,提出了顶管间距的优化设计方法。并结合本工程实际情况,对顶管间距进行优化设计,得到了2种优化方案。相对于原方案,优化方案能节省钢材,缩短顶进施工的时间,并可以减小顶管造成的土体重复扰动。密集大口径钢管群顶进环境影响研究主要包括以下内容：(1)分析了密集大口径钢管群顶进对地面沉降的影响。通过实测和理论计算,提出密集大口径钢管群顶进地表沉降主要是由顶管土体损失和地下水渗流引起的。已建顶管的支挡作用会限制土体向下位移,大大减小新建顶管造成的地表沉降,因此由顶管土体损失引起的地表沉降一般较小,不会超过沉降警戒值。而地下水渗流引起的地表沉降远大于顶管土体损失引起的地表沉降,地下水渗流严重时,地表沉降会远大于沉降警戒值。(2)根据刚性管道与顶管间距大小,把顶管对刚性管道的影响分为远距离影响和近距离影响两种类型。并且基于Winkler弹性地基梁理论,提出了两种情况下顶管作用使既有刚性管道产生的位移、转角、弯矩以及剪力的计算方法。编制了Matlab计算程序对刚性管道产生的位移、转角、弯矩以及剪力进行计算,结合管道失效标准,能方便地判断其是否稳定。(3)在该工法中,注浆主要有3个目的：顶管减阻,注浆抬升以及注浆加固。本文对顶管工程注浆进行了研究,并分析了各种注浆方法在本工程中取得的效果。本文的部分研究成果已在沈阳地铁新乐遗址站得到了应用。更多还原

【Abstract】 Xinle Ruins Station of Shenyang Metro is a Mining Station, which is constructed by Pipe-roof Pre-construction Method. Pipe-roof Pre-construction Method is an improvement on the basis of the formation Pipe-roofing Method. The steel pipe diameter can reach more than2meters in Pipe-roof Pre-construction Method. The soil is excavated inside the steel pipe manually or mechanically under the protection of jacking pipe. Then the steel pipe is cut, support structure is welded, and reinforced concrete structure is poured in the pipe. After strength and rigidity of reinforced concrete structure is attained, the soil under reinforced concrete structure is excavated and large cross section of underground space form. The most prominent feature of the construction method:through out the process, all of the excavation is completed after the pre-built and reliable structure, thus ensuring construction safety.Thus, the pipe jacking is a vital link in the construction method, which pre-manufactured a safe working space for follow-up process, thereby reducing the risk of construction. However, compared with the ordinary pipe jacking project, jacking pipe in this construction is with great particularity. Mainly reflected in the deep depth, full diameter, large quantity, and arranged in the form of complex. Based on Xinle Ruins Station of Shenyang Metro, the pipe jacking technology in the construction method is summed up, the interaction between the intensive full diameter steel pipe group and soil is focused on, as well as the environmental impact caused by the pipe jacking process and so on.The interactions between the intensive full diameter steel pipe group and the soil are of the following:(1) Combined with literature review and measured data of jacking force, the theoretical deficiencies of existing vertical earth pressure calculation is analyzed. New theoretical formula is got based on Terzaghi theory and M.M.PROMOJIYFAKONOV theory, and Matlab calculation program is written for jacking force calculation of the deep buried pipe. The calculation results show that the calculation results by the improved vertical soil pressure theoretical is less than that by Terzaghi theory and M.M.PROMOJIYFAKONOV theory, which is closer with measured results.(2) Combined with measured results, theoretical analysis of pipe axis offset and head deformation in jacking is proposed. It is proposed to carry out real-time monitoring of pipe axis by the pipe jacking stress monitoring, and proves the program is feasible by testing.(3) Based on knowledge of elastic mechanics and soil mechanics, theoretical analysis on the stability of the excavation surface is made in jacking.(4) Based on soil arching effect, optimum design method of the distance between pipes is put forward. Combined with this project, optimum distance is designed, and two kinds of optimization are got. Relative to the original program, the optimization program can save steel, shortening the time of the construction of the jacking, and can reduce repeated disturbance of soil in jacking.The environmental impacts caused by the pipe jacking process are of the following:(1) The surface settlement is caused by the dense jacking of full diameter pipes group. By the measured and theoretical study, it indicates that surface settlement is mainly caused by the loss of soil in jacking and groundwater seepage. Supporting and retaining of existing pipe will limit the downward displacement of soil, and greatly reduce the surface settlement caused by new pipe, so the surface settlement caused by the loss of soil in jacking is generally small, and no more than the value of the settlement alert. Surface settlement caused by groundwater seepage is much larger than that caused by the loss of soil. So serious groundwater seepage can cause much larger surface subsidence than the alert value.(2) According to the distance between rigid pipe and the jacking pipe, the impact is divided into two types:far-impact and close-impact. Based on the Winkler elastic foundation beam theory, the calculation method of the displacement, rotation, bending moment and shear of existing rigid pipe by jacking is proposed. And Matlab calculation program is written for the calculation of displacement, rotation, bending moment and shear. Combined with pipeline failure criteria, the stability can be determined easily.(3)In the construction method, grouting has three purposes:friction reduction in jacking, uplifting of surface, and reinforcement. Grouting in pipe jacking is researched, and effect of all kinds of grouting is analyzed.Parts of the research results in this paper have been used in Xinle Ruins Station of Shenyang Metro.更多还原