针对隧道工程中新建隧道小角度斜下穿既有隧道工程中亟待解决的难题，以西安地铁1号线二期张家村-后卫寨区间左线盾构下穿既有1号线出入段线为工程依托，通过现场调研、数值模拟和现场监测等方法进行施工参数对轨道既有隧道和轨道高差的沉降规律（重点进行对轨道高差的控制）研究。选取土仓压力、注浆压力、注浆量等施工参数，其中注浆量用注浆厚度间接体现，构建三维数值计算模型，并对结果进行分析，依据分析结果给出合理的盾构施工参数建议值，在此基础上进行现场监测，验证给出的施工参数建议值对轨道高差的控制效果。研究结果表明：随着土仓压力、注浆压力的增大，既有隧道的沉降和轨道高差不断减小，当其土仓压力超过0.10 MPa、注浆压力超过0.22 MPa时，既有隧道沉降和轨道高差控制效果不再明显提高；既有隧道沉降和轨道高差随着注浆厚度的增大而减小，其与注浆厚度均近似呈线性关系，因此适当增大注浆范围是控制既有隧道沉降和轨道高差的有效方法；确定的施工参数建议值为0.10 MPa（土仓压力）+0.22 MPa（注浆压力）+0.23 m（注浆厚度）；通过现场监测，既有地铁隧道道床上C，B，G，F四条测线上最大沉降量均在6 mm左右（小于20 mm），最大轨道高差为1.2 mm（小于4 mm），均小于规范所要求的控制值，表明以上施工参数建议值对于既有隧道沉降和轨道高差起到了很好控制效果。

New tunnels that closely undercross existing tunnels at small angles cause problems that need to be solved. The left line of the shield tunnel section that starts from Zhangjiacun station to Houweizhai station in the Xi'an Metro Line 1 is constructed in close proximity to the existing Line 1 above it. Thus, field investigations, numerical simulation, and field monitoring were used to analyze the influence of construction parameters on the settlement and distance between two tracks of the existing tunnels. This study chose the construction parameters to be soil pressure, grouting pressure, and grouting amount, and the grouting amount was indirectly measured through grouting thickness. A three-dimensional numerical simulation model was constructed. By analyzing the results of the simulation, reasonable values of shield construction parameters were obtained. Field monitoring was carried out to verify the control effect of the proposed construction parameters on the track height difference. The results show that with the increase of chamber pressure and grouting pressure, both the settlement of existing metro tunnels and the distance between two tracks will continue to decrease; however, when the chamber pressure increases to 0.10 MPa and grouting pressure increases to 0.22 MPa, the control effects are no longer significantly improved. Therefore, the settlement of existing lines and the distance between two tracks decrease with the increase of the grouting thickness, which shows an approximately linear relationship. Thus, increasing the grouting range is an effective method to control the settlement and orbital difference of existing tunnels. From the numerical simulations, the recommended values of the construction parameters are 0.10 MPa for chamber pressure, +0.22 MPa for grouting pressure, and +0.23 m for grouting thickness. Through field monitoring, on the existing subway tunnel bed, the maximum settlement of the four measured lines C, B, G, and F are found to be approximately 6 mm, less than 20 mm, and the maximum rail height difference is 1.2 mm, less than 4 mm. These are all seen to be less than the control values required by the specifications, indicating that the suggested construction parameters have a good control effect on the existing tunnel settlement and rail height difference.

大型引调水工程建设在穿越或临近城区时经常面临浅埋隧洞施工影响控制难题。针对城区浅埋隧洞近接施工,提出一种包括施工条件分析、施工方法比选、设计方案确定、施工过程反馈和动态设计优化等环节的全过程动态闭环反馈控制方法。其中,施工条件分析应统筹考虑工程地质条件和建(构)筑物交叉关系等影响因素,施工方法应通过技术经济综合比较确定,变形预测和变形控制标准是设计方案的重要组成部分,施工过程多源信息反馈和动态设计优化是近接施工影响控制的关键。滇中引水工程输水总干渠过昆明城区浅埋段下穿或邻近侧穿各类敏感建(构)筑物100余座,施工环境极其复杂,采用全过程动态闭环馈控方法,可保证近接施工影响整体受控。

Controlling the influence of shallow-buried tunnel construction has always been a challenge for large-scale water diversion project while passing through or near urban area. A dynamic closed-loop feedback-control method for the whole construction process is proposed. The method includes analysing construction conditions, comparing and selecting construction method, determining design scheme, construction process feedback, and dynamic design optimization. In analysing construction conditions, engineering geological condition and cross relations of buildings as well as other necessary influencing factors should be considered as a whole. Construction method should be determined comprehensively by technical and economic comparison. Deformation prediction and deformation control standard are crucial parts of design scheme. Multi-source information feedback and dynamic design optimization are keys to the influence control of adjacent construction. Passing through over 100 sensitive buildings and other structures, the shallow-buried segment of Central Yunnan Water Diversion Project crossing the urban area of Kunming is featured with extremely complex construction environment. The influence of its construction adjacent to the urban area can be under control in general by using the proposed dynamic closed-loop feedback-control method.

为探明新建隧道施工的扰动影响范围以提出施工对策,从而保障既有隧道的安全运营,依托北京地铁新机场线上跨既有地铁10号线工程,采用FLAC^3D有限差分软件对不同埋深、净距下的既有隧道进行了施工仿真计算分析。基于既有隧道拱顶位移控制标准,即控制值2 mm和预警值1.4 mm,将扰动影响分域划分为强影响区、弱影响区和无影响区。根据施工影响分区及工程特点,提出了超前管幕和超前管幕+夹土注浆2种加固措施,并进行数值模拟分析。结果表明:超前管幕加固措施位移减小64.05%;超前管幕+夹土注浆加固措施位移减小70.23%。结合现场控制标准,近接施工采取超前管幕+夹土注浆加固措施能够保障新建隧道的施工安全性及既有隧道的运营安全。