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首页> 外文会议>North American Tunneling 2000, Jun 6-11, 2000, Boston, Massachusetts >Instrumentation controls for chemical grouting during tunneling operations. Boston, Massachusetts
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Instrumentation controls for chemical grouting during tunneling operations. Boston, Massachusetts

机译：隧道作业期间化学灌浆的仪表控制。马萨诸塞州波士顿

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The Central Artery Tunnel Project located in Boston Massachusetts is the largest and most complex highway project in American history. One of the Projects main elements is the replacement of the elevated Interstate 93 through downtown Boston with an underground highway. At its deepest point the underground highway is 120 feet (36 meters) below grade and passes directly beneath an existing subway tunnel/station. To tunnel beneath the existing subway a significant underpinning structure was required consisting of stacked drift tunnels and post tensioned roof girders or cross adits. To facilitate mining two shafts were dropped approximately 120 feet (36 meters), the water table was temporarily lowered and two access tunnels/grouting galleries were mined in a cohesive granular till. The underlying stacked tunnel drives were driven in pervious gravel deposits overlaying Argillite bedrock. The stacked tunnel drives and cross adits were mined open face with a combination of ribs and liner plates. Permanent dewatering could not be performed due to settlement concerns, since, the nearby adjacent high rises bear on mat foundations and the nearby historical structures are supported on timber pile foundations bearing in clay. To facilitate the open face mining, of the lower drifts in the pervious gravel soils, ground stabilization was required. Prior to the ground modification being performed, an instrumentation system was installed and initialized in the active transit tunnel located approximately 1 meter (3 feet) above the crown of the access tunnels. The instrumentation system included 3 separate "strings" of vibrating wire liquid level displacement transducers. The strings, each approximately 50 meters (150 feet) long, were installed along the inbound and outbound track platforms and along the cen-terline columns between the tracks. All of the strings were connected to an Automated Data Acquisition System (ADAS) which was monitored remotely via modem. Ground modification was performed by injecting sodium silicate grout through tube-a-manchette or TAM pipes creating a mass of chemically stabilized soil under each access tunnel. During the early grouting program vertical upward deformations were measured by the liquid level system and confirmed by optical survey. Multiple modifications were made in an attempt to limit the heave while still creating the required grout curtains. Such modifications included: additional pressure relief via dewatering wells, reductions in injection pressures, reductions in flow rates, reductions in the grout viscosity, revisions to the grouting sequence, reductions in the number of active packers, a replacement of sodium silicate with acrylate grout. All of the contract modifications were performed under a heave based limiting criteria. In summary, the monitoring system provided a degree of confidence during the grouting operations allowing the maximum amount of grout to be injected while maintaining heave within acceptable limits to the Owner. Over 950,000 liters (250,000 gallons) of grout were injected and the drifts and cross adits have been successfully mined without incident.
机译：位于马萨诸塞州波士顿的中央动脉隧道项目是美国历史上规模最大，最复杂的高速公路项目。该项目的主要内容之一是用地下高速公路取代穿过波士顿市中心的高架93号州际公路。地下公路在最深处低于坡度120英尺（36米），并直接通过现有地铁隧道/车站的下方。为了在现有的地铁下面开挖隧道，需要一个重要的支撑结构，包括堆叠式漂移隧道和后张拉的屋顶大梁或十字路口。为了便于开采，将两个竖井掉落到大约120英尺（36米）处，暂时降低了地下水位，并在一个粘性的粒状矿坑中开采了两个通道/灌浆通道。下方的堆叠隧道驱动器由覆盖在Argillite基岩上的透水砾石沉积物驱动。堆叠的隧道掘进机和交叉平巷采用肋骨和衬板的组合进行露天开采。由于沉降问题，无法进行永久性的脱水，因为附近的高耸建筑物临近垫层基础，附近的历史建筑物支撑在承重于粘土的木桩基础上。为了便于露天开采，在透水砾石土壤中较低的漂移处，需要地面稳定。在进行地面修改之前，在活动通道中安装了仪表系统并进行了初始化，该通道位于通道顶部附近约1米（3英尺）处。仪器系统包括3个单独的“弦”，它们是振动线液位位移传感器。每条线长约50米（150英尺），沿着入站和出站轨道平台以及沿轨道之间的中线列安装。所有的字符串都连接到通过调制解调器远程监视的自动数据采集系统（ADAS）。地面改性是通过在手动通道或TAM管道中注入硅酸钠灌浆来进行的，从而在每个通道下方形成大量化学稳定的土壤。在早期注浆程序中，通过液位系统测量垂直向上的变形，并通过光学测量进行确认。进行了多次修改，以试图限制升沉，同时仍然创建所需的灌浆帘。此类修改包括：通过脱水井额外释放压力，降低注入压力，降低流速，降低灌浆粘度，修改灌浆顺序，减少有效封隔器数量，用丙烯酸酯灌浆代替硅酸钠。所有合同修改都是在基于波动的限制标准下进行的。总而言之，监控系统在灌浆操作过程中提供了一定程度的可信度，可以注入最大量的灌浆，同时保持船东的起伏在可接受的范围内。注入了超过950,000升（250,000加仑）的水泥浆，并且成功地开采了漂流物和交叉ad石，没有发生事故。

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