Rotational Moment Analysis and Posture Rectification Strategy of Shield Machine-外文翻译.doc

外文翻译 第19页 1 英文Rotational Moment Analysis and PostureRectification Strategy of Shield MachineAbstract. The rolling phenomenon of the shield body occurs frequently in the process of practice construction, which could lead to the derivation of the shield machine and increase the difficulties of the excavation control. It is mainly caused by the rotation of the cutter head. Based on this practical problem, we investigate the forces around the shield body and the cutter head. Meanwhile, the positive and negative rotary controlling techniques are developed to regulate the deviated rolling angle. These studies would provide theoretical basis to the further research about the whole postures rectification of the shield machine.Keywords: Shield machine, Rotation moment analysis, Rectification strategy.1 Introduction1.1 Shield Tunneling Method Shield machine is an important technique equipment in basic construction and resource development, which is widely applied in tunnel, railroad, highway, mineral mountain etc underground construction. The shield tunneling method is a method to construct tunnel with shield machine. During shield excavation, the jack at the shield tail push the tunnel segment which had been assembled where a reaction force occurred to make the shield going forward, at the same time the excavation plane must keep stabile. Comparing with cut and cover method, shield tunneling method have some merits as follows:1, Less occupied ground surface, less land expropriation cost.2, The influence of weather condition is small, so there will be longer effectiveconstruction time comparatively.3, Soft soil, sand egg soil, soft rock and the rock strata are all applicable.4, The construction speed is quick.5, The influence to the environment is small.According to the above merits, the shield tunneling method get extensive application.1.2 Rotation Posture Rectification Position and posture of shield machine is important to precision of tunnel construction during excavation. But there must have deviation from actual position and posture to desired position and posture. So the rectification of the deviation is necessary. In this paper, we do not discuss position rectification. In posture rectification, only rotation rectification is considered. Posture of shield machine is described by three parameters: the pitching angle p ,the yawing angle y and the rotation angle r. The pitching anglep is the angle between shield machine axis and horizontal plane. The yawing angle is the angle between shield machine and vertical plane through the shield machine axis. The rotation angle is the angle that the shield machine rotates on the shield machine axis. In the following description, replace p with . To illustrate, the following coordinate system is established.Fig. 1. Coordinate systems are established The global coordinate system CE is selected so that the z axis is vertically downwards and the x and y axes are on a horizontal plane. The x, y and z axes are perpendicular to each other and follow the right-hand rule. A machine coordinate system CM is selected so that the p axis is vertically downward when the shield being not rotate and the r axis is in the direction of the machine axis. The CM consolidate with the shield. The origin of the machine coordinate system is selected at the center of the shield tail plane. The p , q and r axes are perpendicular to each other and follow the right-hand rule. A reference coordinate system CMV is selected so that the pv axis is through the cross-line of PV and shield tail plane and the rv axis is in the direction of the machine axis. The pv and qv axes are on the shield tail plane. The pv is the vertical plane through shield axis. The origin of the reference coordinate system is selected at the center of the shield tail plane. The pv , qv and rv axes are perpendicular to each other and follow the right-hand rule. The angle between p axis and pv axis is the rotation angle . The is positive for counterclockwise rotation of shield (view from shield tail). Shield rotation posture rectification means zero when is not zero. During excavation, if is not zero, the actual jack thrust distribution will be different from theoretical jack thrust distribution. That will lead to algorithm deviation. More serious condition is that is over certain threshold which will lead to propulsion failure and segment assembly failure.1.3 Previous Research In literature 1, the silt sandy ground in Shanghai area is taken as prototype, then different parameters of shield machine and ground properties be combined for testing. Based on the test results, studies are carried out to discover the variation law of thrust force, the mechanism of friction between soil and shield and its influence factors. In literature 2, soil cutting force was investigated and a soil cutting force model was proposed. In literature 3,4,5, the reasonable calculation method of thrust force and its influencing factors were studied by applying mathematics and mechanics based on the working mechanism of EPB shield machine. In order to research on shield rotation rectification, a shield rotation moment model must be established. The previous research is helpful to establish the model, but no specialized research was carried on.2 Rotation Rectification Strategy The rotation rectification strategy includes four steps: rotation angle measurement, cause analysis, need to rotation rectification or not, rotation rectification. Rotation angle measurement can be measured by an inclinometer in the shield. Based on the shield rotation moment model, the reasons that cause the current rotation situation could be found out. If 1.5 , rotation rectification by counter rotation of cutter is needed. When p and y rectification is proceeding, rotation rectification is not carried on. When the shield machine is in curve alignments, rotation rectification is also not carried on. To investigate the reasons that cause the rotation situation, the shield rotation moment model must be established.Fig. 2. Rotation rectification steps3 Modeling of the Shield Rotation Moment The loads acting on the shield are composed of four forces: force due to the selfweight of the shield F1, force due to the jack thrust F2 , force acting at the face F3 , and force acting on the shield periphery F4 , as illustrated in Fig. 3. Corresponding to the forces, the moment around the shield axis are T1 , T2 , T3 and T4 respectively.Fig. 3. Shield loads3.1 1 T Corresponding to the Shield Self-weight F1 The point of the self-weight is on the shield axis, so there is not any moment around shield axis. That means T1 = 0 .3.2 2 T Corresponding to the Jack Thrust F2 The force 2 F is composed of jack thrust F21 and friction on the interface between the jacking plate and the segment F22 . The direction of F21 is parallel to shield axis, so there is not any moment around shield axis. The force F22 produces moment around shield axis.（1）（2）（3） where js is the ratio of resistance to friction between jack and segment6,7; js is the coefficient of mobilized friction between jack and segment; ji f is the ith jack thrust force; i is the angle between the ith jack and q axis; sign(CF) a positive sign for counterclockwise rotation of cutter face (viewed from shield tail). Then（4） Where r is the radius of the jack from the r axis.3.3 3 T Corresponding to the Force Acting at the Shield Face F 3 (5) Where F31 is the force due to the earth pressure acting on the panel of cutter face; F32 is the force due to the muck in the chamber; F33 is the force due to the earth pressure acting on the edge of the cutter face and F34 is the cutting force.3.3.1 The Force Due to the Earth Pressure Acting on the Panel of Cutter Face F31 According to soil mechanics8,9: （6） Where is the earth pressure on the cutter face panel; K0 is the horizontal earth pressure coefficient; is soil bulk density; h is the vertical depth of the integrated area of cutter face from the ground surface. （7） Where r is the radius of cutter face; H is the vertical depth of the center of cutter face from the ground surface. Then the normal earth pressure 31 （8） Where is the cutter face open rate; ms is the coefficient of mobilized friction between muck and shield; D is the cutter face diameter. Then （9）3.3.2 The Force Due to the Soil in the Chamber F32 The forces due to the soil in the chamber concerning to the shield rotation include friction forces between the soil with the bulk, with shield cylindrical inner face and with the rear of cutter face. In this paper, only the friction force between the muck with the rear of cutter face is taken into account. Then （10）3.3.3 The Force Due to the Earth Pressure Acting on the Edge of the Cutter Face F33 （11） Then （12）Where lce is the cutter face thickness.3.3.4 The Cutting Force F34，that is （13），that is （14） There by N0 ， N1 are obtained. Then the cutting force of one knife F t is, （15） Where S c is the soil rupture area. （16） Where P is the cutting depth of specific cutter, e l is the width of cutter.Fig. 5. The cutting force model （17） Where is the internal friction angle of the soil. （18） Where v is the shield propulsion speed, n is the cutter face rotation velocity, m is the number of cutter at the same assembly radius. （19） Where ir is the ith cutter assembly radius. i a =1 for active cutter and 0 for inactive cutter.3.4 T4 Corresponding to the Force Acting on the Shield Periphery F4 As to 4 F , a simplified method is introduced. （20） Where D is the diameter of the shield, L is the length of the shield, f is the fiction on unit shield periphery area. （21） （22） （23） Equilibrium that keep the Rotation balance （24） where ms is the ratio of resistance to friction between shield and soil around shield.4 Conclusion Concerning T1 = 0 , the equilibrium that keep the Rotation balance is （25） The hindering moments of shield rotation are T2 and T4 . The moment that causing shield rotation is T3 . T2 and T4 are passive moment, and T3 is positive moment.Under normal circumstance, the moments that provided by T2 and T4 are much larger than T3 , so the shield keep un-rotation. T2 is proportional to jack thrust force. T4 is relative to characteristic of soil around the shield. T3 is relative to characteristic of soil front of the shield, shield machine propulsion speed and cutter face rotation velocity. T3 , especially T34 , changes acutely with the actual working conditions. With the increasing of the T34 , the possibility of shield rotation goes high. For instance, cutting large stones, excavating from sand to clay and increasing the propulsion speed will increase T34 .5 Rotation Rectification Practice After the measurement of inclinometer, if 0.5and 1.5, then rotation rectification could not be carried on. In this situation, the reason causing the rotation deviation must be concerned. If the rotation is due to cutting the large stones in front of the shield, then the excavation parameters should remain unchanged. If the rotation is due to that the shield is in the process from sand to clay, then the ratio of cutter face rotation velocity to shield propulsion speed should be increased to prevent further rotation. If 1.5 , then the rotation rectification should be carried on. If the rotation is due to cutting the large stones in front of the shield, then the excavation parameters should remain unchanged and rotation rectification by counter rotation of cutter is needed. If the rotation is due to that the shield is in the process from sand to clay, then the ratio of cutter face rotation velocity to shield propulsion speed should be decreased and rotation rectification by counter rotation of cutter is needed. After the rectification is done, the ratio of cutter face rotation velocity to shield propulsion speed should be adjusted to prevent over rectification. In curve alignments, the friction between shield and the soil around the shield increase, so the possibility of rotation gets smaller. But when the shield machine is in curve alignments, rotation rectification is not carried on, so the inclinometer values should be observed closely the inclinometer values, and the excavation parameters should be kept well, to prevent over rotation.Acknowledgments. We thank the Chinese National Basic Research Program (973 Program) (No.2007CB714006) for the financial support of this investigation.2.中文转动力矩的分析及姿态的矫正盾构机的策略摘要：盾构机在实际工作的过程中经常发生盾体滚动的现象，这会导致盾构机在工作中出现偏差，同时也增加了控制盾构机的难度。这种现象的产生主要是由于刀头的旋转引起的。基于这个实际的问题，我们对盾体以及刀盘的受力进行研究。同时，正反转控制技术被开发用于控制盾构机的旋转偏离角度。这些研究成果为盾构机整体姿态矫正的研究提供了理论依据。关键词：盾构机，转动力矩分析，纠正策略。1. 引言1.1盾构法盾构机是在基本建设与资源开发中的重要设备，它被广泛用于隧道、铁路、公路、矿山等地下领域。盾构法是一种利用盾构机的隧道施工方法。在盾构掘进的过程中，盾尾处的千斤顶推动隧道管片，利用其产生的反作用力推动盾构机向前掘进，同时必须保持开挖面的稳定。 与明挖法相比，盾构法有以下几种有点：1. 地表的占用面积少，减少了土地租用的成本。2. 受天气的影响较小，因此有相对更长的有效施工时间。3. 软土、砂卵土、软质岩以及岩层都适用。4. 施工速度快。5. 对环境的影响小。根据以上的优点，盾构法得到了广泛的应用。1.2旋转姿态矫正在盾构挖掘的过程中，盾构机的位置与姿势对隧道施工的精度十分重要。但一定会出现偏离于实际或所需的位置与姿态的情况，因此修正偏差是十分重要的。本文中，我们不讨论盾构机位置的矫正。对于姿态矫正，只考虑旋转矫正。盾构机姿态由三个参数来描述：俯仰角p，偏转角y，和旋转角r。俯仰角是盾构机的轴线与水平面的夹角。偏转角是盾构机与通过盾构机轴线的垂直面的夹角。旋转角是盾构机在盾构机轴线上旋转的角度。在下面的说明中，用替代p。为了说明，建立如下坐标系。图1 所建立的坐标系所建立的整体坐标系CE的z轴垂直向下，x轴和y轴在水平面上。x、y和z轴相互两两垂直同时符合右手定则。建立一个机器坐标系CM的，当盾构机没有旋转时，它的p轴垂直向下，r轴沿着盾构机的轴线方向。CM与盾构机两者合在一起。机器坐标系的远点被选择在盾构机盾尾平面的中心。同时p、q和r三轴两两垂直且遵循右手定则。建立参考坐标系，选择pv轴沿着在平面PV与盾尾平面的交线方向，rv轴沿着盾构机的轴线方向，pv轴与qv轴都在盾尾平面上。平面PV是穿过盾构机轴线的垂直面。参考坐标系的原点在盾尾平面的中心处。rv、pv与qv三轴两两垂直且遵循右手定则。pv轴与p轴的夹角为旋转角，盾构机逆时针旋转时角为正（从盾尾的方向上看）。盾构机旋转姿态矫正的目的是使值保持为零。在盾构机挖掘的过程中，如果值不等于零，千斤顶实际的推力分布与理论上的推理分布不相同，这会导致运算出现偏差。更严重的是当超过规定的临界值时会导致盾构机的推力不足和管片拼装的失败。1.3 先前研究在文献1中，以上海地区的泥沙地为基础，在测试中结合不同的盾构机参数与土壤特性。在实验结果的基础上，此课题的目的是发现推力的变化规律、土壤与盾构机之间的摩擦机理与它的影响因素。在文献2中，将泥土的切削力作为研究对象并提供了一个泥土切削力模型。在文献3,4,5中，通过利用数学与力学的方法对土压平衡盾构机的工作装置进行研究，找出合理的计算轴向力的方法和它的影响因素。为了研究盾构机的旋转姿态矫正，一定要建立一个盾构机的转动力矩模型。先前研究将有助于建立模型，但并没有专门这方面的研究资料。2. 旋转矫正方案旋转矫正方案包括以下四个步骤：旋转角的测量，原因分析，判断是否需要矫正和旋转矫正。旋转角可以通过盾构机中的倾角计进行测量。在盾构机转动力矩的模型上，可以找到引起当前旋转情况的原因。如果1.5，则需要切割机逆向转动进行旋转矫正。当p与y进行矫正的过程中，旋转矫正将不能进行。当盾构机在其行进路线为曲线的阶段，旋转矫正也不能进行。为了调查引起转动现象的原因，必须建立盾构机的转动力矩模型。图2 旋转矫正步骤3. 盾构机旋转力矩模型盾构机所受到的力由四种力组成：盾构机的自身重力F1，千斤顶的推力F2，刀盘正面压力F3和周向压力F4，如图3所示。对应各个受力，盾构机受到的力矩分别为T1，T2，T3和T4。图3 盾构机受力图3.1 T1对应于盾构机自身重力F1盾构机自重的作用点在盾构机自身的轴线上，因此不产生力矩，则T1=0。3.2 T2对应于盾构机千斤顶推