基于螺栓接头受力性能的盾尾注浆压力控制

Pressure Control Analysis Based on Mechanical Properties of Bolts During Grouting at Shield Tail

摘要:

对采用螺栓接头的管片，管片间接头主要靠两种效应，即端面摩擦效应及螺栓抗剪效应，来平衡注浆压力对管片接头的剪切，认为端面摩擦效应主要在管片发生相对位移前发生作用，之后则螺栓抗剪效应是主要的.通过引入等效空隙率替代土体本身的空隙率来考虑建筑间隙的影响，对盾尾注浆情况下因注浆而对管片造成的压力进行了理论推导，得到注浆对管片产生的压力计算式.结果表明：注浆对管片产生的压力，随注浆时间的增长、注浆压力的增大而增大.将接头螺栓的抗剪效应与注浆对管片产生的压力结合起来，据接头螺栓的剪切破坏条件来控制注浆压力和注浆时间，即在求得注浆压力产生的螺栓剪应力前提下，要求该剪应力小于螺栓的许用剪应力，从而实现对注浆压力及注浆时间的控制.

Abstract:

As to segments joined by bolts, two kinds of friction forces between segments and shear resistance of bolts are in balance with shear force produced by grouting pressure. It is believed that the friction force between segments takes effect before segments displacement happens, while shear resistance of bolts would be dominating afterward. The pressure acting on shield tunnel segments during grouting at the tail was studied by substituting the intrinsic void percentage with the equivalent void percentage of the soil to assess the influence of construction gap. Based on such a theory and derivation, a formula to calculate the pressure was established. It shows that the pressure on segments increases with the increasing of grouting pressure and grouting time period. By combining shear resistance of bolts with the pressure acting on the segments, the grouting pressure and time could be controlled by shear stress of the bolts,which indicates that with the shear stress determined,the shear stress should be less than the allowable stress so as to control the grouting pressure and time.