深中通道沉管临时锚拉系统横向偏位模型试验

Lateral deviation model test of temporary anchorage system for immersed tube in Shenzhen-Zhongshan Link

为探明深中通道沉管对接施工时锚拉系统的横向偏位限值,利用数值模拟和模型试验相结合的方法研究了锚拉系统的变位能力,建立了锚拉系统的有限元模型,基于有限元分析结果确定了足尺模型试验的加载分级标准;基于锚拉系统的实际受力状态确定了拉杆轴向荷载等级,试验模拟了水平及竖向各5 cm的初始安装偏差,分4个工况对结构进行了加载并测试了应力与偏位。研究结果表明:在给定拉杆轴向荷载下,随着横向偏位的增加,锚拉系统的安全储备均逐渐减小;单根拉杆在轴向试验荷载1 000 kN作用下,横向偏位为5 cm时,结构处于弹性工作状态,锚板和肋板最大Mises应力分别达到190.8和179.3 MPa,距其设计强度295和280 MPa分别具有35.3%和36.0%的安全储备;在1.2和1.5倍轴向试验荷载下,施加横向偏位至5 cm时,锚拉系统仍处于弹性工作状态,锚板和肋板最大Mises应力分别从221.1和196.8 MPa升至286.8和260.5 MPa,设计安全储备平均值由27.4%降至5.0%,拉杆最大应力从473.8 MPa升至623.7 MPa,屈服安全储备由43.3%降至25.3%;极限侧推试验中,在1.5倍轴向试验荷载下,当横向偏位为6 cm时,锚板达到设计强度,继续增大至12.8 cm时,锚板率先屈服,认为该锚拉系统已失效,此时拉杆应力为704.8 MPa,屈服安全储备为15.6%,故建议沉管水下对接施工的横向偏位控制值为6 cm。

To find out the lateral deviation limit of the anchorage system during the jointing construction of the immersed tube in Shenzhen-Zhongshan Link,the displacement ability of the anchorage system was studied by the combination of numerical simulation and model test.The finite element model of the anchorage system was established,and the loading grading standard of the full-scale model test was determined based on the finite element analysis results.In view of the actual stress state of the anchorage system,the axial load grade of the tie rod was determined.The test simulated the initial installation deviations of 5 cm in horizontal and vertical directions,and the structure was loaded in four working conditions.In addition,the stress and displacement were tested.Research results show that under the given axial load of the tie rod,the safety reserve of the anchorage system decreases gradually with the increase in the lateral deviation.Under the axial test load of 1000 kN of a single tie rod and the lateral deviation of 5 cm,the structure is in an elastic working state,and the maximum Mises stresses of the anchor plate and rib plate reach 190.8 and 179.3 MPa,respectively.The safety reserves relative to their design strengths of 295 and 280 MPa are 35.3%and 36.0%,respectively.Under 1.2 and 1.5 times of the axial test load,when the lateral deviation is applied to 5 cm,the anchorage system is still in an elastic working state.The maximum Mises stresses of the anchor plate and rib plate increase from 221.1 and 196.8 MPa to 286.8 and 260.5 MPa,respectively.The average designed safety reserve decreases from 27.4%to 5.0%.The maximum stress of the tie rod increases from 473.8 MPa to 623.7 MPa,and the yield safety reserve decreases from 43.3%to 25.3%.In the limit lateral deviation test,under 1.5 times of the axial test load,the anchor plate reaches the designed strength when the lateral deviation is 6 cm.When it continues to increase to 12.8 cm,the anchor plate yields first,and it is considered that the anchorage system has failed.At this time,the stress of the tie rod is 704.8 MPa,and the yield safety reserve is 15.6%.Therefore,it is recommended that the lateral deviation control value of immersed tubes should be 6 cm during the underwater jointing construction.