Based on the similarity theory,a tunnel excavation simulation testing system under typical unsymmetrical loading conditions was established.Using this system,the failure mechanism of surrounding rock of shallow-bias t...Based on the similarity theory,a tunnel excavation simulation testing system under typical unsymmetrical loading conditions was established.Using this system,the failure mechanism of surrounding rock of shallow-bias tunnels with small clear distance was analyzed along with the load characteristics.The results show that:1) The failure process of surrounding rock of shallow-bias tunnels with small clear distance consists of structural and stratum deformation induced by tunnel excavation; Microfracture surfaces are formed in the tunnel surrounding rock and extend deep into the rock mass in a larger density; Tensile cracking occurs in shallow position on the deep-buried side,with shear slip in deep rock mass.In the meantime,rapid deformation and slip take place on the shallow-buried side until the surrounding rocks totally collapse.The production and development of micro-fracture surfaces in the tunnel surrounding rock and tensile cracking in the shallow position on the deep-buried side represent the key stages of failure.2) The final failure mode is featured by an inverted conical fracture with tunnel arch as its top and the slope at tunnel entrance slope as its bottom.The range of failure on the deep-buried side is significantly larger than that on the shallow-buried side.Such difference becomes more prominent with the increasing bias angle.What distinguishes it from the "linear fracture surface" model is that the model proposed has a larger fracture angle on the two sides.Moreover,the bottom of the fracture is located at the springing line of tunnel arch.3) The total vertical load increases with bias angle.Compared with the existing methods,the unsymmetrical loading effect in measurement is more prominent.At last,countermeasures are proposed according to the analysis results: during engineering process,1) The surrounding rock mass on the deep-buried side should be reinforced apart from the tunnel surrounding rock for shallow-buried tunnels with small clear distance; moreover,the scope of consolidation should go beyond the midline of tunnel(along the direction of the top of slope) by 4 excavation spans of single tunnel.2) It is necessary to modify the load value of shallow-bias tunnels with small clear distance.展开更多
Purpose:To evaluate the clinical efficacy and safety of sulcus transscleral intraocular lens suture fixation with small incision through scleral tunnel in eyes the with posterior capsule defect or insufficient zonula ...Purpose:To evaluate the clinical efficacy and safety of sulcus transscleral intraocular lens suture fixation with small incision through scleral tunnel in eyes the with posterior capsule defect or insufficient zonula support. Methods:Thirty nine eyes with severe posterior capsule defect and zonula damages caused by small-incision cataract surgery,and those with capsule absence or intraocular lens dislocation were selected in this investigation from February 2007 to December 2009.Sulcus transscleral intraocular lens suture combined with puncture needle-guided external approach and."one- or two-point fixation" method in the small sclera tunnel incision were employed. Results:The mean follow-up was 12.1 months (range from 3 to 28 months). Six eyes were complicated by some eye diseases postoperatively.The best-corrected visual acuity was 20/40 or better in other 34 eyes.(87.17%).All eyes with secondary IOL fixation presented equal or better naked visual acuity than best-corrected visual acuity best-corrected preoperatively.No intraoperative and postoperative complications such as hemorrhage, retinal detachment, intraocular lens tilt and decentration occurred. Conclusion:Sulcus transscleral intraocular lens suture fixation via small sclera tunnel incision was easy to operate and master,required less operative time,and made primary intraocular lens fixation more effective in eyes with posterior capsule defect or insufficient zonula support in small sclera tunnel incision surgery.In addition,the technique was safe and effcacious for secondary intraocular lens fixation.展开更多
With the increasing traffic demand, the closely built three or more tunnels with large section play a significant role in the tunnel construction. However, the interaction among tunnels has important influences on the...With the increasing traffic demand, the closely built three or more tunnels with large section play a significant role in the tunnel construction. However, the interaction among tunnels has important influences on the security and economy of tunnel engineering, and the calculation of pressure from the surrounding rock during the excavation is one of the problems that need to be solved urgently. Based on the practical engineering of three tunnels, the load model of three tunnels was proposed in consideration of the interaction and excavation sequence between tunnels. In comparison with the load model of single tunnel, the construction mechanical characteristics of the three tunnels were analyzed. The results show that the rock pressure of three tunnels calculated by the current tunnel design code is not reliable, and the interaction force increases with the spacing between tunnels.展开更多
针对高速公路隧道内光线昏暗、图像受灯光影响及远距离小目标检测困难等问题,提出了一种改进的YOLOv5高速公路隧道车辆和人员检测算法。首先,使用高斯混合聚类来获得更加匹配数据集目标的一组锚框,提高了模型的检测精度;其次,在特征融...针对高速公路隧道内光线昏暗、图像受灯光影响及远距离小目标检测困难等问题,提出了一种改进的YOLOv5高速公路隧道车辆和人员检测算法。首先,使用高斯混合聚类来获得更加匹配数据集目标的一组锚框,提高了模型的检测精度;其次,在特征融合部分引入内容感知重组特征(content-aware ReAssembly of FEatures, CARAFE)上采样算子,扩大感受野,降低上采样过程特征细节损失;最后,通过向网络中插入坐标注意力(coordinate attention, CA),进一步增强模型对图像各位置特征的提取能力。为验证算法的有效性,在浙江温丽高速公路隧道数据集上进行实验,结果表明:所提算法的平均检测精度(mean average precision, mAP)达到了95.7%,较原模型提升3.8%,对于远距离小目标和受严重灯光影响的目标能够实现更加精准检测,为复杂环境下高速公路隧道内车辆和人员检测提供了一种有效的解决方案。展开更多
基金Project(51508575)supported by the National Natural Science Foundation of ChinaProject(2011CB013802)supported by the National Basic Research Program of China+1 种基金Projects(2014M560652,2016T90764)supported by the China Postdoctoral Science FoundationProject(2015RS4006)supported by the Innovative Talents of Science and Technology Plan of Hunan Province,China
文摘Based on the similarity theory,a tunnel excavation simulation testing system under typical unsymmetrical loading conditions was established.Using this system,the failure mechanism of surrounding rock of shallow-bias tunnels with small clear distance was analyzed along with the load characteristics.The results show that:1) The failure process of surrounding rock of shallow-bias tunnels with small clear distance consists of structural and stratum deformation induced by tunnel excavation; Microfracture surfaces are formed in the tunnel surrounding rock and extend deep into the rock mass in a larger density; Tensile cracking occurs in shallow position on the deep-buried side,with shear slip in deep rock mass.In the meantime,rapid deformation and slip take place on the shallow-buried side until the surrounding rocks totally collapse.The production and development of micro-fracture surfaces in the tunnel surrounding rock and tensile cracking in the shallow position on the deep-buried side represent the key stages of failure.2) The final failure mode is featured by an inverted conical fracture with tunnel arch as its top and the slope at tunnel entrance slope as its bottom.The range of failure on the deep-buried side is significantly larger than that on the shallow-buried side.Such difference becomes more prominent with the increasing bias angle.What distinguishes it from the "linear fracture surface" model is that the model proposed has a larger fracture angle on the two sides.Moreover,the bottom of the fracture is located at the springing line of tunnel arch.3) The total vertical load increases with bias angle.Compared with the existing methods,the unsymmetrical loading effect in measurement is more prominent.At last,countermeasures are proposed according to the analysis results: during engineering process,1) The surrounding rock mass on the deep-buried side should be reinforced apart from the tunnel surrounding rock for shallow-buried tunnels with small clear distance; moreover,the scope of consolidation should go beyond the midline of tunnel(along the direction of the top of slope) by 4 excavation spans of single tunnel.2) It is necessary to modify the load value of shallow-bias tunnels with small clear distance.
基金Science and technology project of Fujian Province(2008F3031)
文摘Purpose:To evaluate the clinical efficacy and safety of sulcus transscleral intraocular lens suture fixation with small incision through scleral tunnel in eyes the with posterior capsule defect or insufficient zonula support. Methods:Thirty nine eyes with severe posterior capsule defect and zonula damages caused by small-incision cataract surgery,and those with capsule absence or intraocular lens dislocation were selected in this investigation from February 2007 to December 2009.Sulcus transscleral intraocular lens suture combined with puncture needle-guided external approach and."one- or two-point fixation" method in the small sclera tunnel incision were employed. Results:The mean follow-up was 12.1 months (range from 3 to 28 months). Six eyes were complicated by some eye diseases postoperatively.The best-corrected visual acuity was 20/40 or better in other 34 eyes.(87.17%).All eyes with secondary IOL fixation presented equal or better naked visual acuity than best-corrected visual acuity best-corrected preoperatively.No intraoperative and postoperative complications such as hemorrhage, retinal detachment, intraocular lens tilt and decentration occurred. Conclusion:Sulcus transscleral intraocular lens suture fixation via small sclera tunnel incision was easy to operate and master,required less operative time,and made primary intraocular lens fixation more effective in eyes with posterior capsule defect or insufficient zonula support in small sclera tunnel incision surgery.In addition,the technique was safe and effcacious for secondary intraocular lens fixation.
基金Project(2011CB01380) supported by the National Basic Research Program of ChinaProject(51178468) supported by the National Natural Science Foundation of ChinaProject(2011G013-B) supported by Science and Technology Development of Railways Department in China
文摘With the increasing traffic demand, the closely built three or more tunnels with large section play a significant role in the tunnel construction. However, the interaction among tunnels has important influences on the security and economy of tunnel engineering, and the calculation of pressure from the surrounding rock during the excavation is one of the problems that need to be solved urgently. Based on the practical engineering of three tunnels, the load model of three tunnels was proposed in consideration of the interaction and excavation sequence between tunnels. In comparison with the load model of single tunnel, the construction mechanical characteristics of the three tunnels were analyzed. The results show that the rock pressure of three tunnels calculated by the current tunnel design code is not reliable, and the interaction force increases with the spacing between tunnels.
文摘针对高速公路隧道内光线昏暗、图像受灯光影响及远距离小目标检测困难等问题,提出了一种改进的YOLOv5高速公路隧道车辆和人员检测算法。首先,使用高斯混合聚类来获得更加匹配数据集目标的一组锚框,提高了模型的检测精度;其次,在特征融合部分引入内容感知重组特征(content-aware ReAssembly of FEatures, CARAFE)上采样算子,扩大感受野,降低上采样过程特征细节损失;最后,通过向网络中插入坐标注意力(coordinate attention, CA),进一步增强模型对图像各位置特征的提取能力。为验证算法的有效性,在浙江温丽高速公路隧道数据集上进行实验,结果表明:所提算法的平均检测精度(mean average precision, mAP)达到了95.7%,较原模型提升3.8%,对于远距离小目标和受严重灯光影响的目标能够实现更加精准检测,为复杂环境下高速公路隧道内车辆和人员检测提供了一种有效的解决方案。
