沉管隧道新型剪力杆组合结构的抗剪应用研究

为了提高节段接头施工效率和沉管隧道预制化水平,改善现有节段接头连接方案存在的接头截面利用率低、中埋式止水带安装困难、工效低和剪力键浇筑质量差等突出问题,提出以新型钢剪力杆组合结构替代传统剪力键的节段接头连接方案。通过开展剪力杆组合结构单杆、多杆剪切试验,测量剪切荷载、接头相对错动、钢套筒应变和钢筋应力,研究其抗剪性能。以大连湾海底沉管隧道工程为依托,基于材料塑性损伤本构模型,考虑节段接头的细部构造,根据剪力杆组合结构剪切试验对数值仿真方法的有效性进行验证。利用数值模拟研究了节段接头水平向、竖直向剪切,绕横轴、竖轴弯曲的变形规律和破坏特征,进一步建立三维仿真模型,研究剪力杆组合结构在大连湾海底沉管隧道工程中的工作情况。研究结果表明:剪力杆组合结构的失效由剪力杆的剪断破坏控制,破坏延性特征明显。剪力杆破坏荷载-位移关系可以分为弹性、塑性加强和塑性破坏3个阶段。接头存在间隙时,剪力杆组合结构破坏屈服特征明显。剪切试验数值结果与现场试验结果吻合良好。节段接头数值试验揭示,在剪切、弯曲作用下接头破坏过程较为复杂,且均呈现出阶段性特征。基于接头损伤分析,提出了节段接头位移安全评价指标。对控制工况下的三维全长数值模型的节段接头计算位移指标进行安全评价,评价结果显示,剪力杆组合结构适用于大连湾海底沉管隧道工程并具有良好的经济性。

剪力静定杆的转动刚度和传递系数

无剪力分配法中剪力静定杆的转动刚度和传递系数的推导计算是较难理解的部分,采用两种方法推导了剪力静定杆的转动刚度和传递系数,并用计算实例进行了验证。推导过程,简单明了,便于理解,使学生可以更好的掌握和应用。

结构力学位移法解题方法研究

位移法作为一种求解超静定结构问题的方法,在结构力学中具有举足轻重的地位。本文对用位移法解具有剪力静定杆的超静定问题的方法进行了研究,并对现有方法中存在的问题进行改进。

沉管隧道结构抗震性能试验研究

结构物的抗震性能是判断其安全性和稳定性的重要指标。大连湾海底隧道工程中,沉管结构的应用环境较为复杂,其在地震灾害下安全性的分析研究对工程设计、施工和运营具有较大实际意义。文章分别通过数值模拟方法和荷载试验对沉管隧道结构的抗震性能开展试验分析。试验结果表明,现有工程设计方案具有很好的抗震性能,在复杂受力情况下能够保证隧道结构的稳定性和安全性。

绘制内力图的方法及其在实际工程中的应用

本文阐述了利用杆端弯矩、杆端剪力、杆端轴力三者之间的关系来绘制内力图。这种方法不仅使用于静定结构的梁与刚架,而且也使用于超静定结构的梁与刚架,在超静定结构中它的优点更为突出,因此在工程实际中有着广泛的应用。

A new analytical solution for calculation the displacement and shear stress of fully grouted rock bolts and numerical verifications

In presence of difficult conditions in coal mining roadways, an adequate stabilization of the excavation boundary is required to ensure a safe progress of the construction. The stabilization of the roadways can be improved by fully grouted rock bolt, offering properties optimal to the purpose and versatility in use. Investigations of load transfer between the bolt and grout indicate that the bolt profile shape and spacing play an important role in improving the shear strength between the bolt and the surrounding strata. This study proposes a new analytical solution for calculation displacement and shear stress in a fully encapsulated rock bolt in jointed rocks. The main characteristics of the analytical solution consider the bolt profile and jump plane under pull test conditions. The performance of the proposed analytical solution, for three types of different bolt profile configurations, is validated by ANSYS software. The results show there is a good agreement between analytical and numerical methods. Studies indicate that the rate of displacement and shear stress from the bolt to the rock exponentially decayed. This exponential reduction in displacement and shear stress are dependent on the bolt characteristics such as: rib height, rib spacing, rib width and grout thickness, material and joint properties.

Introducing aggregate into grouting material and its influence on load transfer of the rock bolting system

A fully grouted bolt provides greater shear load capacity for transmitting the load from the rock to the bolt, and vice versa. When grout fills irregularities between the bolt and the rock, a keying effect is created to transfer the load to the bolt via shear resistance at the interface and within the grout. Previous research has revealed that the mechanical properties of the grout had a great impact on the load transfer capacity of the rock bolting system. This paper presents a method to enhance the rock bolting strength by introducing metal granules into the grouting material. Experimental results suggest that both the average peak load of pullout tests and the total energy absorption of the system will increase if some metal granules are mixed into the resin.

框架柱侧移刚度的计算方法比较

本文就框架柱侧移刚度的两种常见算法——根据杆件的受力特征计算和根据杆件柔度和刚度的对应关系计算,在对杆端约束条件、对变截面杆件的灵活处理上予以分析和比较。同时就框架柱在常见的杆端约束条件下,侧移刚度的计算式进行了归纳。