监控量测在浅埋地下大断面平顶框架结构施工中的应用分析

城市浅埋大断面地下结构因其结构和建设的复杂性往往成为工程建设的重点和难点。施工中如何利用监控量测技术实时监控围岩、支护结构、中间构造结构等之间的受力转换往往成为施工关键。结合北京城市快速轨道交通东直门车站地下方厅工程实例,探讨和分析了应用浅埋平顶群洞暗挖法施工过程中监控量测技术和方法,并对监测结果进行了比较分析,验证了施工方法的合理有效性。     

考虑中间主应力影响时的圆筒形孔扩张问题的弹塑性解

Tresca强度理论、Mohr-Coulomb强度理论在求解圆筒形孔扩张问题时的弹塑性解并没有考虑中间主应力的影响。本文首次考虑中间主应力影响时求解圆筒形孔扩张问题的弹塑性解。计算表明考虑中间主应力时圆筒形孔的塑性区半径有明显减少。据此可以充分发挥岩土体自身的承载能力，对岩土工程有重要意义。     

DX多节挤扩桩的产生及特点

介绍了一种挤孔式变截面桩———DX多节挤扩桩及DX挤扩装置 ,详细地比较了DX挤扩装置与YZJ型支盘挤扩机的技术性能 ,此外还介绍了DX桩的特点     

轴拉力作用下异形截面多腔钢管混凝土巨型分叉柱抗震性能试验研究

针对某超高层建筑巨型柱在罕遇地震作用下轴向受拉的情况,研究了异形截面多腔钢管混凝土巨型分叉柱抗震性能,考虑水平力作用方向和分叉界面下一层构造的影响,进行了4个模型试件的低周反复荷载试验。试验结果表明：分叉柱的破坏大多发生在截面突变的分叉界面处,其水平力-位移角滞回曲线饱满程度一般,但无明显捏拢现象;分叉柱均出现了承载能力退化现象;分叉柱的变形和耗能主要在上柱部分,并随位移的增大,所占比例提高;较沿截面短轴方向加载,沿截面长轴方向加载时分叉柱的抗震性能明显提高;分叉界面下一层增加腔体加强的分叉柱较未加强分叉柱的承载力提高16.6%~29.7%,极限位移角增大13.1%~13.2%,位移角为1%时综合耗能提高10.0%~16.7%。     

Stress singularity analysis in the restorations of premolar class ii cavities

Abstract

This paper presents the singular stress analysis near the apex of a structure formed during dental restoration of a premolar class II cavity. Based on the elasticity theory, the stresses may go to infinity at the junctions of different materials (e.g. dentine, enamel, restoration materials). Tensions will cause material separation and then material fracture. In order to reduce the failure probability, the degree of stress concentration has to be reduced. The stress singularity order and the stress intensity factor are two parameters, which are often used in fracture analysis. The objective of this paper is to find conditions such that non‐singular stress fields are possible. Three critical positions in the restoration structure are discussed.

They are the tips of interface between (1) enamel and restoration; (2) dentine and restoration; and (3) enamel, dentine and restoration. In the last two cases, the restoration may be bonded or debonded to enamel or dentine. After employing Kolosov‐Muskhelishvili complex functions together with the eigenfunction expansion method, the singularity orders are computed theoretically. Weak stress singularity conditions can be sought by properly selecting cutting angles or restoration materials.     

大新锰矿复杂空区群三维数值模型构建方法及胶结充填治理研究

矿山岩土工程数值分析中研究复杂空区群三维数值模型构建方法对空区治理具有现实意义。为精确分析矿山地下工程围岩移动和应力变化规律，特别是不同采矿方法形成的复杂空区的稳定性和矿柱应力变化，提出了3DMine-Surfer-Rhino-ANSYS-FLAC3D多软件联合建模方法，解决了复杂空区群三维数值模型构建和大数量小尺寸矿房矿柱网格剖分问题。以广西大新锰矿矿体开采为案例，构建了留矿法与房柱法形成的采空区的三维数值模型，模拟分析空区的稳定性和决策胶结充填治理方案。研究结果表明：（1）大新锰矿留矿法开采的空区部分顶柱有垮落风险；（2）房柱法开采的空区部分矿柱变形大，有塑性破坏；（3）对于胶结充填留矿法的空区，隔一充一充填方案治理效果更好，在治理初期地表沉降更小。     

Changes in Coupled Vibration Frequencies and Modes of Wall-Cavity Systems Induced by Stiffness Variation in the Structure

Problems of fluid structure interactions are governed by a set of fundamental parameters. This work aims at showing through simple examples the changes in natural vibration frequencies and mode shapes for wall-cavity systems when the structural rigidity is modified. Numerical results are constructed using ANSYS software with triangular finite elements for both the fluid （2D acoustic elements） and the solid （plane stress） domains. These former results are compared to proposed analytical expressions, showing an alternative benchmark tool for the analyst. Very rigid wall structures imply in frequencies and mode shapes almost identical to those achieved for an acoustic cavity with Neumann boundary condition at the interface. In this case, the wall behaves as rigid and fluid-structure system mode shapes are similar to those achieved for the uncoupled reservoir case.     

腔耦合双J-C模型中原子纠缠的猝灭和猝生

研究了腔间有耦合的双J-C模型中原子纠缠的动力学, 分析了腔间耦合系数A和原子的初态对原子纠缠的猝灭(ESD)和猝生(ESB)的影响. 通过对原子间共生纠缠度的数值分析发现, 当原子初态为第一类类Bell态时, 不会出现ESD和ESB, 腔间的耦合可使原子的纠缠加大, 并能使初态为分离态的原子产生纠缠. 当原子初态为第二类类Bell态时, A的大小可改变出现ESD与ESB的时间间隔, 或决定是否出现ESD, 但腔间的耦合不能使初态不纠缠的原子产生纠缠.