基于支护结构强度和变形综合优化的隧道支护理论与方法

针对新奥法在工程应用中的不足,分析了采用经典地压理论解决隧道工程支护问题的合理性与缺陷,提出了基于支护控制曲线、工程地质情况、监测数据的闭环式目标控制优化支护理论.通过有限元法分析不同应力释放率下支护结构应力与围岩变形的关系,利用支护应力与围岩变形控制条件确定目标控制位移,通过计算后续步段开挖对变形影响的修正控制位移,并结合实际工程的现场位移监测数据,最终确定合理的二次支护施作条件.通过工程实例,验证了该方法的正确性与实用性.

浅谈软土盾构隧道施工理论及其实践分析

随着经济的发展和社会进步,交通建设事业蓬勃发展。近年来,轨道交通工程建设数量越来越多,规模越来越大,许多新材料、新技术以及新工艺也逐渐应用到轨道施工中,在一定程度上提高了轨道交通工程施工安全质量。在轨道交通工程施工过程中,软土盾构隧道施工技术属于一种新型施工技术,其理论发展还不够成熟,需要相关技术人员、专家等在实践中不断研究与完善。文章结合工程实例,对软土盾构隧道理论及其实践进行了具体分析,并且介绍了三重管旋喷桩施工技术及软土盾构施工控制措施,希望能为相关行业提供有益参考。

纵向裂缝对隧道钢筋混凝土衬砌结构影响的试验

基于荷载-结构模型,开展了钢筋混凝土衬砌的加载试验.通过分析钢筋混凝土衬砌加载过程中结构的变形和裂缝展开规律,获得了纵向裂缝深度与结构转动刚度的关系曲线,提出了单一裂缝情况下钢筋混凝土衬砌的计算模型.该模型根据连接弹簧单元来模拟衬砌裂缝,弹簧单元的参数根据衬砌结构试验结果和理论分析确定.通过该模型得到的承载安全系数可以评价带裂缝衬砌是否需要进一步加固,对实际隧道工程具有指导意义.

考虑围岩应变软化与剪胀效应的深埋隧道合理支护时机分析

为确保隧道稳定、节约成本,针对围岩应变软化与剪胀效应下深埋隧道的合理支护时机,基于隧道约束收敛理论,提出围岩-支护作用2阶段分析思路,引入初期支护屈服轴力与围岩变形折减率作为合理支护时机的判据。采用三维有限差分软件求解初期支护屈服轴力与围岩变形折减率,分析不同围岩质量、支护类型、初始应力、临界塑性软化系数、剪胀角下围岩预留变形量范围,确定深埋隧道合理支护时机。结果表明:1)岩体质量与初始应力对隧道合理支护时机影响较为显著,但岩体峰后剪胀与应变软化特性较小;2)对于理想弹塑性或剪胀性不明显的岩体,采用内部支护对维持岩体稳定性非常有利,既可减小岩体的应力释放,又可增大围岩变形控制效果。

尤建良运用“隧道逆癌疗法”治疗大肠癌肝转移的经验

尤建良教授在长期诊治晚期肿瘤的实践中积累了丰富的临床经验,提出隧道逆癌疗法治疗大肠癌肝转移。其理论核心就是:通过探寻隧道的入口,结合辨病辨证,施药以改变隧道中的土壤,使得土壤不适宜肿瘤生长,然后再不断地辨证,不断地减轻症状,逐步改善肿瘤生长的微环境和患者的微症状,最终达到抑制、甚至逆转肿瘤生长的目的。

含粘合剂的摩擦电接触材料性能研究

以聚硫橡胶改性环氧树脂作为粘合剂,石墨/焦炭为基体,考察了组分含量不同时材料的摩擦磨损性能和导电性能的变化规律。揭示了组分含量对摩擦磨损性能的影响,并用隧道理论较好地解释了高粘合剂含量时材料的非线性电行为。

掺杂浓度对多晶硅纳米薄膜应变系数及其线性度的影响

利用低压化学气相沉积（LPCVD）技术制备了不同掺杂浓度的多晶硅纳米薄膜，并对样品的压阻特性进行了测试．采用最小二乘法对实验数据进行拟合，得到了应变系数及其线性度与掺杂浓度的关系．实验结果表明：掺杂浓度从8．1×10^18cm^-3变化至7．1×10^20cm^-3，多晶硅纳米薄膜的纵向和横向应变系数先增加再减小，最后基本不再随掺杂浓度而变化，且纵向应变系数大于横向应变系数：掺杂浓度低于4.1×10^19cm^-3时，应变系数的非线性较大，且随掺杂浓度的升高而迅速减小；掺杂浓度高于4．1×10^19cm^-3时，应变系数的非线性较小并出现波动现象，同时纵向应变系数的非线性小于横向应变系数的非线性．利用隧道压阻理论对实验结果进行了分析．结合以前的研究结果可知，适合传感器制作的多晶硅纳米薄膜的优化掺杂浓度应为（2．0～4．1）×10^20cm^-3，为进一步利用多晶硅纳米薄膜制作传感器提供了非常有价值的参考信息．

Frequency responses of immersing tunnel element under wave actions

The immersion of large-scale tunnel elements is one of the most important working procedures in the construction of an underwater immersed tunnel. To investigate the dynamic characteristics of tunnel element in the process of immersion, based on the twin-barge immersing operation method, the frequency-domain analysis of the tunnel element motions under wave actions was made. The linear wave diffraction theory and the three-dimensional source distribution method were applied to calculate the wave loads and motion responses of the tunnel element under different incident wave conditions. In the study, movement of the two barges in the water was assumed to be small and was ignored. Cable tension was computed by the static method. On the basis of the above theories, a computer program was made, and two cases were taken to check the validity of the program. The results showed that wave loads acting on the immersed tunnel element are relatively large near the water surface, and they decrease with the increase of immersing depth of the tunnel element. Wave loads first increase, then decrease, with the increase of wave period. The motion responses of the tunnel element are also generally large near the water surface and decrease as the immersing depth increases.

外加电压对沥青碳纤维/ABS树脂复合材料导电性的影响

通用级沥青碳纤维与 ABS树脂通过单螺杆挤出机共混后模压成型 ,所制复合材料的电阻率随材料中纤维添加量的增多而迅速降低。当复合材料中纤维添加量较少时 ,材料的电流电压关系不满足欧姆定律所描述的线性关系 ,材料电阻随外电压的增大而减小。随着纤维含量的增加 ,材料电流电压关系的线性度逐渐增大。当纤维含量达到 40 wt%时 ,材料电阻不随外电压的增大而变化 ,材料满足欧姆定律。经外加高电压处理后 ,材料电阻率发生永久性降低 ,其电流电压关系的线性度提高。

园偏振光场电离电子的剩余能量

以准静态隧道电离理论为基础 ,推导了园偏振光场电离多电子原子体系的剩余电子能量的计算公式 ,得出一个有趣的结论 ,在超短脉冲园偏振光场的作用下 ,平均剩余电子能量只与电离速率和脉冲包络有关。数值模拟表明 。

多晶硅应变因子计算研究

伴随多晶硅力敏电阻在高温压力传感器和微机械传感器上的应用,学者对其压阻效应原理进行深入研究。本文论述了P型多晶硅隧道压阻模型和应变因子理论计算存在问题,提出了一种应变因子改进算法,与实验结果比较表明该算法的科学性,为多晶硅广泛应用打下一定的理论基础。

面向调线调坡的点云大数据分析及深度模型研究

已建成的隧道与原始的设计隧道之间的偏差信息对于地铁线路的安全调整非常重要。然而,目前还没有明确的数学公式能够准确地描述和度量这个偏差。目前主流的做法是通过人工测量具有相同间隔的截面的侵限值,并对这些侵限值进行累加求和,最终得到该偏差,这种方式存在误差大、耗时、成本高等缺点。为了解决这些问题,提出了一种新的基于深度神经网络的偏差表示方法,其能够基于点云大数据学习到设计线路的参数与侵限值之间的内在联系,进而预测出能够使得侵限值的和最小的参数,这些参数可以被用来辅助地铁线路的安全调整。在一个采集于实际地铁工程中的数据集上的实验结果表明,该方法能快速地计算出合适的调线调坡方案,并且只需要很少的计算机内存资源。

Analytical solution of a circular lined tunnel with alterable mechanical property under hydrostatic stress and internal pressure

The influence of the interaction between surrounding rock and lining on the long-term behaviour of a tunnel in service is significant.In this paper,we proposed a mechanical model of the circular lined tunnel with the alterable mechanical property under hydrostatic stress and radially inner surface pressure of the lining.The alterable mechanical properties of the surrounding rock and the lining are embodied by the changing of their elasticity modulus with service time and radial direction of the tunnel,respectively.The proposed mechanical model is successfully validated by comparison with the existing theoretical models and the numerical simulation,respectively.The influences of the main parameters of the proposed mechanical model,such as the radial power-law indexes and the time-varying coefficients of the surrounding rock and the lining,as well as the radially inner surface pressure of the lining,on the interface displacement and pressure between surrounding rock and lining are investigated.The research results can provide some valuable references for timely diagnosis and correct evaluation of the long-term behaviours of a tunnel in service.

First-principles Study on Geometric and Electronic Structures of Si（111）-√7× √3-In Surface Reconstruction

In order to determine the structures of Si（111）-√7 √3-In surfaces and to understand their electronic properties, we construct six models of both hexagonal and rectangular types and perform first-principles calculations. Their scanning tunneling microscopic images and work functions are simulated and compared with experimental results. In this way, the hex-H3＇ and rect-T1 models are identified as the experimental configurations for the hexagonal and rectangular types, respectively. The structural evolution mechanism of the In/Si（lll） surface with indium coverage around 1.0 monolayer is discussed. The 4×1 and -√7× √3 phases are suggested to have two different types of evolution mechanisms, consistent with experimental results.

Stability analysis of shallow tunnels subjected to seepage with strength reduction theory

Based on strength reduction theory,the stability numbers of shallow tunnels were investigated within the framework of upper and lower bound theorems of limit analysis. Stability solutions taking into account of water seepage were presented and compared with those without considering seepage. The comparisons indicate that the maximum difference does not exceed 3.7%,which proves the present method credible. The results show that stability numbers of shallow tunnels considering seepage are much less than those without considering seepage,and that the difference of stability numbers between considering seepage and without considering seepage increase with increasing the depth ratio. The stability numbers decrease with increasing permeability coefficient and groundwater depth. Seepage has significant effects on the stability numbers of shallow tunnels.

Use of fuzzy set theory for minimizing overbreak in underground blasting operations——A case study of Alborz Tunnel,Iran

In order to increase the safety of working environment and decrease the unwanted costs related to overbreak in tunnel excavation projects, it is necessary to minimize overbreak percentage. Thus, based on regression analysis and fuzzy inference system, this paper tries to develop predictive models to estimate overbreak caused by blasting at the Alborz Tunnel. To develop the models, 202 datasets were utilized, out of which 182 were used for constructing the models. To validate and compare the obtained results,determination coefficient(R2) and root mean square error(RMSE) indexes were chosen. For the fuzzy model, R2 and RMSE are equal to 0.96 and 0.55 respectively, whereas for regression model, they are 0.41 and 1.75 respectively, proving that the fuzzy predictor performs, significantly, better than the statistical method. Using the developed fuzzy model, the percentage of overbreak was minimized in the Alborz Tunnel.

Drivers'fixation transfer characteristics in urban tunnels

To improve the safety performance of urban tunnels,the fixation transfer characteristics of drivers with different driving experience levels in urban tunnels were investigated.First,a real vehicle test was performed in an urban tunnel,and the eye movement data of 10 drivers with different driving experience levels were collected using a Dikablis eye-tracking system.Second,the driver fixation range was divided into eight areas of visual interest by using the K-means clustering method,and the fixations in different sections of the tunnel were comparatively analyzed.Finally,on the basis of the divided areas of visual interest,fixation transfer rules and the stationary distribution characteristics of drivers with different driving experience levels on different sections of the tunnel were discussed using Markov theory.Results indicate that drivers'probability of repeated fixation is greater and that the efficiency of visual search is lower at internal sections of tunnels than in external sections.Drivers obtain information mainly from the straight upper front and straight lower front areas,and the probabilities of fixation points in these two areas at the threshold and exit sections are significantly higher than those in other sections.Relative to experienced drivers,novice drivers allocate little attention to the straight upper front area and rear-view mirrors.Hence,they have weak fixation when looking forward,and they lack experience in obtaining information on rear-approaching vehicles and controlling speed.

激光物理

TN241 2000020894圆偏振光场电离电子能量分布的计算=Electron energydistribution in circularly polarized optical-field ionized plasmas[刊,中]/陈德应,卢兴发,夏元钦,张彬彬,王骐(哈尔滨工业大学光电子技术研究所.黑龙江,哈尔滨(150001))//光学学报.-1999,19(7).-884-888以准静态隧道电离理论为基础,建立了描述圆偏振光场电离电子能量分布的简单模型。与现有的理论计算及实验结果的比较表明,该模型数学推导简单、物理意义明显,可用于研究较高电子温度和(或)较低电子密度的光场电离等离子体参数。图3参19(严寒)

合谋理论研究述评

公司治理是目前经济学和财务学最受关注的研究领域之一。早期的研究主要集中在因为股权高度分散而导致的管理层与外部股东之间的代理问题，比如Berle和Means（1932）的开创性研究以及Jensen和Meckling（1976）的研究等等，这为“第一类代理问题”——管理层如何保护不是所有者的股东的利益，而是怎么去为自己谋福利——建立了坚实的基础。

融资约束、控制权私利与金字塔结构——来自中国中小民营上市公司的经验证据

利用中国中小民营上市公司的数据实证检验了公司金字塔结构产生的原因,研究发现,边际获利能力越低的公司越可能被金字塔结构控制,被金字塔结构控制的公司更可能雇佣高质量的会计师事务所,向外部投资者发送不掠夺的信号。国家的税收和其他政策对公司组织结构的选择具有重要影响,税负越低的公司越可能被金字塔结构控制,股权分置改革后终极控制人较少利用金字塔结构控制上市公司。