钢筋混凝土结构施工期间可靠度的分析方法

施工期间对结构的安全性和可靠性有着严格的要求．由于施工过程中，结构是一个时变结构，结构的抗力是一个随机过程，荷载也具有与使用期不同的特点，所以有必要研究施工期间结构的可靠度．在已有的钢筋混凝土结构现场施工活荷载统计资料的基础上，考虑了抗力在施工期间随时间增长的特性，研究了结构的可靠度，分析了算例．结果表明：本方法切实可行，对施工期间的安全管理有一定的指导意义．     

复杂地基的人工挖孔桩成孔施工技术

本文就人工挖孔灌注桩在复杂地基条件下的排水施工方法，穿越流砂、淤泥质土层，岩层和岩溶地基的人工成孔施工技术作了有益的探讨．     

小康井田煤系地质构造

应用构造地质学原理和方法,阐述了小康井田3组褶皱、5组断层的发育特征和分布规律;从区域构造背景、构造应力场演化揭示了该井田地质构造的形成期次,即先后形成了压性结构面(以褶皱轴面、逆断层面为代表)走向呈北西西、北东东、北北西向的构造系统;分析了后期构造形迹迁就和改造先存构造形迹的力学性质转化,其中,由于断层多期活动的综合效应和构造抬升、应力松弛使绝大部分断层现今表现为正断层;指出走向为北北东向同沉积正断层对原始煤层的发育具有控制作用,其他方向的断层尤其是北北西向或近南北向的断层,主要表现为成煤后对煤层的破坏作用.     

大体积混凝土结构裂缝成因及预防措施

许多建筑物的结构,特别是有大体积混凝土的建筑物,在建设过程和使用过程中出现了不同程度、不同形式的裂缝。探讨了大体积混凝土结构裂缝的发展规律、成因及危害,提出了综合防治措施。     

基于RBF神经网络的结构可靠度分析方法

蒙特卡罗模拟是目前结构可靠度分析中最准确有效的方法,但因其计算量太大、效率低而受到很大的限制,特别是对于大型复杂结构的功能函数不能被明确表达的情况.鉴于此,在蒙特卡罗重要抽样方法的基础上,提出了利用RBF神经网络替代原结构功能函数的RBF-蒙特卡罗方法,以提高工作效率.RBF神经网络训练样本的选取则由均匀试验设计确定,以提高样本的代表性并大幅减少样本数量,从而加快网络的训练过程,加强网络的逼近能力.算例分析表明,该方法不但能最大限度地减少结构有限元分析次数,而且有满意的计算精度,具有实际应用价值.     

不同导叶包角圆管螺旋流起旋器出口流速场的试验研究

探讨了产生圆管螺旋流的局部起旋器,并在模型试验的基础上,通过对两套起旋装置在不同流量下的轴向流速及周向流速以及起旋器结构参数的比较和分析,得到了更有利于圆管螺旋流输送的结构参数。     

浅谈桥梁结构模型竞赛对桥梁工程教学的促进

桥梁工程是土木工程专业的核心课程,但是在目前桥梁工程课程的教学中,存在实践教学环节弱化的问题.本文针对这一问题,结合本人的体会,指出当前一些高校举办的桥梁结构模型竞赛活动对桥梁工程课程的教学有较好的促进作用,可以作为桥梁工程教学中一种开放的实践环节.     

The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

Rising atmospheric CO2 and temperature are altering ecosystem carbon cycling. Grasslands play an important role in regional climate change and global carbon cycle. Below-ground processes play a key role in the grassland carbon cycle because they regulate …     

Temporal-spatial dynamics of distribution patterns of microorganism relating to biological soil crusts in the Gurbantunggut Desert

Biological soil crusts serve as an important biological factor contributing to the sand fixation. This study was conducted to investigate the temporal-spatial variability of microorganism in crusts relating to locations, soil layers of sand dunes and seasons. At moss-dominated inter-dune areas, higher soil nutrient and water concentrations were likely to maintain the microbial activities. Bacteria showed the highest capabilities of settlement and growth in inter-dunes in both spring and autumn. Soil water content reached the highest value in soil crusts in the inter-dune areas, especially in spring. Variations of quantities of actinomyces and fungi basically showed the consistent trend in different locations of sand dunes. With the deepening of soil layers, vertical distribution of quantities of each microorganism group showed different characteristics because environmental factors fluctuated in both spring and autumn. Among different microorganism groups, bacteria were predominant, actinomyces the next and fungi the least in both spring and autumn in all soil layers （0-20 cm）. The proportion of bacteria and soil water content were higher in spring than those in autumn in all soil layers （0-20 cm）. No consistent trends were found in actinomyces and fungi. The results showed that the quantities of microorganisms were significantly positive correlated with organic matter content, soil water content, total N, total P, available P, available K, pH, electrical conductivity, total salt content,catalase, urease, phosphatase and alkaline phosphatase.