季节性冻土地区牵引变电所接地方案研究

在季节性冻土地区,地面冻土层的土壤电阻率随季节性因素变化很大,将严重影响接地网的安全性能,此时采用参数合适的复合接地网将比水平接地网具有更好的降阻效果及安全性能。以哈牡铁路亚沟牵引变电所为例,采用CDEGS软件进行仿真计算的方法,分析在季节性冻土地区影响接地网安全性能的四个因素(水平均压带网格大小;垂直接地极数量、长度及位置),得出采用水平均压带与垂直接地极相结合的复合接地网方案为工程最佳方案。     

对高土壤电阻率地区牵引变电所接地技术的分析

从接地的实质出发,论述短路电流是接地电阻的控制因素。从土壤湿度、土壤温度、土壤结构类型等3个方面分析土壤电阻率对接地电阻的影响,提出高土壤电阻率地区变电所降阻措施,以及接地网设计的一些方法。     

油罐荷载作用下的饱和黄土地基沉降试验研究

文章结合兰州原油末站（罐区）地基处理工程实例,采用土工离心模型试验对油罐荷载作用下的黄土地基进行模拟分析,总结出油罐荷载作用下饱和黄土地基的沉降机理与承载行为,为油罐荷载作用下饱和黄土地基的沉降及控制研究提供参考。     

粘性土中轴向受力桩的解

本文根据14根现场灌注桩(直径。.6~1.4m,入土深度16.7一42m) 轴向待载试验结果的分析,提出了拈性土地基中桩侧摩阻力与桩端阻力 随其位移发挥的非线性理论模式。一:曲线、q一s,曲线),并考虑理 深、施工方法和土的性质的影响,由常规土工试验结果推求出模式的控 制参数。用截面状态矢量法求解两根试桩所得结果同实测值对比,墓本 上是吻合的。因此,可以根据桩顶荷载一沉降曲线(P一:曲线)比较 合理地确定桩的轴向刚度和极限荷载。      

沉埋式双排抗滑桩加固滑坡承载机理研究

为探究沉埋式双排抗滑桩(沉埋式后排桩和全长式前排桩的组合形式)的承载机理,采用土压力盒和应变片完成一系列室内模型试验,在外界施加的滑坡推力作用下,量测桩身内力变化与桩周土体压力的变化情况,研究桩身受力的分布形式和土拱效应,并分析后排桩长度变化时的双排桩的受力变化规律。研究结果表明,沉埋式双排抗滑桩的受力方式不同于全长双排抗滑桩的受力方式:沉埋式抗滑桩前排桩桩后推力分布形式为梯形分布,桩前抗力分布形式为矩形分布;后排桩桩后推力分布形式呈梯形分布,桩前抗力分布形式为倒梯形分布。后排桩的沉埋深度对前排桩的土拱效应有着较大的影响,并且分析认为当前后排桩承载比较接近时的沉埋深度为设计沉埋深度。为进一步探究排距对沉埋深度的影响,运用FLAC3D,探讨不同排距下双排桩的承载比。研究结果表明,随着排间距增大,后排桩的设计沉埋深度逐渐减小。     

A method to predict the torsional resistance of suction caisson with anti-rotation fins in clay

Suction caisson foundations have been increasingly employed as a primary solution to support the offshore fixed- or mobile-structures. Due to harsh environment and complex force transferring of offshore structures, they are still being developed as to satisfy increasing requirements in strict working scenarios. One of emerging challenges is a torsion-governing failure, which has been observed in the oil and gas industry (i.e. significant multiple-inline-force-induced torsion) and in the renewable energy field (i.e. non-coplanar tensile force induced torsion). This paper introduces a novel suction caisson foundation, with anti-rotational fins assembled on the outer skin of caisson. By a comprehensive numerical study, the evolution from local to global failure as the fin numbers from single to multiple, is examined in the clayey soil deposit with effects of soil strength heterogeneity, fins dimension, installation process and foundation-soil interface considered. Based on these, a set of methods to estimate the ultimate torsional capacity of such novel caisson is proposed, which starts from the gain in capacity for a single fin, and evaluate the changes of gains in capacity as fin numbers, then identify the optimised anti-rotational capacity. Finally, three key parameters (i.e. the required fin numbers, the available anti-rotational capacity and the optimised anti-rotational capacity) with some critical considerations, recommendations and implications have been concluded for design practice.     

长江隧道施工对周围建筑的影响研究

研究目的：在城市中心城区建造隧道，对周围建筑物的影响是个不容忽视的问题，对其进行研究，进而采取有效的措施加以保护，是工程施工顺利进行的有力保证。研究方法：采用数值模拟方法，利用大型有限元软件，通过合理的简化分析和假定建立数值分析模型，分析武汉长江隧道施工对周围历史建筑影响最大的对象——鲁兹故居的影响。研究结论：差异沉降是鲁兹故居应力分布及应力最大值的主要影响因素，差异沉降值的大小对应力分布及应力最大值的大小影响显著，工程中要严格控制地表差异沉降，尽量减小差异沉降值的大小。     

Monitoring of suction bucket jackets for offshore wind turbines: Dynamic load bearing behaviour and modelling

Suction bucket foundations for offshore wind turbines (OWT) have considerable advantages compared to conventional foundation types: Due to the installation process with dead weight and applied negative pressure, noise from pile driving can be completely avoided. In addition, the installation process of the whole substructure, consisting of the buckets connected to the jacket, can be carried out in one work step, which increases efficiency. A prototype of the suction bucket jacket was installed in the wind park ‘Borkum Riffgrund 1’ (North Sea) in August 2014. Due to the pre-installed and comprehensive measuring system, it was possible to monitor all installation and operating phases. The data analysis of a storm event show an amplitude and frequency-dependent behaviour of the soil stiffness and the suction bucket foundation without wind turbine. In the frequency range of the first and second eigenfrequency (0.2 Hz < f < 5 Hz), the system behaves linearly. Here, the Frequency Domain Decomposition is used for identification and monitoring. For the lower frequency band (0.05 Hz < f < 0.2 Hz) where higher forces and displacements occur, a non-linear multilayer perceptron is chosen to model the non-linear relations between measurements. By applying two mathematical models for the relevant frequency ranges, all the information from the measurement data can be used for system identification and novelty detection under varying environmental conditions.     

The change in soil cover on the exposed bed of the Aral Sea

Desiccation of the Aral Sea has led to the formation of new soil cover on the exposed seabed. Investigation of the newly formed dry land is very important since it is a source of dust storms and salts transferred to long distances. A soil map of the exposed seabed for 2000 has been produced on the basis of the map for the year 1990 (Institute of Soil Science, Uzbekistan), satellite images, and selected field observations of groundwater table. During the period 1990–2000, the sea recessed 20–32 km, thus changing the soil cover characteristics. The maps of soil cover with the detailed information on soil textures, the characterization of soil types, the soil formation trends, and the changes in soil types during the sea recession process are available. Attention has been paid to erosion tendencies and susceptibility to dust and salt transfers. As a whole, the soil cover was formed as a result of the replacement of excessive wetlands (salt-marsh), located in the form of strip along the sea, by hydromorphic and semi-hydromorphic, semi-automorphic and automorphic soils. The drying seabed has complicated lithological and morphologic composition. The territory of the exposed seabed is characterized by different hydrological conditions. Groundwater depth varies from 0.5 to 10 m. With the shore's recession, the water storage groundwater is approaching the surface. With general tendency towards desertification, the initial soil cover changes. The soils that did not reach the complete genetic formation, under the influence of quickly changing hydrogeological conditions, are transformed into the other types and subtypes. Often, while becoming dry, they are self-destructed and change into sands. Currently, the following types of soils are observed on the exposed seabed: automorphic solonchaks, semi-automorphic solonchaks, semi-hydromorphic solonchaks, hydromorphic solonchaks, desert sandy soils, sands.     

普氏理论在确定抗滑桩间距中的应用

从方桩桩间土拱形成的机理、力学特性入手,将广泛应用于隧道工程的普氏系数引入抗滑桩最大间距的计算分析中,并根据桩间土拱的静力平衡,建立了相应的计算模型。同时以泸州市世寿街滑坡为例,对所推导的最大桩间距计算公式进行验证,计算结果为1 75m,与实际工程设计基本一致。