软硬互层岩滑坡的变形特征及稳定性分析 ——以湖南郴州S215公路K3+172~K3+252段滑坡为例

在软硬互层岩石中,地质灾害极易发生。本文以S215公路K3+172~K3+252段滑坡为研究对象,分析了该滑坡的空间形态、物质组成和变形特征,采用极限平衡法,选择折线型滑动模型,在两种不同工况下对其稳定性进行了计算,最后对滑坡稳定性进行了评价。滑坡在天然工况I条件下为基本稳定状态,在暴雨工况Ⅱ条件下为不稳定状态。提出了多级抗滑桩工程、截排水工程、坡腰平台复绿工程、道路路面修复工程和监测工程相结合的综合防治工程,为该滑坡的后期治理提供了依据。     

可靠性增长数据突变点的辨识方法

对可靠性增长数据的突变点,本文提出了一种客观而精确的辨识方法。该法是基于Ｃｒａｍｅｒ－ＶｏｎＭｉｓｅｓ拟合优度检验统计量上的最优化技术。     

变截面超静定梁的传递矩阵解法

采用矩阵传递法分析了变截面超静定梁的弯曲问题。利用截面状态矢量的传递规律,求解任一截面的内力和变形。与其它方法比较,该方法提供的是程式化的数学模型,便于计算机分析。     

开口薄壁杆的非线性动力稳定性分析

基于弹性薄壁杆的经典理论考虑到拉压,弯曲及扭转的耦合效应,建立了开口薄壁杆的非线性运动控制方程组,应用谐波平衡法。     

对一个Petri网进程表达式的探讨

Petri网进程是Petri网分析和验证的有效手段,而Petri网的进程表达式可以给出系统全部进程的描述。针对文献《一种基于同步合成构造Petri网进程表达式的方法》提出的基于同步合成的Petri网表达式构成方法中的一个引理进行深入研究,并通过一个反例,说明这种方法的错误之处。     

浅埋大采高工作面区段煤柱下合理留设宽度模拟研究

本文利用FLAC3D数值模拟软件通过建立模型对不同宽度煤柱下巷道围岩垂直应力、变形及破坏规律进行了研究分析。研究认为:随着煤柱宽度的增大,煤柱应力集中范围越来越小,应力集中系数越来越小,逐渐呈现均匀承载现象,同时巷道围岩位移量、煤柱塑性区、巷道围岩塑性区范围也逐渐减小。随着煤柱宽度的增大,煤柱弹性区域范围越大,煤柱越稳定,回采巷道越安全,考虑到煤柱过宽会造成资源的浪费,最终确定合理的区段煤柱尺寸在14~16 m之间。     

高速铁路10 kV电力贯通线故障区段定位方法

提出了一种基于区段两端零模电流值乘积积分的高速铁路电力贯通线故障定位方法.该方法借助现有铁路远动系统,仅需要每个区段终端FTU上的零序电流值,即可快速准确定位故障区段.数字仿真试验结果表明:该方法不受故障距离、配变负载及过渡电阻的影响,且对FTU数据采集的采样率和同步性有良好的适应性.     

茴香成熟叶柄石蜡切片技术的研究

石蜡切片技术是一项基础的实验技术,在具体操作过程中仍经常在的裂纹、皱缩、不粘片、脱落、薄厚不匀等问题.且不同作物,同一种作物不同器官,同一器官不同发育阶段,每一环节所采取的方法不同,在实际操作工程中均不能照搬实验指导或者文献,而需要进行反复摸索才可以制得一个理想的片子.实验以小茴香成熟叶柄为材料,通过大量的摸索性试验,成功制得了小茴香成熟叶柄的永久性石蜡片子,明确了叶柄的内部组织构造,提出了取材与固定、脱水与透明、浸蜡与包埋、染色、切片、粘片等关键环节的适宜操作方法,提高了制片效率和成功率,为利用石蜡切片技术进行科研和教学的工作人员提供参考.     

涡流发生器对3/4汽车模型风洞流场品质的影响

采用数值计算的方法对3/4开口回流式汽车风洞喷口处的涡流发生器进行了研究.对比研究了三种不同片数的涡流发生器对流场品质的影响.首先采用定常雷诺时均纳维斯托克斯方程求解了流场的定常特性,接着采用大涡模拟(LES)方法对流场的非定常特性进行了研究.并就两种计算方法给予了相应的试验验证.对比计算结果得到涡流发生器可以在一定程度上提高流场均与性,尤其是三片式涡流发生器的工况能较好地拓宽风洞测试区的高流速区域的范围,降低测试区的静压梯度,减小试验段内的湍流度和剪切层内的湍流度,延长测试段内低湍流区的长度,分散流场内的脉动能量,降低低频颤振敏感频率区的能量聚集.     

Redox condition during Ediacaran–Cambrian transition in the Lower Yangtze deep water basin,South China: constraints from iron speciation and δ~(13) Corg in the Diben section,Zhejiang

Cherts of the Piyuancun Formation and black mudstones of the Hetang Formation in Diben Town, Kaihua County, Zhejiang were deposited in a deep water basin of the Lower Yangtze area during the Ediacaran–Cambrian transition(E–C transition), offering an opportunity to reconstruct the ancient redox condition of the deep water basin. Total 53 samples were collected and analyzed for iron speciation, including pyrite iron(FePy), carbonate associated iron(FeCarb), iron oxide and hydroxide(FeOx),magnetite iron(FeMag) and total iron(FeT) as well as d13 Corgto gain a deeper understanding of specific redox condition during the period. The results show that(1) most samples have pyrite concentration \1 %, with the FePy/FeHR ratio ranging from \0.01 to 0.81(mostly \0.5), and the FeHR/FeT ratio between 0.39 and 0.93(mostly [0.5).(2) The E–C boundary in the Diben section occurred at the maximum negative excursion of organic carbon isotope within the Piyuancun Formation, which can be correlated with other sections by using d13 Corg. We thus concluded that the relatively high content of highly reactive iron and low content of pyrite iron in the Diben section indicate a minor occurrence of H2 S and a predominance of anoxic and ferruginous environment, which is similar to other reported sections such as the Longbizui and Yanwutan sections, western Hunan. In addition, oxygen concentration in sea water showed an increasing trend in the interval corresponding to the bottom and upper layer of the Hetang Formation as indicated by the FeHR/FeT ratio, which decreased from 0.7 to 0.38, however, it was not great enough to oxidize the whole deep water. Therefore, during the E–C transition deep water basin in South China was most likely an anoxic and ferruginous enrironment, which prevented metazoon from the evolution in the deep water basin. Our work offers an important reference to better understanding of the spatiotemporal occurrence and dynamic processes of the ‘‘Cambrian Explosion'.