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61.
基于不同水压分布的平面滑动边坡稳定性研究 总被引:2,自引:0,他引:2
为研究地下水对平面滑动边坡的影响,归纳了平面滑动边坡常见的3种水压分布形式,并阐述了其分布假设的合理性。根据极限平衡理论,采用Matlab编制程序,通过有无张裂缝两个算例,定性与定量分析相结合,就不同滑动面水深、滑动面倾角、坡高、坡顶倾角、裂缝水平夹角等影响因子进行敏感性分析,重点探讨了在不同水压分布时影响因子对边坡安全系数影响的动态演绎规律。研究表明,平面滑动边坡临界倾角可通过极限平衡理论编制程序计算,并考虑地下水得出临界倾角变化趋势,取经验值10%为浮动范围;边坡影响因子对安全系数的影响随着地下水位的升高而变大,其中坡高对安全系数影响显著,坡顶倾角、张裂缝水平夹角和坡顶距张裂缝距离等对安全系数影响不明显。 相似文献
62.
pH平面光极在生物扰动存在下水/沉积物体系中的应用 总被引:2,自引:0,他引:2
为了解生物扰动存在下水/沉积物体系中pH的分布和变化特征,通过改进传感膜制备方法和图像采集与定量方法,建立了基于平面光极的pH二维分布实时监测系统,并应用于生物扰动存在下淡水/沉积物模拟体系pH时空分布规律的监测。结果表明:与已有方法相比,本方法具有响应pH范围宽(6.2~8.6)、响应快速(响应时间<30 s)、准确性高、可逆性和抗干扰性强、稳定性好等优点,可用于监测有扰动生物存在的水/沉积物模拟体系微环境的pH,直观反映pH的时空变化规律。对模拟体系的监测结果表明:沉积物自身pH时空变化虽较小,但其对上覆水pH有重要影响,上覆水pH存在显著而复杂的变化。体系pH的变化规律是多种机制作用的结果,而生物扰动对这些作用均有影响。 相似文献
63.
针对现有大规模点云数据平面特征分割方法中存在的错误识别、效率低、抗噪性差等问题,该文提出一种基于2D霍夫变换和八叉树的建筑物平面精细分割方法。该方法首先,对原始点云进行空间均匀降采样并向X-Y面投影,利用改进的2D霍夫变换算法提取投影后的点云线段,使用选权迭代法精确计算线段所在直线的方程及端点坐标,进一步确定立面的空间几何方程;接下来,建立原始点云数据的八叉树结构,利用端点坐标设计立方体并分割出立方体内的立面点云;最后,将立面点云从原始点云中剔除,对余下点云降采样并向X-Z面投影,重复以上过程分割水平面点云。试验验证了该文方法对建筑物面状特征分割的有效性。 相似文献
64.
?????????????????????????????б????????????????????????????????????????????????????????????????С????????????????????Ч???????????????????????????????????????????????????????????????????????÷????????У???????????????????????????ο??? 相似文献
65.
In gravel‐bed rivers, the microtopography of the bed is known to exert a significant influence on the generation of turbulent flow structures that owe their origin to fluid shear generated near the bed. Although field and laboratory measurements have indicated that flows over gravel beds contain a range of coherent flow structures, the kinematic and dynamic properties of these structures are still poorly understood. This paper describes a new experimental methodology to quantify simultaneously both the kinematic and dynamic characteristics of coherent flow structures based upon combined planar laser‐induced fluorescence and particle imaging velocimetry (PLIF‐PIV). The results confirm that the primary generative mechanism of coherent flow structures is at the bed, where merging hairpin vortices form around bed clasts and generate larger‐scale fluid motions that advect downstream. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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在地籍测量中我们常用的坐标系是西安80坐标系和一些地方坐标系,且多数情况下用的是平面坐标系(一般,高程需单独处理)。另外,地籍测量一般作业区域不大,可将其视为平面。坐标系转换问题可简化为平面坐标系之间的转换,其转换一般用的是四参数模型。本文详细推导了建立简化的坐标转换四参数模型的过程,再运用最小二乘平差原理求出四参数的精确解,然后对其进行精度评定,最后给出算例验证了模型在满足精度的前提下,具有广泛的实用性。 相似文献
69.
???????????????????????????????÷?????????DLT????????????Huber????????????λ??????????????????????????????????????????????????????????????????????????????λ??????????????????????????и???????????????? 相似文献
70.
Goat Paddock in northern Western Australia is a ~5 km-diameter impact crater of Eocene age excavated in gently dipping Proterozoic sandstones. Roughly radial gorges formed by post-impact erosion provide cross-sectional views of the wall and rim zone. The predominant structural theme is one of synclinal rim folding with broad zones in which bedrock strata were deformed by impact to steep, vertical and overturned attitudes. Impact breccia is found craterward of deformed bedrock, on top of it, and downdropped into fault troughs roughly concentric to the crater. The bedrock?–?breccia contact is sharp in some places and gradational in others. In at least one section, the entire mass of upturned bedrock and breccia was displaced radially over essentially undisturbed bedrock, as indicated by slickensides on the horizontal contact. Talus deposits are similar to breccia, but show rough size sorting and clast orientation that dips steeply craterward, indicating that the talus formed as slides down the oversteepened crater wall immediately after crater formation. Shatter cones in some clasts indicate that allogenic material is incorporated in these deposits. Suevite, characterised by ropy flow textures, and by microclasts of quartz with planar deformation features, planar fractures, and of vesiculated silica glass, was found overlying deformed bedrock at a point where the surface of the bedrock forms a nearly horizontal bench midway up the crater wall. The crater was at least partially filled by later sediments, represented by bedded conglomerate close to the crater wall grading inward to sand, silt and mudstone recovered by drillholes on the crater floor. Some of the talus and conglomerate occupy re-entrants in the crater walls, suggesting an original scalloped outline to the crater. Two drillholes, one central and one halfway to the wall, both reached brecciated sandstone after penetrating 210 m of lake sediments. Goat Paddock has a flat floor with no indication of a central uplift and a depth/diameter ratio of ~0.073. This crater form, coupled with the modification of the crater walls by slumping and the scalloped outline of the crater rim suggests that Goat Paddock bridges the two traditional classes of impact crater: simple and complex. 相似文献