共查询到19条相似文献,搜索用时 191 毫秒
1.
2.
3.
4.
5.
6.
通过对某煤矿区域断层位置及断层破碎带的含水性实例分析,介绍了可控源音频大地电磁法(CSAMT),时域激电(TDIP)这两种方法的实际应用,实践证明这两种方法联合应用在探测断层位置及断层破碎带的含水性能方面取得了较好效果。 相似文献
7.
叙述了地质勘查中的大功率激电方法,以及在青海某煤炭勘查项目中的应用,指出此方法不仅可以获得电阻率还可获得极化率等参数,且勘探深度较大,利用实际勘查数据,给出了激电测深剖面ρs,ηs曲线。 相似文献
8.
9.
以湖南某生活垃圾卫生填埋场为例,分析充电法、激电法和高密度电法相结合的方法在寻找渗漏径流通道中的可行性和应用性,近期发现该垃圾场下游50 m处的水井有严重污染迹象,且已对地下水系统造成污染,因此对填埋场及周边进行地球物理探测,旨在查明渗漏径流通道的走向、位置及深度等。针对上述目的,采用充电法圈定异常8处,高密度结合激电测深法圈定异常1处。在圈定的异常处进行钻探,伴有大量污水污泥涌出,且抽水试验点上游的水位发生急剧变化,涌水量100 m3/d时,降深13.4 m,证实了三者结合在查找渗漏径流通道及污染趋势方面,具有良好的勘探应用前景。 相似文献
10.
11.
One of the challenges confronting structural engineers in structural control is to find more efficient control algorithms to ensure better and more reliable control results to protect structures against the damaging effects of destructive environmental forces. In this paper, a simple control algorithm, namely the Predictive Instantaneous Optimal Control (PIOC) algorithm, is proposed by introducing a new state space form. Different from the classical ground acceleration‐based control algorithms, this new control algorithm uses earthquake ground velocity as the input. Since the earthquake ground velocity is not at high frequency as compared with the ground acceleration, it can be predicted at certain time steps beforehand in real‐time domain with higher accuracy. This ensures the synchronous execution of the proposed PIOC algorithm with real‐time application of the control force. To capture the damaging effects during earthquake ground motions, the force analogy method is used to characterize structures responding in the inelastic domain. Numerical studies are performed to compare the structural response with and without control using both single degree of freedom and multi‐degree of freedom structural models. Results show that the PIOC algorithm is effective in reducing the structural response under earthquake excitation. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
12.
针对盾构法施工时开挖仓封闭,地质预报实施难的问题,设计一种基于聚焦电流法和频域激电法的超前地质预报方法,可实现低功率下探测电流的发射和有效接收.为了提高测量精度和稳定性,引入电流测量线圈实现探测电流的有效聚焦,解决了聚焦电流法中易产生的欠聚焦和过聚焦问题.本文介绍了聚焦电法和频域激电法的原理以及二者结合后的优势,建立了... 相似文献
13.
针对深部难钻地层钻头的钻速低、寿命短、能耗高等问题,在常规固定齿PDC钻头上引入旋转模块结构,旋转模块齿和固定切削齿“交叉刮切”破碎岩石,提高钻头的破岩效率,且旋转模块齿交替轮流工作的方式使得切削齿冷却及时,减缓切削齿的磨损,延长钻头寿命。介绍了新型钻头的结构特点和工作原理,对旋转模块进行了变参数实验,实验结果表明:旋转模块随着侧转角的增大,转速增加;随着轴倾角的增大,转速降低。研究得到旋转模块在不同结构参数下的切削载荷以及破碎比功的变化规律,验证了旋转模块齿和固定切削齿“交叉刮切”破碎岩石,能够降低破岩比功,为后续旋转模块式PDC钻头的设计提供理论依据和支撑。 相似文献
14.
Pavement Crack Width Measurement Based on Laplace's Equation for Continuity and Unambiguity 下载免费PDF全文
Wenjuan Wang Allen Zhang Kelvin C. P. Wang Andrew F. Braham Shi Qiu 《Computer-Aided Civil and Infrastructure Engineering》2018,33(2):110-123
Crack is one of the most important pavement condition indicators that are immediately relevant to water ingress and pavement deterioration. In practices of pavement management, crack width has been extensively referenced by highway agencies to determine pavement crack severity. Accurate measurement of pavement crack width is meaningful for highway agencies in understanding the mechanism of crack formation, and in predicting crack propagation. This article presents a new automatic method for measuring crack width using the binary crack map images. The proposed method introduces a new crack width definition and formulates it using the Laplace's Equation so that crack width can be continuously and unambiguously measured. Two algorithms, including the crack blob extraction algorithm and the crack boundary extraction algorithm, are developed to implement the proposed formulation in an automated fashion. Experimental tests using both synthetic data and field data are conducted to demonstrate the accuracy and reliability of the proposed method. A case study on crack width propagation is also performed to demonstrate the practical capacity of the proposed method. The results of the experimental tests and the outcome of the case study have demonstrated that the proposed method, together with the existing crack map extraction algorithms, provides a promising means for consistent and unambiguous crack width measurement supporting automated pavement condition evaluation. 相似文献
15.
基于演化-单纯形算法和结构物理响应反演结构物理参数的方法 总被引:3,自引:0,他引:3
演化计算是上世纪 60年代后基于生物进化的思想发展起来的一类求解优化问题的自适应、自组织、随机搜索的全局优化算法。针对遗传算法、演化策略两种演化计算存在的问题 ,文献 [1]将演化计算与单纯形算法相结合 ,设计了一种基于浮点编码的演化 -单纯形算法。本文将演化 -单纯形算法应用于结构动态反应下的结构物理参数反演分析 ,建立了一种基于时间域实测的结构部分物理响应的结构物理参数反演分析方法。为提高反分析效率 ,文中将物理坐标空间问题转换到模态空间来求解 ,提出了模态演化 -单纯形算法。通过与其它方法的算例比较表明 :本文提出的反演分析方法有精度和搜索效率高、抗燥能力强、对不完全信息情况有很好的适应性等优点。 相似文献
16.
空气钻井中动态破岩有限元仿真研究 总被引:5,自引:0,他引:5
空气钻井技术是以空气作为循环介质的欠平衡钻井技术,其钻头的破岩形式与常规泥浆钻井有很大的区别。在岩石力学和弹塑性力学的基础上,考虑岩石材料的各项异性、地层倾角、钻头与岩石间摩擦因数等影响因素,采用有限元方法建立空气钻井中全尺寸PDC钻头动态破岩的非线性动力学三维模型。通过对空气钻井中岩石的破坏机制和钻头动态破岩过程的研究以及对破岩后形成井眼、井壁和井底岩石应力应变的分析。结果表明:井底岩石受到较大拉应力的作用,使得空气钻井中破岩速度更快;干燥空气钻成的井眼井壁稳定性较好,但是一旦发生井壁不稳定性,井壁岩石将成块掉落。最后通过对钻头上随时间变化的位移分析,得到钻进各向异性地层岩石的井斜和方位的变化规律。本模型为空气钻井的破岩机制、井斜变化规律以及井壁稳定性研究提供一种新的方法,为钻头和钻具设备的研制、优化设计提供理论依据。 相似文献
17.
Ahmad Alhasan David J. White Kris De Brabanter 《Computer-Aided Civil and Infrastructure Engineering》2016,31(12):907-920
Control and characterization of pavement roughness is a major quality assurance requirement. With emerging technologies in real‐time monitoring and increasingly stringent requirements to minimize localized roughness features, there is an opportunity to improve upon the traditional quarter‐car (QC) algorithm used to qualify roughness. Current methods suffer from phase lag that mislocates roughness features and require relatively long profiles to achieve high accuracy. In this study, continuous and discrete wavelet bases were modified in the frequency domain to design 116 new QC‐wavelet filters in the spatial domain that were used to analyze 30 road profiles. QC‐wavelet filters were compared to the currently used finite difference algorithm and filtering in the frequency domain. QC‐wavelet filters design based on a Daubechies and nonanalytic Morlet (i.e., db21 and morl0) wavelets outperformed the other filters and algorithms in terms of characterizing overall profiles and accurately quantifying localized features. The major advantages of the new approach include accurately estimating the position and severity of localized feature, and accurately analyzing short profile segments (i.e., <7.62 m). 相似文献
18.
19.
采用SAP2000软件建立了某景观烟囱的结构分析模型,输入风荷载时程进行风振响应分析。考虑了烟囱复杂外形和不规则质量分布,利用频域方法计算了烟囱第1阶振型的风振位移响应,并与时域方法的结果进行对比,二者吻合较好。分别采用阵风荷载因子法和惯性风荷载法计算了烟囱结构不同高度处的风振系数,并将基于该两种风振系数的等效静力风荷载分别作用在烟囱结构上,计算其顺风向位移响应并与精确值进行比较,结果表明其位移分布均符合真实响应。因此虽然上述两种方法得到的风振系数沿高度分布差别较大,但均能实现烟囱的风振位移等效,均是合理的。为工程应用方便,采用基于阵风荷载因子法的风振系数供结构设计使用。 相似文献