共查询到19条相似文献，搜索用时 187 毫秒
1.
简要介绍高密度电法在天津软土地基勘察中的应用情况。分析天津软土地基的特点及地球物理前提条件，用典型实例说明高密度电法可以探查城市地下管道、了解地层起伏、探查沟坑变化、探测地基土均匀性等。发现并揭示了天津地区视电阻率与地基土物理力学指标之间的相关规律。同时估计了高密度电法可能的应用范围。 相似文献
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建筑场地地震液化危害评价及地基处理 总被引：5，自引：2，他引：3
本文分析了地基失稳,计算震陷值及差异震陷等地基失效形式和液化土层的隔震作用,研究了液化指数、地基失效、液化土层隔震与多层房屋震害的关系,根据液化土的双重作用原理划分了液化危害等级,并提出了建筑场地地震液化危害评价方法和按小震不坏,中震可修,大震不倒的抗液化处理原则。 相似文献
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场地原位试验的工程应用 总被引：3，自引：0，他引：3
以天津院综合楼地基勘察为实例，较详细地介绍了剪切波速法，标准贯入法，静力触探法等闰试验技术在场地类别划分及地基土液化判别中的应用，并对有关问题进行了探讨。 相似文献
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冲击碾压法处理粉土地基试验研究 总被引：3，自引：0，他引：3
冲击碾压法作为一种高效、经济的压实技术,已经广泛应用于各种路基压实和软基处理等领域,并不断被应用于新的领域。通过现场试验,结合试验过程中地下水位、地表沉降和孔隙水压力等项目的监测结果以及处理后标准贯入试验和静力触探试验的检测成果,探讨了冲击碾压法用于消除浅层粉土地基液化的有效性和相应的施工工艺。试验研究表明,采用冲击碾压法可消除浅层粉土地基的液化,并且2 m深度范围内地基土的压实效果明显。研究成果证明了冲击碾压法在消除浅层地基液化领域的适用性。 相似文献
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本文简要介绍了高密度电法与音频大地电磁法在吉舒铁路路基勘测中的应用效果。通过采用不同方法对不同视电阻率的岩土界面加以区分,分析吉舒铁路路基在不同岩土地层条件下的特点及地球物理特性,在吉舒40 km (K49-633-753)段应用高密度电法与音频大地电磁法了解地层起伏、探查岩土上下层电阻率变化、探测地基土均匀性等,发现并揭示了吉舒铁路路基视电阻率与地基土地球物理指标之间的相关规律。同时揭示了铁路路基发生地质灾害的机理。 相似文献
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黄土湿陷过程中微结构变化规律的电阻率法定量分析 总被引：8，自引：0，他引：8
针对现代土力学中土的微结构定量分析的困难,考虑到电阻率法在土的微结构研究中的突出优点,引入电阻率法进行黄土湿陷过程中的微结构变化规律定量分析,探讨土电阻率法在土的微结构定量研究中的应用。以典型的非饱和黄土为研究对象,通过同步测定黄土湿陷过程中土样的竖向与横向电阻率大小,计算出土电阻率结构性参数指标,包括土的竖向与横向结构因子、平均结构因子、各向异性系数与平均形状因子的大小,分析了黄土湿陷过程中土电阻率结构性参数的变化规律,建立了定量描述黄土微结构变化规律的电阻率评价方法。试验研究表明,土的电阻率法具有连续、快捷与测试方便等诸多优点,通过土的电阻率结构性参数指标的研究,可有效进行土的微结构变化定量分析。 相似文献
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地震引起的土体液化和地基失效对岩土工程师而言仍是一个热点问题。地震液化及地基变形可以采用多种地基加固方法防治,碎石桩技术是常用方法之一。碎石桩复合地基抗液化效用主要是增加桩周土体的密度、桩体的排水以及桩体分担地震水平剪应力作用(桩体减震作用)。目前,以抗液化为主的碎石桩复合地基的设计以及效果评价方法仍只考虑加密作用。首先通过3个模型(1个饱和砂土地基模型、2个碎石桩复合地基模型)的振动台试验研究抗液化碎石桩的减震作用。然后以试验记录的模型动力反应以及建立的理论模型为基础,分析碎石桩复合地基的桩体减震作用。试验及理论分析结果表明,复合地基中的碎石桩可以明显地降低作用在桩间可液化土上的地震剪应力。 相似文献
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In this study, the effect of diesel fuel contamination on the electrical properties of unsaturated soils was estimated in
the low frequency ranges. For the soils having 5% water content, the electrical resistivity increased with the diesel fuel
contents while the permittivity decreased at higher diesel contents. However, at 15% water content, the variation of electrical
properties was not significant possibly because most of the electric currents should occur through the pore water. The linear
relationship between the electrical resistivity and the diesel fuel contents in soil was developed at 5% water content, which
implied that the electrical resistivity could be used to quantify the extent of diesel fuel contamination in soil. The results
indicated that the electrical properties including the resistivity and the permittivity could give the reliable estimation
on the diesel contamination with the low water content in soil and the frequency applied below 1 MHz. 相似文献
12.
电阻率法评价膨胀土改良的物化过程 总被引：4，自引：1，他引：3
掺石灰、粉煤灰是工程中通常采用的改良膨胀土的方法。土电阻率是土的基本物理指标之一,其变化可反映土的其他物理性质指标的变化。通过掺灰改良膨胀土不同养护龄期下的电阻率测试以及膨胀量、膨胀力及无侧限抗压强度等试验研究,探讨了掺灰改良膨胀土养护过程中的物理化学反应过程。根据养护过程中的电阻率随龄期的变化规律,可将改良膨胀土的物理化学反应过程划分为瞬时反应阶段、主体反应阶段、残余反应阶段和稳定阶段4个不同阶段。针对改良膨胀土质量控制和评价体系中存在的不足,提出了基于电阻率指标的改性膨胀土的质量评价方法,通过试验证实了该方法的有效性和实用性。 相似文献
13.
The city of Burdur, which is built on an alluvium aquifer, is located in one of the most seismically active zones in southwestern
Turkey. The soil properties in the study site are characterized by unconsolidated and water-saturated sediments including
silty, clayey and sandy units, and shallow groundwater level is the other characteristic of the site. Thus, the city is under
soil liquefaction risk during a large earthquake. A resistivity survey including 189 vertical electrical sounding (VES) measurements
was carried out in 2000 as part of a multi-disciplinary project aiming to investigate settlement properties in Burdur city
and its vicinity. In the present study, the VES data acquired by using a Schlumberger array were re-processed with 1D and
2D inversion techniques to determine liquefaction potential in the study site. The results of some 1D interpretations were
compared to the data from several wells drilled during the project. Also, the groundwater level map that was previously obtained
by hydrological studies was extended toward north by using the resistivity data. 2D least-squares inversions were performed
along nine VES profiles. This provided very useful information on vertical and horizontal extends of geologic units and water
content in the subsurface. The study area is characterized by low resistivity distribution (<150 Ωm) originating from high
fluid content in the subsurface. Lower resistivity (3–30 Ωm) is associated with the Quaternary and the Tertiary lacustrine
sediments while relatively high resistivity (40–150 Ωm) is related to the Quaternary alluvial cone deposits. This study has
also shown that the resistivity measurements are useful in the estimation of liquefaction risk in a site by providing information
on the groundwater level and the fluid content in the subsurface. Based on this, we obtained a liquefaction hazard map for
the study area. The liquefaction potential was classified by considering the resistivity distributions from 2D inversion of
the VES profiles, the types of the sediments and the extended groundwater level map. According to this map, the study area
was characterized by high liquefaction hazard risk. 相似文献
14.
The paper identifies and discusses potential adverse environmental impacts, and regulatory concerns, that could arise from piling or penetrative ground improvement techniques, when used on land affected by contamination.
A common generic classification of piling and penetrative ground improvement methods is considered and six cases are identified where potential adverse environmental impacts may be created by piling or penetrative ground improvement techniques.
A lack of published data on the scale of impacts caused by piling makes inevitable the application of the “Precautionary Principle” by environmental regulators, but it has been recognised that a rigid application of this principle may lead to unnecessarily restrictive requirements or prohibitions being placed on designers and developers. The need for guidance for designers and developers on how to consider the potential environmental impacts of piling works has also been recognised.
The paper outlines the decision-making framework presented in recent Environment Agency guidance. It assists the foundation designer to assess the environmental risks, select an appropriate piling or penetrative ground improvement method, develop mitigation measures, define quality assurance/quality control and monitoring measures, and justify and document this choice in a format acceptable to the regulator. 相似文献
15.
掺石灰黏土电阻率试验研究 总被引：3，自引：0，他引：3
利用4电极电阻率测量装置,在室内对各种灰土样的电阻率进行测试对比研究,揭示了不同因素如灰土比、含水率、饱和度、土的结构和土粒粒径等对灰土样电阻率的影响。在不同含水率（15 %、20 %、25 %和30 %）条件下,素土及其与不同石灰掺量（1:10、1:15和1:30）的混合,通过轻型击实试验后,测量其横向及竖向断面上的电阻率,研究电阻率与不同石灰配比击实土样的物理力学性质之间的关系。实验结果表明,当含水率在15 %~20 %之间时,较小的含水率增量引起混合土样电阻率的大幅度下降;当含水率约达到20 %后,其电阻率随含水率的继续增加而减小的幅度很小;在15 %含水率时,掺灰土电阻率比素土样高;在30 %含水率时,其电阻率低于素土样,而且掺量越大,电阻率越低;由于击实导致土体颗粒的结构重新排列,电阻率在横向上大于竖向;电阻率随着无侧限抗压强度的增加而增加,在电阻率大于50 ?•m时,电阻率随无侧限抗压强度的增加而减小;饱和度、干密度与电阻率呈负指数变化规律,孔隙率、孔隙比与电阻率呈指数变化规律;含水率对于电阻率的影响较为敏感。 相似文献
16.
为了提高电阻率法对地下介质污染问题的探测能力,分析了含油污水污染地下介质后引起的导电性变化,建立了适用于该问题分析的地电模型。利用2.5维有限元的方法正演模拟了采用温纳、施龙贝格、偶极和二极装置监测时所得的典型电异常剖面。正演模拟结果显示不同装置对污染区的反映能力不同,相对而言施龙贝格和温纳装置对污染区分布的反映较为直观。饱和粘土的含油污染区用温纳装置测量,剖面上表现为相对高阻异常特征,异常区域分布和污染通道相吻合。应用实例也证实了这一分析。 相似文献
17.
Assessing aquifer vulnerability to pollutants by electrical resistivity tomography (ERT) at a nitrate vulnerable zone in NE Spain 总被引：1，自引：0，他引：1
There is an increasing demand for groundwater vulnerability maps which illustrate the exposure of aquifers against pollution.
These maps show areas of greatest potential for groundwater contamination on the basis of local subsurface conditions. Parameters
affecting vulnerability are mainly permeability and thickness of each protective layer. For unconsolidated sediments, the
permeability is strongly related to the clay content, which can be deduced from indirect resistivity methods, like electrical-imaging.
Such geophysical methods can be of great help in groundwater vulnerability studies because they disturb neither the structure
nor the dynamics of the soil. Sensibility analysis was performed of the electrical resistivity tomography method for accurately
mapping soil media. Managers and public administrators may effectively use this method for assessing the potential risk of
groundwater contamination. In the studied zone, electrical resistivity exhibits a wide range of variability that can be easily
correlated to soil parameters, such as clay content and hydraulic conductivity. A numerical index of protection has been assessed
from the geophysical information derived from 2D electrical resistivity tomography. This work represents a preliminary approach
on the natural vulnerability evaluation of shallow aquifers at the Empordà basin (NE Spain) that is highly affected by diffuse
pollution by nitrates. 相似文献
18.
电阻率孔压静力触探(RCPTU)除了包含常规的孔压静力触探测试功能之外,还可以提供连续的电阻率变化曲线,因而在环境岩土工程领域具有广阔的应用前景。电阻率是表征土体导电性的基本参数,是土的固有物性之一,每种类型的土都有固有的电阻率,其变异可能意味着受到污染。本文根据某农药厂污染场地的RCPTU试验结果,分析了不同污染物类型对电阻率的影响,并初步研究了基于电阻率指标的污染物分布与污染程度的鉴别。考虑到孔隙比或相对密实度对土体积电阻率也会产生较大影响,利用RCPTU可测相对密实度的优点,本文提出可将实测电阻率值等效至某一特定的相对密实度下,再将等效电阻率值与相应的背景值进行对比分析,根据等效电阻率值与背景值的偏差量与偏差率进行污染范围与污染程度的确定。结果表明电阻率指标能够精确反应污染物的存在与受污染的程度。 相似文献