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GD-10 Application Cave Survey

1. Test purpose

The GD-10 electric instrument was used to conduct geological disasters investigation in a certain area of ​​Jiujiang County to identify the development of earth caves, karsts and faults in Quaternary area.

Test parameters

The high-density electrical method to GD-10 multi-function electrical system as the host, the electrode device using Winner α device. GD-10 instrument spacing factor of 1, the maximum spacing factor of 39, the electrode spacing of 5m, profile length of 600 meters, a total of 120 ways to measure the layout.

3. Work Area Overview

The geophysical prospecting area of ​​the topography is mainly erosive hills terrain, the overall trend of the mountain to the north east.

According to the regional geological data, combined with other geological survey data, the stratigraphic lithologies in the survey area include Quaternary silty clay and limestone.

4. Work area geophysical characteristics

According to the regional geological data and field measurements, the geotechnical properties of the site are relatively complex. The resistivity of Quaternary is generally n × 10Ω · M. The resistivity of underlying bedrock is generally in the range of n × 102 ~ n × 103Ω · M. Quaternary soil resistivity values ​​vary greatly by their own composition and degree of water content, generally loose high water content, low resistivity value, and vice versa. The resistivity value of bedrock is relatively high. When the fractured zone is developed and contains some water, the resistivity value obviously decreases, and there is a certain electrical difference with the surrounding rock.

5. Data Analysis and Interpretation

Field measured data will be transmitted to the computer, through special processing software, field data measured point mutation processing, terrain correction and other operations into the map.

Before the measurement, we must first conduct an electrode grounding resistance test, grounding resistance are normal, begin data acquisition and measurement.

According to the high-density resistivity chromatogram, there is a relatively low-resistivity anomaly with a resistivity of 6-42.4Ω · M at a depth of 9.47-32 meters at the point of 150-165 meters, which is interpreted as a cave. At the point At 355-380 m, there is a relatively low-resistivity zone, interpreted as a karst fissure zone; at depths of 480-505 at depths of 5-14.5 m at depths of 515-525 at depths The resistivity is relatively low at 6-14.5 meters below ground, explaining the inferred karst loose zone.

In order to validate the survey results of GD-10, borehole verification was carried out in the 150-165m area. The results show that this area is indeed a karst cave development zone, and the depth and scale of GD-10 delineation and the actual drilling data show The results are basically consistent.

 

 

A foundation of a temple depth survey

1. Test purpose

The GD-10 high-density electrical method instrument is used to investigate the foundation of a nearby temple. The 2D high-density resistivity profile test method is mainly used to test the profile of the ground surface around the tower. Since high-density exploration depth is relatively shallow, but high resolution, the observed resistivity change interface to detect the substrate interface, the depth of the substrate.

Test parameters

In this test, a total of 6 high-density measurement lines are arranged, using a wennerα device with a distance of 1 meter and a total of 48 channels.

3 test results analysis

This data is processed using res2dinv inversion software

According to the inversion results, we can see that there is a clear boundary between high and low resistance at the depth of 1.5m, suggesting that this area is the base of the temple. Low resistance for the Quaternary. GD10 can accurately divide the foundation structure of the temple foundation and clarify the depth of the basement.

Leakage detection of dam tailings in a tailing pond

1. Test purpose

The work area is mainly 1 # tailings ponds and their surrounding ore mines and solid waste sites, the study of the surrounding leaking situation, the detection of pre-dam, earth dam and other anti-seepage projects are intact, whether it can effectively prevent the seepage of wastewater Leakage and aging areas where leakage may occur; identify the scope of the area where the seepage has occurred, determine the width and depth of the seepage, and delineate the target area for the leakage so as to provide the basis for the next environmental protection project. The means of exploration mainly for high-density electrical measurement, into the instrument for the production of our GD-10 high-density resistivity measurement system.

Test parameters

The high-density electrical measurement for the # 1 tailings pond and the surrounding area has been leaking six sections laid; peripheral ore pile layout of a section; two solid waste sites each laying a total of 9 profile lines laid. Geophysical prospecting lines are laid out in the principle of vertical stratigraphic strike, structural zone and fractured karst development zone. RTM and fast static observation are used to locate the measuring point. The measuring device uses Wenner α. Electrode pitch 2-3m, the total number of arranged electrodes determined according to the site, the detection depth greater than 45m. Before the measurement, we must first conduct an electrode grounding resistance test, grounding resistance are normal, begin data acquisition and measurement.

3. Data processing and interpretation

G1 line:

According to the high-density resistivity chromatogram analysis, the survey line is located on the dam. In the past, there was a leakage situation in the anomaly ① and reinforcement in the later stage. From this result, the apparent resistivity polar point is below 20 ohm , Speculated that there may still be leaks.

The low resistivity zone in the anomalous zone ② is strip-like with a steeper dip angle, with apparent resistivity of 20-50.

G2 line:

Based on the high-density resistivity chromatogram, the survey line is located on the upper lobe of the dam with a spacing of about 3 meters from the G1 line. The abnormal zone ① corresponds to the abnormal position ① of the G1 section, and is presumed to be the same leaking zone. Leakage area has increased, indicating that the water leakage belt along the downward trend has expanded.

G4 line:

Analysis of the resistivity chromatogram by high-density electrical method, there is a low resistance in the No. 1 area, which is presumed to be a water-conducting channel.

The anomalous area of ​​No. 2 is presumed to be a water leakage area with water accumulation on the surface and a water reservoir on the side. It is suspected that the water leakage at the bottom of the reservoir is presumed to be a fissure, and tends to be near north and south and westwards.

There is a ditch on the surface of the No. 3 area, and the direction of the ditches at this location is basically the same with that of the survey line, suggesting that the anomaly is caused by the ditch.

G5 line:

由高密度电法电阻率色谱图分析,①表有积水,向下浸透约10米深度,推测该处可能有裂隙。②号区域为渣石场与防水工程接触部位,地表有一水沟,推测接触部位不严密,存在缝隙,地表水沿缝隙向深部泄漏。③号高阻区以往开展了防水加固工程,目前来看,该防水工程未出现漏水现象。④号区域地表可见水沟,且该处存在一断裂,近北西向,倾向南西,与④号低阻带形态一致,推测引起异常原因为水流沿构造向深部渗透。

G6线:

由高密度电法电阻率色谱图分析,①异常距地表深约20米,推测为渗水通道,

②号异常位置地表有水沟,与G4的③号异常和G8的②号异常对应,均为流经的水沟侵蚀所致。③号低阻异常区推测该位置可能存在断裂,倾向南,地表水经断裂向下浸透。

G7线:

 

由高密度电法电阻率色谱图分析,①地表为观景台和溜渣井,均为铁质建造,推测该处异常可能为雨水通过溜渣井流向深部。②及③两处地下均建有排水管,管内流水量大,水源主要为雨水及固废场地积水。

G8线:

由高密度电法电阻率色谱图分析,①号低阻异常区与G4测线②号异常对应,两条测线相隔10米,推测蓄水池的水经G4剖面已蔓延至G8剖面。②号异常与G4线③号异常对应,推测因水沟常年流水所致③号区域处地表存在一蓄水池,推测异常由该蓄水池引起。

G9线:

由高密度电法电阻率色谱图分析,①号区存在一个低阻带状异常,推测为漏水区域,②号区域推测可能为导水通道。

台湾湖山水库湖南坝

1. 测试目的

为了检测大坝是否存在异常渗漏区以及内部整体结构探测。

2. 测试场址及布置

湖山水库为丘陵地带,大致呈南-北走向,北端为刀尖形触口山脉,南北长约14公里,东西宽月4至5公里,全区为500公尺一下的低平丘陵。本丘陵以砾岩与软弱啥,页岩所构成,为以背斜山岭,砾岩层分布于丘陵北部与东部。坝顶宽度10米,坝顶高程216米,坝体上游坡面坡度以高程203.0米为界,大坝下游坡面坡度以高程205.0米为界。

目前水库安全检查主要仰赖定期与非定期的水库安全检查与评估工作,而此评估工作大部分尚以目视以及监测资料作为最直接的第一手安全诊断基础,这些方法主要是以显露与构造物表面的状态来进行判断,并不能提供构造物内部的损害情形以及可能损害范围及其路径过程,因此考虑非破坏性大面积施做的地球物理方法作为检查和监测的辅助工具。

测线布置

①平行于坝体坝面

施作主要目的为检测水平断面坝体内是否具有结构性裂缝,以及一些渗漏区,较大孔洞,采用潜在破坏模式分析方式进行2D高密度电阻率测试,施测面离坝底高度约为60m,故需探测深度为60m,整个坝面长度为420m,大坝常规作业探测不仅需要深度的解析资料,更是对水平方向的分辨率有着一定的要求,因此选用ws装置进行探测,ws探测深度约为0.19*测线长度,可达70m左右,符合监测所需深度,并且满足了水平和垂直分辨率足够。

GD-10使用80根电极。电极间距5米,发射电压150V。

②垂直于坝体

垂直测线布置主要虽不易监测整体坝体未来可能发生的安全检查问题,但可以在未蓄水前作为背景值,与蓄水过程或者蓄水后进行对比,协助监测坝体内部的变化情形,有助于工程检核。

3. 数据结果

从反演图中可以红色框中低阻区为植被覆盖区,施测时已有一段时间未下雨,故除了植被覆盖区域外,其他地方并未呈现过低电阻,属于正常状态。而红色圈内高阻区域主要为混泥土地下排水管。

某地GD10与AGI高密度电法仪测量对比案例

1.测试目的

对比GD10电法系统与AGI高密度电法仪的性能。

探测工作区域滑坡体分布范围,滑坡体分层,探测滑坡体内部饱水带,含水层的分布和埋深。

2.测试参数

本次工作是用于对比GD-10电法仪和AGI电法仪测试性能及精度等,施作时沿着滑移区布设了1条测线。测试选用Wenner α、Schlumberger以及Dipole-dipole装置。电极间距为5m,总道数为36道。在测量前,首先要进行电极接地电阻检测,接地电阻均正常后,开始进行数据采集。

3. 数据处理与结论

本次高密度电阻率对比测试,布设1条测线,数据处理采用AGI的EarthImager 2D反演软件,对比情况如下。

Wenner α装置对比反演图(a)GD10电法系统(b)AGI高密度电法仪

Schlumberger反演图(a)GD10电法系统(b)AGI高密度电法仪

Dipole-dipole对比反演图(a) GD10电法系统(b)AGI高密度电法仪

根据反演结果可知,GD10电法仪的 Dipole-dipole脚本增加了测量点数,加深了对深层资料的解析,通过对于小信号资料点的优化处理,在测量总长度及分辨率相同的情况下,可以比AGI多往下探测20m左右。

同时,从反演结果图像知,GD10与AGI的都能明显的刻画出地层的层状结构,高低阻电性界面明显,且结果基本一致。由于天气干旱,降雨量很少,黑方台上部黄土长期处于干燥状态,天然含水率一般小于10%,因此反演结果图中均可得到上部约1-9m处呈中高阻状态,如图中红色区域,判定为风积黄土,以粉粒为主,土质均一,疏松多孔,且土中含盐量较高,符合其区域地质环境。

GD-10电法仪可查看测试数据、散点图、拟合图、电压电流曲线以及方差等,可现场实时判断数据质量,同时采用自动迭代方式提高精度。

 

GD10物探电性试验场测试

1.测试目的

GD10高密度电法仪测试效果验证

2.测试参数

测试装置:wennerα装置,点距:1m,道数:96道,发射周期:1s

3.测试场地电性模型结构

本次测试场地为某区专用物探电性试验场地,下图为场区电性结构模型图

测试场地电性模型结构,2个异常模型分别埋设在标尺26-28位置及58-60位置。由于异常模型都掺了石墨粉所以都呈现低阻反演。同时填埋的异常模型极浅,基本紧贴地表。

4.数据分析

反演结果分析:

The inversion results show that there are low resistivity zones (anomalous zones) with apparent resistivities of about 30 to 37.6Ω • m in the region from 26m to 28m in the depth of about 0.6 inner zone. At the same time, low resistivity zones (anomalous zones) with apparent resistivities of about 15 to 30 Ω • m appear in the 38m to 60m zones with an inner depth of about 0.7. Based on the analysis of the electrical structure of the test site, the two abnormal site test sites were buried in the model. Because the test results and the actual situation is basically the same.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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