scholarly journals Numerical Simulation of the Stress Field in Repeated Mining of Coal Seams Based on In Situ Stress Measurement

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Donghui Yang ◽  
Bohu Yang ◽  
Zhaoheng Lv ◽  
Yongming Li ◽  
Hongming Cheng ◽  
...  
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Stress Measurement ◽  
Initial Conditions ◽  
Main Roof ◽  
Strength Criterion ◽  
Maximum Principal Stress ◽  
In Situ Stress ◽  
In Situ Stress Measurement

We established an evaluation index of the rock mass stress state for underground coal mines using the strength-stress ratio based on the measured in situ stress and the generalized Hoek–Brown strength criterion. Three in situ stress states, σcm/σ1m < 1.4 (high), 1.4 < σcm/σ1m < 3.6 (medium), and σcm/σ1m > 3.6 (low), were established based on the value of the unconfined compressive strength (σcm) and the maximum principal stress of the rock mass (σ1m). This index classifies the Burtai mine as a medium-high in situ stress field, which is in agreement with the on-site situation, establishing the reliability of the index. The working face was a three-dimensional geological model based on the log sheets. The initial conditions for the model were determined using the combined measurements of the in situ stress regression model. We performed numerical simulations of the roof stress field distribution under repeated mining. Mining the overlying coal seam leads to significant variation in the value and direction of the main roof, σ1, within the range of the front abutment pressure under the pillar and gob. Along the main roof strike direction, σ1 under the pillar is 1.5 times that under the gob, and the σ1 direction under the pillar is deflected by 5°, which is 30° smaller than that under the gob. This provides a reference for optimized underground coal mining.

scholarly journals Study on In Situ Stress Measurement and Surrounding Rock Control Technology in Deep Mine

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhongcheng Qin ◽  
Bin Cao ◽  
Yongle Liu ◽  
Tan Li
Keyword(s):  
Stress Field ◽  
Principal Stress ◽  
Coal Mine ◽  
Maximum Principal Stress ◽  
In Situ Stress ◽  
Measured Data ◽  
Surrounding Rock ◽  
In Situ Stress Measurement ◽  
Surrounding Rock Control

In situ stress is the direct cause of roadway deformation and failure in the process of deep mining activities. The measured data of in situ stress in the Shuanghe coal mine show that the maximum principal stress is 44.94~50.61 MPa, and the maximum principal stress direction is near horizontal direction, which belongs to tectonic stress field. The maximum horizontal principal stress is 1.66~1.86 of the vertical stress. The horizontal principal stress controls the deep stress field. According to the measured data of in situ stress, the high-strength prestress bolt and cable collaborative support form is designed in the Shuanghe coal mine. Based on the stress field research of bolt and cable, the optimal prestress ratio of bolt and cable is proposed as 3. When the prestress ratio of bolt and cable is constant, the smaller the length ratio of bolt and cable is, the better the effect of prestressed field formed by cooperative support is. The results are applied to the support design of the mining roadway in the Shuanghe coal mine. Through the field monitoring test results, it is found that the maximum roof subsidence is 86 mm, the maximum floor deformation is 52 mm, and the maximum deformation of two sides is 125 mm. The surrounding rock control effect of the roadway is good, and the surrounding rock deformation conforms to the engineering technology standard requirements. The research results of this paper can provide some reference for the surrounding rock support of high ground stress mining roadway under similar conditions.

Measurement and the Distribution Law of In Situ Stresses at Deep Depth of Xingcun Coal Mine

2012 ◽  
Vol 450-451 ◽  
pp. 1601-1607 ◽  
Author(s):  
Jiong Wang ◽  
Zhi Biao Guo ◽  
Feng Zhou ◽  
Feng Bin Su ◽  
Bao Liang Li
Keyword(s):  
Stress Field ◽  
Principal Stress ◽  
Coal Mine ◽  
Stress Measurement ◽  
In Situ Stress ◽  
Distribution Law ◽  
Principal Stresses ◽  
In Situ Stress Measurement ◽  
In Situ Stress Field

Many kinds of in situ stress measurement methods are used nowadays, two most common of which are the overcoring and the hydraulic fracturing methods. In order to study the distribution law of in situ stress field in the deep position of Xingcun coal mine, 4 points of in situ stress measurement were carried out in underground roadways at the -1200 m level adopting the overcoring method. The hollow included technique was used to measure the 4 points of in-situ stress. According to the analysis of the measurement data, the results indicated that: (1) Among the three principal stresses on all measurement points, two principal stresses were nearly horizontal and one was nearly vertical. Furthermore, the maximum horizontal principal stress was more than the vertical principal stress, and the magnitude of vertical stress was equal to the weight of overburden rock mass;(2)The value of the maximum horizontal principal stress reached 52.3 MPa , the directions mainly concentrated on the extension of N42°W – N85°W, and the obliquity mainly concentrated on the extension of -29° – 10°;(3)The ratio of maximum horizontal principal stress to vertical principal stress was 1.42 - 1.64 with an average value of 1.55. The result presented that the in situ stress field in Xingcun coalmine at the depth of -1200m was dominated by tectonic horizontal stress. According to the results above, we gained the in situ stress states and the distribution law in the measured region. At the same time, it can offer reasonable basic parameters for underground roadway layout and support design of Xingcun coalmine.

scholarly journals Geological Core Ground Reorientation Technology Application on In Situ Stress Measurement of an Over-Kilometer-Deep Shaft

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chunde Ma ◽  
Xibing Li ◽  
Jiangzhan Chen ◽  
Yanan Zhou ◽  
Sen Gao
Keyword(s):  
Principal Stress ◽  
Stress Measurement ◽  
Stress Relief ◽  
Maximum Principal Stress ◽  
In Situ Stress ◽  
Vertical Stress ◽  
Geometry Model ◽  
In Situ Stress Measurement ◽  
Stress Changes

As mining progresses to depth, engineering activities face the extreme challenge of high in situ stress. To efficiently measure the deep in situ stress before engineering excavation, an innovative deep in situ stress measurement method capable of the geological core ground reorientation technology and acoustic emission (AE) technology was proposed. With this method, nonorientation geological cores collected from the thousand-meter-deep borehole were reoriented based on the spatial spherical geometry model and borehole bending measurement principle. The distribution of deep in situ stress of an over-kilometer-deep shaft in the Xiangxi gold mine was investigated with real-time synchronized MTS 815 material testing machine and PCI-II AE instrument. The results show that the in situ stress changes from being dominated by horizontal stress to being dominated by vertical stress with depth. The horizontal maximum principal stress and vertical stress gradually increase with depth and reach a high-stress level (greater than 25 MPa) at a depth of 1000 m. The direction of the maximum principal stress is near the north. Meanwhile, to analyze the accuracy of the measured in situ stress comparatively, the stress relief measurements were performed at a depth of 655–958 m in the mine, using the Swedish LUT rock triaxial in situ stress measurement system. The distribution of deep in situ stress obtained by the stress relief method agrees well with that by the AE method, which proves the reliability of the AE in situ stress testing method based on the geological core ground reorientation technology.

scholarly journals Analytical Investigation for In Situ Stress Measurement with Rheological Stress Recovery Method and Its Application

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Quansheng Liu ◽  
Jingdong Jiang ◽  
Chengyuan Zhang ◽  
Yuanguang Zhu
Keyword(s):  
Rock Mass ◽  
Initial Stress ◽  
Stress Measurement ◽  
In Situ Stress ◽  
Stress Recovery ◽  
Recovery Stress ◽  
Principal Stresses ◽  
Recovery Method ◽  
In Situ Stress Measurement

In situ stress is one of the most important parameters in underground engineering. Due to the difficulty and weakness of current stress measurement methods in deep soft rock, a new one, rheological stress recovery (RSR) method, to determine three-dimensional stress tensor is developed. It is supposed that rock stresses will recover gradually with time and can be measured by embedding transducers into the borehole. In order to explore the relationship between the measured recovery stress and the initial stress, analytical solutions are developed for the stress measurement process with RSR method in a viscoelastic surrounding rock. The results showed that the measured recovery stress would be more close to the initial stress if the rock mass has a better rheological property, and the property of grouting material should be close to that of rock mass. Then, the RSR method, as well as overcoring technique, was carried out to measure the in situ stresses in Pingdingshan Number 1 coal mines in Henan Province, China. The stress measurement results are basically in the same order, and the major principal stresses are approximately in the direction of NW-SE, which correlates well with the stress regime of Pingdingshan zone known from the tectonic movement history.

Measurement and the Distribution Law of In Situ Stresses of Tingnan Coal Mine

2013 ◽  
Vol 275-277 ◽  
pp. 282-285
Author(s):  
Jiong Wang ◽  
Yang Liu ◽  
Zhi Biao Guo ◽  
Jie Wen Pang ◽  
Bin Liu
Keyword(s):  
Stress Field ◽  
Coal Mine ◽  
Stress Measurement ◽  
Tectonic Stress ◽  
In Situ Stress ◽  
Dominant Factor ◽  
Distribution Law ◽  
In Situ Stress Measurement ◽  
In Situ Stress Field

In order to study the distribution law of in situ stress field of Tingnan coal mine, 4 points of in situ stress measurement were carried out in underground roadways at the -450 m level with the overcoring method. The KX-81 type cell was used to measure the 4 points of in-situ stress. According to the analysis and calculation of the measurement result, the dominant factor of the in situ stress field in Tingnan coal mine at the depth of -450m is horizontal tectonic stress.

In-Situ Stress Measurement and Tectonic Stress Field in the Lanzhou-Maqu Region of China

2008 ◽  
Vol 51 (5) ◽  
pp. 1031-1038 ◽  
Author(s):  
Man-Lu WU ◽  
Yin-Sheng MA ◽  
Chun-Shan ZHANG ◽  
Chun-Ting LIAO ◽  
Ming-Yi OU
Keyword(s):  
Stress Field ◽  
Stress Measurement ◽  
Tectonic Stress ◽  
In Situ Stress ◽  
Tectonic Stress Field ◽  
In Situ Stress Measurement

Measurement and the Distribution Law of In Situ Stresses at Deep Depth of Hongyang Coal Mine

2013 ◽  
Vol 671-674 ◽  
pp. 65-68
Author(s):  
Hong Man Xia ◽  
Jiong Wang ◽  
Yang Liu ◽  
Jie Wen Pang ◽  
Dong Qiao Liu ◽  
...  
Keyword(s):  
Stress Field ◽  
Coal Mine ◽  
Stress Measurement ◽  
Measurement Data ◽  
Tectonic Stress ◽  
In Situ Stress ◽  
Distribution Law ◽  
In Situ Stress Measurement ◽  
In Situ Stress Field

There are many in situ stress measurement methods nowadays, the ISRM suggested two methods for in situ stresses measurement: overcoring methods and the hydraulic fracturing methods. In order to study the distribution law of in situ stress field in the deep position of Hongyang coal mine, 3 points of in situ stress measurement were carried out in underground roadways at the -870 m level adopting the overcoring method. The KX-81 type gauge was used to measure the 3 points of in-situ stress. According to the analysis and calculation of the measurement data, the result showed that the in situ stress field in Hongyang coal mine at the depth of -870m was dominated by horizontal tectonic stress.

In Situ Stress Measurement and Inversion in Deep Roadway

2013 ◽  
Vol 734-737 ◽  
pp. 759-763 ◽  
Author(s):  
Yong Li ◽  
Yun Yi Zhang ◽  
Ren Jie Gao ◽  
Shuai Tao Xie
Keyword(s):  
Field Measurement ◽  
Stress Measurement ◽  
Measurement Data ◽  
Back Analysis ◽  
In Situ Stress ◽  
Deep Mine ◽  
Accuracy Requirement ◽  
Initial Stress Field ◽  
In Situ Stress Measurement

Jixi mine area is one of the early mined areas in China and it's a typical deep mine. Because of large deformation of underground roadway and dynamic disasters occurred frequently in this mine, five measurement points of in-situ stress in this mine was measured and then analyzed with inversion. Based on these in-situ stress measurement data, numerical model of 3D in-situ stress back analysis was established. According to different stress fields, related analytical samples of neural network were given with FLAC program. Through the determination of hidden layers, hidden nodes and the setting of parameters, the network was optimized and trained. Then according to field measurement of in-situ stress, back analysis of initial stress field was conducted. Compared with field measurement, with accuracy requirement satisfied, it shows that the in-situ stress of rock mass obtained is basically reasonable. Meanwhile, it proves that the measurement of in-situ stress can provide deep mines with effective and rapid means, and also provide reliable data to optimization of deep roadway layout and supporting design.

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