scholarly journals Experimental Study on the Flow Behavior of Grout Used in Horizontal Directional Drilling Borehole Grouting to Seal Mining-Induced Overburden Fractures

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jinfeng Ju ◽  
Jialin Xu ◽  
Jing Yang
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Flow Behavior ◽  
Groundwater Resources ◽  
Rock Fracture ◽  
Mining Area ◽  
Tensile Failure ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
Fracture Types

The development of water-conducting fractures from underground coal mining is a geological cause of groundwater loss. Sealing mining-induced rock fracture channels through borehole grouting is an effective way to protect groundwater resources. A ground-based engineering test was conducted at the Gaojiabao coal mine that utilized horizontal directional drilling (HDD) to grout and seal water-conducting overburden fractures. This study carried out a theoretical and experimental exploration using HDD to evaluate the development characteristics and grout hydraulic conductivity of these mining-induced fractures. The results showed that, as a result of varying fracture morphologies in different zones of the mining overburden, multiple fracture types were sequentially exposed as the HDD borehole advanced from the original rock mass outside the mining area towards the mining-induced fractured rock mass. The fracture types were exposed in the following order: compressive shear fractures, tensile failure fractures, and bed separation fractures. Moreover, the void characteristics of the exposed fractures in the borehole were significantly different at different drilling horizons, which affected the flow behavior and sealing performance of the injected grout. Lastly, three typical orders in which the different types of fractures were sequentially exposed by the borehole were summarized, and further analysis of the orders led to a scheme for determining drilling horizons favorable for efficient fracture sealing. The results of this study will enable efficient grout sealing of the fractures caused by mining and reduce groundwater loss.

Study of Seepage Properties of Fractured Rock Mass Based on Improved K-Means Clustering Algorithm

2013 ◽  
Vol 405-408 ◽  
pp. 310-315
Author(s):  
Hai Qing Guo ◽  
Bo Wen ◽  
Xiao Feng Bai
Keyword(s):  
Rock Mass ◽  
Clustering Algorithm ◽  
Fractured Rock ◽  
Rock Fracture ◽  
Fractured Rock Mass ◽  
Dam Foundation ◽  
Fracture Geometry ◽  
Basic Task ◽  
Matlab Program ◽  
Seepage Properties

Seepage properties of fractured rock mass are of prime importance for hydraulic engineering and accurate description of rock fracture geometry parameters is an important and basic task in rock hydraulics. In this paper, an improved K-means clustering algorithm for structural plane of fractured rock mass was first brought forward and the corresponding Matlab program for discontinuity orientations partitioning was compiled and then used in the fitting analysis of dominant orientations of certain dam foundation rock mass. On this basis, combining calculation formulas of multi-group fractures, the permeability tensor and principle value was calculated for the actual dam foundation. The results provide a theoretical and computational reference for other similar projects.

scholarly journals Failure Mechanisms of Brittle Rocks under Uniaxial Compression

2017 ◽  
Vol 47 (3) ◽  
pp. 59-80 ◽  
Author(s):  
Taoying Liu ◽  
Ping Cao
Keyword(s):  
Rock Mass ◽  
Crack Initiation ◽  
Failure Mechanism ◽  
Shear Crack ◽  
Fractured Rock ◽  
Rock Fracture ◽  
Wing Crack ◽  
Rock Bridge ◽  
Brittle Rocks ◽  
Shear Connection

AbstractThe behaviour of a rock mass is determined not only by the properties of the rock matrix, but mostly by the presence and properties of discontinuities or fractures within the mass. The compression test on rock-like specimens with two prefabricated transfixion fissures, made by pulling out the embedded metal inserts in the pre-cured period was carried out on the servo control uniaxial loading tester. The influence of the geometry of pre-existing cracks on the cracking processes was analysed with reference to the experimental observation of crack initiation and propagation from pre-existing flaws. Based on the rock fracture mechanics and the stress-strain curves, the evolution failure mechanism of the fissure body was also analyzed on the basis of exploring the law of the compression-shear crack initiation, wing crack growth and rock bridge connection. Meanwhile, damage fracture mechanical models of a compression-shear rock mass are established when the rock bridge axial transfixion failure, tension-shear combined failure, or wing crack shear connection failure occurs on the specimen under axial compression. This research was of significance in studying the failure mechanism of fractured rock mass.

Study on Tensile-Shear Failure of Fractured Rock Mass under Strong Seismic Load

2011 ◽  
Vol 243-249 ◽  
pp. 2607-2612
Author(s):  
Guo Sheng Lu ◽  
Xun Wang ◽  
Xiao Lan Chen
Keyword(s):  
Rock Mass ◽  
Shear Failure ◽  
Fractured Rock ◽  
Rock Fracture ◽  
Circumferential Stress ◽  
Seismic Load ◽  
Tensile Shear ◽  
Fractured Rock Mass ◽  
Stress Theory ◽  
Seismic Force

Fractured rock mass endures tensile-shear and pressure-shear effects under horizontal seismic force. Based on rock fracture mechanics and the maximum circumferential stress theory, the extending condition (that is, the critical acceleration), the extending direction and the crack extension length under different direction of horizontal seismic force have been studied. The results are useful for judging the risk of dangerous rocks and providing a theoretical basis of pre-identification in the earthquake zone.

scholarly journals Experimental Study of Joint Roughness Influence on Fractured Rock Mass Seepage

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zhongxi Tian ◽  
Chunquan Dai ◽  
Qingshuang Zhao ◽  
Zhaobo Meng ◽  
Baoliang Zhang
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Water Pressure ◽  
Rock Fracture ◽  
Single Fracture ◽  
Fractured Rock Mass ◽  
Joint Roughness ◽  
Joint Surfaces ◽  
The Mean ◽  
Mean Variance

Surrounding rock pressure, water pressure, and joint roughness are the important factors that affect the fractured rock mass seepage. It is of great significance to quantify the influence of these factors through experiments. In this study, rock fracture joint surfaces were measured. Next, 3D coordinates of joint surfaces were extracted with using the Geomagic software, and joint roughness was described using the mean variance of protrusion height and equidistant fluctuation angle, which were acquired through calculation. Stress-seepage coupling test was then conducted on the samples on a triaxial apparatus, and the effects of confining stress and water pressure on the permeability of single-fracture rock were investigated. On the basis of the relationship between the parameters in data fitting expression and the mean variance of protrusion height and equidistant fluctuation angle, the calculation formula of the permeability coefficient including joint roughness, confining pressure, and seepage pressure difference was derived.

Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

2020 ◽  
pp. 67-75
Author(s):  
Van Min Nguyen ◽  
V. A. Eremenko ◽  
M. A. Sukhorukova ◽  
S. S. Shermatova
Keyword(s):  
Rock Mass ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rock Fracture ◽  
Strain Analysis ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Secondary Stress ◽  
Principal Stresses ◽  
Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

EMERGENCY RESPONSE IN THE PIPELINE CONSTRUCTION BY HORIZONTAL DIRECTIONAL DRILLING

2015 ◽  
pp. 91-96
Author(s):  
I. E. Kiryanov ◽  
Yu. D. Zemenkov ◽  
S. M. Dorofeev ◽  
V. S. Toropov
Keyword(s):  
Emergency Response ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
Pipeline Construction ◽  
Trenchless Construction

On the basis of analyzing the characteristics of used materials and the parameters of trenchless transitions profiles was developed emergency response, including several schemes of release a pipe jammed in the hole during the pipeline pulling in the pipeline construction by horizontal directional drilling. Proposed schemes applicability analyzed for trenchless construction real conditions.

Evaluation of Hydraulic Fracturing Models and Their Limitations to Predict No-Drill Zones for Horizontal Directional Drilling

2018 ◽  
Author(s):  
Saeed Delara ◽  
Kendra MacKay
Keyword(s):  
Hydraulic Fracturing ◽  
Safety Factor ◽  
Standard Procedure ◽  
Accurate Determination ◽  
Strength Properties ◽  
Analytical Models ◽  
Alternative Methods ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
The Impact

Horizontal directional drilling (HDD) has become the preferred method for trenchless pipeline installations. Drilling pressures must be limited and a “no-drill zone” determined to avoid exceeding the strength of surrounding soil and rock. The currently accepted industry method of calculating hydraulic fracturing limiting pressure with application of an arbitrary safety factor contains several assumptions that are often not applicable to specific ground conditions. There is also no standard procedure for safety factor determination, resulting in detrimental impacts on drilling operations. This paper provides an analysis of the standard methods and proposes two alternative analytical models to more accurately determine the hydraulic fracture point and acceptable drilling pressure. These alternative methods provide greater understanding of the interaction between the drilling pressures and the surrounding ground strength properties. This allows for more accurate determination of horizontal directional drilling limitations. A comparison is presented to determine the differences in characteristics and assumptions for each model. The impact of specific soil properties and factors is investigated by means of a sensitivity analysis to determine the most critical soil information for each model.

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