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MT/T 1091-2008 PDF in English

MT/T 1091-2008 (MT/T1091-2008, MTT 1091-2008, MTT1091-2008)
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MT/T 1091-2008: PDF in English (MTT 1091-2008)

MT/T 1091-2008
ICS 73.020
D 14
Registration number: 26892-2010
Standard for exploration and evaluation of
hydrogeology, engineering geology and environment
geology in coal beds
Issued by: State Administration of Work Safety
Table of Contents
Foreword ... 4 
1 Scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 6 
4 General ... 8 
5 Hydrogeological exploration and evaluation ... 9 
5.1 Degree of work ... 9 
5.2 Classification of hydrogeological exploration types ... 9 
5.3 Problems to be identified for various types of filling deposits ... 11 
5.4 Principles and quantity of exploration project layout ... 13 
5.5 Hydrogeological survey and mapping ... 15 
5.6 Hydrogeological and geophysical prospecting ... 20 
5.7 Simple hydrological and geological observations of borehole ... 23 
5.8 Pumping test ... 25 
5.9 Dynamic observation and water sampling ... 33 
5.10 Estimate of mine yield water ... 37 
6 Engineering geological exploration and evaluation ... 38 
6.1 Exploration types ... 38 
6.2 Basic requirements ... 39 
6.3 Principles for project layout ... 41 
6.4 Technical requirements for exploration ... 42 
6.5 Engineering geological evaluation ... 46 
7 Environmental geological exploration and evaluation ... 47 
7.1 General requirements ... 47 
7.2 Environmental geological investigation ... 48 
7.3 Environmental geological assessment ... 50 
Appendix A (Normative) Grading of water-richness of aquifer ... 53 
Appendix B (Normative) Grading of structural planes ... 54 
Appendix C (Normative) Grading of rock and rock mass quality and rock mass
advantages ... 55 
Appendix D (Informative) Empirical formulas for the maximum height of fall
zone and water-conducting fracture zone ... 56 
Appendix E (Informative) Calculation formula of safe impervious thickness and
water yield coefficient ... 57 
Appendix F (Informative) Classification of rock mass structure ... 58 
Appendix G (Informative) Field identification of weathering degree of rock mass
... 64 
Appendix H (Informative) Indoor test items for rock (soil) samples ... 65 
Appendix I (Informative) Basic work quantity of hydrogeological exploration 66 
Appendix J (Informative) Work quantity of engineering geological exploration
... 70 
Appendix K (Informative) River observation methods and tool making ... 71 
Appendix L (Informative) Common methods and formulas for estimating
underground mine water yield ... 77 
Standard for exploration and evaluation of
hydrogeology, engineering geology and environment
geology in coal beds
1 Scope
This standard specifies the basic guidelines for hydrogeological, engineering,
and environmental geological work in the geological exploration of coal
resources; it focuses on the technical requirements and working methods of the
This standard is applicable to the design and preparation, exploration and
construction, geological research, geological report preparation and review,
resource / reserve evaluation, mining right assessment, feasibility study at each
stage of geological exploration of coal resources.
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For the dated references, the subsequent
amendments (excluding corrections) or revisions do not apply to this Standard;
however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
GB 3838 Environmental quality standards for surface water
GB 12719 Exploration specification of hydrogeology and engineering
geology in mining areas
GB/T 14158 Survey code for regional hydrogeology, engineering geology
and environmental geology
GB/T 14848 Quality standard for ground water
GB 50027 Standard for hydrogeological investigation of water-supply
DZ/T 0080 Specifications for geophysical logging of coal
DZ/T 0215 Specifications for coal, peat exploration
5 Hydrogeological exploration and evaluation
5.1 Degree of work
Pre-exploration stage: Hydrogeological work is generally not carried out.
General exploration stage: Roughly understand the hydrogeological conditions
of the exploration area. Evaluate the economic significance of coal resources
and the possibility of development and construction.
Detailed investigation stage: Basically, identify the hydrogeological conditions
of the exploration area, evaluate the hydrogeological conditions that may affect
the development and construction of the mining area, provide a basis for the
overall development planning of the mining area.
Exploration stage: Detailed identification of the hydrological and geological
conditions of the mine field, evaluation of the mine water-filling factors,
budgeting of water yield at the pre-mined mining area, prediction of the
possibility and location of water yield during the mining process, comment on
possible changes in hydrogeological conditions after mining, evaluation of the
utilization possibility and approach of mining water, provide geological data for
the feasibility study and preliminary design of the mine construction.
5.2 Classification of hydrogeological exploration types
5.2.1 Well engineering coal mine According to the characteristics of the water-containing space of the
directly filling aquifer, the hydrogeological exploration of the coal bed is divided
into three categories:
a) The first category, ore deposits dominated by loose pore aquifers, which
are called pore-filled ore deposits;
b) The second category, ore deposits dominated by clastic rock aquifers,
which are called fissure filling deposits;
c) The third category, ore deposits dominated by carbonate karst aquifers,
which are called karst filling deposits. It is further divided into two sub-
types according to their filling methods:
1) The first sub-category, karst filling deposits dominated by water yield
from roof;
b) The unit water yield of directly filled aquifer is q < 1.0 L / (s·m), without
strong water-rich rock formations that are difficult to drain. Type II has medium hydrogeological conditions and easy to dry out:
a) The unit water yield of directly filled aquifer is 1.0 g / (s·m) ≤ q ≤ 10 L /
(s·m), the aquifer is weak in water-richness;
b) The unit water yield of directly filled aquifer is 10.0 L / (s·m) < q ≤ 20.0 L
/ (s·m), but the recharge source is lacking. Type III deposits have complicated hydrogeological conditions and
difficult to dry out:
a) The unit water yield of directly filled aquifer is q > 10.0 L / (s·m), there is
a large surface water body nearby and it is hydraulically connected to
groundwater; or although the recharge conditions are not good, q > 20.0
L / (s·m);
b) Open-air direct filling aquifers are thick, widely distributed, has strong
water-richness, which are prone to engineering geological problems such
as quicksand and difficult to dry out.
5.3 Problems to be identified for various types of filling
5.3.1 Pore-filled ore deposits
It shall focus on identifying the types of aquifers, distribution, lithology, thickness,
depth, structure, grain size, roundness, sortability, cementation degree, water-
richness, permeability, changes; identify the spatial distribution of quicksand
layers and characteristics, the combined relationship of aquifers (water barriers),
the hydraulic connection between aquifers, aquifers and weakly permeable
layers, and surface water; evaluate the dredging conditions of quicksand layers
and the effects of precipitation and surface water on mining of deposit.
5.3.2 Fissure-filed deposits
It shall emphatically investigate the thickness, depth, fissure properties, scale,
development degree, distribution rules, filling conditions and water-richness of
fractured aquifers; depth and weathering degree of rock weathering zone; the
nature, shape and scale of tectonic fracture zone and its hydraulic connection
with aquifers and surface water; the combined characteristics and proportion of
fractured aquifers and their relative aquifers.
damage of the fault structure on the integrity of floor; analyze and demonstrate
the segment which may produce lots of heaving floor and water yield.
5.4 Principles and quantity of exploration project layout
5.4.1 Layout principles of exploration project Hydrogeological exploration in the exploration area (well) shall be
carried out in combination with geological exploration. Hydrogeological
exploration work shall, based on the study of geological and regional
hydrogeological conditions, consider the thickness of aquifers, water-richness,
water conductivity, recharge and drainage conditions, the way to fill the mine as
a whole for investigation and research. For large water mining areas with
complex hydrogeological conditions (well-fields that flood more than 100000 m3
every day and night), the scope of work should be expanded to a complete
hydrological unit. The hydrogeological exploration must be based on the type of coal mine
hydrogeology and the specific conditions of the exploration area. It shall clarify
the issues that shall be focused on in this work, comprehensively use various
exploration techniques (including drilling simple hydrogeology-engineering
geological observation, hydrogeological survey and mapping, hydrogeological
exploration, hydrogeological drilling, pumping test, long-term observation and
sampling, other effective means) according to local conditions. In general, dynamic observation shall be carried out for various filling
deposits. Large water well fields (mining areas) with complex hydrogeological
conditions shall establish a long-term observation network for groundwater
dynamics. Pumping test drilling during the exploration stage shall, based on the
needs of the mine construction, be arranged in the initial mining area or in the
early mining area, close to the segment wherein the direct filling aquifer is
strong in water-richness and the fracture is well developed or close to the
recharge boundary. Pumping tests for groups of wells (interference well) with large flow rates
and large drop depths shall be arranged in strong water-richness segments
under the conditions that the natural flow field of groundwater has been
controlled. The layout of the observation holes shall control different boundary
conditions, incoming water directions, strong runoff zones, each runoff zoning,
pay attention to regional control. The pumping test of the fault zone shall, based on the development of
the fault structure and the hydrogeological characteristics of the well field
5.5 Hydrogeological survey and mapping
Hydrogeological survey and mapping is divided into region and exploration
areas. The scope of regional hydrogeological survey and mapping shall include
a complete hydrogeological unit, focusing on identifying regional groundwater
recharge, runoff, drainage conditions. Mining areas with simple hydrogeological
conditions may not require regional hydrogeological survey and mapping.
Hydrogeological survey and mapping of the mining area shall include the scope
of the potential impact of the dredging of the deposit and the boundary of the
recharge; the focus shall be on identifying the water-filling factors of the deposit
and the hydrogeological boundary of the mining area. Regional hydrogeological
survey and mapping is performed in accordance with GB/T 14158.
5.5.1 General requirements The scale of hydrogeological survey and mapping shall be determined
according to the stage of coal resource exploration and the complexity of
hydrogeological conditions. Generally, it is 1:50000 to 1:25000 in the pre-
exploration stage, general exploration stage, detailed exploration stage;
1:10000 to 1:5000 in the exploration stage. Hydrogeological survey and mapping shall be based on the
comprehensive collection of hydrological and meteorological data over the
years in the mining area and adjacent areas, to carry out the following
hydrogeological survey and mapping work:
a) Topographic features of the mining area, genetic types, lithological
characteristics and distribution of Quaternary sediments;
b) The number of layers of aquifers (water barriers), lithology, thickness,
occurrence, distribution range; the development of aquifer cracks, karst
caves, water-richness, water resistance property of water barriers;
c) Groundwater recharge, runoff, drainage conditions, physical properties
and chemical composition of groundwater, the hydraulic connections
between aquifers and with surface water, delineation of hydrogeological
boundaries of the mining area;
d) The elevation, stratum, lithology, way of exposure of springs and wells; the
measured flow, water level, water temperature, physical and chemical
properties of water, their dynamic changes;
e) The distribution of surface water, the elevation of flat water level and flood
level, the extent and duration of flood inundation, the depth, area and
storage capacity of surface water (such as reservoirs, ponds, etc.) that
have an impact on mining;
extremely developed and prone to water leakage, it shall conduct statistics of
the fissure rate; for fissure filling deposits which use where atmospheric
precipitation and old well water as the main recharge sources, it shall collect
the detailed data of the rainfall and rainfall intensity, pay attention to investigate
the lithology, mechanical properties, groundwater level elevation of the coal
seam’s roof cover, whether there is a thick plastic aquifer cover (such as clay,
kaolin, mudstone), the development of surface vegetation, the size of the slope
angle, the cut degree of the ditch and its direction, delineate the catchment area
and direct permeability zone and permeability of the mining area. Use the
method of equilibrium observation of small watersheds to determine the
atmospheric precipitation’s infiltration coefficient, carry out detailed
investigation of the development degree of the ground subsidence fissure and
the distribution of spring water and its water quality changes in the old well
mining area. The karst-filling ore deposit shall focus on investigating the various
morphology and geomorphology of karst, ascertaining the relationship between
karst development and factors such as lithology and structure, as well as the
distribution of karst in space, filling degree, water-richness and changes. The
karst filling deposits mainly composed of karst gaps and karst caves shall be
investigated for the lithology, structure, thickness of the overlying loose layer,
or the thickness, weathering degree, and physical properties of the overlying
rock weathering layer. Analyze the possibility of water yield, sand collapse,
ground subsidence, degree of subsidence, distribution range and impact on pit
water filling under neglected drainage conditions. For layered karst filling
deposits, it shall also investigate the distribution of relative aquifers and weak
5.5.2 Working methods Before the survey and mapping work is carried out, it shall collect and
study the past data of the exploration area and adjacent areas in detail, carry
out site exploration, compare the design document according to the tasks in the
exploration stage. The design document shall explain the purpose and task of
survey and mapping, the scope of work, the requirements of the degree of work,
the main working methods, the workload, the time and measures to complete
the survey and mapping work. The design document can only work after being
approved by the relevant superior or organization. After entering the exploration area, first select the sections with good
outcrop conditions and hydrogeological significance, measure the
hydrogeological reference profile, study the stratigraphic sequence, contact
relationship, and aquifer level, lithology, thickness, water content, karst and
fissure development, describe the groundwater outcrop point. The observation route of hydrogeological survey and mapping shall be The use of the geophysical prospecting method may detect the following
a) The thickness of the overburden layer, the spatial location of the hidden
ancient river bed and the buried alluvial fan;
b) The lack of "skylights" and the thickness and water-richness of the gravel
layer in the clay layer at the bottom of the Cenozoic;
c) The occurrence, spatial location and water-richness of geological
structures such as faults, subsidence columns, fissure zones, rock veins;
d) Aquifers on the roof and floor of coal seams and the water-richness;
e) The spatial location of the old empty area and the situation of standing
f) The interface and distribution range of groundwater soluble solids, salt
water, and freshwater;
g) The location of underground rivers and the distribution of hidden karsts;
h) The lower burial depth of the permafrost;
i) Groundwater level, flow direction and infiltration rate. The arrangement of geophysical prospecting work, the determination of
parameters, the number of inspection points and the repeated measurement
errors shall comply with the provisions of MT/T 897 and MT/T 898. Hydrological drilling shall be carried out for hydrological logging. It may
carry out flow logging and ultrasonic imaging in areas where conditions permit,
combining with the core drilling to divide the aquifer and water-impermeable
layers, to provide the basis for obtaining relevant parameters. For the geophysical prospecting data, comprehensive analysis shall be
made in combination with the geological characteristics of the deposit and
hydrogeological conditions, to propose the hydrogeological results.
5.6.2 Working methods Surface geophysical prospecting In the hydrogeological exploration, the surface geophysical
prospecting methods mainly include the resistivity method, natural electric field
method, charging method, frequency sounding method, induced polarization
method, magneto-telluric method, seismic method.
corresponding comprehensive results drawings.
5.7 Simple hydrological and geological observations of
5.7.1 General requirements The simple hydrogeological observation of borehole is to use geological
drilling observations to record data related to hydrogeology. The results are not
only an important basis for studying and evaluating the hydrogeological
conditions in the exploration area, but also the basis for rationally laying out
specialized hydrogeological boreholes. Boreholes for simple hydrogeological observations shall observe and
record in detail the layer and depth where the phenomena such as water surge
(leak), block loss, hole collapse, diameter reduction (expansion), gas escape,
sand yield, drill drop, abnormal water temperature, etc. occur during drilling;
measure the amount of yield (leaking) water; if necessary, it shall measure the
approximate stable water level and perform a simple discharge (injection) water
test. Describe the core lithology, constructional structure, fracture properties,
density, aquifer thickness, depth, weathering degree and depth of rock, karst
form, size, filling condition, development depth, statistics of fracture rate, karst
rate. The drilling of a single aquifer (group) shall determine the approximate
stable water level of the final borehole. According to the specific hydrogeological conditions of the exploration
area, when selecting the observation interval or observation content, it shall be
proposed in the exploration design and specified in the borehole design
(technical instruction). For boreholes that requires consumption observation, the circulation
system of flushing fluid shall comply with the drilling regulations; it shall conduct
the inspection and acceptance before drilling, to guarantee the quality of
observation results. When leakage is found and needs to be blocked during the drilling
process, it shall make detailed records for the depth of the starting and
stoppage and the method, material, time, and effect.
5.7.2 Observation methods
a) Observation once every 1 h, no change in water level for 2 consecutive
b) The water level changes in a single direction, the water level difference
within 1 h does not exceed 5 cm; it has been continuously observed for 3
c) The water level changes in a zigzag manner, the water level difference
within 1 h does not exceed 10 cm; it has been continuously observed for
3 h;
d) Although the above requirements are not met, the total observation time
has exceeded 24 hours.
5.7.3 Data arrangement The original records of the simple hydrological and geological
observations of the borehole shall be timely and true, which shall not be
recorded afterwards. The observations must be complete and the records must
be clear and not altered. The results of simple hydrological and geological observations of
boreholes shall be arranged in time; the following data shall be provided:
a) Raw records of simple hydrogeological observations of boreholes;
b) Simple hydrogeological histogram of boreholes;
c) Statistical table of simple hydrogeological observations of boreholes. According to the hydrogeological conditions of the exploration area, the
necessary analysis maps are to be prepared as follows:
a) Zoning (segmentation) map of main aquifer’s consumption;
b) Change of thickness of main impervious rock formations;
c) Aquifer contour map.
5.8 Pumping test
5.8.1 General requirements Pumping test is an important means for geological exploration of coal
resources. Its purpose is to study the important hydrogeological characteristics
of aquifers, obtain the aquifer's hydrogeological parameters, evaluate the
aquifer's water-richness, provide data for estimating the water yield from the
make a formal record. The water-stop inspection is performed before and after
the borehole is swept by the water-stop closure. The change of water level in
the pipe shall be less than 2 cm/h and maintained continuously for 3 hours. If the water pumped out of the borehole by the pumping test is likely to
seep into the aquifer again, measures must be taken to prevent leakage. The filter shall be selected according to the lithology, crushing degree
and particle composition of the aquifer. The pores on the filter shall be evenly
distributed; the porosity is generally not less than 20%. Where a wound or
bandaged filter is used, metal ribs shall be welded on the outer wall. The rib
spacing selection shall be based on the principle that the filter screen does not
contact the filter pipe. The work design document must reach the machine crew before
drilling construction; it shall explain to the construction crew the quality
requirements for construction, principles of pumping tests, recording methods
and precautions. Before the pumping test, it shall thoroughly check the installation
quality of the pumping equipment, various test instruments and tools for
measuring water level, water volume, and water temperature, as well as the
preparation of the original record form. The pumping test method is divided into two types: stable flow and
unsteady flow, which can be selected according to the generalized
hydrogeological model and hydrogeological parameter calculation
requirements. After the end of the pumping test, acceptance ratings shall be made in
accordance with the current quality standards in a timely manner.
5.8.2 Stable flow pumping test Test pumping Test pumping shall be carried out before formal pumping. Before the
test pumping, the pumping layer (segment) shall be repeatedly pumped until
the water from the borehole is clear and free of sediment. When washing the
boreholes in the loose layer, pay attention to observe and record the particle
size and volume of the washed-out sand, as well as the time and flow of the
water from turbid to clear. The test pumping shall be subjected to a maximum water level drop,
to preliminarily understand the relationship between the water level reduction
value and the amount of yield, in order to reasonably select the water level drop
during formal pumping. All data on the test pumping process must be officially
and the interruption time does not exceed 1 h, the pumping time before the
interruption can still be counted into the extension time, otherwise it will be void.
During the interruption of pumping time, it shall follow the requirements for
observing stable (static) water level to observe the water level (including the
observation hole), until the pumping is resumed. The measurement of water temperature and air temperature should
be observed at the same time every 2 h ~ 4 h during the pumping process. The
accuracy requirement is 0.5 °C. When abnormal water temperature is found,
well temperature shall be measured after pumping.
When measuring temperature, the thermometer shall be placed in a place
where the air is unobstructed and shaded. It is strictly prohibited to place it in
direct sunlight and other places where the temperature changes. During the pumping process, it must draw the Q = j (S) and q = f (S)
curves at any time, in order to find and correct errors in pumping in time. Water samples shall be taken according to the design requirements
before the end of the last depth drop. Relative error requirements for fluctuations in water level and flow
during stable time When the water level’s drop depth is greater than 5 m, the relative
error of the main hole’s water level fluctuation is not greater than 1%; when it is
less than 5 m, the change of the water level of the main hole is less than 5 cm.
The change of the water level of the observation hole is less than 2 cm. When
the burial depth of the water level is greater than 100 m, it can be appropriately
relaxed as appropriate. Relative error of flow fluctuation: q ≥ 0.01 L / (s·m), not more than
3%; q < 0.01 L / (s·m), not more than 5%. The calculation method of relative error of water level drop and flow
fluctuation during stable time is as follows:
Relative error of fluctuation = (maximum difference between observation and
average value / average value) x 100% Observation requirements for stationary and restored water levels Before and after the formal pumping, the pumping holes and
observation holes shall be subject to the observation of stationary and restored
water levels. At the beginning of restoring the observation of water level, it is
drop pumping. When pumping at a constant flow rate, the required change in
flow rate is generally not greater than 3%; when pumping at a fixed drop, the
water level’s change rate is generally not more than 1%. Unsteady flow
pumping shall generally use submersible pumps or deep well pumps. For the water level drop of the unsteady flow pumping test, the
equipment capacity shall be used to perform one maximum drop, which is
generally not less than 9 m. If the amount of yield water is greater than 140
m3/h, the minimum drop depth shall not be less than 3 m when the drop cannot
meet the above requirements due to conditions. When the water column above
the bottom of the aquifer is less than 10 m, the maximum drop of the water level
shall exceed 1/2 of the height of the water column. Observation of water level and flow should be performed according to
the time sequence of 1, 2, 3, 4, 6, 8, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, 120
minutes after the start of pumping. The observation can be performed once
every 30 minutes afterwards until the end. The observation hole’s water level is
observed simultaneously with the main hole. The duration of pumping shall be determined according to the purpose
of the test by referring to the water level drop - time semi-logarithmic curve S
(or h)-lgt form. When the curve appears a......
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