Table of Content

20 August 2018, Volume 24 Issue 4

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The Petrogenesis and Mineralization of the Laiziling Greisen,Xianghualing District, Hunan Province, South China

WANG Zhengjun, XIE Lei*, WANG Rucheng, ZHU Jinchu, CHE Xudong, ZHAO Xu

2018, 24(4):  467. 

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The Laiziling granitic pluton comprises three rock phases with a pronounced vertical lithological zonation, granite, greisen
and pegmatite from base to top. Greisen from the Laiziling granitic pluton is characterized by its huge thickness, micas belonging to the
zinnwaldite, high abundance of topaz and high W-Sn-Nb-Ta concentration. Petrological, geochemical and mineralogical studies have
been carried out on the Laiziling greisen. It is concluded that the Laiziling greisen is a peraluminous rock with high silicon content, low
content of total alkali (3-4.3 wt%), Zr/Hf (~8) and Nb/Ta (~1.7) ratios, and enrichment of the volatiles. Micas in the Laiziling greisen
are classified into zinnwaldite, and LA-ICP-MS analysis results indicate they have high content of Nb (~74×10-6), Ta (~66×10-6), W
(~23×10-6) and Sn (~75×10-6) concentrations. Zircons in the Laiziling greisen are commonly euhedral and homogeneous and contain
high HfO2 (~10 wt%) content, and Zr/Hf ratio as low as 5. The compositions of zircon display a successive change compared with those
from the Laiziling albite granite. These chemical characteristics of the greisen are similar to those of highly fractionated rare-metal
granites and pegmatites in the Nanling Range with similar fractionation degree. Columbite-group minerals, cassiterite and wolframiteare found in the Laiziling greisen, suggesting the obvious W-Sn-Nb-Ta mineralization. Both mineral textures and chemical
compositions indicate these oxide minerals formed in the magmatic stage. Granitic magma contains high concentrations of volatiles (Li
and F), which play a very important role in the petrogenesis and the rare-metal mineralization of greisen. Li and F were incorporated
into the Li-F mica and topaz and rare metal mineralization formed in the late stage of magmatism enriched in large amount of fluid.
Consequently, greisen could probably be the product by the strong fractionation and fluid activity after the albite granite formed in the
same granitic chamber. The results should open a new window for understanding the petrogenesis and rare-metal mineralization in the
granitic magmatic-hydrothermal system.

Genesis of Siderite Precipitated in the Lopingian Coal Measures in Zhijin Mining Area, Western Guizhou

ZHANG Tao, SHEN Yulin*, LI Zhuangfu, JIN Jun, ZONG Yi, LIU Jinbang, ZHENG Jun

2018, 24(4):  481. 

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Siderite with a wide spectrum of micro morphologies has been found in the Longtan Formation of the Lopingian coal-bearing
measures in Zhijin Mining area, western Guizhou. The origin and phase evolution of siderite are discussed based on thin section
observations and trace elements analysis. The study suggests that siderite with various micro morphologies could be divided into three
diagenetic generation products, comprising siderite colloidal aggregates precipitated during the first generation, poorly zoned
spherulites developed during the second generation, and perfectly zoned sphaerosiderites as well as rhombohedra precipitated during
the third generation. Siderite colloidal aggregates were crystallized rapidly when the concentration of metallogenic components (Fe2 +
and CO32-) reached their supersaturation stage. Poorly zoned spherulites were formed by adhering metallogenic materials to siderite
colloidal particles precipitated during the first generation. Perfectly zoned sphaerosiderites were developed by the syntaxial and
continuous overgrowth of numerous radiating linear crystals surrounding the spherulites developed during the second generation.Moreover, the pulse-like transgression during the Late Permian might have acted as an external driving factor which would lead to the
reciprocating cycle of siderite between crystalline equilibrium state and non-equilibrium state, and finally the concentric zonation
structure was formed. The formation of perfectly zoned sidetite rhombohedra might have resulted from changes of growth patterns from
the radiating growth to the rhombohedral growth caused by variations of metallogenic conditions.

Characteristics of Fluid Inclusions and Stable Isotopes of the Hydrothermal Vein-type Deposits in Southern Great Xing’an Range, China: Implications for the Genesis of the Deposits

WANG Chengyang, WANG Keyong, LIU Guanghu*, FU Lijuan, QUAN Hongyan

2018, 24(4):  491. 

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Several hydrothermal vein-type deposits, including Dajing Sn-Cu poly-metallic deposit, Shuangjianzishan Ag polymetallic
deposit, Bujinhei Pb-Zn deposit, Bairendaba Ag-Pb-Zn deposit and Weilasituo Sn-Cu polymetallic deposit, were developed in the
southern Great Xing’an Range. In order to further understand the characteristics and differences of the ore-forming fluids and
ore-forming materials from the hydrothermal vein-type deposits in this area, we carried out studies of fluid inclusions, Laser Roman,
and H-O-S isotopes on the basis of field geological investigations. The results show that:（1）Ore-forming fluids of Shuangjianshan
deposit belong to simple brine system, ore-forming fluids of Bujinhei and Weilasituo deposit belong to carbonaceous-rich brine system,and the initial ore forming fluids of Dajing deposit belong to daughter mineral bearing fluids, respectively;（2）Ore-forming fluids of
early stage from Dajin, Bujinhei, Bairendaba and Weilasituo deposit were mainly derived from magmatic fluids, while the fluids were
affected by meteoric water and organic matters.（3）The δ34S values of different hydrothermal vein-type deposits change around 0‰,
and show the characteristics of deep source magma. Different magmatic sources and the involvement of the strata sulfur during
mineralization may be the main cause for the differences of sulfur isotope composition among deposits. Generally, there exist obvious
differences in terms of material sources and fluid evolution among different hydrothermal vein deposits in southern Great Xing’an
Range, which reflects the diversity and complexity of the Mesozoic hydrothermal mineralization in-this area.

Geological Characteristics and Rb-Sr Dating of Sphalerites from the Shengtianping Zinc Deposit in Southeastern Yangtze Block and Its Geological Significance

CAO Liang，LIANG Yuming，DUAN Qifa，LIU Chongpeng，ZHOU Yun

2018, 24(4):  504. 

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Shengtianping zinc deposit is located in Xuefengshan region, which is at the southeastern part of Yangtze Block. It is a
medium-size zinc deposit that occurs in the Doushantuo Formation in western Hunan Province. In this study, Rb, Sr isotope analysis
were carried out on the main metallogenic period of sphalerite using the isotopic dilution method. Rb-Sr analyses yield an isochron age
of 490 Ma and the initial strontium isotopic composition of 87Sr/86Sr is 0.71235. The isochron age represents the timing of the main
mineralization stage of the deposit, indicating that the deposit was formed in the late Cambrian and the mineralization occurred in the
middle Caledonian. The characteristics of the sphalerite initial strontium isotope ratios reflect the far-field effect of the collisions of
surrounding blocks, which provided a driving force for the hydrothermal mineralization, and the Caledonian tectonism plays an
important role in the formation of the Shengtianping zinc deposit. The Shengtianping zinc deposit is strictly strata-bound, and the
deposit belongs to the sedimentary-transformation type of strata-bound ore deposit.

The Lithospheric Structures Beneath the Au Deposits in the South Ailaoshan Shear Zone from Receiver Functions: Implications for Lithospheric Thinning and the Magma Channel

YU Dayong, WANG Pan*

2018, 24(4):  516. 

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The Indo-Tibetan collision created the huge amounts of ore deposits in the Tibetan Plateau and around areas. Though these
ore deposits have been well studied, it is still a challenge to link the reserve, the migration and the reserve together for an integrated
analysis of the mineralization mechanism. Especially, it is still a gap to analyze the origin of the ore-forming materials in the
crust-mantle scale. Thus, we use conversional seismic waves (i.e. receiver function technique) to study the lithospheric structures
beneath the Daping-Chang’an Au deposits, which present strong evidence for mantle-induced origin, in the south segment of the
Ailaoshan shear zone, southeastern margin of the Tibetan Plateau. We obtained a vertical section across the Au deposits region. The
crust-mantle boundary (Moho) beneath the Au deposits is at 30-40 km depth while presents a clear sharp depression (~3-5 km) and
complex waveforms. The lithosphere-asthenosphere boundary (LAB) on the section is at 60-80 km depth, constraining the thickness of
the lithosphere after the strong thinning. The thinnest lithosphere is beneath the central Simao block and is above a low-velocity zone in 
the uppermost mantle from tomography. As well as the lateral discontinuity at the Moho beneath the deposits, the LAB beneath the
deposits presents a significant lateral discontinuity, indicating lithospheric scale discontinuity. The lateral discontinuities at both the
Moho and the LAB imply the magma channel, which could facilitate a quick migration of the magma from the asthenosphere to surface.
We thought that the lithospheric structure beneath the Daping-Chang’an Au deposits supports the model of the subduction-induced
mantle origin of the ore-forming materials. However, we thought that the shear of the Ailaoshan shear zone dominated the inferred
lithospheric magma channel and that the subduction-induced upwelling of the mantle materials presented memorial contributions to
the formation of the magma channel.

Zircon U-Pb Ages of the Late Jurassic Volcanic Rocks from the Zenong Group in the North of Zabuyechaka Area, Tibet and Its Geological Significances

YE Chunlin, HUANG Baixin, WANG Yi, HOU Yunling, JIA Xiaochuan, YANG Xuejun

2018, 24(4):  525. 

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The Late Mesozoic tectonic evolution models of the Gangdese belt in Tibet remain controversial. We present here the field
observations and zircon U-Pb ages of the volcanic rocks from the Zabuyechaka in the Mid-Gangdese belt. Zircon U-Pb dating results
suggest that the volcanic rocks of the Zenong Group were formed during 154.2-142.1 Ma. This study first obtain the Late Jurassic ages
of the Zenong Group (154 Ma), which is approximately 24 m.y. older than previously published data. The data from this study, and
combined with previously published data on Mesozoic volcanic rocks in the whole Gangdese belt show obviously northward younger
trends. It suggests that the Early Jurassic arc volcanic rocks in the south Gangdese belt were associated with the subduction of the
Neo-Tethys oceanic plate, and the Middle-Early Cretaceous arc volcanic rocks in the north Gangdese belt were related to the
subduction of the Bangonghu-Nujiang oceanic plate, and the Late Jurassic to Early Cretaceous arc volcanic rocks in the middle
Gangdese belt were jointly affected by the northward subduction of the Neo-Tethys and the southward subduction of the
Bangonghu-Nujiang oceanic plates. This study provides new evidence for the Late Mesozoic tectonic evolution of the Gangdese belt.

Progresses on Mercury Isotopic Geochemistry of Coal

LI Chunhui,LIANG Handong*, CAO Qingyi, SHI Yunyun

2018, 24(4):  536. 

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Mercury is one of the widespread trace elements in coal. The large amount of coal consumption makes it as a main source of
global mercury pollution. Seven kinds of stable isotopes, both mass-dependent fractionation (MDF) and mass-independent fractionation
(MIF), and significant variations in isotopic composition of the involved coal samples, make Hg isotope an ideal way to assess sources of
Hg pollution. Mercury isotope studies of coals have made significant progress over the past twenty years, which can be summarized as
follows. Firstly, δ202Hg value and its distribution of coals from 11 countries were preliminarily researched, which from the basis of
identifying coal Hg pollution source. Secondly, MIF was found in coals, which was beneficial to do tracing studies with δ202Hg. Thirdly, δ 202Hg and Δ199Hg values in different areas and geologic periods were preliminary determined in our country. Further work may focus on
the following areas: Mercury isotope database of coals from different areas and geologic periods in the world should be supplemented,
revised and perfect. Mercury isotopes changes associated with the interactions between gas-water environment and coal mining residues
such as coal gangue and residual coal should not be neglected. Mercury isotopes of coal combustion products such as atmospheric fine
particulate matter (PM2.5) should be studied. Migration and transformation of the coal fire surface mercury is complex because partial
mercury on the surface may become secondary mercury release. This fractionation process of mercury isotope will no doubt make it
difficult to trace the pollution source with mercury isotope studies. In a word, the study of mercury and mercury isotopes of coal is
burgeoning.

Spatiotemporal Pattern of Earthquake Activities and Seismotectonics in Jiangsu and Adjacent Southern Yellow Sea Area

LI Xudong, LIU Shaowen *, WANG Li

2018, 24(4):  551. 

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Jiangsu Province and the adjacent Southern Yellow Sea area is one of the most economically developed regions in east
China, along with dense cities, large population and integrative infrastructures. This area is, unfortunately, vulnerable to earthquake
hazard threatening its socio-economic development. Historically a number of medium and strong magnitude earthquakes frequently
occur this area. The seismogenic mechanism for this area is not well understood. Here we collect all the historical and instrumental
earthquake data available in this area, to investigate the spatiotemporal pattern of the seismicity and its seismotectonics. We found that
the earthquakes are clustered and generally associated with several main active fault zones; the seismically quiescent period for this
area approximates to 60 years, and it is now still at the active phase. In addition, integrative geophysical analysis demonstrates that the
Wunansha Uplift and Southern Depression of the Jiangsu and Southern Yellow Sea areas, where the seismicity is comparatively
intensive, show prominent deep structure anomalies, suggesting a genetic link between the seismicity and deep structure. The westward
subduction of the Philippian Sea Plate and the far field effect of the Indo-Asia continental collision, along with the gravity potential
difference derived from the elevation contrast between the craton and shelf area, account for the driving force trigging the earthquake.
The results presented here not only promote our understanding of seismotectonics in this region but also have important significance for
earthquake hazard mitigation in the Jiangsu and Southern Yellow Sea area.

Influence of Basement Property on the Fracture Structure:A Case Study of the Qiongdongnan Basin

ZHANG Jiaxing, YIN Hongwei*, ZHU Jitian, XIONG Xiaofeng, WANG Wei, LI Changsheng,WU Zhenyun, LIU Shaowen

2018, 24(4):  563. 

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There are several factors influencing the formation of fracture system .In this paper, three scaled analog sandbox models
were constructed to simulate the tectonic evolution of fault in rift basin, to explore the tectonic evolution of Qiongdongnan basin during
the main fracture stage. According to the interpretation of 2D seismic section, the depression in eastern and western Qiongdongnan
Basin shows different tectonic forms. Model results showed that the evolution and development of adjacent depression is affected by the
position and direction of the fault-margin affects, and the basement property had a significant influence on the tectonic evolution. The
formation of graben structure is affected by pre-existing fault, the regional tectonic evolution formed horst without pre-existing fault. The
compound half-graben occur when the basement develop ductile deformation, and the shovel-like half-graben of structural style occur
when the basement develop brittle deformation. Based on the model results, it is proved that the basement property plays an important
role in developing different kinds of fault combination in the eastern and western Qiongdongnan Basin, which provide the paths for
studying the fracture system of hydrocarbon migration and accumulation.

Tectonic Evolution of the Tan-Lu Fault in the Cenozoic and Its Effect on Hydrocarbon Generation and Expulsion of Source Rocks: A Case Study of the Liaozhong Sag (Liaodong Bay Depression)

JIANG Ziwen, LUO Jinglan, WANG Simin*, HUA Xiaoli, NIU Xinjie, TIAN Ya, WANG Xiaolei, CUI Kai

2018, 24(4):  573. 

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The Tan-Lu fault zone is an important active fault zone in the Bohai Sea area, which controls the conditions of regional oil
and gas accumulation. Based on a case study in the Liaozhong sag of the Liaodong Bay Depression, the geometrical and evolutionary
characteristics of the Tan-Lu fault were studied by using 3D seismic data and the balanced section technique. Based on the results, the
influence of the strike-slip activity of the Tan-Lu fault on the development, distribution, evolution, generation and expulsion of source
rock was addressed. Results show that the tectonic evolution of the Liaodong Bay depression in the Cenozoic is divided into five stages
and three cycles. The strike-slip activity of the Tan-Lu fault staggers the source rocks developed in the early and synchronous stages,
changes the spatial distribution of source rock and hydrocarbon generation potential, and makes it beneficial to form reducing
environments and develop source rocks with higher hydrocarbon generation potential. The strike-slip activity increases the geothermal
gradient and the geothermal heat flow near the fault zone, which is conducive to reducing the hydrocarbon generation threshold.
Different parts of the Tan-Lu fault vary in activities in periods, and they act as close or open channels for hydrocarbon migration. The
Tan-Lu fault strike-slip activity from the late Dongying and early Minghuazhen stages to the present has a good matching with the main
hydrocarbon generation and accumulation periods. It is suggested that the strike-slip activity of the Tan-Lu fault forms a
“towed-pattern” of the hydrocarbon generation and expulsion. As a result, the traps with relatively poor source rock conditions may
also have exploration value, which broadens the ideas of oil and gas exploration.

Quantitative Evaluation of Micro-Pore and Throat Characteristics in Low-Ultra Low Permeability Sandstone Reservoirs by Using Constant-Rate Mercury Injection Technique: A Case Study of the Ed3 in the Steep Slope Zone (Shijiutuo Uplift)

WAN Lin，WANG Qingbin，DAI Liming，TANG Guomin，PENG Qin

2018, 24(4):  584. 

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The low-ultra low permeability sandstones in the glutentite reservoirs play an important role in the oil migration and
accumulation. To understand the micro-pore and throat distribution and contribution of different sizes of pores and throats to physical
property of tight sandstones with different permeability grades, a case study was conducted in the fan delta glutenite reservoirs of the
steep slope zone of the Shijiutuo uplift by using constant-rate mercury injection technique. Results show that low-ultra low permeability
sandstones are characterized by medium pore size, small throat radius and large pore throat ratio compared with conventional
sandstones. Permeability is affected by pore and throat radius obviously, and the number and distribution of the throat with large radius
are key to affect the seepage capacity of reservoir. The pore-controlled mercury entry zone is the most effective and important space for
fluid flow. The higher the permeability is, the larger the throat radius of the pore master zone is. In the pore-throat transition mercury
zone, mercury is mainly combined by pore and throat. With the decreasing of throat radius, fine throat gradually becomes the main
space for fluid storage and flow. The contribution of permeability in the main control area is also very low. The micro-and fine-throat are
throat radius. With the increasing of permeability, the critical throat radius of the permeability of the low-ultra low permeability
sandstones increases from 1-2 μm to 3-4 μm. Therefore, based on the constant-rate mercury injection technique, quantitative
characterization of micro-pore and throat of low and ultra low permeability sandstones fills the research gap in the Bohai area. This
would be helpful to the realization of comprehensive and accurate evaluation of such reservoirs.

Advances in Multiple-point Geostatistics Modeling

CHEN Huanqing, LI Wenqing, HONG Yao

2018, 24(4):  593. 

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Focusing on the significance of geological modeling in fine reservoir description, this study introduces the present situation
of multi-point geological statistics modeling and its differences with traditional geological modeling methods. Taking a steam flooding
area in West depression of Liaohe Basin as an example, we analyzed the basics of multipoint geostatistics modeling, the establishment
of the training images, the advantages of multipoint geostatistics modeling compared with the traditional geological modeling. It is
pointed out that geostatistics is better than other traditional modeling methods in the reservoir prediction of cross-wells. Based on the
literature review and the authors investigations, this paper discusses the existing problems and future research directions of multi-point
geostatistics modeling. The future research in geological statistics modeling mainly includes the geological genesis analysis in order to
gain training images, and the algorithm to improve, perfect, and expand the application field of multiple-point geostatistics, etc.

Automatic Fourier-descriptor-based Generation of Paticle Shape of Sandy Soil

FANG Hao, ZHANG Wei*, XIAO Rui, SHI Bin, LIU Yan, ZHAO Chunfa

2018, 24(4):  604. 

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Particle shape is one of the main factors affecting the compactness, mechanical and seepage properties of sandy soils.
Fourier description is one of the mathematical methods effectively characterizing the grain shape. Based on the Fourier coefficient and
grain mean radius, we define the Fourier descriptor Dn. Employ Fourier descriptor D2, D3, D8 and, the logarithmic linear combination of
D3 and D8, we develop a simplified algorithm to automatically generate complicated soil grain shapes. The grain shape is controlled by
both Fourier descriptor Dn and phase angle δn series. The correlation between Fourier descriptors D2, D3, D8 and the grain geometrical
parameters. The results show that the length-width ratio a is positively correlated to D2, circularity C is negatively correlated to D2 and
D8, roundness R is strongly negatively correlated to D8, sphericity S is strongly negatively correlated to both D2 and D3 and, regulation Re
is negatively correlated to D8 and, negatively correlated to D3 when D8 equals to 0. Using the typical grains in the binary images of
Nanjing silty sand, obtained by micro-CT scanning, as samples, the shape similarity is calculated based on Pearson correlation
criterion. The correlation coefficient is higher than 0.94, suggesting that the algorithm possess the relatively high characterization
accuracy. The algorithm can be used to automatically generate massive practical sand grains in the two-dimensional numerical
simulation.

Experimental Investigation on Shear Strength of Fiber Reinforced Municipal Sludge

WANG Hongsheng, WANG Peng, TANG Chaosheng*, LIU Changli, SHI Bin

2018, 24(4):  613. 

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With the high development of society, municipal sludge production increased year by year. It has important significance for
improving the urban ecological environment and economic sustainable development to efficiently dispose this kind of municipal sludge.
Sludge usually has high moisture content, More importantly, it has a very high fraction of organic and fine particles with the high
viscosity, and it is not only low efficient to reduce the total volume through mechanical dehydration but has a low strength of the sludge
after dehydration, which is easy to cause the landfill pile skid, instability and other accidents. Fiber-reinforcement is a newly developed
soil improvement technology. in order to study the effect of fiber reinforcement on sludge sheer strength properties, a series of shear
strength tests were conducted on sludge with different fiber contents (0, 0.05, 0.1, 0.2, 0.4 and 0.8%) under different consolidation
pressure （50, 100, 200 and 400 kPa） . The effect of fiber addition on the moisture content, dry density and shear strength under
different consolidation pressure were analyzed. The results showed that under different consolidation pressure, the water content of the
sludge decreased firstly and then increased with the increase of the fiber content after the consolidation, while the dry density change
trend is opposite, and the experimental determination of the optimal dosage of fiber content is 0.1%. The shear strength of sludge is
increased with the increase of the content of the fiber after consolidation, fiber reinforcement effect on sludge are very effective in the
shear strength, and the reinforcement effect is the most significant under the 100 kPa. The strain hardening tendency is more
 significant with the increase of fiber content in the late shear failure process

Laboratory Study on Soil Residual Strength of Slip Zone of A Landslide in the Xiangjiaba Reservoir Area

DONG Wenping, DAI Fuchu, ZHANG Hongying, HUANG Zhiquan

2018, 24(4):  619. 

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In order to study the effect of shear rate (less than 100 mm/min) and fine grains (less than 0.075 mm) content on residual
strength of the slip zone of a landslide in the Xiangjiaba reservoir area, ring shear tests were conducted on remolded slip zone soil using
the DTA-138 ring shear apparatus, the fine grains content and microstructure of slikensided surface of undisturbed samples and shear
surface of remolded samples were comparatively analyzed. It was found that the fine grains content obtained from undisturbed
slikensided surface are larger than that from the slip zone, and the fine grains content obtained from shear surface of remolded samples
are larger than that from area adjacent to the shear surface. With an increase of the rate of shear from 0.109 mm/min to 98 mm/min, the
residual strength stress ratios exhibit a concave pattern, ie. decrease at first and then increase with the lowest mobilized stress ratio at
the 1.09 mm/min (the lowest mobilized stress ratio of Rr-1#, Rr-4#, and Rr-5# remolded samples are 0.34, 0.42 and 0.39 respectively) .
The residual strength first increases and then decreases with increasing fine grains content, exhibiting a quadratic polynomial relation
with a critical value about 56%, and with increasing fine grains content, the range of variations in residual strength increases with
normal stress.