bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Ground Water on Blasting Construction of Adjacent Tunnel
Authors: Peizhe Shi , Yadong Xue , Mingliang Zhou , Yongyi Wang , Lining Wang
Published: November 2020

During the construction of a mountain tunnel, water-rich strata are often encountered. Current research on the influence of groundwater on the blasting construction of the adjacent tunnel is not in-depth enough. Based on the Yingpanshan tunnel project of Huali Expressway in Yunnan Province, China, this paper analyzes multi-factor couplings such as blasting dynamic load, large-section excavation, groundwater and adjacent construction. An adjacent construction model with a size of 80×80×50m is established by COMSOL Multiphysics software. Considering the change of permeability and elastic modulus of the model, the influence of blasting construction on the adjacent construction is reflected by the vibration velocity of the existing tunnel lining. The results show that the impact of groundwater on the safety of the adjacent structure is mainly related to the permeability, and its influence degree increases with the water pressure. In the water-rich stratum with high permeability of rock mass, it is necessary to pay attention to the influence of groundwater on the safety of adjacent blasting construction.
An empirical strength criterion for deep rock incorporating the effect of fracture intensity using distinct element method
Authors: Jiang Mingjing , Liu Asen , Wang Huaning , Lu Guowen , Li Lei
Published: November 2020

Deep rock strength is one of the most important research areas in rock mechanics and engineering which is closely related to bearing capacity and stability of underground structures. Due to high ground stress, the mechanical behaviours of deep rock are different from those of shallow rock. In order to characterize deep rock strength precisely, a great number of rock strength criterions have been proposed over the past few decades to quantitatively describe the relationship between complex stress state and rock strength parameters. Some microscopic characteristics like fracture intensity(P32
) have received some attention. They are thought to have significant influences on the strength of deep rock. Currently, most of the constitutive models and strength criterions focused on the shallow rock and macro mechanical parameters, and they can not directly explain the relationship between the microscopic fracture characteristics and the strength of deep rock. In this research, the effects of fracture characteristics and confining pressure on deep rock strength were investigated using distinct element method(DEM). Firstly, an improved bond contact model incorporating rolling and twisting resistances was implemented in the rock numerical specimens, and the Smooth-Joint contact model was used for simulating fractures of rocks. The fracture length distributions in specimens were characterised by an exponent parameter a. Then numerical simulation of triaxial compression tests were carried out on numerical rock specimens under different confining pressures and P32
. The results show an approximate linear relationship between the maximum principal stress and P32
. Rock strength decreases with the increase of P32
, and it decreases rapidly at a higher confining pressure. Based on the results, a new empirical strength criterion is proposed. The criterion considers the nonlinear relationship between maximum principal stress and confining pressure of deep rock, additionally reveals the correlation between microscopic fracture characteristics and rock strength. In principle stress space, the corresponding failure envelopes projected onto the π-Plane showed a good agreement with DEM simulation results, which indicates a good applicability for the prediction of deep rock strength.
Micro-crack propagation and coalescence during time-dependent deformation of granite based on numerical manifold method
Authors: Yu Xian-yang , Xu Tao , Heap Michael J. , Baud Patrick , Heng Zhen
Published: November 2020

An understanding of influence of micro-cracks on time-dependent deformation in granite is of fundamental importance in many situations, such as nuclear waste storage facilities or the exploitation of geothermal resources. Time-dependent cracking is considered to be the main mechanism of brittle creep in granite. Creep strain rates are strongly influenced by the density of pre-existing defects that also exert a significant influence on rock physical properties. We introduce a new model that combines the subcritical crack growth (SCG) theory and the numerical manifold method (NMM) to link the local damage (using an exponential material softening law) caused by micro-crack propagation and the macroscopic creep deformation typically observed in granite specimens. In this model, each element contains a virtual micro-crack that can propagate sub-critically following Charles’ law. Once the virtual micro-crack length reaches a given value, it will convert to a real micro-crack, which can cut through adjacent elements, open, and slide according to the principle of NMM. We also investigated the influence of virtual micro-crack length, confining pressure and differential stress on creep behaviour. The fact that numerical simulations are in good agreement with experimental results shows that the NMM combined with the SCG theory is a suitable method for modelling the creep behaviour of rocks.
Impact of Mode I and Mode II Fractures on Fracture-Gas Permeability in Shale: An Experimental Study
Authors: Lu Yunhu , Chen Guanglei , Yang Shuai , Jin Yan , Li Ji , Xie Quan
Published: November 2020

The natural-fracture network and a large part of hydraulic fractures are poorly supported, and the conductivity of the natural-fracture network is highly sensitive to stress and strain during the production stage. In this work, we aimed to understand the impact of mode I (tensile) and mode II (shear) fractures on fracture-gas permeability as a function of effective stress in Long Ma Xi shale in the Dragon Horse Creek Group in Western China. Experimental results showed that the two-mode fracture tortuosity and width of shale were opposite those of sandstone. Our results implied that in Long Ma Xi shale, mode I fractures likely contributed significantly to early-stage high well productivity, with low effective stress, and mode II fractures may contribute to well productivity after the initial stage of gas production, with relatively high effective stress.
Effects of normal stiffness on the shear behaviors and acoustic emissions of rock joints
Authors: Wang Changsheng , Jiang Yujing , Luan Hengjie , Zhang Sunhao , Han Wei
Published: November 2020

In this study, direct shear tests were conducted on plaster joints under various boundary conditions. During shearing, the acoustic emission (AE) was measured by the PAC AE system. The damage of the asperities was evaluated based on the AE signals. The effects of the normal stiffness on the shear behavior and asperity damage were studied, and the corresponding AE characteristics were analyzed. The results show that the peak shear stress for rock joints under constant normal load boundary conditions is larger than that under the CNS boundary conditions. The shear dilation decreases as the normal stiffness increases. The AE signals are more active in the post-peak stage for the rock joints sheared under higher normal stiffness conditions. Both the AE count and AE energy rate increase with an increase in the normal stiffness. Thus, the total AE events increase with increasing normal stiffness.
Influence of stress amplitude on the dynamic characteristics of phyllite samples under triaxial multi-stage cyclic loading
Authors: Bie P F , Liu H X
Published: November 2020

The generation of a rockslide in an earthquake event is strongly dependent on the dynamic characteristics of the rock materials constituting the rock slope. In this study, phyllite samples were extracted from the Donghekou landslide area of Qingchuan County. The landslide occurred during the 2008 Wenchuan earthquake and the samples were made to undergo multi-stage cyclic loading and unloading tests under triaxial compression conditions. The confining pressure during the tests was 10 MPa, the loading frequency was 2 Hz, the loading waveform was sine wave, and 60 loading cycles were carried out at each level of stress. From the dynamic axial stress–strain curves, the effect of stress amplitude on the hysteresis loop area, the dynamic elastic modulus, the dynamic damping ratio, and the damping coefficient of the phyllite samples was analyzed. The results are as follows. (1) The strain–stress hysteresis loop area experienced a rapid increase as the stress amplitude exceeded a certain value, indicating that the rock samples have entered an accelerating crack propagation stage under high levels of cyclic loading. (2) As the stress amplitude increases, the dynamic elastic modulus, the dynamic damping ratio, and the damping coefficient of the rock sample followed a similar two-phase evolution law. There was a rapid reduction in the three parameters relative to the initial value in Phase I. Moreover, there was a minor change in Phase II. (3) The effect of the number of loading cycles number on dynamic elastic modulus and damping parameters was much more obvious under the lower levels of cyclic loading than under the higher levels.
Influence of Drying–Wetting Cycle of Acid Solution on the Mechanical Properties of Sandstone
Authors: Chen Z H , Chen W F , Tan Y S , Rong G
Published: November 2020

Ensuring the stability of reservoir slopes requires a comprehensive understanding of the mechanical properties of rocks after the drying–wetting cycles under acidic conditions. In this work, sandstone samples were selected and subjected to cyclic drying–wetting treatments with aqueous solutions of pH 7.0, 6.0, 4.0, and 2.0. The uniaxial compression tests and P-wave velocity measurement were carried out to evaluate the variations in the physico-mechanical properties of sandstones with different treatments. The results revealed that the internal structure of sandstones is softened by the drying–wetting cycles, which deteriorate their physico-mechanical properties. As the acidity of the aqueous solution increases, porosity and Poisson’s ratio show an increasing trend, while the strength characteristics, Young’s modulus, and P-wave velocity of sandstones present a decreasing trend. The physico-mechanical properties of sandstones significantly deteriorate from neutral to weakly acidic solutions; however, the deterioration becomes slower as the acidity continues to increase. Moreover, the physico-mechanical properties of sandstones are markedly reduced under strong acidic conditions.
Experimental research on the anisotropic properties of sandy slate
Authors: Wang Lehua , Tang Kaiyu , Li Jianlin , Xu Xiaoliang
Published: November 2020

In this study, the effect of joint on the anisotropy of a homogeneous, stiff, and intact sandy slate from a typical hydropower station is investigated by selecting and making jointed rock samples with jointed angles of 0°, 30°, 45°, 60°, and 90°. Accordingly, an acoustic measurement and a triaxial compression test are conducted on these jointed rock samples. The research results show that the joint angle significantly influences the rock mass anisotropy. In other words, the average value of the longitudinal wave velocity of the jointed rock samples is smaller than that of the intact rock. Furthermore, the value of the longitudinal wave velocity increases with the increase of the joint angle and is the largest when its spreading direction is in line with the joint inclination. The stress–strain curve, elastic modulus, peak strength, and failure mode of the joint rock samples are found to have anisotropic features. The failure stage occurs in samples with joint angles of 0°, 30°, and 90°. The stress–strain curve of the samples with joint angles of 45° and 60° tends to be horizontal. Meanwhile, the elastic modulus and the compression strength displayed a U-shaped distribution with an increase of the joint angle and the smallest value that belongs to samples with joint angles of 30° and 60°. The peak value ratio of the elastic modulus and the compression strength gradually decrease when the confining pressure increases, indicating that the anisotropy of the samples has weakened (i.e., the increase of the confining pressure decreases the anisotropy of the sandy slate strength). The failure mode of the samples with different joint angles is presented as follows: the samples with a 0° joint angle exhibit a tensile splitting damage; the samples with a 90° joint angle exhibit compression–shear damage; the samples with a 30°joint angle exhibit the combination of slide and compression–shear damage; and the samples with 45° and 60°joint angles exhibit slide damage along the joint surface.
Distributed monitoring of deformation of PCC pile under horizontal load using OFDR technology
Authors: Gao Lei , Cao Yang , Liu Han Long , Kong Gang Qiang , Cheng Xing , Zhang Xiao Lei
Published: November 2020

To study the horizontal bearing behavior of cast-in-place concrete (PCC) pipes, a horizontal static load model test is conducted based on the optical frequency domain reflectometry (OFDR) technology. The deformation distribution in the pile is studied. Results show that the pile moment increases with the horizontal load, whereas the position of the maximum point of moment is roughly unchanged. Moreover, the calculated and measured values of horizontal displacement at the pile top are compared; results show that the values are in agreement, which demonstrates that the deformation of a PCC pile can be successfully measured using the OFDR technology.
Influence of complex geological conditions on the in situ stress field of the SK Hydropower Station in Pakistan
Authors: Zhang Xinhui , Ai Kai , Yin Jianmin , Xu Chunmin
Published: November 2020

The Suki–Kinari hydropower station is situated in a landform with high mountains and deep valleys in northwest Pakistan. Affected by some geological conditions such as topography and faults, the in situ stress distribution of the project area is highly complex. To determine the in situ stress associated with this project, hydraulic fracturing in situ stress tests are conducted in four representative boreholes. Generally, the relation of the three principal stresses is σ
H
> σ
z
> σ
h
. However, the measured stress directions associated with the headrace tunnel and the powerhouse area are clearly different. The direction of the maximum horizontal principal stress of the headrace tunnel is NNE–NEE, whereas that of the underground powerhouse area is NNW–NWW. To identify the mechanism responsible for this difference, the present study simulates the stress field in the project area based on the three-dimensional finite element regression analysis method. Two theories are proposed on the basis of the numerical simulation results. On the one hand, the direction of the maximum horizontal principal stress in the rock mass above the valley elevation is controlled mainly by topography. On the other hand, the fault will disturb the stress field, causing noticeable changes in the stress direction and value of the fault-affected zone. By comparing the characteristics of the stress direction distribution at three elevations, the direction of maximum horizontal principal stress of the shallow strata is determined to be affected mainly by the topography and faults, and topography may be the most important factor. Moreover, with an increase in strata depth, the influence of the topography and faults on the stress direction decreases gradually. After reaching a particular strata depth, the direction of maximum horizontal principal stress tends to be the same as that of the regional tectonic stress, i.e., NNE.
Semi-automatic terrain slope unit division method based on human–computer interaction
Authors: Fang Hao , Tong Bin , Du Xianxiang , Li Yuan , Yang Xudong
Published: November 2020

A slope is the fundamental element of a landslide. Conducting a high-precision geohazard survey and a slope-based evaluation is important for geohazard prevention and mitigation and useful for governments in terms of improving the precision and the efficiency of geohazard management. The efficient and accurate division of slope units is the precondition of improving the accuracy and automation of a slope-based geohazard evaluation. This study introduces a semi-automatic slope unit division method that mainly includes automatic division using the geographic information system technology, followed by the revision and refinement of results by experienced professionals. Three major steps are involved in this method: 1) searching and eliminating the disturbing effect areas that could result from the disturbance of the micro-landform during the automatic division process; 2) determining the slope unit density by disclosing the relationship between the valley length and the threshold by fitting the trend with the power function; and 3) experienced professionals would perform the revision and refinement of the results generated from the previous steps to ensure that the slope unit division results meet the requirements of the slope-based evaluation. The field verification indicates that the slope units generated by the presented method are sufficient to support a slope-based evaluation on a scale of 1:10,000. The method can save considerable time and effort, which could, otherwise, be consumed during the conventional slope unit division process.
Formation setting and karst development characteristics of red beds in Wuhan, Hubei Province, China
Authors: Yin Xiansong , Luo Xiaojie , Zhang Sanding , Gao Jian
Published: November 2020

The red beds in Wuhan are mainly Cretaceous–Paleogene Donghu Group (K-Edn) strata, and the main lithologies are purplish red semi-cemented and weakly cemented mudstone, sandstone, and conglomerate. The formation setting of the red beds in Wuhan is analyzed from the regional tectonic movement and sedimentary environment. In addition, the karst development characteristics of red beds in Wuhan are studied on the basis of a large number of karst borehole data. The results show that the karst development of red beds in Wuhan is mainly controlled by the tectonic position and stratigraphic lithology. The soluble rock in the red beds of Wuhan is a calcareous cemented conglomerate, and the gravel component of conglomerate is mainly limestone. The karst phenomena in the red beds are mainly karst caves and karst fissures, while the surface karst phenomena, such as karst ditch and karst trough, are not prominent. The karstification is mainly weakly developed, and the degree of karstification positively correlates with that of the underlying karstification belt. When the lithology of the underlying formation of the red beds is carbonatite, the red bed karst is developed; by contrast, when the lithology of the underlying formation is insoluble clasolite, the red bed karst is not developed. The filling mode of the karst cave in the red beds may also be from top to bottom. The filling material mainly comes from the disintegration of the red beds themselves, and part of them comes from the overlying Quaternary strata.
Mixed Hardening Characteristics of the Anisotropic Coal under Cyclic Loading
Authors: Huang Bingxiang , Xing Yuekun , Jin Feng , Zhao Long
Published: November 2020

Pulse fracturing has been used to increase permeability and weaken the strength of the coal seam, making the coal fracture under cyclic loading. During the cyclic loading, the rock-like materials tend to present mixed hardening (mixed mode of isotropic and kinematic hardening) from initial yielding to failure (critical yielding). At present, understanding of the mixed hardening characteristics in anisotropic coal involving massive cleats remains challenging and crucial. In this paper, the cylinder specimens (diameter: 50 mm; length: 100 mm) of the coal were tested under cyclic uniaxial loading (loading rate: 900 N/s), and acoustic emission (AE) was employed to characterize the hardening process. The samples were drilled at the angle (α) of 0°, 45° and 90° with the coal surface cleat respectively. The upper-stress limit (Pmax) increases by 2 kN at each loading cycle, and the lower-stress limit (Pmin) was kept at 1 kN. Several findings were obtained based on the experimental results. (1) Uniaxial compression strength and the cyclic number increase with α, presenting isotropy. (2) The remarkable accumulation of AE energy is the feature of identifying plastic hardening. Both the isotropic and kinematic hardening processes are significant for the specimen with α dip angle (α) of 90°, validated by the dramatically increased isotropic and kinematic hardening indexes. However, the coal presents a slight isotropic and kinematic hardening, with a ranging from 0° to 45°. (3) The remarkably mixed hardening (α=90°) corresponding to a complex fragmentation of the coal, which is supposed to be caused by the continuous weakening of coal matrix (including the butt cleat). In contrast, at α of 0° and 45°, the mixed hardening characteristics are slight. Accordingly, the final fracture surfaces of coal tend to be relatively single, roughly along with the surface cleats. Thus, we can infer that the slightly mixed hardening is due to the weakening of surface cleats. Based on the mixed hardening characteristics of anisotropic coals, conducting pulse fracturing to apply cyclic loading perpendicular to the cleat surface is supposed to be beneficial for generating more complex fractures, to improve coal permeability.
Investigation of the fractal characteristics of cumulative damage to tunnel surrounding rock under blasting vibration
Authors: Xiaolong SONG , Wenxue GAO , Jinming JI , Mingban YE , Dengjie ZHANG
Published: November 2020

In this work, the cumulative damage effect of tunneling and blasting on the rock surrounding a tunnel is studied. Ground penetrating radar (GPR) is used to detect the damage of tunnel surrounding rock during blasting. and EEMD–HHT transform is used to process the obtained radar signals to obtain an intuitive representation of the damage. The relative relationship between fractal dimension and degree of damage is established to analyze the damage evolution of the tunnel surrounding rock quantitatively. The results show that the instantaneous amplitude parameter obtained by the EEMD–HHT transform could reflect the damage characteristics of the original signal and analyze the characteristics of damage evolution quantitatively. The effect of cyclic blasting causes a great direct disturbance to the area near the blast source and generates new fissures, which could aggravate the damage. The impact of blasting on areas located far from the blast source is mostly manifested as the expansion and penetration of existing cracks. The fractal dimension of the damage area is closely related to the damage evolution of the rock mass; the greater the change in fractal dimension, the more intense the damage expansion and evolution. This study quantitatively analyzes changes in the damage of tunnel surrounding rock through fractal dimensions, enriches the theoretical system of damage evolution in rock masses, and explores a new strategy to study blasting disturbances in tunnel surrounding rock.
Experimental study on seepage characteristics of coal under truly triaxial loading and unloading based on different minimum principal stress properties
Authors: Liu Zhiyuan , Wang Gang , Cheng Weimin , Qin Xiangjie , Han Dongyang
Published: November 2020

China’s coal-mining industry has developed from shallow mining to deep mining. Consequently, coal under unloading conditions is becoming increasingly complicated. In this study, seepage experiments are conducted for different minimum principal stress properties and levels of coal using a self-developed truly triaxial fluid–solid coupling seepage experimental system. In the experiment, the maximum and intermediate principal stresses correspond to the rigid stress and the minimum principal stress corresponds to the flexible stress. Experimental results show that the flexible minimum principal stress is conducive to coal deformation during axial compressive loading, whereas the rigid confining pressure inhibits coal deformation. For coal under stress unloading, the deformation and permeability of coal show a recovery change. In the initial stage of unloading, the permeability of coal shows a relatively large increase; this increase is evident in the unloading tests for rigid minimum principal stress. However, the level of the minimum principal stress is not related to the unloading effect. The findings of this study aid the prevention and control of dynamic disasters caused by coalbed gas in deep coal mining.
Quantitative study of the influence of organic-rich and natural fracture-rich regions on shale gas production
Authors: Wei S M , Jin Y , Xia Y , Zhang Y Q
Published: November 2020

Natural fractures and organic matter are randomly and unevenly distributed in shale gas reservoirs. The presence of organic-rich and natural fracture-rich regions causes the simulation results of the multi-continuum model to exhibit deviations from the real gas flow process. This paper presents a multi-continuum, discrete fracture model that captures the discontinuous nature of kerogen and natural fractures. The mathematical model describes the collision-weighted gas flow in organic matrix pores, inorganic matrix pores, and natural fractures by use of the unified flow model. The influence of organic matter and natural fractures on shale gas production is then quantitatively investigated. We find that Knudsen diffusion plays a more important role in shale gas flow than the viscous flow mechanism. Good communication between hydraulic fractures and natural fracture-rich regions can greatly improve gas production.
A new early-warning technology based on microseism and deep sliding force comprehensive monitoring for high-steep slope landslide disaster
Authors: Hui Cao , Zhigang TAO , Xiushan Qin , He Wang , Hu Ji
Published: November 2020

The accurate and efficient identification of potential slip surfaces of high-steep slopes, monitoring of deep sliding forces, and multi-source monitoring information fusion analysis and processing are the key technical problems of slope monitoring and early-warning. A new method for accurately and efficiently identifying the potential slip surfaces of high-steep slopes was proposed to solve these problems. A refined high-constant resistance energy-absorption anchor cable monitoring device was also developed, and multi-source monitoring and early-warning information fusion discrimination criteria were established. A set of new early-warning technology for open-pit slope landslide disasters based on the combination of microseism and deep sliding force monitoring was formed. This technology was used to successfully warn about landslide disasters twice or three days in advance in the demonstration mine, which effectively guided the safety management and emergency decision making. The successful development and application of this new early-warning technology provide a new idea for the safety monitoring and control technology of high-steep slopes in China.
Study on Comprehensive Treatment Technology of High-speed Railway Passing Through Giant Karst Tunnel
Authors: Wang Jun , Gu Xueqing , Liu Tongjiang , Yu Mingyang
Published: November 2020

In the mountainous areas of Southwest China, a karst landscape is well developed. There, exposed giant karst caves in the construction of high-speed railway tunnels cause great construction difficulties and safety risks for the tunnel crossing. In this paper, the study object is the project on giant karst cave of the Qianjiang–Changde railway high-mountain tunnel. After the karst cave was revealed, unmanned aerial vehicle detection, three-dimensional laser scanning, and blasting vibration monitoring were used to study the stability of the karst cave. It was found that the karst cave has a higher risk of falling rocks. On the basis of careful consideration of construction, operation safety, and economy, the “backfill cave ballast + grouting to reinforce on the upper part” scheme was determined for the treatment of the karst cave. During the process of disposal, the surface and layered settlement of backfill were monitored, in which it showed that the surface settlement control was reasonable, and the settlement mainly came from the bottom of the grouting layer, the top of non-grouting backfill, and original accumulation. To prevent the risk of falling rocks, we performed permanent safety protection of the wall and the roof for the karst cave and temporary safety protection of the mobile scaffold. Finally, the backfill treatment of the giant karst cave of high-mountain tunnel was smooth, the settlement after construction was controllable, and it met the design requirements.
Dynamics superposition mechanism analysis of the overlapped tunnel groups during the shield tunnel undercrossing
Authors: Zeng Qinghe , Ming Weihua , Luo Jin , Zhou Cuiying , Liu Zhen
Published: November 2020

Studies on superposition mechanism analysis of the old-new overlapped tunnel systems during the undercrossing process are still exploratory. Based on the viscoelastic-plastic theory of the underground structure and nonlinear evolution model of tunnel deformation and instability, the nonlinear dynamic evolution model, energy evolution model, and failure criterion of the three-dimensional (3D) tunnel system are established. The temporal and spatial superposition mechanism of the old-new overlapped tunnel system during the undercrossing process is quantitatively analyzed. The spatial expansibility and temporal continuity of the superposition mechanism are also verified. The intersecting line formula and its expansion formula of the cylinder and cone calculate the position, boundary, and volume of the superposition area. Based on the disturbed state concept theory, the disturbed function during the new shield tunnel undercrossing is theoretically derived. This study is significant for the quantitative analysis and control of the overlapped tunnel stability during the undercrossing process.
Study on the preloading effect of grouting on the tunnel lining
Authors: Xing Zhanqing , Li Jinlin , Fu Ping , Wu Xueqian , Huang Liwei
Published: November 2020

Grouting can effectively improve the stress state of the tunnel lining tensile areas under high external water pressure. To determine the relation between the permanent preloading effect and the post-grouting preloading effect on tunnel linings, several groups of grouting experiments were conducted using a grouting simulation test device developed in this research. Theoretical analysis was then performed on the basis of the experiments. Results showed that the preloading effect was severely affected by microcracks in the grouting area, although the effect gradually decreased after grouting. The ratio of the permanent effects against the post-grouting effects was shown to be a function of the drainage volume and deformation of the grouted rock mass.
Study on the Creep Characteristics of Gentle Dip Red Bed Mudstone of the Surrounding Rock Tunnel
Authors: Tang Yin , Yu Yu , Zheng Changqing , Lu Junfu
Published: November 2020

Red bed soft rock exhibits poor physical and mechanical properties and certain creep characteristics, which cause continuous deformation of tunnels and underground engineering structures during operation. The rock mass at the bottom of a railway tunnel in Sichuan Province is mudstone of the Penglaizhen Formation of the Upper Jurassic. It has a thin to medium-thick layered structure. Moreover, the rock formation is nearly horizontal. In this paper, the shear creep test and deep learning are employed to study the creep characteristics of gentle dip red bed mudstone.The results indicate that the red bed mudstone in the tunnel site exhibits medium-low creep characteristics. When the stress level is relatively low, the rate of the creep deformation gradually reduces with time, and when it reaches a certain time, the deformation no longer increases, and the final deformation tends to a stable value. Conversely, when the stress level is relatively high, although the rate of the creep deformation gradually reduces as the time increases, it remains unchanged when it reduces to a certain value. At the initial stage of creep, the deformation of each grade is evident; at the middle stage, the deformation is slow; and at the later stage, the deformation remains unchanged, that is, it enters the stable creep stage after a rapid decay in creep rate. The long-term strength of red bed mudstone in the tunnel site is low, which easily causes continuous deformation of the surrounding rock of tunnels under the action of high ground stress. According to the long-term deformation monitoring data at the bottom of the tunnel, combined with 20 groups of red bed mudstone creep parameter samples and the upper arch deformation data of the tunnel numerical model, the deep learning inverse analysis model of the creep parameter of rock mass is established based on the deep learning algorithm. Finally, we obtain the creep parameter of the red bed mudstone via inverse analysis. The research results provide a basis for engineering structure design and long-term deformation prediction of red bed mudstone strata in this area.
Comparative Analysis and Research on Electromagnetic Detection Technology of Tunnel Groundwater
Authors: Cao Guicai , Gao Guangyi , Nie Lichao
Published: November 2020

The electrical method is a sensitive technique for groundwater detection. As the tunnel develops in a deep direction, the groundwater problem becomes prominent. Thus, tunnel groundwater forecasting is particularly important. Through the advanced water exploration prediction practice in the complex geology of Gaoligongshan Tunnel, the water detection sensitivity of the complex frequency conductance (CFC) technology and the time-domain transient electromagnetic method (TEM) are compared. The advantages and disadvantages of the two methods are discussed, and the CFC technology is obtained. In accordance with the conditions of use of the time-domain transient electromagnetic method, the processing data of the CFC and the TEM method are compared with the actual excavation to reveal the groundwater development and establish a correlation.
Numerical Simulation Study of the Load Sharing of an Arched Micropile Group in the Tizicao High-Position Landslide, China
Authors: Wang Wenpei , Yin Yueping , Li Dehua , Meng Minghui , Luo Gang , Zhang Zhihua
Published: November 2020

This study presents a combined anti-sliding structural system of micropile groups, with an arched shape on the plane and cement paste between the micropiles, in the Tizicao high-position landslide study conducted in the Wenchuan seismic area, China. Improvements in the landslide’s stability as a result of the embedded micropile groups alone and in combination with long prestressed anchor cables are studied using FD-SRM and FOS contour analysis methods, respectively. The soil arching effect and the load sharing of the arched micropile group are analyzed using the numerical simulation method. Findings show that the arching effect is due to arc-shaped arrangements of the micropile groups. The design scheme of the embedded micropile groups improves the stability of this kind of thickly layered, high-position landslide. Moreover, its construction is convenient and the mechanism is clear, making it a good engineering reference for the treatment of similar landslides. The improvement in the landslide’s stability is even better than that achieved by the combination of micropile groups and long prestressed anchor cables. Furthermore, the arching effect of multiple rows of micropile groups is significant and can effectively block the movement of the sliding body. The load transfer involved in the micropile–soil interaction process is a new type of two-part load sharing pattern. The soil arching behind the micropile groups takes more than 80% of the total load. A tangential tension zone appeared along the top of the pile–group arc crown when the arch protruded upward, and a related structural performance design should be considered in the future.
Integrated Approach for the Wellbore Instability Analysis of a High-pressure, High-temperature Field in the South China Sea
Authors: Chunfang Zhang , Yu Baohua , Feng Yongcun , Yuan Juliang , Deng Jingen
Published: November 2020

Wellbore instability and lost circulation were frequently encountered while drilling the first batch of exploration wells in a low-permeability, high-pressure, high-temperature (HPHT) gas field in the South China Sea. These problems are attributed to very narrow drilling mud weight windows resulting from the HPHT reservoir conditions. This study focuses on combining and leveraging geophysical data, rock mechanics testing data, and well logging data to predict wellbore instability and lost circulation under HPHT conditions. Full-scale core samples were acquired from HPHT reservoirs of the field, and uniaxial and triaxial rock mechanics tests were performed to determine the mechanical properties of the rock. The influence of heat transfer between the wellbore and the formation, temperature field, mechanical properties, in situ stresses, collapse pressure, and fracture pressure were investigated. According to the results, changes in wellbore temperature generate thermal stress, which may aggravate wellbore instability. The wellbore temperature decreased by 50–60°C during the mud circulation process. Furthermore, the safe mud weight window, which was originally narrow because of the HPHT conditions, became narrower under the influence of temperature change. The use of multi-source data and the integrated model will significantly improve the accuracy of wellbore instability and lost circulation prediction in HPHT fields.
Application of an adaptive weighted estimation fusion algorithm in landslide deformation monitoring data processing
Authors: Yaohui Zhang , Li Wang , Bao Shu , Haibo He , Long Li
Published: November 2020

For early warning and forecast of landslide disasters, several types of sensors are used to monitor landslide deformation at different locations. In practical applications, a simple comparative analysis of the data collected at each monitoring point cannot fully use the information provided by these data. In this contribution, the use of an adaptive weighted estimation fusion algorithm is implemented to fuse the landslide deformation data collected by the Global Navigation Satellite System (GNSS) receiver and the displacement meter. The fused data are utilized for a discriminant analysis of the landslide stage. In contrast to the fusion results obtained using the original monitoring data and a back-propagation neural network, the results obtained using the adaptive weighted estimation fusion algorithm reveal that the one-sidedness of the information can be overcome using a single monitoring method and single monitoring point data. Moreover, the algorithm can provide a reliable criterion for the analysis of landslide deformation.
Climate Change under the Context of Neoliberalism: A Critical Discourse Analysis of Political Leaders’ Speeches on the Paris Agreement
Authors: Lin Yu-Chih
Published: November 2020

The aims of the Paris Agreement are against the threat of climate change. On 1st June 2017, American President Donald Trump made a speech show his stance on the Paris Agreement. On 4th November, America officially announced the process of withdrawal from the agreement had begun. It raised attentions globally. Political leaders, such as German Chancellor Angela Merkel, Former- Australian Prime Minister Malcolm Turnbull, Former- British Prime Minister Theresa May, Chinese leader Xi Jinping and French President Emmanuel Macron responded to the actions of the withdrawal action of the United States. This research examines the political leaders’ speeches to explore the embedded ideology and rationality towards the Paris Agreement under the context of neoliberalism.
Evaluating the Seismic Hazards by Chang-Hua Fault at Nantou County, Taiwan and Disaster Resistant Strategy
Authors: Liao Boi-Yee
Published: November 2020

Because of geology and complex seismic source mechanisms, Taiwan suffers attacks of earthquake calamity. In this research, we investigate the seismic hazards caused by Changhua fault and focus on the hazards at Nantou County, Taiwan. The PGA and spectral intensities, SIs, including acceleration, velocity, and displacement (SIa, SIv, and SId), are employed to estimate potential damages. The maximum seismic intensity will occur at Ming-Chien town and the buildings at Caotun Township and Nantou city will be destroyed seriously. The part of freeway 3 which connects Caotun Township and Nantou city has to be paid more attentions to prevent the destructive fractures. Based on the predicted seismic hazards, the best way to reduce the losses of lives and properties of people is preparing a well-rounded mitigation plan in advance. When an earthquake occurs abruptly, a community-based approach to establish an excellent self-aid and mutual-aid system is an efficient method for reducing the casualties. It requires a community-wide effort over a long period of time for making the community comfortable and safe. A detailed process of a community-based mitigation plan for the seismic hazards is discussed in the paper.
Education for Sustainable Development: Deficiency and Construction of Disaster Education in Universities
Authors: Xu Ping
Published: November 2020

After the outbreak of SARS, Chinese State Council published “Master State Plan for Rapid Response to Public Emergencies”. After the outbreak of Wenchuan earthquake, May 12 of each year is designated as the “National Day for Disaster Prevention and Reduction”. Modern society is transforming from industrial society to risk society. With the widespread of human-made risks, we are facing the world out of control. Emergencies may occur at any time and sometimes cause catastrophic damage to our life in a sudden. However, Chinese universities’ disaster education did not get enough attention yet. Based on the theory of risk society and discontinuous education, this research analyzed the potential deficiency in crisis education and proposed to establish a systematic crisis education curriculum as soon as possible. Also, universities should actively carry out emergency drills to simulate the real scene of disasters to the maximum extent, so university students can develop disaster instinctive response and strengthen disaster survival skills. University students should be well-prepared for the survival challenges. Disaster education plays a critical role in transforming a crisis into a real opportunity for sustainable education development.
Research on the Curriculum Development of Education for Sustainable Development(ESD) from the Perspective of VR / AR assisted instruction——Take Guangdong Business and Technology University as an Example
Authors: Du Xin Yun , Guan Yi Bo , Hsieh Tsung Shun
Published: November 2020

On September 25, 2015, the United Nations Sustainable Development Summit adopted the 2030 Agenda for sustainable development. Education, as one of these goals, is an important way to achieve sustainable development, the function and responsibility of Universities to foster sustainable development should be emphasized. About the curriculum development of Education of Sustainable Development(ESD), along with VR/AR virtual reality equipment technology getting gradually mature, it is a trend that VR/AR equipment used in the class of universities. Based on this background, we proposed two questions: how to integrate VR/AR equipment into ESD teaching and learning? Does the VR/AR device hybrid model have a significant impact on the effects of the ESD course? A total of 46 sophomore students from Guangdong Business and Technology University were selected to participate in the quasi-course experiment. We conducted a questionnaire survey of students, used statistics analysis, compared the pre-test data with the post-test ones and interviewed a teacher. We concluded that VR/AR virtual reality equipment can be integrated into the curriculum of sustainable development. This teaching and learning model has a significant impact on students’ grasp of the three dimensions: The cognitive, social emotional and the behavioral dimension of the curriculum of sustainable development. By integrating VR/AR into traditional classes, we can realize the virtualization of teaching environment and the liberalization of teaching space, further stimulate students’ learning motivation and practical interest, and realize situational and immersive teaching and learning.
Central Java smallholders: transformation and persistence through ICT development
Authors: Wijaya M I H , Wijaya H B , Priambudi B N , Ariani N M
Published: November 2020

Information communication and technology development nowadays becomes an issue in developing countries, especially Indonesia. The use of information and communication technologies (ICT) that became spearheading in the digital era is still not able to meet the needs of peoples in rural areas. This happens when there is lack of digital infrastructure between urban areas and rural areas, where ICT development is still concentrated in urban areas (city area). Agriculture has been being an important main activity in rural areas which are not yet optimized due to the digital divide. One of the drivers of the lack of digital infrastructure in rural development of the market needs to be seen from the ICT, infrastructures, and capacity of smallholders. The smallholders represent the farming activities in the current time of agriculture in Indonesia. It is essential to understand the smallholder’s phenomena and its transformation of ICT for agriculture development. The aim of the research is to identify the transformation and persistence of smallholders in Central Java Province with ICT development. This research was conducted using a qualitative approach to identify the characteristics of smallholders, the availability of ICT infrastructure, the potential for ICT development and the sustainable development of rural areas in the study area. Research using primary data was collected using interviews based on a questionnaire distributed in three regency’s in Central Java, namely: Grobogan Regency, Semarang Regency, and Demak Regency. The results of this study show that smallholders in two villages in the two study areas that have the lack of digital infrastructure challenge can persist in developing their agricultural products. The institutional transformation factor is the key to fill the needs of technological infrastructure, while smallholders in the other village are still individual and traditional.
The development of sharia capital markets and its role in financing the government projects
Authors: Naufal M D , Suharti S
Published: November 2020

The purpose of this study is to examine the possibility of sharia capital market utilization to fund government infrastructure projects and contribute knowledge and thoughts for the development of the Sharia capital market in Indonesia. The Sharia capital market expects to act as a source of funding, and it will not burden the financial condition of the government and the taxpayers. Besides that, this system will not lead a change of ownership of state assets if the government fails to pay the debt. The research methodology of this research is a literature review that sources from books, journals, and online articles. This study only examines the development of sharia capital markets and its market trading volumes contrasted to the 2015-2019 government’s infrastructure development plans. The results of this study indicate that the Sharia capital market is developing quite well in Indonesia, but it is the smallest compared to the conventional one. Therefore, the government, in this case, OJK (Financial Service Authority) needs to invite and accommodate the scholars, preachers, and imams to participate in socializing Sharia capital markets to the public.