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Landslide hazards triggered by atmospheric precipitation and periodic water level fluctuations frequently occur in reservoir areas all over the world, resulting in severe fatalities and loss of properties. For the purpose of detecting geological disasters ahead of time, a series of advance monitoring techniques have been developed and applied to engineering practices. Among them, the Distributed Fiber Optic Sensing (DFOS) technologies have shown their great potential for monitoring the tempo-spatial distribution of multi-fields (displacement, stress, temperature, seepage, etc.) of reservoir landslides. In this paper, the working principles, characteristics and applicability and these technologies are briefly introduced. In particularly, several representative DFOS-based monitoring instruments and equipment are elaborated, which have been successfully used in several landslides in Three Gorges Reservoir (TGR) area in China for long-term in situ observation and comprehensive evaluation of relevant geohazards. The monitoring results of Majiagou landslide show that the sliding surfaces, deformation pattern, and groundwater evolution can be sensitively captured based on the DFOS measurements. Seasonal rainfall and water level fluctuations are found to be the two main triggering factors of the landslide. Meanwhile, long time-series monitoring data shed a bright light on real-time deformation prediction and stability analyses of reservoir landslides. Finally, the challenges and future trends of applying the DFOS systems to landslide monitoring are summarized.
Hong-Hu Zhu; Bin Shi; Lei Zhang; Xiao Ye. Fiber Optic Monitoring and Forecasting of Reservoir Landslides. Lecture Notes in Civil Engineering 2021, 1 -13.
AMA StyleHong-Hu Zhu, Bin Shi, Lei Zhang, Xiao Ye. Fiber Optic Monitoring and Forecasting of Reservoir Landslides. Lecture Notes in Civil Engineering. 2021; ():1-13.
Chicago/Turabian StyleHong-Hu Zhu; Bin Shi; Lei Zhang; Xiao Ye. 2021. "Fiber Optic Monitoring and Forecasting of Reservoir Landslides." Lecture Notes in Civil Engineering , no. : 1-13.
Ice content is a critical parameter affecting the hydrological, thermal, and mechanical properties of frozen soil. However, it is hard to capture in-situ ice contents due to the limitations of conventional geotechnical monitoring techniques. A new method of ice content measurement for frozen soil has been recently proposed using the actively heated fiber Bragg grating (AH-FBG) sensors. This study aims to examine the feasibility of this measuring technique and investigate some critical factors related to in-situ monitoring. A series of laboratory calibration tests were performed on frozen soil specimens at the initial temperature of −17 °C. The thermal conductivities of the specimens were measured by the proposed method and compared with the results obtained using a heat transfer analyzer. To verify the effectiveness of ice content calculation and estimate the measuring accuracy while considering the presence of unfrozen water, the ice contents recorded by frequency domain reflectometry (FDR) sensors were used to provide the theoretical calculation equation of ice content reference values. Furthermore, a two-dimensional axisymmetric finite element numerical model was built to explore the influencing factors of the AH-FBG method. The experimental results indicate that this method can be used as a reliable tool for measuring ice content but have certain limitations. The series model is found to be the most suitable model for calculating thermal conductivity and ice content based on temperature changes. The numerical simulation results show that this method is applicable to ice content measurement when the initial temperature is below −6 °C and the heating duration is over 110 s. The maximum normalized radius of influence of this measuring technique is 14. To refine the proposed method for field monitoring, further studies are needed to solve these limitations and expand the scope of application.
Bing Wu; Hong-Hu Zhu; Dingfeng Cao; Liang Xu; Bin Shi. Feasibility study on ice content measurement of frozen soil using actively heated FBG sensors. Cold Regions Science and Technology 2021, 189, 103332 .
AMA StyleBing Wu, Hong-Hu Zhu, Dingfeng Cao, Liang Xu, Bin Shi. Feasibility study on ice content measurement of frozen soil using actively heated FBG sensors. Cold Regions Science and Technology. 2021; 189 ():103332.
Chicago/Turabian StyleBing Wu; Hong-Hu Zhu; Dingfeng Cao; Liang Xu; Bin Shi. 2021. "Feasibility study on ice content measurement of frozen soil using actively heated FBG sensors." Cold Regions Science and Technology 189, no. : 103332.
In this study, the actively heated fiber Bragg grating (AH-FBG) technique is developed to measure temperature and moisture profiles of partially frozen soil. The working principle of the AH-FBG sensing system is introduced, which employs an aluminum oxide tube sensor (AOTS). The unfrozen water contents and ice contents are estimated by combining AH-FBG with the frequency-domain reflection (FDR) technique. The feasibility of AH-FBG for soil moisture measurement is evaluated by laboratory and field tests under four different land covers, i.e., bare soil, concrete slab, plastic mulch (PM), and grass. It is found that AH-FBG can be used to capture unfrozen water contents and ice contents with high accuracy. The relationships between the thermal conductivity measured by AOTSs and the total water contents of frozen and unfrozen soils can be well fitted by the Côté and Konrad model. Both PM and concrete slab have a warming effect on the ground soil, which makes their depths of soil freezing shallower than that of bare soil, while the grassy land has a deeper freezing depth due to the inherent plant root-to-soil structure. The field monitoring results indicate that the PM can effectively block water migration channels at the ground surface and prevent water vapor exchange between the atmosphere and the soil, resulting in a “pot effect” that commonly exists under an impermeable layer.
Ding-Feng Cao; Hong-Hu Zhu; Bing Wu; Jia-Chen Wang; Sanjay Kumar Shukla. Investigating temperature and moisture profiles of seasonally frozen soil under different land covers using actively heated fiber Bragg grating sensors. Engineering Geology 2021, 290, 106197 .
AMA StyleDing-Feng Cao, Hong-Hu Zhu, Bing Wu, Jia-Chen Wang, Sanjay Kumar Shukla. Investigating temperature and moisture profiles of seasonally frozen soil under different land covers using actively heated fiber Bragg grating sensors. Engineering Geology. 2021; 290 ():106197.
Chicago/Turabian StyleDing-Feng Cao; Hong-Hu Zhu; Bing Wu; Jia-Chen Wang; Sanjay Kumar Shukla. 2021. "Investigating temperature and moisture profiles of seasonally frozen soil under different land covers using actively heated fiber Bragg grating sensors." Engineering Geology 290, no. : 106197.
Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties (e.g. suction and water retention) of soil. However, variations in densities alter the properties of the soil–biochar mix. Such density variations are observed in agriculture (loosely compacted) and engineering (densely compacted) applications. The influence of biochar amendment on gas permeability of soil has been barely investigated, especially for soil with different densities. The major objective of this study is to investigate the water retention capacity, and gas permeability of biochar-amended soil (BAS) with different biochar contents under varying degree of compaction (DOC) conditions. In-house produced novel biochar was mixed with the soil at different amendment rates (i.e. biochar contents of 0%, 5% and 10%). All BAS samples were compacted at three DOCs (65%, 80% and 95%) in polyvinyl chloride (PVC) tubes. Each soil column was subjected to drying–wetting cycles, during which soil suction, water content, and gas permeability were measured. A simplified theoretical framework for estimating the void ratio of BAS was proposed. The experimental results reveal that the addition of biochar significantly decreased gas permeability kg as compared with that of bare soil (BS). However, the addition of 5% biochar is found to be optimum in decreasing kg with an increase of DOC (i.e. kg,65% > kg,80% > kg,95%) at a relatively low suction range (< 200 kPa) because both biochar and compaction treatment reduce the connected pores.
Ankit Garg; He Huang; Weiling Cai; Narala Gangadhara Reddy; Peinan Chen; Yifan Han; Viroon Kamchoom; Shubham Gaurav; Hong-Hu Zhu. Influence of soil density on gas permeability and water retention in soils amended with in-house produced biochar. Journal of Rock Mechanics and Geotechnical Engineering 2021, 13, 593 -602.
AMA StyleAnkit Garg, He Huang, Weiling Cai, Narala Gangadhara Reddy, Peinan Chen, Yifan Han, Viroon Kamchoom, Shubham Gaurav, Hong-Hu Zhu. Influence of soil density on gas permeability and water retention in soils amended with in-house produced biochar. Journal of Rock Mechanics and Geotechnical Engineering. 2021; 13 (3):593-602.
Chicago/Turabian StyleAnkit Garg; He Huang; Weiling Cai; Narala Gangadhara Reddy; Peinan Chen; Yifan Han; Viroon Kamchoom; Shubham Gaurav; Hong-Hu Zhu. 2021. "Influence of soil density on gas permeability and water retention in soils amended with in-house produced biochar." Journal of Rock Mechanics and Geotechnical Engineering 13, no. 3: 593-602.
A semi-empirical Boltzmann model is proposed to describe the relationship between the rate of temperature increase and soil moisture content, which can replace the existing complicated numerical iterative algorithm. The proposed method greatly simplifies the calculation process and improves the applicability of the passive distributed temperature sensing (PDTS) technology. A field test was performed in the Loess Plateau of China to validate the capability of this method. The field site has four typical land cover conditions: bare soil (G1), plastic mulch (G2), plastic mulch cover with potatoes (G3), and plastic much cover with maize (G4). The monitoring results indicate that for G1 and G2, the relationship between soil moisture content and the rate of temperature increase can be quantitatively described by the Boltzmann model with a root-mean-square error of 0.024 m3/m3. For G3, a linear relationship is found. In contrast, the PDTS technology is not applicable for G4 because a constant ground surface heat power from solar radiation and small air temperature fluctuations are preconditions of PDTS. If the coefficient of determination (R2) for fitting rate of temperature increase is larger than 0.9, the ground surface heat power by solar radiation can be considered as a constant.
Ding-Feng Cao; Hong-Hu Zhu; Chengchao Guo; Bing Wu; Jiachen Wang. Passive distributed temperature sensing (PDTS)-based moisture content estimation in agricultural soils under different vegetative canopies. Paddy and Water Environment 2021, 1 -11.
AMA StyleDing-Feng Cao, Hong-Hu Zhu, Chengchao Guo, Bing Wu, Jiachen Wang. Passive distributed temperature sensing (PDTS)-based moisture content estimation in agricultural soils under different vegetative canopies. Paddy and Water Environment. 2021; ():1-11.
Chicago/Turabian StyleDing-Feng Cao; Hong-Hu Zhu; Chengchao Guo; Bing Wu; Jiachen Wang. 2021. "Passive distributed temperature sensing (PDTS)-based moisture content estimation in agricultural soils under different vegetative canopies." Paddy and Water Environment , no. : 1-11.
Assessment of cracks are essential for attaining better performance of landfill liner system. This study provides a new vision toward crack prevention in clayey soils. A comparative study of using various geomaterials, biomaterials, and synthetic materials to prevent the desiccation cracks formation in landfill clay liners has been performed. Small-scale materials-amended soil specimens have been subjected to extreme conditions (i.e., soil saturation to drought) for 25 days and crack-influencing parameters, such as crack intensity factor, water content, and shear strength of soil, have been obtained. The results show that addition of wood biochar (WB), pig manure biochar (PMB), and gypsum (GY) can significantly assist the soil to retain more water compared with other amendments. Furthermore, WB, PMB, and GY reduce the development of desiccation cracks in landfill liners. Altogether, this study provides useful insight toward the selection of suitable amendments for various landfill applications.
Guoxiong Mei; Himanshu Kumar; Narala Gangadhara Reddy; Shan Huang; Chandra Rahul Balaji; S. G. Sadasiv; Hong-Hu Zhu. Evaluating Suitability of Geomaterials-Amended Soil for Landfill Liner: A Comparative Study. Journal of Hazardous, Toxic, and Radioactive Waste 2020, 24, 04020052 .
AMA StyleGuoxiong Mei, Himanshu Kumar, Narala Gangadhara Reddy, Shan Huang, Chandra Rahul Balaji, S. G. Sadasiv, Hong-Hu Zhu. Evaluating Suitability of Geomaterials-Amended Soil for Landfill Liner: A Comparative Study. Journal of Hazardous, Toxic, and Radioactive Waste. 2020; 24 (4):04020052.
Chicago/Turabian StyleGuoxiong Mei; Himanshu Kumar; Narala Gangadhara Reddy; Shan Huang; Chandra Rahul Balaji; S. G. Sadasiv; Hong-Hu Zhu. 2020. "Evaluating Suitability of Geomaterials-Amended Soil for Landfill Liner: A Comparative Study." Journal of Hazardous, Toxic, and Radioactive Waste 24, no. 4: 04020052.
In order to explore the initiation of landslide-debris flow caused by concentrated runoff, a flume test has been performed on soil samples taken from a debris flow site in Wenchuan earthquake area. The fiber Bragg grating (FBG) technology was used to measure the strain distribution information in the slope mass during erosion. Several hydrological sensors for monitoring pore water pressure and soil moisture were used to investigate their correlation with internal strain field. The test results show that the fiber optic sensing technique exhibited high sensitivity and precision in monitoring the slope deformation. The development of pore water pressures and soil moistures showed reasonable consistency with the dynamics of an infiltration. According to the strain measurements, there were four evolution stages during the initiation of landslide-debris induced by runoff, i.e., the water absorption stage, the deformation stage, the shear zone formation stage, and the fluidization stage. The results provide an improved insight into the mechanism of debris flow initiation and indicate the enormous potential of the FBG sensing technology in establishing an effective early warning system for landslides and debris flows.
Hao-Jie Li; Hong-Hu Zhu; Yuan-Hai Li; Wei Hu; Bin Shi. Fiber Bragg Grating–Based Flume Test to Study the Initiation of Landslide-Debris Flows Induced by Concentrated Runoff. Geotechnical Testing Journal 2020, 44, 1 .
AMA StyleHao-Jie Li, Hong-Hu Zhu, Yuan-Hai Li, Wei Hu, Bin Shi. Fiber Bragg Grating–Based Flume Test to Study the Initiation of Landslide-Debris Flows Induced by Concentrated Runoff. Geotechnical Testing Journal. 2020; 44 (4):1.
Chicago/Turabian StyleHao-Jie Li; Hong-Hu Zhu; Yuan-Hai Li; Wei Hu; Bin Shi. 2020. "Fiber Bragg Grating–Based Flume Test to Study the Initiation of Landslide-Debris Flows Induced by Concentrated Runoff." Geotechnical Testing Journal 44, no. 4: 1.
In geo-environmental applications, the potential of biochar has been explored as a suitable cover material of landfill and vegetated slopes. The inherent nature of biochar affects the geo-environmental properties of the soil-biochar composite like water retention, compressive strength, infiltration, and soil erosion. Performance of a cover depends on biochar’s surface functional groups, which can be either hydrophobic or hydrophilic based on bio-source. The objective of this paper is to investigate the geotechnical properties of biochar-amended soil sourced from two contrasting feedstock, i.e., poultry litter (animal based) and water hyacinth (plant based). The test results show that biochar addition increased the Atterberg limits and reduced the acidity of soil. Biochar addition directly increased the optimum moisture content and decreased the maximum dry density. Both biochar addition decreased the composite compressive strength by 25–50% but increased the ductility of composite. Water hyacinth biochar (WHB) inclusion decreased the erosion rate of soil while it is not the same for poultry litter biochar (PLB). In the case of water retention, only the addition of WHB increases retention and holding capacity of soil. The obtained results have been discussed in context with the conducted microstructural, chemical, and physical tests on both biochar. Through these analyses on biochar of different origin and having contrasting functional groups and intra-pore network, the development of a complex biochar-water network was confirmed.
Sanandam Bordoloi; Himanshu Kumar; Rojimul Hussain; Ravi Karangat; Peng Lin; Sekharan Sreedeep; Hong-Hu Zhu. Assessment of hydro-mechanical properties of biochar-amended soil sourced from two contrasting feedstock. Biomass Conversion and Biorefinery 2020, 1 -16.
AMA StyleSanandam Bordoloi, Himanshu Kumar, Rojimul Hussain, Ravi Karangat, Peng Lin, Sekharan Sreedeep, Hong-Hu Zhu. Assessment of hydro-mechanical properties of biochar-amended soil sourced from two contrasting feedstock. Biomass Conversion and Biorefinery. 2020; ():1-16.
Chicago/Turabian StyleSanandam Bordoloi; Himanshu Kumar; Rojimul Hussain; Ravi Karangat; Peng Lin; Sekharan Sreedeep; Hong-Hu Zhu. 2020. "Assessment of hydro-mechanical properties of biochar-amended soil sourced from two contrasting feedstock." Biomass Conversion and Biorefinery , no. : 1-16.
The application of advanced sensing technology is of great significance for investigating the disturbance caused by tunnel excavation. In this paper, fiber Bragg grating (FBG) sensing technology is introduced into tunnel construction. To monitor the deformation in the surrounding soil, an FBG inclinometer based on the conjugate beam method is developed and then validated by laboratory calibration. Then the laboratory model test is carried out according to the actual tunnel excavation of adjacent piles. FBG-based inclinometers are used in the model test to measure the deformation of the surrounding soil, and FBG sensors are attached to the piles to monitor the pile disturbance induced by excavation. The results show that the horizontal displacement of the soil on both sides of the tunnel is distributed symmetrically up and down with the centerline of the cross-section of the tunnel. The stress redistribution of the soil above the tunnel causes a more significant surface settlement than the subsurface settlement. Moreover, the displacements of the existing piles decrease with depth and are more susceptible to the excavation sequence. Additionally, this study confirms that FBG sensing technology is suitable for monitoring tunnel excavation.
Huaibo Song; Huafu Pei; Honghu Zhu. Monitoring of tunnel excavation based on the fiber Bragg grating sensing technology. Measurement 2020, 169, 108334 .
AMA StyleHuaibo Song, Huafu Pei, Honghu Zhu. Monitoring of tunnel excavation based on the fiber Bragg grating sensing technology. Measurement. 2020; 169 ():108334.
Chicago/Turabian StyleHuaibo Song; Huafu Pei; Honghu Zhu. 2020. "Monitoring of tunnel excavation based on the fiber Bragg grating sensing technology." Measurement 169, no. : 108334.
The distributed fiber optic sensing technology has emerged as a promising tool for monitoring soil shear deformation. However, the question remains whether the strain measurements obtained by the soil-embedded optical fiber cables are reliable due to cable-soil slippage. In this paper, a direct shear model test was conducted in laboratory to characterize the cable-soil deformation compatibility considering different anchorage conditions. The optical frequency domain reflectometer was employed to measure cable strains. The measurements were compared with those from the particle image velocity technique. When the strain sensing cable couples well with soil, the cable elongation exhibits a linear relationship with the soil shear displacement. A strain integration method is then proposed to convert strain measurements into shear displacements. Furthermore, the effect of block and tube anchors on the cable-soil coupling behavior is investigated. The conclusions drawn in this study provide a reference for establishing new geotechnical deformation monitoring systems.
Han Wu; Hong-Hu Zhu; Cheng-Cheng Zhang; Gu-Yu Zhou; Bao Zhu; Wei Zhang; Mohammad Azarafza. Strain integration-based soil shear displacement measurement using high-resolution strain sensing technology. Measurement 2020, 166, 108210 .
AMA StyleHan Wu, Hong-Hu Zhu, Cheng-Cheng Zhang, Gu-Yu Zhou, Bao Zhu, Wei Zhang, Mohammad Azarafza. Strain integration-based soil shear displacement measurement using high-resolution strain sensing technology. Measurement. 2020; 166 ():108210.
Chicago/Turabian StyleHan Wu; Hong-Hu Zhu; Cheng-Cheng Zhang; Gu-Yu Zhou; Bao Zhu; Wei Zhang; Mohammad Azarafza. 2020. "Strain integration-based soil shear displacement measurement using high-resolution strain sensing technology." Measurement 166, no. : 108210.
The accuracy of landslide displacement prediction can effectively prevent casualties and economic losses. To achieve accurate prediction of the Majiagou landslide displacement in the Three Gorges Reservoir (TGR), China, a hybrid machine learning prediction model considering the deformation hysteresis effect is proposed. The real-time deep displacement measurements were captured by using in-place inclinometers with Fiber Bragg grating (FBG) sensors. The time series method was adopted to divide the total displacement into a trend term and periodic term. Trend displacement was determined by the geological condition and predicted by the fitting method. Periodic displacement was controlled by external factors such as rainfall and fluctuation of reservoir water level. Before making the prediction, the grey correlation analysis was adopted to confirm that the fluctuation of the reservoir water level was the main influence factor. In view of the deficiency that current prediction methods could not quantitatively determine the lag time of landslide deformation and thus select the influencing factors empirically, the dynamic analysis of the correlation between periodic influence factors and periodic displacement was carried out in this paper, and the deformation lag time was identified to be 18 days by using set pair analysis (SPA) method. Finally, the optimal influence factors were selected and the prediction model of Majiagou landslide based on support vector machine optimized by particle swarm optimization (SPA-PSO-SVM) was established. Results showed that the root mean square error (RMSE) and the mean absolute percentage error (MAPE) of the proposed SPA-PSO-SVM prediction model are 0.28 and 12.8, respectively. Compared with the PSO-SVM model, the prediction accuracy of the proposed model had been improved significantly. The reliability and effectiveness of the SPA-PSO-SVM prediction model is verified and it has apparent advantages while predicting landslide displacement with deformation hysteresis effect involved.
Lei Zhang; Bin Shi; Honghu Zhu; Xiong Bill Yu; Heming Han; Xudong Fan. PSO-SVM-based deep displacement prediction of Majiagou landslide considering the deformation hysteresis effect. Landslides 2020, 18, 179 -193.
AMA StyleLei Zhang, Bin Shi, Honghu Zhu, Xiong Bill Yu, Heming Han, Xudong Fan. PSO-SVM-based deep displacement prediction of Majiagou landslide considering the deformation hysteresis effect. Landslides. 2020; 18 (1):179-193.
Chicago/Turabian StyleLei Zhang; Bin Shi; Honghu Zhu; Xiong Bill Yu; Heming Han; Xudong Fan. 2020. "PSO-SVM-based deep displacement prediction of Majiagou landslide considering the deformation hysteresis effect." Landslides 18, no. 1: 179-193.
Hong-Hu Zhu; Ankit Garg; Vikas Thakur; Ningjun Jiang. Special Issue on “Materials and Processes for Ground Engineering Infrastructure”. International Journal of Geosynthetics and Ground Engineering 2020, 6, 1 .
AMA StyleHong-Hu Zhu, Ankit Garg, Vikas Thakur, Ningjun Jiang. Special Issue on “Materials and Processes for Ground Engineering Infrastructure”. International Journal of Geosynthetics and Ground Engineering. 2020; 6 (2):1.
Chicago/Turabian StyleHong-Hu Zhu; Ankit Garg; Vikas Thakur; Ningjun Jiang. 2020. "Special Issue on “Materials and Processes for Ground Engineering Infrastructure”." International Journal of Geosynthetics and Ground Engineering 6, no. 2: 1.
Distributed fiber optic sensing (DFOS) is gaining increasing interest in geotechnical monitoring. By using soil-embedded fiber optic cables, strain profiles as well as deformation patterns of geotechnical infrastructures can be captured. Probing the fiber optic cable–soil interfacial behavior is vital to the advancement of DFOS-based geotechnical monitoring and our understanding of the soil–inclusion interaction mechanism. To this aim, laboratory pullout tests were performed to investigate the progressive failure of the interface between micro-anchored cables and the surrounding sand. High-resolution strain profiles recorded using Brillouin optical time-domain analysis (BOTDA) not only elucidated the influence of anchorage on strain measurements, but also allowed the classical soil–inclusion interaction problem to be studied in detail. Interfacial shear stresses calculated from step-like strain profiles provided clear evidence of the contribution of each micro-anchor to the pullout resistance. The cable–soil contact is a combination of overall bonding and point fixation depending on the level of mobilized interfacial shear stress, and therefore the validity of measured strains is correlated to a three-stage process of interface failure. This study also shows that installing heat-shrink tubes on the fiber optic cable is a rapid, low-cost, effective approach to make an anchored DFOS system for deformation monitoring of earth structures.
Cheng-Cheng Zhang; Hong-Hu Zhu; Su-Ping Liu; Bin Shi; Gang Cheng. Quantifying progressive failure of micro-anchored fiber optic cable–sand interface via high-resolution distributed strain sensing. Canadian Geotechnical Journal 2020, 57, 871 -881.
AMA StyleCheng-Cheng Zhang, Hong-Hu Zhu, Su-Ping Liu, Bin Shi, Gang Cheng. Quantifying progressive failure of micro-anchored fiber optic cable–sand interface via high-resolution distributed strain sensing. Canadian Geotechnical Journal. 2020; 57 (6):871-881.
Chicago/Turabian StyleCheng-Cheng Zhang; Hong-Hu Zhu; Su-Ping Liu; Bin Shi; Gang Cheng. 2020. "Quantifying progressive failure of micro-anchored fiber optic cable–sand interface via high-resolution distributed strain sensing." Canadian Geotechnical Journal 57, no. 6: 871-881.
Vehicle-induced dynamic loads are far more complex than those induced by trains because of their stochastic nature. In this study, we developed the stochastic dynamic vehicle load model and addressed a series of loading scenarios for a large road shield tunnel across the Yangtze River of China. The range analysis results show that, given the three factors influencing the dynamic responses of the tunnel, the pavement roughness plays a more important role than the vehicle type and running speed. The finite element model analysis shows that stress concentration occurs around the corbels fixed to the tunnel haunches; the stress amplitude of the soil responses, ranked in the descending order, is at the tunnel sides, under the tunnel bottom and above the tunnel, respectively. Under the stochastic vehicle loads, the amplitudes of the displacement of the road shield tunnel and the maximal settlement of the surrounding soils are basically one-tenth of those of the subway tunnel; the surrounding soil stress amplitude of the road shield tunnel is about one-third of that of the subway shield tunnel; while the structural stress amplitude of the road shield tunnel, focused around the corbels, are about 4 times of that of the subway shield tunnel. Those insights can be referred by the practitioners, especially those of the cross-river combined road-and-subway shield tunnels.
Chendong Li; Wei Zhang; Xiaomin Wang; Bo Pan; Hong-Hu Zhu; Billie F. Spencer. Modeling dynamic responses of a cross-river road shield tunnel under stochastic vehicle loads. Tunnelling and Underground Space Technology 2020, 102, 103432 .
AMA StyleChendong Li, Wei Zhang, Xiaomin Wang, Bo Pan, Hong-Hu Zhu, Billie F. Spencer. Modeling dynamic responses of a cross-river road shield tunnel under stochastic vehicle loads. Tunnelling and Underground Space Technology. 2020; 102 ():103432.
Chicago/Turabian StyleChendong Li; Wei Zhang; Xiaomin Wang; Bo Pan; Hong-Hu Zhu; Billie F. Spencer. 2020. "Modeling dynamic responses of a cross-river road shield tunnel under stochastic vehicle loads." Tunnelling and Underground Space Technology 102, no. : 103432.
Growing awareness of sustainability in the landfill cover system has increased the use of biochar amendment for degraded landfill surface soils. Hydraulic and vegetative benefits of biochar on cover soil have been studied in the past, while ignoring mechanical characteristics, which is important to understand progressive failure of landfill infrastructure. In this study, the mechanical characteristics of four soil–biochar composites were investigated by conducting 81 unconfined compressive strength test. The results based on four in-house produced biochar were used to study the effect of compaction state (density, moisture content) and biochar percentage (5% and 10%) on unconfined compressive strength of soil–biochar. The ductility of soil–biochar was investigated for all the four biochars. Results from this study indicate a contrasting observation of strength gain depending on the type of biochar. The unconfined compressive strength of soil–biochar is potentially influenced by the different surface functional groups of biochar (hydrophilicity/hydrophobicity) and soil-biochar interlocking. It was noted that the peanut shell biochar gave comparable unconfined compressive strength of soil–biochar with that of bare soil for different compaction state. However, a diminution in the unconfined compressive strength was observed for all the other three soil–biochar sourced from water hyacinth, saw dust, and poultry litter. The study indicates that the use of biochar in soils does not ensure an improvement in the strength of soil–biochar. Enhancement in ductility was found for all the four soil–biochar irrespective of compaction state. Improvement in ductility was maximum when the soil–biochar is compacted at the dry state of optimum. Plant-based biochar has higher potency to increase the ductility of soil as compared to the animal-based biochar. Our study identifies peanut shell biochar ideal for landfill cover amendment material, considering its mechanical characteristics and design criterion. Soil biochar composite from water hyacinth, saw dust, and poultry litter can be used for potential application in green-infrastructure.
Manash Jyoti Bora; Sanandam Bordoloi; Himanshu Kumar; Nirmali Gogoi; Hong-Hu Zhu; Ajit K Sarmah; P Sreeja; S Sreedeep; Guoxiong Mei. Influence of biochar from animal and plant origin on the compressive strength characteristics of degraded landfill surface soils. International Journal of Damage Mechanics 2020, 30, 484 -501.
AMA StyleManash Jyoti Bora, Sanandam Bordoloi, Himanshu Kumar, Nirmali Gogoi, Hong-Hu Zhu, Ajit K Sarmah, P Sreeja, S Sreedeep, Guoxiong Mei. Influence of biochar from animal and plant origin on the compressive strength characteristics of degraded landfill surface soils. International Journal of Damage Mechanics. 2020; 30 (4):484-501.
Chicago/Turabian StyleManash Jyoti Bora; Sanandam Bordoloi; Himanshu Kumar; Nirmali Gogoi; Hong-Hu Zhu; Ajit K Sarmah; P Sreeja; S Sreedeep; Guoxiong Mei. 2020. "Influence of biochar from animal and plant origin on the compressive strength characteristics of degraded landfill surface soils." International Journal of Damage Mechanics 30, no. 4: 484-501.
Fiber‐optic sensing is emerging as a superior means for distributed strain sensing of the subsurface. The ability of an embedded fiber‐optic cable to capture accurate strain profiles depends on the degree of rigid mechanical coupling between the ground and the cable. However, a current challenge in this field is to determine the actual level of ground deformation from strain signatures sensed by the cable deployed in the subsurface; addressing this issue has been hampered by the lack of suitable theoretical methods. Here we propose a two‐step coupling evaluation procedure, whereby we develop analytical formulations to quantify the interaction and interface shear transfer of a ground–borehole–cable system. We constrain key model parameters using a dataset acquired with a fiber optics‐instrumented borehole for monitoring groundwater‐related sediment compaction. Extensive parametric analyses reveal that increasing the backfill modulus and cable gauge length or decreasing the borehole radius and cable stiffness can improve the quality of strain transferred to the cable from the ground; the effect of ground properties is comparably insignificant. Further, we develop design charts and tables at designated transfer thresholds to facilitate the development and field deployment of fiber sensing elements. Taken together, the theoretical quantification of ground–cable coupling should improve the state‐of‐the‐art performance of distributed fiber‐optic strain sensing for subsurface ground movements detection and monitoring.
Cheng‐Cheng Zhang; Bin Shi; Hong‐Hu Zhu; Bao‐Jun Wang; Guang‐Qing Wei. Toward Distributed Fiber‐Optic Sensing of Subsurface Deformation: A Theoretical Quantification of Ground‐Borehole‐Cable Interaction. Journal of Geophysical Research: Solid Earth 2020, 125, 1 .
AMA StyleCheng‐Cheng Zhang, Bin Shi, Hong‐Hu Zhu, Bao‐Jun Wang, Guang‐Qing Wei. Toward Distributed Fiber‐Optic Sensing of Subsurface Deformation: A Theoretical Quantification of Ground‐Borehole‐Cable Interaction. Journal of Geophysical Research: Solid Earth. 2020; 125 (3):1.
Chicago/Turabian StyleCheng‐Cheng Zhang; Bin Shi; Hong‐Hu Zhu; Bao‐Jun Wang; Guang‐Qing Wei. 2020. "Toward Distributed Fiber‐Optic Sensing of Subsurface Deformation: A Theoretical Quantification of Ground‐Borehole‐Cable Interaction." Journal of Geophysical Research: Solid Earth 125, no. 3: 1.
Due to its unique advantages, the distributed fiber optical sensing (DFOS) technology has been used to study the performance of inclinometer so as to monitor landslide deformation. Strain distribution of inclinometer can be obtained by distributed strain sensing (DSS) cables, and the strain-deflection relationship can be established by using the widely accepted methods (e.g., the quadratic integral method and classical conjugate beam method). However, the application of quadratic integral method and classical conjugate beam method are based on many assumptions, and there will be remarkable deviation between calculated deflection and actual displacement with the increase of integral length. Given this, a new deflection calculation method based on machine learning is proposed. Through learning on the monitoring data, an implicit function model between depth, strain, and measured displacement is established by using the BP (back propagation) neural network algorithm. The efficiency of the proposed model has been verified against measured displacement, which demonstrates the capability of this method for landslide deformation prediction. Compared with the traditional integral method, the lateral deflection curve of inclinometer calculated by the proposed method is closer to the actual measured displacement both in trend and values. The proposed model shows great potential in the application of deflection calculation in engineering.
Lei Zhang; Bin Shi; Honghu Zhu; Xiong Yu; Guangqing Wei. A machine learning method for inclinometer lateral deflection calculation based on distributed strain sensing technology. Bulletin of Engineering Geology and the Environment 2020, 79, 3383 -3401.
AMA StyleLei Zhang, Bin Shi, Honghu Zhu, Xiong Yu, Guangqing Wei. A machine learning method for inclinometer lateral deflection calculation based on distributed strain sensing technology. Bulletin of Engineering Geology and the Environment. 2020; 79 (7):3383-3401.
Chicago/Turabian StyleLei Zhang; Bin Shi; Honghu Zhu; Xiong Yu; Guangqing Wei. 2020. "A machine learning method for inclinometer lateral deflection calculation based on distributed strain sensing technology." Bulletin of Engineering Geology and the Environment 79, no. 7: 3383-3401.
As a new soil improvement method, adding nano-bentonite can enhance the engineering properties of soil. To study the stabilization effect of nano-bentonite on soil consolidation properties, a series of one-dimensional odometer tests were conducted on a clayey soil with different nano-bentonite mixing contents (i.e., 0.5%, 1%, 1.5%, and 2%). The effects of nano-bentonite on the coefficient of consolidation and permeability of the test soil were analyzed. The results show that adding a certain amount of nano-bentonite does not significantly affect the original consolidation characteristics of soil samples, but displays a notable effect on accelerating water drainage. Among all the soil samples, when the nano-bentonite mixing content is 0.5%, the final compression amount is the largest and the final void ratio is the smallest. The coefficients of consolidation and permeability increase with increasing nano-bentonite mixing content under high stress state. The test results indicate that nano-bentonite can facilitate internal cementation of soil particles, which effectively reduces the compressibility of clayey soil.
Gang Cheng; Hong-Hu Zhu; Ya-Nan Wen; Bin Shi; Lei Gao. Experimental Investigation of Consolidation Properties of Nano-Bentonite Mixed Clayey Soil. Sustainability 2020, 12, 459 .
AMA StyleGang Cheng, Hong-Hu Zhu, Ya-Nan Wen, Bin Shi, Lei Gao. Experimental Investigation of Consolidation Properties of Nano-Bentonite Mixed Clayey Soil. Sustainability. 2020; 12 (2):459.
Chicago/Turabian StyleGang Cheng; Hong-Hu Zhu; Ya-Nan Wen; Bin Shi; Lei Gao. 2020. "Experimental Investigation of Consolidation Properties of Nano-Bentonite Mixed Clayey Soil." Sustainability 12, no. 2: 459.
Soil compaction has contrasting effect on soil strength (i.e., positive) and vegetation growth (i.e., negative), respectively. Biochar has been utilized mostly in combination with soils in both agricultural fields (i.e., loose soils) and geo-structures (i.e., dense soil slopes, landfill cover) for improving water retention due to its microporous structure. Biochar is also found to be useful to reduce gas permeability in compacted soil recently. However, the efficiency of biochar in reducing gas permeability in loose and dense soils is rarely understood. The objective of this study is to analyze effects of compaction on gas permeability in soil at different degrees of compaction (i.e., 65%, 80% and 95%) and also different biochar amendment contents (0%, 5% and 10%). Another aim is to identify relative significance of parameters (soil suction, water content, biochar content and compaction) in affecting gas permeability. Experiments were conducted before applying k-nearest neighbor (KNN) modeling technique for identifying relative significance of parameters. Biochar was synthesized from a coastal invasive species (water hyacinth), which has relatively no influence on food chain (as unlike in biochar produced from biomass such as rice husk, straw, peanut shell). Based on measurements and KNN modeling, it was found that gas permeability of biochar-amended soil is relatively lower than that of soil without amendment. It was found from KNN model that for denser soils, higher amount of soil suction is mobilized for a significant increase in gas permeability as compared to loose soils. Among all parameters, soil suction is found to be most influential in affecting gas permeability followed by water content and compaction.
Ankit Garg; He Huang; Vinod Kushvaha; Priyanka Madhushri; Viroon Kamchoom; Insha Wani; Nevin Koshy; Hong-Hu Zhu. Mechanism of biochar soil pore–gas–water interaction: gas properties of biochar-amended sandy soil at different degrees of compaction using KNN modeling. Acta Geophysica 2019, 68, 207 -217.
AMA StyleAnkit Garg, He Huang, Vinod Kushvaha, Priyanka Madhushri, Viroon Kamchoom, Insha Wani, Nevin Koshy, Hong-Hu Zhu. Mechanism of biochar soil pore–gas–water interaction: gas properties of biochar-amended sandy soil at different degrees of compaction using KNN modeling. Acta Geophysica. 2019; 68 (1):207-217.
Chicago/Turabian StyleAnkit Garg; He Huang; Vinod Kushvaha; Priyanka Madhushri; Viroon Kamchoom; Insha Wani; Nevin Koshy; Hong-Hu Zhu. 2019. "Mechanism of biochar soil pore–gas–water interaction: gas properties of biochar-amended sandy soil at different degrees of compaction using KNN modeling." Acta Geophysica 68, no. 1: 207-217.
The infiltration and distribution of water through unsaturated soil determine its mechanical and hydrological properties. However, there are few methods that can accurately capture the spatial distribution of moisture inside soil. This study aims to demonstrate the use of actively heated fiber optic (AHFO) and Brillouin optical time domain analysis (BOTDA) technologies for monitoring soil moisture distribution as well as strain distribution. In addition to a laboratory model test, finite element analyses were conducted to interpret the measurements. During the experiment, the fine particle migration was also measured to understand its influence on soil hydraulic conductivity. The results of the experiment indicate that (i) for a soil that has never experienced a watering-dewatering cycle, water infiltration can be accurately calculated using the Richards’ equation; (ii) migration of fine soil particles caused by the watering-dewatering cycle significantly increases the hydraulic conductivity; and (iii) two critical zones (drainage and erosion) play significant roles in determining the overall hydraulic conductivity of the entire soil. This study provides a new method for monitoring the changes in soil moisture, soil strain, and hydraulic conductivity. The observations suggest that the effect of fine particles migration should be considered while evaluating soil moisture distribution and water movement.
Ding-Feng Cao; Bin Shi; Hong-Hu Zhu; Chao-Sheng Tang; Zhan-Pu Song; Guang-Qing Wei; Ankit Garg. Characterization of Soil Moisture Distribution and Movement Under the Influence of Watering-dewatering Using AHFO and BOTDA Technologies. Environmental and Engineering Geoscience 2019, 25, 189 -202.
AMA StyleDing-Feng Cao, Bin Shi, Hong-Hu Zhu, Chao-Sheng Tang, Zhan-Pu Song, Guang-Qing Wei, Ankit Garg. Characterization of Soil Moisture Distribution and Movement Under the Influence of Watering-dewatering Using AHFO and BOTDA Technologies. Environmental and Engineering Geoscience. 2019; 25 (3):189-202.
Chicago/Turabian StyleDing-Feng Cao; Bin Shi; Hong-Hu Zhu; Chao-Sheng Tang; Zhan-Pu Song; Guang-Qing Wei; Ankit Garg. 2019. "Characterization of Soil Moisture Distribution and Movement Under the Influence of Watering-dewatering Using AHFO and BOTDA Technologies." Environmental and Engineering Geoscience 25, no. 3: 189-202.