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Numerical Simulation of Vacuum Preloading for Chemically Conditioned Municipal Sludge
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作者 Wenwei Li Xinjie Zhan +1 位作者 Baotian Wang Jinyu Zuo 《Journal of Renewable Materials》 SCIE EI 2023年第1期363-378,共16页
Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants.Among recent studies,pilot and field tests showed that chemical conditioning combined with vacuum preloading ... Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants.Among recent studies,pilot and field tests showed that chemical conditioning combined with vacuum preloading can effectively treat municipal sludge.To further understand the drainage and consolidation characteristics of the conditioning sludge during vacuum preloading,a large deformation nonlinear numerical simulation model based on the equal strain condition was developed to simulate and analyze the pilot and field tests,whereas the simulation results were not satisfactory.The results of the numerical analysis of the pilot test showed that the predicted consolidation degree was greater than that measured by the field tests,which is attributed to the relatively low permeability layer formed during the preloading process of the prefabricated vertical drain.To better reflect the consolidation process of the conditioned sludge,a simplified analysis method considering the low permeability layer around the prefabricated vertical drain was proposed.The initial permeability coefficient of the low permeability layer is determined via numerical simulations using finite difference method.The predicted settlement curve was in good agreement with the measured results,which indicated that the numerical simulation based on the equal strain condition considering the relatively low permeability layer can better analyze the consolidation process of ferric chloride-conditioning sludge with vacuum preloading. 展开更多
关键词 Sludge treatment large deformation numerical simulation chemical conditioning-combined vacuum preloading low permeability coefficient back analysis
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A New Method of Combination of Electroosmosis, Vacuum and Surcharge Preloading for Soft Ground Improvement 被引量:21
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作者 刘汉龙 崔允亮 +1 位作者 沈扬 丁选明 《China Ocean Engineering》 SCIE EI CSCD 2014年第4期511-528,共18页
As a rapid and effective ground improvement method is urgently required for the booming land reclamation in China's coastal area, this study proposes a new combined method of electroosmosis, vacuum preloading and sur... As a rapid and effective ground improvement method is urgently required for the booming land reclamation in China's coastal area, this study proposes a new combined method of electroosmosis, vacuum preloading and surcharge preloading. A new type of electrical prefabricated vertical drain (ePVD) and a new electroosmotic drainage system are suggested to allow the application of the new method. This combined method is then field-tested and compared with the conventional vacuum combined with surcharge preloading method. The monitoring and foundation test results show that the new method induces a settlement 20% larger than that of the conventional vacuum combined with surcharge preloading method in the same treatment period, and saves approximately half of the treatment time compared with the vacuum combined with surcharge preloading method according to the finite element prediction of the settlement. The proposed method also increases the vane shear strength of the soil significantly. The bearing capacity of the ground improved by use of the new proposed method raises 118%. In comparison, there is only a 75% rise when using the vacuum combined with surcharge preloading method during the same reinforcement period. All results indicate that the proposed combined method is effective and suitable for reinforcing the soft clay ground. Besides, the voltage applied between the anode and cathode increases exponentially versus treatment time when the output current of power supplies is kept constant. Most of the voltage potential in electroosmosis is lost at electrodes, leaving smaller than 50% of the voltage to be effectively transmitted into the soil. 展开更多
关键词 electroosmosis vacuum preloading surcharge preloading soft clay ground electrical resistivity
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Laboratory model study of newly deposited dredger fills using improved multiple-vacuum preloading technique 被引量:9
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作者 Jingjin Liu Huayang Lei +2 位作者 Gang Zheng Haizuo Zhou Xuelian Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2017年第5期924-935,共12页
Problems continue to be encountered concerning the traditional vacuum preloading method in field during the treatment of newly deposited dredger fills.In this paper,an improved multiple-vacuum preloading method was de... Problems continue to be encountered concerning the traditional vacuum preloading method in field during the treatment of newly deposited dredger fills.In this paper,an improved multiple-vacuum preloading method was developed to consolidate newly dredger fills that are hydraulically placed in seawater for land reclamation in Lingang Industrial Zone of Tianjin City,China.With this multiplevacuum preloading method,the newly deposited dredger fills could be treated effectively by adopting a novel moisture separator and a rapid improvement technique without sand cushion.A series of model tests was conducted in the laboratory for comparing the results from the multiple-vacuum preloading method and the traditional one.Ten piezometers and settlement plates were installed to measure the variations in excess pore water pressures and moisture content,and vane shear strength was measured at different positions.The testing results indicate that water dischargeetime curves obtained by the traditional vacuum preloading method can be divided into three phases:rapid growth phase,slow growth phase,and steady phase.According to the process of fluid flow concentrated along tiny ripples and building of larger channels inside soils during the whole vacuum loading process,the fluctuations of pore water pressure during each loading step are divided into three phases:steady phase,rapid dissipation phase,and slow dissipation phase.An optimal loading pattern which could have a best treatment effect was proposed for calculating the water discharge and pore water pressure of soil using the improved multiple-vacuum preloading method.For the newly deposited dredger fills at Lingang Industrial Zone of Tianjin City,the best loading step was 20 kPa and the loading of 40-50 k Pa produced the highest drainage consolidation.The measured moisture content and vane shear strength were discussed in terms of the effect of reinforcement,both of which indicate that the multiple-vacuum preloading method has a better treatment effect not only in decreasing the moisture content and increasing the bearing capacity,but also in increasing the process uniformity at different depths of foundation. 展开更多
关键词 Model tests Vacuum preloading Ultra-soft soil Dredger fills Cost effectiveness
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Improvement of silty clay by vacuum preloading incorporated with electroosmotic method 被引量:4
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作者 M. Q. Vu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2010年第4期365-372,共8页
A laboratory test was performed to assess the effectiveness of vacuum preloading incorporated with electroosmotic (EOM) treatment on silty clay (combined method) for reclamation projects like new disposal ponds, where... A laboratory test was performed to assess the effectiveness of vacuum preloading incorporated with electroosmotic (EOM) treatment on silty clay (combined method) for reclamation projects like new disposal ponds, where the horizontal electrode configurations beneath the soil layer were possible and the drainage pipes and the prefabricated vertical drains (PVDs) system could be easily installed in advance before the sludge dragged from sea bed or river bed was filled into the site. Three groups of tests were conducted on the silty clay from Qinhuai River in Nanjing, China. The model is able to apply vacuum pressure at the bottom of the soil layer and a direct current electric field simultaneously. It is also possible to measure the pore pressures at different depths of soil column, and the changes in settlement and volume with the elapsed time. In this study, the vacuum preloading method, vacuum preloading applied at the bottom (VAB method), was applied and the cathodes were installed beneath the soil layer. The results obtained indicate substantial reduction in water content, and increases in dry density and undrained shear strength in comparison with those obtained by the vacuum preloading only, particularly at the positions close to the anode. The combined method utilizes the vertical drainage flow created by the electroosmosis integrating the horizontal drainage flow created mostly by the vacuum pressure. The total drainage flow can be calculated as a result of the vertical drainage flow by electroosmosis only and the horizontal drainage flow by the vacuum preloading only. The way of placement of the cathode and the anode in the combined method also overcomes the disadvantage of EOM method itself, i.e. the appearance of cracks between the anode and the surrounding soil. Moreover, it is observed that the vacuum preloading plays a primary role in earlier stage in deduction of free pore water; meanwhile, the electroosmotic method is more efficient in later stage for absorbing water in the diffused double layers of soil. 展开更多
关键词 vacuum preloading VAB method soil improvement CONSOLIDATION pore pressure undrained shear strength dry density electroosmotic method
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Analysis of ground deformation development and settlement prediction by air-boosted vacuum preloading 被引量:1
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作者 Shuangxi Feng Huayang Lei Cheng Lin 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2022年第1期272-288,共17页
Vacuum preloading has been widely used to improve soft soils in coastal areas of China.An increasing amount of evidence from field operations has shown that conventional vacuum preloading is prone to clogging in prefa... Vacuum preloading has been widely used to improve soft soils in coastal areas of China.An increasing amount of evidence from field operations has shown that conventional vacuum preloading is prone to clogging in prefabricated vertical drains(PVDs)and demands a large volume of sand fills.In recent years,air-boosted vacuum preloading has been developed to overcome these limitations;however,this method still requires more data to verify its performance.In this study,a field test for air-boosted vacuum preloading was conducted,and a large-strain two-dimensional(2D)finite element(FE)model was developed and validated against the field test data.Then,a series of FE parametric analyses was performed to assess key factors,i.e.the air injection pressure,the injection spacing,and the characteristics of cyclic injection,which affect the performance of the air-boosted vacuum preloading.The results showed that the ground settlement and lateral displacement of the soils increased due to an increase in the injection pressure,a decrease in the injection spacing,or increases in the number and duration of the injection cycles.Based on the parametric analyses,an empirical formula for ground settlement prediction was proposed and compared with a case history reported in the literature,showing good agreement. 展开更多
关键词 Air-boosted vacuum preloading Field test Numerical modeling SETTLEMENT Soft soils Ground improvement
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Rigorous Axially Symmetric Consolidation Solution of Vacuum Combined Linear Loading Surcharge Preloading 被引量:1
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作者 彭劼 蒋锐 田艳梅 《Journal of Donghua University(English Edition)》 EI CAS 2018年第4期279-284,共6页
Vacuum combined surcharge preloading is an effective method which has been used in ground treatment. This study presents the analytical solution of vertical drains with vacuum combined surcharge preloading. The surcha... Vacuum combined surcharge preloading is an effective method which has been used in ground treatment. This study presents the analytical solution of vertical drains with vacuum combined surcharge preloading. The surcharge was considered to be time-dependent preloading due to its reflection of the real situation.Moreover,the free strain,instead of equal strain hypothesis of the surface,was adopted for the mathematical rigor. Both vertical and horizontal drainages,along with the well resistance were considered.Besides,the time-dependent surcharge preloading was resolved with the impulse theorem which has been presented in the study,and the solutions for pore water pressure and degree of consolidation were derived by applying the approach of separation of variables.Furthermore,the solution is compared with previous solutions and numerical solutions,and the results verify the correctness of the proposed model. 展开更多
关键词 VACUUM COMBINED SURCHARGE preloading time-dependentsurcharge CONSOLIDATION analytical SOLUTION
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Simulation Vacuum Preloading Method by Tri-Axial Apparatus 被引量:1
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作者 Ngo Trung Duong Wanchai Teparaksa Hiroyuki Tanaka 《International Journal of Geosciences》 2012年第1期211-221,共11页
It is very important to control any risk of instability of embankment during vacuum construction, the simulation vacuum preloading method using tri-axial apparatus is proposed to predict the behavior of soft soil impr... It is very important to control any risk of instability of embankment during vacuum construction, the simulation vacuum preloading method using tri-axial apparatus is proposed to predict the behavior of soft soil improvement in the laboratory, as well as to make this method become familiar and easier in the future. The tri-axial apparatus is used instead of the large-scale one, which has been performed by Bergado (1998) and Indaratna (2008). The tri-axial test on small size specimen can be carried out in one week compared to the large-scale apparatus takes one month for big specimen. In addition, the lateral deformation as well as the shear strength increase with time can determine accurately. 展开更多
关键词 Soft SOIL SOIL Improvement VACUUM preloading Degree of CONSOLIDATION
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Numerical study of rheologic and soil damage for ground improvement by vacuum preloading
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作者 吴跃东 郑世华 《Journal of Central South University》 SCIE EI CAS 2008年第S2期161-167,共7页
Based on the characteristics and reinforcement mechanism of vacuum preloading applied in high way soft foundation, the theoretical calculation method of vacuum preloading was presented. According to the equivalent met... Based on the characteristics and reinforcement mechanism of vacuum preloading applied in high way soft foundation, the theoretical calculation method of vacuum preloading was presented. According to the equivalent method derived from sand drain foundation subjected to plane and axisymmetric conditions, the three dimensional problem was transformed into plane strain problem. The modified Komala-Huang model was used to model the rheological behavior and the damage theory was also introduced to consider the effect of damage caused by construction disturbance. Numerical simulations were carried out for a high way test section. The results show that simulations of the viscoelastic-plastic-damage model are in good agreement with the field measurements. It suggests that the calculation method, simplified load and boundary condition used in this study are reasonable. 展开更多
关键词 VACUUM preloading PLANE stain FEM RHEOLOGY DAMAGE consolidate
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Characterization of Strength-Shift Behavior of Bolts Connected with and without Preloading
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作者 A.Trindade 《Journal of Mechanics Engineering and Automation》 2018年第1期9-16,共8页
Bolted joins allow for more efficient joining of parts(mechanical and structural components)when assembly and disassembly,called interchangeability,are concerned.Also and for this reason,they are the most widely used ... Bolted joins allow for more efficient joining of parts(mechanical and structural components)when assembly and disassembly,called interchangeability,are concerned.Also and for this reason,they are the most widely used in the final assembly,already in construction,in a state of final consolidation of the structure.This work began in a pedagogical action to compare the experimental results with those obtained by Eurocode 3(EN 1993-1-8)in simple joints with screws subject to cutting,the study evolved the analysis of the behavior of the screws themselves in the joint.Tests were carried out with great dimensional accuracy,for new bolted connections,with different bolt’s number,according to different arrangements and repeated in cases of simple and preloaded tightening.The experimental work,carried out on a uniaxial tensile testing machine,consisted in subjecting the connections to a growing effort so that the bolts,being subject to the cut,would break through the thread-free zone.The analysis of results and their comparison(in force—displacement diagrams)allow drawing conclusions regarding the true behavior of the bolted connections.The characterization of the thresholds of the initial zone of the force—displacement curves,in the cases of connections with preloading—was the objective of study.The transfer of forces and the influence of friction on the bonds without and with preloading were then characterized.The main objective of this project is to know the meaning of the calculated values in the preloaded and non-preloaded links by Eurocode 3. 展开更多
关键词 BOLTS connections collapsible preloading EUROCODE 3
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Consecutive Impact Loading and Preloading Effect on Stiffness of Woven Synthetic-Fiber Rope
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作者 Vannei Sry Yoshihiro Mizutani +2 位作者 Gen Endo Yoshiro Suzuki Akira Todoroki 《Journal of Textile Science and Technology》 2017年第1期1-16,共16页
We studied consecutive impact loading on woven high-modulus polyethylene rope, which is used in robotics fields. An impact tester was developed to conduct the experiments. Five consecutive impact loads (five drops) we... We studied consecutive impact loading on woven high-modulus polyethylene rope, which is used in robotics fields. An impact tester was developed to conduct the experiments. Five consecutive impact loads (five drops) were applied to the rope and the stiffness of the loading part that corresponds to each drop was evaluated. The stiffness of the woven ropes was affected strongly by consecutive impact loading. The change in stiffness is undesirable in some applications such as in robotic fields. Therefore, we have proposed a method that can optimize changes in stiffness by applying a preload before impact testing (preload treatment). The experimental results show that preload is an efficient way to reduce changing rope stiffness. We have also proposed an empirical equation that can estimate the rope stiffness after arbitrary preload treatment, and this equation is a function of the number of drops and the static preload level. The equation can be used to determine the preload treatment conditions to stabilize the stiffness of the woven ropes before they are used in engineering fields. 展开更多
关键词 Consecutive Impact Loading Woven Synthetic-Fiber ROPE STIFFNESS PRELOAD Treatment Empirical Equation Number of DROPS
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Consolidation behavior of Tianjin dredged clay using two air-booster vacuum preloading methods 被引量:4
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作者 Hua-yang LEI Yao HU +2 位作者 Jing-jin LIU Xu LIU Chen-yuan LI 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2021年第2期147-164,共18页
This paper presents model tests(macro aspect)and microstructure tests(micro aspect)for investigating the consolidation behavior of Tianjin dredged clay using the prefabricated vertical drain air-booster vacuum preload... This paper presents model tests(macro aspect)and microstructure tests(micro aspect)for investigating the consolidation behavior of Tianjin dredged clay using the prefabricated vertical drain air-booster vacuum preloading(PAVP)and tube air-booster vacuum preloading(TAVP)methods.The mechanism of air-booster vacuum preloading(AVP)using a spring-like system is explained.The main difference between these two methods is the air-boosting equipment.A new anticlogging air-booster prefabricated vertical drain(PVD)is used in the PAVP technique and a self-designed air-booster tube is used in the TAVP technique.In the model tests,a comparison of the variables that are monitored during reinforcement(vacuum pressure,surface settlement,water discharge,and pore-water pressure)and after reinforcement(water content,dry density,and vane shear strength)is conducted.The results indicate that the consolidation behavior of Tianjin dredged clay using the PAVP method is better than that using the TAVP method.PAVP more efficiently mitigates the issue of water-draining PVD clogging and significantly accelerates drainage consolidation.In addition,in the microstructure tests,a comparison of the variables that are monitored after reinforcement(via scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP))is conducted,and the results further explain the model test results. 展开更多
关键词 Tianjin dredged clay Prefabricated vertical drain air-booster vacuum preloading(PAVP) Tube air-booster vacuum preloading(TAVP) Model test Microstructure test
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基于实际预压载作业的自升式平台环境载荷图谱绘制新思路
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作者 孙承猛 林海花 +2 位作者 张志刚 孙洪源 周立师 《哈尔滨工程大学学报(英文版)》 CSCD 2024年第1期209-221,共13页
The environmental load chart is an important technical support required for the jack-up drilling platform to facilitate its adaptation to different operating waters and ensure the safety of operation.This chart is a c... The environmental load chart is an important technical support required for the jack-up drilling platform to facilitate its adaptation to different operating waters and ensure the safety of operation.This chart is a crucial part of the platform operation manual.The chart data are closely related to external factors such as water depth,wind,wave,and current conditions of the working water,as well as to the structural characteristics of the platform itself and the number of variable loads.This study examines the platform state under extreme wind,wave,and current conditions during preloading.In addition,this study focuses on the difference between the ultimate reaction force of the pile leg during preloading and the reaction force of the pile leg without considering any environmental load before preloading.Furthermore,the relationship between the difference and the new reaction force of the pile leg caused by the combination of different environmental conditions is established to facilitate the construction of a new form of environmental load chart.The newly formed chart is flexible and simple;thus,it can be used to evaluate the environmental adaptability of the platform in the target well location and provides the preloading target demand or variable load limit according to the given environmental constraints.Moreover,the platform can perform personalized preloading operations,thereby improving its capability to cope with complex geological conditions,such as reducing punch-through risks.This condition reduces the load on jacking system devices and increases its service life. 展开更多
关键词 JACK-UP Environmental load chart preloading Geometrically nonlinear effect Punch through
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Effect of preload forces on multidimensional signal dynamic behaviours for battery early safety warning
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作者 Kuijie Li Jiahua Li +10 位作者 Xinlei Gao Yao Lu Depeng Wang Weixin Zhang Weixiong Wu Xuebing Han Yuan-cheng Cao Languang Lu Jinyu Wen Shijie Cheng Minggao Ouyang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第5期484-498,共15页
Providing early safety warning for batteries in real-world applications is challenging.In this study,comprehensive thermal abuse experiments are conducted to clarify the multidimensional signal evolution of battery fa... Providing early safety warning for batteries in real-world applications is challenging.In this study,comprehensive thermal abuse experiments are conducted to clarify the multidimensional signal evolution of battery failure under various preload forces.The time-sequence relationship among expansion force,voltage,and temperature during thermal abuse under five categorised stages is revealed.Three characteristic peaks are identified for the expansion force,which correspond to venting,internal short-circuiting,and thermal runaway.In particular,an abnormal expansion force signal can be detected at temperatures as low as 42.4°C,followed by battery thermal runaway in approximately 6.5 min.Moreover,reducing the preload force can improve the effectiveness of the early-warning method via the expansion force.Specifically,reducing the preload force from 6000 to 1000 N prolongs the warning time(i.e.,227 to 398 s)before thermal runaway is triggered.Based on the results,a notable expansion force early-warning method is proposed that can successfully enable early safety warning approximately 375 s ahead of battery thermal runaway and effectively prevent failure propagation with module validation.This study provides a practical reference for the development of timely and accurate early-warning strategies as well as guidance for the design of safer battery systems. 展开更多
关键词 Lithium-ion battery Thermal runaway Preload force Expansionforce Early warning Multidimensional signal
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Research on Optimal Preload Method of Controllable Rolling Bearing Based on Multisensor Fusion
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作者 Kuosheng Jiang Chengrui Han Yasheng Chang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期3329-3352,共24页
Angular contact ball bearings have been widely used in machine tool spindles,and the bearing preload plays an important role in the performance of the spindle.In order to solve the problems of the traditional optimal ... Angular contact ball bearings have been widely used in machine tool spindles,and the bearing preload plays an important role in the performance of the spindle.In order to solve the problems of the traditional optimal preload prediction method limited by actual conditions and uncertainties,a roller bearing preload test method based on the improved D-S evidence theorymulti-sensor fusion method was proposed.First,a novel controllable preload system is proposed and evaluated.Subsequently,multiple sensors are employed to collect data on the bearing parameters during preload application.Finally,a multisensor fusion algorithm is used to make predictions,and a neural network is used to optimize the fitting of the preload data.The limitations of conventional preload testing methods are identified,and the integration of complementary information frommultiple sensors is used to achieve accurate predictions,offering valuable insights into the optimal preload force.Experimental results demonstrate that the multi-sensor fusion approach outperforms traditional methods in accurately measuring the optimal preload for rolling bearings. 展开更多
关键词 MULTI-SENSOR information fusion neural network preload force
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Near resonance vibration isolation on a levered-dual response(LEDAR)Coulomb-damped system by differential preloads/offsets in linear springs
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作者 T.I.TOLUWALOJU C.K.THEIN D.HALIM 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第6期1033-1050,共18页
The levered-dual response(LEDAR)Coulomb-damped system attains near resonant vibration isolation by differential preloads/offsets in linear springs.It takes the advantages of both the preloads/offsets in linear springs... The levered-dual response(LEDAR)Coulomb-damped system attains near resonant vibration isolation by differential preloads/offsets in linear springs.It takes the advantages of both the preloads/offsets in linear springs and the guiderail friction for realizing different levels of vibration isolation.The isolation capacities are investigated on the strategies with both the horizontal and vertical guiderails,with the horizontal rail only,and without guiderails.The compressive preloads generally result in the consumption of most of the initial excitation energy so as to overcome the potential threshold.The isolation onsets at the frequency ratio of 1∓0.095 on the left-hand side(LHS)and the right-hand side(RHS)of the lever are relative to the load plate connector.The observed near resonant isolation thus makes the LEDAR system a candidate for the isolation of the mechanical systems about resonance while opening a path for simultaneous harvesterisolation functions and passive functions at extreme frequencies. 展开更多
关键词 lever ratio Coulomb damping preload tension/compression isolation band/depth offset potential
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SEMI-ANALYTICAL METHOD FOR VACUUM PRELOADING OF A FOUNDATION WITH SAND DRAIN
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作者 赵维炳 钱家欢 《Science China Mathematics》 SCIE 1989年第3期374-384,共11页
This paper presents the consolidation analysis of a foundation (Lianyungang City)with sand drain by vacuum priloading, and the calculation of excess pore pressure with anapproximate analytic method and displacement wi... This paper presents the consolidation analysis of a foundation (Lianyungang City)with sand drain by vacuum priloading, and the calculation of excess pore pressure with anapproximate analytic method and displacement with a numerical technique. This semi-analytical method takes in account the mutual effects of 3-dimensional consolidation, soilvisco-elasticity and sand drain group. The calculation is simple. The results have been checkedfairly well with field measurements. 展开更多
关键词 FOUNDATION preloading vacuum preloading SEMI-ANALYTICAL analysis for SAND DRAIN SAND DRAIN problem VISCO-ELASTICITY of soil.
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Strength characteristics of rock anchored by NPR bolt with different preloads
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作者 SUN Xiao-ming CUI Li +2 位作者 ZHANG Yong WANG Lei JIANG Ming 《Journal of Mountain Science》 SCIE CSCD 2023年第3期834-844,共11页
This study compares the strength characteristics of rocks anchored by NPR bolts and ordinary bolts with varied preloads,based on the mechanical properties of NPR bolts(with a negative Poisson’s ratio).The results sho... This study compares the strength characteristics of rocks anchored by NPR bolts and ordinary bolts with varied preloads,based on the mechanical properties of NPR bolts(with a negative Poisson’s ratio).The results show that the uniaxial compressive stress-strain curve of ordinary anchored rocks exhibits noticeable abrupt changes.After reaching peak strength,the bolt breaks,whereas the stress-strain curve of NPR-anchored rocks is smoother.The NPR bolt enters the stage of continuous resistance after reaching maximal strength and does not break.As the preload increases,the strength of the anchored rock grows linearly.A calculation equation for the strength of the anchored rock is proposed based on the preload.The theoretical equation fits the test results well,and the fitted parameters show that NPR bolts can better increase the strength of the rock.The concept of dynamic toughness UC of anchored rock is proposed to reflect the comprehensive mechanical properties of anchored rock,including strength and plasticity.As the preload increases,the UC of ordinary anchored rock first decreases and then increases,while the UC of the NPR anchored rock does not change significantly with the preload when the strain is small,and the UC increases with the increase of the preload when the strain is large. 展开更多
关键词 NPR bolt Anchored rock Rock bolt Uniaxial compression PRELOAD Strength characteristics
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Research on Bolt Support Technology in Soft Coal Seam Roadway
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作者 Xinyuan Ma Wenzhong Zhou +2 位作者 Shuai Zhao Mingxuan Jiang Zihao Yu 《World Journal of Engineering and Technology》 2023年第2期370-380,共11页
In order to solve the problem of surrounding rock control in soft coal seam roadway, taking the centralized return airway of No. 2 coal seam in Liangdu Coal Industry as the research background, the mechanical con... In order to solve the problem of surrounding rock control in soft coal seam roadway, taking the centralized return airway of No. 2 coal seam in Liangdu Coal Industry as the research background, the mechanical conditions of roadway surrounding rock were analyzed by means of field investigation, rock mechanics experiment and numerical simulation. The design principles of roadway support in soft coal seam were put forward: high strength anchor cable support, high preload support and high stiffness support. The bearing capacity of surrounding rock was strengthened by anchor cable support, and the deformation and failure of surrounding rock were effectively controlled. Through the numerical simulation method, the deformation and plastic failure range of roadwaysunder different support schemes are compared and analyzed. The support scheme of centralized transportation roadway is studied and determined, and the field test is carried out, which effectively controls the deformation of surrounding rock of roadway in weak coal seam. 展开更多
关键词 Roadway Support High Preload High Strength Bolt Support Support Design
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Erective Sea Embankment with PCC Piles 被引量:2
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作者 刘汉龙 费康 +1 位作者 邓安 张霆 《China Ocean Engineering》 SCIE EI 2005年第2期339-348,共10页
The sea embankment is a critical civil works in marine and coastal engineering. In this study, an innovative technique is proposed for constructing erective sea embankments. In the construction of sea embankments, thi... The sea embankment is a critical civil works in marine and coastal engineering. In this study, an innovative technique is proposed for constructing erective sea embankments. In the construction of sea embankments, this technique integrates PCC pile installation, PVDs drainage systems, and geotextile reinforcements, resulting in sea embankments with PCC piles. In the application of a sea embankment with PCC piles, PCC piles are employed as the retaining structures; the soft sea ground inside PCC piles is drained and improved by PVDs and vacuum-surcharge combined preloading; geotextile-reinforced backfills lying over the improved soft ground form the embankment body. Brief descriptions of the fundamentals, design and construction of the sea embankment with PCC piles are presented. A case study on the stability of sea embankment with PCC piles is presented as well. 展开更多
关键词 sea embankment PCC piles ground treatment PVD vacuum and surcharge combined preloading reinforced backfills
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Improvements of marine clay slurries using chemicale-physical combined method(CPCM) 被引量:1
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作者 Dongqing Wu Wenyu Xu Romy Tjuar 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2015年第2期220-225,共6页
In this paper, the effectiveness, applicability and validity of chemicalephysical combined methods(CPCMs) for treatment of marine clay (MC) slurries were evaluated. The method CPCM1 combineschemical stabilization ... In this paper, the effectiveness, applicability and validity of chemicalephysical combined methods(CPCMs) for treatment of marine clay (MC) slurries were evaluated. The method CPCM1 combineschemical stabilization and vacuum preloading (VP), while CPCM2 is similar to CPCM1 but includes boththe application of surcharge and use of geo-bags to provide confinement during surcharge preloading.The key advantage of CPCM2 using geo-bags is that the surcharge can be immediately applied on thechemically stabilized slurries. Two types of geo-bags were investigated under simulated land filling anddyke conditions, respectively. The test results show that the shear strength (cu) of treated slurry byCPCM2 is generally much higher than that by CPCM1. Besides, the use of CPCM2 can significantly reducethe treatment time due to the short drainage paths created by geo-bags. Overall, CPCM2 allows fasterconsolidation and higher preloading that help to achieve higher mechanical properties of the stabilizedslurry. There are consistent relationships between cU and water content of slurries treated by CPCM2.Several important observations were also made based on comparisons of experimental data. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved. 展开更多
关键词 Chemical e physical combined method(CPCM) Soil improvement Marine clay(MC) slurry Land reclamation Chemical stabilization Vacuum preloading(VP) Geo-bags SURCHARGE
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