Search

Overburden separation grout filling (OSGF) technology compacts the fragmented rock mass in the goaf and changes the seepage characteristics and distribution of the “three zones” of spontaneous combustion in the goaf. In order to investigate the range of spontaneous combustion risks of residual coal in the goaf under the OSGF in the 22301 fully-mechanized caving face of the Tunlan Coal Mine, based on a combination of field measurement and numerical simulation, accurate demarcation of the spontaneous combustion “three zones” in the goaf was carried out. A three-dimensional mathematical model of borehole porosity was also proposed to evaluate the influence of different OSGF borehole locations on the goaf airflow field. The results show that the modified three-dimensional mathematical model of porosity can better reflect the gas flow field in the goaf after OSGF, and the residual accuracy of its simulation results is improved by 22% compared with the field measurement. Compared with the situation without OSGF, the danger of natural ignition in the goaf is effectively inhibited due to the compaction effect after OSGF. Meanwhile, the air leakage flow converges upward, resulting in an increase of oxygen concentration at higher positions in the caving zone of the goaf. The layout parameters of grouting holes will have an impact on the flow field of goaf, and the correlation degree is the spacing of holes, the number of holes and the influence radius of holes.

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the hydration process of red clay cement grout prepared by red clay in the southwest Wumeng mountain area in southwest China and the micro-morphology of the grout stone, the hydration heat characteristics of red clay cement grout were measured by direct method, and the microstructure characteristics of the hydration products of red clay cement grout were analyzed by scanning electron microscope（ＳＥＭ）, and the effects of cement and structural additives on the hydration products of red clay cement grout were studied. According to the isothermal heat release curve of red clay cement slurry, the hydration process of red clay cement slurry can be divided into acceleration period, deceleration period and stability period, and the slurry hydration kinetics equation was obtained through regression analysis. The SEM pictures of the grout stone of red clay cement grout at different ages can be clearly observed: the skeleton structure at 3 d age was relatively fluffy, forming some small pieces of C-S-H gel; at the age of 7 d, a large amount of C-S-H gel was formed, and the stone body tended to form a whole. At 28 d age, the hydration products of the stone body had basically formed and overlapped with each other to form an overall structure. The research showed that cement is the basis of the hydration reaction for the red clay cement grout. The addition of structural additives improves the hydration reaction speed of cement, thus improves the early strength of grout.

The grout vomiting value is one of the key indicators for judging the quality of Jiangxi straight rice noodles. The main factors that affect the results of the grout vomiting value are as follows: cooking time,cooking temperature, stirring, methods of pipetting et al. However, most of the above factors were not limited in DB/T222—1998 the measurement standard of grout vomiting value of Jiangxi straight rice noodles except the cooking time. It is easy to have errors in the actual measurement. Therefore, effect of four factors including cooking time, cooking temperature, stirring, and methods of pipetting on the grout vomiting were studied in this research. Result indicated that obtained data from the graphite hot plate heating method was stable and had a small error. It would be better if the grout vomiting value were expressed in the average of the three measured after every three shakes. The data will be more accurate if the pipetting area is in the middle of the volumetric flask. The stirs number during the cooking process need declare. Overcooking would increase the grout vomiting value. Partial revision of DB/T222—1998 was recommended according to this research. This study will provide a more accurate method for the detection of the grout vomiting value of Jiangxi straight rice noodles and promote the standardization of Jiangxi straight rice noodles.

The viscosity of the same natrium-based bentonite produced by different manufacturers varies greatly when the self-setting mortar is prepared with the same ratio. The essence of the viscosity is caused by the discordant microstructure of the material. Based on SEM, XRD, EDS and NMR microscopic tests, the same bentonite produced by two different manufacturers and its self-coagulated mortar were analyzed, and the viscosity microscopic mechanism was studied. The main conclusions are as follows: a) For the two bentonite grout, the viscosity is thixotropic. The establishment of "card palace" and the formation of Q4 structure will increase the viscosity, while shear will destroy the microstructure and reduce the viscosity. The content of bentonite montmorillonite from Xiangyuan is higher than that from Yulong soil, so its slurry viscosity is higher than that from Yulong soil as a whole. b) Agitation and low shear promote the dispersion of montmorillonite particles in small lamella. The more the dispersion of small lamella, the higher the viscosity of bentonite slurry after stopping shearing. c) For bentonite self-coagulant slurry, its viscosity changes mainly depend on the degree of internal charge adsorption and hydration reaction, and the C-SH gel generated by hydration reaction can promote the increase of slurry viscosity. d) The calcium carbonsulphosilicate generated in the process of condensation is not conducive to the formation of C-S-H gel. The content of calcium carbonsulphosilicate in Xiangyuan soil mortar is higher than that in Yulong soil mortar, so its overall viscosity is lower than that in Yulong soil mortar. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The stability of completely weathered granite is poor and it is easy to disintegrate when exposed to water. In engineering, the grouting effect of using conventional materials for seepage prevention and reinforcement in this rock is poor. In view of this situation, based on the grouting project of the Mangshan reservoir in Chenzhou of Hunan Province, the simulated grouting experiment is carried out by the independent design of the laboratory simulation test device. The diffusion of slurry in the whole grouting process is simulated. Uniaxial compression, shear strength and permeability tests are conducted on the samples taken at different grouting pressures and at different locations, and the whole stone body under different grouting pressures is sampled and observed to examine the anti-seepage reinforcement effect and the slurry diffusion mode of the high-solid phase segregation slurry, which is composed of fully weathered granite particles, in the fully weathered granite. The results show that the slurry has undergone three stages of permeation and diffusion, compaction and compression, and cleavage and expansion in the process of fully weathered granite formation diffusion, and the high solid phase segregation grout with fully weathered granites as the main body has a remarkable effect on the grouting of fully weathered granites. With the increasing grouting pressure, the uniaxial compressive strength is significantly increased to 3.25-13.67 times the original soil mass, and the shear strength is increased to 1.63-2.69 times the original soil mass under different normal pressures. The permeability decreases from 10−4 cm/s to 10−5 cm/s or 10−-6 cm/s. Therefore, the high solid phase segregation slurry has a significant anti-seepage effect on the fully weathered granite.

In order to study the influence of grout-filled flaws on strength and fracture modes of coal petrography, based on the test results of indoor cracked rocks, the fractured rock containing different geometric arrangements were investigated experimentally using the parallel particle flow model. The results show that the peak stress and peak strain of cracked sandstone decrease first and then increase with the increase of ligament angle. In addition, with the increase of the flaw inclination angle, the strain energy and slip friction energy of the fractured rock increase to some extent under the same ligament angle. The failure mode of the specimen mainly includes tensile failure, shear failure and tensile-shear mixture failure.

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For the purpose of researching the influence of seawater environment on the viscosity of cement sodium silicate (C-S) grout, the study tested the time-varying characteristics of grout viscosity under different water-cement (W-C) ratio, C-S volume ratio and grouting conditions (fresh water and seawater) by laboratory test method. The results showed that the viscosity of C-S grout could be divided into initial stage and rising stage under fresh water environment. In seawater environment, grout viscosity could be divided into three stages: initial stage, stable stage and rising stage. W-C ratio and C-S ratio directly affected the duration and viscosity of grout in each stage. Due to the complex ionic composition of seawater environment, the viscosity of grout rose to a certain level in a short period of time before entering a stable period of viscosity. Based on the test results, some suggestions were put forward for the construction of grouting in the unfavorable geological body of submarine tunnel, and the research conclusions had certain promoting significance for the safety construction of submarine tunnel. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lithium-based bentonite (referred to as Li-bentonite) has the advantages of strong water absorption capacity, good adsorption capacity, and high suspension performance. It is expected to make up for the defects of cement-sodium silicate (CS) slurry, which has the disadvantage of being easy to segregate and has limited accuracy in setting time adjustment. In order to find out the effects of Li-bentonite on the properties of CS slurry, the mass ratio of 0, 5%, 10%, 15%, 20%, 25% and 30% Li-bentonite was used to replace part of cement in CS slurry. The effects of Li-bentonite on the apparent viscosity, bleeding, setting time, early compressive strength and hydration products of CS grout were investigated. The mixing ratio of grouts was analyzed, and the optimal mixing ratio was obtained. The experimental results show that the Li-bentonite increases the apparent viscosity, effectively reduces the bleeding and improves the stability of slurry. The 0~10% of Li-bentonite shortens the setting time and 20% of Li-bentonite improves the early strength of the hardened slurry. In addition, it is found that the defects of CS slurry can be effectively compensated by Li-bentonite. X-Ray Diffraction test shows that no new minerals are formed in the CS grout with the addition of Li-bentonite. [ABSTRACT FROM AUTHOR]

Aiming at the problem of water loss of grout in the grouting reinforcement of fully weathered granite stratum when small pores were encountered, filtration experiments of different bentonite-superfine cement grout formulations were carried out, and the microstructure of filtration mud cakes was compared and analyzed. The results show that the content of bentonite and the morphology and morphological distribution of colloid determine the filtration property of the grouting. Appropriate addition of ultrafine cement can increase the content of fine particles and reduce filtration by making the colloid easier to fill the gap between particles. Excessive addition of ultrafine cement leads to colloid being wrapped by fine particles, which can’t prevent filtration, the filtration increased. To study the effect of colloid on the seepage, numerical simulation was studied by using finite element method. It is found that the filtration resistance of dispersed block and large and small pores is very poor, and complete membrane is the best. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northeastern University (Social Science) / Dongbei Daxue Xuebao (Shehui Kexue Ban) is the property of Dongbei Daxue and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Relying on the actual engineering case of grouting water plugging in water-rich fractured rock of Qingdao Metro, the field test of the applicability of grouting materials was carried out. The applicability of regular cement slurry, cement-sodium silicate slurry, and superfine cement slurry under the water yield standard requirements of two inspection holes, 0.2 L.min-1, m-1 and 0.01 Lmin-1 m-1, was studied. Suggestions for water plugging grouting materials in water- rich fractured rock that match the requirements of different standards were proposed. The applicability of the grouting material was verified by means of Borehole TV and actual excavation verification. Research indicated： it was difficult to meet the requirements of waterless operation by using regular cement slurry alone (the water yield from the borehole was less than 0.01 Lmin-1 m-1), but after repeated grouting, the water yield from the borehole could meet the requirement of no more than 0.2 L min-1 m-1. Cement-sodium silicate slurries had a short gel time, which could effectively limit the diffusion scope of the slurry. By coordination application of regular cement slurry and cement-sodium silicate slurry, the grouting effect was significantly better than regular cement single-liquid slurry; The superfine cement slurry had low particle size, which could effectively fill the micro-fracture space in the water-rich fractured rock and improve the water plugging efficiency of the tunnel surrounding rock. The use of regular cement slurry, cement-sodium silicate slurry and superfine cement slurry to carry out advanced curtain grouting of water-rich fractured rock could meet the requirements of tunnels waterless operation. The research results could provide a basis for the treatment design of grouting and field construction in water-rich fractured rock. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Civil Engineering & Architecture is the property of Journal of Beijing University of Civil Engineering & Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the poor geological conditions of water conveyance tunnel in Lanzhou water source construction engineering by double shield TBM excavation, the comprehensive methods and treatments were put forward by data statistics, engineering analogies, and other methods. Before TBM tunneling, F, fault zone and F, fault zone were excavated by drilling and blasting method. After initial support which guaranteed the stability of surrounding rock, TBM slided through and installed segments. Based on geological analysis along tunnel, combination the observation of tunneling face, rock muck analysis and tunneling parameter analysis, the geological conditions of surrounding rock in front of tunneling face were comprehensively predicted by using three-dimension seismic method and three-dimensional resistivity method. The principle of " drainage first, drainage and plugging combined" was adopted, the variable slope drainage system was established, the operation mode of the drainage system was determined according to the amount of water gushing. According to the characteristics of the front shield blocked, the method of releasing surrounding rock pressure by manual excavation of the heading tunnel from the telescopic shield was adopted to make the TBM out of blocked. Based on identifying geological conditions, the use of chemical grouting and cement grouting consolidation broken surrounding rock, controlling TBM tunneling parameters, slow tunneling through the fracture zone. TBM tunnneling practice shows that the adopted technology is effective and the poor geological conditions have not caused serious consequences for TBM. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the blockage mechanism of ground transport pipeline for isolated overburden grout injection, the operation condition of the slurry pipeline was monitored. Based on the measured data, the blockage of the slurry pipeline was divided into three types: adherent type, sedimentary type and comprehensive type. The formation mechanism of three types of blockage was revealed by the theoretical analysis and experimental verification of the rheological properties of pulverized coal ash and the hydration reaction of fly ash. The influence of pipeline roughness, chemical composition and flow rate on all kinds of blockage was analyzed. The results show that the adherent type was mainly influenced by the formation rate of fly ash hydration reaction gelation compound and velocity of the slurry. The sedimentary type is mainly caused by the low velocity of the slurry. In view of the above, some suggestions for preventing pipeline blockage were proposed by the authors. [ABSTRACT FROM AUTHOR]

Grouting reinforcement is an effective method for controlling the stability of engineering rock mass. The mechanism is mainly to inject or infiltrate the grout into the fracture of rock mass to form a grouting entity, and strengthen the stability of rock mass and the ability to resist failures. In order to realize the calculation of the whole process of grouting diffusion and consolidation in broken surrounding rock, a diffusion-consolidation mechanism of grouting based on discrete element method was proposed. Also, the model checking and example analysis were carried out, and the results show that: ① In the full-length grouting of single fracture scenario, the shear peak strength of the post-fractured rock mass is higher than that of the non-grouting fracture, which depends on the frictional resistance generated by the solidification and cohesion of the slurry. ② In the point grouting simulation experiment, as the grouting pressure increases, the grout continues to diffuse. Therefore, the pre-peak shear yielding and post-peak phases of the rock mass are strengthened. ③ For the engineering-scale simulation test, as the grouting pressure increases, the diffusion radius increases in two stages. When the grout expands to the high-stress area, it needs to overcome a greater compressive stress to achieve flow. After reaching a relative higher grouting pressure, the diffusion area of adjacent boreholes is superimposed to form a grouting whole body that surrounds the roadway. When the solidification bond strength of the grout is low, the failure of contact is still the main controlling factor to determine the failure and instability of the roadway.

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Advanced Engineering Science / Gongcheng Kexue Yu Jishu is the property of Advanced Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To predict the grout spread in fractured rock mass，a two-dimensional Bingham grouting model was employed based on orthogonal fracture network and a cell-centered finite volume method was used for numerical analysis. The grout spread was numerically calculated under different grouting parameters. A grouting radius formula with a grout quantity formula was put forward with the consideration of those parameters. The study results indicates that the grouting pressure，the viscosity of grout，the shear strength of grout，the aperture of fracture and the roughness of fracture dominate the grouting radius，while the grouting pressure，drilling length and the aperture of fracture dominate the grout quantity. The formulas can be used to predict the grouting radius and the grout quantity under arbitrary parameters. [ABSTRACT FROM AUTHOR]

To study the stress-strain characteristics of the slurry in the main injection horizon of overburden, the experiments on the compressive properties of fly ash slurry under different pressures were conducted by using electro-hydraulic servo universal testing machine and pressure vessel for compression test designed by the authors. The results show that under the action of overburden stress,the volume of fly ash slurry is decreased, and the decrease rate of the slurry reduces gradually；the volume of the slurry is stabilized eventually. The equivalent coefficient of compressibility of fly ash decreases with the increase of pressure, and the relationship between them is found to be logarithmic. Based on the experimental results, the relationship between the weight of fly ash and the volume of compacted fly ash slurry is established under different grouting depths, and the formula of filling ratio is improved. The formula for the limit value of fly ash used for grouting is obtained, and the engineering verification is carried out, which provides a reasonable basis for the design of weight of fly ash in grout injection engineering. [ABSTRACT FROM AUTHOR]

Copyright of Advanced Engineering Science / Gongcheng Kexue Yu Jishu is the property of Advanced Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem of insufficient bearing capacity of existing pile foundation in silty clay stratum, the effect of improving bearing capacity of existing pile foundation by side grouting was studied systematically through grouting simulation experiment. The reinforcement mechanism was mainly through the compaction effect of grouting material on the soil around the pile, increasing the friction resistance of the pile-soil interface, restricting the settlement of the pile body, and improving the bearing capacity of the pile foundation. The results showed that the grouting water cement ratio, grouting pressure, grouting hole layout position and grouting amount were the four main controlling factors for the reinforcement effect of pile foundation. The combined action of slurry water-cement ratio and grouting pressure directly affected the compaction effect of slurry on silty clay stratum by controlling the shape of slurry veins. According to the different compaction effects 5 the combination of different water cement ratio and grouting pressure was divided into three reinforcement design areas: strong5 medium and weak. Among them, the compacted soil with a slurry water-cement ratio of 0.8 and a grouting pressure of 2 MPa improved the physical and mechanical strength to the greatest extent. The increase of the bearing capacity of pile foundation was positively correlated with the amount of grouting, and inversely proportional to the distance between the formation position of grouting vein and the pile body. According to the different distance between the formation position of grouting vein and the pile body, the soil reinforced by grouting was divided into the strong action area and the weak action area. In addition, the improvement of lateral friction resistance of pile side grouting was mainly generated in the middle and lower section of pile body. In practical engineering, the reinforcement of this section reduced the consumption of manpower and material resources. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the seismic behavior of the prefabricated concrete shear wall structure with rebars splicing by grout sleeves, pseudo-dynamic substructure test on a 3-story full-scale model was performed under the excitation of earthquake record. The cracks and damage phenomena of the test model were observed. Further analysis was conducted to investigate the seismic behavior, such as the hysteretic characteristic, deformation capacity, stiffness degradation and rebar yield order. The results indicate that cracks and damage of the test model center on the coupling beams and the window belly walls in the earthquake excitation direction, characterized by bending failure in the coupling beams, shear failure in the window belly walls and slight bending failure in the wall piers. The longitudinal rebars of coupling beams, the vertical rebars of wall piers and the stirrups of coupling beams yield in turn, which indicates that the design concepts 'strong wall pier, weak coupling beam' and 'strong shear, weak bending' of coupling beam are achieved. Under frequent earthquake, design earthquake and rare earthquake of seismic fortification intensities eight, and rare earthquake of seismic fortification intensity nine, the lateral stiffness of the test model decreases about 5%, 20%, 60% and 80%, respectively, compared with the initial stiffness. The maximum inter-story drift ratios are 1/3 341, 1/899, 1/268 and 1/111 respectively under the same load conditions, which shows that the damage extent of the test model is no damage, slight damage, moderate damage and collapse, respectively. Since the concrete superposition two-way floor slabs with rebars or no rebar protruding from precast bottom slab both are of good integrity and adequate in-plane stiffness, both types of superposition floor slab can be considered as a rigid diaphragm. It is feasible by using two U-shaped rebars to form a closed stirrup instead of the ordinary stirrup in the rectangular vertical post-casting section between two precast shear walls. The connection between inner wythe and outer wythe of the precast concrete sandwich insulation wall is reliable. As the outer wythe does not participate in bearing loads, the contribution of the outer wythe can be neglected in the structural design. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to explore the diffusion law of viscosity time-denatured slurry in a dynamic water environment, taking NF cement-based slurry as the research object, the time-varying test of slurry viscosity was carried out, and the time-varying function of viscosity was determined. Based on the level set method, by customizing the viscosity time-varying function in the numerical model, the numerical simulation of dynamic water grouting considering the time-varying viscosity of the slurry is realized, and the slurry diffusion pattern and diffusion distance with and without the time-varying viscosity are obtained. The results show that the NF cement-based grouts with a water-cement ratio of 0.6 to 1.0 belong to Bingham fluid, and their viscosity increases exponentially with time. In the process of slurry diffusion, the change of slurry viscosity in the flow field shows two stages: the stable stage and the decline stage. The diffusion shape changes from circular to elliptical at the initial stage to U-shaped at the end; the slurry diffusion distance is positively correlated with time, and decreases with the decrease of water-cement ratio; the diffusion distance obtained without considering the slurry viscosity is always greater than that obtained with considering the slurry viscosity, and with the increase of grouting time, the effect of the time-varying properties of slurry viscosity on the diffusion distance is more significant.

A series of static and dynamic mechanical tests were carried out to investigate the mechanical properties of C-Type Group Material (CGM) cementitious grout and the failure law of damage under dynamic loading conditions.On the basis of the tests, the parameters of the Holmquist-Johnson-Cook (HJC) dynamic principal structure model of the material were calibrated and finite element dynamic simulations of the Split Hopkinson Pressure Bar (SHPB) test were carried out based on LS-DYNA software. The test results show that the CGM cementitious grout is mechanically stable and exhibits significant brittleness under uniaxial stress conditions, significant elastoplasticity under loading with surrounding pressure and significant rate effect under dynamic loading conditions, When the strain rate reaches 119 s-1, the dynamic peak strength can be increased by 1.62 times. The numerical simulation results show that the peak stress and peak strain of the CGM cementitious grout before damage at different strain rates can be accurately predicted using the HJC constitutive model parameters calibrated from the test data, which provides a reference for the application of this material under dynamic impact. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)