Stability of the Rock Mass Reserved in front of Anti-slide Piles

Dapeng Zhu,Lei He,Liangkai Qin 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

To study the stability evaluation method and failure mode of reserved rock masses, the Yueyang landslide project was taken as the research object. First, based on the limit equilibrium method and elastic mechanics, the formulas for calculating the stability of a reserved rock mass were analyzed. Second, the failure modes of the reserved rock mass were tested by the experiment model. The results show that the failure modes of the reserved rock mass can be divided into three modes: upward sliding failure, downward sliding failure and tensile crack failure, which are mainly related to the strength and width of the reserved rock mass. Therefore, it is unreasonable to regard a reserved rock mass as a unified failure form in the design of anti-slide pile reinforcement. In addition, although both moderate-strength and strong-strength reserved rock masses exhibit tensile crack failure, moderate-strength rock masses under triangular loading are prone to tension-sliding failure, while strong-strength rock masses under parabolic loading are prone to tension-overturning failure. Finally, the displacement and stress monitoring results in the experiment are basically consistent with the theoretical analysis, indicating that the theoretical analysis results have high reliability.

Radiation shielding optimization design research based on bare-bones particle swarm optimization algorithm

Jichong Lei,Chao Yang,Huajian Zhang,Chengwei Liu,Dapeng Yan,Guanfei Xiao,Zhen He,Zhenping Chen,Tao Yu Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6

In order to further meet the requirements of weight, volume, and dose minimization for new nuclear energy devices, the bare-bones multi-objective particle swarm optimization algorithm is used to automatically and iteratively optimize the design parameters of radiation shielding system material, thickness, and structure. The radiation shielding optimization program based on the bare-bones particle swarm optimization algorithm is developed and coupled into the reactor radiation shielding multi-objective intelligent optimization platform, and the code is verified by using the Savannah benchmark model. The material type and thickness of Savannah model were optimized by using the BBMOPSO algorithm to call the dose calculation code, the integrated optimized data showed that the weight decreased by 78.77%, the volume decreased by 23.10% and the dose rate decreased by 72.41% compared with the initial solution. The results show that the method can get the best radiation shielding solution that meets a lot of different goals. This shows that the method is both effective and feasible, and it makes up for the lack of manual optimization.

Mechanical performance of sand-lightweight concrete-filled steel tube stub column under axial compression

Xianggang Zhang,Dapeng Deng,Xinyan Lin,Jianhui Yang,Lei Fu 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.6

In order to study the axial compression performance of sand-lightweight concrete-filled steel tube (SLCFST) stub columns, three circular SLCFST (C-SLCFST) stub column specimens and three SLCFST square (S-SLCFST) stub column specimens were fabricated and static monotonic axial compression performance testing was carried out, using the volume ratio between river sand and ceramic sand in sand-lightweight concrete (SLC) as a varying parameter. The stress process and failure mode of the specimens were observed, stress-strain curves were obtained and analysed for the specimens, and the ultimate bearing capacity of SLCFST stub column specimens was calculated based on unified strength theory, limit equilibrium theory and superposition theory. The results show that the outer steel tubes of SLCFST stub columns buckled outward, core SLC was crushed, and the damage to the upper parts of the S-SLCFST stub columns was more serious than for C-SLCFST stub columns. Three stages can be identified in the stress-strain curves of SLCFST stub columns: an elastic stage, an elastic-plastic stage and a plastic stage. It is suggested that AIJ-1997, CECS 159:2004 or AIJ-1997, based on superposition theory, can be used to design the ultimate bearing capacity under axial compression for C-SLCFST and S-SLCFST stub columns; for varying replacement ratios of natural river sand, the calculated stress-strain curves for SLCFST stub columns under axial compression show good fitting to the test measure curves.

3-D Deformation Behavior Simulation of Cable Stitch Based on Particle System in Weft Knitted Fabrics

Sha Sha,Lei Luo,Zhongmin Deng,Dapeng Yuan,Bin Li,Xuewei Jiang,Hui Tao,Qufu Wei 한국섬유공학회 2018 Fibers and polymers Vol.19 No.9

The static simulation of weft knitting can be efficiently realized by graphics simulation techniques, but there still remains a challenge for mechanical models. The lack of practical mechanical models significantly limit the realistic deformation behaviors of complex cable stitches, which lead to a great different between the simulation effect and the actual fabric. In order to obtain the deformation behavior and volumetric performance of cable stitch, loop models were built based on an improved particle system in this work. Compared with plain weft knitted, the offset value of bonding points of cable stitches were measured. By analyzing the relationship between the deformation of loops and the displacement of the particles, the deformation behavior of cable stitch was simulated. Velocity-Verlet integration was introduced to simulate cable stitches and the stable results were obtained. The results show that these models and algorithm displayed the accurate deformation behavior of cable stitches, as demonstrated by qualitative comparisons to measure the deformations of actual samples.

Theoretical Prediction Model for Surface Settlement Caused by the Excavation of New Tunnels Undercrossing Existing Tunnels Based on Modified Stochastic Medium Theory

Qiang Xu,Shengxiang Lei,Yongquan Zhu,Wei Zhao,Cong Wang,Dapeng Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.9

The deformation pattern of the stratum caused by constructing a new metro tunnel crossing an existing tunnel is different from the deformation pattern caused by general tunnel construction. However, the prediction results by the ordinary surface settlement prediction model often bring significant errors because the complex influence of existing tunnels on the surface settlement caused by the excavation of new tunnels is always neglected. Based on the equivalent layered method and stochastic medium theory, a prediction model for the surface settlement due to excavating a new tunnel under an existing tunnel in the heterogeneous stratum was established. By equating the bending stiffness of an existing tunnel before and after applying the equivalent layered method, the layer index was determined. The critical parameters of the stochastic medium theory were derived based on the relationship between the critical parameters of both the Peck empirical formula and the stochastic medium theory. The surface settlement of some typical projects was predicted and compared by the prediction model in this paper and the ordinary prediction model. The comparison shows that the proposed prediction model and parameter determination method in this paper had high accuracy and applicability. The results of the prediction model in this paper fit the results of numerical calculation. The research of this paper can provide a new method for the theoretical prediction of surface settlement caused by the excavation of a new tunnel under an existing tunnel in the heterogeneous stratum and the determination of critical parameters of the stochastic medium theory.problem in the construction industry, and helps reducing the material waste and budget cost.

Effects of different carbon sources on the phase composition and microstructure of synthesized SiC-B4C composite powders

Yu Cao,Ruyi Deng,Jilin Hu,Jinxiu He,Dapeng Lei,Zhanjun Chen,Yangxi Peng 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2

SiC-B4C composite powders were synthesized by the carbothermal reduction method under an argon atmosphere usingdifferent kinds of carbon sources (carbon black and starch) and silica sol and boric acid as the precursor raw materials. Basedon thermodynamic analysis and calculation, the effects of different carbon sources and reaction temperatures on the mass lossrate, phase composition, and microstructure of SiC-B4C ultrafine composite powders were comparatively studied. Resultsshowed that the optimum conditions for synthesizing SiC-B4C composite powders with carbon black as the carbon source were1550 ºC for 2 h, whereas the optimum conditions for synthesizing SiC-B4C composite powders with starch as the carbon sourcewere 1450 ºC-1550 ºC for 2 h. The powder samples synthesized with carbon black as the carbon source at 1550 ºC were mainlycomposed of flaky, columnar-like, spherical, and irregular polyhedral particles (about 100-200 nm in diameter). Mutualcohesion or agglomeration between particles was minimal. In the powder samples synthesized at 1550 ºC with an excess of 10wt% starch, in addition to a certain amount of flaky, spherical, and other irregular structure particles, a certain amount ofuniform, slender whiskers (about 50-100 nm in diameter) and a certain phenomenon of lap and winding between the whiskerswere noted. The powder samples synthesized at 1550 ºC with an excess of 20 wt% starch had no whisker-like substance.