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| 1 | Fracture evolution analysis of soil-rock mixture in contrast with soil by CT scanning under uniaxial compressive conditions显示文摘Soil-rock mixture(SRM),as a type of extremely heterogeneous geomaterial,is very common in nature and engineering.The fracture and damage of SRM often induce severe geological disasters.Hence,it is important to analyze the fracture evolution process of this material.In the present research,real-time computed tomography(CT)scanning was conducted on SRM and pure soil samples under uniaxial compressive experiments to investigate the influence of rocks on fracture evolution in SRM.The initiation of cracks,the original values of,and variations in,average density and heterogeneity in the soil matrix,the crack width evolution during loading,and the final failure modes were all studied.Cracks with a width greater than 0.1 mm will not arise until over 90%of ultimate stress is reached.In general,in SRM,areas where the initial average density of the soil matrix is smaller and the initial heterogeneity is greater,are much easier to crack,but the results for pure soil show the opposite effect.According to fracturing conditions shown in CT slices,fracturing and non-fracturing areas in the soil matrix were investigated.The average density of the soil matrix decreases in all areas under loading,except non-fracturing areas in SRM.For the whole sample,the increase in heterogeneity in the soil matrix of SRM is greater than that of pure soil;but for the fracturing areas,this increase in pure soil is greater.Besides,the average and standard deviations of crack width both follow logarithmic distributions with high correlation coefficients. | SUN XiuKuo LI Xiao MAO TianQiao ZHENG Bo WU YanFang LI GuanFang | 2021 | Science China(Technological Sciences)2021，64，12： | 0 |
| 2 | Heterogeneity induced strain localization in block-in-matrix-soils subjected to uniaxial loading using real-time CT scanning显示文摘Block-in-matrix-soils(bimsoils)are geological mixtures that have distinct structures consisting of relatively strong rock blocks and weak matrix soils.It is still a challenge to evaluate the mechanical behaviors of bimsoils because of the heterogeneity,chaotic structure,and lithological variability.As a result,only very limited laboratory studies have been reported on the evolution of their internal deformation.In this study,the deformation evolution of bimsoils under uniaxial loading is investigated using real-time X-ray computed tomography(CT)and image correlation algorithm(with a rock block percentage(RBP)of 40%).Three parameters,i.e.heterogeneity coefficient(K),correlation coefficient(CC),and standard deviation(STD)of displacement fields,are proposed to quantify the heterogeneity of the motion of the rock blocks and the progressive deformation of the bimsoils.Experimental results show that the rock blocks in bimsoils are prone to forming clusters with increasing loading,and the sliding surface goes around only one side of a cluster.Based on the movement of the rock blocks recorded by STD and CC,the progressive deformation of the bimsoils is quantitatively divided into three stages:initialization of the rotation of rock blocks,formation of rock block clusters,and formation of a shear band by rock blocks with significant rotation.Moreover,the experimental results demonstrate that the meso-motion of rock blocks controls the macroscopic mechanical properties of the samples. | Yanfang Wu Xiao Li Luqing Zhang Shengwen Qi Jian Zhou Jianming He Zhaobin Zhang Xiukuo Sun | 2023 | Journal of Rock Mechanics and Geotechnical Engineering2023，15，8： | 0 |
| 3 | Phenomenology of plume-surface interactions and preliminary results from the Tianwen-1 landing crater on Mars显示文摘The plume-surface interaction(PSI)is a common phenomenon that describes the environment surrounding the landers resulting from the impingement of hot rocket exhaust on the regolith of planetary bodies.The PSI will cause obscuration,erosion of the planetary surface,and high-speed spreading of dust or high-energy ejecta streams,which will induce risks to a safe landing and cause damage to payloads on the landers or to nearby assets.Safe landings and the subsequent scientific goals of deep-space exploration in China call for a comprehensive understanding of the PSI process,including the plume flow mechanics,erosion mechanism,and ejecta dynamics.In addition,the landing crater caused by the plume provides a unique and insightful perspective on the understanding of PSI.In particular,the PSI can be used directly to constrain the composition,structure,and mechanical properties of the surface and subsurface soil.In this study,we conducted a systematic review of the phenomenology and terrestrial tests of PSI:we analyzed the critical factors in the PSI process and compared the differences in PSI phenomena between lunar and Martian conditions;we also reviewed the main erosion mechanisms and the evolution and development of terrestrial tests on PSI.We discuss the problems with PSI,challenges of terrestrial tests,and prospects of PSI,and we show the preliminary results obtained from the landing crater caused by the PSI of Tianwen-1.From analysis of the camera images and digital elevation model reconstructions,we concluded that the landing of Tianwen-1 caused the deepest crater(depth>40 cm)on a planetary surface reported to date and revealed stratigraphic layers in the subsurface of Martian soil.We further constrained the lower bounds of the mechanical properties of Martian soil by a slope stability analysis of the Tianwen-1 landing crater.The PSI may offer promising opportunities to obtain greater insights into planetary science,including the subsurface structure,mineral composition,and properties of soil. | Tao Xu Bo Zheng ZhaoBin Zhang Juan Li ShouDing Li XinShuo Chen XiuKuo Sun YanFang Wu YiMing Diao | 2023 | Earth and Planetary Physics2023，7，3： | 0 |
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