The slope stability of Ya’an expressway in Sichuan dominated by mudstone strata,is influenced greatly by both the mechanical properties and stressstrain relationship of mudstone.In this paper,the mechanical propertie...The slope stability of Ya’an expressway in Sichuan dominated by mudstone strata,is influenced greatly by both the mechanical properties and stressstrain relationship of mudstone.In this paper,the mechanical properties of the Ya’an mudstone samples under triaxial compression conditions were studied,based on an established constitutive model under the framework of breakage mechanics to simulate the mechanical properties of mudstone.Firstly,triaxial compression tests and SEM tests at the confining pressures of 0.5 MPa,1.0 MPa,and 2.0 MPa were carried out on the mudstone samples,and it was found that the mudstone sample undergoes strain softening and dilatancy followed by the volumetric compaction.Then,based on analysis on the breakage mechanism of the above test results,we idealized the mudstone sample as a binary medium material consisting of the bonded elements and frictional elements,of which the bonded elements are composed of solid matrix and pores,and the frictional elements are composed of broken aggregates.During the loading process,the cementation between clay minerals and non-clay minerals in the mudstone sample is first destroyed,leading to the formation of micro-cracks within the particle aggregate,that is,the bonded elements are gradually damaged during the loading process and gradually turned into the frictional elements,and the two jointly bear the external load.The bonded elements are composed of mudstone matrix and pores,which have the cementitious characteristics of mudstone,and the frictional elements are composed of the broken aggregate with the frictional characteristics of the broken particles.Based on the homogenization theory,the constitutive model for the mudstone is established,and the determining method for model parameters is also given.Finally,the results of the triaxial compression tests of the mudstone samples are predicted by the constitutive model proposed here,which can reflect the main mechanical properties of the mudstone samples.展开更多
During the self-weight penetration process of the suction foundation on the dense sand seabed,due to the shallow penetration depth,the excess seepage seawater from the outside to the inside of the foundation may cause...During the self-weight penetration process of the suction foundation on the dense sand seabed,due to the shallow penetration depth,the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure.Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation.The new suction anchor foundation has been proposed,and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis.For the above two foundation types,by considering five foundation diameters and two bottom shapes,20 models are tested with the same penetration energy.The effects of different foundation diameters on the penetration depth,the soil plug characteristics,and the surrounding sand layer are studied.The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation.With the same penetration energy,the penetration depth of the suction foundation becomes shallower as the diameter increases.The smaller the diameter of the suction foundation,the more likely it is to be fully plugged,and the smaller the height of the soil plug will be.In the stage of self-weight penetration,the impact cavity appears around the foundation,which may affect the stability of the suction foundation.展开更多
基金supported by Highway Planning,Survey and Design Research Institute,Sichuan Provincial Transport Department(Grant No.2020WX-15)the funding of National Natural Science Foundation of China(NSFC)(Grant No.U22A20596)。
文摘The slope stability of Ya’an expressway in Sichuan dominated by mudstone strata,is influenced greatly by both the mechanical properties and stressstrain relationship of mudstone.In this paper,the mechanical properties of the Ya’an mudstone samples under triaxial compression conditions were studied,based on an established constitutive model under the framework of breakage mechanics to simulate the mechanical properties of mudstone.Firstly,triaxial compression tests and SEM tests at the confining pressures of 0.5 MPa,1.0 MPa,and 2.0 MPa were carried out on the mudstone samples,and it was found that the mudstone sample undergoes strain softening and dilatancy followed by the volumetric compaction.Then,based on analysis on the breakage mechanism of the above test results,we idealized the mudstone sample as a binary medium material consisting of the bonded elements and frictional elements,of which the bonded elements are composed of solid matrix and pores,and the frictional elements are composed of broken aggregates.During the loading process,the cementation between clay minerals and non-clay minerals in the mudstone sample is first destroyed,leading to the formation of micro-cracks within the particle aggregate,that is,the bonded elements are gradually damaged during the loading process and gradually turned into the frictional elements,and the two jointly bear the external load.The bonded elements are composed of mudstone matrix and pores,which have the cementitious characteristics of mudstone,and the frictional elements are composed of the broken aggregate with the frictional characteristics of the broken particles.Based on the homogenization theory,the constitutive model for the mudstone is established,and the determining method for model parameters is also given.Finally,the results of the triaxial compression tests of the mudstone samples are predicted by the constitutive model proposed here,which can reflect the main mechanical properties of the mudstone samples.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52001337 and 41907244)the Guangxi Key Laboratory of Disaster Prevention and Mitigation and Engineering Safety,China(Grant No.2020ZDK002)the Key Program of Marine Economy Development(Six Marine Industries)Special Foundation of Department of Natural Resources of Guangdong Province,China(GDNRC[2020]028,GDOE[2019]A19).
文摘During the self-weight penetration process of the suction foundation on the dense sand seabed,due to the shallow penetration depth,the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure.Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation.The new suction anchor foundation has been proposed,and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis.For the above two foundation types,by considering five foundation diameters and two bottom shapes,20 models are tested with the same penetration energy.The effects of different foundation diameters on the penetration depth,the soil plug characteristics,and the surrounding sand layer are studied.The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation.With the same penetration energy,the penetration depth of the suction foundation becomes shallower as the diameter increases.The smaller the diameter of the suction foundation,the more likely it is to be fully plugged,and the smaller the height of the soil plug will be.In the stage of self-weight penetration,the impact cavity appears around the foundation,which may affect the stability of the suction foundation.
