Civil construction has high demand for new procedures and technologies capable of generating better results in numerous situations throughout the process.Nowadays,cavities in urban areas are commonly used due to the i...Civil construction has high demand for new procedures and technologies capable of generating better results in numerous situations throughout the process.Nowadays,cavities in urban areas are commonly used due to the implantation of commercial and residential developments with more than two floors,seeking a better use of the nobler areas of the big cities.In geotechnical terms,the filling of these cavities,with the local soil,especially in the Federal District,lateritic soils,can represent additional efforts for the structures and foundations and lead to a compromise of the technical and functional performance of the same,compromising the efficiency and the economy of the enterprise.In this sense,this research evaluates the mechanical behavior of the mixtures,using GEO5 Software,Containment Design and Verification Modules,presenting an alternative to fill cavities in urban regions,with a mixture of material with lower specific density in relation to the soil Natural.Proctor Normal compression tests,simple direct shear saturation and sample expansibility were performed.The results showed a reduction of 38%in the strength of the reinforced concrete curtain,as well as a 25%reduction in maximum bending moments and 31%in maximum shear forces,and a reduction of about 32%in the displacements of the structure to the soil with addition of expanded vermiculite for tests obtained in the saturated condition.For the compositions of cement soil,expanded vermiculite soil and soil cement and expanded vermiculite,the deformations were of the order of 0.3%,0.4%and 0.2%,respectively.展开更多
Based on five basic assumptions, of the ground subsidence and collapse was using theoretical analysis method, the nature revealed from the mechanics point. Divided into four phases as groundwater level descent, soil c...Based on five basic assumptions, of the ground subsidence and collapse was using theoretical analysis method, the nature revealed from the mechanics point. Divided into four phases as groundwater level descent, soil cavity formation, soil cavity expansion, and ground collapse emersion, the whole process of ground subsidence and collapse was analyzed in detail. The study shows that ground subsidence and collapse is the macro- scopic performance and inevitable result of the soil cavity expansion and development, and the dynamic mechanics is the spalling force induced by the groundwater falling. The activities of underground water play a very important role in the process from the formation of soil cavity to the production of ground subsidence.展开更多
Rapid advances in deep-sea mining engineering have created an urgent need for the accurate evaluation of the undrained strength of marine soils,especially surface soils.Significant achievements have been made using fu...Rapid advances in deep-sea mining engineering have created an urgent need for the accurate evaluation of the undrained strength of marine soils,especially surface soils.Significant achievements have been made using full-flow penetration penetrometers to evaluate marine soil strength in the deep penetration;however,a method considering the effect of ambient water on the surface penetration needs to be established urgently.In this study,penetrometers with multiple probes were developed and used to conduct centrifuge experiments on South China Sea soil and kaolin clay.First,the forces on the probes throughout the penetration process were systematically analyzed and quantified.Second,the spatial influence zone was determined by capturing the resistance changes and sample crack development,and the penetration depth for a sample to reach a stable failure mode was given.Third,the vane shear strength was used to invert the penetration resistance factor of the ball and determine the range of the penetration resistance factor values.Furthermore,a methodology to determine the penetration resistance factors for surface marine soils was established.Finally,the effect of the water cavity above various probes in the surface penetration was used to formulate an internal mechanism for variations in the penetration resistance factor.展开更多
A high-sensitivity low-temperature sensor based on Fabry-Pérot interferometer(FPI)is fabricated and experimentally demonstrated in this letter.The FPI air cavity is fabricated by splicing a single-mode optical fi...A high-sensitivity low-temperature sensor based on Fabry-Pérot interferometer(FPI)is fabricated and experimentally demonstrated in this letter.The FPI air cavity is fabricated by splicing a single-mode optical fiber(SMF)with a glass capillary tube partially filled with ultraviolet(UV)glue.Due to the high coefficient of thermal expansion of UV-glue,the sensor can obtain high sensitivity.Experimental results show that the sensor has a temperature sensitivity of-3.7534 nm/℃in the temperature range of-4—4℃,and the linearity is 0.999.The engineering performance of the sensor is tested by simulating the frozen soil environment.The proposed sensor has high sensitivity and good temperature response.The sensor structure is compact and simple,low cost and has potential application in the cryogenic detection environment.展开更多
In this paper,an anisotropic critical state model for saturated soils was extended to unsaturated conditions by introducing suction into its yield function.Combining this model with soil-water characteristic curves re...In this paper,an anisotropic critical state model for saturated soils was extended to unsaturated conditions by introducing suction into its yield function.Combining this model with soil-water characteristic curves related to porosity ratio was employed to characterize the coupled hydromechanical behavior of unsaturated anisotropic soil.Based on the plane stress condition,the problem of the cylindrical cavity expansion in unsaturated anisotropic soils was transformed into first-order differential equations using the Lagrangian description.The equations were solved as an initial value problem using the Runge-Kutta algorithm,which can reflect the soil-water retention behavior during cavity expansion.Parametric analyses were conducted to investigate the influences of overconsolidation ratio(OCR),suction,and degree of saturation on the expansion responses of a cylindrical cavity in unsaturated anisotropic soil under plane stress condition.The results show that the above factors have obvious influences on the cavity responses,and the plane strain solution tends to overestimate expansion pressure and degree of saturation but underestimates suction around the cavity compared to the proposed plane stress solution.The theoretical model proposed in this paper provides a reasonable and effective method for simulating pile installation and soil pressure gauge tests near the ground surface of the unsaturated soils.展开更多
The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by ...The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.展开更多
Based on the generally adopted soil model for engineering, an analytic solution of spherical wave propagation problem in a special case for an equally pressurized spherical cavity in saturated space by Laplace transfo...Based on the generally adopted soil model for engineering, an analytic solution of spherical wave propagation problem in a special case for an equally pressurized spherical cavity in saturated space by Laplace transformation which is compared with that of the same problem in a one-phase elastic space. The influence of fluid on dynamic response of saturated soil is examined. The authors propose an effective way for dynamic analysis of underground structure.展开更多
Jets caused by burst tubes erode the surrounding soil, eventually leading to issues such as ground collapse. It is therefore highly important to study the mechanisms of soil erosion caused by jets after pipeline leaka...Jets caused by burst tubes erode the surrounding soil, eventually leading to issues such as ground collapse. It is therefore highly important to study the mechanisms of soil erosion caused by jets after pipeline leakage. To investigate the water-soil interaction mechanisms of pipe leakage, this study used transparent soil and developed a three-dimensional experimental device to observe the fluidization process. Changes in the boundary of the fluidization transition area were investigated, and a formula for calculating the soil damage area was derived. The results showed three different shapes of the fluidized cavity appearing in the fluidization process. The particles initially moved upward and then gradually transitioned into a state of backflow. The effects of particle size, upper load, and porosity on fluidization were also analyzed. It was found that soil with a large particle size and a lower porosity under a heavy upper load can effectively restrain fluidization. Therefore, large-diameter and dense soil can be used as pipe-covering material.展开更多
This paper presents an undrained semi-analytical elastoplastic solution for cylindrical cavity expansion in anisotropic soil under the biaxial stress conditions.The advanced simplified SANICLAY model is used to simula...This paper presents an undrained semi-analytical elastoplastic solution for cylindrical cavity expansion in anisotropic soil under the biaxial stress conditions.The advanced simplified SANICLAY model is used to simulate the elastoplastic behavior of soil.The cavity expansion is treated as an initial value problem and solved as a system of eight first-order ordinary differential equations including four stress components and four anisotropic parameters.The results are validated by comparing the new solutions with existing ones.The distributions of stress components and anisotropic parameters around the cavity wall,the expansion process,the stress yield trajectory of a soil element and the shape and size of elastoplastic boundary are further investigated to explore the cavity expansion response of soils under biaxial in situ stresses.The results of extensive parameters analysis demonstrate that the circumferential position of the soil element and the anisotropy of the soils have noticeable impacts on the expansion response under biaxial in situ stresses.Since the present solution not only considers the anisotropy and anisotropy evolution of natural soil,but also eliminates the conventional assumption of uniform radial pressure,the solution is better than other theoretical solutions to explain the pressure test and pile installation effect of shallow saturated soil.展开更多
文摘Civil construction has high demand for new procedures and technologies capable of generating better results in numerous situations throughout the process.Nowadays,cavities in urban areas are commonly used due to the implantation of commercial and residential developments with more than two floors,seeking a better use of the nobler areas of the big cities.In geotechnical terms,the filling of these cavities,with the local soil,especially in the Federal District,lateritic soils,can represent additional efforts for the structures and foundations and lead to a compromise of the technical and functional performance of the same,compromising the efficiency and the economy of the enterprise.In this sense,this research evaluates the mechanical behavior of the mixtures,using GEO5 Software,Containment Design and Verification Modules,presenting an alternative to fill cavities in urban regions,with a mixture of material with lower specific density in relation to the soil Natural.Proctor Normal compression tests,simple direct shear saturation and sample expansibility were performed.The results showed a reduction of 38%in the strength of the reinforced concrete curtain,as well as a 25%reduction in maximum bending moments and 31%in maximum shear forces,and a reduction of about 32%in the displacements of the structure to the soil with addition of expanded vermiculite for tests obtained in the saturated condition.For the compositions of cement soil,expanded vermiculite soil and soil cement and expanded vermiculite,the deformations were of the order of 0.3%,0.4%and 0.2%,respectively.
基金Supported by the National Natural Science Foundation of China(10702072)the Technology Innovation Fundation of China Coal Research Institute(2009CX01)
文摘Based on five basic assumptions, of the ground subsidence and collapse was using theoretical analysis method, the nature revealed from the mechanics point. Divided into four phases as groundwater level descent, soil cavity formation, soil cavity expansion, and ground collapse emersion, the whole process of ground subsidence and collapse was analyzed in detail. The study shows that ground subsidence and collapse is the macro- scopic performance and inevitable result of the soil cavity expansion and development, and the dynamic mechanics is the spalling force induced by the groundwater falling. The activities of underground water play a very important role in the process from the formation of soil cavity to the production of ground subsidence.
基金partially supported by the National Key Research and Development Program of China(No.2018YFC0309200)the National Natural Science Foundation of China(No.51879036)+1 种基金the LiaoNing Revitalization Talents Program(No.XLYC2002036)the Fundamental Research Funds for the Central Universities of Dalian University of Technology。
文摘Rapid advances in deep-sea mining engineering have created an urgent need for the accurate evaluation of the undrained strength of marine soils,especially surface soils.Significant achievements have been made using full-flow penetration penetrometers to evaluate marine soil strength in the deep penetration;however,a method considering the effect of ambient water on the surface penetration needs to be established urgently.In this study,penetrometers with multiple probes were developed and used to conduct centrifuge experiments on South China Sea soil and kaolin clay.First,the forces on the probes throughout the penetration process were systematically analyzed and quantified.Second,the spatial influence zone was determined by capturing the resistance changes and sample crack development,and the penetration depth for a sample to reach a stable failure mode was given.Third,the vane shear strength was used to invert the penetration resistance factor of the ball and determine the range of the penetration resistance factor values.Furthermore,a methodology to determine the penetration resistance factors for surface marine soils was established.Finally,the effect of the water cavity above various probes in the surface penetration was used to formulate an internal mechanism for variations in the penetration resistance factor.
基金supported by the National Natural Science Foundation of China(Nos.61735014 and 61927812)the Operation Fund of Logging Key Laboratory of Group Company(No.2021DQ0107-11)the Graduate Student Innovation Fund of Xi’an Shiyou University(Nos.YCS22213178 and YCS22213185)。
文摘A high-sensitivity low-temperature sensor based on Fabry-Pérot interferometer(FPI)is fabricated and experimentally demonstrated in this letter.The FPI air cavity is fabricated by splicing a single-mode optical fiber(SMF)with a glass capillary tube partially filled with ultraviolet(UV)glue.Due to the high coefficient of thermal expansion of UV-glue,the sensor can obtain high sensitivity.Experimental results show that the sensor has a temperature sensitivity of-3.7534 nm/℃in the temperature range of-4—4℃,and the linearity is 0.999.The engineering performance of the sensor is tested by simulating the frozen soil environment.The proposed sensor has high sensitivity and good temperature response.The sensor structure is compact and simple,low cost and has potential application in the cryogenic detection environment.
基金funding support from the National Natural Science Foundation of China(Grant No.U1934213)the National Key Research and Development Program of China(Grant Nos.2021YFB2600600 and 2021YFB2600601)。
文摘In this paper,an anisotropic critical state model for saturated soils was extended to unsaturated conditions by introducing suction into its yield function.Combining this model with soil-water characteristic curves related to porosity ratio was employed to characterize the coupled hydromechanical behavior of unsaturated anisotropic soil.Based on the plane stress condition,the problem of the cylindrical cavity expansion in unsaturated anisotropic soils was transformed into first-order differential equations using the Lagrangian description.The equations were solved as an initial value problem using the Runge-Kutta algorithm,which can reflect the soil-water retention behavior during cavity expansion.Parametric analyses were conducted to investigate the influences of overconsolidation ratio(OCR),suction,and degree of saturation on the expansion responses of a cylindrical cavity in unsaturated anisotropic soil under plane stress condition.The results show that the above factors have obvious influences on the cavity responses,and the plane strain solution tends to overestimate expansion pressure and degree of saturation but underestimates suction around the cavity compared to the proposed plane stress solution.The theoretical model proposed in this paper provides a reasonable and effective method for simulating pile installation and soil pressure gauge tests near the ground surface of the unsaturated soils.
基金funding support from the National Key Research and Development Program of China(Grant No.2023YFB2604004)the National Natural Science Foundation of China(Grant No.52108374)the“Taishan”Scholar Program of Shandong Province,China(Grant No.tsqn201909016)。
文摘The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.
文摘Based on the generally adopted soil model for engineering, an analytic solution of spherical wave propagation problem in a special case for an equally pressurized spherical cavity in saturated space by Laplace transformation which is compared with that of the same problem in a one-phase elastic space. The influence of fluid on dynamic response of saturated soil is examined. The authors propose an effective way for dynamic analysis of underground structure.
基金supported by the National Natural Science Foundation of China(Grant No.52070165)the Major Science and Technology Project of Zhejiang Province,China(Grant No.2015C03015).
文摘Jets caused by burst tubes erode the surrounding soil, eventually leading to issues such as ground collapse. It is therefore highly important to study the mechanisms of soil erosion caused by jets after pipeline leakage. To investigate the water-soil interaction mechanisms of pipe leakage, this study used transparent soil and developed a three-dimensional experimental device to observe the fluidization process. Changes in the boundary of the fluidization transition area were investigated, and a formula for calculating the soil damage area was derived. The results showed three different shapes of the fluidized cavity appearing in the fluidization process. The particles initially moved upward and then gradually transitioned into a state of backflow. The effects of particle size, upper load, and porosity on fluidization were also analyzed. It was found that soil with a large particle size and a lower porosity under a heavy upper load can effectively restrain fluidization. Therefore, large-diameter and dense soil can be used as pipe-covering material.
基金the financial support provided by the National Natural Science Foundation of China(Grant No.U1934213)the National Key Research and Development Program of China(Grant Nos.2021YFB2600601 and 2021YFB2600600).
文摘This paper presents an undrained semi-analytical elastoplastic solution for cylindrical cavity expansion in anisotropic soil under the biaxial stress conditions.The advanced simplified SANICLAY model is used to simulate the elastoplastic behavior of soil.The cavity expansion is treated as an initial value problem and solved as a system of eight first-order ordinary differential equations including four stress components and four anisotropic parameters.The results are validated by comparing the new solutions with existing ones.The distributions of stress components and anisotropic parameters around the cavity wall,the expansion process,the stress yield trajectory of a soil element and the shape and size of elastoplastic boundary are further investigated to explore the cavity expansion response of soils under biaxial in situ stresses.The results of extensive parameters analysis demonstrate that the circumferential position of the soil element and the anisotropy of the soils have noticeable impacts on the expansion response under biaxial in situ stresses.Since the present solution not only considers the anisotropy and anisotropy evolution of natural soil,but also eliminates the conventional assumption of uniform radial pressure,the solution is better than other theoretical solutions to explain the pressure test and pile installation effect of shallow saturated soil.
