The process of ground vehicle dynamic gravimetry is inevitably affected by the carrier’s maneuvering acceleration,which makes the result contain a large amount of dynamic error.In this paper,we propose a dynamic erro...The process of ground vehicle dynamic gravimetry is inevitably affected by the carrier’s maneuvering acceleration,which makes the result contain a large amount of dynamic error.In this paper,we propose a dynamic error suppression method of gravimetry based on the high-precision acquisition of external velocity for compensating the horizontal error of the inertial plat-form.On the basis of platform gravity measurement,firstly,the dynamic performance of the system is enhanced by optimizing the horizontal damping network of the inertial platform and selecting its parameter.Secondly,an improved federal Kalman filtering algorithm and a fault diagnosis method are designed using strapdown inertial navigation system(SINS),odometer(OD),and laser Doppler velocimeter(LDV).Simulation validates that these methods can improve the accuracy and robustness of the external velocity acquisition.Three survey lines are selected in Tianjin,China,for the gravimetry experiments with different maneuvering levels,and the results demonstrate that after dynamic error suppression,the internal coincidence accuracies of smooth and uniform operation,obvious acceleration and deceleration operation,and high-dynamic operation are improved by 70.2%,73.6%,and 77.9%to reach 0.81 mGal,1.30 mGal,and 1.94 mGal,respectively,and the external coinci-dence accuracies during smooth and uniform operation are improved by 48.6%up to 1.66 mGal.It is shown that the pro-posed method can effectively suppress the dynamic error,and that the accuracy improvement increases with carrier maneuver-ability.However,the amount of residual error that can not be entirely eliminated increases as well,so the ground vehicle dynamic gravimetry should be maintained in the carrier for smooth and uniform operation.展开更多
A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced duri...A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.展开更多
Engineering shallow,large-span rock tunnels challenges deformation control and escalates construction costs.This study investigates the excavation compensation method(ECM)and its associated technologies to address the...Engineering shallow,large-span rock tunnels challenges deformation control and escalates construction costs.This study investigates the excavation compensation method(ECM)and its associated technologies to address these issues.Utilizing five key technologies,the ECM effectively modulates radial stress post-excavation,redistributes stress in the surrounding rock,and eliminates tensile stress at the excavation face.Pre-tensioning measures further enhance the rock’s residual strength,establishing a new stability equilibrium.Field tests corroborate the method’s effectiveness,demonstrating a crown settlement reduction of 3–8 mm,a nearly 50%decrease compared to conventional construction approaches.Additionally,material consumption and construction duration were reduced by approximately 30%–35%and 1.75 months per 100 m,respectively.Thus,the ECM represents a significant innovation in enhancing the stability and construction efficiency of large-span rock tunnels,marking a novel contribution to the engineering field.展开更多
To analyze the influence of time synchronization error,phase synchronization error,frequency synchronization error,internal delay of the transceiver system,and range error and angle error between the unit radars on th...To analyze the influence of time synchronization error,phase synchronization error,frequency synchronization error,internal delay of the transceiver system,and range error and angle error between the unit radars on the target detection performance,firstly,a spatial detection model of distributed high-frequency surface wave radar(distributed-HFSWR)is established in this paper.In this model,a method for accurate extraction of direct wave spectrum based on curve fitting is proposed to obtain accurate system internal delay and frequency synchronization error under complex electromagnetic environment background and low signal to noise ratio(SNR),and to compensate for the shift of range and Doppler frequency caused by time-frequency synchronization error.The direct wave component is extracted from the spectrum,the range estimation error and Doppler estimation error are reduced by the method of curve fitting,and the fitting accuracy of the parameters is improved.Then,the influence of frequency synchronization error on target range and radial Doppler velocity is quantitatively analyzed.The relationship between frequency synchronization error and radial Doppler velocity shift and range shift is given.Finally,the system synchronization parameters of the trial distributed-HFSWR are obtained by the proposed spectrum extraction method based on curve fitting,the experimental data is compensated to correct the shift of the target,and finally the correct target parameter information is obtained.Simulations and experimental results demonstrate the superiority and correctness of the proposed method,theoretical derivation and detection model proposed in this paper.展开更多
基金supported by the Shanxi Provincial Natural Science Basic Research Program Young Talent Project(S2019-JC-QN-2408).
文摘The process of ground vehicle dynamic gravimetry is inevitably affected by the carrier’s maneuvering acceleration,which makes the result contain a large amount of dynamic error.In this paper,we propose a dynamic error suppression method of gravimetry based on the high-precision acquisition of external velocity for compensating the horizontal error of the inertial plat-form.On the basis of platform gravity measurement,firstly,the dynamic performance of the system is enhanced by optimizing the horizontal damping network of the inertial platform and selecting its parameter.Secondly,an improved federal Kalman filtering algorithm and a fault diagnosis method are designed using strapdown inertial navigation system(SINS),odometer(OD),and laser Doppler velocimeter(LDV).Simulation validates that these methods can improve the accuracy and robustness of the external velocity acquisition.Three survey lines are selected in Tianjin,China,for the gravimetry experiments with different maneuvering levels,and the results demonstrate that after dynamic error suppression,the internal coincidence accuracies of smooth and uniform operation,obvious acceleration and deceleration operation,and high-dynamic operation are improved by 70.2%,73.6%,and 77.9%to reach 0.81 mGal,1.30 mGal,and 1.94 mGal,respectively,and the external coinci-dence accuracies during smooth and uniform operation are improved by 48.6%up to 1.66 mGal.It is shown that the pro-posed method can effectively suppress the dynamic error,and that the accuracy improvement increases with carrier maneuver-ability.However,the amount of residual error that can not be entirely eliminated increases as well,so the ground vehicle dynamic gravimetry should be maintained in the carrier for smooth and uniform operation.
基金Project(41941018)supported by the National Natural Science Foundation of China for the Special Project FundingProject(22-JKCF-08)supported by the Study on in-situ Stress Database and 3D in-situ Stress Inversion Technology of Highway Tunnel in Shanxi Province,China+1 种基金Project(2022-JKKJ-6)supported by the Study on Disaster Mechanism and NPR Anchor Cable Prevention and Control of Coal Mining Caving Subsidence in Operating Tunnel in Mountainous Area,ChinaProject(BBJ2024032)supported by the Fundamental Research Funds for the Central Universities(PhD Top Innovative Talents Fund of CUMTB),China。
文摘A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.
基金Projects(42377148,51674265)supported by the National Natural Science Foundation of ChinaProject(2018YFC0603705)supported by the National Key Research and Development Program of China。
文摘Engineering shallow,large-span rock tunnels challenges deformation control and escalates construction costs.This study investigates the excavation compensation method(ECM)and its associated technologies to address these issues.Utilizing five key technologies,the ECM effectively modulates radial stress post-excavation,redistributes stress in the surrounding rock,and eliminates tensile stress at the excavation face.Pre-tensioning measures further enhance the rock’s residual strength,establishing a new stability equilibrium.Field tests corroborate the method’s effectiveness,demonstrating a crown settlement reduction of 3–8 mm,a nearly 50%decrease compared to conventional construction approaches.Additionally,material consumption and construction duration were reduced by approximately 30%–35%and 1.75 months per 100 m,respectively.Thus,the ECM represents a significant innovation in enhancing the stability and construction efficiency of large-span rock tunnels,marking a novel contribution to the engineering field.
基金supported by the National Natural Science Foundation of China(61701140).
文摘To analyze the influence of time synchronization error,phase synchronization error,frequency synchronization error,internal delay of the transceiver system,and range error and angle error between the unit radars on the target detection performance,firstly,a spatial detection model of distributed high-frequency surface wave radar(distributed-HFSWR)is established in this paper.In this model,a method for accurate extraction of direct wave spectrum based on curve fitting is proposed to obtain accurate system internal delay and frequency synchronization error under complex electromagnetic environment background and low signal to noise ratio(SNR),and to compensate for the shift of range and Doppler frequency caused by time-frequency synchronization error.The direct wave component is extracted from the spectrum,the range estimation error and Doppler estimation error are reduced by the method of curve fitting,and the fitting accuracy of the parameters is improved.Then,the influence of frequency synchronization error on target range and radial Doppler velocity is quantitatively analyzed.The relationship between frequency synchronization error and radial Doppler velocity shift and range shift is given.Finally,the system synchronization parameters of the trial distributed-HFSWR are obtained by the proposed spectrum extraction method based on curve fitting,the experimental data is compensated to correct the shift of the target,and finally the correct target parameter information is obtained.Simulations and experimental results demonstrate the superiority and correctness of the proposed method,theoretical derivation and detection model proposed in this paper.
