Anthropogenic activity-induced sinkholes pose a serious threat to building safety and human life nowadays.Real-time detection and early warning of sinkhole formation are a key and urgent problem in urban areas.This pa...Anthropogenic activity-induced sinkholes pose a serious threat to building safety and human life nowadays.Real-time detection and early warning of sinkhole formation are a key and urgent problem in urban areas.This paper presents an experimental study to evaluate the feasibility of fiber optic strain sensing nerves in sinkhole monitoring.Combining the artificial neural network(ANN)and particle image velocimetry(PIV)techniques,a series of model tests have been performed to explore the relationship between strain measurements and sinkhole development and to establish a conversion model from strain data to ground settlements.It is demonstrated that the failure mechanism of the soil above the sinkhole developed from a triangle failure plane to a vertical failure plane with increasing collapse volume.Meanwhile,the soil-embedded fiber optic strain sensing nerves allowed deformation monitoring of the ground soil in real time.Furthermore,the characteristics of the measured strain profiles indicate the locations of sinkholes and the associated shear bands.Based on the strain data,the ANN model predicts the ground settlement well.Additionally,micro-anchored fiber optic cables have been proven to increase the soil-to-fiber strain transfer efficiency for large deformation monitoring of ground collapse.展开更多
A new measurement technique is used to determine the settlement of bridge pile foundation and the thickness of deep compressed soft layer. The finite element Plaxis 3D foundation program is used in the analysis with a...A new measurement technique is used to determine the settlement of bridge pile foundation and the thickness of deep compressed soft layer. The finite element Plaxis 3D foundation program is used in the analysis with a proposed empirical equation to modify the input parameters represented by the soil compression modulus. The results of the numerical analysis using the proposed empirical equation provide insight to the settlement analysis of pile groups in soft clayey soils; consequently, the finite element Plaxis 3D program can be a useful tool for numerical analysis. The numerical analysis is modified by adjusting the calculation of compression modulus from those obtained under pressure between 100-200 kPa by which the results of the settlement are modified and thus matching the realistic measurements. The absolute error is 3 mm which is accepted compared with the last researches. This scenario can be applied for the similar problems in the theoretical applications of deep foundations.展开更多
地面沉降因其不易被察觉、成灾后果严重,一直都是当今危害较大的一种地质灾害问题.为了能够对地面沉降灾害做出有效预防,地面发生沉降时对土体进行位移监测尤为重要.分布式光纤传感技术因其可实现高灵敏度的分布式监测而成为获取土体沉...地面沉降因其不易被察觉、成灾后果严重,一直都是当今危害较大的一种地质灾害问题.为了能够对地面沉降灾害做出有效预防,地面发生沉降时对土体进行位移监测尤为重要.分布式光纤传感技术因其可实现高灵敏度的分布式监测而成为获取土体沉降位移信息的手段之一.在充分考虑直埋式应变传感光纤和周围土体沉降协调的基础上,运用厘米级高空间分辨率布里渊光时域分析(Brillouin optical time domain analysis,BOTDA)技术测量土体发生沉降时实验段光纤的应变分布,根据应变-位移计算模型将应变测值转换成位移信息,从而实现对土体沉降位移的测量,并与土体实际沉降位移进行了对比分析.实验结果表明,在光纤与土体耦合良好的阶段,沉降位移的实验测量结果与土体实际沉降位移之间符合较好;在光纤上布设地锚可以提高光纤与土体的耦合性能,进而获得更好的沉降监测效果;实验得到的纤-土沉降耦合变形程度划分标准可以用于定量评价沉降过程中光纤与土体的耦合程度.展开更多
基金support provided by the National Natural Science Foundation of China(Grant Nos.42225702,and 42077232)the Open Research Project Program of the State Key Laboratory of Internet of Things for Smart City(University of Macao)(Grant No.SKL-IoTSC(UM)-2021-2023/ORP/GA10/2022).
文摘Anthropogenic activity-induced sinkholes pose a serious threat to building safety and human life nowadays.Real-time detection and early warning of sinkhole formation are a key and urgent problem in urban areas.This paper presents an experimental study to evaluate the feasibility of fiber optic strain sensing nerves in sinkhole monitoring.Combining the artificial neural network(ANN)and particle image velocimetry(PIV)techniques,a series of model tests have been performed to explore the relationship between strain measurements and sinkhole development and to establish a conversion model from strain data to ground settlements.It is demonstrated that the failure mechanism of the soil above the sinkhole developed from a triangle failure plane to a vertical failure plane with increasing collapse volume.Meanwhile,the soil-embedded fiber optic strain sensing nerves allowed deformation monitoring of the ground soil in real time.Furthermore,the characteristics of the measured strain profiles indicate the locations of sinkholes and the associated shear bands.Based on the strain data,the ANN model predicts the ground settlement well.Additionally,micro-anchored fiber optic cables have been proven to increase the soil-to-fiber strain transfer efficiency for large deformation monitoring of ground collapse.
基金Project(SWJT11ZT04)supported by the Central College Foundation of ChinaProject(2008g032-A)supported by the Major Projects S&T Foundation of China’s Ministry of Railways,China
文摘A new measurement technique is used to determine the settlement of bridge pile foundation and the thickness of deep compressed soft layer. The finite element Plaxis 3D foundation program is used in the analysis with a proposed empirical equation to modify the input parameters represented by the soil compression modulus. The results of the numerical analysis using the proposed empirical equation provide insight to the settlement analysis of pile groups in soft clayey soils; consequently, the finite element Plaxis 3D program can be a useful tool for numerical analysis. The numerical analysis is modified by adjusting the calculation of compression modulus from those obtained under pressure between 100-200 kPa by which the results of the settlement are modified and thus matching the realistic measurements. The absolute error is 3 mm which is accepted compared with the last researches. This scenario can be applied for the similar problems in the theoretical applications of deep foundations.
文摘地面沉降因其不易被察觉、成灾后果严重,一直都是当今危害较大的一种地质灾害问题.为了能够对地面沉降灾害做出有效预防,地面发生沉降时对土体进行位移监测尤为重要.分布式光纤传感技术因其可实现高灵敏度的分布式监测而成为获取土体沉降位移信息的手段之一.在充分考虑直埋式应变传感光纤和周围土体沉降协调的基础上,运用厘米级高空间分辨率布里渊光时域分析(Brillouin optical time domain analysis,BOTDA)技术测量土体发生沉降时实验段光纤的应变分布,根据应变-位移计算模型将应变测值转换成位移信息,从而实现对土体沉降位移的测量,并与土体实际沉降位移进行了对比分析.实验结果表明,在光纤与土体耦合良好的阶段,沉降位移的实验测量结果与土体实际沉降位移之间符合较好;在光纤上布设地锚可以提高光纤与土体的耦合性能,进而获得更好的沉降监测效果;实验得到的纤-土沉降耦合变形程度划分标准可以用于定量评价沉降过程中光纤与土体的耦合程度.
