An information model for highway operational risk management based on the IFC-Brick schema

With the development of highways, new technologies should be continuously introduced to improve highway traffic safety. Digital twin (DT) has been an emerging field of research in recent years. To develop a digital twin management system, a data model is essential. In the field of highway operational risk management (HORM), however, the development of data models is still in its infancy. Motivated by the concept of linked data, in this paper, we attempt to propose an information model for HORM. The main achievements of this paper include data architecture, identification and classification code methods, data interaction method, and the developed system. Based on data needs analysis, the highway information model architecture for risk management is defined as five layers: basic highway products, traffic sensors and equipment, traffic rules, traffic flow, and weather. Furthermore, according to the concepts of semantic data, these five layers can be classified into three categories: highway product data, topology data, and sensor data. Although the Industry Foundation Classes (IFC) standard and Brick schema were first proposed and applied in the building domain, some of their entities and relationships can also be applied to highways. To this end, we defined some new classes, a specific ontology, and an integrated framework for HORM. Finally, a case study was carried out. Applying such information model to highways has broad potential. It changes the file-based exchange method to the data-based one, which can promote highway data exchange and applications. The proposed information model could be of great significance for HORM.</p

Determination of OCPs and PCBs in environmental water samples by GC-DLLME optimized by Response Surface Methodology

A new sample preparation procedure to determine seven organochlorine pesticides and seven polychlorinated biphenyls in environmental water samples by using a combination of ultrasonic-assisted solvent extraction and dispersive liquid-liquid micro-extraction was established, and the extracted analytes were analyzed by gas chromatography coupled with electron capture detector. Some parameters influencing the extraction efficiency were studied and optimized utilizing response surface methodology. Under the optimum extraction conditions, the method showed wide linear ranges with r2 &gt; 0.9989 and low limits of detection and quantification between 0.16 ~ 2.17 μg/L and 0.53 ~ 7.16 μg/L, respectively. Enrichment factors (EF) were high and ranged from 63 to 116. Relative standard deviations (RSDs) for the extraction of 25 μg/L of each selected OCPs and PCBs were less than 10.2 %. The proposed method was successfully used for targets contaminations determination in different water samples. α-HCH, β-HCH and p,p’-DDE were found in lake water closed to farmland with concentrations of 2.56 μg/L, 4.44 μg/L and 4.74 μg/L, respectively, and other OCPs and PCBs were not found in the corresponding water samples. The relative recoveries of OCPs and PCBs from tap water, river water and lake water at spiking levels of 10 μg/L were in the range of 81.9 ~ 109.7 %, within a relative standard deviation of 1.7 ~ 11.8 %. The results revealed that the proposed method was well suited for the determination of trace amounts of target contaminations in liquid samples

ANALYSIS ON CONSTRUCTION DEFORMATION AND SUPPORTING STRUCTURE OF TWO-STEP AND THREESECTION EXCAVATION METHOD FOR SUPER LARGER SPAN HIGHWAY TUNNEL

The super larger span tunnel is a common form of highway reconstruction and expansionprojects in recent years. In order to determine the stability of tunnel structure of the two-step andthree-section excavation method of the III-level surrounding rock mass of the super larger spanhighway, the field test method was adopted. Relying on the Laohushan Tunnel in Jinan, Shandong,China, the deformation and the structure performance of the super larger span tunnel in III-levelsurrounding rock mass are analyzed, and the safety of the tunnel and the support structure isevaluated on this basis. The results show that the maximum settlement of the arch section of theGrade III surrounding rock section is 12.5mm, and the maximum clearance convergence is 5.8mm.Both of them are much smaller than the design reserved deformation of 80mm. The maximumpressure of the surrounding rock is 0.091MPa, showing that the force acting on the supportingstructure by surrounding rock mass is small. The inner and outer arched parts of the steel frameare subject to large stresses, and most of them are tensile stresses. The maximum stress of thesteel frame is 283 MPa, and occurs at the inner side of right arch waist. Although the local stressexceeds the yield strength of the steel (235 MPa), it does not exceed its ultimate compressivestrength of 400 MPa, and the tensile and compressive stress values of the other inner and outerparts do not exceed the yield strength. Mainly, the maximum stress appears on the left side wall,reaching 4.83 MPa, which is far less than the ultimate compressive strength of sprayed concrete(11.9 MPa). For super larger span highway tunnels, located in III-level surrounding rock mass,constructed by two-step and three-section excavation method, the initial support effectivelycontrolled the tunnel deformation, the supporting structures were fully protected and the tunnelstructure was stable. The super larger span tunnel is a common form in the road reconstructionand expansion project in recent years. In order to determine the stability of tunnel structure of thetwo steps and three excavation method of the III-level surrounding rock mass of the super largerspan highway, the field test method was adopted. Relying on the Laohushan Tunnel, thedeformation and the structure performance of the super larger span tunnel in III-level surroundingrock mass were analyzed. The results show that the maximum settlement of arch of the III-levelsurrounding rock mass is 12.5mm in super larger span highway tunnel, and the maximumclearance convergence is 5.8mm. Both of them are smaller than the design reserved deformationof 80mm. The maximum surrounding rock mass pressure is 0.091MPa, the force acting on thesupporting structure by surrounding rock mass are small. The inner and outer arched parts of the steel frame bear larger stress, and are mostly tensile stress. The maximum stress on inner side ofthe steel frame is 283 MPa, and occurs at the right arch waist. The maximum stress on the outerside of the steel frame is184 MPa, and occurs at the vault. The steel frame plays an important rolein the initial support, however the force does not reach the yield strength of the steel. The shotcreteis subjected to pressure, the maximum stress appears on the left side wall is 4.83 MPa, which ismuch smaller than the ultimate compressive strength of shotcrete of 25 MPa. So for super largerspan highway tunnels, located in III-level surrounding rock mass, constructed by two-step andthree-excavation method, the whole structure is stable

Effects of Environmental Factors on Nutrients Release at Sediment-Water Interface and Assessment of Trophic Status for a Typical Shallow Lake, Northwest China

Surface sediment and water samples were collected from Daihai Lake to study the biogeochemical characteristics of nitrogen and phosphorus, to estimate the loads of these nutrients, and to assess their effects on water quality. The contents and spatial distributions of total phosphorus (TP), total nitrogen (TN), and different nitrogen forms in sediments were analyzed. The results showed that concentrations of TN and TP in surface sediments ranged from 0.27 to 1.78 g/kg and from 558.31 to 891.29 mg/kg, respectively. Ratios of C : N ranged between 8.2 and 12.1, which indicated that nitrogen accumulated came mainly from terrestrial source. Ratios of N : P in all sampling sites were below 10, which indicated that N was the limiting nutrient for algal growth in this lake. Effects of environment factors on the release of nitrogen and phosphorus in lake sediments were also determined; high pH values could encourage the release of nitrogen and phosphorus. Modified Carlson’s trophic state index (TSIM) and comprehensive trophic state index (TSIC) were applied to ascertain the trophic classification of the studied lake, and the values of TSIM and TSIC ranged from 53.72 to 70.61 and from 47.73 to 53.67, respectively, which indicated that the Daihai Lake was in the stage of hypereutropher

Research on the Anti-Reflective Cracking Performance of a Full-Depth Asphalt Pavement

In order to analyze the anti-reflective cracking performance of a full-depth asphalt pavement and study the propagation process of a reflection crack and its influencing factors, a mechanical model of pavement structural crack analysis was established based on the ABAQUS finite element software and the extended finite element method (XFEM). Based on two different loading modes of three-point bending and direct tension, the propagation process of a reflection crack is analyzed. The results show that the anti-reflective cracking performance of a full-depth asphalt pavement is better than that of a semi-rigid base pavement structure, and the loading mode II based on direct tension is more consistent with the propagation mechanism of pavement reflection cracks, while the loading mode II is more suitable for analyzing the anti-reflective cracking performance of the pavement structure. Appropriately reducing the elastic modulus of the stress-absorbing layer can significantly improve the anti-reflective cracking performance of the full-depth asphalt pavement

Review of Intelligent Road Defects Detection Technology

Road defects are important factors affecting traffic safety. In order to improve the identification efficiency of road diseases and the pertinence of maintenance and management, intelligent detection technologies of road diseases have been developed. The problems of high cost and low efficiency of artificial inspection of road diseases are solved efficiently, and the quality of road construction is improved availably. This is not only the guarantee of highway quality but also the guarantee of people’s lives and safety. This study focuses on the intelligent detection of road disease and summarizes the commonly used detection equipment in the intelligent detection technology of road diseases, which include cameras, GPR, LiDAR, and IMU. It systematically describes the evolution and development of road disease detection technology. This study analyzes the common problems existing in road disease detection technology and proposes corresponding improvement suggestions. Finally, the development trend of road detection technology is discussed, which has practical significance for the future development of road detection technology

An information model for highway operational risk management based on the IFC-Brick schema

With the development of highways, new technologies should be continuously introduced to improve highway traffic safety. Digital twin (DT) has been an emerging field of research in recent years. To develop a digital twin management system, a data model is essential. In the field of highway operational risk management (HORM), however, the development of data models is still in its infancy. Motivated by the concept of linked data, in this paper, we attempt to propose an information model for HORM. The main achievements of this paper include data architecture, identification and classification code methods, data interaction method, and the developed system. Based on data needs analysis, the highway information model architecture for risk management is defined as five layers: basic highway products, traffic sensors and equipment, traffic rules, traffic flow, and weather. Furthermore, according to the concepts of semantic data, these five layers can be classified into three categories: highway product data, topology data, and sensor data. Although the Industry Foundation Classes (IFC) standard and Brick schema were first proposed and applied in the building domain, some of their entities and relationships can also be applied to highways. To this end, we defined some new classes, a specific ontology, and an integrated framework for HORM. Finally, a case study was carried out. Applying such information model to highways has broad potential. It changes the file-based exchange method to the data-based one, which can promote highway data exchange and applications. The proposed information model could be of great significance for HORM.</p