In-Situ Dehydration Test of Shield Spoil in Mudstone and Pebble Soil Composite Stratum

Dongping Zhao,Sixun Wen,Qi He,Feng Wang,Baihao Zhang,Zhuyan Wang,Huachang Fang,Ye Qin 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1

When earth pressure balance (EPB) shield machine is driving in mudstone sand pebble composite stratum, it will produce a large amount of spoil with high water content. The high moisture content of spoil not only increases the difficulty and cost of transportation, but also easily leads to environmental pollution problems. In this paper, based on the shield tunnel project of Chengdu Metro Line 30, the hydraulic characteristic of shield spoil was tested, and on this basis, laboratory tests of shield spoil dehydration were carried out according to the designed precipitation scheme. The results show that: 1) The moisture content of the EPB shield spoil in the mudstone sand pebble composite stratum is as high as 55.2%, and its permeability coefficient is basically the same as that of silt, and the shield residue has the condition of in-situ dehydration. 2) The dehydration amount and residue moisture content of spoil in slope-type spoil pit showed a linear relationship with time, and the dehydration rate is slow and the total precipitation is less. In other schemes, the dehydration amount and water content of spoil increase rapidly in the first 24 hours and slowly in the later period. 3) Considering the total amount and speed of dehydration within 24 hours, the dehydration effect of spoil pit is ranked from high to low: 3D gravel cage wall spoil pit > 3D spoil pit with vacuum pumping > 3D permeable stone spoil pit > 3D spoil pit > Slope-type spoil pit. 4) 3D gravel cage wall spoil pit has high dewatering efficiency, and vacuum pumping can assist the discharge of water. It is recommended to use 3D gravel cage wall spoil pit and vacuum pumping scheme for on-site EPB tunnel spoil dewatering.

Selection of the Approach for Producing a Weighting Scheme for the CSR Evaluation Framework

Pin-Chao Liao,Jiawei Xue,Bingsheng Liu,Dongping Fang 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6

Corporate Social Responsibility (CSR) performance is key to project success in the construction industry. Although evaluation tools for CSR have been developed in previous studies, their weighting schemes are easily distorted by inputs from experts with different backgrounds, reducing the reliability of the benchmarking results. This study aims to identify the most suitable approach for a process-based evaluation framework of CSR management (CSR-EF) with a structurally, theoretically valid weighting scheme. The authors compared three approaches for weighting development and chose one that minimizes the heterogeneity of inputs from experts with various backgrounds (e.g., culture, profession, and education levels). The sensitivity of the weighting scheme and the metric priority, along withthe robustness of the scheme, were examined. Contractors’ CSR management was evaluated using the proposed CSR-EF and the results were cross-examined by practitioners from various backgrounds. Results indicated that the Analytic Network Process was the ideal method for developing the CSR-EF weighting scheme. The results providein sights for the development of weighting schemes for multi-criteria decision making. The proposed Equivalent Absolute Deviation (EAD) approach can also be used to examine the robustness of the weighting approach.

An Assessment Model of Owner Safety Management and its Application to Real Estate Projects

Ruipeng Tong,Chunlin Wu,Yang Li,Dongping Fang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.5

Establishing a scientific and applicative safety management assessment system is crucial in improving safety performance oforganizations. Currently, there are few studies on owners’ safety management assessment systems. Based on the behavioral-basedsafety theory, this paper explores the links among safety management system, safety management behavior, safety management stateand safety performance, which constitute an assessment model that characterizes the features of safety management. It then proposesa safety management indicator system that applies to real estate owners. The applicability and effectiveness of the system is verifiedby a four-year case study with a real estate owner. Relationships between safety management system, safety management behavior,safety management state, and their main impacting factors are obtained. Results indicate that the assessment model makes safetyevaluation clearer and demonstrates significant correlations between different safety management issues. Owners’ safetymanagement system is established and implemented favorably under the safety management assessment indicator system. This paperpresents a profound understanding of safety management assessment, in which the safety management assessment model and theindicator system is applied effectively in practice. To improve safety management level, specific theoretical and practicalimplications lead researchers and practitioners to pay more attention to safety management assessment.

A System Dynamics Model of Prevention through Design towards Eliminating Human Error

Xinlu Sun,Heap-Yih Chong,Pin-Chao Liao,Dongping Fang,Yanqing Wang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.5

Theoretically, prevention through design (PtD) is the most effective approach for eliminating human error in the field of construction. However, there is a lack of rigorous empirical analysis regarding the focal point of PtD. Hence, this research aims to develop a system dynamics model that depicts a mechanism for identifying the focal point of PtD and relevant design factors with respect to human error. Elevator installation serves as the scope of the model, and three sub-models of “cognition-behavior,” “environment-cognition,” and “design-environment” are developed. Their quantitative relationships are analyzed based on empirical data prior to the development of the system dynamics model. Subsequently, safety performance is simulated based on an eight-hour work day, and sensitivity analyses are conducted to determine the impact of each design factor on human error. This study provides insights into PtD using various design factors that can be generalized and used to develop safer designs under complex working environments.

1-(2-Pyridylazo)-2-naphthol as a synergistic additive for improving throwing power of through hole copper electronic electroplating

Lei Jin,Zhao-Yun Wang,Zhuan-Yun Cai,Jia-Qiang Yang,An-Ni Zheng,Fang-Zu Yang,De-Yin Wu,Dongping Zhan 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.125 No.-

In this work, we develop a novel 1-(2-Pyridylazo)-2-naphthol (PAN)-based acidic sulfate copper electronicelectroplating process for compact, homogeneous and conformal copper thickening of throughhole (TH). The adsorption characteristics, electrochemical properties and the interaction mechanismsof three additives (PEG, SPS and PAN) are studied in detail. Scanning electron microscope (SEM) and opticalmicroscope (OM) reveal that PAN can make the copper coating in fine grains and high throwing powerof 90.35% in TH without an overhang phenomenon. Theoretical calculations illustrate that the bindingenergies between additive molecules and copper surface decrease in the order: PAN > SPS > PEG. Cyclic voltammetry experiments at rotating rates of 1200 and 200 r/min prove that PAN itself can accelerateand weakly suppress copper electrodeposition at the center and mouth of TH, respectively. PANbehaves respectively the synergistic and antagonistic effects with PEG at the mouth and center of TH,and the weakly synergistic effects with SPS both at the mouth and center of TH. The addition of PANto the virgin make-up solution (VMS) containing PEG and SPS causes decreasing the relative electriccharge (DQ) at high and low rotating rates from 18.52 ± 0.08% to 8.25 ± 0.05%, which satisfies the closercopper electronic electroplating rate at the center and mouth of TH. The effective and complicated synergisticeffects of the additives PEG, SPS and PAN can achieve compact, homogeneous and conformal copperthickening of TH.