深圳地区滨海软土工程特性及加固技术

深圳地区滨海软土具有含水量大、压缩性高、强度低、承载力低以及结构性强等工程特性。通过对固结沉降理论分析,提出软土固结沉降计算应注意参数选取、超载量的确定、差异沉降等问题。针对深圳地区大面积软土工程具体条件,采用堆载预压法、抛石挤淤法以及复合地基法等技术措施进行软土加固收到良好的效果。     

Linear water-wave problem in a pond with a shallow beach

We consider the linear water-wave problem in a bounded water-basin with a shallow beach. In spite of the boundedness of the domain, the spectrum of the problem may have a continuous component, if the beach of the basin has a cuspidal form. Following the approach and methods of an earlier paper by S.A.Nazarov and the second named author, we improve the results of the citation by determining the spectrum in an open borderline case under weaker geometric assumptions.     

基于支持向量机的矿区复垦农田土壤-小麦镉含量高光谱估算

以徐州柳新矿区复垦农田土壤-小麦为研究对象,采用传统采样检测方法分析土壤-小麦中重金属镉含量,借助ASD FieldSpec 3型便携式高光谱仪测量样品反射光谱,对光谱进行加权移动平滑、一阶微分变换、包络线去除以及倒数的对数变换,据此选择具有显著相关的土壤和小麦镉污染胁迫敏感波段作为相关因子,建立基于支持向量机的矿区复垦农田土壤-小麦镉含量高光谱估测模型.结果表明:以粉煤灰和煤矸石作为充填物料的复垦场地镉含量在土壤环境质量三级标准值之下,但是其上种植的小麦镉含量均超标,受到严重的镉胁迫;建立的模型能够较理想地进行土壤-小麦镉含量估测,土壤的估测模型相关系数为0.947,小麦的估测模型相关系数为0.782.该研究为监测复垦农田土壤及作物重金属污染提供新方法,为保障矿区粮食安全提供技术手段.     

Water and salt movements in simultaneous flood-irrigation and well-drainage operations

This paper describes a new technology for solonchak soil reclamation in which surface flood irrigation of fresh water and pumped wells drainage of salty groundwater are combined. The comprehensive investigation of water and salt movement has been conducted through field test, laboratory simulation and numerical calculation. The dependence of desalination on irrigation water quantity, drainage quantity, leaching time and other parameters is obtained based on the field tests. The entire desalination process under the flood-irrigation and well-drainage operations was experimentally simulated in a vertical soil column. The water and salt movement has been numerically analyzed for both the field and laboratory conditions. The present work indicates that this new technology can greatly improve the effects of desalination. The project supported by the National Natural Science Foundation of China     

Microbiological quality of Italian beach sands

The paper deals with the potential sanitary risk of the human presence on the seaside. The levels of microbial contamination of beach sands are generally higher than those observed in the waters due to bioaccumulation phenomena. The diseases, which could be contracted through skin contact, are related to the potential infecting dose and the most widespread illnesses are a consequence of several species of fungi and bacteria inhabiting the coastline. Despite few studies have been performed to determine Guideline Values, preventive measures and health risk assessments should be considered.     

New Trends for Utilization of Rubber Wastes

Summary: The scrape rubber is difficult to recycle, since it is not thermoplastic material. Consequently, it must be converted into a powder. The scrape rubber powder can be reused via different ways: a- Reclamation The reclamation process was studied. This process converts the rubber powder into elastic-plastic materials. The obtained reclaims were introduced into NR formulations. The obtained data reveal that, 10–30% reclaimed rubber can replace virgin NR without scarifying the basic properties of the rubber vulcanizates. In such way we can gain cost reduction. b- Reuse as filler-extender The rubber powder was treated with some oxidizing agents and namely HNO₃ and H₂O₂ to modify its surface. The result of such treatment creates some functional groups such as carbonyl groups. The treated rubber powder was used as filler-extender in NR formulations. The treated rubber powder improves the tensile strength of the vulcanizates to some extent (62%). On the other hand, the treated powder was used in combinations with the classical reinforcing carbon black (HAF). The obtained results showed that, 20–40% of HAF can be replaced by the treated powder in NR mixes. The obtained vulcanizates have good physico-mechanical properties. In such way the production cost can be reduced. c- Utilization of sulfonated rubber powder as ion exchanger The rubber powder was sulfonated with Sulfuric and chlorosulfonic acids. The sulfonated product was evaluated as ion exchange resin to clear the industrial wastewater from heavy metals. The data showed that the Sodium salt form is more efficient ion exchanger than the acid form. d- Utilization in pavement The rubber powder is mixed with asphalt used in road pavement. The performance of asphalt concrete greatly depends on the particle size of the rubber powder used. The fine powder greatly improves the mechanical performance of the road pavement. The rubber powder was chemically modified. It was found that such modification had greatly improved the performance road pavement.     

OPTIMAL RESPONSES TO SHORELINE CHANGES: AN INTEGRATED ECONOMIC AND GEOLOGICAL MODEL WITH APPLICATION TO CURVED COASTS

The placement of sandy fill on an eroding beach, also known as “beach nourishment,” is a soft‐structure response to property loss often undertaken by coastal property owners. Here, we examine optimal beach nourishment along a curved shoreline with a model that couples geomorphic shoreline evolution with human responses to that evolution. The model includes the exogenous effects of shoreline recession due to sea‐level rise and the endogenous shoreline changes due to gradients in alongshore sediment transport. Human responses (nourishments) to shoreline changes that are not constant along the coast will change the shoreline curvature, thereby influencing local rates of shoreline change. We examine the net benefits of two alternative strategies to undertake soft structural responses to erosion: (i) the decisions of property owners to respond independently and (ii) the decisions of property owners to coordinate their individual responses. Under plausible parameterization, we find that a strategy to coordinate can dominate a strategy to act independently, and the benefits of coordination increase with greater shoreline curvature. This integration of economic and geological models demonstrates how feedbacks between human activities and natural processes can affect the evolution of the shoreline.     

Thermal analysis of thermoplastic elastomers based on recycled polyethylenes and ground tyre rubber

Thermal stability and phase structure of thermoplastic elastomers (TPEs) based on post-consumer materials such as recycled lowor high-density polyethylene and ground tyre rubber (GTR) were investigated by using TG, DSC and DMTA analysis. Preliminary reclamation of GTR leads to enhancement of compatibility between polyethylene matrix and dispersed GTR particles.     

UV-C Peroxymonosulfate Activation for Wastewater Regeneration: Simultaneous Inactivation of Pathogens and Degradation of Contaminants of Emerging Concern

This study explores the capability of Sulfate Radical-based Advanced Oxidation Processes (SR-AOPs) for the simultaneous disinfection and decontamination of urban wastewater. Sulfate and hydroxyl radicals in solution were generated activating peroxymonosulfate (PMS) under UV-C irradiation at pilot plant scale. The efficiency of the process was assessed toward the removal of three CECs (Trimethoprim (TMP), Sulfamethoxazole (SMX), and Diclofenac (DCF)) and three bacteria (Escherichia coli, Enterococcus spp., and Pseudomonas spp.) in actual urban wastewater (UWW), obtaining the optimal value of PMS at 0.5 mmol/L. Under such experimental conditions, bacterial concentration ≤ 10 CFU/100 mL was reached after 15 min of UV-C treatment (0.03 kJ/L of accumulative UV-C radiation) for natural occurring bacteria, no bacterial regrowth was observed after 24 and 48 h, and 80% removal of total CECs was achieved after 12 min (0.03 kJ/L), with a release of sulfate ions far from the limit established in wastewater discharge. Moreover, the inactivation of Ampicillin (AMP), Ciprofloxacin (CPX), and Trimethoprim (TMP) antibiotic-resistant bacteria (ARB) and reduction of target genes (ARGs) were successfully achieved. Finally, a harmful effect toward the receiving aquatic environment was not observed according to Aliivibrio fischeri toxicity tests, while a slightly toxic effect toward plant growth (phytotoxicity tests) was detected. As a conclusion, a cost analysis demonstrated that the process could be feasible and a promising alternative to successfully address wastewater reuse challenges.