Recently, two novel binders, one by-product-based binder named as GM and one phosphate-based binder named as KMP, have emerged that can stabilize soils spiked with mixed lead and zinc contaminants. However, field evaluations of the stabilization of actual soils that contaminated with mixed zinc (Zn) and inorganic chloride (Cl?) using GM and KMP have not been performed yet. This study presents a pilot-scale field test to evaluate the performance of GM and KMP to stabilize these inorganic contaminants in soils at two locations in an abandoned industrial plating plant site. The field soils were stabilized and cured for 1, 3, 7, and 28 days and tested for dry density, dynamic cone penetration, soil pH, and leachability. Laboratory unconfined compression tests were performed, and the relationship between unconfined compressive strength and dynamic cone penetrometer index was assessed. The results showed that the strength of both the GM- and KMP-stabilized soils after 28-day curing improved significantly, and the leached Zn and Cl? concentrations were well below the corresponding remediation limits. In general, the KMP-stabilized soil demonstrated superior performance in terms of higher dry density, unconfined compressive strength, average dynamic cone penetration resistance, lower dynamic cone penetrometer index in the early curing stage (7 days), and lower leached Zn concentration under all curing times. In contrast, the GM exhibited superior immobilization of Cl? in the contaminated soil irrespective of the curing time. The results demonstrate that GM and KMP are promising binders for treating Zn- and Cl?-contaminated soils at plating and other industry sites with similar contaminants.
An unsaturated soil is a three-phase material that is ubiquitous on the earth’s surface. The fully saturated and completely dry states are just two limiting conditions of an unsaturated soil. The state and properties of unsaturated soils can change significantly with external loads, weather conditions and groundwater level. Proper modelling of the state-dependent behaviour of unsaturated soils is crucial for analysing the performance of almost all civil engineering structures. So far, there are many unsaturated soil models and several relevant review papers in the literature. None of the existing review papers, however, focused on the state dependency of unsaturated soil behaviour. Moreover, some aspects of soil behaviour have not been reviewed, including small strain stiffness, dilatancy and stress-dependence of water retention curve. In the current review paper, the state dependency of unsaturated soil behaviour is reviewed, with a particular attention to the three missing parts. The review is carried out in a unified and relatively simple constitutive framework, which adopts a three-by-three compliance matrix to link incremental volumetric strain, deviator strain and degree of saturation to incremental mean net stress, deviator stress and suction. All of the nine variables in the proposed three-by-three compliance matrix have clear physical meanings and can be measured through compression, shearing and water retention tests. Theoretical models based on other constitutive stress variables can be also converted to this framework by matrix transformation.
Within the hydrodynamic modelling community, it is common practice to apply different modelling systems for coastal waters
and river systems. Whereas for coastal waters 3D finite difference or finite element grids are commonly used, river systems
are generally modelled using 1D networks. Each of these systems is tailored towards specific applications. Three-dimensional
coastal water models are designed to model the horizontal and vertical variability in coastal waters and are less well suited
for representing the complex geometry and cross-sectional areas of river networks. On the other hand, 1D river network models
are designed to accurately represent complex river network geometries and complex structures like weirs, barrages and dams.
A disadvantage, however, is that they are unable to resolve complex spatial flow variability. In real life, however, coastal
oceans and rivers interact. In deltaic estuaries, both tidal intrusion of seawater into the upstream river network and river
discharge into open waters play a role. This is frequently approached by modelling the systems independently, with off-line
coupling of the lateral boundary forcing. This implies that the river and the coastal model run sequentially, providing lateral
discharge (1D) and water level (3D) forcing to each other without the possibility of direct feedback or interaction between
these processes. An additional disadvantage is that due to the time aggregation usually applied to exchanged quantities, mass
conservation is difficult to ensure. In this paper, we propose an approach that couples a 3D hydrodynamic modelling system
for coastal waters (Delft3D) with a 1D modelling system for river hydraulics (SOBEK) online. This implies that contrary to
off-line coupling, the hydrodynamic quantities are exchanged between the 1D and 3D domains during runtime to resolve the real-time
exchange and interaction between the coastal waters and river network. This allows for accurate and mass conserving modelling
of complex coastal waters and river network systems, whilst the advantages of both systems are maintained and used in an optimal
and computationally efficient way. The coupled 1D–3D system is used to model the flows in the Pearl River Delta (Guangdong,
China), which are determined by the interaction of the upstream network of the Pearl River and the open waters of the South
China Sea. The highly complex upstream river network is modelled in 1D, simulating river discharges for the dry and wet monsoon
periods. The 3D coastal model simulates the flow due to the external (ocean) periodic tidal forcing, the salinity distribution
for both dry and wet seasons, as well as residual water levels (sea level anomalies) originating from the South China Sea.
The model is calibrated and its performance extensively assessed against field measurements, resulting in a mean root mean
square (RMS) error of below 6% for water levels over the entire Pearl River Delta. The model also represents both the discharge
distribution over the river network and salinity transport processes with good accuracy, resolving the discharge distribution
over the main branches of the river network within 5% of reported annual mean values and RMS errors for salinity in the range
of 2 ppt (dry season) to 5 ppt (wet season). 相似文献
A start‐up study for biohydrogen production from palm oil mill effluent (POME) is carried out in a pilot‐scale up‐flow anaerobic sludge blanket fixed‐film reactor (UASFF). A substrate with a chemical oxygen demand (COD) of 30 g L?1 is used, starting with molasses solution for 30 days and followed by a 10% v/v increment of POME/molasses ratio. At 100% POME, a hydrogen content of 80%, hydrogen production rate of 36 L H2 per day, and maximum COD removal of 48.7% are achieved. Bio‐kinetic coefficients of Monod, first‐order, Grau second‐order, and Stover‐Kincannon kinetic models are calculated to describe the performance of the system. The steady‐state data with 100% POME shows that Monod and Stover‐Kincannon models with bio‐kinetic coefficients of half‐velocity constant (Ks) of 6000 mg COD L?1, microbial decay rate (Kd) of 0.0015 per day, growth yield constant (Y) of 0.786 mg volatile suspended solids (VSS)/mg COD, specific biomass growth rate (μmax) of 0.568 per day, and substrate consumption rate of (Umax) 3.98 g/L day could be considered as superior models with correlation coefficients (R2) of 0.918 and 0.989, respectively, compared to first‐order and Grau's second‐order models with coefficients of K1 1.08 per day, R2 0.739, and K2s 1.69 per day, a = 7.0 per day, b = 0.847. 相似文献
Registering a 7.3 magnitude on the Richter scale, the 921 Chi-Chi Earthquake that struck central Taiwan on September 21, 1999
left the island nation with fragile soils, frequent floods, and debris flow, further weakening homeland resources. Taiwan’s
dense population had forced its residents to use mountain hills for agriculture and development. The 92-Flood in 2004, which
incurred vast monetary losses and human casualties, caused the government to rethink its strategy for land use. In order to
use land in a more efficient and in an eco-friendly manner, the Council for Economic Planning and Development, Executive Yuan
of the Taiwanese government proposed the “Land Recovery Strategy and Action Plan” in 2006. Its core concept was aimed at “respecting,
and adapting to, nature.” To achieve this goal, a hillside watershed management and flood mitigation policy was proposed.
Factors of safety, economy, and ecology were included in the policy. Both strategies and practical measures to be implemented
were organized in a chart for better understanding and for reference by other countries with similar conditions. 相似文献
An experimental simulation of planetary magnetospheres is being developed to investigate the formation of collisionless shocks
and their effects. Two experimental situations are considered. In both, the solar wind is simulated by laser ablation plasmas.
In one case, the “solar wind” flows across the magnetic field of a high-current discharge. In the other, a transverse magnetic
field is embedded in the plasma flow, which interacts with a conductive obstacle. The ablation plasma is created using the
“Tomcat” laser, currently emitting 5 J in a 6 ns pulse at 1 μm wavelength and irradiance above 1013 W/cm2. The “Zebra” z-pinch generator, with load current up to 1 MA and voltage up to 3.5 MV produces the magnetic fields. Hydrodynamic modeling
is used to estimate the plasma parameters achievable at the front of the plasma flow and to optimize the experiment design.
Particle-in-cell simulations reveal details of the interaction of the “solar wind” with an external magnetic field, including
flow collimation and heating effects at the stopping point. Hybrid simulations show the formation of a bow shock at the interaction
of a magnetized plasma flow with a conductor. The plasma density and the embedded field have characteristic spatial modulations
in the shock region, with abrupt jumps and fine structure on the skin depth scale. 相似文献
The galaxy population at z ≈ 6 has been the subject of intense study in recent years, culminating in the Hubble Ultra Deep Field (HUDF) – the deepest imaging survey yet. A large number of high-redshift galaxy candidates have been identified within the HUDF, but until now analysis of their properties has been hampered by the difficulty of obtaining spectroscopic redshifts for these faint galaxies. Our 'Gemini Lyman-Alpha at Reionization Era' (GLARE) project has been designed to undertake spectroscopic follow-up of faint ( z ' < 28.5) i '-drop galaxies at z ≈ 6 in the HUDF. In a previous paper we presented preliminary results from the first 7.5 h of data from GLARE. In this paper we detail the complete survey. We have now obtained 36 h of spectroscopy on a single GMOS slitmask from Gemini-South, with a spectral resolution of λ/ΔλFWHM≈ 1000 . We identify five strong Lyα emitters at z > 5.5 , and a further nine possible line emitters with detections at lower significance. We also place tight constraints on the equivalent width of Lyα emission for a further ten i '-drop galaxies and examine the equivalent width distribution of this faint spectroscopic sample of z ≈ 6 galaxies. We find that the fraction of galaxies with little or no emission is similar to that at z ≈ 3 , but that the z ≈ 6 population has a tail of sources with high rest-frame equivalent widths. Possible explanations for this effect include a tendency towards stronger line emission in faint sources, which may arise from extreme youth or low metallicity in the Lyman-break population at high redshift, or possibly a top-heavy initial mass function. 相似文献
