Sources of uncertainty in liquefaction triggering procedures

Uncertainties in observed data and in processing field and laboratory tests are major concerns. Assigning reasonable coefficients of variation to the parameters in the conventional analyses indicates that a site with deterministic factors of safety of 1.5 can actually have liquefaction triggering probability above 20%. About a third of the variance comes from uncertainty in the load, which is independent of the resistance. Researchers have traditionally presented the results of case studies in the form of charts showing instances in which liquefaction did and did not occur and have developed relations to separate the two. Although the original researchers developed the separations informally, recent work has applied statistical methods. These give the sampling distributions of the observed data rather than the probability of triggering given the data. Researchers have addressed this issue using Bayesian methods, adopting non-informative priors. Published curves of liquefaction probabilities can be interpreted as likelihood ratios. Other independent work demonstrates that geological, meteorological, and historical data can be used to develop prior probabilities, so it may not be necessary to assume a non-informative prior. The actual prior can then be combined with the likelihood ratios to provide rational probabilities of liquefaction. We recommend that researchers publish their likelihood ratios and allow engineers faced with particular sites to use those to update their own priors.     

In-situ Microanalysis of Mg/Ca Ratio in Planktonic Foraminiferal Shells from the Indonesian Seas

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometer (LA-ICP-MS) provides an opportunity for us to perform in-situ microanalysis for depth profiling of elements and trace elements/Calcium ratios in calcite foraminiferal shells. In this study, Globigerinoides ruber shells were investigated with a total of 173 ablating positions from a total of 11 core top sediment samples that retrieved from the Indonesian Seas. The results showed changing compositions of Magnesium and Calcium from the inside to the outside surface for both of intra-test and inter-test. Subsequently, Mg/Ca ratios from the LA-ICP-MS microanalysis were compared with Mg/Ca ratios based on regular analyses, suggesting that LA-ICP-MS microanalysis may provide a comparatively safe and convenient way for investigating Mg/Ca ratio of planktonic foraminiferal shells with considerable reliability and accuracy.     

黔北道真沙坝铝土矿矿床地质特征

沙坝铝土矿床是实施务正道铝土矿整装勘查以来,在道真向斜构造单元内发现的第一个大型铝土矿床,矿体产于石炭系中统黄龙组(C2hn)碳酸盐岩或志留系中下统韩家店组(S1-2hj)页岩、泥岩、砂质页岩及粉砂质泥岩之上。含矿岩系厚度、沉积基底、含矿岩系埋藏深度、厚度稳定性与矿石质量及厚度有关。成因属碎屑岩系侵蚀基准面(部分为碳酸盐岩溶蚀基准面)上的古风化壳沉积型铝土矿床[1-4]。     

Development of the collision ratio to infer the time at which to begin a collision avoidance of a ship

A prior study attempted to solve the intrinsic problem of a critical collision condition including the slower ship’s dilemma by considering the maneuverability of the own ship and the International Regulations for Preventing Collisions at Sea (COLREGs). The collision ratio proposed in the previous study provided insight into the solution of the intrinsic problem, but it was not suitable as an index to determine the time at which to begin the maneuver to avoid the collision.This paper develops a collision ratio as an index that can be used to determine the time at which to begin the collision avoidance maneuver. The collision ratio is calculated by considering the maneuverability of the own ship, the COLREGs, and three virtual intrusion domains (VIDs). The validity of the inferred collision ratio is then assessed according to the dynamic characteristics of the own ship and the basic knowledge of the collision avoidance algorithm. The results indicate that the proposed collision ratio is suitable for use as a new index to determine the time at which to begin the collision avoidance maneuver.     

一种用于铀同位素比值α能谱分析的磷化膜制源新技术

研发了一种用于铀同位素比值α能谱分析的磷化膜制源新技术。试验发现,当镍镀片面积为3.14cm2,盐酸浓度为0.5mol/L,氯化钠浓度为2.5mol/L,磷酸二氢钾浓度为0.08mol/L,抗坏血酸浓度为20g/L,溶液体积为25 mL,恒温90℃,振荡速率为160次/min,振程20 mm时,磷化膜制源70min,200μg以下的铀可在镍箔上定量转化为磷化膜。与传统的电沉积制源技术相比较,应用磷化膜制源技术进行测量源制备时无需电沉积装置,制源过程简单快速,工效高,大量共存的232 Th、230 Th、226 Ra、231Pa等核素均不产生干扰,铀的全程回收率接近100%,α能谱峰分辨率较好。     

Anisotropic Drained Deformation Behavior and Shear Strength of Natural Soft Marine Clay

The deformation behavior and shear strength of soft marine clays subjected to wave or traffic loads are different from that in triaxial loading due to the changes of major principal stress direction β and intermediate principal stress coefficient b. To investigate the anisotropy affected by β and b in natural soft marine clay, a series of drained tests were conducted by hollow cylinder apparatus. The principal stress direction relative to vertical direction were maintained constant under an increasing shear stress, with fixed intermediate principal stress coefficient b. The influence of the b and β on anisotropy of typically Wenzhou intact clay is discussed. It was found that octahedral stress–strain relationships expressed anisotropy with different b and β. The friction angle and deviator stress ratio with different b and β were presented to provide guidance for engineering projects in the coastal zone.     

Geotechnical Investigations at the Dalian Offshore Airport,China

Based on the geotechnical investigation data of artificial island at Dalian Offshore Airport, the spatial distribution of the physical and mechanical properties of deposit soils was statistically analyzed. The field investigation revealed that the deposit soils could be subdivided into three strata, i.e., the top marine deposit stratum, middle marine-continental deposit stratum, and deep continental deposit stratum. Field and laboratory test results demonstrated that the marine deposit soils had high water content (31.2% < w_n < 63.10%), large void ratio (0.88 < e₀ < 1.75), low permeability (k_v < 10^?6 cm/s), flow-plastic state (I_L > 1), under consolidated (OCR < 1), high compressibility (E_s < 4 MPa), low shear strength (11.7 kPa < c_u < 43.7 kPa), and low bearing capacity (0 < f_ak < 120 kPa), they could not be used as natural foundation. The marine-continental and continental deposits were normally consolidated to over-consolidated (OCR ≥ 1), medium compressibility (4 MPa < E_s < 20 MPa), high shear strength (29.7 kPa < c_u < 73.7 kPa), and high bearing capacity (f_ak > 120 kPa). In addition, regression analysis results showed that the compression ratio was positively correlated with the natural water content, the coefficient of vertical consolidation was negatively correlated with the plasticity index, and the coefficient of vertical permeability was positively correlated with the initial void ratio. The results of the field and laboratory tests were synthesized to provide a basis for reclamation design.     

Parameterization of Sheared Entrainment in a Well-developed CBL.Part Ⅱ:A Simple Model for Predicting the Growth Rate of the CBL

Following the parameterization of sheared entrainment obtained in the companion paper, Liu et al. (2016), the present study aims to further investigate the characteristics of entrainment, and develop a simple model for predicting the growth rate of a well-developed and sheared CBL. The relative stratification, defined as the ratio of the stratification in the free atmosphere to that in the entrainment zone, is found to be a function of entrainment flux ratio (A _e). This leads to a simple expression of the entrainment rate, in which A _e needs to be parameterized. According to the results in Liu et al. (2016), A _e can be simply expressed as the ratio of the convective velocity scale in the sheared CBL to that in the shear-free CBL. The parameterization of the convective velocity scale in the sheared CBL is obtained by analytically solving the bulk model with several assumptions and approximations. Results indicate that the entrainment process is influenced by the dynamic effect, the interaction between mean shear and environmental stratification, and one other term that includes the Coriolis effect. These three parameterizations constitute a simple model for predicting the growth rate of a well-developed and sheared CBL. This model is validated by outputs of LESs, and the results show that it performs satisfactorily. Compared with bulk models, this model does not need to solve a set of equations for the CBL. It is more convenient to apply in numerical models.     

Parameterization of sheared entrainment in a well-developed CBL. Part I: Evaluation of the scheme through large-eddy simulations

The entrainment flux ratio A _e and the inversion layer (IL) thickness are two key parameters in a mixed layer model. A _e is defined as the ratio of the entrainment heat flux at the mixed layer top to the surface heat flux. The IL is the layer between the mixed layer and the free atmosphere. In this study, a parameterization of A _e is derived from the TKE budget in the firstorder model for a well-developed CBL under the condition of linearly sheared geostrophic velocity with a zero value at the surface. It is also appropriate for a CBL under the condition of geostrophic velocity remaining constant with height. LESs are conducted under the above two conditions to determine the coefficients in the parameterization scheme. Results suggest that about 43% of the shear-produced TKE in the IL is available for entrainment, while the shear-produced TKE in the mixed layer and surface layer have little effect on entrainment. Based on this scheme, a new scale of convective turbulence velocity is proposed and applied to parameterize the IL thickness. The LES outputs for the CBLs under the condition of linearly sheared geostrophic velocity with a non-zero surface value are used to verify the performance of the parameterization scheme. It is found that the parameterized A _e and IL thickness agree well with the LES outputs.     

Flood susceptibility mapping using frequency ratio and weights-of-evidence models in the Golastan Province,Iran

Flood is one of the most devastating natural disasters with socio-economic and environmental consequences. Thus, comprehensive flood management is essential to reduce the flood effects on human lives and livelihoods. The main goal of this study was to investigate the application of the frequency ratio (FR) and weights-of-evidence (WofE) models for flood susceptibility mapping in the Golestan Province, Iran. At first, a flood inventory map was prepared using Iranian Water Resources Department and extensive field surveys. In total, 144 flood locations were identified in the study area. Of these, 101 (70%) floods were randomly selected as training data and the remaining 43 (30%) cases were used for the validation purposes. In the next step, flood conditioning factors such as lithology, land-use, distance from rivers, soil texture, slope angle, slope aspect, plan curvature, topographic wetness index (TWI) and altitude were prepared from the spatial database. Subsequently, the receiver operating characteristic (ROC) curves were drawn for produced flood susceptibility maps and the area under the curves (AUCs) was computed. The final results indicated that the FR (AUC = 76.47%) and WofE (AUC = 74.74%) models have almost similar and reasonable results. Therefore, these flood susceptibility maps can be useful for researchers and planner in flood mitigation strategies.