Geotechnical Characteristics of Volcanic Beach Sands with Varying Iron Contents

One of the distinguishing features of volcanic beach sand compared to typical silica sand can be found in its relatively high iron content; however, studies on the effect of iron content on the engineering properties of volcanic beach sand have been very limited until now. Consequently, this experimental investigation quantifies the effect of iron content on the engineering properties of Ulleung volcanic beach sands, including small strain stiffness, compressibility, friction angle, and cone tip resistance. Various geotechnical experiments were performed, and test results demonstrate that the small strain stiffness increases with an increase in iron content because of the increased interparticle contact stiffness. In addition, the elastic deformation of soil particles decreases with an increase in iron content because of the greater elastic modulus of iron compared to that of silica. In contrast, the effects of iron content on the intermediate strain constrained modulus and on the large strain friction angle are insignificant, and these properties are mainly determined by state variables. The relationship between the stress-normalized cone tip resistance and the state parameter of tested Ulleung sand is very similar to that on silica sands, reflecting that the effect of iron contents on the cone tip resistance is minimal.     

Gmax of Reclaimed Ground on the Western Coast of Korea Using Various Field and Laboratory Measurements

The maximum shear modulus of soil is a principal parameter for the design of earth structures under static and dynamic loads. In this study, the statistical data of the maximum shear moduli of reclaimed ground in the Songdo area on the western coast of Korea were evaluated using various field and laboratory tests, including the standard penetration test (SPT), piezocone penetration test (CPTu), self-boring pressure meter test (SBPT), down-hole seismic test (DHT), seismic piezocone penetration test (SCPTu) and resonant column test (RCT). Soils were classified variously by using a conventional unified soil classification system and classification charts for CPTu data. For the soils containing mostly sand and silt, the soil classifications using the classification charts for CPTu data show good agreement with the unified soil classification. Based on the statistical analysis on various maximum shear moduli, new site-specific empirical correlations between the shear moduli and SPT and CPTu values were proposed. Predictions of the maximum shear moduli using the proposed correlations were compared with the data obtained from the DHT, which is comparatively exact in evaluating the maximum stiffness of soils. The good agreement confirmed that the proposed correlations reasonably predicted the maximum shear moduli of soils in western coastal area of Korea.     

SPT-CPT Correlation and Its Application for Liquefaction Evaluation in China

The standard penetration test (SPT) and cone penetration test (CPT) are the two most commonly used in-situ tests. In this paper, SPT-CPT correlation is investigated using statistical and regression method based on a database of in-situ tests. Two correlation equations of the SPT N-value and the CPT cone tip resistance q_c are proposed. The equations are applied for the liquefaction potential evaluation. Three effect factors including the soil type, mean particle size, and fine content are investigated for SPT-CPT correlation. The simple correlation can be used for the preliminary site investigation with least data and information. The comprehensive one can give more accurate result with detailed data. These two correlation equations are useful for different purposes with different accuracies. The liquefaction evaluations using the proposed correlation method are compared with those from the Chinese code method. It is shown that the proposed correlation can be helpful for site investigation and geotechnical design in practice.     

利用静力触探护管进行承压水观测技术研究

利用静力触探护管,提出了一种新的承压水观测方法,通过现场试验证明该法在止水效果、孔口淤积、水位稳定时间、观测数据准确度上具有较大的优势。     

茅山东部地区第三纪两期玄武岩综合地质特征

茅山东部地区第三纪两期玄武岩 ,在岩石地层上命名为凉帽顶火山岩锥、方山火山岩锥 ,分别隶属于渐新世三垛组和中—上新世雨花台组 ,相当于两个火山旋回 ,在岩石学、岩石化学、地球化学上有一定的演化规律。两期玄武岩均属钠质碱性玄武岩系列、B类岩浆 ,原始岩浆来源于深部上地幔