China
Africa
Explore chapters and articles related to this topic
Cone factor from CPTU tests in very soft clays at the east of Mexico's valley
Published in Guido Gottardi, Laura Tonni, Cone Penetration Testing 2022, 2022
J.M. De La Rosa R., F.A. Flores López
Mexico City is located on a lacustrine plain in the Basin of Mexico that occupies an approximate area of 9,600 km2 and is located at 2,250 m above sea level. This basin remained open (exoreic) until 700,000 years ago, when extensive volcanic activity formed the Sierra de Chichinautzin, which closed the basin (Mooser, 1963) and obstructed drainage to the Balsas River. For this reason, the water was stored and gave rise to several lakes. At the foot of the mountains and due to the sudden change in the slopes of the rivers, large alluvial deposits of highly variable composition and cross-stratification are located, evidence of an erosive dynamic due to periods of intense rain. This area of the city was enabled as a flood control zone through the creation of artificial lagoons causing surface depressions by pumping. Texcoco Project (1969). The soils found in this zone correspond to very soft and saturated lacustrine clays, subject to a regional subsidence process due to the extraction of water by deep pumping. The use of CPTU is a common option to know the stratigraphic sequence for the determination of settlements magnitude.
Analysis of friction piles in consolidating soils
Published in António S. Cardoso, José L. Borges, Pedro A. Costa, António T. Gomes, José C. Marques, Castorina S. Vieira, Numerical Methods in Geotechnical Engineering IX, 2018
N. O’Riordan, A. Canavate-Grimal, S. Kumar, F. Ciruela-Ochoa
The Basin of Mexico occupies an area of 10,000 km2. The Basin is a predominately flat lacustrine plain with a typical elevation of about 2,250 m MSL. The stratigraphy in the lacustrine zone comprises typically an upper made ground and a desiccated crust, the Upper Clayey Formation (Formación Arcillosa Superior or FAS) which can be 30 m thick, a 0 to 5 m thickness of dense sands/volcanic glass known as the Hard Layer (Capa Dura or CD) followed by the Lower Clayey Formation (Formación Arcillosa Inferior or FAI) which can reach 50 m deep. Underlying the FAI a series of alluvial sand and gravels, cemented with clay and calcium carbonate called Deep Deposits (Depósitos Profundos or DP) up to 110 m deep. The FAS is an extremely soft and weak soil characterised with a typical lower bound undrained shear strength profile of Su = 7+1.05z (kPa), where z is the depth below the top of FAS unit. Further details on FAS properties can be found on Díaz Rodríguez (2003) and O’Riordan et al. (2017).
Human factors in landsliding processes of Lithuania
Published in Jan Rybář, Josef Stemberk, Peter Wagner, Landslides, 2018
R.B. Mikšys, V. Marcinkevičius, V. Mikulénas
The pit is located in the wavy landscape of lacustrine plain of Kelmė district (western Lithuania). The area of the pit is 0.274 km2, the proper stock of clay for brick production − 1.7 million m3. The cover of the deposit consists of vegetation layer and lacustrine sediments – aleurite, loamy clay and clay, which contain carbonates interlayers. The useful bed consists of the lacustrine clay of firm consistency and has 60–80% pelitic particles (<0.005 mm). The thickness of the layer -5–7 m. Two aquifers – unconfin ed and confined groundwater, occur in the hydrogeological crosssection. The groundwater table in sand is at the depth of 1–2 m from the surface. When mining, the surface is dugout and water is drained.
Conjunctive use of groundwater and surface water to reduce soil salinization in the Yinchuan Plain, North-West China
Published in International Journal of Water Resources Development, 2018
Peiyue Li, Hui Qian, Jianhua Wu
The Yinchuan Plain is a Cenozoic fault basin covered by approximately 2000 m of unconsolidated Quaternary deposits (Qian et al., 2012). Landforms in the plain begin with an inclined pluvial plain in the north-west; then the area transitions to a pluvial–alluvial plain and finally to an alluvial–lacustrine plain (Figure 1a). The inclined pluvial plain near the foot of Helan Mountain and the south-west area of the plain are covered by relatively thin Quaternary material, which forms a single phreatic aquifer (Figure 1b). Towards the east, the Quaternary deposits become thicker and support a multi-layer aquifer system, which includes a shallow phreatic aquifer and two confined aquifers within a depth of 250 m (Qian and Li, 2011). Aquifers are recharged mainly by leakage from irrigation canals, infiltration of irrigation water, percolation of floodwater during storm events, and boundary inflows. The recharge from precipitation and percolation of the Yellow River is minimal in most areas. It is estimated that leakage from irrigation canals and the infiltration of irrigation water account for over 80% of the total recharge of groundwater (Chen et al., 2016). Groundwater discharges in the area are mainly in the form of discharge to drains and to the Yellow River, as well as evaporation and artificial abstraction. Groundwater evaporation is intense in the plain, especially for the phreatic water. This accounts for nearly half of the total groundwater discharge (Chen et al., 2016). Artificial abstraction is concentrated in confined aquifers for domestic and industrial purposes, and the phreatic aquifer is rarely extracted for these purposes due to high concentrations of elements that are harmful to the human body and industrial equipment. Groundwater flows from south-west to north-east in the plain. Groundwater-level depth for the phreatic water is usually less than 3 m across the plain, except in the areas where groundwater cones are formed due to heavy exploitation of confined groundwater for domestic and industrial purposes.