Browsing by Author "Valenzuela, M."

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    Development of a temperate rainforest zonation on the Pacific slopes of the North Patagonian Andes since-18 ka
    (2024) Moreno, P. I.; Alloway, B. V.; Valenzuela, M.; Villacis, L. A.; Villa-Martinez, R. P.
    Few studies along the western slopes of the Andes in Northwestern Patagonia (NWP: 40 degrees-44 degrees S) allow examining vegetation development through environmental gradients in latitude and elevation along a time continuum since the Last Glacial Termination (T1, -18-11 ka). This complete biostratigraphic context is necessary for assessing the sequence, timing, rates, and direction of compositional/structural changes of the former vegetation, and for deciphering their environmental drivers. Here we report palynological results from two NWP sites spaced -22 km apart on the western Andean slopes, Caleta Puelche roadside section located near sea level and Lago Reflejos at mid elevations (-800 m a.s.l.) and assess their continuous records since local ice-free conditions against other NWP sites. We find that cold-tolerant early successional trees dominated the initial stages of vegetation development in the Seno Reloncav & iacute; lowlands (-18-17 ka), followed by thermophilous shade-tolerant North Patagonian rainforest (NPRF) trees, which achieved their maxima between -17 and 15 ka at low-elevations. A spread of cold- and shade-tolerant hygrophilous NPRF conifers ensued (-14.8-13 ka) reaching similar magnitude at lowand mid-elevations, interrupted by increases in trees favored by canopy fragmentation linked to fire and explosive volcanism (-13-11 ka). Thermophilous, shade-intolerant, summer-drought tolerant Valdivian rainforest (VRF) trees increased and achieved maxima between -10 and 8 ka, most notably in the lowlands, coeval with peak abundance of the NPRF conifers Fitzroya/Pilgerodendron and Podocarpus nubigena in mid-elevation Lago Reflejos, contemporaneous with their virtual disappearance near sea level. Widespread increases in coldtolerant hygrophilous NPRF trees occurred after -8 ka, followed by mixing of NPRF and VRF elements in the lowlands after -6.3 ka with centennial-scale alternations. Inter-site and regional coherences of our findings suggest that variations in Southern Westerly Wind influence, along with disturbance regimes of natural and human origin, have driven the composition, structure, dynamics, and zonation of temperate rainforests in NWP since T1. We observe that Lago Reflejos features the highest abundance of Fitzroya cupressoides at regional scale since -12 ka, attesting to the importance of mid-elevation Andean environments for the persistence of these highly valued trees in the context of postglacial climate evolution, shifts in fire regimes, volcanic, and human disturbance in NWP.
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    Heavy Industrial Asphalt Pavements Design Using Software HIPAVE
    (PONTIFICIA UNIV CATOLICA CHILE, ESCUELA CONSTRUCCION CIVIL, 2009) Pradena, M.; Valenzuela, M.; Molina, P.
    This article discus about the heavy industrial asphalt pavements structural design, through the application of a mechanistic approach for the analysis and design. The heavy industrial pavements are principally characterized for its heavy traffic loads and a relative low number of repetitions. The current design practice is based on purely empirical principles, which have been developed for the design of roads asphalt pavements, and are not applicable for the design of heavy industrial pavements. So, this article contain a full study about the empirical - mechanistic design method, applicated on heavy industrial asphalt pavements analysis and design. Every stage of the method are described, and inputs like traffic loads, material properties and temperature distribution are characterized. A description of the software HIPAVE is presented, which is a software from Australia and was developed for heavy industrial asphalt pavements analysis and design. Also, the applicability of the method and the future research lines for to improve itself are discussed. In complement, a application example is presented, which consist in the design of a asphalt pavement structure, for a sawmill's yard located in Arauco province.
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    Project management applied to the infrastructure rehabilitation at the Universidad de Concepcion, Chile, following an m8.8 Earthquake
    (2011) Pradena, M.; Valenzuela, M.
    Although the buildings of the Universidad de Concepcion (UdeC) stood up well structurally to the effects of the earthquake on 27 February 2010 in Concepcion, Chile, diverse damage was generated in their non-structural elements. Due to the large number of university buildings (over 100 on the Concepcion Campus alone) and the need to start classes on 5 April, numerous simultaneous repair projects were generated. These were done within the national post-earthquake context and the specific context of the UdeC.