Vertical pullout tests of orchard trees for bio-inspired engineering of anchorage and foundation systems

Application of bio-inspired design in geotechnical engineering shows promise for improving the energy and material efficiency of several processes in infrastructure construction and site characterization. This project examines tree root systems for use in future bio-inspired design to improve the capacity of foundations used to support, for example, buildings and bridges. Foundation and anchorage elements used in industry are comprised almost solely of linear elements with a constant cross-sectional geometry. This functional form has remained the same for more than a century, primarily due to material availability and installation simplicity. Knowledge and understanding of the mechanisms that contribute to capacity development of natural nonlinear or branched foundation systems, such as tree root systems, could make foundation design more sustainable. The experiments described herein show that the root systems studied are 6-10 times as efficient as a conventional micropile system in developing tensile capacity on a per volume basis, with some systems displaying nearly 100 times efficiency in comparison to a conventional shallow footings. This paper explores the relationship between root system architecture and force-displacement behavior of tree root systems to better understand how to improve foundation capacity and demonstrates the potential for a more efficient use of materials and energy as compared to conventional pile and footing approaches.

[1]  T. Liang,et al.  Analysis of coupled axial and lateral deformation of roots in soil , 2018, International Journal for Numerical and Analytical Methods in Geomechanics.

[2]  T. Fourcaud,et al.  Tree stability under wind: simulating uprooting with root breakage using a finite element method. , 2014, Annals of botany.

[3]  Alexia Stokes,et al.  A generic 3D finite element model of tree anchorage integrating soil mechanics and real root system architecture. , 2007, American journal of botany.

[4]  Y. Liu,et al.  The root anchorage ability of Salix alba var. tristis using a pull-out test , 2011 .

[5]  D. Wood,et al.  Root branching affects the mobilisation of root-reinforcement in direct shear , 2019, E3S Web of Conferences.

[6]  A. R. Ennos.  The Scaling of Root Anchorage , 1993 .

[7]  Paul D. Hallett,et al.  Resistance of simple plant root systems to uplift loads. , 2010 .

[8]  P. Rognon,et al.  Pull-out capacity of tree root inspired anchors in shallow granular soils , 2014 .

[9]  Leung Fty,et al.  MECHANICAL PULL-OUT CAPACITY AND ROOT REINFORCEMENT OF FOUR NATIVE TREE AND SHRUB SPECIES ON ECOLOGICAL REHABILITATION OF ROADSIDE SLOPES IN HONG KONG , 2018 .

[10]  Paul D. Hallett,et al.  Mechanics of root-pullout from soil: A novel image and stress analysis procedure , 2007 .

[11]  D. J. Campbell,et al.  Root Extraction Force Measurements for Sitka Spruce , 1989 .

[12]  T. Fourcaud,et al.  Which root architectural elements contribute the best to anchorage of Pinus species? Insights from in silico experiments , 2017, Plant and Soil.

[13]  Alexia Stokes,et al.  Desirable plant root traits for protecting natural and engineered slopes against landslides , 2009, Plant and Soil.

[14]  L. Shao,et al.  The anatomically preserved stem Zhongmingella gen. nov. from the Upper Permian of China: evaluating the early evolution and phylogeny of the Osmundales , 2014 .

[15]  M. F. Bransby,et al.  Material stiffness, branching pattern and soil matric potential affect the pullout resistance of model root systems , 2007 .

[16]  J. Currey,et al.  The role of root system architecture and root hairs in promoting anchorage against uprooting forces in Allium cepa and root mutants of Arabidopsis thaliana. , 2002, Journal of experimental botany.

[17]  R. León,et al.  Root strength and trampling tolerance in the grass Paspalum dilatatum and the dicot Lotus glaber in flooded soil , 2006 .

[18]  T. Speck,et al.  Root anchorage of saplings and cuttings of woody pioneer species in a riparian environment , 2003 .

[19]  Alexia Stokes,et al.  Plant biomechanics in an ecological context. , 2006, American journal of botany.

[20]  D. Or,et al.  Pullout tests of root analogs and natural root bundles in soil: Experiments and modeling , 2011 .

[21]  M. Kalberer,et al.  The root–soil system of Norway spruce subjected to turning moment: resistance as a function of rotation , 2007, Plant and Soil.

[22]  T. Fourcaud,et al.  Root architecture and wind-firmness of mature Pinus pinaster. , 2005, The New phytologist.

[23]  Alexia Stokes,et al.  A numerical investigation into factors affecting the anchorage of roots in tension , 2005 .

[24]  T. Fourcaud,et al.  Analyzing key factors of roots and soil contributing to tree anchorage of Pinus species , 2018, Trees.

[25]  Alexia Stokes,et al.  An Experimental Investigation of the Resistance of Model Root Systems to Uprooting , 1996 .

[26]  P. Burlando,et al.  Influence of root characteristics and soil variables on the uprooting mechanics of Avena sativa and Medicago sativa seedlings , 2014 .