On the Uprooting Stability of Trees: Combined Loading Effect on Tree Stability Assessment

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Super absorbent polymer (SAP), known as a water retention agent, has a high capacity for water absorption, which can help enhance the soil structure. This paper studied the effects of SAP dosages on the root characteristics and anchorage of Amorpha fruticosa on rock slopes. The internal relationship between root growth effect and soil was discussed, and a specific reference was provided for the rational application of SAP on slopes. Using the pull-out and tensile resistance tests, we systematically studied the changes of soil properties, root distribution, root tensile strength, and root anchorage under six different SAP dosages. The results indicated that: (1) With the increase in SAP dosage, the natural soil water content and water content after 24 h of watering increased significantly, whereas the contents of TN, TP, and TK decreased dramatically. (2) With the increase in SAP dosage, the amount and length of first-order and secondary lateral roots decreased significantly, and there was no significant difference in diameter. The amount of downslope first-order and unembedded secondary lateral roots is greater than upslope. The amount of upslope embedded secondary lateral roots is greater than in downslope. (3) Tensile strength: embedded secondary root > non-embedded secondary root > first-order lateral root; upslope root > downslope root. (4) With the increase in SAP dosage, the plant anchorage drops noticeably. This study concluded that the significant addition of SAP could enhance the tensile strength of upslope embedded secondary lateral roots but would adversely affect soil nutrients, root distribution, and root anchorage. The addition of SAP in this test had no significant effect on improving slope stability. From the perspective of reinforcement capacity, we cannot blindly pursue the survival rate and other high dosage use of water retention agents to increase the risk of slope destabilization.

Unsaturated soils at high suctions are widespread in arid and semiarid areas. Test data on the mechanical behavior of unsaturated soils are scarce at high suctions. In this article, the effect of void ratio or density on the soil-water retention behavior was discussed on the basis of measured data of various compacted soils at high suctions. According to the test data, the soil-water retention behavior is independent of the dry density or void ratio over a high suction range, namely, if the water content of a soil specimen is kept constant, the suction will be constant and independent of the void ratio (deformation) at high suctions. Therefore, a simple testing method for measuring the stress-strain relations of unsaturated triaxial specimens at high suctions is proposed by combining the vapor equilibrium technique (VET) with saturated salt solutions and the triaxial shear tests at constant water contents. First, a known initial high suction is imposed on the specimen by using the VET with a saturated salt solution. Then, the specimen is triaxially sheared under a constant water content, thereby resulting in a constant high suction during triaxial shearing. The proposed testing method can substantially shorten the testing period for one triaxial test. Finally, the results of triaxial shear tests on silt, silty clay, and expansive soil at high suctions obtained by the proposed testing method are presented.

Electrical resistivity is a non-destructive, cost-effective and sensitive method to evaluate soil's physical and chemical properties. Electrical resistivity has been used widely in surface and subsurface exploration. The electrical resistivity is directly related to the subsurface geotechnical and geothermal properties like porosity, temperature, salinity and water content. Recently uses of waste material as an additive to improve the soil engineering properties are growing because of their cost-effectiveness. Cement Kiln Dust (CKD) is a waste material of the cement manufacturing process. CKD is widely used as an additive material in ground improvement to improve soil's geotechnical properties. This study is mainly focused on the effect of CKD on the electrical resistivity properties of the soil. In this study, the electrical resistivity of a natural soil slope treated with CKD and a test model in the laboratory was investigated. Besides, the effects of CKD on soil pH and electrical resistivity were studied by performing a series of tests to predict the soil's corrosivity potential. The soil was treated with 0, 5, 10 and 15% of CKD and the electrical resistivity of the soil was measured at different water contents, porosities and curing times. The results indicate that the soil's electrical resistivity increases by increasing the CKD content and curing time. Additionally, an increase in water content or porosity decreases the electrical resistivity of CKD treated soil. Furthermore, the electrical resistivity measurement is a practical method to determine the stabilized soil's geotechnical and geomechanical properties.

There is increasing effort in science to support disaster risk management (DRM) and climate change adaptation in urban environments. It is now common for research calls and projects to reference coproduction methods and science uptake goals. This paper identifies lessons for researchers, research funders, and research users wishing to enable useful, useable, and used science based on the perspectives of research users in urban planning from low- and middle-income countries. DRM-supporting science is viewed by policy actors as: complicated and poorly communicated; presenting inadequate, partial, and outdated information; misaligned with policy cycles; and costly to access and inadequately positioned to overcome the policy barriers that hinder integration of DRM into urban planning. Addressing these specific concerns points to more systematic collection and organisation of data and enhancement of supporting administrative structures to facilitate better sight of human vulnerability and its link to development decision-making and wider processes of urban risk creation.

Interactions between individuals and their environment play a vital role in uncovering the energy usage of building systems and improving human well‐being. The use of technology, such as wearable devices, enhances the study of people's perception of their surroundings and helps to comprehend the factors that influence individuals' satisfaction in both indoor and outdoor settings. Despite the growing number of publications in this field, there is still a lack of comprehensive understanding and exploitation of wearable sensing potential in urban planning and building operations. To address this gap, this research conducted a bibliometric review of 1661 scientific studies on the topic, identifying trends and areas where wearable applications for human‐centric well‐being research in the built environment are lacking. The analysis of keywords revealed a focus on the application of data analytics to process the vast amount of information collected through wearable sensors. However, the complexity of the subject necessitates cross‐disciplinary and international collaborations, which are still in their early stages due to a variety of reasons. Additionally, there is a lack of research exploring the potential of multidomain studies and long‐term monitoring. When considering outdoor environments, the use of people‐as‐sensors through wearables can significantly contribute to the development of resilient urban planning and environmental risk management in smart cities. Wearable sensing technologies offer valuable insights into people's experiences and preferences, but further research and collaboration are needed to fully harness their potential in urban planning and building operations toward the energy transition. By embracing these technologies and exploring multidomain research, more resilient and human‐centric environments could enhance well‐being of individuals in both indoor and outdoor contexts.This article is categorized under: Sustainable Energy > Energy Efficiency Cities and Transportation > Buildings

Wind damage in Japan is mainly caused by typhoons (i.e., tropical cyclones), which are characterized by intensive heavy rainfall and strong winds. In this study, we conducted tree-pulling experiments on two sites to find out whether rapidly supplied water on the soil would affect stability of root anchorage of hinoki (Chamaecyparis obtuse (Sieb. Et Zucc.) Endl.), as expected. For the experiments, we first supplied several quantities of water around the target trees, and then they were pulled down using a wire winch. On study site 1 (Kamiatago experimental forest), we applied general tree-pulling experiments (no water supply) in 2008 and six different irrigation treatments around the target trees in 2009. On study site 2 (Chiyoda experimental forest), we applied one irrigation treatment in 2009. As a result, five trees were uprooted and two were broken in 2008, and all nine trees were uprooted in 2009 on study site 1, regardless of irrigation treatment. On study site 2, two trees pulled down after 4 h of water supply were ruptured at the stem base, opposite to two trees pulled down immediately after supplying water. The water content below the root plate significantly affected root anchorage and more specifically, the maximum turning moment, stem angle at the maximum force, and stiffness index. Moreover, water inside the root plate increased root anchorage at the beginning of a tree failure process. However, it also reduced the root plate area of the hinge side. Conversely, high water content below the root plate decreased root anchorage.

Model computations on the critical combination of snow loading and windspeed for snow damage of scots pine, Norway spruce and Birch sp. at stand edge

Water use, storage and transfer in tropical bamboos

Response of seedlings of two Eucalyptus and three deciduous tree species from Ethiopia to severe water stress

Expansive (or swelling) clays are the most prolific problem soil across Southern Africa and many parts of the world. Large volume changes due to seasonal wetting and drying cause millions of dollars’ worth of damage to engineering infrastructure yearly. Soil-water retention behaviour is dependent ondensity, and determining the correct retention curve may be key for reliable design of infrastructure. Soilwater retention curves and shrinkage curves were measured for recompacted samples of a highly expansive bentonite clay from South Africa. Four samples were prepared at varying initial dry densities between approximately 1200 and 1500 kg/m3 and subjected to total suction testing in a dewpoint hygrometer. The water content of each sample was varied through wetting and drying. The sample volume was measured after each suction reading, allowing relationships between suction and void ratio, degree of saturation and water content to be determined. The relationship between gravimetric water content and suction was not significantly influenced by initial density. Degree of saturation at a given suction varied significantly according to initial density. Volume reductions of 25% to 36% from saturated to residual conditions were recorded, and samples tended to a residual void ratio of 0.35 to 0.4. The swelling clay showed propensity for maintaining high suctions (over 300 MPa at residual conditions) and hysteretic response between primary drying and wetting.

Pore structure effects on the water retention behaviour of a compacted silty sand soil subjected to drying-wetting cycles

In the past 40 years, China has experienced the largest and fastest urbanization development in the world. The infrastructure, urban environment and medical services of cities have been improved significantly. The health impacts are manifested in the decrease of the incidence of infectious diseases and the significant increase of the life span of residents. However, the development of urbanization in China has also created many problems, including the increasing pollution of urban environment such as air, water and soil, the disorderly spread of urban construction land, the fragmentation of natural ecological environment, dense population, traffic congestion and so on. With the process of urbanization and motorization, the lifestyle of urban population has changed, and the disease spectrum and the sequence of death causes have changed. Chronic noncommunicable diseases have replaced acute infectious diseases and become the primary threat to urban public health. According to the data published by the famous medical journal The LANCET on China's health care, the economic losses caused by five major non-communicable diseases (ischemic heart disease, cerebrovascular disease, diabetes mellitus, breast cancer and chronic obstructive pulmonary disease) will reach US$23 trillion between 2012 and 2030, more than twice the total GDP of China in 2015 (US$11.7 trillion). Therefore, China proposes to implement the strategy of "Healthy China" and develop the policy of "integrating health into ten thousand strategies". Integrate health into the whole process of urban and rural planning, construction and governance to form a healthy, equitable and accessible production and living environment. China is building healthy cities through the above four strategies. The main strategies from national system design to local planning are as follows. First of all, the top-level design of the country. There are two main points: one point, the formulation of the Healthy China 2030 Plan determines the first batch of 38 pilot healthy cities and practices the strategy of healthy city planning; the other point, formulate and implement the national health city policy and issue the National Healthy City. The evaluation index system evaluates the development of local work from five aspects: environment, society, service, crowd and culture, finds out the weak links in the work in time, and constantly improves the quality of healthy city construction. Secondly, the reform of territorial spatial planning. In order to adapt to the rapid development of urbanization, China urban plan promote the reform of spatial planning system, change the layout of spatial planning into the fine management of space, and promote the sustainable development of cities. To delimit the boundary line of urban development and the red line of urban ecological protection and limit the disorderly spread of urban development as the requirements of space control. The bottom line of urban environmental quality and resource utilization are studied as capacity control and environmental access requirements. The grid management of urban built environment and natural environment is carried out, and the hierarchical and classified management unit is determined. Thirdly, the practice of special planning for local health and medical distribution facilities. In order to embody the equity of health services, including health equity, equity of health services utilization and equity of health resources distribution. For the elderly population, vulnerable groups and patients with chronic diseases, the layout of community health care facilities and intelligent medical treatment are combined to facilitate the "last kilometer" service of health care. Finally, urban repair and ecological restoration design are carried out. From the perspective of people-oriented, on the basis of studying the comfortable construction of urban physical environment, human behavior and the characteristics of human needs, to tackle "urban diseases" and make up for "urban shortboard". China is building healthy cities through the above four strategies. Committed to the realization of a constantly developing natural and social environment, and can continue to expand social resources, so that people can enjoy life and give full play to their potential to support each other in the city.

The spatial distribution of thermal properties is important for the designing and monitoring of geothermal installations, therefore a non-invasive, high-resolution geophysical investigation of the thermal properties is eligible. The knowledge of the temperature dependant interrelations between relative dielectric permittivity, electric conductivity and the thermal conductivity is the basis for a geophysical investigation for shallow geothermal uses. Geotechnical properties such as water content, compaction, pore volume and mineralogy are strongly influencing the geothermal properties of soil. At the same time the geophysical properties of soil are dependant on these geotechnical properties. In this work the basically interrelations between geotechnical, geophysical and geothermal properties are presented and a geophysical investigation method of shallow geothermal systems is proposed.

This study compared the tissue water relations and seasonal changes in leaf water potential components of an evergreen tree,Morisonia americana, and two evergreen shrubs,Capparis verrucosa andC. aristiquetae, with two deciduous trees,Humboltiella arborea andLonchocarpus dipteroneurus, and the deciduous vineMansoa verrucifera. All these species coexist in a tropical dry forest in Venezuela. Leaves of the evergreen species are sclerophyllous, while those of the deciduous species are mesophytic. Leaf area to leaf weight ratios of fully mature leaves were about 75 and 170 cm2 g-1 in evergreen and deciduous species, respectively. Seasonal fluctuations of leaf water content per unit of dry weight, water potential, and turgor pressure were smaller in evergreen than in deciduous species. The analysis of tissue water relations using pressurevolume curves showed that evergreen species could develop a higher leaf turgor and lose turgor at lower leaf water potentials than deciduous species. This was related to a lower osmotic potential at full turgor in evergreen (≃-3.0 MPa)_than in deciduous (≃-2.0 MPa) species, rather than to the elastic properties of leaf tissue. The volumetric modulus of elasticity was 14 MPa in evergreen compared with 7-10 MPa in deciduous species. Thus, leaf characteristics are important in determining the drought resistance of evergreen species of this tropical dry forest.