Camila Nickole Fernandez-Morocho

This exploratory study investigated hot-pressed composites prepared from source-sorted, nominally HDPE-designated post-consumer plastic and screened Eucalyptus wood-processing particles at 0, 10, 20, and 30 wt.% wood content. Polymer identity was assigned from collection/sorting records, not confirmed by spectroscopy or thermal analysis. Three flexural subspecimens were sectioned from one plate for each composition; independent compression-batch replication was not established. The recorded peak nominal flexural stress decreased from 23.30 ± 1.55 MPa for the unfilled control to 21.92 ± 1.73, 18.30 ± 2.78, and 11.81 ± 0.52 MPa, respectively. Peak nominal compressive stresses were 15.78 ± 1.55, 9.16 ± 0.56, 13.05 ± 2.78, and 11.48 ± 0.91 MPa, giving a non-monotonic descriptive pattern. Relative to the unfilled control, the 10 wt.% mixture retained 94.1% of peak nominal flexural stress and 58.0% of peak nominal compressive stress; the corresponding values at 20 wt.% were 78.5% and 82.7%. A weighting sensitivity analysis shows that the preferred composition depends on the relative importance of the two loading modes. Original modulus estimates based on a fixed 10–20 N load window were excluded from engineering conclusions. The measurements describe within-campaign, specimen-level performance and do not establish standardized strength, batch reproducibility, or product suitability.

Depth-resolved mechanical responses of rooted forest soils are difficult to interpret because root properties and soil state can vary together with sampling depth. This study tested whether a common within-soil depth ordering of apparent shear-strength parameters persists across seven contrasting Andean Unified Soil Classification System (USCS) classes sampled beneath young Eucalyptus globulus at Surface (0–50 cm), Middle (50–150 cm), and Deep (150–200 cm) strata. Direct shear tests at normal stresses of 50, 100, and 200 kPa were used to fit apparent Mohr–Coulomb parameters (capp and φapp), while dry root mass content (RC) was evaluated separately; soil class was the paired blocking unit. Mean capp increased by 38.7% from Surface to Deep, and all seven soils followed the same Surface < Middle < Deep ordering (Friedman p < 0.001; Kendall W = 1.000), whereas mean RC decreased by 16.2% (Friedman p = 0.0019). In the only approximately depth-matched rooted–bare comparison, Deep-rooted capp exceeded the ≈170 cm bare reference in every soil class by 15.64 ± 1.28 kPa (exact Wilcoxon p = 0.0156). The novelty is the cross-soil paired-block demonstration that the same apparent cohesion ordering persists despite large differences in soil class, while RC follows the opposite profile. The pattern is depth-associated rather than causal because density, water state, stress history, and unmeasured root traits were not controlled independently across strata.

Vegetation-based slope stabilization is commonly evaluated from the final factor of safety, which can obscure whether an apparently favorable response reflects intrinsic slope resistance or the incremental effect of the vegetation treatment. This study tests whether the factor hierarchy associated with absolute stability differs from that associated with vegetation-induced stabilization and whether this distinction is preserved across limit equilibrium and finite element formulations. Seven fine-grained Andean soil classes, four vegetation systems, three slope geometries, and baseline and surcharge conditions were evaluated using laboratory-derived equivalent Mohr–Coulomb parameters. Each vegetated scenario was paired with an otherwise identical bare-soil reference, and the balanced numerical design was decomposed into factor and interaction contributions to variation across the investigated design space. Within the validated limit equilibrium domain, soil and geometry represented 72.1% and 26.6% of absolute stability variation, whereas species and soil × species represented 11.8% and 10.5% of relative vegetation-induced variation after normalization. Across 210 paired cases, agreement between methods was strong for absolute stability (r = 0.88; concordance coefficient = 0.83), but markedly weaker for vegetation-induced benefit. The results demonstrate a transferable distinction between the factors associated with system stability and those associated with intervention effectiveness. For engineering and restoration practice, plant selection should therefore follow site characterization and treatment-level numerical assessment, rather than a universal species ranking.

Slope instability in urban road corridors can generate cascading effects on mobility, road safety, infrastructure functionality, and local response systems. This study assessed perceived urban vulnerability to landslide-related instability along the Vía de Integración Barrial corridor in Loja, Ecuador, using a hazard sources–exposed elements–response capacity framework. A cross-sectional perception-based survey was administered to corridor users and nearby actors. From 506 collected responses, 432 valid questionnaires were retained after informed-consent and attention-check screening. Categorical and ordinal data were analyzed using descriptive statistics, Wilson confidence intervals, grouped perception-based indicators, exploratory Spearman correlations, and selected chi-square contrasts with Cramér’s V. The results showed that perceived vulnerability was closely associated with visible signs of physical deterioration, including roadway cracking, pavement subsidence, soil or mud falls, and visible runoff or seepage. In addition, 81.5% of respondents perceived landslide-related disruption during the next rainy season as likely or very likely. The most frequently prioritized interventions were drainage improvement (62.3%), slope stabilization and retaining works (43.3%), and control of unwanted water inputs (41.2%). Institutional response was perceived as weak, slow, or mainly reactive by 80.3% of respondents, while low trust in reporting channels was reported by 54.9%; responses indicating lack of knowledge about the responsible institution or reporting channel were retained separately. Broad willingness to engage in community-based monitoring reached 89.4%. The exploratory bivariate analyses indicated a consistent pattern of positive associations among perceived disruption likelihood, mobility impact, road-safety concern, institutional response, and reporting trust, without implying formal validation of a latent multidimensional construct. This study provides an applied framework for incorporating user-based evidence into slope-risk management, corridor maintenance, road-safety planning, and resilience-oriented urban governance in mountainous cities.

Vegetation-based nature-based solutions can improve shallow slope stability, yet transferring root-scale measurements to slope-scale assessment remains difficult. This study reanalyzes archived mechanical and engineering data for Salix integra used on an ecological canal embankment in northern Jiangsu Province, China. The dataset comprises 36 peak shear stress increments from constrained single-root direct shear tests conducted at four normal stresses and nine root-diameter classes, together with ten bifurcation records used for FracRoot reconstruction. Peak shear stress increment, Δτ, ranged from 2.41 to 39.28 kPa. Normal stress was the strongest statistical predictor within the clamped-end test configuration (r = 0.849, p < 0.001), whereas root diameter showed no significant unadjusted effect. The preserved FracRoot relationships were Dmax = 0.820D₀ and Dmin = 0.563D₀. An archived deterministic double-wedge calculation reported a factor-of-safety change from 0.92 to 1.14 after inclusion of aggregate root resistance. Because the separate unreinforced peak values, complete shear records, direct field root-depth measurements, planting geometry, and segment-level root-intersection calculations were not preserved, the statistical analysis is restricted to archived increments and the stability result is interpreted as an illustrative scenario rather than a verified design value. The novelty lies in transparently linking archived root-scale testing, branching architecture, and local slope-stability assessment while defining the evidence required for reproducible field-scale validation.

Plant roots can modify soil mechanical behaviour through anchorage, interlocking, and stress-transfer mechanisms; however, the magnitude of this effect is not uniform and depends on the soil matrix in which the root system develops. This study evaluates the biomechanical reinforcement induced by Chrysopogon zizanioides (L.) Roberty roots in seven contrasting Andean soil matrices classified as CL-ML, MH, CH, OH, OL, CL, and ML. Bare-soil and Vetiver-rooted specimens were compared across three depth intervals: 0.00–0.50 m, 0.50–1.50 m, and 1.50–2.00 m. Shear-strength parameters were determined through direct shear tests under controlled normal stresses of 50, 100, and 200 kPa, and the relative amplifications of apparent cohesion (Δc) and internal friction angle (Δφ) were calculated. ANOVA, Tukey HSD post hoc tests, effect-size analysis, descriptive depth-dependent regression analyses, and shear-resistance sensitivity analysis were then applied to identify soil-dependent reinforcement patterns. The results showed that the mechanical contribution of Vetiver roots was primarily controlled by soil type. The highest relative cohesion amplification was obtained in OL soil, where Δc reached 100.0%, whereas the strongest friction-angle response was observed in CH soil, with Δφ reaching 20.1%. MH soil exhibited an intermediate and technically balanced response, combining moderate cohesion gains with relevant frictional improvement. One-way ANOVA screening indicated that soil type was the main differentiating factor controlling the Vetiver-induced response, while depth had a less dominant effect. Tukey HSD comparisons confirmed that OL exhibited a distinct cohesion-amplification pattern relative to the other soil matrices. These findings indicate that C. zizanioides root reinforcement should not be interpreted as a uniform plant effect but as a soil-matrix-dependent biomechanical response governed by root–soil interaction. The initial mechanical condition of the soil, rather than root content alone, determines whether Vetiver reinforcement is expressed primarily as a cohesion gain, a friction-angle gain, or a combined response. Because the statistical evidence is screening-level owing to the absence of replication within soil–depth cells, these patterns should support soil-specific interpretation rather than be applied as universal amplification factors.

Landslides are a recurrent geohazard in Andean urban environments, where weak soils, intense seasonal rainfall, and unplanned urban expansion combine to increase slope vulnerability. In such settings, sustainable hillside management requires stabilization strategies that are both technically effective and environmentally compatible. This study evaluates the effect of root reinforcement by vetiver grass (Chrysopogon zizanioides) on slope stability in two representative soils from Loja, Ecuador: sandy silt (SM) and sandy clay (SC). A reduced-scale physical model with 30 days of root development was established, and consolidated–drained direct shear tests (ASTM D3080/D3080M-23) were performed to determine the shear strength parameters under bare and vetiver-reinforced conditions. These parameters were then incorporated into numerical slope stability analyses using Slide and PLAXIS 2D, considering three slope angles (30°, 45°, and 50°), six root-positioning configurations, and hydraulic conditions with and without a water table. Vetiver increased effective cohesion by 22.7% in sandy silt and 19.0% in sandy clay, while the internal friction angle increased by 21.8% and 12.2%, respectively. Across all modeled scenarios, vetiver produced a consistent improvement in the factor of safety. The most critical case, corresponding to sandy silt at 45° with a water table, increased from FS = 0.841 in the control condition to FS = 1.309 under the full-coverage configuration. Parametric sensitivity analysis yielded coefficients of variation between 4.97% and 7.03%, indicating a stable model response under controlled parameter perturbations. These findings support vetiver as an experimentally grounded and environmentally sustainable Nature-based Solution for slope stabilization and provide relevant evidence for sustainable management of hazard-prone urban hillsides in vulnerable Andean settings.

Expansive clay slopes are vulnerable to progressive strength loss induced by repeated wetting and drying, a mechanism that drives shallow failure in active moisture zones. Reproducing this degradation experimentally is time-consuming and resource-intensive. This study evaluates whether Fully Softened Strength (FSS) can serve as a practical substitute for five wet–dry cycles in expansive clay slope stability assessment. Direct shear tests were conducted on wet–dry-cycled and reconstituted FSS specimens across fourteen experimental water contents. Strength parameters were incorporated into homogeneous and heterogeneous limit equilibrium slope models, considering degraded layer thicknesses of 1–5 m and suspended water table conditions. Equivalence was assessed using root mean square error (RMSE), prediction bias, and physical representativeness. Five wet–dry cycles produced a dominant cohesion reduction of 70.4% with minor changes in friction angle, reaching a quasi-stationary degraded state. FSS reproduced an equivalent system response through mechanical compensation between cohesion and friction—not through equality of strength parameters—under shallow failure conditions. The best statistical fit was obtained at w = 43.5% (RMSE = 0.314); however, w = 42.0%, coinciding with the liquid limit, provided a physically more robust interpretation with near-zero bias. Equivalence was found to be valid only for normal stresses ≤ 50 kPa, representative of shallow failure depths of 1–4 m.