This study investigates the response of a parent tunnel (PT) lining to volume loss and cross-passage (CP) shape and how it affects the stress redistribution and deformation of the PT lining around the opening for shallow tunnels in cohesionless soils. Three-dimensional finite-element parametric analyses were carried out using the Hardening Soil with Small Strain constitutive model simulated varying soil densities, CP/PT size ratios (0.25-0.90), PT volume-loss values (0.25-1.0%) and four CP geometries (circular, square, modified horseshoe, inverted-D). Results show that increasing PT volume loss generally reduces residual hoop stresses at CP springlines and crown/invert while producing higher longitudinal stresses at the springlines. CP shape controls stress arching: circular openings concentrate hoop stresses at the springlines, whereas square, inverted-D and modified-horseshoe shapes transfer higher stresses to crown/invert regions. CP deformations decrease with increasing PT volume loss. Among the shapes considered, square openings exhibit the largest vertical deformations, while circular openings show the least. Normalised force-moment plots are developed to guide lining reinforcement around CPs and to inform shape-specific reinforcement detailing aimed at miti-gating localised stress concentrations.
Root-reinforced soils are increasingly used in ecological slope protection, yet their mechanical behavior remains insufficiently described in current numerical modelling approaches. In this study, a hypoplastic constitutive model for root-reinforced soil is proposed. The mechanical reinforcement effect of plant root is incorporated by modifying both the critical state stress ratio and the critical void ratio as functions of root content. The proposed model is implemented within a finite element framework using an explicit integration scheme combined with a stress-correction procedure to ensure numerical stability. A series of benchmark simulations, including triaxial and direct shear tests on root-reinforced soil, are performed to validate the model performance. The applicability of the model is further evaluated through numerical simulations of rainfall-induced instability in vegetated slopes. The results indicate that the proposed approach provides a practical framework and an effective computational tool for analyzing and designing vegetated slopes.
Landslides with deep-seated clay-rich shear zones are highly susceptible to intense rainfall infiltration. Such hydrological disturbances promote pore-pressure generation within the shear zone, reducing effective stress and potentially triggering unexpected sliding. This study investigates a rainfall-induced catastrophic landslide in the Three Gorges Reservoir area through laboratory tests and numerical simulations. A series of direct shear tests were conducted under constant shear stress paths, where increased back pressure was applied to induce pore pressure and trigger instability. The results show that the shear-zone soils are prone to instability under hydrological perturbations, with the response strongly influenced by mobilised stress levels. Numerical simulations, based on a hypoplastic model calibrated with test data, further reveal that crack infiltration accelerates saturation, promotes the development of a continuous basal sliding surface. The close agreement with field evidence confirms that pore-pressure buildup is the primary driver of rainfall-induced landslide initiation and underscores the critical role of crack infiltration in accelerating failure.
Earthworms provide important ecosystem services such as plant yield increase and soil structure improvement. Soil tillage systems affect earthworm abundance, e.g., that of Lumbricus terrestris, the burrows of which can increase water infiltration. We tested the impact and mechanisms of additional L. terrestris on plant growth and soil physical parameters in Austria. At two sites, 14 individuals m-2 were inoculated under different soil tillage systems into large enclosures of 7.5 m2, to compare enhanced versus ambient numbers of L. terrestris for maize (Zea mays) followed by wheat (Triticum aestivum). Tested soil tillage systems were plough (CON, 30 cm depth), cultivator (RED; 15 cm depth) and no soil tillage (NT; 0 cm depth). The success rate of inoculation was similar between the soil tillage systems at 33-44 %. Number of middens were increased for enhancement than control and was highest for NT than RED and CON. At level enhancement, grain yield and N grain yield of maize were increased by 10; 13 % and 17; 23 % respectively for CON and RED, while wheat was unaffected, due to insufficient precipitation. At flowering of maize, topsoil moisture at site 2 was 18 % and 17 % higher for enhancement than control for CON and RED, while NT and wheat were unaffected. Soil aggregate stability was 2.7-2.9 times more stable at level enhancement than control for CON and RED for maize, respectively. It was shown that earthworms contribute to plant growth and soil fertility within a relatively short period. Increased numbers of earthworms had the highest effect on plants and soil parameters for CON and RED, which are usually considered to have a weaker soil structure than NT. Earthworms can therefore facilitate the conversion from CON and RED to NT for climate change adaptation and can improve soil fertility.
The contemporary food regime, driven by the capitalist market and nation states, is not sustainable. Different alternative food initiatives counteract its unsustainable character. Yet, what kind of food alternatives thrive in this actual market-state nexus constellation defining the food regime has become a site of contestation and depends on state politics. This article explores the role of state politics in relation to food alternatives in the post-socialist food regime in Czechia. In line with food regime approaches and drawing on critical state theory understanding of the state as a contested terrain, we use qualitative expert interviews and document analyses to identify three different political projects that support different kinds of food alternatives. Both, a liberal project driving for an international market economy and a nationalist project with its own major capital, foster food alternatives as part of “food from nowhere” in the current food regime, i.e., industrial world agriculture, and “food from here”, i.e., regional food. The alternative project builds initiatives in the sense of “food from somewhere” following agroecological principles and fostering rural development. Major conflicts are centered around the issues of agricultural subsidies favoring large-scale agricultural enterprises and transnational retail chains offering consumers in Czechia cheap and convenient food. Support from state politics is needed to make agroecological food alternatives in the sense of “food from somewhere” thrive.
