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Enhanced prediction of the tire-road-interaction by considering the surface texture
Published in Xianhua Chen, Jun Yang, Markus Oeser, Haopeng Wang, Functional Pavements, 2020
After the validation of the tire model on basis of the wheel and the contact patch, it is now possible to simulate on different asphalt textures to predict the wheel forces and moments, but also to analyze the shear stress and ground pressure distribution for the design of the asphalt surface layer. As an example, Figure 7 also shows the side forces during a slip angle sweep on coarse grained asphalt. As the texture peaks are higher, the ground pressure peaks increase and the contact area within the simulated tire footprint decreases, which results in a smaller cornering stiffness and side force potential. The little high frequency excitations, which can be seen on the fine grained asphalt, do not occur on the coarse grained asphalt in the same extent. This phenomenon still needs to be investigated.
Experience of tunnel construction
Published in Ya. I. Marennyi, R.B. Zeidler, Tunnels with In-Situ Pressed Concrete Lining, 2020
In the supporting part, concrete is kept until it reaches 100% of the demoulding strength. This part of the forms may have either closed or open-ended shape, depending on the type of the static load exerted on the lining. Vertical ground pressure and the weight of the lining are the largest loads imposed. The vault of the tunnel structure is the most strained part. Shortening forms in the lower part of the tunnel cross-section brings about a substantial increase in the formwork manoeuverability. The supporting part of the forms is separated by slots into several elements. When the forms are under stress, they work as cantilever beams within the range of deformations. It facilitates turning of forms in the horizontal and the vertical direction without damaging concrete of the lining, ensures permanent abutment of forms to concrete.
The effect of the subsoil simulation on the punching resistance of footings
Published in Mohamad Al Ali, Peter Platko, Advances and Trends in Engineering Sciences and Technologies III, 2019
J. Hanzel, A. Bartók, J. Halvonik
Table Together, the results of 58 tests for specimens without transverse reinforcement tested under axis-symmetric conditions were included in the analysis. They were adapted from databases published by Ricker (2009); Siburg (2014) and by Simões (2018). The value of VRtest was determined using formula (1), where ΔVEd, red is upward force within control perimeter considered due to soil pressure σgd and Qmax is jack force when punching has occurred. The analysis was carried out under the assumption of the uniform ground pressure σgd = Qmax/Afoot where Afoot is contact area of the footing. () VRtest=Qmax−ΔVEd,red
Combined effects of traffic intensity, skid trail slope, skidder type, and soil moisture content on soil degradation in the Hyrcanian forest of Iran
Published in International Journal of Forest Engineering, 2023
Ahmad Solgi, Majid Lotfalian, Ali Akbar Rafiei, Enrico Marchi, Ulrik Ilstedt
Felling and processing activities were carried out motor-manually, using a chainsaw and axes (especially in thinning operations). Ground-based skidding operations were performed with two different rubber-tired cable skidders (Timberjack 450C and TAF E655) (Figure 1) driven with maximum load. The most important characteristics of the skidders are shown in Table 2. The total weight and the front and rear axle loads were measured using truck scales. The contact area between the ground and the tires was determined by spraying the area around the tire with paint before lifting the skidder with a hydraulic bottle jack. The “footprint” left on the ground by the paint was then outlined on a sheet of glass, transferred to paper, and measured with a planimeter. The ground pressure was then calculated as the ratio between the total axle load and the tire-soil contact area (Botta et al. 2009; Solgi et al. 2016). The study area had never been trafficked by forest machineries at the time of the experiment.
The effect of bogie track and forwarder design on rut formation in a peatland
Published in International Journal of Forest Engineering, 2021
Jari Ala-Ilomäki, Harri Lindeman, Blas Mola-Yudego, Robert Prinz, Kari Väätäinen, Bruce Talbot, Johanna Routa
Concern for soil and root disturbances through forest operations has increased in parallel to the trend toward larger, heavier, and more powerful forest machinery in the past decades (Hartanto et al. 2003; Ala-Ilomäki et al. 2011). The size and mass of machines have increased, and today the typical mass of forwarders and harvesters is close to 20 tons (Sirén et al. 2018). In addition to popular eight-wheeled harvesters and forwarders, a ten-wheeled forwarder has been introduced as a concept of a machine with lower nominal ground pressure (Ala-Ilomäki et al. 2011). In addition to vehicle mass, vehicle configuration and ground pressure play an important role. Ala-Ilomäki et al. (2011) found modern forwarders more favorable in terms of rut formation compared to a considerably lighter forwarder from the 1980s. Equipping a wheeled forwarder with bogie tracks lowers nominal ground pressure (NGP) and can reduce rut formation by up to 40% (Bygdén et al. 2003). In recent years, track development has been active, and specialized tracks have been developed for different soil conditions (Sirén et al. 2018). Previous studies have shown that the use of bogie tracks can reduce sinkage when compared to bare wheels (Gerasimov and Katarov 2010), reduce the peak loads (Labelle and Jaeger 2019) and consequently reduce rut depth (Sakai et al. 2008). Haas et al. (2016) compared rut formation caused by different tires and bogie tracks, finding 940 mm wide tires a viable possibility to reduce rut formation.