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This article presents a laboratory and field investigation of pull-out resistance of wood bolts in rammed earth heritages. The laboratory testing involved axial tensile tests of four grout specimens prepared in specially designed moulds using PS-F (Potassium Silicate solution-Fly ash) slurry to investigate the performance of anchors. The field testing involved pull-out tests of three wood anchors installed in rammed earth heritages by gravity grouting. Experiments reveal that the failure mode is the pull-out of bolt from grout and average skin friction resistance of bolt–grout interface is approximately 0.34MPa. Load–displacement curves and elastic–residual displacement derived from cyclic loading indicate such anchor system has strong ductility with small elastic deformation and large residual deformation. Bond collapse firstly occurs at the loaded end and then propagates towards the full bonded length. Bond stress distribution is not uniform along the bonded length. Maximum bond stress distributes at the range from 0.3 m to 0.4 m. Emergence of compressive strain in the interface reveals such anchor system enjoys the advantages of both tensile and compressive anchor types, which significantly differs from results from other regular bolts. The research conclusion makes scientific senses to traditional material and craft in rammed earth heritages. [ABSTRACT FROM PUBLISHER]

The fatigue behavior of the 800H weld joint at the temperature of 800 °C was investigated, taking into account the effects of residual stress and microstructure. To model the residual stress in the welded joint, a finite element method was employed and its accuracy was verified using a hole drilling method, which was also used to study the evolution of residual stress during cutting and heating processes. Additionally, the weld region was characterized by measuring the distributions of elements and micro-hardness via energy dispersive X-ray spectroscopy and Vickers hardness tester. Fatigue lives, curves of displacement versus the number of cycles were obtained, and the fracture morphology was analyzed. The results reveal that the calculated residual stress in the weld region agrees well with the experimental results, and the transverse residual stress reduces in magnitude due to cutting and heating. Element distribution and micro-hardness exhibit obvious variations from the base metal to the weld metal. The micro-hardness has a minor effect on residual stress but a significant impact on local stress amplitudes at the weld toe. Furthermore, fatigue fractures primarily occur at the weld toe when the maximum cyclic stress exceeds 200 MPa, while the fracture location varies within the middle weld metal under smaller loads. • The low cycle fatigue behavior of 800H weld joint at high temperature of 800 °C is investigated. • The fatigue life of the weld joint is significantly inferior to that of the base metal. • Variations in properties at the weld joint prominently influence the failure location and fatigue life at the weld toe. • The distinction between the low and high fatigue regimes depends on the failure mechanism rather than the number of cycles. [ABSTRACT FROM AUTHOR]

Earthquakes occur frequently in the Loess Plateau area, which result in damage to loess due to the disturbance of multiple cyclic loading. In this paper, the historical earthquake process is simulated by pre-dynamic loading treatment on undisturbed loess samples. Then cyclic tests are carried out on these treated samples to study the later liquefaction responses with different initial water content. The undisturbed sample is relative to the remold sample instead of the samples without disturbance. Results show that the axial deformation and pore pressure ratio of treated loess samples with initial water content of 5% are larger than those without treatment. For samples with initial water content of 10% and 15%, the cycle number required for liquefaction increases after treatment, but pore pressure ratio is between 0.18 and 0.36, which is less than the 5% water content samples. It means that liquefaction will have been formed before the excess pore pressure increases to large values. Combined with microstructural analysis, it is found that pre-dynamic treatment causes earthquake damage zone in loess with water content of 5%, which results in lower liquefaction stress ratio than non-treated ones. As for samples with water content of 10% and 15%, the internal voids become smaller and fine particles move into the gaps between large particles after treatment, resulting in denser structure which is hard to be liquefied. However, the increasing dynamic stress will aggravate the deterioration of loess at the water content from 5 to 15%. The changes of microstructure of loess samples are vulnerable to the dynamic stress amplitude and water sensitivity. [ABSTRACT FROM AUTHOR]

This study examines the small-strain stress-strain properties during cyclic loading of Lanzhou loess deposits, characterized by a very high void ratio (>0.9). Torsional resonant column (RC) tests are performed in order to investigate the effect of water content, confining pressure, consolidation time and soil structure strength on the small-strain stiffness ( G 0 ) and damping (D min ) of loess. It is proved that shear modulus G 0 at low strain levels is very sensitive to water content while the effect of water content on small-strain damping D min is relatively small. As water content W approaches the plastic limit PL, there is a dramatic decrease of G 0 compared to drier loess specimen; G 0 has the tendency to reach a stable or constant value with further increase of water content which is more than the PL of loess. The small strain damping D min decreases continuously with water content for unsaturated loess and then tends to increase slightly for almost fully saturated loess. A linear relationship between G 0 and confining pressure σ′ m in log-log coordinates for different water contents is observed for Lanzhou loess. Similarly, D min decreases linearly with σ′ m . A power function is proposed to describe the relationship between G 0 and confining pressure σ′ m where the exponent m varies with the water content of loess. G 0 is also affected by the consolidation duration and a power function is proposed between normalized G 0 and normalized consolidation time. G 0 is finally strongly affected by the structure of loess and the type of specimen. For undisturbed loess samples, G 0 is always higher than reconstituted ones and the difference decreases with the degree of saturation; for fully saturated samples the influence of the structure strength between undisturbed and reconstituted samples becomes insignificant. Likewise, D min of undisturbed loess is higher than that for remolded loess under the same confining pressure and the difference between them reduces with the degree of saturation as well. [ABSTRACT FROM AUTHOR]