Experimental Study On The Anchor Performance Of Wood Bolt In Rammed Earthen Sites

Since the origin of human civilization, rammed earthen sites as an important building type continues to this today. As the carrier of history, culture, religion, and other important information, rammed earthen sites are suffering serious threats to the natural environment and human activities, remains down among the also endangered. Bolt anchor as an important measure to control the mechanical stability of rammed earthen sites, had been widely used in protection reinforcement of rammed earthen sites in the northwestern China. On the basis of meet the anchoring, gradually pay attention to explore the compatibility, the traditional wooden material had become the first choice of the anchoring reinforcement project. But on wood bolt anchoring system performance and mechanism of basic research was still in its infancy, seriously restricted the scientific application.This article chose Fraxinus chinensis roxb as rod material, potassium silicat(PS) material, calcined ginger nuts, fly ash, quartz sand and silt soil as grouting material. Laboratory model method and field experiments which consist of pullout test and strain monitoring on bolt-grout interface were conducted on wood bolts in rammed earth to study anchorage performance. Experimental results identified an indoor anchorage drawing method to simulate conditions in the field, analyzed failure mode, load and displacement relationship, strain time-histories and distribution along the bolt-grout interface. By comparing the indoor and field test results, anchorage mechanism of wooden bolt anchorage system was preliminary studied, and suitability was evaluated. Basis for the reasonable protection of earthen sites provide a scientific research.The main conclusions of this study were as follows:(1) Experimental data confirmed that the anchorage test system based on laboratory model could collect anchorage force, elastic-plastic deformation and interfacial strain at the same time. The failure mode, load-displacement curve and time-history curve of interfacial strain are studied. All results indicated that the newly developed anchorage test system model could be used as an effective research method on wooden bolt anchorage performance in rammed earthen sites, decreased damage for the rammed earthen sites.(2) Wooden bolt anchorage system showed the characteristics of the low elasticity and high plasticity, with a strong ductility, could have a result of reinforcement effect, had better compatibility on the physical and mechanical properties.(3) Wooden bolt anchorage system possessed the characteristics of tension-type bolt, as well as appeared compressive strain at anchorage end, showed both tension and pressure-type full-length bonded anchorage features.(4) Wooden bolt anchorage system and earthen sites had a good compatibility, durability and harmony with the environment, accorded with the principle of conservation, was fairly suitable to conservation of rammed earthen sites in the northwest of China.