The quality of soil-nailing nondestructive testing application advantages
As we all known, the construction of soil-nailing belong to the concealed engineering, and now engineering anchor tensile force pull test methods due to the limitations of its own conditions, unable to fully and truly reflect the overall soil-nailing construction quality.In order to better solve the engineering defects, we need a simple economic and fast reliable method of soil-nailing quality detection , providing reliable means for construction quality control.
The construction is basically made up by the vast majority of full-length soil nail, other types of soil nail is relatively small, so, in this paper, the introduction of the method is mainly aimed at the type of full-length soil nail.
Many countries in the world is required with the currently available test means of the torque wrench and hydraulic jack pull test on a certain number of soil-nailing stress and ultimate bearing capacity test.However, the accuracy of torque wrench is not high and does not apply to full-length soil nail.Hydraulic jack tests is a time-consuming, laborious, destructive test methods.It can only to test a small number of soil nails, the more important is for longer length soil nail , generally speaking the soil nail which has 20 cm of anchorage length generally has a better quality is far greater than the strength of the soil nail itself, therefore,the soil-nailing has been pulled off before measured the ultimate bearing capacity of itself.In other words, a jack method can only detect the effective anchorage length of the anchor bolt less than 20 cm.If the anchor bolt for tunnel, anchor length is commonly 3 ~ 5 m.Therefore, it can be said that the detection method can not be applied to general engineering practice.
Basic principle of the quality nondestructive testing of soil-nailing from the exposed end of the soil nail enter a ultrasonic, and then use the same sensor to receive the waves reflected from the soil nail on the other head.Then according to the size of the amplitude of reflected wave to determine the soil-nailing anchorage quality.Anchoring quality, the better and more energy scattered to the surrounding rock and anchor the solid, so the smaller the amplitude of reflection wave.So with anchor of reflected wave amplitude and being measured standard soil-nailing reflection amplitude are compared to the soil-nailing anchorage quality.
To sum up, soil-nailing nondestructive testing technology is a very good application which can perfectly reflect the overall situation.