# Comparative Test on the Bond Damage of Steel and GFRP Bars Reinforcing Soft Rock Slopes
## 1 Introduction  
Due to the needs of the project, pits are often excavated to form slopes. Landslide disasters often occur due to the gravity of the earth and the instability of the slope itself. Therefore, engineers often take measures to strengthen the fragile slope. The reinforcement methods are often as follows: bolt reinforcement, anti-slide pile reinforcement, retaining wall reinforcement, bolt retaining wall reinforcement, pre-stressed anchor-rope lattice beam and bare slope. Bolt reinforcement is applicable to rock slope and soil slope, with high stability, low project cost and a short construction period. However, because the material of bolt has always been reinforced, it is easy to produce stress loss under the corrosion of long-term groundwater. Anti-slide pile reinforcement is widely used in the prevention and control of soil slope, but the determination of sliding surface and the selection of anti-slide pile position often become a difficult problem and bring uncertainty to engineering safety. Retaining wall reinforcement has the advantages of simple form, convenient construction, local materials and strong adaptability, so it is widely used. However, if the soil is weak, it will often consume a lot of economic cost. A bolt retaining wall has the advantagesof a light structure and cost saving and safe construction, but the construction process is complex and it requires procedures such as drilling, grorouting and the use of other supporting mechanical equipment. The pre-stressed anchor-rope lattice beam is a new type of anti-sliding retaining structure, which is widely used in slope treatment engineering with good effects, but it will still be plagued by corrosion. When the geological conditions are good and the space is sufficient, the bare slope can be adopted to save the cost. The aim of this test is to adopt bolt reinforcement which can last more than one hundred years. The durability of the anchorage system is affected by groundwater, fluctuating temperature, and other environmental factors when the traditional steel bar is used to reinforce the slope, coal mine and other projects [1; 2; 3; 4; 5; 6]. Compared with the traditional steel bars, the new Glass Fibre Reinforced Polymer (GFRP) bar has the advantages of high strength, light weight, low modulus, and corrosion resistance [7; 8; 9] and can be used to solve the durability problem of anchorage structures. The replacement of steel bars with GFRP bars has become one of the most potentially effective solutions to solve corrosion problems in geotechnical engineering [10] Therefore, more scholars have studied the durability of GFRP bars in different environments to achieve a deeper understanding of its application [11; 12; 13; 14; 15]. In addition to the durability of GFRP bars, many scholars have studied the anchorage performance of GFRP bars. [PERSON] et al. [16] studied the influence of the anchorage length, diameter, geotechnical parameters, and pre-stress on the bond performance of GFRP bars by ANSYS analysis. The bond slip relationship between GFRP and the grouting body was studied by [PERSON] et al. [17], and a new bond slip relationship model for GFRP bars was proposed. Comparative studies between steel and GFRP anchor bars were conducted by [PERSON] et al. [18], and [PERSON] et al. [19]. They compared the bond strength, failure slip, fatigue durability and other indexes (characteristics) of steel and GFRP bars through laboratory and field tests. Because of its lower elastic modulus, GFRP could better adapt to the deformation of slopes than steel bars [20; 21]. From the above available literature, the previous research did not mention the behaviour of surroundings reinforced by anchor bar and failed to form a clear conclusion on the difference in the performance of the steel and GFRP bars under the surrounding rock or soil condition. Therefore, the performance of steel and GFRP bars under the condition of argillaceous sandstone soft rock needs to be further studied.