## 1 Introduction  
Rutting, thermal cracking and fatigue cracking have long been regarded as serious issues confronting asphalt pavement due to increasing aggressiveness posed by huge traffic volume, heavy axle load and severe climate conditions [1]. It is widely accepted that asphalt mixture could be considered to be a viscoelastic material because its deformation relates closely to stress, time as well as temperature. Therefore, inclusion of viscoelastic theory in the permanent deformation investigation is a common practice [2; 3; 4; 5; 6].  
With the development of computing technique and the publishing of a variety of commercial finite element software, modeling permanent deformation using experimentation-based viscoelastic mechanics has been preferred by many researchers [7; 8; 9]. However, their studies focused mainly on rutting in simple road, i.e., straightaways. Actually, it was found that rutting in special roads such as long steep uphill road, sharp horizontal curve, intersections, etc., were more serious, since pavement stress in these cases seems more intricate and vehicle speed is considerably reduced [10; 11]. A case in point is that many asphalt pavements near signalized intersections in southern Nevada experienced severe rutting, according to historical documents [12]. Moreover, other investigations also verified the severity of rutting in special roads. For instance, [PERSON] presented a full-thickness rutting test to evaluate rutting performance of asphalt pavement in continuous uphill section [13]. [PERSON] et al. modeled the shear stress and vertical strain of asphalt pavement located in long steep longitudinal ramp and found that rutting in such condition was more susceptible to axle load [14]. [PERSON] et al. inspected the rutting depth of four signalized intersections in Nanjing, China and found that the deformations caused by tangential and vertical forces were more serious and their sensitivity to traffic and loading time was greatly enhanced [15]. Up to now, although some research was carried out on modeling rutting by considering both vertical and shearing load, models in these studies simply incorporated shear force caused by longitudinal slope, whereas the centrifugal action in curves was usually neglected. In addition, nowadays researchers have developed multiple materials to relieve rutting [16]. Among them, high-modulus asphalt concrete (HMAC), first developed in France, is a kind of hot asphalt mixture whose dynamic modulus (15 \({}^{\circ}\)C, 10 Hz) is greater than 14,000 MPa, and hence is more resistant to rutting than traditional asphalt mixture. To achieve huge mixture modulus several measures are frequently adopted, which involve introducing a special additive, using hard-grade bitumen and developing better aggregate blend, etc. Although some studies on the permanent deformation of this new material were reported [17; 18], this new material in rutting modeling is rarely considered.  
In response, this research simulated the permanent deformation of a HMAC pavement in a sloped and horizontally curved road by using the viscoelastic finite element method. The uniaxial static creep test was firstly performed to obtain the Burgers model parameters, which were subsequently used in the modeling. Meanwhile, adaptability of the Burgers model to the simulation was verified by simulating the creep test with ANSYS (ANSYS 2010, NASDAQ: ANSS, Canonsburg, PA, USA, 1970). Afterwards, deformation of the pavement was modeled and the effects of several factors on the deformation were analyzed based on the orthogonal design method. Particularly, a comparison between the deformations in straightaway and in sloped and curved road was made. Finally, a rutting prediction equation for HMAC pavement with sloped and curved alignment was proposed.