## 2 Investigation of Subgrade Distresses in Test Area
### Evolution Process and Influencing Factors of Subgrade Distress
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Object** & **Distress Types** & **Level** & **Unit** & **Dedout Points** & **Definition** \\ \hline \multirow{4}{*}{Road shoulder} & Shoulder defects & Minor & Place & 10 & Shallow rutting or potholes less than 25 mm \\  & Shoulder defects & Severe & Place & 20 & Shallow rutting or potholes larger than or equal to 25 mm \\  & & Minor & Place & 10 & Along the trend of subgrade, the length of blocking drainage is 5-20 m. \\  & & Severe & Place & 20 & Along the trend of subgrade, the length of blocking drainage is more than 20 m \\ \cline{2-5}  & Uncleanliness & & Place & 5 & There are accumulated debris and weeks on the road shoulder \\  & & Curb defects & Place & 5 & Loss, damage, or toppling of cubs \\ \hline \multirow{4}{*}{Drainage facilities} & Blocking & Minor & Place & 5 & There are sundries and garbage in the drainage system. Every 10 m is one place, and less than 10 m is maintained \\  & & Severe & Place & 10 & The full cross-section of the drainage system is blocked, every 10 m is one place, and less than 10 m is maintained \\ \cline{2-5}  & Damaged & & Place & 5 & The lining spalling damage and masonry body cracking occurred \\ \cline{2-5}  & Inadequate drainage & & & & \\ facilities & & Km & 100 & One point will be deducted for every 10 m of inadequate drainage facilities, and less than 10 m is maintained \\ \hline \multirow{4}{*}{Reinforced structures} & Blockage of drainage holes & & Place & 20 & The expansion joint of the structure is used as the dividing section. When 30\% or more of the drain holes have poor ordering, it is counted as one place \\  & & Minor & Place & 10 & Partial foundation washout, wall voids, and slight cracks in supporting structures \\  & & Severe & Place & 20 & The overall cracking, including, and sliding of the retaining structure appear \\ \cline{2-5}  & Abnormal structural stress & & Place & 50 & Judging by the instability of independent reinforced structures \\ \hline \multirow{4}{*}{Embankment and roadbed} & Uneven settlement & Minor & Place & 20 & The height difference of uneven settlement is 30-50 mm \\  & & Severe & Place & 50 & The height difference of uneven settlement is greater than 50 mm \\ \cline{2-5}  & Pumping & & Place & 5 & The mud gushing out of the roadbed is one place. \\ \cline{2-5}  & Cracking and sliding & & Place & 50 & Arc-shaped cracks along the longitudinal direction of the subgrade pose a greater threat to the safety of the subgrade \\ \hline \multirow{4}{*}{Slope} & Slope erosion & Place & 20 & Guilles with a width and depth of 10 cm or more are counted as one place \\  & & Minor & Place & 20 & There are some vertical cracks in the side boundary of the slope \\ \cline{2-5}  & Cracking & Severe & Place & 50 & A tensile crack at the top of the slope \\ \cline{2-5}  & Local collapse & & Place & 50 & The rock and soil mass on the slope surface is loose and broken, resulting in local slope collapse \\ \cline{2-5}  & Rockfall & Place & 20 & The rock mass splits and peels off, causing the gravel to roll off \\ \cline{2-5}  & Landslide & & Place & 100 & The overall side of the slope causes traffic interruption \\ \hline \end{tabular}
\end{table} 
Table 1: Subgrade distresses data collection and determination of the deduction points.