# Discussion on the Design of Sprayed Eco-Protection for Near-Slope Roads Along Multi-Level Slopes
## 7 Original Design Scheme
### Design Comparative Analysis  
#### 7.4.1 Economic Comparative Analysis  
As shown in Table 7, the two design schemes differ in design parameters such as hairpin turns, turnaround areas, and curve radii of berms. A cost comparison analysis is conducted by calculating and summarizing the excavation and backfilling costs, spraying costs, and maintenance costs for both schemes. The detailed calculations and analytical procedures are outlined below.  
Excavation and filling Cost Calculation  
Original Design: Based on project specifications, the multi-level slope required excavation of 87,254.25 m\({}^{3}\) and filling of 7823.45 m\({}^{3}\). Market rates for excavation averaged RMB 12/m\({}^{3}\), while filling (using on-site Quaternary Upper Pleistocene slope deposits) cost RMB 4/m\({}^{3}\). Post-construction maintenance involved excavation and widening of ramp curves (\(\approx\)300.2 m\({}^{3}\)). Total cost: RMB 1,081,944.8(USD 150,270.11).  
Current Design: Due to expanded curve radii for berms and ramps, along with added turnaround areas and hairpin turns, total excavation increased to 87,955.36 m\({}^{3}\) (filling unchanged). Total cost: RMB 1,086,758.12(USD 150,938.63).  
Spraying Cost Calculation  
Original Design: Sprayers could not access Level 1 and 2 berms, requiring extended spray pipes and additional labor. Spraying costs rose to RMB 188/m\({}^{2}\) (Level 2) and RMB 205/m\({}^{2}\) (Level 1), with a total sprayed area of 11,235.9 m\({}^{2}\) (Level 1: 2699.5 m\({}^{2}\), Level 2: 3129.4 m\({}^{2}\), Level 3: 5407 m\({}^{2}\)). Total cost: RMB 2,028,472.7(USD 281,732.32).  
Current Design: Sprayers accessed all berms freely, maintaining a standard rate of RMB 164/m\({}^{2}\). Total cost: RMB 1,842,687.6(USD 255,928.83).  
Post-Construction Maintenance Cost Calculation  
Original Design: Water trucks could not access Level 1 and 2 berms, necessitating manual hose connections. Maintenance costs rose to RMB 20/m\({}^{2}\) (Level 1) and RMB 22/m\({}^{2}\) (Level 2). Total cost: RMB 203,941.8(USD 28,325.25).  
Current Design: Maintenance adhered to the original estimated rate (RMB 15/m\({}^{2}\)). Total cost: RMB 168,538.5(USD 23,408.13).  
Conduct an economic feasibility analysis on the original design and preliminary design by quantifying the impact of \(\pm\)10% fluctuations in excavation and slope protection costs.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Stake** & **X** & **Y** & **Z** & **Stake** & **X** & **Y** & **Z** \\ \hline K0+107 & 598,064.3 & 3,356,057.5 & 49.7 & K0+312 & 597,977.6 & 3,355,887.0 & 47.2 \\ K0+123 & 598,060.3 & 3,356,039.1 & 53.2 & K0+333 & 597,993.2 & 3,355,877.1 & 44.8 \\ K0+131 & 598,060.4 & 3,356,032.5 & 53.4 & K0+364 & 598,023.9 & 3,355,885.5 & 35.2 \\ K0+137 & 598,058.5 & 3,356,026.1 & 53.6 & & & & \\ \hline \end{tabular}
\end{table}
Table 6: _Cont._  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Curve Radii of** & **Curve Radii of** & **Curve Radii of** & **Cure Radii of** & **Curve Radii of** & & & & & \\
**Access Ramps** & **Radius of** & **Second-Level** & **Third-Level** & **Berm Width** & **Gradient of** & **Width of** & **Turmaround** \\
**(R1/R2/R3/)** & **Hairpin Turn** & **Berms** & **Berms** & **Berms** & **(m)** & **Access** & **Access** & **Access** \\
**R4/R5/R6 (m)** & **(Rb) (m)** & **(Rm2/Rm22)** & **(Rm33/Rm34)** & & & & & **Ramps (\%)** & **Ramps (m)** \\ \hline Original Design & - & - & 1/7 & 9/44/10/23 & 5 & - & - & - \\ Current Design & 30/25/18/35/21/12 & 20 & 14/12 & 12/44/16/23 & 5 & 12 & 5 & 12/11.5 \\ \hline \end{tabular}
\end{table}
Table 7: Comparative Analysis of Near-Slope Road Parameters.  
As shown in Table 8, while the current design incurs higher excavation costs, reductions in spraying and maintenance costs yield a total cost reduction of 6.5-8.0%. The proposed near-slope road design not only accommodates excavation equipment but also meets traffic needs for sprayers and water trucks during maintenance, eliminating additional excavation and labor costs and demonstrating economic feasibility.