The Sichuan Ganzi Luding to Ya'an Shimian Expressway (Lushi Expressway), with a total length of 96.51 km and a bridge-tunnel ratio of 86%, makes this 'Red Road' that aligns with the route of the Red Army's Long March one of the expressways with the highest bridge-tunnel ratio in China.

On July 10, at the Anshun Dadu River Grand Bridge in the TJ9 section of the Lushi Expressway, heavy rainfall caused the river to surge, but several bridge piers stood firm. Not far from the bank, workers were busy with pile foundation construction.

It is reported that the TJ9 section is about 10 km long and includes control projects such as 'three tunnels, three bridges, and one interchange'. The bridge-tunnel ratio is as high as 91.1%, and a total of 735 pile foundations need to be poured. The main person in charge of the section said that currently, 196 pile foundations have been completed, far exceeding the target, and the 'skeleton' of this road has been initially set up.

Target: 735 piles

The most pile foundations to be poured on the entire line

It is understood that the Lushi Expressway is constructed to a two-way four-lane standard with a design speed of 80 km/h. It has attracted much attention not only because its route highly coincides with the Red Army's Long March route, but also because it connects the two major transportation arteries of western Sichuan, the Ya'an-Xichang and Ya'an-Kangding expressways, and is an important part of the 'Tibetan-Yi Corridor'. After completion, the travel time from Luding to Shimian will be shortened from the current 2.5 hours to about 1 hour.

'Our section is about 10 km long and has control projects of three tunnels, three bridges, and one interchange.' The TJ9 section is located outside Shimian County. Project manager Yu Xiaozhou introduced that the section includes Liyue Tunnel, Yujiagang Tunnel, Daping Tunnel, Youjiawan Grand Bridge, Mofanggou Grand Bridge, Anshun Dadu River Grand Bridge, and Anshun Interchange, requiring a total of 735 pile foundations.

In other sections of the entire line, such as the adjacent TJ10 section, there are 435 pile foundations in total; in the TJ5 section near the entrance of the famous Hailuogou Scenic Area, there are 596 pile foundations; and the TJ2 project department stationed in Lengqi Town, Luding County, has 332 pile foundations in its section. 'We are the section with the most pile foundations on the entire line.'

Why are so many pile foundations needed to build this expressway?

'Cut roads through mountains and build bridges over water.' Yu Xiaozhou explained that because the area is located in the transition zone from the Qinghai-Tibet Plateau to the Sichuan Basin, with high mountains and steep slopes, and adjacent to the Dadu River, Provincial Highway 217, and National Highway 549, the terrain conditions are extremely complex. In the TJ9 section, due to the large number of bridges and interchanges, the cast-in-place beam works are extensive, the construction procedures are complex, and the difficulty coefficient is high. 'The bridge engineering mileage accounts for more than 40% of this section, and the bridge-tunnel ratio is as high as 91.1%.'

196 completed

First set up the 'skeleton' of the road

It is understood that before July 1, the TJ9 section had exceeded the target task of '100 pile foundation pours' assigned by the group company. Currently, the actual number of pours has reached 196, and the progress is relatively advanced compared to the construction of the entire Lushi Expressway.

'This is the credit of all project department personnel.' Yu Xiaozhou mentioned that under the guidance of the 20-character management policy of Sichuan Communications Construction Group: 'Environment and safety first, plan guidance, quality first, strengthened execution, innovation-driven', the Lushi TJ9 project department has made steady progress, scientifically formulated construction plans, and used different mechanical equipment according to local conditions, mainly adopting a combination of high-power rotary drilling and percussion drilling.

For example, at the Anshun Interchange where pile foundations are concentrated, the construction site is open and the working area is wide, with good access road conditions, especially suitable for efficient operation of rotary drilling rigs. The principle of percussion drilling is that the machine lifts the hammer to a certain height and then uses the impact energy of the hammer's free fall to break the soil or rock, and circulates mud to remove debris, achieving the purpose of drilling. It is more suitable for construction in fill layers, clay layers, silt layers, mud layers, sand layers, gravel soil layers, gravel pebble layers, karst-developed rock layers, or fractured formations.

'It has already taken shape.' Following the direction of Yu Xiaozhou's finger, the reporter saw that the 196 pile foundations were growing like bamboo shoots after rain, extending along the footsteps of the Red Army's Long March.