Construction Investment in Gansu Province: Ingenious Road Construction Waiting for Opening to Traffic — — On-the-spot Report on the Completion of the Post-disaster Recovery and Reconstruction Project

In the Xinglong River Valley, the construction site, which used to be bustling with machines, has faded from the hustle and bustle and turned into the final sprint stage. After a race with the flood season and a game with the traffic flow, S104 Mountain Torrent Disaster Recovery and Reconstruction Project of Yuzhong Xinglong Mountain Section 5.

Nowadays, the smooth roadbed and pavement are winding through the canyons, the bridge box girders are firmly in place, the gabion revetments are firmly guarding the banks of the Xinglong River, and the valley passages once damaged by mountain torrents and debris flows are revitalized. Although the main project has landed, the tasks of improving traffic safety facilities, repairing local defects, debugging drainage system, cleaning up the site and eliminating defects are still arduous, and every detail is directly related to the traffic safety, flood control efficiency and use quality after opening to traffic.

Overcome difficulties: rush the construction period and gnaw down the hard bone

of construction. "Recall that when we first entered the site, the river valley was covered with silt and rocks after the mountain torrents, and the roads were seriously damaged.". We completed dredging within a week, divided into three operation sections and started construction at multiple points. During the peak period, more than 200 builders and 23 sets of equipment fought synchronously to gnaw down the hard bone of bridge pile foundation before the main flood season. Walking on the whole road that has been formed, Nie Guangsheng, the project manager, looks back on the whole construction process and is filled with emotion. Since the commencement of the

project, monthly and quarterly progress plans have been established, and target responsibility letters have been signed with each construction team. After the construction peak period of two shifts day and night, now entering the final stage, the focus of work has shifted from large-scale civil construction to fine defect elimination, system commissioning and handover acceptance preparation.

"Finishing is not the same as relaxing. The closer we get to delivery, the more cautious we should be." Nie Guangsheng introduced that at the present stage, the project department has implemented a full-line investigation mechanism on foot, and the managers are guaranteed in sections. At the same time, it has continued to do a good job in the traffic organization of "closing while passing", retained the traffic guidance force, strictly prevented the cross-risk between the closing operation and the social traffic flow, and synchronously docked with traffic, emergency, scenic spots, traffic police and other units. Ensure that the project is built, tested and used well.

"The completion of the main body is only the first step, and many hidden parts and gaps are often easier to expose problems at the end stage." Nie Guangsheng squatted down to check the gap between the expansion joints and said, "We focus on reviewing the working status of the embedded parts of the 40-meter prefabricated box girder support, checking the monitoring data of the settlement and displacement of the high abutment, testing the drainage capacity of the foundation pit and the drainage holes of the bridge deck, and eliminating the hidden dangers of water accumulation and leakage in the later period.". For the side ditch shoulder formed by slip form construction popularized in the early stage, the alignment and compactness of the whole line shall be checked one by one, and the local small defects shall be repaired at fixed points. The volume of the protection project is huge, with more than 20,000 square gabions and concrete retaining walls all over the whole line. We check the filling of gabions, the appearance and settlement of retaining walls section by section to ensure the integrity and effectiveness of flood control and protection functions. At the same time, the construction sections of debris flow screening stones and river impact soil used locally in the early stage are reviewed to ensure that each section of the project meets the design standards and can withstand the actual test of floods in flood season. In the final stage, the technical team synchronously collates a complete set of construction changes, test and inspection, and special scheme data to build a solid technical file support for the completion acceptance.

In the K52 section, Ma Zhining, the head of quality inspection, carried out a full-line quality pull-net survey of the guardrail base, marking base and retaining wall appearance with testing tools. The "one-vote veto system" of quality inspection implemented by the project is still rigidly implemented in the final stage, and special review is carried out for traffic safety, protection and drainage projects.

"To eliminate defects at the end is to fight for eyesight and trueness." Ma Zhining, holding a record book in his hand, while marking the points that need to be rectified, said, "All the major quality problems have been dealt with in the early stage, and now we focus on the details of the corners: the depth of the guardrail column, the base of the sign, whether the drainage ditch is blocked, the surface of the concrete component is honeycombed and pitted, and the gabion is partially loose.". Establish an account for each defect, specify the rectification team and the time limit for rectification. After the rectification is completed, the sales number must be reviewed and never handed over with the problem. Raw material re-inspection records, compaction detection, bridge component detection and other data correspond to the site entity one by one, so that what the site is, what the data is, to ensure the quality of post-disaster reconstruction closed-loop. In

the river valley section, Niu Hongjin, the subgrade engineer, is leading the team to inspect and eliminate the defects of the subgrade slope, drainage ditch and retaining wall. After many rounds of rainfall tests, the roadbed and protection system that have been formed have been tested under actual working conditions.

"After the rain erosion in the rainy season, some small gullies and side ditches on the slope are the key objects we are dealing with now." Niu Hongjin introduced that at this stage, we should focus on checking the 53567 cubic meter filling and 27634 cubic meter excavation sections of the whole line, checking whether the roadbed has settlement and cracking; checking the combination of retaining walls, gabions and roadbed, dredging 3261 meters of side ditches and 325 meters of drainage canals to ensure that rainwater can be discharged smoothly and avoid water soaking the roadbed. "Roadbed protection is the first barrier against mountain torrents, before delivery, drainage and slope stability must be implemented, so as to truly restore the flood discharge capacity of the river and achieve the goal of disaster prevention and mitigation at the beginning of construction."

Tighten the line of defense: compact the responsibility and guard the safety

at the end. "At the end, safety should not be taken lightly.". There are fewer large-scale mechanical operations, but sporadic repairs, high-altitude operations, fire cutting and edge operations still exist, the traffic flow to and from the society is not interrupted for a moment, and the risk points are more dispersed and concealed. Han Jinlong, the person in charge of safety who walked and inspected along the road, carefully checked the edge protection and the setting of the remaining enclosure.

The project has not yet been completely closed for inspection, and still maintains a half-width traffic mode. Han Jinlong introduced that at the present stage, the key points of safety management and control have been optimized, scattered operation areas have been compressed, warning and protection have been set up at all operation points, full-time traffic guidance teams have been retained, and traffic command robots have been on duty continuously; hot work still strictly implements the hot work approval process. Although the large-scale flood season rescue stage has passed, the risk of rainfall in the valley is still there, four safety shelters and flood control materials are in a standing state, and the contingency plan system is not withdrawn. "Many people feel that quick delivery can be relieved, in fact, sporadic repair operations, cross-traffic environment, a little negligence is prone to accidents.". We insist on daily investigation of hidden dangers, continue to carry out pre-job reminders for workers, resolutely ensure that hidden dangers are not cleared, operations are not finished, and keep the bottom line of safety at the end of the stage.

"The paving of the main pavement has been completed, and at this stage, it is mainly the marking, the installation of guardrails, the treatment of local pavement diseases, and the smooth transition of shoulders and ancillary structures." Liu Zhian said that the temperature difference between day and night in mountainous areas is large, and there are strict requirements for the construction conditions of linear and reflective signs, so it is necessary to seize the appropriate window period for operation. The pavement and traffic safety works are completed synchronously, the signs, markings and guardrails are continuous and complete, and the road entity and safety protection are in place synchronously, so as to ensure that the road has complete and safe traffic conditions as soon as it is delivered.

"Clean up the base of the guardrail here, pull out all the gravel and debris in the corner of the side ditch, and maintain the concrete of the base of the sign in place." On the road site, Chen Kai, a construction worker, took the list of defects and ran back and forth at various scattered working points, docking with various labor teams to carry out rectification tasks. During the peak period, he stared at large-scale machinery, pouring and masonry, and entered the end. His work turned into running all over the whole line at every marked point, urging rectification, checking the site and cleaning up construction waste.

"Work hard to make progress, and be careful in the final stage." Chen Kai wiped the sweat on his forehead. "In the past, two shifts grabbed the pile foundation, but now they walk back and forth along the road of more than 5 kilometers. Every small problem marked on the account should be focused on until the rectification is completed.". We should also do a good job of site cleaning, remove construction waste and construction waste from the site, and return the clean and tidy road environment to the valley. Although tired, but think of this road will soon be handed over to the people, to the scenic spot, the heart is quite a sense of achievement."

Along the Xinglong River, the scars of mountains and rivers once torn by mountain torrents are being healed one by one in the hands of builders.". After overcoming difficulties, the post-disaster reconstruction project of S104 Yuzhong Xinglongshan Section is about to be delivered. This road is not only a highway, but also protects the safety of people's lives and property along the road. It connects the red positions of Xinglongshan Martyrs Cemetery and Zhang Yiwu Memorial Hall in series to serve the development of cultural tourism in Xinglongshan Scenic Area. When it is officially opened to traffic, the brand-new Avenue will bear the multiple expectations of people's livelihood travel, red research and tourism development, and hand over a heavy post-disaster reconstruction of people's livelihood for the mountainous areas in central and southern Yuzhong.