The Huixian-Tianshui Expressway in Gansu Section of the Shiyan-Tianshui Expressway is a transverse connection line of the Fuzhou-Yinchuan Expressway in the national expressway network, and also an important expressway export in the southeast of our province. The route has a total length of 189 kilometers, with 35 kilometers of connecting lines constructed simultaneously, and an estimated investment of 20.621 billion yuan. The project started construction in December 2011 and is expected to be completed and open to traffic by the end of next year. In order to build the Gansu Section of the Shiyan-Tianshui Expressway into a premium project, the project office has persistently strengthened management, taken multiple measures to enhance supervision, strictly enforced discipline and increased rewards and penalties, thereby promoting the continuous and steady improvement of construction project quality.

　　Iron determination to build a premium project

　　The Shiyan-Tianshui Expressway is located in the mountainous area of Longnan in our province. Most of the route is laid along gullies and river channels, and passes through many adverse geological sections such as landslides, collapses, and accumulations, as well as multiple geological fault zones. The geological conditions are complex and construction is difficult. To ensure project quality, the project office took clear responsibility as a breakthrough and carried out quality improvement activities in depth.

　　The project implemented the owner's representative responsibility system, dividing the 26 civil engineering project departments and 8 supervision departments along the entire line into 9 owner's representative responsibility zones, and further dividing the subsequently started pavement, building construction, and greening projects into 9 owner's representative responsibility zones. Each owner's representative manages the site, promptly grasps site dynamics, solves problems on site, and strengthens contact, supervision, and management of construction and supervision units. At the same time, the project office insists on holding daily evening video conferences among Chengxian, Huixian, Xihe, and the owner's representative workstation four locations to listen to work reports from owner's representatives, promptly study and solve problems arising at the construction site, and arrange and deploy follow-up work, achieving daily clearance and settlement.

　　To achieve full-process controllability of project quality, the project office focused on strengthening quality supervision and inspection. According to the construction stage, control points were analyzed in advance. The project office organized resident senior supervisors and technical directors to hold process seminars, formulated special construction quality control measures, and uniformly disseminated them throughout the project. Up to now, the project office has issued special guidance documents for beam slab prefabrication, rebar tying, abutment backfill, tunnel concealed works, pavement base construction, etc., and used them as the main basis for on-site quality control. In addition to enhanced daily inspections by owner's representatives, the central laboratory increased the frequency of inspection and acceptance. The project office also carried out quality "look-back" activities in stages, conducting comprehensive inspections of completed subgrade, bridge, tunnel, and other projects every quarter, focusing on concrete strength, geometric dimensions, three-back backfill, subgrade compaction, and masonry engineering quality, and promptly rectifying discovered problems and hidden dangers.


　　Iron-handed full-process quality control

　　To ensure project quality, the project office fully implemented standardized management, improved and perfected the standardized management system, compiled and issued a complete set of standardized process guidelines, and focused on promoting standardization of station construction, construction processes, and management behaviors.

　　In terms of station construction standardization, the project office implemented the "three concentrations" system, namely centralized concrete mixing, centralized prefabrication of concrete components, and centralized processing of rebar, implementing factory-style production. To implement this system, the project office strictly reviewed the station layout planning, functional zoning, and production processes according to the actual conditions of each contract section, and carried out centralized rectification of sites that did not meet factory production conditions, bringing the construction site up to construction standards.

　　In terms of personnel, equipment, and material management, to ensure personnel and construction equipment are in place, the project office implemented the "three admissions" system, namely strict admission of incoming personnel, construction equipment, and construction raw materials. At the same time, according to schedule node requirements, the project office regularly verified the arrival rate and stability rate of incoming personnel and construction equipment, increased supervision of key equipment arrival, focused on ensuring the arrival of key equipment for tunnel construction, pile foundation construction, and rebar processing, and tracked and verified their usage. To strengthen source control of raw materials, the project office conducted public joint bidding for 14 major materials such as rebar and cement, and publicized the bidding results. The project office dynamically supervises suppliers, implements a strict material sample retention and comparison system, conducts strict testing of products from various manufacturers through the central laboratory, built a "material sample retention room," and established a credit ledger to ensure reliable quality of incoming materials and accountability.

　　In terms of construction processes, the project office installed "black boxes" to fully record mixing parameters, adopted CNC equipment for rebar processing, used roll welding machines for rebar cage fabrication in pile foundation and pier column construction, adopted CNC bending machines, positioning formwork, and high-strength mortar spacer block processes for beam slab skeleton rebar, and promoted processes such as combed bundling, intelligent tensioning, and vacuum-assisted grouting in beam slab prestressing construction. In tunnel engineering, new equipment such as multi-arm rock drilling jumbos and wet spraying machines were introduced. In subgrade filling, the characteristics of various subgrade fill materials were carefully analyzed, vibratory sheep-foot rollers were configured throughout the line, and construction measures such as grid method soil spreading, line-hanging layer thickness control, and setting out subgrade boundary lines every three layers were adopted. Filling processes and auxiliary testing methods were clarified, the central laboratory conducted inspections every three layers, and GPS positioning systems were installed on rollers to monitor rolling passes and compaction quality. The project office also implemented process improvement, construction method innovation, and reasonable suggestion reward measures, encouraging participating units and individuals to propose new processes and methods conducive to quality control. Once a process or method was adopted, corresponding rewards were given to both units and individuals.


　　Iron discipline to eliminate quality hidden dangers

　　The project office fully implemented the quality responsibility registration card system, with on-site technicians, on-site supervisors, and owner's representatives jointly signing responsibility cards. Statistics and ledgers and photo archives were established for "three backs," "six parts," access ramps, and fill subgrade slope areas, implementing full-process monitoring. For common quality defects, based on extensive summary of construction experience, the project office carefully summarized and compiled a special "Quality Defect Prevention and Control Manual," which elaborates in detail on the manifestations, harm levels, prevention and control measures, and control links of common quality defects in four parts: general, bridge, subgrade, and tunnel, providing important guidance for the prevention and treatment of common quality defects. In bridge construction, on-site monitoring of rebar processing, formwork installation, protective layer thickness control, and prestressing quality was strengthened, and on-site construction of various node stress parts such as wet joints and hinge joints was strictly controlled, ensuring the connection quality of various stress rebar and concrete pouring quality, and ensuring structural stability. In tunnel engineering, quality control was strengthened for excavation cross-section, initial support thickness, arch frame connection, arch frame spacing, anchor rod quantity and size angle, secondary lining thickness, and central drainage ditch, and the inverted arch construction process was standardized. In the on-site management of protection and drainage facilities, quality supervision was strengthened through regular on-site destructive inspections of engineering geometric dimensions, construction processes, and internal quality. In pavement base construction, process control was carried out from mixture gradation and cement dosage, transportation, paving, rolling, and curing, and timely treatment was given to water accumulation and segregation defects during pavement construction.