On the evening of July 31, with a rumbling roar, the left line of the Taohuazhai Station–Huaxi South Station section on Guiyang Rail Transit Line 3, constructed by China Railway Shanghai Engineering Bureau Group, successfully broke through. With this, the section has achieved dual-line breakthrough.

The left line of the Taohuazhai Station–Huaxi South Station section that broke through this time was launched from the small-mileage end of Huaxi South Station and excavated southward along Qingxi Road, successively passing beneath the Mengxi Road underpass and the Yangliutang Tunnel of the Southwest Ring Railway, before reaching the receiving shaft at the large-mileage end of Taohuazhai Station. The section is 952 meters long, with a minimum horizontal curve radius of 650 meters and a maximum longitudinal slope of 33.6‰. The longitudinal profile of the line forms a "V"-shaped slope, and a connecting passage with a pump room is provided in the section. The construction section has complex geological conditions, mostly consisting of dolomite and argillaceous dolomite strata with uneven hardness and softness, and is characterized by many karst caves, abundant groundwater, high pressure, and numerous risk sources along the underpass route, resulting in high construction risk.

During construction, the project department, on the one hand, closely monitored the progress and condition of the shield machine, repeatedly invited experts to demonstrate and provide guidance on multiple construction plans including the underpass beneath the railway, strengthened coordination and communication with all parties externally, formulated reasonable and feasible shield driving plans internally, and completed the preparation of various plans, providing strong technical guarantees and support for shield launching and driving. On the other hand, after fully considering the stratum characteristics, they identified construction risks in advance, continuously optimized construction technical plans in light of actual construction conditions, adjusted shield driving parameters, reasonably selected the mix proportion for simultaneous grouting, and strengthened ring-sealing grouting inside the tunnel to ensure safe driving distances for the left and right lines and solve the problem of water and soil gushing. They also used advanced geological forecasting for prediction and pre-reinforcement, and used detection data and shield driving parameters to guide secondary grouting in real time, taking sufficient safeguard measures to effectively solve the problem of segment uplift; they adopted methods such as strengthened monitoring of ground and in-tunnel data to ensure smooth shield construction.

Next, the ancillary structures of this contract section will be carried out simultaneously with the main shield works of the Tongmu–Taohuazhai section, striving to complete the construction task as soon as possible.