At 4:00 a.m. on May 1, 2022, with the last roar of the excavator, it marked the completion of the earth excavation of the foundation pit of Beima Road station, bid tj2-8 of Harbin rail transit line 3 phase II project of CCCC Second Highway Engineering Co., Ltd., which laid a solid foundation for the capping of the main structure of the station, the construction of shield interval and the construction of track laying foundation in the later stage.

Beima subway station of Harbin Metro Line 3 is an island type transfer station on the second floor of the underground and part of the third floor, which transfers with the future line 4. At the same time, the structure of highway river crossing channel is reserved on the negative first floor of the transfer section. The station undertakes civil construction, indirect collection and departure of shield area and the construction of track laying base of Northwest ring road. It is a key node station for the opening of Northwest ring road of line 3. The construction is difficult and the construction period is tight. In order to speed up the construction progress, the project builders only rest for less than two weeks during the Chinese New Year. They are not afraid of the severe cold, stick to the front line, plan and reserve materials in advance, and intensively deploy the winter construction scheme and protection scheme, At the same time, a number of thermal insulation measures for winter construction have been taken, such as building a double shed, covering a flame-retardant and thermal insulation quilt, heating and heating with a warm air gun, so as to promote the construction progress to the greatest extent under the condition of ensuring safety and quality standards.

Beima Road station is located underground at the intersection of Beima road and Kaiyuan street. It is surrounded by Baoyu high-rise residential buildings, which are 6.97 meters away from the commercial and residential buildings. There are more than 20 important pipelines around. The station is only 628 meters away from Songhua River. The geology belongs to water rich sand layer, and the groundwater is extremely rich. Groundwater occurs when the foundation pit is excavated for 3 meters, which is easy to cause water gushing, sand gushing and ground collapse; At the same time, station excavation is accompanied by 24 risks, including 1 level-1 risk, 10 level-2 risk and 13 level-3 risk, which puts forward higher requirements for risk prevention and control of foundation pit excavation. Harbin Metro Group and the project department have studied the construction scheme for many times and hired experts to conduct risk assessment. According to the characteristics of difficult excavation and high construction risk, more than 60 dewatering wells are set inside the foundation pit for foundation pit dewatering. In order to ensure the stability of the foundation pit, 530 steel supports with a length of 34 meters and a diameter of 0.69 to 0.8 meters are erected horizontally inside the foundation pit; In order to prevent water leakage from the joint of the diaphragm wall, the construction unit adopts the advanced technology of ECR water leakage detection, rotary jet grouting reinforcement of the joint of the diaphragm wall, backward grouting reinforcement and other measures to ensure the safety of foundation pit excavation without leakage. By taking the above series of safety assurance measures, the construction risks were effectively avoided and various difficulties were overcome.

Beima Road station is the station with the widest foundation pit in the northwest ring of Metro Line 3. In order to prevent the risks in the excavation process, the builders scientifically organized the excavation of the foundation pit based on the principle of “slotted support, support before excavation, layered excavation and no over excavation”, so as to ensure the safety and reliability of the support system. When excavating adjacent foundation pits, follow the construction sequence of deep first and shallow at the same time. Overcome difficulties in the process, break the temporary ground wall while excavating. The temporary ground wall runs transversely through the foundation pit, with a breaking height of 18 meters and is broken in seven layers.

Beima Road station has a total length of 316 meters, a maximum width of 34.7 meters and a maximum depth of 27.33 meters. The foundation pit of the station is the northwest ring, with the largest width. It is internally equipped with external foundation pit at the entrance and exit, reserved foundation pit of line 4 channel on the negative third floor of the transfer section, and reserved foundation pit of highway River Crossing Tunnel on the negative first floor. The construction structure is extremely complex and the excavation is difficult. The earthwork volume is about 150000 cubic meters. The construction unit is equipped with 8 excavators, of which two crawler telescopic boom excavators excavate synchronously in the East and West sections respectively, and the maximum daily earth transportation is more than 150 vehicles, up to more than 3000 cubic meters. The north side of the station site is restricted by the high-voltage line, and the earth excavation can only be carried out on one side. In order to ensure the stability of the foundation pit to the greatest extent, the steel support shall be erected in time, and the main tasks shall be followed up in time. The project department shall be equipped with a number of large cranes and gantry cranes to cooperate with the transportation and installation of materials. The East and west areas shall be promoted on many sides at the same time and spread in an all-round way, forming a flow operation, which has laid a solid foundation for the opening of the northwest Ring Road.